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Gleicher Lohn f¸r gleiche Arbeit? Zum Zusammenhang zwischen Gewerkschaftsmitgliedschaft und Lohnstruktur in Westdeutschland 1985?1997
Diese Arbeit untersucht den Zusammenhang zwischen dem gewerkschaftlichen Nettoorganisationsgrad als Maþ f¸r die Gewerkschaftsmacht und der Lohnstruktur in und zwischen Segmenten des deutschen Arbeitsmarktes in den Jahren 1985 bis 1997 auf Basis der IAB-Besch‰ftigtenstichprobe. Dem Datensatz werden prognostizierte individuelle Wahrscheinlichkeiten der Mitgliedschaft in einer Gewerkschaft aus Sch‰tzungen von Beck und Fitzenberger (2004) hinzugespielt. Einem Versicherungsmotiv f¸r die Gewerkschaftsmitgliedschaft entsprechend geht
Bernd Fitzenberger; Karsten Kohn
Zellphysiologische Studien an Bryophyllum im Zusammenhang mit dem t‰glichen S‰urewechsel
Zusammenfassung Der Preþsaft aus den Bl‰ttern vonBryophyllum tubiflorum undBr. Daigremontianum zeigt im Herbst und im Winter bei einer Zusatzbeleuchtung am Tage mit 200-W-Parabollampen bei einer durchschnittlichen Licht-intensit‰t von 15.000 Lux morgens einen pH-Wert um 4,4 und nachmittags um 5,6: im Sommer liegt der pH-Wert an sonnigen Tagen morgens um 4,2 und nachmittags um 5,6. An tr¸ben Tagen tritt auch bei
Gudrun Overbeck; I. Einleitung
Kartierung von wasserges‰ttigten Firnschichten auf dem Kesselwandferner mit dem EMR-Verfahren
Zusammenfassung: Die r‰umliche Verteilung von Wasser im Akkumulationsgebiet eines Gletschers ist im Zusammenhang mit der hydrolo≠ gischen Bilanz des Einzugsgebietes von besonderem Interesse. Es ist bekannt, daþ sich im Akkumulationsgebiet von Alpengletschern an der Grenzfl‰che zwischen wasserdurchl‰ssigern Firn und wasserundurchl‰ssigem Gletschereis eine Wassertafel ausbildet, deren Ortung bisher nur durch Bohrung mˆglich war. Daher war die Erprobung eines elektromagnetischen Impulsverfahrens (Elvl
Von F. Thyssen; H. Eisner; N. Blindow; W. Ambach
Erkl‰rungshypothese zum Zusammenhang von Kˆrpergewicht, Fettreserven und Ovulationsrate in nicht‰quatorialen Cerviden
Nicht‰quatoriale freilebende Cerviden besitzen eine saisonale Reproduktionsstrategie, die dem j‰hrlichen Pflanzenwachstum angepaþt ist. Es bestehen Verhaltensweisen und physiologische Adaptionen, die zur Fettdeponierung im Herbst und zum Fettabbau im Winter f¸hren. Diese Fettdeponierung bestimmt zum grˆþten Teil das Kˆrpergewicht der weiblichen St¸cke. Unter allen nicht‰quatorialen Cerviden besteht eine starke Korrelation zwischen Kˆrpergewicht, Ovulationsrate und Zeitpunkt des ÷strus, die aber bei Anwendung
W. T. Flueck
Besteht ein Zusammenhang zwischen der Wirbelzahl auf den Fingerbeeren und der Stellung in der Geschwisterfolge?
It was stated by Birdsong and Rashad (1972) that the child of birth order number six of Korean families has significantly more true whorls on the finger tips than older brothers and sisters. To verify this assertion we studied a sample of all members of 43 normal German families with 5 or more legitimate children. The findings of the epidermal
H. Brehme; W. W. Wittmann
Heterotype Mischbarkeit zwischen Wolframit- und Rutilgruppe
Zusammenfassung Untersucht wurden die heterotypen Mischsysteme zwischen Wolframit- und Rutilgruppe FeNbO4-TiO2, FeNbO4-FeTaO4, FeWO4- FeTaO4 und FeWO4-TiO2. Aus der Stereometrie der Gitter l‰þt sich absch‰tzen, daþ ein statistischer Ðbergang beider Gittertypen nicht wahrscheinlich ist.
Helmut Schrˆcke
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument onboard the National Aeronautics and Space Administration's Terra spacecraft has an along-track stereoscopic capability using its a near-infrared spectral band to acquire the stereo data. ASTER has two telescopes, one for nadir-viewing and another for backward-viewing, with a base-to-height ratio of 0.6. The spatial resolution is 15 m in the horizontal plane. Parameters such as the line-of-sight vectors and the pointing axis were adjusted during the initial operation period to generate Level-1 data products with a high-quality stereo system performance. The evaluation of the digital elevation model (DEM) data was carried out both by Japanese and U.S. science teams separately using different DEM generation software and reference databases. The vertical accuracy of the DEM data generated from the Level-1A data is 20 m with 95% confidence without ground control point (GCP) correction for individual scenes. Geolocation accuracy that is important for the DEM datasets is better than 50 m. This appears to be limited by the spacecraft position accuracy. In addition, a slight increase in accuracy is observed by using GCPs to generate the stereo data. ?? 2005 IEEE.
Fujisada, H.; Bailey, G. B.; Kelly, G. G.; Hara, S.; Abrams, M. J.
Quantitative Beziehungen zwischen den Eigenschaften von Futterquellen und dem Verhalten von Sammelbienen
1.Bei unbeschr‰nktem Nachfluþ von Zuckerwasser trinkt eine Sammelbiene bei jedem Besuch um so mehr, d.h. sie erreicht eine um so grˆþere ÑAbflugmagenf¸llungì, je konzentrierter die angebotene Zuckerlˆsung ist (Abb. 5 und 5a)2.Die Trink-Geschwindigkeit bei unbeschr‰nktem Nachfluþ ist bei niederen und mittleren Zuckerkonzentrationen gleich groþ (Abb 6); bei hohen Konzentrationen sinkt sie etwas ab, vermutlich wegen der grˆþeren Viskosit‰t konzentrierter Zuckerlˆsungen.3.Wird
JosuÈ A. N˙Òez
Beziehungen zwischen Kˆrperbau und Lebensweise bei Blenniidae (Pisces) aus dem Roten Meer. I. ƒuþere morphologie
The external morphology of 5 species of salariin Blenniidae has been examined. Differences have been established between Salarias fasciatus living in the sublittoral, Antennablennius hypenetes, Istiblennius edentulus and I. flaviumbrinus inhabiting the eulittoral zone, and, especially, Alticus kirkii living on steep rocks of the supralittoral zone. The rays of the anal and (partly) pectoral fins terminate in little hooks; these
C. D. Zander
Plage des bˆsen oder kleinod der schˆpfung: vom netz zur spinne zwischen dem meissner und trakl
For centuries spiders and cobwebs have formed programmatic iconographic images which often change their meaning in the course of literary epochs and thus help to uncover the aspects of epoch changes. Even though the spider belongs to the rarer animal symbols in German litrature, the rare incidence of this image between the Middle Ages and modernism gains in significance when
Holger Eckhardt
Ðber Zusammenh‰nge zwischen dem CO 2 Austausch und der Abgabe von Wasserdampf durch Bryophyllum daigremontianum Berg
1.The transpiration in leaves of Bryophyllum daigremontianum exactly follows the changes in consumption of atmospheric carbon dioxide (caused by the Crassulaceen acid metabolism) during the light and dark periods. After removal of the epidermis no distinct rhythm in the course of transpiration can be observed any more, whereas the characteristic CO2 exchange continues in an unchanged matter. For this reason
Manfred Kluge; Karl Fischer
Beziehungen zwischen Kˆrperbau und Lebensweise bei Blenniidae (Pisces) aus dem Roten Meer. III. Morphologie des Auges
The morphology of the eyes of 3 salariin Blenniidae have been investigated and compared: Salarias fasciatus (inhabiting the sublittoral), Istiblennius edentulus (eulittoral), and Alticus kirkii (supralittoral). An effective protection against desiccation in A. kirkii is offered by the very thick cornea conjunctiva. Extension of the visual field in this species is achieved by protrusion of the eyes from the head,
C. D. Zander
Digital Terrain Analysis Based on DEM
The digital elevation model (DEM), an important source of information, is usually used to express a topographic surface in\\u000a three dimensions and to imitate essential natural geography. DEM has been applied to physical geography, hydrology, ecology,\\u000a and biology. This study analyzed digital elevation data sources and their structure, the arithmetic of terrain attribute extraction\\u000a from DEM and its applications, and
Huaxing Bi; Xiaoyin Li; Mengxia Guo; Xin Liu; Jun Li
SRTM DEM and its application advances
The Shuttle Radar Topography Mission (SRTM) provides for the first time a near-global high-resolution digital elevation model (DEM) with great advantages of homogeneous quality and free availability. The last 10 years or so have seen rapid advances in the data processing and applications of SRTM DEM. From the perspective of SRTM, we present in this article a brief overview of
Liping Yang; Xingmin Meng; Xiaoqiang Zhang
TanDEM-X high resolution DEMs and their applications to flow modeling
NASA Astrophysics Data System (ADS)
Lava flow modeling can be a powerful tool in hazard assessments; however, the ability to produce accurate models is usually limited by a lack of high resolution, up-to-date Digital Elevation Models (DEMs). This is especially obvious in places such as Kilauea Volcano (Hawaii), where active lava flows frequently alter the terrain. In this study, we use a new technique to create high resolution DEMs on Kilauea using synthetic aperture radar (SAR) data from the TanDEM-X (TDX) satellite. We convert raw TDX SAR data into a geocoded DEM using GAMMA software [Werner et al., 2000]. This process can be completed in several hours and permits creation of updated DEMs as soon as new TDX data are available. To test the DEMs, we use the Harris and Rowland [2001] FLOWGO lava flow model combined with the Favalli et al. [2005] DOWNFLOW model to simulate the 3-15 August 2011 eruption on Kilauea's East Rift Zone. Results were compared with simulations using the older, lower resolution 2000 SRTM DEM of Hawaii. Effusion rates used in the model are derived from MODIS thermal infrared satellite imagery. FLOWGO simulations using the TDX DEM produced a single flow line that matched the August 2011 flow almost perfectly, but could not recreate the entire flow field due to the relatively high DEM noise level. The issues with short model flow lengths can be resolved by filtering noise from the DEM. Model simulations using the outdated SRTM DEM produced a flow field that followed a different trajectory to that observed. Numerous lava flows have been emplaced at Kilauea since the creation of the SRTM DEM, leading the model to project flow lines in areas that have since been covered by fresh lava flows. These results show that DEMs can quickly become outdated on active volcanoes, but our new technique offers the potential to produce accurate, updated DEMs for modeling lava flow hazards.
Wooten, Kelly M.
Zwischenartliche Beziehungen zwischen freilebenden Guanaco ( Lama guanicoe ) und angesiedeltem Rotwild ( Cervus elaphus ) in Argentinien
Das in Argentinien eingef¸hrte Rotwild besiedelt derzeit groþe Gebiete von Patagonien. Das Verbreitungsgebiet ¸berschneidet sich teilweise mit der Verbreitung der einheimischen Kamelart Guanaco. Die vorliegende Mitteilung beschreibt direkte Beziehungen zwischen den beiden Arten in einem ÷kotongebiet des Nahuel Huapi Nationalparks. Beide Arten wurden oft zusammen beim ƒsen an gleichen Orten und zur gleichen Zeit beobachtet, und die Distanz zwischen Individuen
W. T. Flueck
DEM simulation of oblique boudinage
NASA Astrophysics Data System (ADS)
Boudinage occurs in mechanically layered rocks if there is a component of lengthening parallel to a brittle layer in a ductile matrix. Asymmetric boudin structures develop if the extension is not layer-parallel, and the boudin blocks rotate. The amount of block rotation is commonly used as shear indicators; therefore, it has been well studied. However, full oblique boudinage has not been modeled yet. We simulated full boudinage processes during layer oblique extension using DEM simulation software. In our boudinage model, the initial setup consists of three layers: there is a brittle center oblique layer in a ductile matrix. We simulated horizontal extension by applying vertical displacement: the top and bottom boundaries of the model are moved at a constant velocity, while the side boundaries were force controlled by applying a constant confining force. By varying the cohesion of the competent layer, various type and shape of boudin blocks were developed. By varying the angle of the competent layer, the rotation of the boudin blocks changed. With higher dip of the competent layer, the rotation of the boudin blocks is more consistent. We also studied the stress field during the simulation. The results show, that in case of ductile material, the disruptions of the layer are driven by the angle of the layer and not the orientation of the external stress field.
Komoroczi, Andrea; Abe, Steffen; Urai, Janos L.
Shuttle Radar Topography Mission: A Global DEM.
National Technical Information Service (NTIS)
Digital topographic data are critical for a variety of civilian, commercial, and military applications. Scientists use Digital Elevation Models (DEM) to map drainage patterns and ecosystems, and to monitor land surface changes over time. The mountain-buil...
T. G. Farr M. Kobrick
Gespr‰chstranskription auf dem Computer - das System EXMARaLDA
Der Einsatz des Computers zur Transkription nat¸rlicher Gespr‰che ist in der Pra- xis zwar weit verbreitet, die schnelle Weiterentwicklung der Computertechnologie hat aber dazu gef¸hrt, dass verschiedene Systeme oft scheinbar zusammenhangs- los nebeneinander stehen, ohne dass ihre Gemeinsamkeiten und Unterschiede Ge- genstand einer umfassenden theoretischen Betrachtung w‰ren. Der vorliegende Aufsatz will einen Beitrag zu einer solchen theoretischen Betrachtung der Gespr‰chstranskription
Thomas Schmidt
Shaded relief of the state of Arizona developed from 1-degree US Geological Survey (USGS) Digital Elevation Models (DEMs). DEM is a terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. ...
Shaded relief of the state of Nevada developed from 1-degree US Geological Survey (USGS) Digital Elevation Models (DEMs). DEM is a terminology adopted by the USGS to describe terrain elevation data sets in a digital raster form. ...
Online-Kommunikation als Kultur
\\u000a Die Cultural Studies gehen von einem engen Zusammenhang zwischen Kultur und Kommunikation aus. Vor diesem Hintergrund haben\\u000a sie sich schon sehr fr¸h mit den Online-Medien auseinandergesetzt. Ziel des vorliegenden Ðberblicks ist es zun‰chst, einige\\u000a wichtige Grundz¸ge der Cultural Studies aufzuzeigen, die ihre Perspektive auf Online- Medien charakterisieren. Dann wird genauer\\u000a auf die ÇCybercultural Studiesí eingegangen, ein Titel, unter dem die
Maren Hartmann; Friedrich Krotz
Aktuelle Weiterentwicklungen auf dem Gebiet des UDK
1 Abstrakt Der Umweltdatenkatalog (UDK) ist ein de-facto Standard f¸r Metadaten im Umwelt- bereich. In diesem Artikel werden die neusten Entwicklungen des UDK beschrieben. Neben einer Reihe von Verbesserungen auf dem Gebiet der Recherche wurden seit der Version 4.2 alle internen und externen Schnittstellen sowohl des Windows- als auch des WWW-UDK auf XML umgestellt. Zu diesem Zweck wurde eine eigene
Fred Kruse
NASA Astrophysics Data System (ADS)
Global DEMs are fundamental for global applications and are necessary also at the local scale, in regions where local models are not available. Local DEMs are preferred when they are available and if are characterized by better accuracies and resolutions. In general, two problems arise. Firstly, an interest region could be patched by several partly overlapping DEMs that present similar accuracies and spatial resolutions: they should be merged in a unified model. Moreover, even when the interest region is covered by one unified DEM, local DEMs with better accuracy could be available and should be used to locally improve it. All these problems have been addressed within HELI-DEM project. HELI-DEM (HELvetia-Italy Digital Elevation Model) is a project that has been funded by the European Regional Development Fund (ERDF) within the Italy-Switzerland cooperation program. It started in 2010 and finished at the end of 2013. The involved institutions in the project were Fondazione Politecnico di Milano, Politecnico di Milano, Politecnico di Torino, Regione Lombardia, Regione Piemonte and Scuola Universitaria della Svizzera Italiana. One specific aim of the project was the creation and the publication of a unified Digital Elevation Model for the part of the Alps between Italy and Switzerland. The interest area is prevalently mountainous, with heights that range from about 200 m to 4600 m. Three low Resolution DTMs (20-25-50 m of resolution) are available that partly overlap and patch the whole project area: they are characterized by accuracies of some meters. Also High Resolution DTMs (1-5 m) are available: they have accuracies of some decimeters but cover limited areas of the project. The various models are available in different reference frames (the European ETRF89 and the Italian Roma40) and are gridded either in cartographic or geographic coordinates. Before merging them, a validation of the input data has been performed in three steps: cross validation of LR DTMs, validation of LR DTMs by HR DTMs and final check by geodetic techniques. The comparisons confirm the accuracy of HR data and the presence of few local anomalies in LR DTMs. Considering the goal of the project and the previous results, two different DTMs have been produced. Both of them cover the whole project area (boundaries: ? = 7.80∞ East and ? = 10.70∞ East, ? = 45.10∞ North e ? = 46.70∞ North). They are gridded in ETRF2000 geographical coordinates and their spatial resolution is 2 ◊ 10-4 degrees. The former has been obtained by interpolating and merging all the input LR DTMs on a new common grid. This DTM has been called HD-1. HD-1 presents the same local anomalies of the LR DTMs used as input for the interpolation: therefore, at least in areas where better data (HR DTMs) are available, its correction was needed. In order to avoid sharp discontinuities, corrections obtained by HR DTMs have been filtered by a numerical FFT approach before applying them. The result of this correction has been called HD-2. HD-1 and HD-2 have already been published by an open access geoservice.
Biagi, L.; Caldera, S.; Carcano, L.; Lucchese, A.; Negretti, M.; SansÚ, F.; Triglione, D.; Visconti, M. G.
DEM simulation of experimental dense granular packing
In this study we present numerical analysis performed on the experimental results of sphere packings of mono-sized hard sphere whose packing fraction spans across a wide range of 0.59<{Phi}<0.72. Using X-ray Computed Tomography (XCT), we have full access to the 3D structure of the granular packings. Numerical analysis performed on thr data provides the first experimental proofs of how densification affects local order parameters. Furthermore by combining Discrete Element Method (DEM) and the experimental results from XCT, we investigate how the intergranular forces change with the onset of crystallization.
Hanifpour, Maryam; Allaei, Mehdi Vaez [Department of Physics, University of Tehran, Tehran (Iran, Islamic Republic of); Francois, Nicolas; Saadatfar, Mohammad [Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra (Australia)
Precise Global DEM Generation by ALOS PRISM
NASA Astrophysics Data System (ADS)
The Japan Aerospace Exploration Agency (JAXA) generated the global digital elevation/surface model (DEM/DSM) and orthorectified image (ORI) using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi"), which was operated from 2006 to 2011. PRISM consisted of three panchromatic radiometers that acquired along-track stereo images. It had a spatial resolution of 2.5 m in the nadir-looking radiometer and achieved global coverage, making it a suitable potential candidate for precise global DSM and ORI generation. In the past 10 years or so, JAXA has conducted the calibration of the system corrected standard products of PRISM in order to improve absolute accuracies as well as to validate the high-level products such as DSM and ORI. In this paper, we introduce an overview of the global DEM/DSM dataset generation project, including a summary of ALOS and PRISM, in addition to the global data archive status. It is also necessary to consider data processing strategies, since the processing capabilities of the level 1 standard product and the high-level products must be developed in terms of both hardware and software to achieve the project aims. The automatic DSM/ORI processing software and its test processing results are also described.
Tadono, T.; Ishida, H.; Oda, F.; Naito, S.; Minakawa, K.; Iwamoto, H.
DEM time series of an agricultural watershed
NASA Astrophysics Data System (ADS)
In agricultural landscape soil surface evolves notably due to erosion and deposition phenomenon. Even if most of the field data come from plot scale studies, the watershed scale seems to be more appropriate to understand them. Currently, small unmanned aircraft systems and images treatments are improving. In this way, 3D models are built from multiple covering shots. When techniques for large areas would be to expensive for a watershed level study or techniques for small areas would be too time consumer, the unmanned aerial system seems to be a promising solution to quantify the erosion and deposition patterns. The increasing technical improvements in this growth field allow us to obtain a really good quality of data and a very high spatial resolution with a high Z accuracy. In the center of Belgium, we equipped an agricultural watershed of 124 ha. For three years (2011-2013), we have been monitoring weather (including rainfall erosivity using a spectropluviograph), discharge at three different locations, sediment in runoff water, and watershed microtopography through unmanned airborne imagery (Gatewing X100). We also collected all available historical data to try to capture the "long-term" changes in watershed morphology during the last decades: old topography maps, soil historical descriptions, etc. An erosion model (LANDSOIL) is also used to assess the evolution of the relief. Short-term evolution of the surface are now observed through flights done at 200m height. The pictures are taken with a side overlap equal to 80%. To precisely georeference the DEM produced, ground control points are placed on the study site and surveyed using a Leica GPS1200 (accuracy of 1cm for x and y coordinates and 1.5cm for the z coordinate). Flights are done each year in December to have an as bare as possible ground surface. Specific treatments are developed to counteract vegetation effect because it is know as key sources of error in the DEM produced by small unmanned aircraft systems. The poster will present the older and more recent changes of relief in this intensely exploited watershed and notably show how unmanned airborne imagery might be of help in DEM dynamic modelling to support soil conservation research.
Pineux, Nathalie; Lisein, Jonathan; Swerts, Gilles; DegrÈ, Aurore
Erfassung der gesundheitsbezogenen Lebensqualit‰t mit dem deutschen SF8
Im Rahmen eines Vergleiches telefonischer und postalischer Befragungsmethoden wurde der SF-8 als Instrument zur Messung der gesundheitsbezogenen Lebensqualit‰t bei Erwachsenen eingesetzt. Die aus 1690ÝPersonen im Alter zwischen 25 und 66ÝJahren bestehende Stichprobe wurde randomisiert zur H‰lfte telefonisch und zur anderen H‰lfte postalisch befragt. Verglichen wurden die je nach Darbietungsmodus erzielten Ausf¸llraten, zentralen Tendenzen, Streuungen, Decken- und Bodeneffekte in den Messwerten
M. Erhart; R. Wetzel; A. Kr¸gel; U. Ravens-Sieberer
Multibaseline InSAR DEM reconstruction: the wavelet approach
Multibaseline synthetic aperture radar (SAR) interferometry can be exploited successfully for high-quality digital elevation model (DEM) reconstruction, provided that both noise and atmospheric effects are taken into account. A weighted combination of many uncorrelated topographic profiles strongly reduces the impact of phase artifacts on the final DEM. The key issue is weights selection. In the present article a wavelet domain
Alessandro Ferretti; Claudio Prati; Fabio Rocca
Greenland 5 km DEM, Ice Thickness, and Bedrock Elevation Grids
NSDL National Science Digital Library
The National Snow and Ice Data Center (NSIDC) has recently released a digital elevation model (DEM), ice thickness data taken by airborne ice penetrating radar, and bedrock thickness data (ice thickness subtracted from DEM) for 5 km of Greenland. The data are in ASCII format, and documentation (data collection, application, terminology, etc.) is available at the site.
Digital Elevation Model (DEM) files, 30-m resolution, for Virginia from US Geological Survey Web site: http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/7_min_dem/states/VA.html Files listed for VA but centered in TN, WV, and NC are not included. All file archives were downloaded an...
Method of DEM Data's Processing in Flood Simulation System
Flood simulation and forecasting is a hot topic of flood disaster research. DEM as the basic data plays a crucial role in the field. High resolution grid DEM data is able to supply exact terrain model to this work, but it brings on a bothering problem that the data is too big to reduce running efficiency in computer. Facing the
Sun Hai; Wang Cheng; Ren Bo
Hydrologic Information Extraction Based on Arc Hydro Tool and DEM
Extracting watershed features from DEM (Digital Elevation Model) is a very important task in Hydrologic study, and also it is the pre-process of hydrological simulation analysis. This paper introduces a very useful method for Hydrological simulation analysis based on extracting watershed features from DEM using Arc Hydro Tools. Arc Hydro is a geospatial data model especially GIS for Water Resources,
Jing Zhang; Qian Li; Huili Gong; Xiaojuan Li; Linrui Song; Jianwen Huang
Die Beurteilung des Schlaf-Wachzustands aus dem EEG und dem photisch evozierten Rindenpotential des Kaninchens
1.Beim Kaninchen ist im Gegensatz zu Katze und Ratte der deep sleep (sommeil rapide) nicht nachweisbar. Das Schlaf-EEG des Kaninchens ist gegen¸ber dem Wach-EEG nicht durch Frequenzsenkung, sondern durch Erhˆhung der Frequenzaktivit‰t im ganzen EEG-Frequenzbereich charakterisiert. Der spontane Wechsel des Schlaf-Wachzustands wird durch die ƒnderung der EEG-Frequenzaktivit‰t etwa ebenso gut wiedergegeben wie durch die ƒnderung der Spindelaktivit‰t.2.Die photisch evozierte Rindenantwort
Otto Vatter
Aspects of dem Generation from Uas Imagery
NASA Astrophysics Data System (ADS)
Since a few years, micro UAS (unmanned aerial systems) with vertical take off and landing capabilities like quadro- or octocopter are used as sensor platform for Aerophotogrammetry. Since the restricted payload of micro UAS with a total weight up of 5 kg (payload only up to 1.5 kg), these systems are often equipped with small format cameras. These cameras can be classified as amateur cameras and it is often the case, that these systems do not meet the requirements of a geometric stable camera for photogrammetric measurement purposes. However, once equipped with a suitable camera system, an UAS is an interesting alternative to expensive manned flights for small areas. The operating flight height of the above described UAS is about 50 up to 150 meters above ground level. This low flight height lead on the one hand to a very high spatial resolution of the aerial imagery. Depending on the cameras focal length and the sensor's pixel size, the ground sampling distance (GSD) is usually about 1 up to 5 cm. This high resolution is useful especially for the automatic generation of homologous tie-points, which are a precondition for the image alignment (bundle block adjustment). On the other hand, the image scale depends on the object's height and the UAV operating height. Objects like mine heaps or construction sites show high variations of the object's height. As a result, operating the UAS with a constant flying height will lead to high variations in the image scale. For some processing approaches this will lead to problems e.g. the automatic tie-point generation in stereo image pairs. As precondition to all DEM generating approaches, first of all a geometric stable camera, sharp images are essentially. Well known calibration parameters are necessary for the bundle adjustment, to control the exterior orientations. It can be shown, that a simultaneous on site camera calibration may lead to misaligned aerial images. Also, the success rate of an automatic tie-point generation differs extremely between several photogrammetric software packages. In this article, the calibration results of a suitable camera system will be shown. For a small format consumer grade camera, the authors will give the proof of ability for photogrammetric measurements purposes. This includes the results of different processing approaches for DEM generation of environments showing high object height variations.
Greiwe, A.; Gehrke, R.; Spreckels, V.; Schlienkamp, A.
Validation of SRTM X Band DEM over Himalayan Mountain
NASA Astrophysics Data System (ADS)
The present research study assesses the accuracy of the SRTM X band DEM with respect to high accuracy photogrammetric Digital Elevation Model (DEM) for parts of the Himalaya. The high resolution DEM was generated for Manali and nearby areas using digital aerial photogrammetric survey data of 40 cm Ground Sampling Distance (GSD) captured through airborne ADS80 pushbroom camera for the first time in Indian Himalayan context. This high resolution DEM was evaluated with Differential Global Positioning System (DGPS) points for accuracy assessment. The ADS80-DEM gave root mean square error (RMSE) of ~<1m and linear error of 1.60 m at 90 % confidence (LE 90) when compared with the DGPS points. The overall RMSE in vertical accuracy was 73.36 m while LE 90 was 75.20 m with regard to ADS80 DEM. It is observed that the accuracy achieved for part of Himalayan region is far less as compared to the values officially claimed. Thus, SRTM X band DEM should be used with due care in mountainous regions of Himalaya.
Gupta, R. D.; Singh, M. K.; Snehmani, S.; Ganju, A.
Evaluation of Aster Gdem v.2 Using GPS Checkpoints, Osgb dem Values and Photogammetrically Derived Dems
NASA Astrophysics Data System (ADS)
A 2010 study examining ASTER GDEM v1 data revealed accuracies of 12-25m and strong negative discrepancy biases compared to precise GPS observations, in several test sites in China. Rather than further investigating these, with the advent of ASTER GDEM v2 a new series of tests, also using precise GPS observations but also other DEMs, was performed. In these tests better than the expected 17m accuracies were found (RMSE values of 3.9m to 15.3m) and no strong biases.
Sadeq, H.; Drummond, J.; Li, Z.
DEM integrity monitor experiment (DIME) flight test results
This paper discusses flight test results of a Digital Elevation Model (DEM) integrity monitor. The DEM Integrity Monitor Experiment (DIME) was part of the NASA Synthetic Vision System (SVS) flight trials at Eagle-Vail, Colorado (EGE) in August\\/September, 2001. SVS provides pilots with either a Heads-down Display (HDD) or a Heads-up Display (HUD) containing aircraft state, guidance and navigation information, and
Maarten Uijt de Haag; Steve D. Young; Jonathon Sayre; Jacob Campbell; Ananth Vadlamani
DEM Reconstruction: A Markov-Chain Monte-Carlo Approach
NASA Astrophysics Data System (ADS)
We describe a Markov-Chain Monte-Carlo process using a Metropolis algorithm to derive Differential Emission Measures (DEMs) and element abundances from EUV line fluxes. This technique allows us to relax the smoothness constraint generally imposed on DEMs and also to determine confidence bounds on the computed values. We apply this method to solar spectral line data from SERTS (Solar EUV Rocket Telescope and Spectrograph).
Kashyap, Vinay; Drake, Jeremy
Using a DEM to Determine Geospatial Object Trajectories
This paper addresses the estimation of moving object trajectories within a geospatial coordinate system, using a network of video sensors. A high-resolution (0.5m grid spacing) digital elevation map (DEM) has been constructed using a helicopter-based laser range-finder. Object locations are estimated by intersecting viewing rays from a calibrated sensor platform with the DEM. Contin- uous object trajectories can then be
Robert T. Collins; Yanghai Tsin; J. Ryan Miller; Alan J. Lipton
Impact of DEM source and resolution on topographic seismic amplification
NASA Astrophysics Data System (ADS)
The impact of topographic attributes on the uneven distribution of seismic response and associated devastation has frequently been observed and documented during seismic events, but has rarely been investigated at a regional scale. Existing numerical and experimental techniques applied to explore the impact of topographic attributes in the aggravation of seismic response, have been limited to isolated and/or synthetic hills and ridges. Predicting the realistic regional impact of topographic seismic response is strongly dependent on the resolution and accuracy of regional topographic information. This study evaluates the topographic attributes and seismic parameters computed from multi-resolution and source DEMs, to investigate the impact of data source and resolution on the derived topographic seismic response. Methodologies are developed to readily derive the spatial distribution of relevant topographic attributes and seismic parameters, utilizing the multi-resolution and source DEMs. The impact of DEM source and resolution on slope gradient, relative height of terrain and shear wave velocity ( VS30) are addressed. It is observed that, even though, relatively coarse resolution DEMs underestimate the critical sites of steep slope gradient and the lower VS30 zones, this has limited impact on the derived normalized topographic aggravation factor. The free and easily accessible DEMs provide an opportunity for reasonable prediction of topographic seismic response, especially in near-real time. The slope gradient is observed to be the most sensitive topographic attribute to amplified seismic response, followed by the relative height.
Shafique, Muhammad; van der Meijde, Mark; Kerle, Norman; van der Meer, Freek
Discrete Element Modeling (DEM) of Triboelectrically Charged Particles: Revised Experiments
NASA Technical Reports Server (NTRS)
In a previous work, the addition of basic screened Coulombic electrostatic forces to an existing commercial discrete element modeling (DEM) software was reported. Triboelectric experiments were performed to charge glass spheres rolling on inclined planes of various materials. Charge generation constants and the Q/m ratios for the test materials were calculated from the experimental data and compared to the simulation output of the DEM software. In this paper, we will discuss new values of the charge generation constants calculated from improved experimental procedures and data. Also, planned work to include dielectrophoretic, Van der Waals forces, and advanced mechanical forces into the software will be discussed.
Hogue, Michael D.; Calle, Carlos I.; Curry, D. R.; Weitzman, P. S.
Precise baseline determination for the TanDEM-X mission
NASA Astrophysics Data System (ADS)
The TanDEM-X mission will strive for generating a global precise Digital Elevation Model (DEM) by way of bi-static SAR in a close formation of the TerraSAR-X satellite, already launched on June 15, 2007, and the TanDEM-X satellite to be launched in May 2010. Both satellites carry the Tracking, Occultation and Ranging (TOR) payload supplied by the GFZ German Research Centre for Geosciences. The TOR consists of a high-precision dual-frequency GPS receiver, called Integrated GPS Occultation Receiver (IGOR), and a Laser retro-reflector (LRR) for precise orbit determination (POD) and atmospheric sounding. The IGOR is of vital importance for the TanDEM-X mission objectives as the millimeter level determination of the baseline or distance between the two spacecrafts is needed to derive meter level accurate DEMs. Within the TanDEM-X ground segment GFZ is responsible for the operational provision of precise baselines. For this GFZ uses two software chains, first its Earth Parameter and Orbit System (EPOS) software and second the BERNESE software, for backup purposes and quality control. In a concerted effort also the German Aerospace Center (DLR) generates precise baselines independently with a dedicated Kalman filter approach realized in its FRNS software. By the example of GRACE the generation of baselines with millimeter accuracy from on-board GPS data can be validated directly by way of comparing them to the intersatellite K-band range measurements. The K-band ranges are accurate down to the micrometer-level and therefore may be considered as truth. Both TanDEM-X baseline providers are able to generate GRACE baselines with sub-millimeter accuracy. By merging the independent baselines by GFZ and DLR, the accuracy can even be increased. The K-band validation however covers solely the along-track component as the K-band data measure just the distance between the two GRACE satellites. In addition they inhibit an un-known bias which must be modelled in the comparison, so the differences between the computed baselines and the K-band ranges vary around a mean. In the end a systematic deviation or bias cannot be detected this way. A 3-D assessment of the baseline accuracies including biases can be gained by comparison of independently derived baselines as here from GFZ and DLR. Indeed it turns out that the different baselines show systematic differences of a few millimeters. From this it can be concluded that for the TanDEM-X mission an unknown bias in the baselines is possible which in turn would hurt the anticipated DEM accuracy limit. In order to control a possible baseline bias, a calibration chain via SAR calibration data takes has been invented in the TanDEM-X ground segment. This chain delivers corrections to the baseline bias so that unbiased baselines with sub-millimeter accuracies can be provided to secure the DEM accuracy requirement.
Koenig, Rolf; Moon, Yongjin; Neumayer, Hans; Wermuth, Martin; Montenbruck, Oliver; J‰ggi, Adrian
Removing non-ground points from automated photo-based DEM and evaluation of its accuracy with LiDAR DEM
NASA Astrophysics Data System (ADS)
Three sets of DEM, including LiDAR, stereo photo based DEM, and contour-based DEM, were created using different tools and sources. Because different tools produce different raster data sets, they were reprojected into the same coordinate system and converted to point clouds as vector format, then a triangulated irregular network (TIN) retaining all grid or mass points was created from each point coverage. Corresponding orthophoto involved in extracting stereo photo DEM, classified by object-oriented approach to create vector polygons representing non-ground points (building and vegetation classes) and bare-ground elevation points. Non-ground points were removed from stereo pairs DEM using classified orthophoto polygons, and filled with contour DEM data. Also a 5th order trend surface over photo-based DEM was fitted and non-ground points were removed and filled using local interpolation. It was observed that automated photo-based extraction yields high precision terrain models in a short time, reducing manual editing; their accuracy is strictly related to image quality and terrain features. Results showed that such photogrammetric extracted DEM represents better accuracy along x and y directions than LiDAR does, while LiDAR has the best vertical accuracy, compared to other DEMs. The differences between horizontal errors are large since there were no significant differences between vertical errors of LiDAR and photo-based DEM. This indicates that there is a good correlation between elevation points of DEMs, and a stereo pair-based DEM can be a good substitute, whenever LiDAR is not affordable. This study provides several important insights into the magnitudes and spatial patterns of LiDAR and photo-based DEM errors, further studies need to verify the error extent in more diverse landscape. However, automated photo-based DEM extraction is currently an efficient method for collecting data useful for rural and small study area.
Dehvari, Abdolhamid; Heck, Richard John
Reducing the DEM Error Effect in Differential Interferometry
RESUME Differential interferometric synthetic aperture radar (DInSAR) products are subject to a number of errors, some intrinsic in the phase measurements and others from third-party data such as orbits and digital elevation models (DEMs). The effect of these on product quality depends on the magnitude of the errors and the type of method employed to generate the differential phase. This
Andrew Sowter; Mark Warren
Mass transfer rates in a DEM electrochemical cell
The mass transfer characteristics of a DEM electrochemical cell were studied in both the presence and absence of a Netlon plastic mesh turbulence promotor. Two different modes of operation were used, one with a divided and the other with an undivided cell. Mass transfer coefficients were determined using the limiting current technique, with the cathodic reduction of potassium ferricyanide ion
W. M Taama; R. E. Plimley; K. Scott
Estimating impact force of granular avalanche on obstacles by DEM
NASA Astrophysics Data System (ADS)
The paper presents a DEM model which allows the simulation of dry granular avalanche flow down incline. It allows the simulation of the flow pattern and computation of impact forces on rigid obstacles. The model is compared with experimental data in literature. The experiments include granular flow along an inclined channel and three-dimensional free surface flow along an inclined cute merging into a horizontal run-out region. The introduction of the constraint of particle rotation allows realistic description of the flow behavior. The influence of the model parameters on granular flow is studied, e.g. the run-out distance, deposition pattern, flow pattern and impact forces against obstacle. The three-dimensional DEM is an appropriate tool for modeling granular flows and their interactions with obstacles. Due to the fully three-dimensional approach it is possible to calculate the impact forces with these simulation techniques. It is shown that the model performance is strongly dependent on the rotation control. Without any rotation constraint the flow behavior of rough and angular granules cannot be described by DEM correctly. The comparison of impact forces and flow patterns with laboratory experiments shows the potential of DEM for a wide range of laboratory setups.
Teufelsbauer, Harald; Wang, Yongqi; Wawra, Markus; Wu, Wei
Messung der gesundheitsbezogenen Lebensqualit‰t mit dem SF8
Mit dem SF-8 wurde im telefonischen Gesundheitssurvey 2003 ein relativ neues Instrument zur Messung der gesundheitsbezogenen Lebensqualit‰t eingesetzt, das Ergebnisse liefert, die mit denen des international meistbenutzten SF-36 vergleichbar sind. Durch den telefonischen Gesundheitssurvey 2003 werden bundesweit repr‰sentative Daten f¸r die 18-j‰hrige und ‰ltere Wohnbevˆlkerung in Deutschland bereitgestellt. Da neben der gesundheitsbezogenen Lebensqualit‰t auch umfassende Informationen zu chronischen Krankheiten und
U. Ellert; T. Lampert; U. Ravens-Sieberer
DEMñCFD modeling of a fluidized bed spray granulator
Coupled DEMñCFD simulations have been performed to study the fluid and particle dynamics in a fluidized bed spray granulator on the scale of individual particles. The aim of this study is to develop a model of a fluidized bed granulator by combining the gas and particle dynamics with a simple model of particle wetting. Based on material tests, the collision
L. Fries; S. Antonyuk; S. Heinrich; S. Palzer
DEMS - a second generation diabetes electronic management system.
Diabetes electronic management system (DEMS) is a component-based client/server application, written in Visual C++ and Visual Basic, with the database server running Sybase System 11. DEMS is built entirely with a combination of dynamic link libraries (DLLs) and ActiveX components - the only exception is the DEMS.exe. DEMS is a chronic disease management system for patients with diabetes. It is used at the point of care by all members of the diabetes team including physicians, nurses, dieticians, clinical assistants and educators. The system is designed for maximum clinical efficiency and facilitates appropriately supervised delegation of care. Dispersed clinical sites may be supervised from a central location. The system is designed for ease of navigation; immediate provision of many types of automatically generated reports; quality audits; aids to compliance with good care guidelines; and alerts, advisories, prompts, and warnings that guide the care provider. The system now contains data on over 34000 patients and is in daily use at multiple sites. PMID:10764939
Gorman, C A; Zimmerman, B R; Smith, S A; Dinneen, S F; Knudsen, J B; Holm, D; Jorgensen, B; Bjornsen, S; Planet, K; Hanson, P; Rizza, R A
Digital Elevation Model files, 30-m resolution, for North Carolina from US Geological Survey Web site: http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/7_min_dem/states/NC.html Files listed for NC but centered in TN, GA, and VA are not included. All file archives were downloaded an...
The research on automatically created contour's algorithm based on DEM
Contour line is a closed curve that joined by points of the same elevation. This paper puts forward a new algorithm of creating contour line based on DEM, which uses the method of tracking the same elevation point to study the algorithm based on regular grid. This paper will be divided the algorithm of creating contour line into four sub-algorithms,
Aijun Xu; Qingquan Li
Entwicklungsperspektiven von Social Software und dem Web 2.0
NASA Astrophysics Data System (ADS)
Der Artikel besch‰ftigt sich zun‰chst mit dem derzeitigen und zuk¸nftigen Einsatz von Social Software in Unternehmen. Nach dem groþen Erfolg von Social Software im Web beginnen viele Unternehmen eigene Social Software-Initiativen zu entwickeln. Der Artikel zeigt die derzeit wahrgenommenen Einsatzmˆglichkeiten von Social Software im Unternehmen auf, erˆrtert Erfolgsfaktoren f¸r die Einf¸hrung und pr‰sentiert mˆgliche Wege f¸r die Zukunft. Nach der Diskussion des Spezialfalles Social Software in Unternehmen werden anschlieþend die globalen Trends und Zukunftsperspektiven des Web 2.0 in ihren technischen, wirtschaftlichen und sozialen Dimensionen dargestellt. Wie aus den besprochenen Haupttrends hervorgeht, wird die Masse an digital im Web verf¸gbaren Informationen stetig weiterwachsen. So stellt sich die Frage, wie es in Zukunft mˆglich sein wird, die Qualit‰t der Informationssuche und der Wissensgenerierung zu verbessern. Mit dem Einsatz von semantischen Technologien im Web wird hier eine revolution‰re Mˆglichkeit geboten, Informationen zu filtern und intelligente, gewissermaþen verstehende" Anwendungen zu entwerfen. Auf dem Weg zu einem intelligenten Web werden sich das Semantic Web und Social Software ann‰hern: Anwendungen wie Semantic Wikis, Semantic Weblogs, lightweight Semantic Web-Sprachen wie Microformats oder auch kommerzielle Angebote wie Freebase von Metaweb werden die ersten Vorzeichen einer dritten Generation des Webs sein.
Raabe, Alexander
DEM integrity monitor experiment (DIME) flight test results
NASA Astrophysics Data System (ADS)
This paper discusses flight test results of a Digital Elevation Model (DEM) integrity monitor. The DEM Integrity Monitor Experiment (DIME) was part of the NASA Synthetic Vision System (SVS) flight trials at Eagle-Vail, Colorado (EGE) in August/September, 2001. SVS provides pilots with either a Heads-down Display (HDD) or a Heads-up Display (HUD) containing aircraft state, guidance and navigation information, and a virtual depiction of the terrain as viewed 'from the cockpit'. SVS has the potential to improve flight safety by increasing the situational awareness (SA) in low to near zero-visibility conditions to a level of awareness similar to daytime clear-weather flying. This SA improvement not only enables low-visibility operations, but may also reduce the likelihood of Controlled Flight Into Terrain (CFIT). Because of the compelling nature of SVS displays high integrity requirements may be imposed on the various databases used to generate the imagery on the displays even when the target SVS application does not require an essential or flight-critical integrity level. DIME utilized external sensors (WAAS and radar altimeter) to independently generate a 'synthesized' terrain profile. A statistical assessment of the consistency between the synthesized profile and the profile as stored in the DEM provided a fault-detection capability. The paper will discuss the basic DIME principles and will show the DIME performance for a variety of approaches to Runways 7 and 25 at EGE. The monitored DEMs are DTED Level 0, USGS with a 3-arcsec spatial resolution, and a DEM provided by NASA Langley. The test aircraft was a Boeing 757-200.
Uijt de Haag, Maarten; Young, Steve D.; Sayre, Jonathon; Campbell, Jacob; Vadlamani, Ananth
Assessment of Digital Elevation Model (DEM) aggregation methods for hydrological modeling: Lake Chad basin, Africa
Digital Elevation Models (DEMs) are used to compute the hydro-geomorphological variables required by distributed hydrological models. However, the resolution of the most precise DEMs is too fine to run these models over regional watersheds. DEMs therefore need to be aggregated to coarser resolutions, affecting both the representation of the land surface and the hydrological simulations. In the present paper, six
Mathieu Le Coz; FranÁois Delclaux; Pierre Genthon; Guillaume Favreau
Comparison of the extracted DEMs in Heihe River upper and middle reaches
NASA Astrophysics Data System (ADS)
The Digital Elevation Model (DEM) are terrain elevations at regularly spaced horizontal intervals, i.e., an a grid of regularly spaced elevations. With the development of computing technology, the methods of data acquisition, data storage and data processing speed for DEMs get along well. Heihe river lies in the northwest of China and is a continental river. It roots from snow-ice and disappears in deserts. The drainage area is about 140,000 square kilometers and the river is the main water source for the living. The upper reaches are mountainous and the runoff is very important. The middle reaches are oasis. At present, many hydrological and ecological models are introduced. The catchment basin and stream network data acquired from DEMs are main input data for many surface hydrological models. So the quality and resolution of DEMs are significant. Software ENVI Version 4.2 furnishes with the DEMs Extraction Module. The paper compared several methods for extracting DEMs of the upper reaches. We extracted the elevation data from the ASTER---stereo images with the module and created the DEM. Secondly; we collected the DEM based on the contour map of Heihe river. The comparison of the DEMs quality was carried out between the DEM from the contour map, the DEM extracted by ENVI Version 4.2. To a certain extent, the DEM from Aster imagery can reflect the terrain and be used in hydrological models.
Chao, Zhenhua; Nan, Zhuotong; Li, Xin; Mao, Zhihua
Effects of lidar point density on bare earth extraction and DEM creation
Data density has a crucial impact on the accuracy of Digital Elevation Models (DEMs). In this study, DEMs were created from a high point-density LIDAR dataset using the bare earth extraction module in Quick Terrain Modeler. Lower point-density LIDAR collects were simulated by randomly selecting points from the original dataset at a series of decreasing percentages. The DEMs created from
Angela M. Puetz; R. Chris Olsen; Brian Anderson
Reconstructing Stellar DEMs from X-ray Spectra
NASA Astrophysics Data System (ADS)
The temperature distribution of Emission Measure is a powerful tool to characterize and understand the composition and physical structure of stellar coronae. Numerous methods have been proposed in the literature to compute the Differential Emission Measure (DEM) based on line fluxes measured from identifiable lines in high-resolution EUV and X-ray spectra. Here we describe a new and powerful method that we have developed to reconstruct DEMs that improves significantly on previous algorithms and further allows for incorporating atomic data errors into the calculations. Some notable features of our algorithm are: an ability to fit to either a selected subset of lines with measured fluxes or to perform a global fit to all lines over the full wavelength range of the instrument, to fully incorporate line blends, to obtain error bars to determine the significance of features seen in the reconstructed DEM, and to directly incorporate prior information such as atomic line sequences, known atomic data errors, systematic effects due to calibration uncertainties, etc. We use highly structured models to account for the mixing of the ion/temperature specific spectra, the mixing of continuum photons with those from the multitude of spectral lines, instrumental response, the effective area of the instrument, and background contamination. We introduce the statistical framework of data augmentation (e.g., EM algorithms and MCMC samplers), in which we treat photon count in each level of the hierarchical structure as missing data. We implement a multi-scale (wavelet-like) prior distribution to smooth the DEM, which gives us the flexibility to overcome lack of information especially with low count data. In this talk we provide several simulation studies with both high-count and low-count data to evaluate the proposed method. We also provide several DEM reconstruction results of the active star alpha Aur (Capella), and validate the method by comparing our results to previous estimates of the Capella DEMs. The authors gratefully acknowledge funding for this project partially provided by NSF grant DMS-01-04129 and by NASA Contract NAS8-39073 (Chandra X-ray Center).
Kang, H.; van Dyk, D.; Kashyap, V.; Connors, A.
Constructing DEM from characteristic terrain information using HASM method
NASA Astrophysics Data System (ADS)
In the construction of DEM, terrain features (e.g. valleys or stream lines, ridges, peaks, saddle points) are important for improving DEM accuracy and saw many applications in hydrology, precision agriculture, military trajectory planning, etc. HASM (High Accuracy Surface Modeling) is a method for surface modeling, which is based on the theory of surface. Presently, HASM is only used for scattered point's interpolation. So the work in this paper attempts to construct DEM based on the characteristic terrain information as stream lines and scattered points by HASM method. The course is described as the following steps. Firstly TIN (Triangulated Irregular Network) from the scattered points is generated. Secondly, each segment of the stream lines is well oriented to represent stream lines' flow direction, and a tree data structure (that has parent, children and brothers) is used to represent the whole stream lines' segments. A segment is a curve which does not intersect with other segments. A Water Course Flow (WCF) line is a set of segment lines connected piecewise but without overlapping or repetition, from the most upper reaches to the most lower reaches. From the stream lines' tree data structure, all the possible WCF lines are enumerated, and the start point and end point of each WCF lines is predicted from searching among the TIN. Thirdly, given a cell size, a 2-D matrix for the research region is built, and the values of the cells who were traversed by the stream lines by linear interpolation among each WCF lines. Fourthly, all the valued cells that were passed through by the stream line and that were from the scattered points are gathered as known scattered sampling points, and then HASM is used to construct the final DEM. A case study on the typical landform of plateau of China, KongTong gully of Dongzhi Plateau, Qingyang, Gausu province, is presented. The original data is manually vecterized from scanned maps 1:10,000, includes scattered points, stream lines, contour lines, precipitous cliff lines of a region of area about 4◊5 square km. For simplicity only the former two kinds of data sources are used. By Comparing with the result from stream-line-constrained TIN and hydrologically correct DEM construction method Thin plate Spline (TPS, that is implemented as command TopoToRaster in ArcGIS 9.0 and later version)through visual inspection, HASM gets a more desirable DEM and more reasonable integration of information of the terrain features. Finally, some challenges and future research about HASM is also given.
Song, Dunjiang; Yue, Tianxiang; Du, Zhengping; Wang, Qingguo
Development of parallel DEM for the open source code MFIX
The paper presents the development of a parallel Discrete Element Method (DEM) solver for the open source code, Multiphase Flow with Interphase eXchange (MFIX) based on the domain decomposition method. The performance of the code was evaluated by simulating a bubbling fluidized bed with 2.5 million particles. The DEM solver shows strong scalability up to 256 processors with an efficiency of 81%. Further, to analyze weak scaling, the static height of the fluidized bed was increased to hold 5 and 10 million particles. The results show that global communication cost increases with problem size while the computational cost remains constant. Further, the effects of static bed height on the bubble hydrodynamics and mixing characteristics are analyzed.
Gopalakrishnan, Pradeep; Tafti, Danesh
Incorporating Atomic Data Errors in Stellar DEM Reconstruction
NASA Astrophysics Data System (ADS)
We develop a powerful new method to reconstruct stellar Differential Emission Measures (DEMs) its Bayesian framework allows us to incorporate atomic and calibration errors as prior information. For instance, known errors in the line locations, as well as lines missing from the atomic data base, can be included directly during fitting. Highly correlated systematic errors in the ion balance may be included as well, as a natural sequence during Monte Carlo sampling. Our method uses the statistical framework of data augmentation, where we treat photon counts in each level of a hierarchical structure as missing data. We demonstrate our method by fitting a selected subset of emission lines and continuum in Chandra and EUVE data of Capella to estimate the DEM that best describes the data, and simultaneously determine the element abundances. The Markov Chain Monte Carlo based method also naturally produces error estimates on the fit parameters.
Kang, Hosung; van Dyk, David A.; Kashyap, Vinay L.; Connors, Alanna
This paper presents a DEM generation procedure based on optical (SPOT stereo) and radar (InSAR, interferometric SAR) data. The first part of the paper is focused on InSAR. The second one is concerned with the integration of optical and radar data. Two levels of integration are proposed: the SPOT data can support the InSAR procedure (in particular phase unwrapping) and
Michele Crosetto; Bruno Crippa
InSAR Operational and Processing Steps for DEM Generation
SUMMARY Digital Elevation Models (DEMs) are used in many applications in the context of earth sciences such as in topographic mapping, environmental modelling, rainfall-runoff studies, landslide hazard zonation, seismic source modelling, etc. During the last years multitude of scientific applications of Synthetic Aperture Radar Interferometry (InSAR) techniques have evolved. It has been shown that InSAR is an established technique of
Francis Ifeanyi OKEKE
BOREAS Regional DEM in Raster Format and AEAC Projection
NASA Technical Reports Server (NTRS)
This data set is based on the GTOPO30 Digital Elevation Model (DEM) produced by the United States Geological Survey EROS Data Center (USGS EDC). The BOReal Ecosystem-Atmosphere Study (BOREAS) region (1,000 km x 1000 km) was extracted from the GTOPO30 data and reprojected by BOREAS staff into the Albers Equal-Area Conic (AEAC) projection. The pixel size of these data is 1 km. The data are stored in binary, image format files.
Knapp, David; Verdin, Kristine; Hall, Forrest G. (Editor)
Unfallchirurgische Katastrophenhilfe nach dem Erdbeben in Haiti 2010 - Ein Erfahrungsbericht
ZusammenfassungÝÝDas Erdbeben in Haiti im Januar 2010 verursachte ¸ber 220.000 Tote und mehr als 300.000 Verletzte. Damit stellt es einen der\\u000a grˆþten Massenanf‰lle von Verletzten in der j¸ngeren Geschichte dar. уrzte ohne Grenzenì begann unmittelbar nach dem Beben\\u000a mit der medizinischen Nothilfe und baute seine Aktivit‰ten im Verlauf zum grˆþten Katastropheneinsatz in der Geschichte der\\u000a Organisation aus. Allein in den
M. Winter; I. Osmers; S. Krieger
Zerebrale Vaskulitis unter Gemcitabin
ZusammenfassungÝÝWir berichten ¸ber eine 50-j‰hrige Patientin mit einem Urothelkarzinom pT4acN0cM0 der Harnblase, bei der nach problemloser\\u000a Applikation des 1. Zyklus einer neoadjuvant intentionierten Chemotherapie mit Gemcitabin und Cisplatin im 2. Zyklus generalisierte\\u000a Krampfanf‰lle und ein ausgepr‰gtes hirnorganisches Psychosyndrom auftraten. In der MRT des Kopfes fand sich das Bild einer\\u000a zerebralen Vaskulitis. Der enge zeitliche Zusammenhang zwischen der Gemcitabin-Gabe und dem
P. Schmorl; A. Heer-Sonderhoff; R. Vosshenrich; S. Conrad
Generalization of DEM for terrain analysis using a compound method
NASA Astrophysics Data System (ADS)
This paper reports an investigation into the generalization of a grid-based digital elevation model (DEM) for the purpose of terrain analysis. The focus is on the method of restructuring the grid-based surface elevation data to form a triangulated irregular network (TIN) that is optimized to keep the important terrain features and slope morphology with the minimum number of sample points. The critical points of the terrain surface are extracted from the DEM based on their significance, measured not only by their local relief, but also by their importance in identifying inherent geomorphological and drainage features in the DEM. A compound method is proposed by integrating the traditional point-additive and feature-point methods to construct a drainage-constrained TIN. The outcome is then compared with those derived from other selected methods including filtering, point-additive or feature-point algorithms. The results show that the compound approach is capable of taking advantage of both point-additive and feature-point algorithms to maximally keep the terrain features and to maintain RMSE at an acceptable level, while reducing the elevation data points by over 99%. The analytical result also shows that the proposed method outperforms the compared methods with better control in retaining drainage features at the same level of RMSE.
Zhou, Qiming; Chen, Yumin
Efficient parallel CFD-DEM simulations using OpenMP
NASA Astrophysics Data System (ADS)
The paper describes parallelization strategies for the Discrete Element Method (DEM) used for simulating dense particulate systems coupled to Computational Fluid Dynamics (CFD). While the field equations of CFD are best parallelized by spatial domain decomposition techniques, the N-body particulate phase is best parallelized over the number of particles. When the two are coupled together, both modes are needed for efficient parallelization. It is shown that under these requirements, OpenMP thread based parallelization has advantages over MPI processes. Two representative examples, fairly typical of dense fluid-particulate systems are investigated, including the validation of the DEM-CFD and thermal-DEM implementation with experiments. Fluidized bed calculations are performed on beds with uniform particle loading, parallelized with MPI and OpenMP. It is shown that as the number of processing cores and the number of particles increase, the communication overhead of building ghost particle lists at processor boundaries dominates time to solution, and OpenMP which does not require this step is about twice as fast as MPI. In rotary kiln heat transfer calculations, which are characterized by spatially non-uniform particle distributions, the low overhead of switching the parallelization mode in OpenMP eliminates the load imbalances, but introduces increased overheads in fetching non-local data. In spite of this, it is shown that OpenMP is between 50-90% faster than MPI.
Amritkar, Amit; Deb, Surya; Tafti, Danesh
Evaluating TauDEM Delineated Stream Networks Against the National Hydrography Dataset
NASA Astrophysics Data System (ADS)
TauDEM is a computer program for delineating stream networks and watershed boundaries from Digital Elevation Model (DEM) raster data. To evaluate the quality of TauDEM output we have compared a TauDEM delineated stream network generated from a 10 meter USGS National Elevation Dataset (NED) DEM against the stream network of the USGS National Hydrography Dataset (NHD) using Hausdorff distance as a similarity metric. In general, the quality of the TauDEM output is very good, but we found two areas of difficulty. First, TauDEM uses only collecting area to determine the locations where streams start. It was not possible by varying this single parameter to match the stream start locations in NHD over the entire stream network. Second, The TauDEM stream network showed increased errors in areas of low slope. This appears to be a limitation of the vertical resolution and accuracy of the source DEM, and not a fundamental problem with TauDEM. This points to the utility of LiDAR and other high accuracy measurements when generating DEMs for hydrologic modeling of channels.
Steinke, R. C.; Ogden, F. L.; lai, W.
High-precision DEM reconstruction based on airborne LiDAR point clouds
NASA Astrophysics Data System (ADS)
Airborne LiDAR point clouds have become important data sources for DEM generation recently; however the problem of low precision and low efficiency in DEM production still exists. This paper proposes a new technical scheme for high-precision DEM production based on airborne LiDAR point clouds systematically. Firstly, an elevation and density analysis method is applied to filter out outliers. Secondly, ground points are detected by an improved filter algorithm based on the hierarchical smoothing method. Finally, feature lines are extracted by the planar surface fitting and intersecting method, and a simple data structure of feature lines preserved DEM is proposed to achieve reconstructing high accuracy DEM, combing feature lines with ground points. Experimental results show that the proposed scheme is able to compensate for deficiencies of existing DEM reconstruction techniques and can meet the needs of high precision DEM production based on LiDAR data.
Xu, Jingzhong; Kou, Yuan; Wang, Jun
3D DEM analyses of the 1963 Vajont rock slide
NASA Astrophysics Data System (ADS)
The 1963 Vajont rock slide has been modelled using the distinct element method (DEM). The open-source DEM code, YADE (Kozicki & DonzÈ, 2008), was used together with the contact detection algorithm proposed by Boon et al. (2012). The critical sliding friction angle at the slide surface was sought using a strength reduction approach. A shear-softening contact model was used to model the shear resistance of the clayey layer at the slide surface. The results suggest that the critical sliding friction angle can be conservative if stability analyses are calculated based on the peak friction angles. The water table was assumed to be horizontal and the pore pressure at the clay layer was assumed to be hydrostatic. The influence of reservoir filling was marginal, increasing the sliding friction angle by only 1.6?. The results of the DEM calculations were found to be sensitive to the orientations of the bedding planes and cross-joints. Finally, the failure mechanism was investigated and arching was found to be present at the bend of the chair-shaped slope. References Boon C.W., Houlsby G.T., Utili S. (2012). A new algorithm for contact detection between convex polygonal and polyhedral particles in the discrete element method. Computers and Geotechnics, vol 44, 73-82, doi.org/10.1016/j.compgeo.2012.03.012. Kozicki, J., & DonzÈ, F. V. (2008). A new open-source software developed for numerical simulations using discrete modeling methods. Computer Methods in Applied Mechanics and Engineering, 197(49-50), 4429-4443.
Weng Boon, Chia; Houlsby, Guy; Utili, Stefano
Pre-Conditioning Optmization Methods and Display for Mega-Pixel DEM Reconstructions
NASA Astrophysics Data System (ADS)
The Atmospheric Imaging Assembly (AIA) for the Solar Dynamics Observatory will provide an unprecedented rate of mega-pixel solar corona data. This hastens the need for faster differential emission measure (DEM) reconstruction methods, as well as scientifically useful ways of displaying this information for mega-pixel datasets. We investigate pre-conditioning methods, which optimize DEM reconstruction by making an informed initial DEM guess that takes advantage of the sharing of DEM information among the pixels in an image. In addition, we evaluate the effectiveness of different DEM image display options, including single temperature emission maps and time-progression DEM movies. This work is supported under contract SP02D4301R to the Lockheed Martin Corp.
Sette, A. L.; DeLuca, E. E.; Weber, M. A.; Golub, L.
A LBM-DEM solver for fast discrete particle simulation of particle-fluid flows
NASA Astrophysics Data System (ADS)
The lattice Boltzmann method (LBM) for simulating fluid phases was coupled with the discrete element method (DEM) for studying solid phases to formulate a novel solver for fast discrete particle simulation (DPS) of particle-fluid flows. The fluid hydrodynamics was obtained by solving LBM equations instead of solving the Navier-Stokes equation by the finite volume method (FVM). Interparticle and particle-wall collisions were determined by DEM. The new DPS solver was validated by simulating a three-dimensional gas-solid bubbling fluidized bed. The new solver was found to yield results faster than its FVM-DEM counterpart, with the increase in the domain-averaged gas volume fraction. Additionally, the scalability of the LBM-DEM DPS solver was superior to that of the FVM-DEM DPS solver in parallel computing. Thus, the LBM-DEM DPS solver is highly suitable for use in simulating dilute and large-scale particle-fluid flows.
Xiong, Qingang; Madadi-Kandjani, Ehsan; Lorenzini, Giulio
A seamless, high-resolution digital elevation model (DEM) of the north-central California coast
A seamless, 2-meter resolution digital elevation model (DEM) of the north-central California coast has been created from the most recent high-resolution bathymetric and topographic datasets available. The DEM extends approximately 150 kilometers along the California coastline, from Half Moon Bay north to Bodega Head. Coverage extends inland to an elevation of +20 meters and offshore to at least the 3 nautical mile limit of state waters. This report describes the procedures of DEM construction, details the input data sources, and provides the DEM for download in both ESRI Arc ASCII and GeoTIFF file formats with accompanying metadata.
Foxgrover, Amy C., Barnard, Patrick L.
Numerical Simulation of high velocity impact phenomenon by the Distinct Element Method (DEM)
NASA Astrophysics Data System (ADS)
The Distinct Element Method (DEM) is one of the particle methods and is generally applied to granular materials and incompressible elastic materials. DEM with elastic-plastic deformation is developed for simulations of shock loading phenomenon in condensed media, and is applied to problems with large deformations. DEM gives more stable results than Lagrangian Finite Difference or Finite Element Method. Numerical oscillations are reduced by the consideration of artificial viscosity. The hydrodynamic constitutive law is introduced to the DEM, and the dynamic behaviors of materials, such as metals and concretes, under high velocity impact phenomenon are well compared with experimental and other computational results.
Tsukahara, Yoko; Matsuo, Akiko; Tanaka, Katsumi
Near-automatic generation of lava dome DEMs from photos
NASA Astrophysics Data System (ADS)
Acquiring accurate digital elevation models (DEMs) of growing lava domes is critical for hazard assessment. However, most techniques require expertise and time (e.g. photogrammetry) or expensive equipment (e.g. laser scanning and radar-based techniques). Here, we use a photo-based approach developed within the computer vision community that offers the potential for near-automatic DEM construction using a consumer-grade digital camera and freely available software. The technique is based on a combination of structure-from-motion and multi-view stereo algorithms (SfM-MVS) and can generate dense 3D point clouds (millions of points) from multiple photographs of a scene taken from different positions. Processing is carried out by automated 'reconstruction pipeline' software downloadable from the internet, e.g. http://blog.neonascent.net/archives/bundler-photogrammetry-package/. Such reconstructions are initally un-scaled and un-oriented so additional software (http://www.lancs.ac.uk/ staff/jamesm/software/sfm_georef.htm) has been developed to permit scaling or full georeferencing. Although this step requires the presence of some control points or knowledge of scale within the scene, it does not have the relatively strict image acquisition and control requirements of traditional photogrammetry. For accuracy and to allow error analysis, georeferencing observations are made within the image set, rather than requiring feature matching within the point cloud. Here we demonstrate the results of using the technique for deriving 3D models of the Volc·n de Colima lava dome. 5 image sets have been collected by different people over a period of 12 months during overflights in a light aircraft. Although the resulting imagery is of variable quality for 3D reconstruction, useful data can be extracted from each set. Scaling and georeferencing is carried out using a combination of ortho-imagery (downloaded from Bing) and a few GPS points. Overall precisions are ~1 m and DEM qualities are sufficient to quantify dome loss and talus gain from small rockfall sites, as well as to highlight the structural evolution of the upper surface of the dome as it collapses.
James, M. R.; Varley, N.
Extraction of Hydrological Proximity Measures from DEMs using Parallel Processing
Land surface topography is one of the most important terrain properties which impact hydrological, geomorphological, and ecological processes active on a landscape. In our previous efforts to develop a soil depth model based upon topographic and land cover variables, we extracted a set of hydrological proximity measures (HPMs) from a Digital Elevation Model (DEM) as potential explanatory variables for soil depth. These HPMs may also have other, more general modeling applicability in hydrology, geomorphology and ecology, and so are described here from a general perspective. The HPMs we derived are variations of the distance up to ridge points (cells with no incoming flow) and variations of the distance down to stream points (cells with a contributing area greater than a threshold), following the flow path. These HPMs were computed using the D-infinity flow model that apportions flow between adjacent neighbors based on the direction of steepest downward slope on the eight triangular facets constructed in a 3 x 3 grid cell window using the center cell and each pair of adjacent neighboring grid cells in turn. The D-infinity model typically results in multiple flow paths between 2 points on the topography, with the result that distances may be computed as the minimum, maximum or average of the individual flow paths. In addition, each of the HPMs, are calculated vertically, horizontally, and along the land surface. Previously, these HPMs were calculated using recursive serial algorithms which suffered from stack overflow problems when used to process large datasets, limiting the size of DEMs that could be analyzed using that method to approximately 7000 x 7000 cells. To overcome this limitation, we developed a message passing interface (MPI) parallel approach for calculating these HPMs. The parallel algorithms of the HPMs spatially partition the input grid into stripes which are each assigned to separate processes for computation. Each of those processes then uses a queue data structure to order the processing of cells so that each cell is visited only once and the cross-process communications that are a standard part of MPI are handled in an efficient manner. This parallel approach allows analysis of much larger DEMs as compared to the serial recursive algorithms. In this paper, we present the definitions of the HPMs, the serial and parallel algorithms used in their extraction and their potential applications in hydrology, geomorphology and ecology.
Tesfa, Teklu K.; Tarboton, David G.; Watson, Daniel W.; Schreuders, Kimberly A.; Baker, Matthew M.; Wallace, Robert M.
Two Preliminary SRTM DEMs Within the Amazon Basin
NASA Astrophysics Data System (ADS)
Digital topography provides important measures, such as hillslope lengths and flow path networks, for understanding hydrologic and geomorphic processes (e.g., runoff response to land use change and floodplain inundation volume). Two preliminary Shuttle Radar Topography Mission digital elevation models of Manaus (1S to 5S and 59W to 63W) and Rondonia (9S to 12S and 61W to 64W) were received from NASA JPL in August 2002. The "PI Processor" produced these initial DEM segments and we are using them to assess the initial accuracy of the interferometrically derived heights and for hydrologic research. The preliminary SRTM derived absolute elevations across the Amazon floodplain in the Cabaliana region generally range from 5 to 15 m with reported errors of 1 to 3 m. This region also includes some preliminary elevations that are erroneously negative. However, topographic contours on 1:100,000 scale quadrangles of 1978 to 1980 vintage indicate elevations of 20 to 30 m. Because double-bounce travel paths are possible over the sparsely vegetated and very-flat 2400 sq-km water surface of the Balbina reservoir near Manaus, it serves to identify the relative accuracy of the SRTM heights. Here, cell-to-cell height changes are generally 0 to 1 m and changes across a ~100 km transect rarely exceed 3 m. Reported errors throughout the transect range from 1 to 2 m with some errors up to 5 m. Deforestation in Rondonia is remarkably clear in the C-band DEM where elevations are recorded from the canopy rather than bare earth. Here, elevation changes are ~30 m (with reported 1 to 2 m errors) across clear-cut areas. Field derived canopy heights are in agreement with this change. Presently, we are deriving stream networks in the Amazon floodplain for comparison with our previous network extraction from JERS-1 SAR mosaics and for hydrologic modeling.
Alsdorf, D.; Hess, L.; Melack, J.; Dunne, T.; Mertes, L.; Ballantine, A.; Biggs, T.; Holmes, K.; Sheng, Y.; Hendricks, G.
Spatial Descriptions and Comparisons of Intermap IFSAR and USGS DEM Errors
[Abstract] This paper reports two groups of GIS- and field-based experiments that were designed to describe ,and compare ,DEM data ,errors in a ,spatially explicit fashion. Two USGS map quadrangles in the Santa Monica Mountains, CA, and three,small ,watersheds ,within ,these ,quadrangles ,were ,used ,for ,these experiments. USGS 10 m ,DEMs and ,Intermap 5 m ,IFSAR (interferometric synthetic aperture radar)
Yongxin Deng
Assessment of Multi-source Remote Sensing DEMs with RTK-GPS and Levelling Surveys
High resolution digital elevation models (DEMs) have been used in many applications such as civic planning, military mapping and navigation, natural hazard risk assessment, to name only a few. It has been a long history of using photogrammetry and dense ground surveys to draw the contour lines of the terrain and create the elevation model. Nowadays high precision DEMs with
Hsing-Chung Chang
Integration of DEM, ETM+, Geologic, and Magnetic Data for Geological Investigations in the Jifara Plain, Libya
We used an integrated approach to constrain the geological structure of the Jifara Plain in northwest Libya. The analysis of surface data, including a digital elevation model (DEM), Landsat Enhanced Thematic Mapper Plus images, and geologic maps, was combined with subsurface data, including well logs and magnetic data. The DEM data were used for the identification of geological lineaments in
Nureddin M. Saadi; Essam Aboud; Koichiro Watanabe
Digital elevation model (DEM) of Cascadia, latitude 39N-53N, longitude 116W-133W
This report contains a 250-meter digital elevation model (DEM) for Cascadia (latitude 39N - 53N, longitude 116W - 133W), a region that encompasses the Cascade volcanic arc, the Cascadia subduction zone, and the Juan de Fuca Ridge system. The DEM is distributed as file cascdem.tar.gz (39 MB; 78MB uncompressed).
compiled by Haugerud, Ralph A.
Calculating the trajectories of triboelectrically charged particles using Discrete Element Modeling (DEM)
Theoretical and experimental work has been performed pursuant to incorporating electrostatic forces into a commercial Discrete Element Modeling (DEM) software package. This DEM software is used to model the trajectories of large numbers of particles for industrial applications and processes. Electrostatic forces due to the triboelectrification of the particles will be included in the model in addition to existing kinematic
Michael D. Hogue; Carlos I. Calle; Peter S. Weitzman; David R. Curry
For realistic modelling of digital elevation model (DEM) uncertainty, information on the amount and spatial configuration is needed. However, common DEM products are often distributed with global error figures at best. Where no higher accuracy reference data is available, assumptions have to be made about the spatial distribution of uncertainty, that are often unrealistic. In order to assess the impact
Felix Hebeler; Ross S. Purves
Effects of LIDAR Point Density on Bare Earth Extraction and DEM Creation.
National Technical Information Service (NTIS)
Data density has a crucial impact on the accuracy of Digital Elevation Models (DEMs). In this study, DEMs were created from a high point- density LIDAR dataset using the bare earth extraction module in Quick Terrain Modeler. Lower point-density LIDAR coll...
A. M. Puetz B. Anderson R. C. Olsen
This paper summarises first results of the study carrying out in the frame of the programme for co-operation between European Space Agency and Czech Republic. One part of the study concentrates on the evaluation and development of the application potential of the SAR interferometry technique for DEM generation in the Czech Republic. The only DEM currently available for the entire
Lubos Kucera
ppohDEM: Computational performance for open source code of the discrete element method
NASA Astrophysics Data System (ADS)
We investigate performance improvements for the discrete element method (DEM) used in ppohDEM. First, we use OpenMP and MPI to parallelize DEM for efficient operation on many types of memory, including shared memory, and at any scale, from small PC clusters to supercomputers. We also describe a new algorithm for the descending storage method (DSM) based on a sort technique that makes creation of contact candidate pair lists more efficient. Finally, we measure the performance of ppohDEM using the proposed improvements, and confirm that computational time is significantly reduced. We also show that the parallel performance of ppohDEM can be improved by reducing the number of OpenMP threads per MPI process.
Nishiura, Daisuke; Matsuo, Miki Y.; Sakaguchi, Hide
Establishing predictive capabilities of DEM - Verification and validation for complex granular processes
NASA Astrophysics Data System (ADS)
The discrete element method has been increasingly used to model granular processes of increasing complexity, from dry to wet to multiphase systems. Whilst DEM has been shown to produce qualitatively many of the complex phenomena observed in these complex granular systems, establishing the extent of the predictive capability of DEM model is still in its infancy. This summary paper discusses the need to develop verification and validation methodologies with regard to DEM computations. It proposes the need to first verify that a DEM code with its implemented mathematical model and computation algorithm is accurately reproducing the conceptual model and its solution, before validating to determine the degree to which the computational model accurately represent the physics being modelled. It also discusses the associated issue of data analysis to extract the parameters of interest from DEM particle scale data.
Ooi, Jin Y.
Weitere mitteilungen ¸ber die Aufspaltung eines Bastards zwischen Origanum majorana L. ? und Origanum vulgare L. ? in der F 2 und F 3 Generation
Zusammenfassung Im Herbst des Jahres 1923 fand Verfasser in einer Kultur franzˆsischen Majorans eine Pflanze von abweichendem Habitus, in welchem er einen spontanen Bastard zwischen Majoran und Dosten,Origanum majorana L. ? undOriganum vulgare L. ? erkannte. Der Bastard zeigte eine sehr gute Fruchtbarkeit, sodasz durch vegetative Vermehrung desselben im Jahre 1925 bereits eine so grosze Menge Samens gewonnen werden konnte,
Johann Appl
First 2 years of TanDEM-X mission: Interferometric performance overview
NASA Astrophysics Data System (ADS)
The TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) mission comprises two nearly identical satellites: TerraSAR-X (TSX, launched in June 2007), and TanDEM-X (TDX, launched in June 2010), which form an innovative and flexible single-pass radar interferometer. The primary objective of the mission is to generate a worldwide and consistent digital elevation model (DEM) with an unprecedented accuracy. After a calibration phase of the TDX satellite, which was performed during the first 3 months after its launch, the two satellites were brought into close formation to begin the bistatic commissioning phase. Then, in December 2010, TanDEM-X started the operational global DEM acquisition in bistatic configuration. During the last 2 years, dedicated analyses on test acquisitions as well as persistent monitoring of the interferometric performance have been carried out, which are the subject of this paper. Key quantities in estimating interferometric performance such as coherence, relative height error, and phase-unwrapping indicators are investigated, showing the outstanding capabilities of TanDEM-X. Then, the main focus is shifted to those critical areas which, for various reasons, have shown unsatisfactory data quality and therefore must be reacquired with optimized imaging geometries in order to fulfill the DEM accuracy requirements. Promising results have been obtained so far, and future strategies to handle the critical data are discussed. This paper will present an overview of the interferometric performance of TanDEM-X, based on investigations performed in the first 2 years of mission operation, and will include results from the bistatic commissioning phase until the end of the first global DEM acquisition.
Martone, Michele; Rizzoli, Paola; Br‰utigam, Benjamin; Krieger, Gerhard
The algorithm of creating contour lines based on DEM
NASA Astrophysics Data System (ADS)
Contour line is a closed curve that joined by points of the same elevation. This paper puts forward a new algorithm of creating contour line based on DEM, which uses the method of tracking the same elevation point to study the algorithm based on regular grid. This paper will be divided the algorithm of creating contour line into four sub-algorithms, namely: the algorithm of elevation comparison; the algorithm of calculating the same elevation point coordinates; the algorithm of tracking next point of the same elevation, the algorithm of tracking contour line. The algorithm of elevation comparison is mainly used in judging whether a contour line with appointed elevation passes through a side of the grid; the algorithm of calculating the same elevation point coordinates is used to calculate coordinates of contour lines across the grid's side; function of the algorithm of tracking next point of the same elevation is to track next point of the same elevation by following the trend of contour lines; the algorithm of tracking contour line aims in tracking coordinates of the point which has the equal value of elevation with the point in row x and column y.
Tang, Lihua; Xu, Ai-jun; Fang, Lu-ming
The research on automatically created contour's algorithm based on DEM
NASA Astrophysics Data System (ADS)
Contour line is a closed curve that joined by points of the same elevation. This paper puts forward a new algorithm of creating contour line based on DEM, which uses the method of tracking the same elevation point to study the algorithm based on regular grid. This paper will be divided the algorithm of creating contour line into four sub-algorithms, namely: the algorithm of elevation comparison, the algorithm of calculating the same elevation point coordinates, the algorithm of tracking next point of the same elevation, the algorithm of tracking contour line. The algorithm of elevation comparison is mainly used in judging whether a contour line with appointed elevation passes through a side of the grid; the algorithm of calculating the same elevation point coordinates is used to calculate coordinates of contour lines across the grid's side; function of the algorithm of tracking next point of the same elevation is to track next point of the same elevation by following the trend of contour lines; the algorithm of tracking contour line aims in tracking coordinates of the point which has the equal value of elevation with the point in row x and column y.
Xu, Aijun; Li, Qingquan
Penetration strength of coarse granular materials from DEM simulations
NASA Astrophysics Data System (ADS)
Field tests are widely used for soil characterization in geotechnical applications in spite of implementation difficulties. The light penetrometer test is a well-known testing tool for fine soils, but the physical interpretation of the output data in the case of coarse granular materials is far less evident. In fact, the data are considerably more sensitive to various parameters such as fabric structure, particles shape or the applied impact energy. In order to achieve a better understanding of the underlying phenomena, we performed a numerical study by means contact dynamics DEM simulations. We consider the penetration of a moving tip into a sample composed of irregular grain shapes and we analyze the influence of the driving velocity and applied energy on the penetration strength. We find that the latter grows with both the penetration rate and energy. Force fluctuations on the tip involve a jamming-unjamming process. The typology of contact network and inter-granular friction play a major role in the fluctuations and measured values of the cone penetration strength.
Quezada, Juan Carlos; Saussine, Gilles; Breul, Pierre; Radjai, Farhang
Evaluation of DEM generation accuracy from UAS imagery
NASA Astrophysics Data System (ADS)
The growing use of UAS platform for aerial photogrammetry comes with a new family of Computer Vision highly automated processing software expressly built to manage the peculiar characteristics of these blocks of images. It is of interest to photogrammetrist and professionals, therefore, to find out whether the image orientation and DSM generation methods implemented in such software are reliable and the DSMs and orthophotos are accurate. On a more general basis, it is interesting to figure out whether it is still worth applying the standard rules of aerial photogrammetry to the case of drones, achieving the same inner strength and the same accuracies as well. With such goals in mind, a test area has been set up at the University Campus in Parma. A large number of ground points has been measured on natural as well as signalized points, to provide a comprehensive test field, to check the accuracy performance of different UAS systems. In the test area, points both at ground-level and features on the buildings roofs were measured, in order to obtain a distributed support also altimetrically. Control points were set on different types of surfaces (buildings, asphalt, target, fields of grass and bumps); break lines, were also employed. The paper presents the results of a comparison between two different surveys for DEM (Digital Elevation Model) generation, performed at 70 m and 140 m flying height, using a Falcon 8 UAS.
Santise, M.; Fornari, M.; Forlani, G.; Roncella, R.
Investigation of the Critical State in Soil Mechanics Using DEM
The existence and uniqueness of the so-called critical state in soil mechanics is validated in our DEM simulations of irregular polygonal particles. For different particle shape characteristics, the critical state is independent of the initial stress and density conditions. We retain low stress levels, since we do not take into account the crushing of particles. In biaxial test simulations isotropic particles evolve toward a limiting state in which the system reaches a critical void ratio and deforms with constant volume, deviatoric stress, fabric anisotropy, and mechanical coordination number. The last one has been found to be the first variable to attain a critical value making possible for the rest of micro-and-macro-mechanical variables the convergence to the critical state. In periodic shear cell tests, for large shear deformations samples with anisotropic particles reach at the macro-mechanical level the same critical value for both shear force and void ratio. At the micro-mechanical level the components of the stress tensor, the fabric tensor and the inertia tensor of the particles also reach the same stationary state. By varying the aspect ratio of the particles we stated the strong influence of particle shape anisotropy on the parameters that the granular packing attained at the critical state.
Pena, Andres A. [Bilfinger Berger GmbH, Gustav-Nachtigal 3, 65915 Wiesbaden (Germany); ICP, University of Stuttgart, Pfaffenwaldring 27, D-70569 Stuttgart (Germany); Garcia-Rojo, Ramon [EPCOS, Avda. Jose Ortega y Gasset 173, 29006 Malaga (Spain); Alonso-Marroquin, Fernando [MoSCoS, School of Mathematics and Physics, University of Queensland, St. Lucia, Qld. 4067 (Australia); Herrmann, Hans J. [Departamento de Fisica, Universidade Federal do Ceara, 60451-970 Fortaleza, Ceara (Brazil); Computational Physics, IfB, HIF E12, ETH Hoenggerberg, CH-8093 Zuerich (Switzerland)
DEM-induced errors in developing a quasi-geoid model for Africa
NASA Astrophysics Data System (ADS)
Errors in digital elevation models (DEMs) will introduce errors in geoid and quasi-geoid models, via their use in interpolating free-air gravity anomalies and (in the case of the quasi-geoid) their use in computing the Molodensky G 1 term. The effects of these errors and those of datum shifts are assessed using three independent DEMs for a test region in South Africa. It is shown that these effects are significant and that it is important to choose the best-possible DEM for use in geoid and quasi-geoid modelling.
Merry, C. L.
The influence of slope profile extraction techniques and DEM resolution on 2D rockfall simulation
NASA Astrophysics Data System (ADS)
The development of advanced 3D rockfall modelling algorithms and tools during the last decade has allowed to gain insights in the topographic controls on the quality and reliability of rockfall simulation results. These controls include DEM resolution and roughness, and depend on the adopted rockfall simulation approach and DEM generation techniques. Despite the development of 3D simulations, the 2D modelling approach still remains suitable and convenient in some cases. Therefore, the accuracy of high-quality 3D descriptions of topography must be preserved when extracting slope profiles for 2D simulations. In this perspective, this study compares and evaluates three different techniques commonly used to extract slope profiles from DEM, in order to assess their suitability and effects on rockfall simulation results. These methods include: (A) an "interpolated shape" method (ESRI 3D Analyst), (B) a raw raster sampling method (EZ Profiler), and (C) a vector TIN sampling method (ESRI 3D Analyst). The raster DEMs used in the study were all derived from the same TIN DEM used for method C. For raster DEM, the "interpolated shape" method (A) extracts the profile by bi-linear interpolating the elevation among the four neighbouring cells at each sampling location along the profile trace. The EZ Profiler extension (B) extracts the profile by sampling elevation values directly from the DEM raster grid at each sampling location. These methods have been compared to the extraction of profiles from TIN DEM (C), where slope profile elevations are directly obtained by sampling the TIN triangular facets. 2D rockfall simulations performed using a widely used commercial software (RocfallTM) with the different profiles show that: (1) method A and C provide similar results; (2) runout simulated using profiles obtained by method A is usually shorter than method C; (3) method B presents abrupt horizontal steps in the profiles, resulting in unrealistic runout. To study the influence of DEM resolution on rockfall simulation, profiles have been extracted from 1m, 5m, 10m and 15m gridded DEMs. The 2D rockfall simulations with the different resolution show that: (1) the effect of different resolution depends on topographic characteristics of the slope (e.g., steep or flat); (2) for steep slopes the rockfall motion is dominated by bouncing, and the coarser DEMs result in lower bouncing and lower kinematic energies and velocities; (3) for flat slopes, the motion is dominated by rolling and sliding, and the effect is the opposite: the coarser the DEM, the longer the runout.
Wang, X.; Frattini, P.; Agliardi, F.; Crosta, G. B.
Morphological changes at Mt. Etna detected by TanDEM-X
NASA Astrophysics Data System (ADS)
We produced a DEM of the Mt. Etna volcano using TanDEM-X data collected on October 9, 2012. The TanDEM-X data were acquired in bistatic mode with TSX as master sensor and TDX as receive only sensor. The pre-existing SRTM DEM was used for geometrical reference (geocoding, initial height model, large scale reference). The interferogram was computed with 4 looks in range and 4 looks in azimuth. After compensation of the SRTM heights, the differential TanDEM-X interferogram looked overall quite flat but showed local deviations related to noise (e.g. over the sea), topographic effects related to the low resolution of the SRTM DEM, and deviations related to actual changes of the topography, as observed in the Mount Etna peak region. After phase unwrapping, addressed with a minimum-cost flow algorithm and slight spatial filtering, the unwrapped phases were converted to relative heights. In order to move to absolute heights the SRTM height reference was used under the assumption that the deviation from the SRTM DEM is zero at large scale and without any linear trend. Finally, the height model was resampled into geographical coordinates. In the framework of the MED-SUV project, and thanks to the availability of a dense GPS network of more than 100 benchmarks periodically measured by INGV_OE, the TanDEM-X model has been validated. By computing the difference of the elevations provided by TanDEM-X with those measured by GPS we obtained a mean difference of 0.7 m and a standard deviation of 5.2 m. These values are biased by a few GPS benchmarks located in steep areas unfavorable illuminated by the radar. Without considerations of the two more unfavorable GPS stations, the height mean difference and a standard deviation are 0.6 m and 4.3 m respectively. We also performed correlation analyses of the height differences with respect to topography, latitude and longitude and we could exclude any elevation-related errors or geometrical ramp distortions. In the following, we compared the 2012 TanDEM-X model with the 2000 SRTM DEM in order to evaluate the morphological changes occurred on the volcano during the 12 years time lap. The pixel size of SRTM-DEM is about 90 m and we resampled the TanDEM-X model to fit this value. The results show that most of the variations occurred in the Valle del Bove and on the summit crater areas. In order to compare DEMs with the same pixel size, we performed a further comparison with a 5m ground resolution optical DEM, produced in 2004 and covering only the summit area. The variations in topography have been compared with ground mapping surveys, confirming a good correlation with the spatial extension of the lava flows and of the pyroclastic deposits occurred on Mt. Etna in the last seven years. The comparison between the two DEM's (2004-2012) allows calculating the amount of volcanics emitted and to clearly monitoring the growth and development of the New South East Crater (NSEC). TanDEM-X is a useful tools to monitor volcanic area characterized by a quit frequent activity (a paroxysm every 5-10 days), such us Mt. Etna, especially if concentrated in areas not easily accessible.
Wegmuller, Urs; Bonforte, Alessandro; De Beni, Emanuela; Guglielmino, Francesco; Strozzi, Tazio
HELI-DEM portal for geo-processing services
NASA Astrophysics Data System (ADS)
HELI-DEM (Helvetia-Italy Digital Elevation Model) is a project developed in the framework of Italy/Switzerland Operational Programme for Trans-frontier Cooperation 2007-2013 whose major aim is to create a unified digital terrain model that includes the alpine and sub-alpine areas between Italy and Switzerland. The partners of the project are: Lombardy Region, Piedmont Region, Polytechnic of Milan, Polytechnic of Turin and Fondazione Politecnico from Italy; Institute of Earth Sciences (SUPSI) from Switzerland. The digital terrain model has been produced by integrating and validating the different elevation data available for the areas of interest, characterized by different reference frame, resolutions and accuracies: DHM at 25 m resolution from Swisstopo, DTM at 20 m resolution from Lombardy Region, DTM at 5 m resolution from Piedmont Region and DTM LiDAR PST-A at about 1 m resolution, that covers the main river bed areas and is produced by the Italian Ministry of the Environment. Further results of the project are: the generation of a unique Italian Swiss geoid with an accuracy of few centimeters (Gilardoni et al. 2012); the establishment of a GNSS permanent network, prototype of a transnational positioning service; the development of a geo-portal, entirely based on open source technologies and open standards, which provides the cross-border DTM and offers some capabilities of analysis and processing through the Internet. With this talk, the authors want to present the main steps of the project with a focus on the HELI-DEM geo-portal development carried out by the Institute of Earth Sciences, which is the access point to the DTM outputted from the project. The portal, accessible at http://geoservice.ist.supsi.ch/helidem, is a demonstration of open source technologies combined for providing access to geospatial functionalities to wide non GIS expert public. In fact, the system is entirely developed using only Open Standards and Free and Open Source Software (FOSS) both on the server side (services) and on the client side (interface). In addition to self developed code the system relies mainly on teh software GRASS 7 [1], ZOO-project [2], Geoserver [3] and OpenLayers [4] and the standards WMS [5], WCS [6] and WPS [7]. At the time of writing, the portal offers features like profiling, contour extraction, watershed delineation and analysis, derivatives calculation, data extraction, coordinate conversion but it is evolving and it is planned to extend to a series of environmental modeling that the IST developed in the past like dam break simulation, landslide run-out estimation and floods due to landslide impact in artificial basins. [1] Neteler M., Mitasova H., Open Source GIS: A GRASS GIS Approach. 3rd Ed. 406 pp, Springer, New York, 2008. [2] Fenoy G., Bozon N., Raghavan V., ZOO Project: The Open Wps Platform. Proceeding of 1st International Workshop on Pervasive Web Mapping, Geoprocessing and Services (WebMGS). Como, http://www.isprs.org/proceedings/XXXVIII/4-W13/ID_32.pdf, 26-27 agosto 2010. [3] Giannecchini S., Aime A., GeoServer, il server open source per la gestione interoperabile dei dati geospaziali. Atti 15a Conferenza Nazionale ASITA. Reggia di Colorno, 15-18 novembre 2011. [4] Perez A.S., OpenLayers Cookbook. Packt Publishing, 2012. ISBN 1849517843. [5] OGC, OpenGIS Web Map Server Implementation Specification, http://www.opengeospatial.org/standards/wms, 2006. [6] OGC, OGC WCS 2.0 Interface Standard - Core, http://portal.opengeospatial.org/files/?artifact_id=41437, 2010b. [7] OGC, OpenGIS Web Processing Service, http://portal.opengeospatial.org/files/?artifact_id=24151, 2007.
Cannata, Massimiliano; Antonovic, Milan; Molinari, Monia
Automated sinkhole detection using a DEM subsetting technique and fill tools at Mammoth Cave National Park
NASA Astrophysics Data System (ADS)
An automated workflow for sinkhole detection is developed using Light Detection and Ranging (Lidar) data from Mammoth Cave National Park (MACA). While the park is known to sit within a karst formation, the generally dense canopy cover and the size of the park (~53,000 acres) creates issues for sinkhole inventorying. Lidar provides a useful remote sensing technology for peering beneath the canopy in hard to reach areas of the park. In order to detect sinkholes, a subsetting technique is used to interpolate a Digital Elevation Model (DEM) thereby reducing edge effects. For each subset, standard GIS fill tools are used to fill depressions within the DEM. The initial DEM is then subtracted from the filled DEM resulting in detected depressions or sinkholes. Resulting depressions are then described in terms of size and geospatial trend.
Wall, J.; Bohnenstiehl, D. R.; Levine, N. S.
2D DEM model of sand transport with wind interaction
NASA Astrophysics Data System (ADS)
The advance of the dunes in the desert is a threat to the life of the local people. The dunes invade houses, agricultural land and perturb the circulation on the roads. It is therefore very important to understand the mechanism of sand transport in order to fight against desertification. Saltation in which sand grains are propelled by the wind along the surface in short hops, is the primary mode of blown sand movement [1]. The saltating grains are very energetic and when impact a sand surface, they rebound and consequently eject other particles from the sand bed. The ejected grains, called reptating grains, contribute to the augmentation of the sand flux. Some of them can be promoted to the saltation motion. We use a mechanical model based on the Discrete Element Method to study successive collisions of incident energetic beads with granular packing in the context of Aeolian saltation transport. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyze the features of the consecutive collision processes made by the transport of the saltating disks by a wind in which its profile is obtained from the counter-interaction between air flow and grain flows. We used a molecular dynamics method known as DEM (soft Discrete Element Method) with a initial static packing of 20000 2D particles. The dilation of the upper surface due to the consecutive collisions is responsible for maintaining the flow at a given energy input due to the wind.
Oger, L.; Valance, A.
Study on the tie point selection for DEM extraction from stereo PRISM images
NASA Astrophysics Data System (ADS)
The accuracy of DEM extraction was analyzed from the view of tie point selection in the stereo ALOS/PRISM images, using PCI Geomatica software. In the analysis we considered three different parameters in the automatic tie point selection, namely, 1) the number of tie points, 2) the image correlation coefficient of tie points, and 3) the spatial resolution of DEM extraction. We found that a better DEM extraction accuracy was possible when we adopted a single tie point with large image correlation coefficient (around 0.8) and the spatial resolution of 2.5 (m) in the automatic tie point selection from the stereo PRISM images. In addition, we examined the dependence of the DEM extraction accuracy on the tie point's elevation in the manual tie point selection. However, no clear dependence on the tie point's elevation was found because of large DEM noises at tie points in the mountain area. Finally, some preliminary analysis results of DEM extraction accuracy were presented from the stereo QuickBird images.
Kawata, Yoshiyuki; Funatsu, Yukihiro; Yoshii, Satoshi; Takemata, Kazuya
Effects of BSO and DEM on thiol-level and radiosensitivity in HeLa cells
Reduction of the intracellular GSH and NPSH levels in HeLa cells by BSO and DEM treatments was determined. As parameters for radiation damage, single and double strand DNA breaks (ssb and dsb) and cell killing were used. Furthermore, repair of ssb and dsb were followed in the first 30 and 120 min after radiation, respectively. BSO and DEM treatment gave a small sensitization for the 3 types of radiation damage (ssb, dsb and cell killing) in aerobic condition. In hypoxic condition the sensitizing effect of both compounds on dsb was larger than the effect on ssb. Pretreatment with BSO and DEM had no influence on repair of ssb and dsb when cells were irradiated in air, but when cells were irradiated in hypoxia, repair was somewhat inhibited after pretreatment with DEM. It can be postulated that a reduction of the intracellular GSH level by BSO and DEM treatment affects cellular radiosensitivity both by a competitive mechanism between GSH and O/sub 2/ and by inhibition of enzymatic repair of DNA breaks, the latter only in the case of DEM treatment.
Vos, O.; Van Der Schans, G.P.; Roos-Verhey, W.S.D.
Crucial Points of Interferometric Processing for dem Generation Using High Resolution SAR Data
NASA Astrophysics Data System (ADS)
Data collection for digital elevation model (DEM) generation can be carried out by two main methods in space-borne remote sensing such as stereoscopy using optical or radar satellite imagery (stereophotogrammetry, respectively radargrammetry) and interferometry based on interferometric synthetic aperture radar (InSAR) data. These techniques have advantages and disadvantages in comparison against each other. Especially filling the gaps which arise from the problem of cloud coverage in DEM generation by optical imagery, InSAR became operational in recent years and DEMs became the most demanded interferometric products. Essentially, in comparison, DEM generation from synthetic aperture radar (SAR) images is not a simple manner like generation from optical satellite imagery. Interferometric processing has several complicated steps for the production of a DEM. The quality of the data set and used software package come into prominence for the stability of the generated DEM. In the paper, the interferometric processing steps for DEM generation from InSAR data and the crucial threshold values are tried to be explained. For DEM generation, a part of Istanbul (historical peninsula and near surroundings) was selected as the test field because of data availability. The data sets of two different imaging modes (StripMap ~ 3 m resolution and High Resolution Spotlight ~ 1 m resolution) of TerraSAR-X have been used. At the implementation, besides the determination of crucial points at interferometric processing steps, to define the effect of computer software, DEM production have been performed using two different software packages in parallel and the products have been compared In the result section of the paper, besides the colorful visualizations of final products along with the height scales, accuracy evaluations have been performed for both DEMs with the help of a more accurate reference digital terrain model (DTM). This reference model has been achieved by large scale aerial photos. Normally, it has a 5 m original grid spacing, however it has been resampled at a spacing of 1 m towards the needs of the research.
Sefercik, U. G.; Dana, I.
ALOS DEM quality assessment in a rugged topography, A Lebanese watershed as a case study
NASA Astrophysics Data System (ADS)
Deriving the morphometric descriptors of the Earth's surface from satellite images is a continuing application in remote sensing, which has been distinctly pushed with the increasing availability of DEMs at different scales, specifically those derived from high to very high-resolution stereoscopic and triscopic image data. The extraction of the morphometric descriptors is affected by the errors of the DEM. This study presents a procedure for assessing the quality of ALOS DEM in terms of position and morphometric indices. It involves evaluating the impact of the production parameters on the altimetric accuracy through checking height differences between Ground Control Points (GCP) and the corresponding DEM points, on the planimetric accuracy by comparing extracted drainage lines with topographic maps, and on the morphometric indices by comparing profiles extracted from the DEM with those measured on the field. A twenty set of triplet-stereo imagery from the PRISM instrument on the ALOS satellite has been processed to acquire a 5 m DEM covering the whole Lebanese territories. The Lebanese topography is characterized by its ruggedness with two parallel mountainous chains embedding a depression (The Bekaa Valley). The DEM was extracted via PCI Geomatica 2013. Each of the images required 15 GCPs and around 50 tie points. Field measurements was carried out using differential GPS (Trimble GeoXH6000, ProXRT receiver and the LaserACE 1000 Rangefinder) on Al Awali watershed (482 km2, about 5% of the Lebanese terrain). 3545 GPS points were collected at all ranges of elevation specifying the Lebanese terrain diversity, ranging from cliffy, to steep and gently undulating terrain along with narrow and wide flood plains and including predetermined profiles. Moreover, definite points such as road intersections and river beds were also measured in order to assess the extracted streams from the DEM. ArcGIS 10.1 was also utilized to extract the drainage network. Preliminary results showed that using Toutin's Model, enabling Wallis filter and specifying high DEM detail, along with restricting the holes filling option gave the best position accuracy and the least number of failure values. This is mainly due to the ruggedness of the studying area. Comparing GPS heights with the extract DEM showed a Minimum and a maximum error of (-11.9 m, 10.56 m), Mean error (1.32 m) and RMSE of (4.7 m). While extracting the drainage lines showed 80 to 90 % of coincidence of the upper water heads and an order of less than one pixel for the main river course and mountainous road intersection.
Abdallah, Chadi; El Hage, Mohamad; Termos, Samah; Abboud, Mohammad
Recent Release of the ASTER Global DEM Product
NASA Astrophysics Data System (ADS)
On June 29th, the ASTER Global Digital Elevation Model (DEM) release was announced to the public and to a very eager audience. ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an imaging instrument flying on Terra, a satellite launched in December 1999 as part of NASA's Earth Observing System (EOS). ASTER is a cooperative effort between NASA, Japan's Ministry of Economy, Trade and Industry (METI) and Japan's Earth Remote Sensing Data Analysis Center (ERSDAC). On June 21, NASA Headquarters along with colleagues in Japan (METI) signed a plan for distribution of this product. The global digital elevation model of Earth is available online to users everywhere at no cost from NASA's Land Processes Distributed Active Archive Center (DAAC) located at Sioux Falls, SD. The DAAC is a joint project of NASA and the USGS and is a key component of NASA's EOSDIS. The new ASTER GDEM was created from nearly 1.3 million individual stereo-pair images acquired by the Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer (Aster) instrument aboard NASAís Terra satellite. The ASTER elevation model was jointly developed by NASA and METI under contract to Sensor Information Laboratory Corp., Tsukuba, Japan. On June 29, the NASA press release was picked up quickly by numerous news organizations and online sites. Response to the product was incredible! The news of the release of the product was carried on websites across the globe, this fueled a tremendous response from users. Here are a few interesting metrics about the release: - over 41,000 unique visitors to website in first week following release - top countries in order were: US (approx. 20%), Germany, U.K., Brazil, Austria, Canada, Spain, Switzerland, Japan - approximately 29,000 visitors came to the news page in the first week and about 11,000 of these users downloaded the actual press release - by the end of August, over 2 Million ASTER GDEM files had been downloaded from the Land Processes DAAC This presentation covers the issues associated with the release of this very popular product, including issues raised by many of our users.
Behnke, J.; Hall, A.; Meyer, D.; Sohre, T.; Doescher, C.
The generation of DEM from ALOS/PRISM and ice volume change in Mt. Qomolangma region
NASA Astrophysics Data System (ADS)
Calculation on glacier volume variations are still greatly limited by the vertical accurate of various data sources till now (Stevens et al., 2004). Therefore, one of the major methodological gaps in the observation of glaciers from space is the measurement of glacier volume changes (K‰‰b, 2008). Glacier volume changes needs an integrated study and correction on generated DEMs from multi-sources remote sensing data and evaluation of the vertical errors and accuracy. Here, we produced DEMs over mountain glaciers from ASTER and ALOS/PRISM on the northern slope of Mt. Qomolangma (hereafter called the Mt. Qomolangma region), also known as the Mt. Everest, located in the middle Himalayan Mountains, 27∞ 59-28∞ 11¥N and 86∞ 44¥- 86∞ 59¥E. A series of digital images, include Aster images on 23 Oct 2003, ALOS/AVNIR-2 on 19 Jan 2007, ALOS/AVNIR-2 on 24 Oct 2008, 3 scenes of ALOS/PRISM on 04 Dec 2006, 1:50,000 topographic maps with contour interval of 20 m produced from aerial photographs acquired in 1974 and the 1:50,000 DEM (cell size: 25 m) generated from the topographic maps were used. The DEM was generated based on the three scenes from ALOS/PRISM images and PCI Orthoengine module. The process of DEM generation from ASTER images is very similar to that of ALOS/PRISM. The difference is that: only two images ASTER from nadir and backward views were used here. Table 1 The differences between generated DEMs and the 1:50,000 topographic maps in the non-glacierized area dem5wdemasterprism12_50mprism13_50mprism14_25mprism15_100mSRTM DEMASTER_GDEM Maximum 80.0 920.0 218.0 174.0 258.0 168.0 240.0 437.0 Minimum -123.0 -331.0 -297.0 -367.0 -459.0 -393.0 -315.0 -182.0 aveDEV 23.8 84.0 33.9 36.0 31.3 45.9 67.6 57.9 AVERAGE6.9 75.3 11.3 5.9 1.7 17.2 32.3 45.0 StDEV 30.5 128.0 55.7 59.4 60.6 64.4 85.8 77.2 RMSe 31.2 148.3 56.7 59.6 60.5 66.5 91.5 89.2 Compared various kinds of products of the generated DEMs in the non-glacierized area with the 1:50,000 topographic maps using 215 random points, we found that the mean difference of PRISM DEM to the topographic maps is 1.7 m. However, the mean difference of ASTER GDEM (ASTER_GDEM) is 45m, which is released Version 1 of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) on 29 June, 2009. Our result shows that the quality of ALOS/PRISM DEM is better than that of ASTER GDEM, and the calibrated ALOS/PRISM DEM based on the relationship between aspect and DEM difference was more accurate than the original generated one. Fig.1 The generated ASTER DEM on 23 Oct 2003 Fig.2 the generated PRISM DEM on 04 Dec 2006
Ye, Qinghua
Volume changes during the 2010 Merapi eruption calculated from TanDEM-X interferometry
NASA Astrophysics Data System (ADS)
Estimating the amount of erupted material during a volcanic crisis is one of the major challenges in volcano research. One way to do this and to discriminate between juvenile and non-juvenile fraction is to assess topographic changes before and after an eruption while using area-wide 3D data. LiDAR or other airborne systems may be a good source, but the recording fails when clouds due to volcanic activity obstruct the sight. In addition, costs as well as logistics for local observatories are high. When dealing with dome-building volcanoes, acquiring the data gets further complicated. As the volcano dome can change rapidly in active phases, it is nearly impossible to collect data at the right time. However, when dealing with gross volume change estimates, at least two data sets - taken directly before and after the eruption - are essential. The innovative bistatic German Earth observation mission TanDEM-X is of great importance to overcome some of these problems. Two almost identical radar satellites TerraSAR-X and TanDEM-X fly in a close formation, taking pictures of the same place on the Earth surface at the same time (bistatic mode). This results in two nearly absolutely coherent images. As the radar signal penetrates clouds, digital elevation models (DEMs) of the area of investigation can be generated without problems even with cloud cover. A time series analysis of the DEMs derived in bistatic mode therefore opens the possibility to assess volume changes at active dome-building volcanoes. We analyze the volume changes due to the hazardous Merapi eruption in 2010. The eruption started on October 26, 2010. During the eruption, the 2006 lava dome was destroyed. A new lava dome was built and destroyed again at the end of the eruption in November 2010. We show a series of DEMs derived from Merapi by TanDEM-X SAR-interferometry taken before and after the 2010 eruption. The bistatic SAR images are acquired from ascending as well as descending orbits highlighting the NE-SE and NW-SW sectors of the edifice, respectively. We use the DEMs to give values of the volume change at the summit caused by the 2010 eruption. As the TanDEM-X mission is an innovative mission, the present study serves as a test to employ data of a new satellite mission in volcano research. An error analysis of the DEMs to evaluate the volume quantifications was therefore also conducted.
Kubanek, Julia; Westerhaus, Malte; Heck, Bernhard
Generation an ideal DEM by fusion shape from shading and interferometry bathymetries for seafloor remote sensing
NASA Astrophysics Data System (ADS)
In sonar imaging for seafloor remote sensing, research activities are more and more oriented on the use of data fusion approaches. Nowadays, it is well established that using sonar images, the Digital Elevation Maps (DEMs), can be generated by exploiting either the amplitude information or the phase information of the acoustic signal. In this paper, the main interest consists on the generation of a complete Digital Elevation Map (DEM) by the use of a data fusion approach of two existing DEMs issued from two different techniques. The aim of the proposed approach is to elaborate a general interpretation system that coherently links works on data selection and fusion leading to improve DEMs generation and to exploit it in the seafloor remote sensing applications (particularly for the inhomogeneous scenes with a variety terrain). In this paper, shape from shading and the interferometry techniques are considered. Then, the manner of the DEMs fusion proposed, has been based on fuzzy logic and some fuzzy propositions, which defined using experts a priori knowledge source. This promising idea enables information to be managed through the consideration of the imprecision and ambiguity information and the benefit provide by the injection of the a priori knowledge in the decision taken system.
Abu Nokra, Nada M.; Lecornu, Laurent; Zerr, Benoit; Solaiman, Basel; Sintes, Christophe
Comparison of Low Altitude Photogrammetric Methods for Obtaining Dems and Orthoimages of Archaeological Sites
NASA Astrophysics Data System (ADS)
In this work it is performed a comparison of two methods for obtaining digital elevation models (DEMs) and orthoimages of medium-sized archaeological sites (500-5000 m2). The photogrammetric methods analyzed consist in the use of a light aerial platform applying the normal case of photogrammetry (vertical photographs and regular blocks), and the second one is based on a network of oblique photographs, taken from a telescopic mast, using a DEM obtained from a terrestrial laser scanner (TLS) survey. The main goal is to analyze the more efficient method for these studies taking into account variables such the working time, the accuracy obtained in the final products, the visual analysis of final orthoimages, etc. This study has been applied to the same archaeological site in two different epochs. The image acquisition was performed before and after a conservation intervention at the archaeological site. The results have shown similar characteristics for both products (DEMs and orthoimages) and accuracies but the density of DEMs and the visual analysis of orthoimages have shown differences that allows us to select the more adequate method taking into account the characteristics of each case. Thus the DEMs obtained using the TLS survey has shown more density of points while the visual analysis of orthoimages has shown a better behaviour (radiometrically and visually) in the case of vertical photographs.
Mozas-Calvache, A. T.; PÈrez-GarcÌa, J. L.; Cardernal-Escarcena, F. J.; Delgado, J.; Mata-deCastro, E.
Surface water hydrologic simulation of Qingshuijiang Watershed based on SRTM DEM
NASA Astrophysics Data System (ADS)
The Digital Elevation Model (DEM) derived from NASA's Shuttle Radar Topography Mission is the most accurate nearglobal elevation model that is publicly available. The characteristics, advantages, and disadvantages of Shuttle Radar Topography Mission (SRTM) data sets were reviewed and discussed briefly. In order to verify the effect of applying SRTM data sets in surface water hydrologic simulation, a tool set named Arc Hydro Tools that is utilized to extract watershed characteristics was introduced, developed as an ArcGIS interface. The Qingshuijiang watershed in Guizhou Province, Southwest China, was taken as a case study. Using the tool set, the river network and subwatersheds of main tributaries were delineated from CGIAR- CSI SRTM 90 m DEM. By comparing the river network delineated from CGIAR-CSI SRTM 90 m DEM with the actual river network and comparing areas of the subwatersheds delineated from CGIAR-CSI SRTM 90 m DEM with the actual areas of the subwatersheds, it can be concluded that the delineated river network is generally in accord with the actual river network, as well as the areas of the delineated subwatersheds. The CGIAR-CSI SRTM 90 m DEM will promote the use of geospatial science and applications for digital topography analysis, especially for surface water hydrologic simulation.
Tang, Congguo; Liu, Congqiang
DEM Extraction from High-Resolution Stereoscopic Worldview 1 & 2 Imagery of Polar Outlet Glaciers
NASA Astrophysics Data System (ADS)
There are few reliable digital elevation models (DEMs) in polar regions and most are of low resolution (on the order of 100's of meters to km) or of poor quality. Polar environments are changing rapidly and accurate DEMs are critical for correcting imagery, measuring glacier thickness changes and modeling ice flow and surface melt water drainage. Using in-track stereoscopic images from Worldview-1 and Worldview-2, we derived high-resolution DEMs for outlet glaciers and other areas of interest in Antarctica and the Arctic. We used ERDAS Imagine's LPS eATE (enhanced automated terrain extraction) algorithm to derive a dense point cloud of matches. The resulting point cloud is comparable in density to that obtained by LiDAR flown at 10,000 feet. Preliminary comparisons of our results to ground control points collected by field teams and airborne and satellite laser altimeters show 0.5 - 10 meter vertical error over glaciers and 2 - 10 meter error over ice-free terrain. The error is primarily due to approximations in the sensor model and is consistent across the DEM. Our results indicate that refinements in the sensor model and point matching algorithm will improve accuracy. Given the increasing interest in glacier change detection around the globe, DEMs extracted from frequent satellite stereo pairs can be used to monitor and quantify changes in both movement and volume.
Porter, C. C.; Morin, P. J.; Howat, I. M.; Niebuhr, S.; Smith, B. E.
Scale-dependent predictability of DEM-based landform attributes for soil spatial variability in a coastal dune system
Much soilñlandform modeling has shown that the predictability of topographic parameters derived from digital elevation models (DEM) for soil spatial variability is influenced by the selection of DEM's grid size. This study investigates soilñterrain relationships in a coastal dune at multiple DEM resolutions to examine if such scale-dependence is a ubiquitous phenomenon even in low-relief systems with relatively homogeneous substrates.
Daehyun Kim; Yanbing Zheng
Discrete Element Method (DEM) Application to The Cone Penetration Test Using COUPi Model
NASA Astrophysics Data System (ADS)
The cone penetration test (CPT) is a soil strength measurement method to determine the tip resistance and sleeve friction versus depth while pushing a cone into regolith with controlled slow quasi-static speed. This test can also be used as an excellent tool to validate the discrete element method (DEM) model by comparing tip resistance and sleeve friction from experiments to model results. DEM by nature requires significant computational resources even for a limited number of particles. Thus, it is important to find particle and ensemble parameters that produce valuable results within reasonable computation times. The Controllable Objects Unbounded Particles Interaction (COUPi) model is a general physical DEM code being developed to model machine/regolith interactions as part of a NASA Lunar Science Institute sponsored project on excavation and mobility modeling. In this work, we consider how different particle shape and size distributions defined in the DEM influence the cone tip and friction sleeve resistance in a CPT DEM simulation. The results are compared to experiments with cone penetration in JSC-1A lunar regolith simulant. The particle shapes include spherical particles, particles composed from the union of three spheres, and some simple polyhedra. This focus is driven by the soil mechanics rule of thumb that particle size and shape distributions are the two most significant factors affecting soil strength. In addition to the particle properties, the packing configuration of an ensemble strongly affects soil strength. Bulk density of the regolith is an important characteristic that significantly influences the tip resistance and sleeve friction (Figure 1). We discuss different approaches used to control granular density in the DEM, including how to obtain higher bulk densities, using numerical "shaking" techniques and varying the friction coefficient during computations.
Kulchitsky, A. V.; Johnson, J.; Wilkinson, A.; DeGennaro, A. J.; Duvoy, P.
Assessment of Digital Elevation Model (DEM) aggregation methods for hydrological modeling: Lake Chad basin, Africa
NASA Astrophysics Data System (ADS)
Digital Elevation Models (DEMs) are used to compute the hydro-geomorphological variables required by distributed hydrological models. However, the resolution of the most precise DEMs is too fine to run these models over regional watersheds. DEMs therefore need to be aggregated to coarser resolutions, affecting both the representation of the land surface and the hydrological simulations. In the present paper, six algorithms (mean, median, mode, nearest neighbour, maximum and minimum) are used to aggregate the Shuttle Radar Topography Mission (SRTM) DEM from 3? (90 m) to 5' (10 km) in order to simulate the water balance of the Lake Chad basin (2.5 Mkm 2). Each of these methods is assessed with respect to selected hydro-geomorphological properties that influence Terrestrial Hydrology Model with Biogeochemistry (THMB) simulations, namely the drainage network, the Lake Chad bottom topography and the floodplain extent. The results show that mean and median methods produce a smoother representation of the topography. This smoothing involves the removing of the depressions governing the floodplain dynamics (floodplain area<5000 km 2) but it eliminates the spikes and wells responsible for deviations regarding the drainage network. By contrast, using other aggregation methods, a rougher relief representation enables the simulation of a higher floodplain area (>14,000 km 2 with the maximum or nearest neighbour) but results in anomalies concerning the drainage network. An aggregation procedure based on a variographic analysis of the SRTM data is therefore suggested. This consists of preliminary filtering of the 3? DEM in order to smooth spikes and wells, then resampling to 5' via the nearest neighbour method so as to preserve the representation of depressions. With the resulting DEM, the drainage network, the Lake Chad bathymetric curves and the simulated floodplain hydrology are consistent with the observations (3% underestimation for simulated evaporation volumes).
Le Coz, Mathieu; Delclaux, FranÁois; Genthon, Pierre; Favreau, Guillaume
Quality assessment of Digital Elevation Model (DEM) in view of the Altiplano hydrological modeling
NASA Astrophysics Data System (ADS)
Topography is crucial data input for hydrological modeling but in many regions of the world, the only way to characterize topography is the use of satellite-based Digital Elevation Models (DEM). In some regions, the quality of these DEMs remains poor and induces modeling errors that may or not be compensated by model parameters tuning. In such regions, the evaluation of these data uncertainties is an important step in the modeling procedure. In this study, which focuses on the Altiplano region, we present the evaluation of the two freely available DEM. The shuttle radar topographic mission (SRTM), a product of the National Aeronautics and Space Administration (NASA) and the Advanced Space Born Thermal Emission and Reflection Global Digital Elevation Map (ASTER GDEM), data provided by the Ministry of Economy, Trade and Industry of Japan (MESI) in collaboration with the NASA, are widely used. While the first represents a resolution of 3 arc seconds (90m) the latter is 1 arc second (30m). In order to select the most reliable DEM, we compared the DEM elevation with high qualities control points elevation. Because of its large spatial coverture (track spaced of 30 km with a measure of each 172 m) and its high vertical accuracy which is less than 15 cm in good weather conditions, the Geoscience Laser Altimeter System (GLAS) on board on the Ice, Cloud and Land elevation Satellite of NASA (ICESat) represent the better solution to establish a high quality elevation database. After a quality check, more than 150 000 ICESat/GLAS measurements are suitable in terms of accuracy for the Altiplano watershed. This data base has been used to evaluate the vertical accuracy for each DEM. Regarding to the full spatial coverture; the comparison has been done for both, all kind of land coverture, range altitude and mean slope.
SatgÈ, F.; Arsen, A.; Bonnet, M.; Timouk, F.; Calmant, S.; Pilco, R.; Molina, J.; Lavado, W.; CrÈtaux, J.; HASM
Impact of Digital Elevation Model (DEM) Aggregation Methods on Watershed Properties for a Flat Regional Basin
NASA Astrophysics Data System (ADS)
Digital Elevation Models (DEMs) are widely used in hydrological modelling to describe the geomorphological variability of watersheds. However, due to limited computational and memory resources, the resolution of the most precise available DEMs is often too fine to run models over regional scales. DEMs therefore need to be aggregated to coarser resolutions, affecting the representation of the land surface. In the flat Lake Chad basin (2.5 M km2), six algorithms are assessed to aggregate the SRTM (Shuttle Radar Topography Mission) DEM from 3 sec (90 m), the resolution of the released product, to 5 min (10 km), a resolution directly usable by a regional hydrological model. The results show that the suitability of aggregation methods strongly depends on the hydrological entity under consideration. First, concerning Lake Chad bathymetry, the level-area and level-volume relationships are preserved with all the methods assessed except the minimum and maximum which distort the lake bottom topography. Second, regarding the drainage network, point oriented methods such nearest neighbour, minimum and maximum induce local channel capture effect. In contrast, methods which smooth the topography such mean and median result in a consistent river network representation. Third, in order to preserve the small depressions governing the floodplain dynamic, only the nearest neighbour and the maximum are relevant. Indeed, with these methods the simulated evaporated volume over the surface waters of the Lake Chad basin is close to the estimations, whereas with other methods it is importantly underestimated. So as to optimize the preservation of these three hydrological entities during the aggregation procedure, a double-step method is therefore proposed. The first step consists of a preliminary median filtering of the 3 sec DEM in order to smooth the very local variations in elevation including SRTM speckle artefacts. The filter window size (39 sec) corresponds to the average range of variograms computed over flat areas of the basin. In the second step, the filtered DEM is aggregated to 5 min via the nearest neighbour method. With the resulting DEM, the Lake Chad bathymetric curves are close to those extracted from the 3 sec DEM (RMS deviation < 3.5%) and there is no anomaly on the extracted drainage network. Moreover the simulated floodplain hydrology is consistent with estimations (3% underestimation for simulated evaporation volumes).
Le Coz, M.; Delclaux, F.; Genthon, P.; Favreau, G.
Morphometry and parameter assessment of scoria cones fields: a DEM-based morphometric approach
NASA Astrophysics Data System (ADS)
Cinder cones are relatively small but common volcanic features that form by the eruption of low-viscosity, generally basaltic magma during strombolian or hawaiian eruptions. Often they appear in volcanic fields, providing geomorphic evidence of a particular eruptive behaviour. Also, when a big number of scoria cones are scattered over a large area, it means that there the magma can find several different ways to reach the Earth's surface. These facts as well as the time-space distribution of the cones have important implications toward the understanding of local geological settings, and have substantial inferences for hazard assessment. The recent availability of freely downloadable topographic data increases the efficiency and precision of the collection of morphometric parameters of scoria cones. Various digital elevation models (DEMs) at different resolution can nowadays be found on the internet: the Shuttle Radar Topography Mission DEMs (SRTM; http://www2.jpl.nasa.gov/srtm); the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM; http://www.gdem.aster.ersdac.or.jp); the USGS National Elevation Dataset (NED; http://seamless.usgs.gov); TINITALY DEMs (http://kharita.rm.ingv.it); etc. Measurements of scoria cone characteristics using DEMs engage errors that are dependent on the DEM resolution and accuracy. The SRTM DEM was discarded because of the too low resolution. Obviously, the errors involved in scoria cone morphometry are also dependent on the cone dimensions. In this work we measured the discrepancies of the widely used morphometric parameters (V, H,Wco, and H/Wco) between DEMs from different sources (LIDAR = 2 m, TINITALY = 10 m, NED ~ 10 m, ASTER ~ 30 m) as a function of scoria cone volume, in order to assess the precision of these free available DEMs. As a result, we identified cone volume values, depending on resolution, beyond which the morphometric and volumetric measurements are reliable. Based on this assessment, scoria cones have been selected having well defined circular boundaries, no breaching, and being separated from the surrounding terrain by an abrupt change in slope. Using the created data base, cone height (Hco), cone width or basal diameter (Wco), and cone volume (V) have been calculated and compared for hundreds of cones, belonging to 32 cone field disseminated over the world. Some of the studied fields are well known, but for most of them we provide the first systematic results of scoria cone morphometry.
Fornaciai, Alessandro; Kar·tson, D·vid; Favalli, Massimiliano; Tarquini, Simone
Influence of Lossy Compressed DEM on Radiometric Correction for Land Cover Classification of Remote Sensing Images
NASA Astrophysics Data System (ADS)
World coverage Digital Elevation Models (DEM) have progressively increased their spatial resolution (e.g., ETOPO, SRTM, or Aster GDEM) and, consequently, their storage requirements. On the other hand, lossy data compression facilitates accessing, sharing and transmitting large spatial datasets in environments with limited storage. However, since lossy compression modifies the original information, rigorous studies are needed to understand its effects and consequences. The present work analyzes the influence of DEM quality -modified by lossy compression-, on the radiometric correction of remote sensing imagery, and the eventual propagation of the uncertainty in the resulting land cover classification. Radiometric correction is usually composed of two parts: atmospheric correction and topographical correction. For topographical correction, DEM provides the altimetry information that allows modeling the incidence radiation on terrain surface (cast shadows, self shadows, etc). To quantify the effects of the DEM lossy compression on the radiometric correction, we use radiometrically corrected images for classification purposes, and compare the accuracy of two standard coding techniques for a wide range of compression ratios. The DEM has been obtained by resampling the DEM v.2 of Catalonia (ICC), originally having 15 m resolution, to the Landsat TM resolution. The Aster DEM has been used to fill the gaps beyond the administrative limits of Catalonia. The DEM has been lossy compressed with two coding standards at compression ratios 5:1, 10:1, 20:1, 100:1 and 200:1. The employed coding standards have been JPEG2000 and CCSDS-IDC; the former is an international ISO/ITU-T standard for almost any type of images, while the latter is a recommendation of the CCSDS consortium for mono-component remote sensing images. Both techniques are wavelet-based followed by an entropy-coding stage. Also, for large compression ratios, both techniques need a post processing for correctly delimiting coastline, avoiding the confusion between elevation and no-data values. Six (from March 2005 to May 2007) geometrically corrected Landsat-5 images on the path-row 197-031 have been used. The six optical bands and the NDVI for each date have been introduced in a powerful hybrid classification process. The training areas and the ground truth have been obtained from the Mapa de Cobertes del SÚl de Catalunya (v. 3), a land cover map created by photointerpretation of 0.5 m orthophotomaps acquired between 2005 and 2007 and covering all the extension of Catalonia. The legend has been reduced from 233 categories to 21. Preliminary results have shown that the effect on land cover classification of applying lossy compression to the DEM used in the radiometric correction is small (lower than 1%) even for compression ratios up to 200:1. Comparing classification performance after a compression of 5:1 and and a compression of 200:1 with both coding standards showed that: a) the percentage of correctly classified image was 73%; b) 20% was wrongly classified; c) 3.5% was wrongly classified at compression ratio 5:1; and d) also 3.5% was wrongly classified at compression ratio 200:1. These results are the first in the literature to analyze the effect of DEM lossy compressing when DEM are employed for radiometric correction.
MorÈ, G.; Pesquer, L.; Blanes, I.; Serra-Sagristý, J.; Pons, X.
Analysis of lignin from archaeological waterlogged wood by direct exposure mass spectrometry (DEMS) and PCA evaluation of mass spectral data
The chemical characterisation of waterlogged archaeological wood is of fundamental importance to understand the degradation processes undergone by wooden objects and consequently to develop suitable consolidation and conservation procedures. Lignin extracted from archaeological waterlogged wood samples was characterized using direct exposure electron ionisation mass spectrometry (DE-MS). DE-MS achieves a mass spectral fingerprint of the sample in a few minutes, avoiding
F. Modugno; E. Ribechini; M. Calderisi; G. Giachi; M. P. Colombini
Time series analysis of SAR interferometry derived DEM of Kuwait desert to reduce the affects of atmosphere
NASA Astrophysics Data System (ADS)
Twenty five ASAR scenes are analyzed to find the suitable pairs for generating DEM of Kuwait desert area. About 40 pairs are suitable for generating DEMs. A unique combination of seven DEM are possible with a single master image whose perpendicular baseline component varies between 233 to 393m. GAMMA inerferometric package coupled with ERDAS image processing package are used in the analysis. The seven DEMs are compared with the 90 m DEM derived from SRTM. It has been found that the RMS error varies from 1.9 m to 15.3 m. The highest RMS error refers to day-difference of 525 days with average coherence value of 0.71 (lowest of all). Therefore, correlation will be the cause of higher errors. However, 35 days day-difference pair gave RMS error of 5.5 m with highest coherence value (0.93) which is supposed to produce the lowest RMS error. For the study of spatial distribution of errors, Interferometric DEMs are subtracted from DEM of SRTM. From this analysis, it is observed that the atmospheric affects are aligned and varies systematically. It can give an error in elevation as high as 15 m. Therefore, one should be very careful in using SAR interfoermetry technology for DEM generation even for desert regions.
Rao, K. S.; Al Jassar, H. K.
Review of Discrete Element Method (DEM) Particle Shapes and Size Distributions for Lunar Soil.
National Technical Information Service (NTIS)
As part of ongoing efforts to develop models of lunar soil mechanics, this report reviews two topics that are important to discrete element method (DEM) modeling the behavior of soils (such as lunar soils): (1) methods of modeling particle shapes and (2) ...
J. E. Lane P. T. Metzger R. A. Wilkinson
Volcanic geomorphology and tectonics of the Aeolian archipelago (Southern Italy) based on integrated DEM data
The geomorphological and morphometric analysis of the sea floor topography surrounding the Aeolian Islands, South Tyrrhenian Sea, Italy, provides insights into the relationships between the volcanological evolution of the islands and their tectonic features. We constructed geomorphological maps of the submarine portions of the seven large edifices constituting the islands on the basis of a DEM with a 5Ým resolution
Massimiliano Favallim; D·vid Kar·tson; Roberto Mazzuoli; Maria Teresa Pareschi; Guido Ventura
Dem Extraction from CHANG'E-1 Lam Data by Surface Skinning Technology
NASA Astrophysics Data System (ADS)
DEM is a digital model or 3-D representation of a terrain's surface and it is created from terrain elevation data. The main models for DEM extraction based on Lidar data or Laser Altimeter data currently use the idea that point cloud is scattered, such as regular grid model, TIN model and contour model. Essentially, in these above methods, the discrete points are interpolated into regular grid data and irregular grid data. In fact, point cloud generated by Laser Altimeter is not totally scattered, but have some regularity. In this paper, to utilize this regularity, the proposed method adopts surface skinning technology to generate DEM from Chang'E-1 Laser Altimeter data. The surface skinning technology is widely used in the field of mechanical engineering. Surface skinning is the process of passing a smooth surface through a set of curves called sectional curves, which, in general, may not be compatible. In the process of generating section line, a need for attention is that it needs to use curvature method to get a set of characteristic points, and these feature points were used to subdivide segment; the next step is generating several curves on some key places. These curves describe the shape of the curved surface. The last step is to generate a curved surface that through these curves. The result shows that, this idea is feasible, useful and it provides a novel way to generate accurate DEM.
Zhang, X.-B.; Zhang, W.-M.
Mapping within-field soil drainage using remote sensing, DEM and apparent soil electrical conductivity
In this study, we evaluated the capability of different datasets for soil drainage mapping within agricultural fields. The evaluated datasets include apparent soil electrical conductivity (ECa), remotely sensed high-resolution airborne hyperspectral reflectance (HR) and C-band synthetic aperture radar (SAR) backscattering coefficients, and a high precision digital elevation model (DEM) generated from GPS measurements. The study site was located in an
Jiangui Liu; Elizabeth Pattey; Michel C. Nolin; John R. Miller; Oumar Ka
Synthetic aperture radar for DEM generation in snow-covered mountain terrain
Digital elevation model (DEM) generation has mainly been based on optical imagery and photogrammetric techniques. However, in recent years there has been a growing interest in the use of synthetic aperture radar (SAR) for this purpose. It is mainly two techniques that are used, SAR interferometry and stereoSAR. We have studied the influence of the snow cover on the accuracy
Kjell Arild Hogda; Tore Guneriussen; Inge Lauknes
A problem-oriented approach for DEM data management and manipulation
NASA Astrophysics Data System (ADS)
For the last decades, GIS software technologies have made tremendous development and applied to many special fields when their targets are relevant to geographical locations. But the basis of cartographic mapping of GIS is a restriction for more development in GIS data modelling, storage and manipulation. Recently, much attention is being paid on ORDBMS(Object Relational Database Management System) to represent and manage GIS Data. New approaches have earned acceptance in many research communities and several proposals have emerged in commercial software for solving the management and manipulation on GIS vector data. Though the storage and management of field-based model data(e.g. raster, DEM, TIN) have got less achievement and people still use files and procedural ways to manipulation field-based GIS data in common applications. In this paper a new structure model using ORDBMS technology for field-based data's storage and management was proposed on the basis of full discussion on several GIS data management technologies, then a problem-oriented approach for DEM data management and manipulation was designed and implemented through open source software systems PostgreSQL and Python language. Experimental examples of different DEM data souces were stored, managed and used by using the extended spatial database system. The experiments illustrated that this solution would be a useful supplement to spatial database and it provided an effective way to DEM data management and analysis, and support the interoperability between vector data and field data.
Huang, Fengru; Fang, Yu; Chen, Bin
Application of multi-temporal DEM data in calculating the Earth's surface deformation
NASA Astrophysics Data System (ADS)
This paper suggests a method of calculating the elevation and the volume change of the terrain based on the multitemporal digital elevation model (DEM) data sets for the same area. Two methods for calculating the surface change are introduced: One is based on the regular square grids (RSG), another uses the triangulated irregular network (TIN) generalized from the original source data by the 3D Douglas-Peucker algorithm so that not only the accuracy of generalization using 3D Douglas-Peucker is verified, but also the kinds of data formats of DEM for this purpose have been expanded. Finally, the formulae used by these two methods are introduced, and the experimental results calculated from the same original DEM data acquired in 1971 and 2000 respectively form the area of Bayanbulak in Xinjiang are compared. The experiments have shown that the results of the two methods are relatively identical even if under the great generalization degree of DEM for the second method. Therefore, it shows that the second method can greatly heighten the efficiency of the calculation while insuring its accuracy.
Lan, Qiuping; Fei, Lifan; Liu, Yining; Zhang, Kun
The Relative Importance of Inserting TIN Topographic Breaklines in DEM Creation
NASA Astrophysics Data System (ADS)
The application of digital elevation models (DEM's) for geomorphic change detection and assessment of instream freshwater anadromous fish habitat has grown considerably in the last decade. Recent advances in remote sensing technologies such as LiDAR, as well as ground-based, high-resolution topographic survey equipment allow for rapid collection of high accuracy point data at a finer spatial scale than was previously available. Additionally, modern computational efficiency allows for an increased number of users to manipulate the large data sets produced from the aforementioned technologies. The post processing tools and methodologies necessary to meaningfully apply these data are increasingly recognized as vital. This work quantifies the elevational effects on DEM's of topographic breakline insertion during the editing of triangulated irregular networks (TIN's). Geomorphic change detection software including the use of a fuzzy inference system was used to compare the elevational differences between DEM's with and without the addition of breaklines. Results vary outside the active channel but from within the active channel there was a relatively small net elevational loss to both total area and volume for the breakline inserted DEM's. The significance of this net loss will continue to be explored but our current findings suggest the value of topographic breaklines to reduce elevational error in terrain model accuracy
Portugal, E. W.; Bangen, S. G.; Wheaton, J. M.
This data set is a geographic information system (GIS) coverage of the 90-meter digital elevation model (DEM) for the United States Environmental Protection Agency (USEPA) Mid-Atlantic Integrated Assessment (MAIA) Project region. The coverage was produced using US Geological Su...
Estimation of solar radiation using GMS and DEM data for determination of suitable agricultural land
The objective of this study is estimation of solar radiation using GMS and DEM data. It is important to get hourly amounts of solar radiation in a large area for determination of suitable agricultural land. Especially in mountainous area, slope and solar shading affect solar radiation. The following were performed in this study; 1) recovery of missing albedo through interpolation,
Jun Osozawa; Hokuto Kano; Ryutaro Tateishi
A simplified DEM-CFD approach for pebble bed reactor simulations
In pebble bed reactors (PBR's), the pebble flow and the coolant flow are coupled with each other through coolant-pebble interactions. Approaches with different fidelities have been proposed to simulate similar phenomena. Coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) approaches are widely studied and applied in these problems due to its good balance between efficiency and accuracy. In this work, based on the symmetry of the PBR geometry, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without significant loss of accuracy. Pebble flow is simulated by a full 3-D DEM, while the coolant flow field is calculated with a 2-D CFD simulation by averaging variables along the annular direction in the cylindrical geometry. Results show that this simplification can greatly enhance the efficiency for cylindrical core, which enables further inclusion of other physics such as thermal and neutronic effect in the multi-physics simulations for PBR's. (authors)
Li, Y.; Ji, W. [Dept. of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Inst., JEC 5040 MANE, 110 8th Street, Troy, NY 12180 (United States)
Landform analysis of slope movements using DEM in Higashikubiki area, Japan
Various numerical analyses using 25m-grid DEMs were compared with rasterized slope movement distribution maps and geological maps of the Higashikubiki area in Niigata Prefecture, Japan. Slope movement distribution maps included five classes: ìstable slopeî, ìlandslide massî, ìlandslide scarpî, ìcollapse scarpî and ìcrackî. Their statistical characteristics were clarified by numerical landform analyses for each lithology. Frequency distributions of slope angle were
Junko Iwahashi; Shiaki Watanabe; Takahiko Furuya
Pore size distributions calculated from 3-D images of DEM-simulated powder compacts
Numerical methods for determining pore size distributions from 3-D digitized microstructures of plastically compacted powders are presented. The microstructures are generated by simulations using the discrete element method (DEM). Two types of pore size distribution are considered: first, a ìchamberî pore size distribution similar to the pore size distribution measured by quantitative metallography, second, a ìthroatî pore size distribution that
S. M Sweeney; C. L Martin
The integration of spectral analyses of Landsat ETM+ with the DEM data for mapping mangrove forests
This study aims to develop an efficient method to extract mangrove forests at a regional scale using remote sensing data and Geographic Information Systems (GIS) technique. A regional mangrove forests mapping method was developed based on the spectral characteristics and the topographic existence condition of mangrove forests. Landsat Enhanced Thematic Mapper plus (ETM+) and digital elevation model (DEM) were used
Bayan Alsaaideh; Ahmad Al-Hanbali; Ryutaro Tateishi; Hoan Nguyen Thanh
Hydrology, secondary growth, and elevation accuracy in two preliminary Amazon Basin SRTM DEMs
NASA Astrophysics Data System (ADS)
Two preliminary Shuttle Radar Topography Mission digital elevation models (SRTM DEMs) of Manaus (1S to 5S and 59W to 63W) and Rondonia (9S to 12S and 61W to 64W) were received from the "PI Processor" at NASA JPL. We compared the Manaus DEM (C-band) with a previously constructed Cabaliana floodplain classification based on Global RainForest Mapping (GRFM) JERS-1 SAR data (L-band) and determined that habitats of open water, bare ground, and flooded shrub contained the lowest elevations; macrophyte and non-flooded shrub habitats are marked by intermediate elevations; and the highest elevations are found within flooded and non-flooded forest. Although the water surface typically produces specular reflections, double-bounce travel paths result from dead, leafless trees found across the Balbina reservoir near Manaus. There (i.e., in Balbina) the water surface is marked by pixel-to-pixel height changes of generally 0 to 1 m and changes across a ò100 km transect rarely exceed 3 m. Reported SRTM errors throughout the transect range from 1 to 2 m with some errors up to 5 m. The smooth Balbina surface contrasts with the wind-roughened Amazon River surface where SRTM height variations easily range from 1 to 10 m (reported errors often exceed 5 m). Deforestation and subsequent regrowth in the Rondonia DEM is remarkably clear. Our colleagues used a 20 year sequence of Landsat TM/MSS classified imagery to delineate areas in various stages of secondary growth and we find a general trend of increasing vegetation height with increasing age. Flow path networks derived from the Cabaliana floodplain DEM are in general agreement with networks previously extracted from the GRFM mosaics; however, watershed boundaries differ. We have also developed an algorithm for extracting channel widths, which is presently being applied to the DEM and classified imagery to determine morphological variations between reaches.
Alsdorf, D.; Hess, L.; Sheng, Y.; Souza, C.; Pavelsky, T.; Melack, J.; Dunne, T.; Hendricks, G.; Ballantine, A.; Holmes, K.
Inter-agency comparison of TanDEM-X baseline solutions
NASA Astrophysics Data System (ADS)
TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) is the first Synthetic Aperture Radar (SAR) mission using close formation flying for bistatic SAR interferometry. The primary goal of the mission is to generate a global digital elevation model (DEM) with 2 m height precision and 10 m ground resolution from the configurable SAR interferometer with space baselines of a few hundred meters. As a key mission requirement for the interferometric SAR processing, the relative position, or baseline vector, of the two satellites must be determined with an accuracy of 1 mm (1D RMS) from GPS measurements collected by the onboard receivers. The operational baseline products for the TanDEM-X mission are routinely generated by the German Research Center for Geosciences (GFZ) and the German Space Operations Center (DLR/GSOC) using different software packages (EPOS/BSW, GHOST) and analysis strategies. For a further independent performance assessment, TanDEM-X baseline solutions are generated at the Astronomical Institute of the University of Bern (AIUB) on a best effort basis using the Bernese Software (BSW). Dual-frequency baseline solutions are compared for a 1-month test period in January 2011. Differences of reduced-dynamic baseline solutions exhibit a representative standard deviation (STD) of 1 mm outside maneuver periods, while biases are below 1 mm in all directions. The achieved baseline determination performance is close to the mission specification, but independent SAR calibration data takes acquired over areas with a well known DEM from previous missions will be required to fully meet the 1 mm 1D RMS target. Besides the operational solutions, single-frequency baseline solutions are tested. They benefit from a more robust ambiguity fixing and show a slightly better agreement of below 1 mm STD, but are potentially affected by errors caused by an incomplete compensation of differential ionospheric path delays.
J‰ggi, A.; Montenbruck, O.; Moon, Y.; Wermuth, M.; Kˆnig, R.; Michalak, G.; Bock, H.; Bodenmann, D.
Detailed geomorphological mapping from high resolution DEM data (LiDAR, TanDEM-X): two case studies from Germany and SE Tibet
NASA Astrophysics Data System (ADS)
Two major obstacles are hampering the production of high resolution geomorphological maps: the complexity of the subject that should be depicted and the enormous efforts necessary to obtain data by field work. The first factor prevented the establishment of a generally accepted map legend; the second hampered efforts to collect comprehensive sets of geomorphological data. This left geomorphologists to produce applied maps, focusing on very few layers of information and often not sticking to any of the numerous standards proposed in the second half of the 20th century. Technological progress of the recent years, especially in the fields of digital elevation models, GIS environments, and computational hardware, today offers promising opportunities to overcome the obstacles and to produce detailed geomorphological maps even for remote or inhospitable regions. The feasibility of detailed geomorphological mapping from two new sets of digital elevation data, the 1 m LiDAR DTM provided by Germany's State Surveying Authority and the upcoming TanDEM-X DEM, has been evaluated in two case studies from a low mountain range in Germany and a high mountain range in SE Tibet. The results indicate that most layers of information of classical geomorphological maps (e.g. the German GMK) can be extracted from this data at appropriate scales but that significant differences occur concerning the quality and the grades of certainty of key contents. Generally, an enhancement of the geomorphographical, especially the geomorphometrical, and a weakening of geomorphogenetical contents was observed. From these findings, theoretical, methodological, and cartographical remarks on detailed geomorphological mapping from DEM data in GIS environments were educed. As GIS environments decouple data and design and enable the geomorphologist to choose information layer combinations freely to fit research topics, a general purpose legend becomes obsolete. Yet, a unified data structure is demanded to ensure that data collected by different scientists or in different studies can be exchanged and reused.
Loibl, D.
Fusion of high-resolution DEMs derived from COSMO-SkyMed and TerraSAR-X InSAR datasets
NASA Astrophysics Data System (ADS)
Voids caused by shadow, layover, and decorrelation usually occur in digital elevation models (DEMs) of mountainous areas that are derived from interferometric synthetic aperture radar (InSAR) datasets. The presence of voids degrades the quality and usability of the DEMs. Thus, void removal is considered as an integral part of the DEM production using InSAR data. The fusion of multiple DEMs has been widely recognized as a promising way for the void removal. Because the vertical accuracy of multiple DEMs can be different, the selection of optimum weights becomes a key problem in the fusion and is studied in this article. As a showcase, two high-resolution InSAR DEMs near Mt. Qilian in northwest China are created and then merged. The two pairs of InSAR data were acquired by TerraSAR-X from an ascending orbit and COSMO-SkyMed from a descending orbit. A maximum likelihood fusion scheme with the weights optimally determined by the height of ambiguity and the variance of phase noise is adopted to syncretize the two DEMs in our study. The fused DEM has a fine spatial resolution of 10 m and depicts the landform of the study area well. The percentage of void cells in the fused DEM is only 0.13 %, while 6.9 and 5.7 % of the cells in the COSMO-SkyMed DEM and the TerraSAR-X DEM are originally voids. Using the ICESat/GLAS elevation data and the Chinese national DEM of scale 1:50,000 as references, we evaluate vertical accuracy levels of the fused DEM as well as the original InSAR DEMs. The results show that substantial improvements could be achieved by DEM fusion after atmospheric phase screen removal. The quality of fused DEM can even meet the high-resolution terrain information (HRTI) standard.
Jiang, Houjun; Zhang, Lu; Wang, Yong; Liao, Mingsheng
Quantifying geological structures of the Nigde province in central Anatolia, Turkey using SRTM DEM data
NASA Astrophysics Data System (ADS)
A digital terrain model and a 3D fly-through model of the Nigde province in central Anatolia, Turkey were generated and quantitatively analyzed employing the shuttle radar topographic mission (SRTM) digital elevation model (DEM). Besides, stream drainage patterns, lineaments and structural-geological features were extracted and analyzed. In the process of analyzing and interpreting the DEM for landforms, criteria such as color and color tones (attributes of heights), topography (shaded DEM and 3D fly-through model) and stream drainage patterns were employed to acquire geo-information about the land, such as hydrologic, geomorphologic, topographic and tectonic structures. In this study, the SRTM DEM data of the study region were experimentally used for both DEM classification and quantitative analysis of the digital terrain model. The results of the DEM classification are: (1) low plain including the plains of Bor and Altunhisar (20.7%); (2) high plain including the Misli (Konakli) plain (28.8%); (3) plateau plain including the Melendiz (Ciftlik) plateau plain (1.0%); (4) mountain including the Nigde massif (33.3%); and (5) high mountain (16.2%). High mountain areas include a caldera complex of Mt Melendiz, Mt Hasan and Mt Pozanti apart from the Ala mountains called Aladaglar and the Bolkar mountains called Bolkarlar in the study region (7,312 km2). Analysis of both the stream drainage patterns and the lineaments revealed that the Nigde province has a valley zone called Karasu valley zone (KVZ) or Nigde valley zone (NVZ), where settlements and agricultural plains, particularly the Bor plain in addition to settlements of the Bor town and the central city of Nigde have the most flooding risk when a heavy raining occurs. The study revealed that the NVZ diagonally divides the study region roughly into two equal parts, heading from northeast to southwest. According to the map created in this study, the right side of the NVZ has more mountainous area, where the Aladaglar is a wildlife national park consisting of many species of fauna and flora whereas the left side of the NVZ has more agricultural plain, with exception of a caldera complex of Mt Melendiz and volcanic Mt Hasan. The south of the study region includes the Bolkarlar. In addition, the Ecemis fault zone (EFZ) lying along the Ecemis rivulet, running from north to south at the west side of the Aladaglar, forms the most important and sensitive location in the region in terms of the tectonics.
Demirkesen, A. C.
Comparison of a Range of Terrain Variables Derived From DEMs Based on Different Resolutions and Input Data
NASA Astrophysics Data System (ADS)
It is a well-known fact that the grid cell size of a raster digital elevation model has significant effects on derived terrain variables such as slope, aspect, plan and profile curvature or the wetness index. This poster presents vital information for users of DEMs generated from 100 m regularly sampled, or similar, elevation points such as those available province-wide for Alberta, Canada. Findings are valid for flat to moderately sloped terrain present in the North American prairies and foothills regions and other locations with similar terrain. DEMs with grid cell sizes ranging from 100 to 5 m were interpolated from both 100 and 10 m regularly spaced elevation points using the ANUDEM interpolation method. Significant differences in a number of terrain variables derived from DEMs with different resolutions using cumulative distribution functions and a subsequent Kolmogorov-Smirnov test are revealed. Terrain variables based on 100 m regularly sampled elevation points (100 m DEM) are compared to a DEM based on 10 m regularly sampled elevation points which serves as a benchmark. Correlation analysis reveals that only elevation and slope have a strong positive relationship while all other terrain derivatives are not represented realistically. Relative root mean square errors quantify the quality of terrain derivatives. Major findings are summarised as follows: (a) All computed terrain variables tested (slope, aspect, plan and profile curvature, curvature and the wetness index) vary significantly with a change in grid cell size; (b) the higher the order of the derivative, the smaller the DEM resolution should be; (c) only elevation and slope show a high correlation between the 100 m DEM and the benchmark DEM; (d) the 100 m DEM can, therefore, only be used to show the general range and general spatial distribution of terrain variables, but fails - with the exception of slope - to represent spatially correctly the terrain variables at the associated scale.
Kienzle, S. W.
DEM evaluation by an operator and facets stereo vision: a comparison based on close-range imagery
NASA Astrophysics Data System (ADS)
In this paper we compare the results of DEM estimation by a photogrammetric operator with the analytic plotter LEICA AC3 and an automatic object space based reconstruction method (Facets Stereo Vision). We are working with close-range images of natural stone surfaces, taken in cooperation with curators of monuments to monitor the weathering of stones. Two windows representative of the surface were selected and DEMs evaluated by an operator and Facets Stereo Vision. For the computation with Facets Stereo Vision a horizontal plane was introduced as initial value. Image pyramid techniques were applied for the final DEM estimation. Differences, problems of the comparison, and the results are discussed.
Kempa, M.; Schlueter, Martin
DEM generation method from contour lines based on the steepest slope segment chain and a monotone interpolation function
NASA Astrophysics Data System (ADS)
In this paper, a method to generate a digital elevation model (DEM) from contour lines is proposed. The method is characterized by 16 search directions to find the steepest slope direction from a grid point to the nearest and second nearest contour lines, an interpolation along the steepest slope segment chain, an improved identification of slope grid points, and a monotone interpolation provided by a simple cubic Hermit function to interpolate slope grid points. Noticeable improvements are achieved in the generated DEM from the proposed method against the DEM produced by the Geological Survey Institute (GSI) of Japan.
Oky Dicky Ardiansyah, Prima; Yokoyama, Ryuzo
A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment
NASA Astrophysics Data System (ADS)
A high resolution surface topography Digital Elevation Model (DEM) is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets this specification. We present a new 100-m DEM of the Antarctic Peninsula (63-70∞ S), based on ASTER Global Digital Elevation Model (GDEM) data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA) imagery. The new DEM has a mean elevation difference of +3 m (±26 m RMSE) from ICESat, and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: dems/datasets.html="_blank">http://nsidc.org/data/dems/datasets.html (http://dx.doi.org/10.5060/D47P8W9D).
Cook, A. J.; Murray, T.; Luckman, A.; Vaughan, D. G.; Barrand, N. E.
DEM simulation of particles of complex shapes using the multisphere method: Application for additive manufacturing
NASA Astrophysics Data System (ADS)
Additive manufacturing constitutes a promising production technology with potential application in a broad range of industrial areas. In this type of manufacturing process, objects are created from powder particles by adding layers of material upon one another through selectively melting particles from the powder bed. However, understanding the mechanical behavior of the powder during manufacturing as a function of material properties and particle shape is an essential pre-requisite for optimizing the production process. Here we develop a numerical tool for modeling the dynamics of powder particles during additive manufacturing based on force-based simulations by means of the Discrete Element Method (DEM). An existing DEM software (LIGGGHTS) is extended in order to study the transport of powder particles of complex geometric shapes through accounting for the boundary conditions inherent to the manufacturing process.
Parteli, Eric J. R.
Flexible image registration for the identification of best fitted protein models in 3DEM maps
In this work we propose an image registration algorithm to automatically fit protein atomic domain models into medium-resolution three-dimensional electron microscopy reconstructions (3D-EM map). The approach employs a flexible registration algorithm whose optimizer controls the generation of stereo-chemically correct models from a given reference domain belonging to a super-family of proteins. The proposed algorithm generates models automatically in the correct
Laura Fernandez-de-manuel; MarÌa J. Ledesma-carbayo; Julian Atienza-herrero; Carlos Oscar S·nchez Sorzano; JosÈ-MarÌa Carazo; AndrÈs Santos
A comparative analysis of DEM?based models to estimate the solar radiation in mountainous terrain
Daily solar radiation estimates of four up?to?date solar radiation models (Solar Analyst, r.sun, SRAD and Solei?32), based on a digital elevation model (DEM), have been evaluated and compared in a Mediterranean environment characterized by a complex topography. The models' estimates were evaluated against 40 days of radiometric data collected in 14 stations. Analyzed sky conditions ranged from completely overcast conditions
H. Alsamamra
A 'Drift' algorithm for integrating vector polyline and DEM based on the spherical DQG
NASA Astrophysics Data System (ADS)
The efficient integration method of vector and DEM data on a global scale is one of the important issues in the community of Digital Earth. Among the existing methods, geometry-based approach maintains the characteristics of vector data necessary for inquiry and analysis. However, the complexity of geometry-based approach, which needs lots of interpolation calculation, limits its applications greatly in the multi-source spatial data integration on a global scale. To overcome this serious deficiency, a novel 'drift' algorithm is developed based on the spherical Degenerate Quadtree Grid (DQG) on which the global DEMs data is represented. The main principle of this algorithm is that the vector node in a DQG cell can be moved to the cell corner-point without changing the visualization effects if the cell is smaller or equal to a pixel of screen. A detailed algorithm and the multi-scale operation steps are also presented. By the 'drift' algorithm, the vector polylines and DEM grids are integrated seamlessly, avoiding lots of interpolation calculating. Based on the approach described above, we have developed a computer program in platform OpenGL 3D API with VC++ language. In this experiment, USGS GTOPO30 DEM data and 1:1,000,000 DCW roads data sets in China area are selected. Tests have shown that time consumption of the 'drift' algorithm is only about 25% of that of the traditional ones, moreover, the mean error of drift operation on vector nodes can be controlled within about half a DQG cell. In the end, the conclusions and future works are also given.
Wang, Jiaojiao; Wang, Lei; Cao, Wenmin; Zhao, Xuesheng
Diagnostic of the temperature and differential emission measure (DEM) based on Hinode\\/XRT data
We discuss here various methodologies and an optimal strategy of the\\u000atemperature and emission measure diagnostics based on Hinode X-Ray Telescope\\u000adata. As an example of our results we present determination of the temperature\\u000adistribution of the X-rays emitting plasma using filters ratio method and three\\u000avarious methods of the calculation of the differential emission measure (DEM).\\u000aWe have found
M. Siarkowski; R. Falewicz; A. Kepa; P. Rudawy
Energy Crisis in the Superbubble DEM L 192 (N 51D)
Superbubbles surrounding OB associations provide ideal laboratories to study\\u000athe stellar energy feedback problem because the stellar energy input can be\\u000aestimated from the observed stellar content of the OB associations and the\\u000ainterstellar thermal and kinetic energies of superbubbles are well-defined and\\u000aeasy to observe. We have used DEM L 192, also known as N 51D, to carry out
Randall L. Cooper; Mart ¥ ın; A. Guerrero; You-Hua Chu; H. Rosie Chen
Analysis of wave propagation in dry granular soils using DEM simulations
In this paper, a three-dimensional particle-based technique utilizing the discrete element method (DEM) is proposed to study\\u000a wave propagation in a dry granular soil column. Computational simulations were conducted to investigate the soil response\\u000a to sinusoidal motions with different amplitudes and frequencies. Three types of soil deposits with different void ratios were\\u000a employed in these simulations. Different boundary conditions at
Natasha Zamani; Usama El Shamy
An Integrated Approach to Accurate dem Generartion Using Airboren Full Waveform LIDAR Data
NASA Astrophysics Data System (ADS)
In this study, full waveform LiDAR data were exploited to improve the generation of a large-scale digital elevation model (DEM). Building on the methods of progressive generation of triangulation irregular network (TIN) model reported in the literature, we proposed an integrated approach. In this method, echo detection, terrain identification, and TIN generation were performed synergically and iteratively, instead of their separate determinations as in most DEM generation methods. This method started with a TIN model made up of terrain points detected using a morphological opening operation and a curve matching method. For any given TIN facet, the full waveforms of the return associated with the laser pulses interacting with this TIN facet were examined near the surface for any terrain echoes. The TIN was then updated using the newly detected terrain points. These processes were iterated until no new terrain points were identified. The developed method was tested on a data set collected by a Riegl LMS Q-560 scanner over a study area near Sault Ste. Marie, Ontario, Canada (46∞33'56''N, 83∞25'18''W). The results demonstrated that 30% more terrain points were identified under shrubs and trees using this integrated approach, compared with the commonly used Gaussian decomposition method. The DEMs generated by the developed method exhibited more details in the terrain for two test sites than those obtained by using the TerraScan software.
Hu, B.; Gumerov, D.; Wang, J.-G.
Energy Crisis in the Superbubble DEM L192 (N51D)
NASA Astrophysics Data System (ADS)
Superbubbles surrounding OB associations provide ideal laboratories in which to study the stellar energy feedback problem, because the stellar energy input can be estimated from the observed stellar content of the OB associations, and the interstellar thermal and kinetic energies of superbubbles are well defined and easy to observe. We have used DEM L192, also known as N51D, to carry out a detailed case study of the energy budget in a superbubble, and we find that the expected amount of stellar mechanical energy injected into the interstellar medium, (18+/-5)◊1051 ergs, exceeds the amount of thermal and kinetic energies stored in the superbubble, (6+/-2)◊1051 ergs. Clearly, a significant fraction of the stellar mechanical energy must have been converted into other forms of energy. The X-ray spectrum of the diffuse emission from DEM L192 requires a power-law component to explain the featureless emission at 1.0-3.0 keV. The origin of this power-law component is unclear, but it may be responsible for the discrepancy between the stellar energy input and the observed interstellar energy in DEM L192.
Cooper, Randall L.; Guerrero, MartÌn A.; Chu, You-Hua; Chen, C.-H. Rosie; Dunne, Bryan C.
Detection and evaluation on phosphorite mining environment contamination sources using ASTER and DEM
NASA Astrophysics Data System (ADS)
The main environment contamination source of the phosphorite mining area, located in Huji city, Hubei province, China, was detected and evaluated using ASTER and DEM. Firstly, the featured spectrum that has unique diagnose spectral feature was generalized after analyzing the types and spectrum characteristics of the sample contamination source in the area. Secondly, the main contamination source of the area was recognized by means of principal component analysis using ASTER band 1-9. And the distributions of them were in accordance with that of phosphorite, carbonate and waste water. Finally, flow accumulation and catchment images were simulated using DEM and GIS. By analyzing the images of the flow accumulation, catchment and contamination source, the authors conclude that large scale opencast phosphorite mining and solid waste materials have damaged mining environment; the disordered piling of solid waste material has been boosting diffusion and migration of harmful and toxic matters; and all of these has damaged heavily ecological environment of lower reaches, and is the potential unsafe factor for that of Hanjiang river also. Keywords: ASTER, DEM, mining contamination, detection and evaluation on contamination sources 1.
Chen, Wei-tao; Zhang, Zhi; Li, Zhi-zhong; Yang, Jun-jie; Qian, Li-ping
A new method of surface modeling and its application to DEM construction
NASA Astrophysics Data System (ADS)
A new method of surface modelling based on the fundamental theorem of surfaces (SMTS) is presented. Eight different test surfaces are employed to comparatively analyze the simulation errors of SMTS and the classical methods of surface modeling in GIS, including TLI (triangulated irregular network with linear interpolation), SPLINE, IDW (inverse distance weighted) and KRIGING. Numerical tests show that SMTS is much more accurate than the classical methods. SMTS theoretically gives a solution to the error problem that has long troubled DEM construction. As a real-world example, SMTS is used to construct a DEM of the Da-Fo-Si coal mine in Shaan-Xi Province, China. Its root mean square error (RMSE) is compared with those of DEMs constructed by the four classical methods. The results show that although SMTS also has a higher accuracy in the real-world example, the improvement of accuracy is less distinct than that expected from the numerical tests. The accuracy loss seems to be caused by location differences between sampling points and the central points of lattices of the simulated surfaces. Two alternative ways are proposed to solve this problem.
Yue, Tian-Xiang; Du, Zhen-Ping; Song, Dun-Jiang; Gong, Yun
A Review of Discrete Element Method (DEM) Particle Shapes and Size Distributions for Lunar Soil
NASA Technical Reports Server (NTRS)
As part of ongoing efforts to develop models of lunar soil mechanics, this report reviews two topics that are important to discrete element method (DEM) modeling the behavior of soils (such as lunar soils): (1) methods of modeling particle shapes and (2) analytical representations of particle size distribution. The choice of particle shape complexity is driven primarily by opposing tradeoffs with total number of particles, computer memory, and total simulation computer processing time. The choice is also dependent on available DEM software capabilities. For example, PFC2D/PFC3D and EDEM support clustering of spheres; MIMES incorporates superquadric particle shapes; and BLOKS3D provides polyhedra shapes. Most commercial and custom DEM software supports some type of complex particle shape beyond the standard sphere. Convex polyhedra, clusters of spheres and single parametric particle shapes such as the ellipsoid, polyellipsoid, and superquadric, are all motivated by the desire to introduce asymmetry into the particle shape, as well as edges and corners, in order to better simulate actual granular particle shapes and behavior. An empirical particle size distribution (PSD) formula is shown to fit desert sand data from Bagnold. Particle size data of JSC-1a obtained from a fine particle analyzer at the NASA Kennedy Space Center is also fitted to a similar empirical PSD function.
Lane, John E.; Metzger, Philip T.; Wilkinson, R. Allen
Effects of Scale on DEM Derived Drainage Networks For a High Arctic Wetland Complex
NASA Astrophysics Data System (ADS)
The ability to automatically generate drainage patterns is a useful tool in hydrologic studies, especially in remote areas where limited data is available. However drainage patterns derived from digital elevation data can be significantly affected by the scale of the data from which they are generated. This study investigates the effects of scaling on drainage patterns extracted from elevation data for a low gradient wetland area on Somerset Island, Nunavut, in the Canadian High Arctic. A series of Digital Elevation Models (DEM's) were created from digitized topographic information at varying resolutions (2.5 m, 5 m. 10 m, 50 m, 100 m, 200 m). Automated drainage network extractions were performed for each resolution grid, using ESRI ArcInfo software. A series of flow networks were created for each resolution DEM using varying minimum stream lengths in order to examine the effects of this variable on flow pattern and direction. The modelled drainage at each resolution was then compared to the `actual' drainage mapped from aerial photography (air photos and low level oblique photographs) and topographic maps to examine differences as a result of scaling. Preliminary results suggest that reproducing correct flow direction was not possible with the coarser resolution DEMs (10 m and up), while the finer resolutions (2.5 m, 5 m) resulted in drainage networks most similar to the mapped drainage.
Brown, L. C.; Young, K. L.
Research on terrain analysis of mass DEM data based on grid computing
NASA Astrophysics Data System (ADS)
With the development of spatial data acquisition technology, the surveying departments have acquired mass DEM Data at terabyte-scale. The current GIS software and computing methods can not meet the demand of analyzing and mining these mass data. A new kind of computing infrastructure is expected to support distributed access to and analysis of these datasets by potentially thousands of users. Grid computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and , in some cases, high-performance orientation. This paper focuses on the key problems of terrain analysis of mass DEM data based on grid computing and makes the following contributions. First, we review the current terrain analysis algorithms based on DEM data and analysis the parallel algorithms. Next, we proposed a DTA (Digital Terrain Analysis) grid and analyze the architecture and key problems of the DTA grid. Finally, the experiment system developed based on grid middleware is introduced.
Xie, Jibo; Gong, Jianya
Homogeneous and bubbling fluidization regimes in DEMñCFD simulations: Hydrodynamic stability of gas and liquid fluidized beds
In recent years coupled DEMñCFD models have been successfully utilized to simulate fluidized particle systems in the bubbling regime. In this paper we report on DEMñCFD simulations of liquid-fluidization of glass beads and gas-fluidization of Geldart's Group A particles carried out to characterize hydrodynamically the stability of the fluidized state, in the absence of cohesive forces. Due to the importance
Alberto Di Renzo; Francesco Paolo Di Maio
Creating High Quality DEMs of Large Scale Fluvial Environments Using Structure-from-Motion
NASA Astrophysics Data System (ADS)
During the past decade, advances in survey and sensor technology have generated new opportunities to investigate the structure and dynamics of fluvial systems. Key geomatic technologies include the Global Positioning System (GPS), digital photogrammetry, LiDAR, and terrestrial laser scanning (TLS). The application of such has resulted in a profound increase in the dimensionality of topographic surveys - from cross-sections to distributed 3d point clouds and digital elevation models (DEMs). Each of these technologies have been used successfully to derive high quality DEMs of fluvial environments; however, they often require specialized and expensive equipment, such as a TLS or large format camera, bespoke platforms such as survey aircraft, and consequently make data acquisition prohibitively expensive or highly labour intensive, thus restricting the extent and frequency of surveys. Recently, advances in computer vision and image analysis have led to development of a novel photogrammetric approach that is fully automated and suitable for use with simple compact (non-metric) cameras. In this paper, we evaluate a new photogrammetric method, Structure-from-Motion (SfM), and demonstrate how this can be used to generate DEMs of comparable quality to airborne LiDAR, using consumer grade cameras at low costs. Using the SfM software PhotoScan (version 0.8.5), high quality DEMs were produced for a 1.6 km reach and a 3.3 km reach of the braided Ahuriri River, New Zealand. Photographs used for DEM creation were acquired from a helicopter flying at 600 m and 800 m above ground level using a consumer grade 10.1mega-pixel, non-metric digital camera, resulting in object space resolution imagery of 0.12 m and 0.16 m respectively. Point clouds for the two study reaches were generated using 147 and 224 photographs respectively, and were extracted automatically in an arbitrary coordinate system; RTK-GPS located ground control points (GCPs) were used to define a 3d non-linear transformation to convert the point clouds to the absolute NZTM coordinate system, with average errors of 0.06 m in the horizontal and 0.11 m in the vertical dimensions. The final point clouds extracted had typical point spacings of 0.25 m, well above the metric resolution of airborne LiDAR. To improve data handling, the final point cloud was decimated to point spacings of 0.5 m using a recently developed gridding procedure (Rychkov, Brasington, & Vericat, 2012), and finally converted into a DEM using a Delaunay constrained TIN in ArcGIS. Results reveal SfM's ability to produce high quality terrain products of large scale fluvial environments that can outperform LiDAR, and can potentially compare with TLS. PhotoScan offers a straightforward method to generate, transform, and export DEMs that requires little user knowledge of photogrammetric processes. Further, the affordability and reduced field work offer low budget researchers the ability to produce repeat surveys for in-depth temporal studies. Funding supported by the New Zealand Department of Conservation.
Javernick, L. A.; Brasington, J.; Caruso, B. S.; Hicks, M.; Davies, T. R.
On the COSMO-SkyMed Exploitation for Interferometric DEM Generation
NASA Astrophysics Data System (ADS)
DEM products for Earth observation space-borne applications are being to play a role of increasing importance due to the new generation of high resolution sensors (both optical and SAR). These new sensors demand elevation data for processing and, on the other hand, they provide new possibilities for DEM generation. Till now, for what concerns interferometric DEM, the Shuttle Radar Topography Mission (SRTM) has been the reference product for scientific applications all over the world. SRTM mission [1] had the challenging goal to meet the requirements for a homogeneous and reliable DEM fulfilling the DTED-2 specifications. However, new generation of high resolution sensors (including SAR) pose new requirements for elevation data in terms of vertical precision and spatial resolution. DEM are usually used as ancillary input in different processing steps as for instance geocoding and Differential SAR Interferometry. In this context, the recent SAR missions of DLR (TerraSAR-X and TanDEM-X) and ASI (COSMO-SkyMed) can play a promising role thanks to their high resolution both in space and time. In particular, the present work investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. The recent scientific works, [2] and [3], have shown the advantages of using CSK in the monitoring of terrain deformations caused by landslides, earthquakes, etc. On the other hand, thanks to the high spatial resolution, CSK appears to be very promising in monitoring man-made structures, such as buildings, bridges, railways and highways, thus enabling new potential applications (urban applications, precise DEM, etc.). We present results obtained by processing both SPOTLIGHT and STRIPMAP acquisitions through standard SAR Interferometry as well as multi-pass interferometry [4] with the aim of measuring ground elevation. Acknowledgments Work supported by ASI (Agenzia Spaziale Italiana) in the framework of the project "AO-COSMO Project ID-1462 - Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation - ASI Contract I/063/09/0". References [1] B. Rabus, M. Eineder, A. Roth, and R. Bamler, "The Shuttle Radar Topography Mission-A new class of digital elevation models acquired by spaceborne radar," ISPRS J. Photogramm. Remote Sens., vol. 57, no. 4, pp. 241-262, Feb. 2003. [2] F. BOVENGA, D. O. NITTI, R. NUTRICATO, M. T. CHIARADIA, "C- and X-band multi-pass InSAR analysis over Alpine and Apennine regions". In Proceedings of the European Space Agency Living Planet Symposium, June 28 - July 2, 2010, Bergen, Norway. [3] D. REALE, D. O. NITTI, D. PEDUTO, R. NUTRICATO, F. BOVENGA, G. FORNARO, "Postseismic Deformation Monitoring With The COSMO/SKYMED Constellation". IEEE Geoscience Remote Sensing Letters, 2011. DOI: 10.1109/LGRS.2010.2100364 [4] Nitti, D.O., Nutricato, R., Bovenga, F., Conte, D., Guerriero, L. & Milillo, G., "Quantitative Analysis of Stripmap And Spotlight SAR Interferometry with CosmoSkyMed constellation.", Proceedings if IEEE IGARSS 2009, July 13-17, 2009. Cape Town, South Africa.
Teresa, C. M.; Raffaele, N.; Oscar, N. D.; Fabio, B.
NSDL National Science Digital Library
In this case, students enter the world of a forensic anthropologist who must determine the sex and age of an individual from a collection of bones. Students, in turn, simulate some of the actual procedures conducted in a forensic anthropologist's lab, exa
Bruce, Alease
A new 100-m Digital Elevation Model of the Antarctic Peninsula derived from ASTER Global DEM: methods and accuracy assessment
NASA Astrophysics Data System (ADS)
A high resolution surface topography Digital Elevation Model (DEM) is required to underpin studies of the complex glacier system on the Antarctic Peninsula. A complete DEM with better than 200 m pixel size and high positional and vertical accuracy would enable mapping of all significant glacial basins and provide a dataset for glacier morphology analyses. No currently available DEM meets these specifications. We present a new 100-m DEM of the Antarctic Peninsula (63-70∞ S), based on ASTER Global Digital Elevation Model (GDEM) data. The raw GDEM products are of high-quality on the rugged terrain and coastal-regions of the Antarctic Peninsula and have good geospatial accuracy, but they also contain large errors on ice-covered terrain and we seek to minimise these artefacts. Conventional data correction techniques do not work so we have developed a method that significantly improves the dataset, smoothing the erroneous regions and hence creating a DEM with a pixel size of 100 m that will be suitable for many glaciological applications. We evaluate the new DEM using ICESat-derived elevations, and perform horizontal and vertical accuracy assessments based on GPS positions, SPOT-5 DEMs and the Landsat Image Mosaic of Antarctica (LIMA) imagery. The new DEM has a mean elevation difference of -4 m (± 25 m RMSE) from ICESat (compared to -13 m mean and ±97 m RMSE for the original ASTER GDEM), and a horizontal error of less than 2 pixels, although elevation accuracies are lower on mountain peaks and steep-sided slopes. The correction method significantly reduces errors on low relief slopes and therefore the DEM can be regarded as suitable for topographical studies such as measuring the geometry and ice flow properties of glaciers on the Antarctic Peninsula. The DEM is available for download from the NSIDC website: http://nsidc.org/data/nsidc-0516.html (doi:10.5060/D47P8W9D).
Cook, A. J.; Murray, T.; Luckman, A.; Vaughan, D. G.; Barrand, N. E.
Computer vision: automating DEM generation of active lava flows and domes from photos
NASA Astrophysics Data System (ADS)
Accurate digital elevation models (DEMs) form fundamental data for assessing many volcanic processes. We present a photo-based approach developed within the computer vision community to produce DEMs from a consumer-grade digital camera and freely available software. Two case studies, based on the Volc·n de Colima lava dome and the Puyehue CordÛn-Caulle obsidian flow, highlight the advantages of the technique in terms of the minimal expertise required, the speed of data acquisition and the automated processing involved. The reconstruction procedure combines structure-from-motion and multi-view stereo algorithms (SfM-MVS) and can generate dense 3D point clouds (millions of points) from multiple photographs of a scene taken from different positions. Processing is carried out by automated software (e.g. http://blog.neonascent.net/archives/bundler-photogrammetry-package/). SfM-MVS reconstructions are initally un-scaled and un-oriented so additional geo-referencing software has been developed. Although this step requires the presence of some control points, the SfM-MVS approach has significantly easier image acquisition and control requirements than traditional photogrammetry, facilitating its use in a broad range of difficult environments. At Colima, the lava dome surface was reconstructed from recent and archive images taken from light aircraft over flights (2007-2011). Scaling and geo-referencing was carried out using features identified in web-sourced ortho-imagery obtained as a basemap layer in ArcMap - no ground-based measurements were required. Average surface measurement densities are typically 10-40 points per m2. Over mean viewing distances of ~500-2500 m (for different surveys), RMS error on the control features is ~1.5 m. The derived DEMs (with 1-m grid resolution) are sufficient to quantify volumetric change, as well as to highlight the structural evolution of the upper surface of the dome following an explosion in June 2011. At Puyehue CordÛn-Caulle, images of the active lava flow were taken on foot from a ridge overlooking the flow. To assess the evolution of the flow front, two DEMs were derived from collections of ~400 images taken on different days. To scale and geo-reference the data, one image sequence was accompanied by simultaneous collection of a GPS track using a consumer handheld GPS unit; no control points were used. The second survey was then scaled and georeferenced to the first, using features identifiable in both image sets, giving an RMS error of ~0.22 m. DEM comparison then allows advance rates and mechanisms to be identified, and comparisons drawn with emplacement processes of basaltic flows. In both case studies, the SfM-MVS approach allowed DEM generation when access or lack of dedicated surveying equipment and expertise prevented standard techniques from being deployed.olima dome 2011: 3D point cloud data
James, M. R.; Varley, N. R.; Tuffen, H.
Research on optimal DEM cell size for 3D visualization of loess terraces
NASA Astrophysics Data System (ADS)
In order to represent the complex artificial terrains like loess terraces in Shanxi Province in northwest China, a new 3D visual method namely Terraces Elevation Incremental Visual Method (TEIVM) is put forth by the authors. 406 elevation points and 14 enclosed constrained lines are sampled according to the TIN-based Sampling Method (TSM) and DEM Elevation Points and Lines Classification (DEPLC). The elevation points and constrained lines are used to construct Constrained Delaunay Triangulated Irregular Networks (CD-TINs) of the loess terraces. In order to visualize the loess terraces well by use of optimal combination of cell size and Elevation Increment Value (EIV), the CD-TINs is converted to Grid-based DEM (G-DEM) by use of different combination of cell size and EIV with linear interpolating method called Bilinear Interpolation Method (BIM). Our case study shows that the new visual method can visualize the loess terraces steps very well when the combination of cell size and EIV is reasonable. The optimal combination is that the cell size is 1 m and the EIV is 6 m. Results of case study also show that the cell size should be at least smaller than half of both the terraces average width and the average vertical offset of terraces steps for representing the planar shapes of the terraces surfaces and steps well, while the EIV also should be larger than 4.6 times of the terraces average height. The TEIVM and results above is of great significance to the highly refined visualization of artificial terrains like loess terraces.
Zhao, Weidong; Tang, Guo'an; Ji, Bin; Ma, Lei
A DEM model for soft and hard rocks: Role of grain interlocking on strength
NASA Astrophysics Data System (ADS)
The Discrete Element Method (DEM) is increasingly used to simulate the behavior of rock. Despite their intrinsic capability to model fracture initiation and propagation starting from simple interaction laws, classical DEM formulations using spherical discrete elements suffer from an intrinsic limitation to properly simulate brittle rock behavior characterized by high values of UCS/TS ratio associated with non-linear failure envelopes, as observed for hard rock like granite. The present paper shows that the increase of the interaction range between the spherical discrete elements, which increases locally the density of interaction forces (or interparticle bonds), can overcome this limitation. It is argued that this solution represents a way to implicitly take into account the degree of interlocking associated to the microstructural complexity of rock. It is thus shown that increasing the degree of interlocking between the discrete elements which represent the rock medium, in addition to enhancing the UCS/TS ratio, results in a non-linear failure envelop characteristic of low porous rocks. This approach improves significantly the potential and predictive capabilities of the DEM for rock modeling purpose. A special emphasis is put on the model ability to capture the fundamental characteristics of brittle rocks in terms of fracture initiation and propagation. The model can reproduce an essential component of brittle rock failure, that is, cohesion weakening and frictional strengthening as a function of rock damage or plastic strain. Based on model predictions, it is finally discussed that frictional strengthening may be at the origin of the brittle ductile transition occurring at high confining pressures.
ScholtËs, Luc; DonzÈ, FrÈdÈric-Victor
Sensitivity of watershed attributes to spatial resolution and interpolation method of LiDAR DEMs in three distinct landscapes
NASA Astrophysics Data System (ADS)
study investigates scaling relationships of watershed area and stream networks delineated from LiDAR DEMs. The delineations are tested against spatial resolution, including 1, 5, 10, 25, and 50 m, and interpolation method, including Inverse Distance Weighting (IDW), Moving Average (MA), Universal Kriging (UK), Natural Neighbor (NN), and Triangular Irregular Networks (TIN). Study sites include Mosquito Creek, Scotty Creek, and Thomas Brook, representing landscapes with high, low, and moderate change in elevation, respectively. Results show scale-dependent irregularities in watershed area due to spatial resolution at Thomas Brook and Mosquito Creek. The highest sensitivity of watershed area to spatial resolution occurred at Scotty Creek, due to high incidence of LiDAR sensor measurement error and subtle changes in elevation. Length of drainage networks did not show a scaling relationship with spatial resolution, due to algorithmic complications of the stream initiation threshold. Stream lengths of main channels at Thomas Brook and Mosquito Creek displayed systematic increases in length with increasing spatial resolution, described through an average fractal dimension of 1.059. The scaling relationship between stream length and DEM resolution allows estimation of stream lengths from low-resolution DEMs in the absence of high-resolution DEMs. Single stream validation at Thomas Brook showed the 1 m DEM produced the lowest length error and highest spatial accuracy, at 3.7% and 71.3%, respectively. Single stream validation at Mosquito Creek showed the 25 m DEM produced the lowest length error, and the 1 m DEM the highest spatial accuracy, at 0.6% and 61.0%, respectively.
Goulden, T.; Hopkinson, C.; Jamieson, R.; Sterling, S.
A 3D DEM-LBM approach for the assessment of the quick condition for sands
NASA Astrophysics Data System (ADS)
We present a 3D numerical model to assess the quick condition (the onset of the boiling phenomenon) in a saturated polydisperse granular material. We use the Discrete Element Method (DEM) to study the evolution of the vertical intergranular stress in a granular sample subjected to an increasing hydraulic gradient. The hydrodynamic forces on the grains of the sample are computed using the Lattice Boltzmann Method (LBM). The principal assumption used is that grains remain at rest until the boiling onset. We show that the obtained critical hydraulic gradient is close to that defined in classical soil mechanics. To cite this article: M. Mansouri et al., C. R. Mecanique 337 (2009).
Mansouri, M.; Delenne, J.-Y.; El Youssoufi, M. S.; Seridi, A.
Generation of pixel-level resolution lunar DEM based on Chang'E-1 three-line imagery and laser altimeter data
NASA Astrophysics Data System (ADS)
Acquiring high resolution topography products of the Moon is an important issue for further lunar exploration. In this paper, we present a data processing flow of 3D reconstruction based on Chang'E-1 (CE-1) three-line imagery (120 m) and laser altimeter (LAM) data to acquire pixel-level resolution DEM. First, initial global disparity estimation was generated, and then corresponding points were acquired pixel-by-pixel by Adaptive Support-Weight Approach. A Least Square Image matching method was used to achieve sub-pixel accuracy, ultimately resulting in pixel-level resolution DEM (120 m). Global lunar 100 m DEM (GLD100 DEM) from LROC WAC stereo imagery is employed for comparison analysis and the mean elevation difference between two DEMs is less than 120 m. Experimental results show that the processing flow is effective and reliable for acquiring pixel-level DEM based on CE-1 data.
Zhang, Wuming; Zhang, Xiaobin; Chen, Yiming; Yan, Kai; Yan, Guangjian; Liu, Qiang; Zhou, Guoqing
DEM simulations of the evolution of fault zones in brittle-ductile layered rocks
NASA Astrophysics Data System (ADS)
The development of normal faults in brittle ductile layered rocks is modeled in this work using the Discrete Element Model (DEM) approach. The simulations were realized using the open source DEM package ESyS-Particle (https://launchpad.net/esys-particle/). The models consist of one cemented layer inside a cohesionless granular material above a basement fault in a gravity field. The cohesion of the cemented layer and the angle of the basement fault were varied. Different random packings of the material were used to estimate the effect of the material heterogeneity. Results show, that two structural domains exist, a graben domain and a precursor domain. In both of these domains, the variation in cohesion of the hard layer produces large differences in the structural evolution. As expected, the largest changes in fault gouge evolution occur when the increase in cohesion of the hard layer make the minimum principle stress become tensile. The main parameter that determines the amount of tectonic abrasion in the fault zones is the cohesion of the brittle layer. This leads to a gradual thinning of the layer with low cohesion and development of blocks and fragments in case of a relatively high cohesion. Thus, continuity of the sheared layer is higher in the rocks with low cohesion. The structural domain also affects the continuity of the brittle layer: in the precursor domain the brittle layer is more continuous than in the graben domain.
Raith, Alexander; Urai, Janos L.; Abe, Steffen
Rapid visualization of global image and dem based on SDOG-ESSG
NASA Astrophysics Data System (ADS)
Due to the limit of the two-dimension and small scale issues, it's impossible for the conventional planar and spherical global spatial grid to provide a unified real three-dimensional (3D) data model for Earth System Science research. The surface of the Earth is an important interface between lithosphere and atmosphere. Usually, the terrain should be added into the model in global changes and tectonic plates movement researches. However, both atmosphere and lithosphere are typical objects of three-dimension. Thus, it is necessary to represent and visualize the terrain in a real 3D mode. Spheroid Degenerated Octree Grid based Earth System Spatial Grid (SDOG-ESSG) not only solve the problem small-scale issues limited, but also solve the problem of two-dimension issues oriented. It can be used as real 3D model to represent and visualize the global image and DEM. Owing to the complex spatial structure of SDOG-ESSG, the visual efficiency of spatial data based on SDOG-ESSG is very low. Methods of layers and blocks data organization, as well as data culling, Level of Detail (LOD), and asynchronous scheduling, were adopted in this article to improve the efficiency of visualization. Finally, a prototype was developed for the quick visualization of global DEM and image based SDOG-ESSG.
Bo, H. G.; Wu, L. X.; Yu, J. Q.; Yang, Y. Z.; Xie, L.
Kinematic structure of the supergiant shell LMC 9 - I. The nebular complex DEM L208
NASA Astrophysics Data System (ADS)
This work describes an extensive and eminently observational study, carried out with an H? filter, of the kinematics of the ionized gas in the large emission region (220 pc) DEM L208 which is located in the south-east part of the Large Magellanic Cloud (LMC). The intention was to establish the region's general kinematic and morphological characteristics, and to analyse its possible association with a larger structure, aiming above all to contribute to the elaboration of a detailed global kinematics image of the LMC. The nebula's edges are well defined, with fairly regular Gaussian profiles, and can be represented by a systemic radial velocity of approximately 250 km s-1 for the brightest area of DEM L208. The radial velocity fields obtained present a main component with a well-defined profile, as well as other weaker components of larger speed, which may be indicative of expansion motion or of another layer of gas. In some regions we find evidence that the disturbance of the medium is due to stellar winds from the interior of the nebula; in others the profiles observed are found to be consistent with very intense stellar winds from Wolf-Rayet stars.
Oddone, M. A.; Ambrocio-Cruz, P.; Le Coarer, E.; Goldes, G. V.
Algorithms for using a DEM for mapping catchment areas of stream sediment samples
NASA Astrophysics Data System (ADS)
Algorithms are presented which use a digital elevation model (DEM) to create maps of catchment areas of stream sediment sample points, and to locate optimal sample point locations. Drainage flow directions are determined by the popular "D8" algorithm, which assigns the drainage from one point on the DEM grid to one of its eight adjacent neighbors. A new "drainage enforcement" algorithm is presented that insures drainage continuity through flat areas and out of depressions. This algorithm is based on the priority-first-search weighted-graph algorithm. Relatively simple methods for defining internal basins and incorporating digitized stream data are also discussed. All of the selected methods are robust, computationally efficient, and avoid many of the problems associated with other methods. In order to support this claim, the literature is reviewed and comparisons are made between the chosen methods and other methods. A full implementation has been created, and the Pascal source-code and Win95 executable program may be downloaded from the IAMG web site.
Jones, Richard
Open-Source MFIX-DEM Software for Gas-Solids Flows: Part II - Validation Studies
With rapid advancements in computer hardware and numerical algorithms, computational fluid dynamics (CFD) has been increasingly employed as a useful tool for investigating the complex hydrodynamics inherent in multiphase flows. An important step during the development of a CFD model and prior to its application is conducting careful and comprehensive verification and validation studies. Accordingly, efforts to verify and validate the open-source MFIX-DEM software, which can be used for simulating the gasñsolids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles, have been made at the National Energy Technology Laboratory (NETL). In part I of this paper, extensive verification studies were presented and in this part, detailed validation studies of MFIX-DEM are presented. A series of test cases covering a range of gasñsolids flow applications were conducted. In particular the numerical results for the random packing of a binary particle mixture, the repose angle of a sandpile formed during a side charge process, velocity, granular temperature, and voidage profiles from a bounded granular shear flow, lateral voidage and velocity profiles from a monodisperse bubbling fluidized bed, lateral velocity profiles from a spouted bed, and the dynamics of segregation of a binary mixture in a bubbling bed were compared with available experimental data, and in some instances with empirical correlations. In addition, sensitivity studies were conducted for various parameters to quantify the error in the numerical simulation.
Li, Tingwen
Region-growing segmentation to automatically delimit synthetic drumlins in 'real' DEMs
NASA Astrophysics Data System (ADS)
Mapping or 'delimiting' landforms is one of geomorphology's primary tools. Computer-based techniques, such as terrain segmentation, may potentially provide terrain units that are close to the size and shape of landforms. Whether terrain units represent landforms heavily depends on the segmentation algorithm, its settings and the type of underlying land-surface parameters (LSPs). We assess a widely used region-growing technique, i.e. the multiresolution segmentation (MRS) algorithm as implemented in object-based image analysis software, for delimiting drumlins. Supervised testing was based on five synthetic DEMs that included the same set of perfectly known drumlins at different locations. This, for the first time, removes subjectivity from the reference data. Five LSPs were tested, and four variants were computed for each using two pre- and post-processing options. The automated method (1) employs MRS to partition the input LSP into 200 ever coarser terrain unit patterns, (2) identifies the spatially best matching terrain unit for each reference drumlin, and (3) computes four accuracy metrics for quantifying the aerial match between delimited and reference drumlins. MRS performed best on LSPs that are regional, derived from a decluttered DEM and then normalized. Median scale parameters (SPs) for segments best delineating drumlins were relatively stable for the same LSP, but varied significantly between LSPs. Larger drumlins were generally delimited at higher SPs. MRS indicated high robustness against variations in the location and distribution of drumlins.
Eisank, Clemens; Smith, Mike; Hillier, John
Assessment of an ASTER-generated DEM for 2D hydrodynamic flood modeling
NASA Astrophysics Data System (ADS)
Flood modeling often provides inputs to flood hazard management. In the present work we studied the flooding characteristics in the data scarce region of the Lake Tana basin at the source of the Blue Nile River. The study required to integrate remote sensing, GIS with a two-dimensional (2D) module of the SOBEK flood model. The resolution of the topographic data in many areas, such as the Lake Tana region, is commonly too poor to support detailed 2D hydrodynamic modeling. To overcome such limitations, we used a Digital Elevation Model (DEM) which was generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image. A GIS procedure is developed to reconstruct the river terrain and channel bathymetry. The results revealed that a representation of the river terrain largely affects the simulated flood characteristics. Simulations indicate that effects of Lake Tana water levels propagate up to 13 km along the Ribb River. We conclude that a 15 m resolution ASTER DEM can serve as an input to detailed 2D hydrodynamic modeling in data scarce regions. However, for this purpose it is necessary to accurately reconstruct the river terrain geometry and flood plain topography based on ground observations by means of a river terrain model.
Tarekegn, Tesfaye Haimanot; Haile, Alemseged Tamiru; Rientjes, Tom; Reggiani, P.; Alkema, Dinand
Effect of cohesion on granular-fluid flows in spouted beds: PIV measurement and DEM simulations
NASA Astrophysics Data System (ADS)
In contrast to wet granular flows, the effect of cohesion on complex granular-fluid flows is intriguing but much challenging. The liquid bridges, forming between binary particles with the addition of a small amount of liquids, might significantly change the granular-fluid system due to both cohesion and lubrication effects. In this paper, a spouted bed, among various fluidization technologies, is particularly selected as a prototypical system for studying granular-fluid flows, since it can provide a quasi-steady flow pattern of granular particles, i.e., a core of upward granular-fluid flow called the "spout" and a surrounding region of downward quasi-static granular flow called the "annulus". Firstly, using self-developed particle image velocimetery (PIV) technique, the effects of cohesion on the spout-annulus interface (namely the spout width) and on the particle velocity profiles in distinct zones are examined. Further, the discrete element method (DEM), by incorporating liquid bridge adhesion into soft-sphere model, is established and used to predict the microdynamic behavior of particles in spouted beds. Finally, based on both experiments and DEM validation, the effects on the granular patterns in these two zones are comparatively discussed.
Zhu, Runru; LI, Shuiqing; Yao, Qiang
Micro relief parameters from high resolution DEMs as representative values for physical based soil erosion models
NASA Astrophysics Data System (ADS)
Field parameters, such as hydraulic roughness are indispensable for modeling soil erosion on a physical base. Established approaches to acquire parameters for hydraulic roughness are based on flow velocity, flow volume and the slope angle. Other methods refer to grain sizes affecting a volume flow as an indicator for roughness. This work presents a remote sensing approach to generate high resolution surface reconstructions of rough terrain in different scales. As the ability of producing high resolution digital elevation models (DEM) is rapidly increasing over the last years, the possibilities of morphometric analysis of micro reliefs are also constantly developing. Point spacings of very dense point clouds acquired with the help of terrestrial laserscanning or structure from motion are minimal. Thus, even small grain sizes and inhomogeneity can be identified in the DEMs. Surface models used for this study were acquired in advance and afterwards simulated flow and rainfall events. Resulting changes in surface roughness caused by fluvial erosion could be detected on bare soil and sparsely vegetated areas. To validate the measured roughness values flow velocities and flow volumes were regularly recorded during the events. This work aims to present a step forward to standardizing new methods in data acquisition in soil erosion modeling.
Neugirg, Fabian; Kaiser, Andreas; Haas, Florian; Veh, Georg; Schindewolf, Marcus; Schmidt, J¸rgen; Becht, Michael
DEM generation from digital photographs using computer vision: Accuracy and application
NASA Astrophysics Data System (ADS)
Data for detailed digital elevation models (DEMs) are usually collected by expensive laser-based techniques, or by photogrammetric methods that require expertise and specialist software. However, recent advances in computer vision research now permit 3D models to be automatically derived from unordered collections of photographs, and offer the potential for significantly cheaper and quicker DEM production. Here, we review the advantages and limitations of this approach and, using imagery of the summit craters of Piton de la Fournaise, compare the precisions obtained with those from formal close range photogrammetry. The surface reconstruction process is based on a combination of structure-from-motion and multi-view stereo algorithms (SfM-MVS). Using multiple photographs of a scene taken from different positions with a consumer-grade camera, dense point clouds (millions of points) can be derived. Processing is carried out by automated 'reconstruction pipeline' software downloadable from the internet. Unlike traditional photogrammetric approaches, the initial reconstruction process does not require the identification of any control points or initial camera calibration and is carried out with little or no operator intervention. However, such reconstructions are initially un-scaled and un-oriented so additional software has been developed to permit georeferencing. Although this step requires the presence of some control points or features within the scene, it does not have the relatively strict image acquisition and control requirements of traditional photogrammetry. For accuracy, and to allow error analysis, georeferencing observations are made within the image set, rather than requiring feature matching within the point cloud. Application of SfM-MVS is demonstrated using images taken from a microlight aircraft over the summit of Piton de la Fournaise volcano (courtesy of B. van Wyk de Vries). 133 images, collected with a Canon EOS D60 and 20 mm fixed focus lens, were used to create a ~1.6 km wide DEM covering the summit craters. When compared with a DEM constructed using close-range photogrammetry the SfM-MVS results showed an RMS error of 1.0 m. The overall precision of the project can be considered by ratioing this against the average viewing distance (1000 m). This relative precision of 1:1000 is in line with the results of other projects carried out over a range of spatial scales (down to ~0.1 m), so appears to be a characteristic expected achievable precision for the SfM-MVS approach. Consequently, over shorter viewing distances, absolute precisions increase - e.g. centimeter-level precisions for outcrop-scale studies where viewing distances may be expected to be of order 10 m. Although SfM-MVS cannot deliver the accuracy and precision of formal close-range photogrammetry, it can approach the results that are achievable from single stereo image pairs. However, the main advantages of the technique lie in the enhanced flexibility in image collection and automated processing, both of which significantly decrease the level of expertise required. When compared with terrestrial laser scanning at outcrop scales, the data collection time in the field can be reduced by ~80%. SfM-MVS data quality is sufficient for the technique to provide valuable DEMs of active flows and domes where access to (or for) modern surveying equipment is restricted.
James, M. R.; Robson, S.
Calibration and validation of DEM rolling and sliding friction coefficients in angle of repose and shear measurements
NASA Astrophysics Data System (ADS)
Pile formation and rotating drum experiments followed by DEM simulations using glass beads (1.5 and 3.0 mm diameter) and polyamide spheres (3.0 mm diameter) were conducted. A wide range of rotation velocities was tested (from 1 to 90 rpm), the drum fill degree was set to 50%. The material inclination angles obtained in pile formation experiments were comparable with low speed rotating drum tests. The experimentally obtained results were used to determine DEM friction coefficients. Both, good qualitative and good quantitative agreements between experiments and simulations were found for rotation speeds up to 5 rpm, whereas for higher rotation speeds small discrepancies were observed.
Frankowski, Piotr; Morgeneyer, Martin
Formation flying for along-track interferometric oceanographyóFirst in-flight demonstration with TanDEM-X
NASA Astrophysics Data System (ADS)
Beyond its primary mission objective, the TanDEM-X formation flying mission provides a unique test bed for demonstrating new SAR techniques such as Along-Track Interferometry (ATI) for ocean current measurement. In this paper we discuss the ATI formation control requirements and the limitations imposed by the implemented Helix-formation. We propose two ATI scenarios and verify their feasibility by means of software simulation and in-flight demonstration. In particular, flight results of the very first ATI experiment are presented, demonstrating the high potential of TanDEM-X for mapping ocean currents.
Kahle, Ralph; Runge, Hartmut; Ardaens, Jean-Sebastien; Suchandt, Steffen; Romeiser, Roland
Using DEMs to evaluate morphological change around an emergent vegetation patch over repeated hydrographs
NASA Astrophysics Data System (ADS)
Flume experiments tested a sand-gravel sediment mixture and two model emergent vegetation patches of varying stem density to explore changes in bed morphology around a patch when subjected to a series of repeated hydrographs. The wake area downstream of emergent vegetation patches is typically considered a region of sediment accumulation. However, the extent to which mixed size sediment transports and deposits around emergent vegetation patches remains poorly defined. This uncertainty is heightened by changes in bed morphology over large temporal scales and unsteady flow conditions. In these experiments unsteady flow hydrographs were discretized with 17 four-minute constant flow intervals with magnitudes modeled to fit the asymmetrical shape of the NRCS dimensionless unit hydrograph. Hydrographs were applied to a channel of mixed gravel and sand sediment in which a patch of emergent vegetation was fixed. The same hydrograph was repeated in each experiment and between hydrographs, a 2-hour baseflow was run to simulate lower flow periods and provide a flow history to the channel. Suspended and bedload sediment transport rates were measured during every flow interval of each hydrograph. After each hydrograph a detailed digital elevation model (DEM) was created to map the bed morphology and allow for DEM differencing. A unit bed adjustment parameter, ?b, is introduced to quantify the amount of reach-averaged channel change and monitor morphological stability over the scales of multiple hydrographs. Flow and sediment conditions were repeated for patches with sparse and dense stem densities. Results indicated that the total sediment yield over each hydrograph was reduced for both the sparse and dense model patches relative to unvegetated channel conditions. In the case of the sparse patch, the channel reached a dynamically stable state in one fewer hydrograph than when there was no patch present. A characteristic morphology developed downstream of the patch, with a mound of sediment accumulation forming within 10 patch diameters and significant ripple formation beyond this point farther downstream. The channel bed adjusted in a similar fashion for the dense patch, though the sediment mound was locally higher just downstream of the patch, not as extensive laterally, and dune formation was somewhat delayed and not as regular as for the sparse patch. More erosion was observed adjacent to the dense patch than for the sparse, consistent with flow acceleration due to increased channel blockage. Overall, the dense patch appeared to introduce more variability in the channel bed morphology, reflected by a larger range and standard deviation of bed elevations for the series of DEMs.
Waters, K. A.; Curran, J. C.
Implementation of large-scale landscape evolution modelling to real high-resolution DEM
NASA Astrophysics Data System (ADS)
We have developed a surface evolution model to be naturally integrated with 3D thermomechanical codes like SLIM-3D to study coupled tectonic-climate interaction. The resolution of the surface evolution model is independent of that of the underlying continuum box. The surface model follows the concept of the cellular automaton implemented on a regular Eulerian mesh. It incorporates an effective filling algorithm that guarantees flow direction in each cell, D8 search for flow directions, computation of discharges and bedrock incision. Additionally, the model implements hillslope erosion in the form of non-linear, slope-dependent diffusion. The model was designed to be employed not only to synthetic topographies but also to real Digital Elevation Models (DEM). In present work we report our experience with model implication to the 30-meter resolution ASTER GDEM of the Pamir orogen, in particular, to the segment of the Panj river. We start with calibration of the model parameters (fluvial incision and hillslope diffusion coefficients) using direct measurements of Panj incision rates and volumes of suspended sediment transport. Since the incision algorithm is independent on hillslope processes, we first adjust the incision parameters. Power-law exponents of the incision equation were evaluated from the profile curvature of the main Pamir rivers. After that, incision coefficient was adjusted to fit the observed incision rate of 5 mm/y. Once the model results are consistent with the measured data, the calibration of hillslope processes follows. For given critical slope, diffusivity could be fitted to match the observed sediment discharge. Applying of surface evolution model to real DEM reveals specific problems which do not appear when working with synthetic landscapes. One of them is the noise of the satellite-measured topography. In particular, due to the non-vertical observation perspective, satellite may not be able to detect the bottom of the river channel, especially for deep incised rivers. Accordingly, the DEM has to be pre-processed in order to avoid huge errors in the incision algorithm. This pre-processing includes removal of outliers and some smoothing and interpolation along the flow direction. Another problem is that true valley size may be much wider than single grid-size. That is important to consider since usual flow-direction algorithms operate with zero-width (i.e., single grid-size) channels. If applied literally to such a wide river valley, they result in a tine and deep canyon inside the initial valley. To avoid this unnatural behaviour, accumulated water discharge has to be effectively redistributed over the whole valley.
Schroeder, S.; Babeyko, A. Y.
Semi-automated extraction of landslides in Taiwan based on SPOT imagery and DEMs
NASA Astrophysics Data System (ADS)
The vast availability and improved quality of optical satellite data and digital elevation models (DEMs), as well as the need for complete and up-to-date landslide inventories at various spatial scales have fostered the development of semi-automated landslide recognition systems. Among the tested approaches for designing such systems, object-based image analysis (OBIA) stepped out to be a highly promising methodology. OBIA offers a flexible, spatially enabled framework for effective landslide mapping. Most object-based landslide mapping systems, however, have been tailored to specific, mainly small-scale study areas or even to single landslides only. Even though reported mapping accuracies tend to be higher than for pixel-based approaches, accuracy values are still relatively low and depend on the particular study. There is still room to improve the applicability and objectivity of object-based landslide mapping systems. The presented study aims at developing a knowledge-based landslide mapping system implemented in an OBIA environment, i.e. Trimble eCognition. In comparison to previous knowledge-based approaches, the classification of segmentation-derived multi-scale image objects relies on digital landslide signatures. These signatures hold the common operational knowledge on digital landslide mapping, as reported by 25 Taiwanese landslide experts during personal semi-structured interviews. Specifically, the signatures include information on commonly used data layers, spectral and spatial features, and feature thresholds. The signatures guide the selection and implementation of mapping rules that were finally encoded in Cognition Network Language (CNL). Multi-scale image segmentation is optimized by using the improved Estimation of Scale Parameter (ESP) tool. The approach described above is developed and tested for mapping landslides in a sub-region of the Baichi catchment in Northern Taiwan based on SPOT imagery and a high-resolution DEM. An object-based accuracy assessment is conducted by quantitatively comparing extracted landslide objects with landslide polygons that were visually interpreted by local experts. The applicability and transferability of the mapping system are evaluated by comparing initial accuracies with those achieved for the following two tests: first, usage of a SPOT image from the same year, but for a different area within the Baichi catchment; second, usage of SPOT images from multiple years for the same region. The integration of the common knowledge via digital landslide signatures is new in object-based landslide studies. In combination with strategies to optimize image segmentation this may lead to a more objective, transferable and stable knowledge-based system for the mapping of landslides from optical satellite data and DEMs.
Eisank, Clemens; Hˆlbling, Daniel; Friedl, Barbara; Chen, Yi-Chin; Chang, Kang-Tsung
Turbidity Current Transport using DEM and FEM: a Hybrid Lagrangian-Eulerian Approach
NASA Astrophysics Data System (ADS)
In this work we describe a contribution to the study of turbidity transport in scales smaller than TFM (two-fluid models), The intent of the work, part of a large scale simulation project, is to assess local, small scale parameters and their upscaling. The hybrid model is based on a Lagrangian-Eulerian approach under a class of the so called Unresolved Discrete Particle Method (UDPM). In this approach, a Lagrangian description is used for the particle system employing the Discrete Element Method (DEM) while a fixed Eulerian mesh is used for the fluid phase modeled by finite element method (FEM), Fluid motion is governed by Navier-Stokes equations which are solved by an appropriate FEM implementation. Closure equation are used to compute drag and lift forces over the particles in the DEM framework. Volume averaged momentum sink terms are included in the fluid equations. The resulting coupled DEM-FEM model is integrated in time with a subcycling scheme. The aforementioned scheme was applied in the simulation of a sedimentation basin as depicted in figures 1 and 2 to investigate flow and deposition features of the suspension in a finer scale. For this purpose a submodel of the basin was generated. Mapping variables back and forth the Eulerian (finite element) model and the Lagrangian (discrete element) model were performed during the subcycled integration of the hybrid model. References: [1] Hoomans, B.P.B., Kuipers, J.A.M., Swaaij, van W.P.M," Granular dynamics Simulation of segregation phenomena in bubbling gas-fluidised beds", Powder Technology, V 109, Issues 1-3, 3 April 2000, pp 41-48; [2] Cho, S.H., Choi,H.G, Yoo, J.Y.,"Direct numerical simulation of fluid flow laden with many particles", International Journal of Multiphase Flow, V 31, Issue 4, April 2005, pp 435-451;; Sedimentation basin: sectioning the turbidity plume in the Eulerian FE model for setting up the discrete particle model. ; Sedimentation Basin: section of the turbidity plume displaying the generated discrete particle model underneath.
Alves, J. L.; Guevara, N. O., Jr.; Silva, C. E.; Alves, F. T.; Gazoni, L. C.; Coutinho, A.; Camata, J.; Elias, R. N.; Paraizo, P.
Volcanic Landform Classification of Iwate Volcano from DEM-Derived Thematic Maps
NASA Astrophysics Data System (ADS)
Over the last three decades, digital elevation models (DEMs) have been developed as surface data instead of contour lines to allow numerical analysis or modeling of terrain by computer. DEMs have allowed the development of algorithms to rapidly derive slope, relief, convexity, concavity and aspect of any points of surface, and also have allowed the definition of a number of new morphometric measures i.e. openness (Yokoyama et al., 2002). Openness is an angular measure of the relation between surface relief and horizontal distance. Openness has two viewer perspectives. Positive values, expressing openness above the surface, are high for convex forms, whereas negative values describe this attribute below the surface and are high for concave forms. The emphasis of terrain convexity and concavity in openness maps facilitates the interpretation of landforms on the Earth_fs surface. Prima et al. (2003) proposed automated landform classification using openness and slope with genetic factors. This method had been proved to produce good classification for constructional (alluvial plains, alluvial fans and volcanoes) and erosional (hills and mountains) landforms. The capability of this method to classify landforms from DEMs with genetic factors is important because it allows landform evolution to be numerically analyzed. In this study, we adopted this method to classify volcanic landforms of Iwate Volcano from Honshu, Japan, where volcanic landforms were categorized referring to geological map of Iwate Volcano (Doi, 2000). This process took three steps. First, the characteristic of each category was evaluated against the mean and standard deviation of slope, and both positive and negative openness, in two dimensional feature spaces. Second, the characteristic of each category were observed and the combinations of mean and standard deviation of slope and openness showing high separabilities were selected. We found that the standard deviation of slope, positive and negative openness yielded high separabilities of each category and indicated consistency between the trend of categories_f distribution and their geological successions. Third, Mahalanobis distance was used as classification rule to automatically classify the volcanic landforms of Iwate Volcano with those categories. The result shows fine interpretation of volcanic landforms of Iwate Volcano according to their geological successions. The northeastern sector of Iwate Volcano that has relatively young strata was clearly identified against other sectors of the volcano. Although some misclassification occurred in places where the ages of landform formation are relatively close, we considered that the present result is provisionally acceptable because the classified landforms in major accurately replicated many components of volcanic landforms of Iwate Volcano.
Prima, A. O.; Yoshida, T.
3DEM Loupe: Analysis of macromolecular dynamics using structures from electron microscopy.
Electron microscopy (EM) provides access to structural information of macromolecular complexes in the 3-20 ≈ resolution range. Normal mode analysis has been extensively used with atomic resolution structures and successfully applied to EM structures. The major application of normal modes is the identification of possible conformational changes in proteins. The analysis can throw light on the mechanism following ligand binding, protein-protein interactions, channel opening and other functional macromolecular movements. In this article, we present a new web server, 3DEM Loupe, which allows normal mode analysis of any uploaded EM volume using a user-friendly interface and an intuitive workflow. Results can be fully explored in 3D through animations and movies generated by the server. The application is freely available at http://3demloupe.cnb.csic.es. PMID:23671335
Nogales-Cadenas, R; Jonic, S; Tama, F; Arteni, A A; Tabas-Madrid, D; V·zquez, M; Pascual-Montano, A; Sorzano, C O S
Modeling Particle Rolling Behavior by the Modified Eccentric Circle Model of DEM
NASA Astrophysics Data System (ADS)
This study proposes a modified eccentric circle model to simulate the rolling resistance of circle particles through the distinct element method (DEM) simulation. The proposed model contains two major concepts: eccentric circle and local rotational damping. The mass center of a circular particle is first adjusted slightly for eccentricity to provide rotational stiffness. Local rotational damping is adopted to dissipate energy in the rotational direction. These associated material parameters can be obtained easily from the rolling behavior of one rod. This study verifies the proposed model with the repose angle tests of chalk rod assemblies, and the simulated results were satisfactory. Simulations using other existing models were also conducted for comparison, showing that the proposed model achieved better results. A landslide model test was further simulated, and this simulation agreed with both the failure pattern and the sliding process. In conclusion, particle rolling simulation using the proposed model appears to approach the actual particle trajectory, making it useful for various applications.
Chang, Yi-Long; Chen, Tsung-Hsien; Weng, Meng-Chia
Study of forest surface-fire spread simulation based on DEM
NASA Astrophysics Data System (ADS)
This paper uses the McArthur forest fire spread model, takes Visual C++ and OpenGL(Open Graphics Library) development kit, and experiments on the region of the Zhejiang Province Linan by using this city 1: 50000 DEM(Digital Elevation Model) data, investigations data of forest resources, unifies the real-time meteorological data, and researches the method of forest-fire spread simulation based on the 3D(three-dimension), which studies Forest fire production and the spread simulator method with its related algorithm in emphasis. The paper takes the forest fire production and spread method as the foundation to propose and design six algorithms to successively simulate the forest fire spread. Respectively: The fire that spreads in different directions algorithm, distributed fire points algorithm, scene of a fire region computation algorithm, mapping fire particle algorithm, flame production algorithm, and billboard technology application algorithm.
Xu, Ai-jun; Li, Qing-quan
DEM analysis of effects of particle properties and mixing conditions on particle attachment processes
NASA Astrophysics Data System (ADS)
The attachment of autoadhesive fine particles onto a large carrier particle in a vibrating container is investigated using a discrete element method (DEM) to determine the influence of the particle properties and vibration conditions. The contact number (number of fine particles contacting the carrier), coverage ratio (ratio of the contact number to that for complete monolayer coverage) and contact ratio (ratio of the contact number to the number of fine particles) are introduced to evaluate the attachment performance. The contact number increases with increasing work of adhesion, decreasing container size and increasing number of fine particles. The contact ratio decreases as the number of fine particles is increased. The coverage ratio increases as the carrier size is decreased.
Yang, Jiecheng; Wu, Chuan-Yu; Adams, Michael
3DEM Loupe: analysis of macromolecular dynamics using structures from electron microscopy
Electron microscopy (EM) provides access to structural information of macromolecular complexes in the 3ñ20 ≈ resolution range. Normal mode analysis has been extensively used with atomic resolution structures and successfully applied to EM structures. The major application of normal modes is the identification of possible conformational changes in proteins. The analysis can throw light on the mechanism following ligand binding, proteinñprotein interactions, channel opening and other functional macromolecular movements. In this article, we present a new web server, 3DEM Loupe, which allows normal mode analysis of any uploaded EM volume using a user-friendly interface and an intuitive workflow. Results can be fully explored in 3D through animations and movies generated by the server. The application is freely available at http://3demloupe.cnb.csic.es.
Nogales-Cadenas, R.; Jonic, S.; Tama, F.; Arteni, A. A.; Tabas-Madrid, D.; Vazquez, M.; Pascual-Montano, A.; Sorzano, C. O. S.
Open Source MFIX-DEM Software for Gas-Solids Flows: Part 1 - Verification Studies
With rapid advancements in computer hardware, it is now possible to perform large simulations of granular flows using the Discrete Element Method (DEM). As a result, solids are increasingly treated in a discrete Lagrangian fashion in the gasñsolids flow community. In this paper, the open-source MFIX-DEM software is described that can be used for simulating the gasñsolids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles. This method is referred to as the continuum discrete method (CDM) to clearly make a distinction between the ambiguity of using a Lagrangian or Eulerian reference for either continuum or discrete formulations. This freely available CDM code for gasñsolids flows can accelerate the research in computational gasñsolids flows and establish a baseline that can lead to better closures for the continuum modeling (or traditionally referred to as two fluid model) of gasñsolids flows. In this paper, a series of verification cases is employed which tests the different aspects of the code in a systematic fashion by exploring specific physics in gasñsolids flows before exercising the fully coupled solution on simple canonical problems. It is critical to have an extensively verified code as the physics is complex with highly-nonlinear coupling, and it is difficult to ascertain the accuracy of the results without rigorous verification. These series of verification tests set the stage not only for rigorous validation studies (performed in part II of this paper) but also serve as a procedure for testing any new developments that couple continuum and discrete formulations for gasñsolids flows.
Garg, Rahul; Galvin, Janine; Li, Tingwen; Pannala, Sreekanth
Open-source MFIX-DEM software for gas-solids flows: Part 1 - Verification studies
With rapid advancements in computer hardware, it is now possible to perform large simulations of granular flows using the Discrete Element Method (DEM). As a result, solids are increasingly treated in a discrete Lagrangian fashion in the gasñsolids flow community. In this paper, the open-source MFIX-DEM software is described that can be used for simulating the gasñsolids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles. This method is referred to as the continuum discrete method (CDM) to clearly make a distinction between the ambiguity of using a Lagrangian or Eulerian reference for either continuum or discrete formulations. This freely available CDM code for gasñsolids flows can accelerate the research in computational gasñsolids flows and establish a baseline that can lead to better closures for the continuum modeling (or traditionally referred to as two fluid model) of gasñsolids flows. In this paper, a series of verification cases is employed which tests the different aspects of the code in a systematic fashion by exploring specific physics in gasñsolids flows before exercising the fully coupled solution on simple canonical problems. It is critical to have an extensively verified code as the physics is complex with highly-nonlinear coupling, and it is difficult to ascertain the accuracy of the results without rigorous verification. These series of verification tests set the stage not only for rigorous validation studies (performed in part II of this paper) but also serve as a procedure for testing any new developments that couple continuum and discrete formulations for gasñsolids flows.
Garg, Rahul; Galvin, Janine; Li, Tingwen; Pannala, Sreekanth
Upscaling water cycle parameters using geomorphometric terrain parameters and topographic indices derived from interferometric DEM
NASA Astrophysics Data System (ADS)
For assessing a regional water balance in boreal landscapes the extend to which evapo-transpiration is subject to spatial variations needs to be known. Water cycle parameters such as transpiration rates of vegetation are depending on both the vegetation type and hydro-pedologic stand conditions since poor soil drainage respective seasonal soil drought affect water consumption by vegetation. The spatial distribution of the pristine boreal vegetation types can be obtained by SAR or optical remote sensing sensors on a regional scale. Many works have been dealing with this subject in the past and it is widely known how remote sensing can contribute to vegetation mapping. To assess hydro-pedologic stand conditions on a regional scale an alternative method is required. Our approach to resolve this problem is based on the fact that soil water status is essentially a function of topographic properties. For that reason morphometric terrain parameters derived from a Digital Elevation Model (DEM) has been used to indicate regions with homogeneous hydro-pedologic stand conditions, so called "hydropedotopes". To delineate the required hydropedotopes two indicators pertaining to soilwater status and pedo-hydrology were derived from InSAR DEM: (1) The wetness-index and (2) the vertical distance to streams and bottom lines. In a further step the resulting map of hydropedotopes is intersected with a remote sensing derived map of the actual spatial distribution of the boreal vegetation types. This step results in a map which marks out landscape units of homogeneous properties in terms of vegetation type and hydro-pedologic conditions which is the basis for upscaling canopy transpiration measurements. From our approach which uses in addition to conventional remote sensing data the results of an automated digital terrain analysis we expect a substantially enhanced knowledge of the spatial variability of water flux rates conditional on canopy transpiration. The process of our approach at a glance is illustrated.
Etzrodt, N.; Zimmermann, R.; Conrad, O.
Studying Glacial Melt Processes Using Sub-Centimeter dem Extraction and Digital Close-Range Photogrammetry
NASA Astrophysics Data System (ADS)
Glaciers are sensitive to climatic variation and a particular developing area of investigation is in the field of "cryoconite", referring to dustlike residues which form on the glacier surface. Cryoconite absorbs the Sun's shortwave energy, accelerates ice melt and because of the localised distribution of dust creates localised melting which is highly spatially variable. There is therefore a need to quantify the detailed topographic surface of ice and measure its variability through time. This paper describes the use of close range photogrammetry to reconstruct the glacier surface at the sub-centimetre or micro scale, an approach which may allow the relationship between cryoconite and ice surface properties to be explored over either space or time. The field campaign was conducted at Midtre LovÈnbreen, Svalbard (78.88∞ North 12.08∞ East), during the summer of 2010 and executed using simple equipment and procedures. A simple and ageing Nikon 5400 5 MP camera was used to acquire all imagery, proving sufficiently robust for the challenging field environment. The camera was handheld approximately 1.6 m above the ice surface, providing an oblique perspective. Images were acquired at three different camera/object distances, each generating coverage occupying three different areas. All imagery was processed using the commercial photogrammetric package PhotoModeler Scanner, generating threedimensional point clouds consisting of many thousands of XYZ coordinates, each colour-coded. It had been feared that lack of texture in the ice surface combined with differing specular reflections in each image would compromise the DEM generation process. Results were better than expected, although DEM quality proved to be variable depending on ice cleanliness and more significantly, the degree of obliquity of the image pairs. Despite these differences, digital close-range photogrammetry has proven to be a useful technique to reconstruct the glacier's surface to sub-centimeter precision. Moreover, the method is providing glacial scientists with new data to examine the relationship between cryoconite, ice surface roughness and melt processes.
Sanz-Ablanedo, E.; Chandler, J. H.; Irvine-Fynn, T. D. L.
Quality of DEMs derived from Kite Aerial Photogrammety System: a case study of Dutch coastal environments.
NASA Astrophysics Data System (ADS)
Coastal protection is one of the main challenges for the Netherlands, where a large proportion of anthropogenic activity is located below sea level (both residential and economic). The Dutch government is implementing an innovative method of coastal replenishment using natural waves and winds to relocate sand from one side to the other of the country. This requires close monitoring of the spatio-temporal evolution of beaches in order to correctly model the future direction and amount of sand movement. To do so -on the onshore beach- we tested a Kite-Aerial Photography System for monitoring the beach dynamics at Zandmotor (http://www.dezandmotor.nl/en-GB/). The equipment used for data collection were a commercial DSLR camera (Nikon D7000 with a 20mm lens), gyro-levelled rig, Sutton Flowform 16 kite and Leica GNSS Viva GS10, with GSM connection to the Dutch geodetic network. We flew using a 115 m line with an average inclination of 40 to 45∞; this gave a camera vertical distance of ~80 m and pixel size of ~20 mm. The methodology follows that of Smith et al. (2009), and of Paron & Smith (2013), applied to a highly dynamic environment with low texture and small relief conditions. Here we present a comparison of the quality of the digital elevation model (DEM) generated from the same dataset using two different systems: Structure from Motion (SfM) using Agisoft Photoscan Pro and traditional photogrammetry using Leica Photograpmmetry Suite. In addition the outputs from the two data processing methods are presented, including both an image mosaic and DEM, and highlighting pros and cons of both methods. References Smith, M. J. et al. 2009. High spatial resolution data acquisition for the geosciences: kite aerial photography. ESPL, 34(1), 155-161. Paron, P., Smith, M.J. 2013. Kite aerial photogrammetry system for monitoring coastal change in the Netherlands. 8th IAG International Conference on Geomorphology, Paris, August.
Paron, Paolo; Smith, Mike J.; Anders, Niels; Meesuk, Vorawit
An Adaptive Integration Model of Vector Polyline to DEM Data Based on Spherical Degeneration Quadtree Grids
NASA Astrophysics Data System (ADS)
Traditional geometry-based approach can maintain the characteristics of vector data. However, complex interpolation calculations limit its applications in high resolution and multi-source spatial data integration at spherical scale in digital earth systems. To overcome this deficiency, an adaptive integration model of vector polyline and spherical DEM is presented. Firstly, Degenerate Quadtree Grid (DQG) which is one of the partition models for global discrete grids, is selected as a basic framework for the adaptive integration model. Secondly, a novel shift algorithm is put forward based on DQG proximity search. The main idea of shift algorithm is that the vector node in a DQG cell moves to the cell corner-point when the displayed area of the cell is smaller or equal to a pixel of screen in order to find a new vector polyline approximate to the original one, which avoids lots of interpolation calculations and achieves seamless integration. Detailed operation steps are elaborated and the complexity of algorithm is analyzed. Thirdly, a prototype system has been developed by using VC++ language and OpenGL 3D API. ASTER GDEM data and DCW roads data sets of Jiangxi province in China are selected to evaluate the performance. The result shows that time consumption of shift algorithm decreased about 76% than that of geometry-based approach. Analysis on the mean shift error from different dimensions has been implemented. In the end, the conclusions and future works in the integration of vector data and DEM based on discrete global grids are also given.
Zhao, X. S.; Wang, J. J.; Yuan, Z. Y.; Gao, Y.
Capturing Micro-topography of an Arctic Tundra Landscape through Digital Elevation Models (DEMs) Acquired from Various Remote Sensing Platforms
NASA Astrophysics Data System (ADS)
The need to improve the spatial and temporal scaling and extrapolation of plot level measurements of ecosystem structure and function to the landscape level has been identified as a persistent research challenge in the arctic terrestrial sciences. Although there has been a range of advances in remote sensing capabilities on satellite, fixed wing, helicopter and unmanned aerial vehicle platforms over the past decade, these present costly, logistically challenging (especially in the Arctic), technically demanding solutions for applications in an arctic environment. Here, we present a relatively low cost alternative to these platforms that uses kite aerial photography (KAP). Specifically, we demonstrate how digital elevation models (DEMs) were derived from this system for a coastal arctic landscape near Barrow, Alaska. DEMs of this area acquired from other remote sensing platforms such as Terrestrial Laser Scanning (TLS), Airborne Laser Scanning, and satellite imagery were also used in this study to determine accuracy and validity of results. DEMs interpolated using the KAP system were comparable to DEMs derived from the other platforms. For remotely sensing acre to kilometer square areas of interest, KAP has proven to be a low cost solution from which derived products that interface ground and satellite platforms can be developed by users with access to low-tech solutions and a limited knowledge of remote sensing.
Vargas, S. A., Jr.; Tweedie, C. E.; Oberbauer, S. F.
DEM Response A nalysis of Buried Pipelines Crossing Faults and Proposal for a Simplified Method to Estimate Allowable Fault Displacements
This paper investigates the behavior of polyvinyl chlo- ride and ductile iron pipelines in relation to surface fault displacements using the Discrete Element Method (DEM) and proposes a method to estimate the allowable fault displacements. When modeling pipes and joints, the nonlinear material properties and joint characteristics (allowing detachment at the joints) are considered. Under a given set of various
Yasuko Kuwata; Shiro Takada; Radan Ivanov
Atmosphere sounding by GPS radio occultation: First results from TanDEM-X and comparison with TerraSAR-X
NASA Astrophysics Data System (ADS)
On 21 June 2010 the TerraSAR-X satellite was joined by the TanDEM-X satellite. A Global Positioning System (GPS) radio occultation (RO) experiment using the twin satellites has been carried out to estimate the precision of GPS atmospheric soundings. For the Day Of Year (DOY) 330-336, 2011, we analyze phase and amplitude data recorded by GPS receivers separated by a few hundred meters in a low earth orbit and derive collocated atmospheric refractivity profiles. In the altitude range 10-20 km the standard deviation between TerraSAR-X and TanDEM-X refractivity does not exceed 0.15%. The standard deviation is rapidly increasing for lower and higher altitudes; close to the surface and at an altitude of 30 km the standard deviation reaches 0.8% and 0.5%, respectively. Systematic deviations between TerraSAR-X and TanDEM-X refractivity in the considered altitude range (0-30 km) are negligible. The results confirm the anticipated high precision of the GPS RO technique. However, the difference in the retrieved refractivity in the lower troposphere for different Open Loop (OL) signal tracking parameters, altered onboard TanDEM-X for DOY 49-55, 2012, calls for an in depth analysis. At the moment we can not exclude that a potential bias in the OL Doppler model introduces a bias in our retrieved refractivity at altitudes <8 km.
Zus, Florian; Grunwaldt, Ludwig; Heise, Stefan; Michalak, Grzegorz; Schmidt, Torsten; Wickert, Jens
Use of an up-scaled DEM model for analysing the behaviour of a shallow foundation on a model slope
This paper presents a methodological approach for the DEM modelling of geotechnical problems. The approach is based on quite general principles, which are illustrated with reference to a specific problem, i.e. the reproduction of a physical model of a foundation on a sandy slope. The approach mainly consists in the reproduction of the involved soil using a small, but statistically
Fabio Gabrieli; Simonetta Cola; Francesco Calvetti
DEM analysis for AIA/SDO EUV channels using a probabilistic approach to the spectral inverse problem
NASA Astrophysics Data System (ADS)
The Atmospheric Imaging Assembly (AIA) for the Solar Dynamics Observatory (SDO) mis-sion is designed to observe the Sun from the photosphere to the flaring corona. These data have to improve our understanding of processes in the solar atmosphere. The differential emis-sion measure (DEM) analysis is one of the main methods to derive information about coronal optically thin plasma characteristics from EUV and SXR emission. In this work we analyze AIA/SDO EUV channels to estimate their ability to reconstruct DEM(T) distributions. We use an iterative method (called Bayesian iterative method, BIM) within the framework of a probabilistic approach to the spectral inverse problem for determining the thermal structures of the emitting plasma sources (Goryaev et al., submitted to AA). The BIM is an iterative procedure based on Bayes' theorem and used for the reconstruction of DEM profiles. Using the BIM algorithm we performed various numerical tests and model simulations demonstrating abilities of our inversion approach for DEM analysis with AIA/SDO EUV channels.
Goryaev, Farid; Parenti, Susanna; Hochedez, Jean-FranÁois; Urnov, Alexander
A generic procedure for automatically segmenting landforms into landform elements using DEMs, heuristic rules and fuzzy logic
A robust new approach for describing and segmenting landforms which is directly applicable to precision farming has been developed in Alberta. The model uses derivatives computed from DEMs and a fuzzy rule base to identify up to 15 morphologically defined landform facets. The procedure adds several measures of relative landform position to the previous classification of Pennock et al. (Geoderma
R. A. MacMillan; W. W. Pettapiece; S. C. Nolan; T. W. Goddard
Comparison of SIFT and SURF based DEM extraction approaches on a GEOEYE-1 satellite stereo-pair
NASA Astrophysics Data System (ADS)
A MATLAB module for Digital Elevation Model (DEM) extraction from Very High Resolution (VHR) satellite stereo-pair imagery is used to compare the efficiency of two well established feature detection and description algorithms. A procedure for parallel processing of cascading image tiles is used for handling the large datasets requirements of VHR satellite imagery. Scale-Invariant Feature Transform (SIFT) and Speeded Up Robust Features (SURF) algorithms are used to detect potentially tentative feature matches in the members of the stereo-pair. The resulting feature pairs are filtered using the RANdom SAmple Consensus (RANSAC) algorithm by using a variable distance threshold. Finally, tentative feature matches are converted to point cloud ground coordinates for DEM generation. A 0.5 m ◊ 0.5 m Geoeye-1 stereo-pair acquired over an area of 25 km2 in the island of Crete, Greece is used as input for the module. The resulting 2 m ◊ 2 m DEMs has superior detail over previously developed 2 m and 5 m DEMs that are used as reference, and yields a Root Mean Square Error (RMSE) of about 1 m compared to ground truth measurements. Results suggest that SURF's superior runtime performance outweighs the slightly better feature quality attained with SIFT.
Daliakopoulos, Ioannis; Tsanis, Ioannis
<5cm Ground Resolution DEMs for the Atacama Fault System (Chile), Acquried With the Modular Airborne Camera System (MACS)
NASA Astrophysics Data System (ADS)
A primary step towards assessing time and size of future earthquakes is the identification of earthquake recurrence patterns in the existing seismic record. Geologic and geomorphic data are commonly analyzed for this purpose, reasoned by the lack of sufficiently long historical or instrumental seismic data sets. Until recently, those geomorphic data sets encompassed field observation, local total station surveys, and aerial photography. Over the last decade, LiDAR-based high-resolution topographic data sets became an additional powerful mean, contributing distinctly to a better understanding of earthquake rupture characteristics (e.g., single-event along-fault slip distribution, along-fault slip accumulation pattern) and their relation to fault geometric complexities. Typical shot densities of such data sets (e.g., airborne-LiDAR data along the San Andreas Fault) permit generation of digital elevation models (DEM) with <50 cm ground resolution, sufficient for depiction of meter-scale tectonic landforms. Identification of submeter-scale features is however prohibited by DEM resolution limitation. Here, we present a high-resolution topographic and visual data set from the Atacama fault system near Antofagasta, Chile. Data were acquired with Modular Airborne Camera System (MACS) - developed by the DLR (German Aerospace Center) in Berlin, Germany. The photogrammetrically derived DEM and True Ortho Images with <5cm ground resolution permit identification of very small-scale geomorphic features, thus enabling fault zone and earthquake rupture characterization at unprecedented detail. Compared to typical LiDAR-DEM, ground resolution is increased by an order of magnitude while the spatial extend of these data set is essentially the same. Here, we present examples of the <5cm resolution data set (DEM and visual results) and further explore resolution capabilities and potential with regards to the aforementioned tectono-geomorphic questions.
Zielke, O.; Victor, P.; Oncken, O.; Bucher, T. U.; Lehmann, F.
Characterization of active fault scarps from medium to high resolution DEM: case studies from Central and Southern Apennines (Italy)
NASA Astrophysics Data System (ADS)
We identify geo-morphometric features of active fault scarps in Italy through a semiautomatic processing using GIS. Medium to high resolution DEM was used to characterize the geometry, structural, and erosive elements of two seismogenic normal faults in Central and Southern Apennines. The Pettino fault in L'Aquila area was detected using a 1 m pixel DEM derived from airborne LiDAR survey (Friuli Venezia Giulia Civil Protection). For the Castrovillari fault in northern Calabria region was used a 4 m pixel DEM (Regional Cartography Office of Regione Calabria). Scarp segments are region of planar discontinuities identified by selected values of DEM-derived Terrain Ruggedness Index (TRI) and Vector Ruggedness Measure (VRM). These planar discontinuities corresponds to landscape features such as, river terraces, roads scarps, and other natural or human features. The discrimination between these features have been accomplished overlaying extracted features on aerial photograph, geological and geomorphologic maps and in situ survey. After that, we perform the quantitative and statistical analysis of these areas identified as "fault scarps". The identification of elements relative to the scarps (e.g. base, crest, slope) is then obtained to derive the estimate of parameters describing the fault: altitude, height of the scarp, length, slope and aspect, Terrain Ruggedness Index (TRI) and Vector Ruggedness Measure (VRM). The spatial distribution of the extracted values was obtained through their statistical analysis. We analyze scarp parameters variations along the whole scarp extent, such as strike value from aspect variations, slope and profile curvature differences as indicators of tectonic and/or erosion activity. The combined analysis of the DEM-derived parameters allows us to (a) define aspects of three-dimensional scarp geometry, (b) decipher its geomorphological significance, and (c) estimate the long-term slip rate.
Brunori, C.; Cinti, F. R.; Ventura, G.
Evaluation of terrain datasets for LiDAR data thinning and DEM generation for watershed delineation applications
NASA Astrophysics Data System (ADS)
Watershed delineation based on Digital Elevation Models (DEM) is currently a standard practice in hydrologic studies. Efforts to develop DEMs of high resolution continues to take place, although the advantages of increasing the accuracy of the results are partially offset by the increased file size, difficulty to handle them, slow screen rendering and increase computational effort. Among these efforts, those based on the use of Light Detection and Ranging (LiDAR) pose the problem that interpolation techniques in commercially available GIS software packages (e.g., IDW, Spline, Kriging and TOPORASTER, among others) for developing DEMs from point elevations have difficulty processing large amounts of data. Terrain Dataset is an alternative format for storing topographic data that intelligently decimates data points and creates simplified, yet equally accurate for practical purposes, DEMs or Triangular Irregular Networks (TIN). This study uses terrain datasets to evaluate the impact that the thinning method (i.e., window size and z-value), pyramid level and the interpolation technique (linear or natural neighbor) used to create the DEMs have on the watersheds delineated from them. Two case studies were considered for assessing the effect of the different methods and techniques. One of them consisted of dendritic topography in Williamson Creek, Austin, Texas, and the other of deranged topography in Hillsborough County, Florida. The results were compared using three standardized error metrics that measure the accuracy of the watershed boundaries, and computational effort. For the Williamson creek (steeper terrain), point thinning during the terrain creation process or the interpolation method choice did not affect the watershed delineation; while, in the Hillsborough (flat terrain), the method for point thinning and interpolation techniques highly influenced the resulting watershed delineation.
Olivera, F.; Ferreira, C.; Djokic, D.
Creation of a Multiresolution and Multiaccuracy Dtm: Problems and Solutions for Heli-Dem Case Study
NASA Astrophysics Data System (ADS)
The work is part of "HELI-DEM" (HELvetia-Italy Digital Elevation Model) project, funded by the European Regional Development Fund within the Italy-Switzerland cooperation program. The aim of the project is the creation of a unique DTM for the alpine and subalpine area between Italy (Piedmont, Lombardy) and Switzerland (Ticino and Grisons Cantons); at present, different DTMs, that are in different reference frames and have been obtained with different technologies, accuracies, and resolutions, have been acquired. The final DTM should be correctly georeferenced and produced validating and integrating the data that are available for the project. DTMs are fundamental in hydrogeological studies, especially in alpine areas where hydrogeological risks may exist. Moreover, when an event, like for example a landslide, happens at the border between countries, a unique and integrated DTM which covers the interest area is useful to analyze the scenario. In this sense, HELI-DEM project is helpful. To perform analyses along the borders between countries, transnational geographic information is needed: a transnational DTM can be obtained by merging regional low resolution DTMs. Moreover high resolution local DTMs should be used where they are available. To be merged, low and high resolution DTMs should be in the same three dimensional reference frame, should not present biases and should be consistent in the overlapping areas. Cross-validation between the different DTMs is therefore needed. Two different problems should be solved: the merging of regional, partly overlapping low and medium resolution DTMs into a unique low/medium resolution DTM and the merging with other local high resolution/high accuracy height data. This paper discusses the preliminary processing of the data for the fusion of low and high resolution DTMs in a study-case area within the Lombardy region: Valtellina valley. In this region the Lombardy regional low resolution DTM is available, with a horizontal resolution of 20 meters; in addition a LiDAR DTM with a horizontal resolution of 1 meter, which covers only the main hydrographic basins, is also available. The two DTMs have been transformed into the same reference frame. The cross-validation of the two datasets has been performed comparing the low resolution DTM with the local high resolution DTM. Then, where significant differences are present, GPS survey have been used as external validation. The results are presented. Moreover, a possible strategy for the future fusion of the data, is shortly summarized at the end of the paper.
Biagi, L.; Carcano, L.; Lucchese, A.; Negretti, M.
Toward a simple, DEM-based model for linking channel morphology with Atlantic salmon habitat
NASA Astrophysics Data System (ADS)
Atlantic salmon require swiftwater gravel-bedded rivers for rearing and spawning. Morphology of the rivers in coastal New England and Atlantic Canada is strongly influenced by glacial and land-use history. Longitudinal profiles are characterized by relatively steep (gradient >0.002) and flat (gradient <0.0005) segments, with length scales of several km. This heterogeneity corresponds to strong variations in channel form (boulder cascades, pools and riffles, plane beds, low-gradient wetlands, mainstem lakes), substrate grain size, and aquatic habitat characteristics. We seek to develop methods to use simple GIS-based measurements to investigate relationships between channel processes and habitat characteristics. The near extirpation of Atlantic salmon from U.S. rivers motivates restoration efforts, including the removal of barriers to migration and instream habitat restoration projects. Resource managers desire GIS-based methods to facilitate rapid identification of potential spawning and rearing habitat within channel networks. We develop methods for predicting channel conditions using traditional (10-30 m pixels) and lidar (1-m pixels) digital elevation models (DEMs). We calibrate and test our methods using field surveys of habitat, channel form and bed grain size in coastal Maine and New Brunswick. A statistical approach uses stream gradient measured over segments defined by channel centerline intersections with contour lines (3-6 m intervals) on digitized topographic maps, contributing area, and physiographic province. This model explains 73% of the variation in field-identified rearing habitat. Commonly available GIS data allows this model to be applied over large areas, making it useful for regional habitat assessments. We present preliminary results from a process- based model that predicts bed grain size using morphologic measurements from lidar DEMs and the Shields equation. We compare these predictions to field grain size and habitat mapping. The lidar-based method has similar predictive capability to the statistical model, and greater spatial resolution (channel gradient is measured over 0.5-m vertical intervals). We suggest that failures in the lidar-based approach likely relate to local variations in channel roughness and sediment size and supply not included in the model. Further, we speculate that these mismatches may present an opportunity to prioritize stream restoration efforts such as removal of small dams or additions of large woody debris by identifying river reaches with potential high- quality habitat.
Snyder, N. P.; Wilkins, B. C.; Wright, J. R.
A Morpho-Neotectonic Map of western Taiwan Based on Fractal Analysis of DEM
NASA Astrophysics Data System (ADS)
The Taiwan orogenic belt is a curved range belt formed by late Cenozoic oblique convergence, indentation and rotation tectonics between the Eurasian plate and the Philippine Sea plate. This study applies the fractal analysis of DEM to help delineate morphotectonic features and compiles a morpho-neotectonic map of western Taiwan. This map gives a more detailed picture on the kinematics of oblique convergence and indentation tectonics, especially in the low hills and coastal plains. The angled variogram method was applied in a moving window fashion to extract the fractal vector from a 40-meter resolution DEM. The fractal vector can readily disclose anisotropic nature of a landscape surface which is known to be related to geologic structures. Morphotectonic features manifested by the fractal vector are are mainly distributed in the low hills and coastal plains over which Quarternary sediments cover. There are five morphotectonic domains divided in the frontal thrust belt and coastal plains of western Taiwan. The Changhua-Yenlin Domain (III) is bounded by the Changhua Fault to the north and the B Fault to the south. It is situated upon the Peikang indenting block and is essentially aseimic and gently folded. To the north, the Taichung-Miali Domain (II) is subjected to transpressional tectonics and characterized by oblique slip thrusts and left-lateral simple shear deformation. The Tuntzuchiao Fault of 1935 earthquake is a right-lateral antithetic shear to accommodate crustal deformation. To the south, the Chiayi Domain (IV) is subjected to transtensional tectonics and characterized by inferred strike-slip faults and right-lateral simple shear deformation. The associated north-south trending fold system had been mapped by. The east-west trending normal faults had been mapped by CPC. The Meishan Fault of 1906 earthquake and the Shinhua Fault of 1946 earthquake can be deemed as right-lateral synthetic shear in this simple shear model. In spite of the extensional Taipei Basin, the Hsinchu-Taipei Domain (I) in northern Taiwan is not only in contractional tectonics, but also in divergent strike-slip component and block rotation. Local occurrences of extension roughly parallel to the trend of major structures. In southern Taiwan, the Tainan-Kaohsiung Domain (V) is less affected by the Peikang Indenting Block, yet the SW escape tectonics still plays some role. This Domain is characterized by northeast trending folds and thrusts with dextral slip component. Both synthetic and antithetic shears are also recognized in this Domain. Based upon the contrasting pattern of the fractal vector and the seismic distribution, the morpho-neotectonic map may also provide a criteria to evaluate the relative tectonic activity of the five Domains in western Taiwan.
Sung, Q.; Chen, Y.; Lu, C.; Lee, C.
The Multi-Instrument, Comprehensive Differential Emission Measure (DEM) of the Solar Corona During Flares and Quiescent Periods
NASA Astrophysics Data System (ADS)
Thermal plasma in the solar corona, while often modeled as isothermal for ease of analysis, is in fact decidedly multi-thermal, ranging from ~1-2 MK in the quiescent corona to ~30-50 MK in intensely flaring loops. It has proven difficult to obtain a well-constrained differential emission measure (DEM) from a single instrument, as the wavelength ranges of individual instruments, even those with broadband coverage, provide sensitivity to only a limited range of plasma temperatures. Recently, we developed a new technique using combined extreme ultraviolet (EUV) and soft and hard X-ray (SXR, HXR) data from the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), respectively, to obtain a self-consistent DEM that is strongly constrained across the full range of coronal plasma temperatures (<2 to >50 MK). An accurate, precise determination of the plasma temperature distribution enables not only studies of plasma heating and thermal plasma evolution, but can also provide strong constraints on the non-thermal accelerated electron population, including the low-energy cutoff which is typically determined only as a loose upper limit.We present EVE+RHESSI DEM results from selected intense (X-class) flares from solar cycle 24, including determining the non-thermal low-energy cutoff and examining how this evolves with the temperature distribution. We also apply this technique to combine EUV data from EVE with SXR data from the GOES X-ray Sensor (XRS) and the X123, a new SXR spectrometer flown on two recent SDO/EVE calibration sounding rockets, to examine the DEM during quiescent (non-flaring) times with varying activity levels; the X-ray data provide crucial constraints on the high-temperate extent of the DEM and any potential non-thermal emission. We compare these results with those from a parallel technique to derive DEMs from imaging data from the Atmospheric Imaging Assembly (AIA) onboard SDO, and we discuss the implications for plasma heating, both during flares and in the quiescent corona. This research is supported by NASA contracts NAS5-98033 and NAS5-02140, and NASA Heliophysics Guest Investigator Grant NNX12AH48G.
Caspi, Amir; McTiernan, James; Warren, Harry; Woods, Thomas N.
Electrically-enhanced deposition of fine particles on a fiber: A numerical study using DEM
NASA Astrophysics Data System (ADS)
The deposition of small particles, charged or polarized, on a fiber embedded in a coupled field of electrostatics and viscous flow, has received renewed attention due to the technological needs of PM2.5 capture as well as the challenges of unresolved fundamental physics. In this paper, we introduce a general computational method for this complex particle-electric-flow interactions, in which a boundary-element method (BEM) for the electrostatic field induced by the macroscopic fiber, an optimized multiple expansion method for the long-range electrostatic field induced by the particles, and a Discrete Element Method (DEM) that accounts for electrostatic, fluid and adhesive contact forces on particles are combined for the 3D simulation. The deposition mechanisms of charged and polarized particles on the fiber are investigated using the combined approach. First, it is found that the pre-polarization of fine particles dramatically enhances the deposition rate even by nearly an order of magnitude. Second, the effect of particle charge on the deposition is two-fold. The attractive particle-fiber interaction increases the initial deposition rate, and affects the further filtration process because of particle loading effect in this initial stage. The particle-particle repulsion always inhibits the deposition. Third, the charged particles tend to form new small dendrites rather than deposit on existing dendrites, causing the dendrite number larger than that in the cases of polarized or neutral particles.
Yang, Mengmeng; Li, Shuiqing; Liu, Guanqing; Yao, Qiang
Discrete element method (DEM) simulations of stratified sampling during solid dosage form manufacturing.
Discrete element model (DEM) simulations of the discharge of powders from hoppers under gravity were analyzed to provide estimates of dosage form content uniformity during the manufacture of solid dosage forms (tablets and capsules). For a system that exhibits moderate segregation the effects of sample size, number, and location within the batch were determined. The various sampling approaches were compared to current best-practices for sampling described in the Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) guidelines. Sampling uniformly across the discharge process gave the most accurate results with respect to identifying segregation trends. Sigmoidal sampling (as recommended in the PQRI BUWG guidelines) tended to overestimate potential segregation issues, whereas truncated sampling (common in industrial practice) tended to underestimate them. The size of the sample had a major effect on the absolute potency RSD. The number of sampling locations (10 vs. 20) had very little effect on the trends in the data, and the number of samples analyzed at each location (1 vs. 3 vs. 7) had only a small effect for the sampling conditions examined. The results of this work provide greater understanding of the effect of different sampling approaches on the measured content uniformity of real dosage forms, and can help to guide the choice of appropriate sampling protocols. PMID:21635943
Hancock, Bruno C; Ketterhagen, William R
MFIX-DEM simulations of change of volumetric flow in fluidized beds due to chemical reactions
This study attempts to investigate the effect of gas volume change caused by chemical reactions on the flow hydrodynamics in a fluidized bed reactor. Various 2D simulations of ozone decomposition and the reverse reaction are conducted with a EulerianñLagrangian code-MFIX-DEM for a small-scale bubbling fluidized bed. The effect of particle size is studied by simulating two types of bed material with different sizes. Both transient and time-averaged flow behaviors are analyzed. The influences of gas volume change due to chemical reactions are studied with respect to bed expansion, superficial gas velocity, bubble characteristics including bubble size and frequency. The fluidized bed is then divided into bubble, shell and emulsion phases to further analyze the behavior of emulsion phase and gas flow distribution in different phases. A profound impact on the flow hydrodynamics by the gas volume change is found. For the small systems studied, the volume change in gas flow demonstrates the most significant influence on the gas flow in the shell phase for coarse particles and the bubble phase for fine particles.
Li, Tingwen; Guenther, Chris
Macromolecular Structure Modeling from 3DEM Using VolRover 2.01
We report several tools for 3DEM structure identification and model-based refinement developed by our research group and implemented in our in-house software package, VolRover. For viral density maps with icosahedral symmetry, we segment the capsid, polymeric and monomeric subunits using segmentation techniques based on symmetry detection and fast marching. For large biomolecules without symmetry information, we use a multi-seeded fast-marching method to segment meaningful substructures. In either case, we subject the resulting segmented subunit to secondary structure detection when the EM resolution is sufficiently high, and rigid-body fitting when the corresponding crystal structure is available. Secondary structure elements are identified by our volume- and boundary-based skeletonization methods as well as a new method, currently in development, based on solving the grassfire flow equation. For rigid-body fitting, we use a translational fast Fourier based scheme. We apply our segmentation, secondary structure elements identification, and rigid-body fitting techniques to the PSB 2011 cryo-EM modeling challenge data, and compare our results to those submitted from other research groups. The comparisons show that our software is capable of segmenting relatively accurate subunits from a viral or protein assembly, and that the high segmentation quality leads in turn to high-quality results of secondary structure elements identification and rigid-body fitting.
Zhang, Qin; Bettadapura, Radhakrishna
Classification of topography using DEM data and its correlation with the geology of Greece
NASA Astrophysics Data System (ADS)
Continuous topography from Digital Elevation Model (DEM) data is frequently segmented into terrain classes based on local morphological characteristics of terrain elevation, e.g., local slope gradient and convexity. The resulting classes are often used as proxies for the average shear wave velocity up to 30 m, and the determination of ground types as required by the Eurocode (EC8) for computing elastic design spectra. In this work, we investigate the links between terrain related variables, particularly slope gradient, extracted for the area of Greece from the Shuttle Radar Topography Mission (SRTM) 30 arc second global topographic data available from the United States Geological Survey (USGS), with: (a) the global terrain classification product of Iwahashi and Pike (2007) in which 16 terrain types are identified for the same spatial resolution, and (b) information on geological units extracted at the same resolution from the geological map of Greece at a scale of 1/500000 as published from the Institute of Geology and Mineral Exploration (IGME). An interpretation of these links is presented within the context of understanding the reliability of using geology, slope and terrain classes for site characterizations of earthquake risk in a high seismicity area like Greece. Our results indicate that slope is a somewhat biased proxy for solid rocks, whereas in Alluvial deposits the distance to and type of the nearest geological formation appears to provide qualitative information on the size of the sedimentary deposit.
Zargli, Eleni; Liodakis, Stelios; Kyriakidis, Phaedon; Savvaidis, Alexandros
Fast glacier volume change detection based on least squares 3D surface matching of DEM
NASA Astrophysics Data System (ADS)
In this paper, a new fast detection method on glacier volume changing has been adopted and analyzed to solve shortages of low precision and inefficiency in traditional algorithms. High-precision Digital Elevation Model (DEM) has been used in this method to improve the accuracy of the result. Besides, GCPs are unnecessary in this new method so that it can be widely applied in glacier districts where GCPs are hard to be set. Furthermore, Least squares 3D surface matching method has also been improved in this paper in that blocking computing has been added to strengthen the speed and accuracy of this method. Multitemporal images in Xinjiang Province, china have been used to test the accuracy and efficiency of this proposal method: iterations are 12 and D-values are small. The test results show that this method has the advantages of Least squares 3D surface matching so that it can be widely used to satisfy the speed and accuracy of fast changing detection of Glacier Volume.
Fu, Sitao; Li, Zhen; Tian, Bangsen; Zhao, Liangbo; Tang, Zhihua
Production of Optimized DEM Using IDW Interpolation Method (Case Study; Jam and Riz Basin-Assaloyeh)
NASA Astrophysics Data System (ADS)
In this research, preparing the optimized Digital Elevation Model (DEM)of Jam and Riz basin was studied by use of Inverse Distance Weighting (IDW) and utilization of GIS technique. Performing of IDW method depends on several factors including cell size, number of neighbor`s points, point searching radius and optimized power. On this basis, two Geostatistical methods were used for determination of points searching radius of standard ellipse and standard deviation ellipse. Considering the fixed cell size in network with value of 3 which represents weighting degree of points and with determining the rotation angle and measure of axis of standard deviation ellipse and calculation of optimized radius in standard ellipse by use of statistical method, then optimized power was automatically derived in ArcGIS 9.2 environment. In this method the number of neighbor's points was selected with four repetition points of 3, 5, 7 and 15. However, 8 digital elevation models were gained after the mentioned processes. Finally, digital elevation models of 1 to 8 were compared with control points using compare means test in SPSS11.5 statistical software which shown the IDW-3 with the best conditions recommended as the optimized model. Although the results are showing a similar forms but from them IDW3 model has the lowest mean standard error of 0.26842 which is used seven neighbor points.
Soleimani, K.; Modallaldoust, S.
Quantifying Ice-sheet/Ice-shelf Dynamics and Variability with Meter-scale DEM and Velocity Timeseries
NASA Astrophysics Data System (ADS)
Both the Antarctic and Greenland ice sheets are losing mass at an increasing rate, although loss due to accelerating flow and dynamic thinning remains poorly understood. We are using complementary data from repeat satellite and airborne observations to investigate the relationship between ice-sheet/ice-shelf dynamics and geometry on seasonal to interannual timescales. High-resolution along-track stereo imagery from commercial satellite vendors DigitalGlobe and GeoEye provides unprecedented spatial (~0.5 m/px with ~17 km swath width) and temporal (weekly/monthly) resolution for these efforts. We have developed an automated pipeline using open-source software to produce orthoimage, DEM, and surface velocity products from DigitalGlobe imagery. High-contrast surface texture (e.g. sastrugi, crevasses) visible at sub-meter resolution provides near-perfect image correlation (~99% success rate) during DEM and velocity map derivation. Elevation data from IceBridge ATM/LVIS, ICESat GLAS, and GPS campaigns are used to correct DEMs and perform accuracy assessment. Preliminary tests over exposed bedrock provide relative vertical accuracy estimates of <1-2 m for Worldview-1/2 DEMs. Velocity data from TerraSAR-X and GPS campaigns provide validation for surface velocity products, with horizontal error estimates of <10 m. Velocity and elevation change products with 2-4 m/px spatial resolution allow for unprecedented 3D dynamic characterization of sub-km flow transition zones (e.g. grounding lines, shear margins), capturing both local and regional variations due to melting and dynamic thinning. We present timeseries for West Greenland (Jakobshavn front - 20 observations, Jakobshavn south catchment - 10) and West Antarctica (Pine Island and Thwaites - 5 each) from 2009-2012. These observations complement ongoing efforts to measure and model outlet glacier dynamics, with implications for future ice-sheet mass balance estimates.
Shean, D. E.; Joughin, I. R.; Smith, B. E.; Moratto, Z. M.; Porter, C.; Morin, P. J.
The Wind of the B[e] Supergiant Henize S22 Viewed through a Reflection Nebula in DEM L106
Narrowband HST WFPC2 images reveal a bow-shock-like halo around the H II region N30B toward the B[e] supergiant Hen S22 located within the larger DEM L106 nebula in the Large Magellanic Cloud. High-dispersion spectra of N30B show a narrow Halpha emission component from the ionized gas; the velocity variations indicate a gas flow of -5 to -10 km s-1 in
You-Hua Chu; C.-H. Rosie Chen; Charles Danforth; Bryan C. Dunne; Robert A. Gruendl; YaÎl NazÈ; M. S. Oey
An Example of Realistic Modelling of Rock Dynamics Problems: FEM/DEM Simulation of Dynamic Brazilian Test on Barre Granite
NASA Astrophysics Data System (ADS)
The scope of this study is to numerically simulate the behaviour of Brazilian disc specimens as observed in laboratory during dynamic, high-strain rate, indirect tensile tests using an innovative combined finite-discrete element method (FEM/DEM) research code. Laboratory experiments using a split Hopkinson pressure bar (SHPB) apparatus were conducted by the authors and the measured indirect tensile strength values were used to verify the FEM/DEM models. In the models the applied boundary conditions, related to the loading rate of the specimen, were matched with the experimental observations. The results of the numerical simulations, including tensile strength and failure time, are in agreement with the laboratory findings. The main failure mechanisms, i.e. tensile splitting along loading axis and shear failure close to loading platens are captured by the numerical model. A linear relationship between tensile strength and loading rate is found for the range of dynamic strain rates tested and simulated. The simulation results are in good agreement with laboratory observations and demonstrate the potential for using FEM/DEM to realistically model dynamic response of rocks.
Mahabadi, O. K.; Cottrell, B. E.; Grasselli, G.
Das Image deutscher ÷ko-Zeichen - Unterscheiden Verbraucher zwischen ÷ko-Verbandszeichen, ÷ko- Herstellermarken, ÷ko-Handelsmarken und dem BioSiegel? - The Image of Organic Labels - Do Consumers Differentiate between Labels of Organic Producer Organisations, Organic Brands, Retailers' Own Organic Labels and the 'Bio Siegel'?
In Germany, consumers are confronted with more than 100 organic labels, which lead to uncertainty about the reliability of such labels. As a solution, one public organic label, the Bio-Siegel, was designed. This raises two questions from the marketing perspective: (1) Do any of the individual organic labels have a specific image, a unique selling proposition (USP)? (2) Does the
A. Wirthgen
Volcanic geomorphology and tectonics of the Aeolian archipelago (Southern Italy) based on integrated DEM data
NASA Astrophysics Data System (ADS)
The geomorphological and morphometric analysis of the sea floor topography surrounding the Aeolian Islands, South Tyrrhenian Sea, Italy, provides insights into the relationships between the volcanological evolution of the islands and their tectonic features. We constructed geomorphological maps of the submarine portions of the seven large edifices constituting the islands on the basis of a DEM with a 5 m resolution step. These maps include constructional and destructional landforms such as submarine volcanic vents located west of Lipari and north of Alicudi, and hummocky surfaces recognised north of Lipari and Salina. The latter landforms, together with the occurrence of large scars affecting the main edifices on land, suggest that sector collapses affected some islands. Geomorphological data indicate that the location of subaerial and submarine vents is strongly controlled by local tectonic structures striking WNW-ESE (Alicudi-Filicudi sector), NNW-SSE (Salina-Lipari-Vulcano sector) and NE-SW (Panarea-Stromboli sector). The islands can be divided into two groups on the basis of some morphometric parameters: a first group with a pancake-like shape, Dp/D (abrasion platform diameter/basal diameter) higher than 0.40 and H/D (total height/basal diameter) lower than 0.13, and a second group with a conical shape, characterised by Dp/D lower than 0.34 and H/D higher than 0.14. These ratios and other morphometric parameters reflect the different volcanological and structural evolution of the Aeolian Islands. The pancake-like shaped complexes have been created, in addition to their submarine stage, by extrusive and highly explosive activity, whereas the cone-shaped edifices have been characterised by effusive or moderate explosive activity.
Favallim, Massimiliano; Kar·tson, D·vid; Mazzuoli, Roberto; Pareschi, Maria Teresa; Ventura, Guido
A stochastic framework for estimating changes in storage from repeat DEMs
NASA Astrophysics Data System (ADS)
Many strategies for quantifying uncertainty in estimates of geomorphic change involve establishing a threshold, or minimum level of detection (minLoD), below which any topographic changes are discarded from the analysis. The general premise is that when there is a greater difference between two topographic surfaces one has greater confidence that the change observed reflects real geomorphic change, and is not just an artifact of survey techniques or grid interpolation. However, approaches that establish binary change detection thresholds can be problematic in landscapes where much of the topographic change is subtle, as is the case in many fluvial environments. Additionally, a necessary assumption of strategies that rely on establishing a minLoD is that erosion and deposition are normally distributed. Yet, deposition in rivers is often more diffuse than erosion, thus a relatively greater proportion of the total deposition may be excluded from the analysis. Here, we present an alternative approach for estimating change in storage volumes in light of quantified uncertainty estimates. Our strategy relies on a stochastic modeling framework to generate probability distribution functions of erosion and deposition for each cell in a DEM of difference. We demonstrate an application of our technique using a multi-year data set from a restored reach of the Provo River in northern Utah. We illustrate the advantages this technique provides in a setting where the topographic changes of interest are relatively subtle and accurately identifying these changes has significant management implications. Additionally, we demonstrate how the probabilistic approach provides a framework for more fully describing channel morphodynamics and may improve insights gained from morphologic sediment budgets.
Erwin, S. O.; Wilcock, P.; Wheaton, J. M.; Schmidt, J. C.
Integration of SRTM DEM and Hydraulic Analysis for Flood Response Planning.
NASA Astrophysics Data System (ADS)
The ability to delineate potential flood inundation areas is one of the most important requirements for flood response planning. Historical hydrologic records and high-resolution topographic data are essential to model flood inundation and to map areas at risk of inundation. For Afghanistan, historical hydrologic data enable the analysis of flood frequency, but the accurate delineation of flood inundation zones is limited by the lack of high- resolution elevation data. This study has developed a method for coupling hydraulic analysis and Geographic Information System (GIS) technology to delineate flood risk maps of the Helmand and Kabul drainage basins in Afghanistan. Land surface elevation data from the Shuttle Radar Topography Mission (SRTM) were used to create an area-elevation profile with respect to the rivers that flow into these two basins. Using the profile, we computed cross-sectional area and wetted perimeter for each 1-m increment in elevation. Manning's equation was applied to compute river discharge for each 1-m increment in water level using cross-sectional area, wetted perimeter and slope of the respective river reach. Results for the gauged river reaches were compared with 25, 50, and 100-year return period floods based on a flood frequency from the historical stream flow data, and associated depths of water were estimated for each return period flood. Peak flows at gauge stations were extrapolated to ungauged river reaches based on upstream drainage area. The estimated depths of water for each river reach were used as thresholds to identify areas subject to flood inundation, using the SRTM Digital Elevation Model (DEM) with respect to the rivers. The resulting flood inundation polygons were combined in a GIS with roads, infrastructure, settlements, and higher resolution satellite imagery to identify potential hazards due to flooding, and provide detailed information for flood response planning.
Pervez, M.; Asante, K. O.; Smith, J. L.; Verdin, J. P.; Rowland, J.
DEM-based model for reconstructing volcano's morphology from primary volcanic landforms
NASA Astrophysics Data System (ADS)
Volumes of magma intruded in and emitted by volcanoes through time can be estimated by reconstruction of volcano's morphology and time sequence. Classical approaches for quantifying magma volumes on active volcanoes are based on the difference between pre- and post-eruption digital elevation models (DEM), but this kind of approach needs the pre-eruptive surfaces to be available. For old and eroded volcanoes these surfaces are poorly constrained. However, because the geometrical form of many volcanic edifices exhibits a remarkable symmetry we propose, here, a new approach using primary volcanic landforms in order to estimate the amount of the both erupted and eroded material and to locate eruptive centers. A large fraction of composite volcanoes have near constant slope on their flanks and a form that is concave upwards near their summits. But many phenomena can lead to non-symetrical edifices and complex morphologies can result, for example from parasitic centers of volcanism on the flanks, from alternation of short effusive and explosive construction phases, from flank or caldera collapses, or from glacial and other types of erosion. In this study we propose that, on the first order approximation, complex morphologies can be modeled by piling regular cones. In this model, cones centers and slopes are derived by fitting primary volcanic landform with a linear function :elevation=f(distance from center). Such an approach allows to estimate both errors on location of the eruptive center and on the volume of the resulting cones. This model can then be used for quantifying volume of erupted and eroded material, and for quantifying catastrophic events as giant landslides or flank collapse. This approach is tested on four different active volcanoes : Mount Mayon (Philippines), Mount Fuji (Japan), Mount Etna (Sicily) and Mount Teide (Canary Island) to estimate errors in volume between modeled and actual edifices. It is then used on volcanoes of La RÈunion hotspot to reconstruct the Piton des Neiges and Piton de la Fournaise volcanoes at its different stages of growing.
Gayer, Eric; Lopez, Philippe; Michon, Laurent
Looking Through the Ice: Searching for Past and Present Habitable Zones in the Martian North Polar Region Using MOLA DEMs
NASA Astrophysics Data System (ADS)
Hydrothermal systems have been acknowledged as important gateways to accessing a potential subsurface biology (extant or extinct) on Mars. Groundwater circulation, sustained for up to one billion years by large plutonic bodies (as modeled by previous authors), might well be capable of tapping into a deep subsurface biosphere and subsequently carrying members of microbial communities to the surface. Hence, future robotic missions with near surface drilling capabilities may be able to unearth cryopreserved biosignatures, or perhaps extant organisms, in the midst of the hydrothermal system itself. Digital Elevation Models (DEMs) constructed from Mars Orbiter Laser Altimeter (MOLA) data have proved to be a valuable tool in the search for potential habitable zones for extant and extinct life, and the detection of possible hydrothermal systems on Mars. When formatted for use in a Geographical Information Systems (GIS) software package such as ESRI's ArcView, MOLA data can be used to compose DEMs. Those DEMs can, in turn, be used to create contour maps, to allow profiling through features of interest, and to generate hillshaded views, which provide an image-like perspective of a selected area. Furthermore, DEMs eliminate many problems associated with photographic images such as over-/underexposure, poor focus, and albedo values too high or low for optimal observations. During this study, DEMs were used in the analysis of several regions north of 70∞ N latitude, in the Martian north polar cap and polar cap margin. The regions were selected during a Viking image survey that concentrated on the location of surface expressions of potential magma-ice interactions, and hence past or present hydrothermal activity. Specific features sought included individual volcanoes and volcanic fields, as well as pseudocrater fields, subglacial volcanic constructs (such as tuyas and tindar ridges), fluvial channels and outwash plains (indicative of jîkulhlaup flooding events), possible subglacial lakes, and impact melt sheets capable of generating and sustaining localized hydrothermal systems. Two candidate sites, both located in the Olympia Planitia region in the remnant margin of the Martian north polar cap, will be discussed. MOLA revealed potential fluvial and volcanic activity beneath the ice of one site, and a possible mix of small volcanoes and rootless pseudocraters in the other region. Hence, those two auspicious sites, significant for astrobiologically driven research, represent a diversity of possible hydrothermal regions. It must be cautioned at all times that interpretations made of the selected sites are done so through polar ice. Nevertheless, the wealth of information imparted by MOLA of the underlying terrain is remarkable. Although MOLA is incapable of revealing present aqueous processes beneath the ice surface, it is an invaluable aid in the location of promising subglacial sites that suggest a history of hydrothermal activity.
Payne, M. C.; Farmer, J. D.
Relationship between glomerular lesions, serum creatinine and interstitial volume in membrano-proliferative glomerulonephritis
Zusammenfassung An 33 Patienten mit membranoproliferativer GN verschiedener Schweregrade konnte gezeigt werden, daþ keine sicheren Beziehungen zwischen Ausmaþ der glomerul‰ren Ver‰nderungen und dem Serum-Kreatininspiegel bestehen.
H. Fischbach; S. Mackensen; K.-E. Grund; A. Kellner; A. Bohle
Release of a 10-m-resolution DEM for the whole Italian territory: a new, freely available resource for research purposes
NASA Astrophysics Data System (ADS)
Digital elevation models (DEMs) are fundamental in any kind of environmental or morphological study. DEMs are obtained from a variety of sources and generated in several ways. Nowadays, a few global-coverage elevation datasets are available for free (e.g., SRTM, http://www.jpl.nasa.gov/srtm; ASTER, http://asterweb.jpl.nasa.gov/). When the matrix of a DEM is used also for computational purposes, the choice of the elevation dataset which better suits the target of the study is crucial. Recently, the increasing use of DEM-based numerical simulation tools (e.g. for gravity driven mass flows), would largely benefit from the use of a higher resolution/higher accuracy topography than those available at planetary scale. Similar elevation datasets are neither easily nor freely available for all countries worldwide. Here we introduce a new web resource which made available for free (for research purposes only) a 10 m-resolution DEM for the whole Italian territory. The creation of this elevation dataset was presented by Tarquini et al. (2007). This DEM was obtained in triangular irregular network (TIN) format starting from heterogeneous vector datasets, mostly consisting in elevation contour lines and elevation points derived from several sources. The input vector database was carefully cleaned up to obtain an improved seamless TIN refined by using the DEST algorithm, thus improving the Delaunay tessellation. The whole TINITALY/01 DEM was converted in grid format (10-m cell size) according to a tiled structure composed of 193, 50-km side square elements. The grid database consists of more than 3 billions of cells and occupies almost 12 GB of disk memory. A web-GIS has been created (http://tinitaly.pi.ingv.it/ ) where a seamless layer of images in full resolution (10 m) obtained from the whole DEM (both in color-shaded and anaglyph mode) is open for browsing. Accredited navigators are allowed to download the elevation dataset.
Tarquini, S.; Nannipieri, L.; Favalli, M.; Fornaciai, A.; Vinci, S.; Doumaz, F.
The influence of accuracy, grid size, and interpolation method on the hydrological analysis of LiDAR derived dems: Seneca Nation of Indians, Irving NY
NASA Astrophysics Data System (ADS)
Light Detection and Ranging (LiDAR) derived Digital Elevation Models (DEMs) provide accurate, high resolution digital surfaces for precise topographic analysis. The following study investigates the accuracy of LiDAR derived DEMs by calculating the Root Mean Square Error (RMSE) of multiple interpolation methods with grid cells ranging from 0.5 to 10-meters. A raster cell with smaller dimensions will drastically increase the amount of detail represented in the DEM by increasing the number of elevation values across the study area. Increased horizontal resolutions have raised the accuracy of the interpolated surfaces and the contours generated from the digitized landscapes. As the raster grid cells decrease in size, the level of detail of hydrological processes will significantly improve compared to coarser resolutions including the publicly available National Elevation Datasets (NEDs). Utilizing a LiDAR derived DEM with the lowest RMSE as the 'ground truth', watershed boundaries were delineated for a sub-basin of the Clear Creek Watershed within the territory of the Seneca Nation of Indians located in Southern Erie County, NY. An investigation of the watershed area and boundary location revealed considerable differences comparing the results of applying different interpretation methods on DEM datasets of different horizontal resolutions. Stream networks coupled with watersheds were used to calculate peak flow values for the 10-meter NEDs and LiDAR derived DEMs.
Clarkson, Brian W.
New insights from DEM's into form, process and causality in Distributive Fluvial Systems
NASA Astrophysics Data System (ADS)
Recent developments in platforms and sensors, as well as advances in our ability to access these rich data sources in near real time presents geoscientists with both opportunities and problems. We currently record raster and point cloud data about the physical world at unprecedented rates with extremely high spatial and spectral resolution. Yet the ability to extract scientifically useful knowledge from such immense data sets has lagged considerably. The interrelated fields of database creation, data mining and modern geostatistics all focus on such interdisciplinary data analysis problems. In recent years these fields have made great advances in analyzing the complex real-world data such as that captured in Digital Elevation Models (DEM's) and satellite imagery and by LIDAR and other geospatially referenced data sets. However, even considering the vast increase in the use of these data sets in the past decade these methods have enjoyed only a relatively modest penetration into the geosciences when compared to data analysis in other scientific disciplines. In part, a great deal of the current research weakness is due to the lack of a unifying conceptual approach and the failure to appreciate the value of highly structured and synthesized compilations of data, organized in user-friendly formats. We report on the application of these new technologies and database approaches to global scale parameterization of Distributive Fluvial Systems (DFS) within continental sedimentary basins and illustrate the value of well-constructed databases and tool-rich analysis environments for understanding form, process and causality in these systems. We analyzed the characteristics of aggradational fluvial systems in more than 700 modern continental sedimentary basins and the links between DFS within these systems and their contributing drainage basins. Our studies show that in sedimentary basins, distributive fluvial and alluvial systems dominate the depositional environment. Consequently, we have found that studies of modern tributary drainage systems in degradational settings are likely insufficient for understanding the geomorphology expressed within these basins and ultimately for understanding the basin-scale architecture of dominantly distributive fluvial deposits preserved in the rock record.
Scuderi, Louis; Weissmann, Gary; Hartley, Adrian; Kindilien, Peter
GIS modelling of earthquake damage zones using satellite remote sensing and DEM data
NASA Astrophysics Data System (ADS)
The devastating earthquake that occurred in Wenchuan County, Sichuan Province, China, on the 12th May 2008, caused widespread damage and devastation to rural communities and economy. The terrain of the entire region has been weakened and is now highly susceptible to long-term slope instability that will trouble this region for many years to come. Before the earthquake, the maximum seismic intensity expected in the region was VI-VIII in the 12-degree Liedu scale (the intensity measure adopted in China). However, the actual intensity caused by the earthquake ranged between VIII and XI. The seismic intensity map is practical for regional guidance but lacks the detail to provide an adequate representation of the true damage level, in terms of current status and future potential in such a seismically active and populated region, especially when the hazards and risks are likely to be multiple and cascading in high relief areas. This paper presents a GIS based novel approach to earthquake damage zone modelling using satellite remote sensing and DEM data. The novelty is to take into account the co-seismic ground deformation (measured using differential SAR interferometry) as an important modulating factor in modelling the susceptibility of earthquake related geohazards, together with conventional multi-criteria factors which draw on geological and topographical variables such as rock competence, slope, proximity to drainage, and fracture density. The modulating effect of the earthquake greatly enhances the susceptibility in the areas where the majority of the ensuing landslides and debris-flows actually took place. When this susceptibility model is further modulated by the mapped surface disruption caused by the earthquake (which encompasses all forms of mass movement and urban destruction), it is directly linked to seismic intensity and we call it " earthquake damage". The output earthquake damage map represents both the current damage status as well as the future damage (hazard) potential. The resulting earthquake damage map for the Beichuan region clearly defines a series of zones of increasing seismic intensity, approximately corresponding to Liedu values VIII-XI but with great details.
Liu, Jian Guo; Mason, Philippa J.; Yu, Eric; Wu, Meng-Che; Tang, Chuan; Huang, Runqiu; Liu, Hanhu
2D Distinct Element Method (DEM) models of the initiation, propagation and saturation of rock joints
NASA Astrophysics Data System (ADS)
In layered sequences, rock joints usually best develop within the more brittle layers and commonly display a regular spacing that scales with layer thickness. A variety of conceptual and mechanical models have been developed for these observations. A limitation of previous approaches, however, is that fracture initiation and associated interface slip are not explicitly simulated; instead, fractures were predefined and interfaces were welded. To surmount this problem, we have modelled the formation and growth of joints in layered sequences by using the two-dimensional Distinct Element Method (DEM) as implemented in the Particle Flow Code (PFC-2D). In PFC-2D, rock is represented by an assemblage of circular particles that are bonded at particle-particle contacts. Failure occurs if either the tensile or shear strength of a bond is exceeded. The models comprise a central brittle layer with high Youngís modulus, which is embedded in a low Youngís modulus matrix. The interfaces between the layers are defined by ësmooth jointí contacts, a modelling feature that eliminates interparticle bumpiness and associated interlocking friction. Consequently, this feature allows the user to assign macroscopic properties such as friction and cohesion along layer interfaces in a controlled manner. Layer parallel extension is applied by assigning a velocity to particles at the lateral boundaries of the model while maintaining a constant vertical confining pressure. Models were extended until joint saturation in the central layer was reached. We thereby explored the impact of confining pressure and interface properties (friction, cohesion) on joint spacing. A number of important conclusions can be drawn from our models: (i) The distributions of average horizontal normal stress within the layer and of shear stress at the interface are consistent with analytical solutions (stress-transfer theory). (ii) At low interfacial shear strength, new joints form preferentially midway between two existing joints, whereas at high interfacial shear strength, new joints form both in the middle and at the sides of fracture bound blocks. (iii) Fractures predominantly initiate and propagate from interfaces. (iv) Joint spacing decreases as confining pressure, interface friction and cohesion are increased. (v) The spacing to thickness ratio at fracture saturation can be greater than one if interface slip is allowed.
Arslan, A.; Schˆpfer, M. P.; Walsh, J. J.; Childs, C.
Airborne LiDAR DEMs as a tool for deriving information on past glacier extent and ice flow
NASA Astrophysics Data System (ADS)
The quantification of ice volumes and the identification of ice flow regimes within historical glacier systems are important steps towards understanding historical phases of glacier advance and disintegration in the context of Holocene climate fluctuation. Topographic LiDAR DEMs provide an excellent tool for gaining various kinds of spatially distributed information. Several case studies have been performed in the Austrian Alps, where LiDAR DEMs are available for almost the entire glacier area. LiDAR DEMs achieve vertical accuracies of few decimetres and can be used to calculate hillshade images with flat incidence angles, so that the surface structures of moraines and other glacial deposits can be identified. These hillshade images were used together with aerial photographs to identify the LIA (Little Ice Age) moraines and the elevation of the lateral moraines, so that, together with information on today's ice volume, a lower limit for the LIA ice volume could be calculated. The resulting LIA glacier areas showed good coincidence with former reconstructions based on field mapping and airborne photogrammetry. In addition to that, historical ice flow directions could be derived from the structure of basal moraines. These data allow an interpretation of the changing contribution of specific tributary glaciers to a joint glacier tongue, which may result in an important switch in ice dynamics leading to fast glacier advances recorded by frontal moraines. The combination of terrestrial long-term observations and LiDAR data documents the genesis of specific geomorphological features in the periglacial area by recording the processes occurring during the disintegration of glacier tongues. For example, the deposition of the material from former medial moraines in the newly formed periglacial area can be identified and quantified from the LiDAR data as well as debris flows or rock falls from the LIA moraines.
Seiser, Bernd; Fischer, Andrea
Dem Assessment Derived from Close Range Photogrammetry: a Case Study from Kadavur Area, Karur District, Tamil Nadu, India
NASA Astrophysics Data System (ADS)
Close-Range Photogrammetry is an accurate, cost effective technique of collecting measurements of real world objects and conditions, directly from photographs. Photogrammetry utilizes digital images to obtain accurate measurements and geometric data of the object or area of interest, in order to provide spatial information for Engineering design, spatial surveys or 3D modeling. The benefits of close-range Photogrammetry over other field procedures are purported to be: Increased accuracy; complete as-built information; reduced costs; reduced on-site time; and effective for small and large projects. The same basic principle of traditional Aerial Photogrammetry can be applied to stereoscopic pictures taken from lower altitudes or from the ground. Terrestrial, ground-based, and close-range are all descriptive terms that refer to photos taken with an object-to-camera distance less than 300m (1000 feet). (Matthews, N.A, 2008). Close range Photogrammetry is a technique for obtaining the geometric information (e.g. position, distance, size and shape) of any object in 3D space that was imaged on the two dimensional (2D) photos, (Wolf, P.R, et.al, 2000) DEM Generation requires many processing and computation, such as camera calibration, stereo matching, editing, and interpolation. All the mentioned steps contribute to the quality of DEM. Image on close range Photogrammetry can be captured using three kind of camera: metric camera, semi-metric camera, and non-metric camera (Hanke, K., et.al, 2002). In this paper DEM quality assessed at Kadavur area, Karur district, Tamil Naudu, India using Close Range Photogrammetry technique, Commercial Digital Camera and Leica Photogrammetry Suite.
Anbarasan, S.; Sakthivel, R.
Extracting Precise and Affordable Dems Despite of the Clouds. Ajax: the Joining of Radar and Optical Strengths
NASA Astrophysics Data System (ADS)
On the one hand, onboard SPOT 5, the HRS instrument systematically collects stereopairs around the Globe since 2002. Each stereopair can encompass an area up to 600 km x 120 km within a single pass (i.e. 72 000 km≤ stereoscopic strips). Covering now more than 120 millions sq.km of the Earth landmasses, SPOT 5 stereoscopic imagery has become one of main satellite data sources for accurate DEM extraction, at least where the cloud coverage leaves a chance to do so ! On the other hand, the TerraSAR-X satellite, launched in June 2007, is able to collect radar data through the clouds in several modes. An approach to extract height information by radargrammetry was developed, and the commercial distribution of Digital Elevation Models based on TerraSAR-X StripMap and SpotLight Modes (resp. 3m and 1m resolution) has started in 2010. To improve the overall height accuracy of the DEM, acquisitions from both orbit directions are utilised, each point on the ground being thus imaged at least 4 times by TerraSAR-X. Since 2002, Spot Image and French National Cartographic Institute (IGN) are building a worldwide database called Elevation30/Reference3Dô, which includes a Digital Elevation Model at 1-arc-second resolution (DTED level 2) extracted from HRS stereopairs. To answer the wide demand of precise DEMs over Tropical and Northern areas, frequently covered by clouds, a study was performed to integrate StripMap radargrammetric TerraSAR-X data into the Reference3D process, and two prototype products were issued, over Colombia and Congo areas. During this experiment, efforts have been made to stick to technical steps that could be integrated within a standardized production process, in order to keep offering affordable prices while maintaining a high standard of horizontal and vertical accuracy. The DEMs extracted from TerraSAR-X and HRS proved extremely consistent with each other, showing a mean difference of 0.80m. This allows to propose a unified Elevation30 product to the users, with a guaranteed accuracy materialized into the product through a dedicated vertical Accuracy Commitment Mask.
Cunin, 1 L.; Nonin, 2 P.; Janoth, 3 J.; Bernard, 4 M.
The Wind of the B[e] Supergiant Hen S22 Viewed through a Reflection Nebula in DEM L 106
Narrow-band HST WFPC2 images reveal a bow-shock-like halo around the HII\\u000aregion N30B toward the B[e] supergiant Hen S22 located within the larger DEM L\\u000a106 nebula in the Large Magellanic Cloud. High-dispersion spectra of N30B show\\u000aa narrow H-alpha emission component from the ionized gas; the velocity\\u000avariations indicate a gas flow of -5 to -10 km\\/s in the
Y.-H. Chu; C.-H. R. Chen; C. Danforth; B. C. Dunne; R. A. Gruendl; Y. Naze; M. S. Oey
The Discrete Equation Method (DEM) for Fully Compressible Two-Phase Flows in Ducts of Spatially Varying Cross-Section
Typically, multiphase modeling begins with an averaged (or homogenized) system of partial differential equations (traditionally ill-posed) then discretizes this system to form a numerical scheme. Assuming that the ill-posedness problem is avoided by using a well-posed formulation such as the seven-equation model, this presents problems for the numerical approximation of non-conservative terms at discontinuities (interfaces, shocks) as well as unwieldy treatment of fluxes with seven waves. To solve interface problems without conservation errors and to avoid this questionable determination of average variables and the numerical approximation of the non-conservative terms associated with 2 velocity mixture flows we employ a new homogenization method known as the Discrete Equations Method (DEM). Contrary to conventional methods, the averaged equations for the mixture are not used, and this method directly obtains a (well-posed) discrete equation system from the single-phase system to produce a numerical scheme which accurately computes fluxes for arbitrary numbers of phases and solves non-conservative products. The method effectively uses a sequence of single phase Riemann equation solves. Phase interactions are accounted for by Riemann solvers at each interface. Flow topology can change with changing expressions for the fluxes. Non-conservative terms are correctly approximated. Some of the closure relations missing from the traditional approach are automatically obtained. Lastly, we can often times identify the continuous equation system, resulting from taking the continuous limit with weak wave assumptions, of the discrete equations. This can be very useful from a theoretical standpoint. As a first step toward implict integration of the DEM method in multidimensions, in this paper we construct a DEM model for the flow of two compressible phases in 1-D ducts of spatially varying cross-section to test this approach. To relieve time step size restrictions due to stiffness and to achieve tighter coupling of equations, a fully implicit time integration method is employed. For the first time, we demonstrate on a converging-diverging two-phase nozzle that this well-posed, 2 pressure, 2 velocity DEM model can be integrated to a meaningful steady-state with both phases treated as compressible.
Ray A. Berry; Richard Saurel; Tamara Grimmett
Vergleich der Acetylcholinausbeute aus dem Zentralnervensystem des Frosches bei Extraktion mit HCl-Alkohol und Trichloressigs‰ure sowie mittelst Kochen
Zusammenfassung 1.Im Tr.E.-Extrakt des Frosch-Z.N.S. finden sich im Durchschnitt 9? Ac.Ch., d.i. etwa doppelt soviel als im HCl-Alkoholextrakt.2.Die Ursache der Minderausbeute bei HCl-Alkoholextraktion liegt darin, daþ HCl-Alkohol zwar das gesamte Ac.Ch. extrahiert, daþ aber nur ein Teil davon in Ringer ¸bergeht. Beweis daf¸r, daþ saurer Alkohol alles extrahiert, ist, daþ einerseits aus dem im Alkohol unlˆslichen Teil des Z.N.S. mit
O. Loewi; H. Hellauer
Visualising shear stress distribution inside flow geometries containing pharmaceutical powder excipients using photo stress analysis tomography and DEM simulations
NASA Astrophysics Data System (ADS)
For the first time, photo stress analysis tomography (PSAT) is applied to probe the distribution of maximum shear stress and direction of major principal stress field within `powder' assemblies inside hopper geometries, and further supported by discrete element model (DEM) simulations. The results show that for decrease in hopper angle, the direction of major principle stress aligns with the direction of gravity which could promote flow rate under dynamic conditions. Conversely, the propensity of developing relatively more non-homogeneous distribution of shear resistance zones inside powder assemblies increases with the hopper angle, which could subsequently decrease their macroscopic flow rate.
Albaraki, Saeed; Antony, S. Joseph.; Arowosola, C. Babatunde
Post-Merger-Integration als Herausforderung und Chance f¸r den Finanzbereich am Beispiel der Integration des Alstom-Industrieturbinengesch‰fts in den Bereich Power Generation der Siemens AG
Im vorliegenden Beitrag wird die Integration des Finanzwesens im Rahmen des Mergers zwischen dem Gesch‰ftsgebiet Ñ Industrial\\u000a Applicationsì der Siemens Power Generation (PG) und dem Alstom Industrieturbinengesch‰ft beschrieben.
Michael Hafner; Guido Biendarra
DEM-based Approaches for the Identification of Flood Prone Areas
NASA Astrophysics Data System (ADS)
The remarkable number of inundations that caused, in the last decades, thousands of deaths and huge economic losses, testifies the extreme vulnerability of many Countries to the flood hazard. As a matter of fact, human activities are often developed in the floodplains, creating conditions of extremely high risk. Terrain morphology plays an important role in understanding, modelling and analyzing the hydraulic behaviour of flood waves. Research during the last 10 years has shown that the delineation of flood prone areas can be carried out using fast methods that relay on basin geomorphologic features. In fact, the availability of new technologies to measure surface elevation (e.g., GPS, SAR, SAR interferometry, RADAR and LASER altimetry) has given a strong impulse to the development of Digital Elevation Models (DEMs) based approaches. The identification of the dominant topographic controls on the flood inundation process is a critical research question that we try to tackle with a comparative analysis of several techniques. We reviewed four different approaches for the morphological characterization of a river basin with the aim to provide a description of their performances and to identify their range of applicability. In particular, we explored the potential of the following tools. 1) The hydrogeomorphic method proposed by Nardi et al. (2006) which defines the flood prone areas according to the water level in the river network through the hydrogeomorphic theory. 2) The linear binary classifier proposed by Degiorgis et al. (2012) which allows distinguishing flood-prone areas using two features related to the location of the site under exam with respect to the nearest hazard source. The two features, proposed in the study, are the length of the path that hydrologically connects the location under exam to the nearest element of the drainage network and the difference in elevation between the cell under exam and the final point of the same path. 3) The method by Manfreda et al. (2011) that suggested a modified Topographic Index (TIm) for the identification of flood prone area. 4) The downslope index proposed by Hjerdt et al. (2004) that quantifies the topographic controls on hydrology by evaluating head differences following the (surface) flow path in the steepest direction. The method does not use the exit point at the stream as reference; instead, the algorithm looks at how far a parcel of water has to travel along its flow path to lose a given head potential, d [m]. This last index was not defined with the aim to describe flood prone areas; in fact it represents an interesting alternative descriptor of morphological features that deserve to be tested. Analyses have been carried out for some Italian catchments. The outcomes of the four methods are presented using, for calibration and validation purposes, flood inundation maps made available by River Basin Authorities. The aim is, therefore, to evaluate the reliability and the relative errors in the detection of the areas subject to the flooding hazard. These techniques should not be considered as an alternative of traditional procedures, but additional tool for the identification of flood-prone areas and hazard graduation over large regions or when a preliminary identification is needed. Reference Degiorgis M., G. Gnecco, S. Gorni, G. Roth, M. Sanguineti, A. C. Taramasso, Classifiers for the detection of flood-prone areas using remote sensed elevation data, J. Hydrol., 470-471, 302-315, 2012. Hjerdt, K. N., J. J. McDonnell, J. Seibert, A. Rodhe, A new topographic index to quantify downslope controls on local drainage, Water Resour. Res., 40, W05602, 2004. Manfreda, S., M. Di Leo, A. Sole, Detection of Flood Prone Areas using Digital Elevation Models, Journal of Hydrologic Engineering, Vol. 16, No. 10, 781-790, 2011. Nardi, F., E. R. Vivoni, S. Grimaldi, Investigating a floodplain scaling relation using a hydrogeomorphic delineation method, Water Resour. Res., 42, W09409, 2006.
Samela, Caterina; Manfreda, Salvatore; Nardi, Fernando; Grimaldi, Salvatore; Roth, Giorgio; Sole, Aurelia
A new lunar global DEM derived from Chang'E-1 Laser Altimeter data based on crossover adjustment with local topographic constraint
NASA Astrophysics Data System (ADS)
This paper presents a crossover adjustment method with local topographic constraint and a new lunar global digital elevation model (DEM) derived from Chang'E-1Laser Altimeter (LAM) data based on the crossover adjustment. With about 9.12 million altimetric points acquired by the LAM, we derived more than 141,000 crossovers that cover the entire lunar surface after eliminating outliers of orbits and altimetric points. The global lunar surface is divided into 32 local blocks, and the least squares adjustment of crossover differences is performed for each block using the local topographic constraint information extracted from the planar areas. Smooth transitions among the neighbouring blocks are ensured through sufficient overlapping areas and virtual control points from the planar areas. After the crossover adjustment, root mean square (RMS) of the residuals is reduced from 149.51 m to 54.75 m after using three parameters for each profile in each block in the mid-latitude region. In polar regions, RMS is reduced from more than 150 m to less than 100 m after using seven parameters for each profile. The resulting lunar global DEM has a significantly improved quality in the local consistencies, i.e. artefacts in the original DEM are eliminated or decreased. The new lunar global DEM is also compared with the laser altimeter data from NASA's LRO mission and JAXA's KAGUYA mission. After comparison, the result shows that the DEMs are consistent and that adjustment does not deform the lunar terrain.
Hu, Wenmin; Di, Kaichang; Liu, Zhaoqin; Ping, Jinsong
Hydrography change detection: the usefulness of surface channels derived From LiDAR DEMs for updating mapped hydrography
The 1:24,000-scale high-resolution National Hydrography Dataset (NHD) mapped hydrography flow lines require regular updating because land surface conditions that affect surface channel drainage change over time. Historically, NHD flow lines were created by digitizing surface water information from aerial photography and paper maps. Using these same methods to update nationwide NHD flow lines is costly and inefficient; furthermore, these methods result in hydrography that lacks the horizontal and vertical accuracy needed for fully integrated datasets useful for mapping and scientific investigations. Effective methods for improving mapped hydrography employ change detection analysis of surface channels derived from light detection and ranging (LiDAR) digital elevation models (DEMs) and NHD flow lines. In this article, we describe the usefulness of surface channels derived from LiDAR DEMs for hydrography change detection to derive spatially accurate and time-relevant mapped hydrography. The methods employ analyses of horizontal and vertical differences between LiDAR-derived surface channels and NHD flow lines to define candidate locations of hydrography change. These methods alleviate the need to analyze and update the nationwide NHD for time relevant hydrography, and provide an avenue for updating the dataset where change has occurred.
Poppenga, Sandra K.; Gesch, Dean B.; Worstell, Bruce B.
DEM and GIS analysis of the stream gradient index to evaluate effects of tectonics: The Normandy intraplate area (NW France)
NASA Astrophysics Data System (ADS)
Computer-based geomorphometry using a DEM (Digital Elevation Model) allows the analysis of the three-dimensional properties of landscape. This methodology is particularly useful in an intraplate region like western Europe where the simple visual inspection of the topography cannot resolve the evolutionary trends of landforms. In these domains, the morphologies of the topographic surface may be controlled mainly by climate under a low rate of tectonic deformation. Among the geomorphometric parameters, the stream length index ( SL) has been used to characterize fluvial systems in relation to tectonics movements. This work develops an algorithm to derive and map the SL index using a DEM and GIS, to investigate its spatial variations in a broad area. The algorithm is applied to a zone of weak intraplate deformation: the coastal lowlands of Normandy (France). The obtained spatial distributions of SL point to anomalous zones with high SL values. These zones are adjacent to mapped fault scarps and characterized by changes in flow direction. A Kruskal-Wallis test shows that the bedrock lithology has no impact on the SL value. Therefore, the SL variations can be related mainly to a differential uplift due to Quaternary tectonic forcing. Quaternary sea level fluctuations may also be responsible for high SL values in a part of the coastal lowland.
Font, Marianne; Amorese, Daniel; Lagarde, Jean-Louis
Open-source MFIX-DEM software for gas-solids fluidized beds: Part II - Validation studies
With rapid advancements in computer hardware and numerical algorithms, computational fluid dynamics (CFD) has been increasingly employed as a useful tool for investigating the complex hydrodynamics inherent in multiphase flows. An important step during the development of a CFD model and prior to its application is conducting careful and comprehensive verification and validation studies. Accordingly, efforts to verify and validate the open-source MFIX-DEM software, which can be used for simulating the gasñsolids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles, have been made at the National Energy Technology Laboratory (NETL). In part I of this paper, extensive verification studies were presented and in this part, detailed validation studies of MFIX-DEM are presented. A series of test cases covering a range of gasñsolids flow applications were conducted. In particular the numerical results for the random packing of a binary particle mixture, the repose angle of a sandpile formed during a side charge process, velocity, granular temperature, and voidage profiles from a bounded granular shear flow, lateral voidage and velocity profiles from a monodisperse bubbling fluidized bed, lateral velocity profiles from a spouted bed, and the dynamics of segregation of a binary mixture in a bubbling bed were compared with available experimental data, and in some instances with empirical correlations. In addition, sensitivity studies were conducted for various parameters to quantify the error in the numerical simulation.
Li, Tingwen; Garg, Rahul; Galvin, Janine; Sreekanth, Pannala
Landslide-dammed lakes detection via ALOS/PALSAR InSAR DEM: A case study of the Iwate-Miyagi Nairiku earthquake
NASA Astrophysics Data System (ADS)
On 14th June 2008, the Japan Meteorological Agency recorded a 7.2 magnitude (Richter scale) earthquake with an epicenter depth of 8 km in the southern Iwate prefecture of the Tohoku region of Japan. In the hardest hit prefectures of Iwate and Miyagi, the earthquake produced 15 new landslide-dammed lakes; a phenomenon common when the earthquake hypocenter is within inland areas. In our last study, we demonstrated that interferometric SAR (InSAR) technique can detect surface displacements within centimeter accuracy and create detailed three-dimensional terrain information. In this study, we developed a new methodology to detect landslide-dammed lakes using Digital Drainage Models (DDMs) generated from the DEM's cre-ated with InSAR data. Using our technique, small scale topographical change was detected by comparing pre-earthquake DEM's such as created from the Shuttle Radar Topographic Mission (SRTM) data and post-earthquake DEM's created from the Advanced Land Observing System (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) data. Pre-and post-earthquake changes in the drainage networks were detected by comparing DDM features derived from an existing DEM to DDM features derived from a post-earthquake DEM created from ALOS InSAR data. It was verified that landslide-dammed lakes were detected specifically in the area where drainage network with more than three of the river-order computed from DDM's shifted before and after the earthquake. Thus, InSAR DEM generated from ALOS/PALSAR can provide timely and useful spatial information for detecting landslide-dammed lakes.
Asaka, Tomohito; Yamamoto, Yoshiyuki; Iwashita, Keishi; Kudou, Katsuteru; Fujii, Hisao; Nishikawa, Hajime; Sensing Specialist Yukihiro Suzuoki, Remote
The mass balance record and surge behavior of Drangajˆkull Ice Cap (Iceland) from 1946 to 2011 deduced from aerial photographs and LiDAR DEM
NASA Astrophysics Data System (ADS)
High resolution and accuracy (e.g. based on LiDAR survey) Digital Elevation Models (DEMs) of glaciers and their close vicinity have significantly improved the methods for calculation of geodetic mass balance and study of changes in glacier dynamics. However additional data is needed to extend such studies back in time. Here we present a geodetically derived mass balance record for Drangajˆkull ice cap (NW-Iceland) since 1946 to present. The mass balance is calculated from a series of DEMs derived by photogrammetric processing of aerial photographs (years: 1946, 1975, 1985, 1994) and a LiDAR DEM (2011). All Ground Control Points (GCPs) used to constrain the orientation of the aerial photographs, used in the photogrammetric processing, are picked from the LiDAR derived DEM, thus eliminating the time consuming and expensive in situ survey of GCPs. The LiDAR DEM also helps to assess the accuracy of the photogrammetrically derived DEMs, by analyzing the residuals in elevation in ice-free areas. For the DEMs of 1975, 1985 and 1994 the Root Mean Square Error (RMSE) of the residuals is less than 2 m, whereas the accuracy of the DEM of 1946 is worse, with RMSE of 5.5 m, caused by the deteriorated images. The geodetic mass balance yields a negative specific mass balance of ~-0.5 m w.e.a?π for the period 1946-1975, followed by periods of positive mass balance: ~0.2 m w.e.a?π for the period 1975-1985 and ~0.3 m w.e.a?π for the period 1985-1994. Negative specific mass balance of ~-0.6 m w.e.a?π is derived for the period 1994-2011. High mass redistribution is observed during 1985-1994 and 1994-2011 on the three main outlets of the ice cap, related to surges. The derived orthophotographs allow tracking of stable features at individual locations on the northern part of Drangajˆkull, indicating an average velocity of 5-10 m a?π for the period 1946-1985 and speeding up in the last two periods due to a surge.
MuÒoz-Cobo Belart, JoaquÌn; Magn˙sson, EyjÛlfur; P·lsson, Finnur
High Resolution Airborne InSAR DEM of Bagley Ice Valley, South-central Alaska: Geodetic Validation with Airborne Laser Altimeter Data
NASA Astrophysics Data System (ADS)
Bagley Ice Valley, in the St. Elias and Chugach Mountains of south-central Alaska, is an integral part of the largest connected glacierized terrain on the North American continent. From the flow divide between Mt. Logan and Mt. St. Elias, Bagley Ice Valley flows west-northwest for some 90 km down a slope of less than 1o, at widths up to 15 km, to a saddle-gap where it turns south-west to become Bering Glacier. During 4-13 September 2000, an airborne survey of Bagley Ice Valley was performed by Intermap Technologies, Inc., using their Star-3i X-band SAR interferometer. The resulting digital elevation model (DEM) covers an area of 3243 km2. The DEM elevations are orthometric heights, in meters above the EGM96 geoid. The horizontal locations of the 10-m postings are with respect to the WGS84 ellipsoid. On 26 August 2000, 9 to 18 days prior to the Intermap Star-3i survey, a small-aircraft laser altimeter profile was acquired along the central flow line for validation. The laser altimeter data consists of elevations above the WGS84 ellipsoid and orthometric heights above GEOID99-Alaska. Assessment of the accuracy of the Intermap Star-3i DEM was made by comparison of both the DEM orthometric heights and elevations above the WGS84 ellipsoid with the laser altimeter data. Comparison of the orthometric heights showed an average difference of 5.4 +/- 1.0 m (DEM surface higher). Comparison of elevations above the WGS84 ellipsoid showed an average difference of -0.77 +/- 0.93 m (DEM surface lower). This indicates that the X-band Star-3i interferometer was penetrating the glacier surface by an expected small amount. The WGS84 comparison is well within the 3 m RMS accuracy quoted for GT-3 DEM products. Snow accumulation may have occurred, however, on Bagley Ice Valley between 26 August and 4-13 September 2000. This will be estimated using a mass balance model and used to correct the altimeter-derived surface heights. The new DEM of Bagley Ice Valley will provide a reference surface of high accuracy for glaciological and geodetic research using ICEsat and small-aircraft laser altimeter profiling of this glaciologically important region of south-central Alaska.
Muskett, R. R.; Lingle, C. S.; Echelmeyer, K. A.; Valentine, V. B.; Elsberg, D.
Machine vision approach to auto-generation of high resolution, continental-scale geomorphometric map from DEM
NASA Astrophysics Data System (ADS)
Geomorphometric map (GM) is a map of landforms delineated exclusively on the basis of their morphology; it depicts a classification of landscape into its constituent elements. GM is a valuable tool for visual terrain analysis, but more importantly, it's a perfect terrain representation for its further algorithmic analysis. GMs themselves are auto-generated from DEM. We have developed a new technique for auto-generation of GMs that is based on the principle of machine vision. Such approach approximates more closely the mapping process of human analyst and results in an efficient generation of GMs having quality and utility superior to maps generated by a standard technique based on differential geometry. The core of the new technique is a notion of geomorphon. A geomorphon is a relief-invariant, orientation-invariant, and size-flexible abstracted elementary unit of terrain. It is calculated from DEM using simple ternary patterns defined on a neighborhood which size adapts to the character of local terrain. Geomorphons are both terrain attributes and landform types at the same time; they allow for a direct and highly efficient, single-step classification and mapping of landforms. There are 498 unique geomorphons but only a small fraction of them are found in typical natural terrain. The geomorphon-based mapping technique is implemented as a GRASS GIS extension written in ANSI C and will be available in the public domain. In order to showcase the capabilities of geomorphons we have calculated the GM for the entire conterminous United States from the 30m/pixel NED DEM. The map shows ten most abundant landforms: flat, peak, ridge, shoulder, spur, slope, hollow, footslope, valley, and pit; a lookup table was used to assign each of the remaining 488 infrequent forms to a morphologically closest mapped form. The result is a unique, never before seen, type of map that clearly shows multiple geomorphic features and indicates the underlying geologic processes. The auto-generation of GM from this high resolution, continental size raster having 168000x104000 cells took 60 hours on a single processor computer. Future applications of such GM include coupling it with a search tool capable of querying the continental-scale GM in order to identify all instances of a given type of local landscape.
Jasiewicz, J.; Stepinski, T. F.
Analysis of the seasonal and interannual evolution of Jakobshavn Isbrae from 2010-2013 using high spatial/temporal resolution DEM and velocity data
NASA Astrophysics Data System (ADS)
Greenland's large marine-terminating outlet glaciers have displayed marked retreat, speedup, and thinning in recent decades. Jakobshavn Isbrae, one of Greenland's largest outlet glaciers, has retreated ~15 km, accelerated ~150%, and thinned ~200 m since the early 1990s. Here, we present the first comprehensive analysis of high spatial (~2-5 m/px) and temporal (daily-monthly) resolution elevation and velocity data for Jakobshavn from 7/2010 to 7/2013. We have developed an automated processing pipeline using open-source software (Ames Stereo Pipeline, GDAL/OGR, NumPy/SciPy, etc.) to produce orthoimage, digital elevation model (DEM), and surface velocity products from DigitalGlobe WorldView-1/2 stereo imagery (~0.5 m/px, ~17 km swath width). Our timeseries consists of 35 WV DEMs (~2-4 m/px) covering the lower trunks of the main+north branches and fjord, but also extending >110 km inland. We supplement this record with 7 TanDEM-X DEMs (~5 m/px, ~35 km swath width) between 6/2011-9/2012. Elevation data from IceBridge ATM/LVIS, ICESat GLAS, and GPS campaigns provide absolute control data over fixed surfaces (i.e., exposed bedrock). Observed WV DEM offsets are consistent with DigitalGlobe's published value of 5.0 m CE90/LE90 horizontal/vertical accuracy. After DEM co-registration, we observe sub-meter horizontal and vertical absolute accuracy. Velocity data are derived from TerraSAR-X data with 11 day repeat interval. Supplemental velocity data are derived through correlation of high-resolution WV DEM/image data. The contemporaneous DEM and velocity data provide full 3D displacement vectors for each time interval, allowing for the analysis of both Eulerian and Lagrangian elevation change. The lower trunk of Jakobshavn displays significant seasonal velocity variations, with recent rates of ~8 km/yr during winter to >17 km/yr during summer. DEM data show corresponding elevation changes of -30 to -45 m in summer and +15 to +20 m in winter, corresponding to integrated volumes of -1.0 to -1.5 km3 and +0.3 to +0.6 km3 for the lower ~20 km of the main trunk. Further analysis will characterize the upstream propagation of the seasonal elevation change and the relationship with observed strain rates. Seasonal surface mass balance elevation changes are also observed over adjacent grounded, slow-moving (~100 m/yr) regions. The DEM timeseries shows a net interannual thinning trend of -15-20 m/yr for lower Jakobshavn, with decreasing magnitude upstream. This is consistent with long-term altimetry records. Interannual thinning of ~2 m/yr and lateral retreat is also observed for grounded ice sheet margins. These DEM and velocity data capture the timing, magnitude and evolution of dynamic thinning/thickening with unprecedented spatial and temporal resolution. These results also emphasize the importance of dense temporal elevation data when characterizing ice sheet variability and interpreting deviations from long-term records. Similar high-resolution timeseries are available for all major outlet glaciers and ice streams in Greenland and Antarctica. Ultimately, these observations will improve our understanding of outlet glacier behavior, while complementing ongoing efforts to constrain estimates for ice-sheet mass balance and contribution to present/future sea level rise.
Shean, D. E.; Joughin, I. R.; Smith, B. E.; Moratto, Z. M.; Alexandrov, O.; Floricioiu, D.; Morin, P. J.; Porter, C. C.; Beyer, R. A.; Fong, T.
Landsat TM and DEM analysis for geomorphological units discrimination in the area surrounding the Gulf of Naples
NASA Astrophysics Data System (ADS)
In order to compare geomorphological setting and land use, the area enclosing the Gulf of Naples has been investigated. The study has been carried out by analyzing two Landsat TM images, retrieved in 1983 winter and 1987 spring, a regional scale Digital Elevation Model (DEM), aerophotos, topographical and geological maps. The two Landsat TM images have been specifically processed to obtain a broad picture of the changes of land uses during time. In particular, the Tasseled Cap transformation has been computed to get invariant features easy to be related to physical parameters, such as ground moisture, brightness and vegetation density. Moreover, the analysis of these features has allowed the delineation of the irregular development with time of urban areas, especially of Naples, and its interaction with the selected geomorphological units.
Onorati, G.; Ventura, R.; Poscolieri, M.; Cinque, A.
The evaluation of unmanned aerial system-based photogrammetry and terrestrial laser scanning to generate DEMs of agricultural watersheds
NASA Astrophysics Data System (ADS)
Agricultural watersheds tend to be places of intensive farming activities that permanently modify their microtopography. The surface characteristics of the soil vary depending on the crops that are cultivated in these areas. Agricultural soil microtopography plays an important role in the quantification of runoff and sediment transport because the presence of crops, crop residues, furrows and ridges may impact the direction of water flow. To better assess such phenomena, 3-D reconstructions of high-resolution agricultural watershed topography are essential. Fine-resolution topographic data collection technologies can be used to discern highly detailed elevation variability in these areas. Knowledge of the strengths and weaknesses of existing technologies used for data collection on agricultural watersheds may be helpful in choosing an appropriate technology. This study assesses the suitability of terrestrial laser scanning (TLS) and unmanned aerial system (UAS) photogrammetry for collecting the fine-resolution topographic data required to generate accurate, high-resolution digital elevation models (DEMs) in a small watershed area (12 ha). Because of farming activity, 14 TLS scans (? 25 points m? 2) were collected without using high-definition surveying (HDS) targets, which are generally used to mesh adjacent scans. To evaluate the accuracy of the DEMs created from the TLS scan data, 1098 ground control points (GCPs) were surveyed using a real time kinematic global positioning system (RTK-GPS). Linear regressions were then applied to each DEM to remove vertical errors from the TLS point elevations, errors caused by the non-perpendicularity of the scanner's vertical axis to the local horizontal plane, and errors correlated with the distance to the scanner's position. The scans were then meshed to generate a DEMTLS with a 1 ◊ 1 m spatial resolution. The Agisoft PhotoScan and MicMac software packages were used to process the aerial photographs and generate a DEMPSC (Agisoft PhotoScan) and DEMMCM (MicMac), respectively, with spatial resolutions of 1 ◊ 1 m. Comparing the DEMs with the 1098 GCPs showed that the DEMTLS was the most accurate data product, with a root mean square error (RMSE) of 4.5 cm, followed by the DEMMCM and the DEMPSC, which had RMSE values of 9.0 and 13.9 cm, respectively. The DEMPSC had absolute errors along the border of the study area that ranged from 15.0 to 52.0 cm, indicating the presence of systematic errors. Although the derived DEMMCM was accurate, an error analysis along a transect showed that the errors in the DEMMCM data tended to increase in areas of lower elevation. Compared with TLS, UAS is a promising tool for data collection because of its flexibility and low operational cost. However, improvements are needed in the photogrammetric processing of the aerial photographs to remove non-linear distortions.
OuÈdraogo, Mohamar Moussa; DegrÈ, Aurore; Debouche, Charles; Lisein, Jonathan
Numerical slope stability simulations of chasma walls in Valles Marineris/Mars using a distinct element method (dem).
NASA Astrophysics Data System (ADS)
NUMERICAL SLOPE STABILITY SIMULATIONS OF CHASMA WALLS IN VALLES MARINERIS/MARS USING A DISTINCT ELEMENT METHOD (DEM). B. Imre (1) (1) German Aerospace Center, Berlin Adlershof, firstname.lastname@example.com The 8- to 10-km depths of Valles Marineris (VM) offer excellent views into the upper Martian crust. Layering, fracturing, lithology, stratigraphy and the content of volatiles have influenced the evolution of the Valles Marineris wallslopes. But these parameters also reflect the development of VM and its wall slopes. The scope of this work is to gain understanding in these parameters by back-simulating the development of wall slopes. For that purpose, the two dimensional Particle Flow Code PFC2D has been chosen (ITASCA, version 2.00-103). PFC2D is a distinct element code for numerical modelling of movements and interactions of assemblies of arbitrarily sized circular particles. Particles may be bonded together to represent a solid material. Movements of particles are unlimited. That is of importance because results of open systems with numerous unknown variables are non-unique and therefore highly path dependent. This DEM allows the simulation of whole development paths of VM walls what makes confirmation of the model more complete (e.g. Oreskes et al., Science 263, 1994). To reduce the number of unknown variables a proper (that means as simple as possible) field-site had to be selected. The northern wall of eastern Candor Chasma has been chosen. This wall is up to 8-km high and represents a significant outcrop of the upper Martian crust. It is quite uncomplex, well-aligned and of simple morphology. Currently the work on the model is at the stage of performing the parameter study. Results will be presented via poster by the EGS-Meeting.
Imre, B.
Suitability evaluation of fruit trees in Fujian southern mountain areas based on DEM and GIS using a multi-criteria evaluation approach
The application of a multicriteria evaluation (MCE) approach to identify suitable areas for the production of banana, lichee and longyan in Southeast of Fujian Province in China is presented. Climate, terrain and soil databases were used to integrate GIS coverage. Because of the varied topography of Fujian province, the yearly average temperature and minimum temperature were modeled through DEM for
Qiu Bingwen; Chi Tianhe; Wang Qinmin; Wang Xiaoqin; Lan Zhangren
Jakobshavn Isbrae, Greenland: DEMs, orthophotos, surface velocities, and ice loss derived from photogrammetric re-analysis of July 1985 repeat aerial photography
NASA Astrophysics Data System (ADS)
Jakobshavn Isbrae drains about 7 % of the Greenland Ice Sheet and is the ice sheet's largest outlet glacier. Two sets of high elevation (~13,500 m), high resolution (2 m) aerial photographs of Jakobshavn Isbrae were obtained about two weeks apart during July 1985 (Fastook et al, 1995). These historic photo sets have become increasingly important for documenting and understanding the dynamic state of this outlet stream prior to the rapid retreat and massive ice loss that began in 1998 and continues today. The original photogrammetric analysis of this imagery is summarized in Fastook et al. (1995). They derived a coarse DEM (3 km grid spacing) covering an area of approximately 100 km x 100 km by interpolating several hundred positions determined manually from block-aerial triangulation. We have re-analyzed these photos sets using digital photogrammetry (BAE Socet Set©) and significantly improved DEM quality and resolution (20, 50, and 100 m grids). The DEMs were in turn used to produce high quality orthophoto mosaics. Comparing our 1985 DEM to a DEM we derived from May 2006 NASA ATM measurements showed a total ice volume loss of ~ 105 km3 over the lower drainage area; almost all of this loss has occurred since 1997. Ice stream surface velocities derived from the 1985 orthomosaics showed speeds of 20 m/d on the floating tongue, diminishing to 5 m/d at 50 km further upstream. Velocities have since nearly doubled along the ice stream during its current retreat. Fastook, J.L., H.H. Brecher, and T.J. Hughes, 1995. J.of Glaciol. 11 (137), 161-173.
Motyka, R.; Fahnestock, M.; Howat, I.; Truffer, M.; Brecher, H.; Luethi, M.
Estimation of mass change rates of surge-type glaciers in the Karakoram derived from TanDEM-X and SRTM Digital Elevation Models
NASA Astrophysics Data System (ADS)
Glaciers in the Karakoram region exhibit stable and advancing termini positions accompanied by less negative or even positive surface mass balances in comparison to the adjacent Greater Himalaya Range and the Hindu Kush mountains. Moreover, a large number of surge-type glaciers is found in the Karakoram. During the active phase of a surge, ice masses are shifted from the reservoir area towards the receiving area of a glacier. Remote sensing based methods provide various possibilities to identify surge-type glaciers (termini position changes, surface velocity variations, mass changes), where in-situ measurements are hardly available. The present study focuses on glacier mass changes in the Karakoram between 2000 and 2013 derived from DEM differencing. We used the C-band SRTM DEM (February, 2000) and high resolution TanDEM-X data (2011-2013). Due to quasi bi-static image acquisitions, TanDEM-X data is very suitable for interferometric elevation generation minimizing decorrelation impacts. However, influences of different penetration depths of X- and C-band have to be considered. We quantified glacier volume and mass changes for the central part of the Karakoram for a twelve year period. For a surge-type glacier in the Shimshal Valley we observed a mass relocation of 2.96±2.52 m/a w.e. close to its snout between 2000 and 2012. Further case studies will be presented including annual mass changes (2011-2013) determined using repeat TanDEM-X acquisitions. In addition to interannual surface velocity changes, mass change observations can help to obverse the propagation of the surge front down-glacier and quantify the relocation of mass during an active surge phase.
Rankl, Melanie; Braun, Matthias; Vijay, Saurabh
Site-specific assessment of the rockfall and the rock block volume distribution relations, using a LIDAR generated DEM
NASA Astrophysics Data System (ADS)
The quantification of the rockfall hazard and, in particular of the rockfall propagation, requires information on the expected probability or frequency of rockfalls of a given magnitude (size), usually in the form of magnitude-frequency M-F relations. Two kinds of relations are needed. The first one characterises the rockfall masses that can be potentially detached from the slope face giving information on the volume distribution of rockfalls. From now on, this will be referred to as potential rockfall volume distribution VDR. For fragmental rockfalls, the evaluation of the VDR can be a first step towards the temporal M-F, The second one characterises the volume distribution of the rock blocks that result from the disintegration of the previous rockfall masses due to impact with the ground. This one will be referred to as rock block volume distribution VDB. In this work we present two analytical procedures which are independent from the existence of empirical data, for: (i) The calculation of the potential VDR that refers to big volumes with low probability of occurrence. This is realised by detection of the kinematically unstable surfaces on a DEM and on orthophotos, and calculation of the volumes that correspond to them. The basic assumptions here describing a conservative scenario of very low probability are: (a) the rockfall mass is detached entirely at a single rockfall event, without taking into account that smaller successive failures are possible instead; (b) all discontinuity sets are present everywhere in the slope and have infinite persistence; and (c) big stepped-path failures are possible. (ii) The assessment of the in-situ rock blocks volume distribution on the slope face, VDB, by calculation of the volume of the prisms which are formed by the intersection of the existing discontinuity sets and are kinematically unstable. This is also based on data obtained by DEM analysis. A high-resolution DEM obtained by Lidar is used. Both procedures are presented though an application example at the country of Andorra and in particular at the chute of Forat Negre. The results from the first procedure indicate that it is kinematically possible to have mobilised volumes of some thousands of cubic meters although the probability of generating large volumes is low. The VDR for big volume events was well fitted by a power-law equal to -0.5. The VDB from the second procedure, assuming three intersection types within the discontinuity network and two extreme cases of discontinuity persistence, was also found to follow a power-law, with exponent -1.3. The comparison with field data collected by past studies in the same area indicates that in reality, the discontinuities have a very high persistence and that considering only their visible trace length is very conservative.
Mavrouli, Olga; Corominas, Jordi; Jaboyedoff, Michel
Studium der Station‰ren und Laufenden Schichtung in der Entladung in Neon Mit Hilfe eines Lokalen Hochfrequenzfeldes
Zusammenfassung Es wurde ein Verfahren zur Erregung von station‰ren Schichten, der Schichtungswelle und der laufenden Schichten in der Gleichstromentladung ausgearbeitet, das auf der Einwirkung eines Hochfrequenzfeldes auf einen kurzen Abschnitt der positiven S‰ule beruht. Dieses Verfahren wurde zum Studium aller drei angef¸hrten Schichtungsarten in Neon ben¸tzt, insbesondere jedoch zum Studium des Zusammenhanges zwischen den laufenden und den station‰ren Schichten.
M. äÌcha; V. Vesel˝; J. Studnicka; J. Prostejovsk˝; M. Nov·k
Elevation Change of Greenland's Jakobshavn Glacier from ICESat, IceBridge Altimetry and TerraSAR-X DEMs
NASA Astrophysics Data System (ADS)
The recent accelerated ice mass loss of the Greenland ice sheet, and its outlet glacier in particular, has been widely documented. The Jakobshavn Isbrae/Glacier is one of the fastest melting and retreating glaciers in Greenland. Recent observations from the laser altimetry mission ICESat (2003-2009) and the airborne campaigns of the IceBridge project (2009-2011) were used to determine Jakobshavn's total elevation change for those time periods as well as annual elevation change rates. TerraSAR-X data acquired in 2009 were processed to form 3 m horizontal resolution digital elevation models (DEM), which were constrained using ICESat measurements. The elevation change results confirm previously determined rates of several decimeters per year of elevation loss. More specifically, while the outlet glacier shows elevation loss of up to several meters per year, the higher elevation areas of the ice sheet exhibit only a few decimeters per year loss and even elevation gain for some years. The study area below 1500 m elevation shows elevation change rates between -0.5 to -2.5 m/yr, the higher elevation area exhibits a much decreased rate between +0.34 and -0.55 m/yr. The Jakobshavn outlet glacier showed a consistently increasing elevation change rate of -3.0 to -5.0 m/yr between 2003 and 2011. It demonstrates that both ICESat and IceBridge observations allow for the accurate estimation of elevation change rates with uncertainties of less than 0.5 m/yr standard deviation. The major contributor to the uncertainty is the slope correction needed to project two footprints at different epochs onto a common location. The slope correction was applied based on the DEMs from ICESat and TerraSAR-X data or the IceBridge slope measurements. Both ICESat and IceBridge observations are able to demonstrate the variations in annual and seasonal elevation change rates exceeding 0.5 m/yr, a rate which is by far exceeded for low-elevation areas below 1500 m. By having an improved understanding of annual and seasonal variability of elevation change, the mass balance of the Jakobshavn glacier can be better assessed towards quantifying its contribution to sea level change.otal elevation change between early-summer 2009 and early-summer 2011 from IceBridge data along the flight tracks.
Qi, W.; Braun, A.
Topographic changes due to the 2008 Mw 7.9 Wenchuan earthquake as revealed by the differential DEM method
NASA Astrophysics Data System (ADS)
Landscape evolution in active orogenic regions is inevitably affected by the repeated strong earthquakes triggered by the corresponding active faults. However, the lack of adequate methods for the documentation and monitoring of mountain-building processes has resulted in a shortage of quantitative estimates of orogenic and eroded volumes. A strong earthquake and its associated co-seismic landslides represent a sudden pulse in landscape evolution in tectonically active areas. The 2008 Mw 7.9 Wenchuan earthquake dramatically modified the topography of the Longmen Shan region. Based on topographic data before the earthquake and stereo pairs of post-earthquake remote sensing imagery, we derived pre- and post-earthquake DEMs (digital elevation models) of the three regions along the Longmen Shan Thrust Belt. By comparing the geomorphic features before and after the earthquake, we find that the Wenchuan earthquake smoothed the steep relief and caused a co-seismic uplift of the Longmen Shan region. The medium-relief regions increased; however, the high-relief regions decreased, indicating that the local relief is controlled by repeated strong earthquakes. The changed slope aspect indicates that the formation and modification of the east- and west-facing slopes are controlled by tectonic events in the Longmen Shan region, which might be associated with the regional stress field. However, the unchanged aspects of other slopes might be controlled by long-term erosion rather than tectonic events. The topographic changes, landslide volume and co-seismic uplift indicate that the greatest seismically induced denudation occurred in association with a thrust faulting mechanism and low-angle fault geometry. Our findings reveal that the local relief has been shaped by the localized, seismically induced high rate of denudation within the plateau margins, and that the formation of local relief is also related to tectonic events, especially the events that have occurred on low-angle faults. This study also indicates that the multi-temporal DEM differential method is valuable in detecting seismically induced topographic change.
Ren, Zhikun; Zhang, Zhuqi; Dai, Fuchu; Yin, Jinhui; Zhang, Huiping
Characterization of the Sediment Routing System of the Argentine Las PeÒas Thrust From ASTER Imagery Interpretation and DEM Terrain Analysis
NASA Astrophysics Data System (ADS)
In an arid region north of Mendoza, Argentina active structures of the Precordilleran fold and thrust belt control sedimentation in the proximal Andean foreland basin. Initiation of new thrust faults and along-strike growth of fault-propagation folds drives uplift of hanging-wall source areas. Drainage basin initiation and development in the Las PeÒas thrust hanging-wall triggers erosion of sediment, controlling transport and depositional mechanisms in the associated alluvial fan system. Alluvial fans are classified as either sheetflood or debris-flow fans based on the areally dominant process responsible for producing the sediment wedge as recorded in the surface character and morphology of the fans. Traditionally, information about these systems has been directly measured using manual methods such as ground surveying and visible image interpretation. This study implements remote sensing with ASTER spectral data and derived topographic data to characterize both fan surfaces and drainage basins. AST14DMO data include fourteen ASTER Level-1B calibrated nadir looking radiance bands at 15-m (VNIR), 30-m (SWIR) and 90-m (TIR) resolution. AST14DMO also includes the ASTER 30-m Digital Elevation Model (DEM) derived from stereoscopic data from the VNIR sensor. These bands were used in rule-based classification implemented in statistical software. The classification was used for mapping and measuring the patterns and spectral characteristics of fan surfaces. TIR and VNIR explanatory variables in decision trees highlighted differences in fan environmental variables including soil conditions, sediment size, and vegetation (moisture, roughness, and composition) indicative of process and rate of deposition on alluvial fans. Terrain Analysis conducted with the ASTER 30-m DEM focused on morphology of the drainage basin sector of the sediment routing system. Drainage basin characteristics including areal extent, slope, aspect, hypsometric curves, and bedrock geology were identified and compared. The information was used to interpret transport and depositional mechanisms within the system, as well as identify source materials and possible ranges of fluid-sediment concentrations for each basin. The geometry of the developing Las PeÒas thrust controls attributes of both drainage basin source areas, and alluvial fan depositional environments as shown by their variation along the fault. The techniques and setting of this study inform interpretations of processes active in modern systems that are applicable to ancient systems on Earth and elsewhere.
Abrahamson, I. S.; Schmitt, J.
Analysis of landslide development using aerial photographs and DEMs comparison, along part of the Chacoura River valley, Quebec, Canada.
NASA Astrophysics Data System (ADS)
The large plains of Eastern Canada sensitive clays are cut by numerous rivers, in a way that their slopes have been and are still affected by landslides. They play an important role in the modelling of the landscape of these regions. Hence, the role of erosion as a trigger of landslides is important. On the Chacoura River, north of Louiseville (Quebec), several large landslides scars, more or less recent, are visible. A first inventory of areas of erosion, slides and landslides clay was carried out by Locat et al. (1984) on some series of aerial photographs covering a period from 1948 to 1979. This study is based on a detailed analysis of aerial photographs, dating from 1948 to 1997 and an airborne LiDAR digital elevation model (DEM-LiDAR), dating from 2007, in a GIS environment, using two different approaches: (1) a map of the phenomena was drawn by identifying various elements such as land movements, limits of the slope, position of the river, the area covered by forest and agricultural drainage structures, e.g., and (2) the comparison of DEMs was performed to estimate slipped and eroded volumes, the rate of erosion on a section of the river (about 6 km) and the spatial distribution of movements. The results show that the location of landslides is directly linked to the presence of some characteristic topographical features, such as (1) the shape of the meandering river, (2) the flow of agricultural drainage, or (3) the erosion at the toe of the slope. Finally, the study of landslides over a period of 60 years shows that the major landslide scars in this area could be in fact the sum of several events of lesser importance. For example, a large landslide (around 13'000 m2) occurred in 1976 at the same place where a first landslide of 1500 m2 in 1964. Locat, J., Demers, D., Lebuis, J. and Rissmann, P. (1984), PrÈdiction des Glissements de Terrain; Application aux Argiles Sensibles, RiviËre Chacoura, QuÈbec, Canada, the IV International Symposium on Landslides Toronto 1984 Proceedings, Volume II, pp 549-555.
LÈvy, S.; Locat, J.; Jaboyedoff, M.; Demers, D.; Loye, A.
Developing sub 5-m LiDAR DEMs for forested sections of the Alpine and Hope faults, South Island, New Zealand: Implications for structural interpretations
NASA Astrophysics Data System (ADS)
Kilometre-wide airborne light detection and ranging (LiDAR) surveys were collected along portions of the Alpine and Hope faults in New Zealand to assess the potential for generating sub 5-m bare earth digital elevation models (DEMs) from ground return data in areas of dense rainforest (bush) cover as an aid to mapping these faults. The 34-km long Franz-Whataroa LiDAR survey was flown along the densely-vegetated central-most portion of the transpressive Alpine Fault. Six closely spaced flight lines (200Ým apart) yielded survey coverage with double overlap of swath collection, which was considered necessary due to the low density of ground returns (0.16Ým-2 or a point every 6Ým2) under mature West Coast podocarp-broadleaf rainforest. This average point spacing (?2.5Ým) allowed for the generation of a robust, high quality 3-m bare earth DEM. The DEM confirmed the zigzagged form of the surface trace of the Alpine Fault in this area, originally recognised by Norris and Cooper (1995, 1997) and highlights that the surface strike variations are more variant than previously mapped. The 29-km long Hurunui-Hope LiDAR survey was flown east of the Main Divide of the Southern Alps along the dextral-slip Hope Fault, where the terrain is characterised by lower rainfall and more open beech forest. Flight line spacings of ?275Ým were used to generate a DEM from the ground return data. The average ground return values under beech forest were 0.27Ým-2 and yielded an estimated cell size suitable for a 2-m DEM. In both cases the LiDAR revealed unprecedented views of the surface geomorphology of these active faults. Lessons learned from our survey methodologies can be employed to plan cost-effective, high-gain airborne surveys to yield bare earth DEMs underneath vegetated terrain and multi-storeyed canopies from densely forested environments across New Zealand and worldwide.
Langridge, R. M.; Ries, W. F.; Farrier, T.; Barth, N. C.; Khajavi, N.; De Pascale, G. P.
Electrochemical behavior of sodium azide at Pt and Au electrodes in sodium sulfate electrolyte: A DEMS study
Azides are widely used in chemical technology for a large variety of applications, such as detonators (Pb(N{sub 3}){sub 2}), getters in electric discharge tubes, anticorrosive agents, or additives for the production of foam rubber. The electro-oxidation and -reduction of sodium azide at porous painted platinum and gold electrodes was studied using the multipurpose electrochemical mass spectrometry (MPEMS) which was operated in the differential electrochemical mass spectrometry (DEMS) mode. The platinum electrode was found to be active for electro-oxidation as well as for electroreduction. Above 0.3 V vs. Hg/Hg{sub 2}SO{sub 4}, azide is oxidized to give N{sub 2}, NO, NO{sub 2}, and N{sub 2}O. Reduction of azide takes place below {minus}0.9 V forming N{sub 2}, N{sub 2}H{sub 4}, and possibly NH{sub 3}. In contrast to platinum, gold showed only activity for the electro-oxidation of azide leading to the formation of N{sub 2}, NO, NO{sub 2}, and N{sub 2}O above 0.5 V. Evidence for a reaction without evolution of volatile products was also found taking place above 0.1 V. A reaction mechanism is discussed emphasizing the role of adsorbed hydrogen and oxygen.
Dalmia, A.; Wasmus, S.; Savinell, R.F.; Liu, C.C. [Case Western Reserve Univ., Cleveland, OH (United States)
Body Mass Index in Different Dementia Disorders: Results from the Swedish Dementia Quality Registry (SveDem)
Background Most patients with dementia lose body weight over the course of the disease and have a lower body mass index (BMI) than subjects with normal cognition. Aims To examine body mass index and how it correlates with cognitive status, age and gender in patients with different dementia disorders. Materials and Methods Data from newly diagnosed dementia patients in the Swedish Dementia Quality Registry (SveDem) and recorded information about age, gender, cognitive status and BMI was analyzed using independent samples t tests and one-way analysis of variance. Results A total of 12,015 patients, 7,121 females and 4,894 males were included in the study. The average BMI was 24. More than a quarter of the patients had a BMI of <22. Females were significantly older (p < 0.001) and males had a significantly higher BMI (p < 0.001) at the time of diagnosis. BMI differed significantly by gender in various dementia disorders and correlated significantly with cognitive status and age. Conclusion At the time of diagnosis, patients with various dementia disorders had a BMI within the normal range. However, a significant number had a BMI in a lower, suboptimal range for older persons stressing the need for nutritional assessment as part of the dementia work up. Further analyses with longitudinal follow-up are needed to investigate BMI changes over time.
Faxen-Irving, Gerd; Fereshtehnejad, Seyed-Mohammad; Falahati, Farshad; Cedergren, Lars; Goranzon, Helen; Wallman, Kristine; Garcia-Ptacek, Sara; Eriksdotter, Maria; Religa, Dorota
Das L‰ngenwachstumsverhalten nach Oberschenkelschaftfraktur im Kindesalter
ZusammenfassungÝÝAus dem Krankengut der Universitttsklinik fr Unfallchirurgie Innsbruck wurden 75 Kinder, die bis zum 15. Lebensjahr eine\\u000a siolierte Oberschenkelschaftfraktur erlitten, einer zweimaligen Nachuntersuchung mit radiologischer Lngenmessung unterzogen.\\u000a Der Zeitraum, zwischen erster und zweiter Messung betrug in allen konservativ behandelten Fllen genau vier Jahre. 60 Patienten\\u000a wurden konservativ, 15 operativ behandelt. Kinder unter dem zehnten Lebensjahr und zwischen dem elften und
K. Golser; H. Resch; G. Sperner; H. Thˆni
User evaluation of the DEMentia-specific Digital Interactive Social Chart (DEM-DISC). A pilot study among informal carers on its impact, user friendliness and, usefulness
Objective: The need for information about the disease and coping with the consequences, as well as on available care and welfare services, is frequently unmet in people with dementia and their carers. To provide carers of community-dwelling people with dementia with tailored information, the DEMentia-specific dynamic interactive social chart (DEM-DISC) was developed. The impact on the daily life of people
HenriÎtte G. van der Roest; Franka J. M. Meiland; Cees Jonker; Rose-Marie Drˆes
A parametric study on the leakage-soil interaction due to a leaking pipe using the coupled DEM-LBM technique
NASA Astrophysics Data System (ADS)
The coupled DEM-LBM technique is employed to simulate the leakage-soil interaction due to a leaking pipe. By adopting various particle surface energy values, the mechanical effect of soil cohesion is explored. It is found out that the orifice pressure drops with time after fluidisation occurs. And a stronger adhesion force leads to a slower decrease. In addition, the cavity size at a given time linearly decreases with the increase in the adhesion force between particles.
Cui, X.; Li, J.; Chan, A. H. C.; Chapman, D. N.
Mapping SOC content and bulk density of a disturbed peatland relict with electromagnetic induction and DEM data
NASA Astrophysics Data System (ADS)
Peatlands represent a huge storage of soil organic carbon (SOC), and there is considerable interest to assess the total amount of carbon stored in these ecosystems. However, reliable field-scale information about peat properties, particularly SOC content and bulk density (BD) necessary to estimate C stocks, remains difficult to obtain. A potential way to acquire information on these properties and its spatial variation is the non-invasive mapping of easily recordable physical variables that correlate with peat properties, such as bulk electrical conductivity (ECa) measured with electromagnetic induction (EMI). However, ECa depends on a range of soil properties, including BD, soil and water chemistry, and water content, and thus results often show complex and site-specific relationships. Therefore, a reliable prediction of SOC and BD from ECa data is not necessarily given. In this study, we aim to explore the usefulness of Multiple Linear Regression (MLR) models to predict the peat soil properties SOC and BD from multi-offset EMI and high-resolution DEM data. The quality of the MLR models is assessed by cross-validation. We use data from a medium-scale disturbed peat relict (approximately 35ha) in Northern Germany. The potential explanatory variables considered in MLR were: EMI data of six different integral depths (approximately 0.25, 0.5, 0.6, 0.9, 1, and 1.80 m), their vertical heterogeneity, as well as several topographical variables extracted from the DEM. Ground truth information for SOC, BD content and peat layer thickness was obtained from 34 soil cores of 1 m depth. Each core was divided into several 5 to 20 cm thick layers so that integral information of the upper 0.25, 0.5, and 1 m as well as from the total peat layer was obtained. For cross-validation of results, we clustered the 34 soil cores into 4 classes using K-means clustering and selected 8 cores for validation from the clusters with a probability that depended on the size of the cluster. With the remaining 26 samples, we performed a stepwise MLR and generated separate models for each depth and soil property. Preliminary results indicate reliable model predictions for SOC and BD (R≤ = 0.83- 0.95). The RMSE values of the validation ranged between 3.5 and 7.2 vol. % for SOC and 0.13 and 0.37 g/cm≥ for BD for the independent samples. This equates roughly the quality of SOC predictions obtained by field application of vis-NIR (visible-near infrared) presented in literature for a similar peatland setting. However, the EMI approach offers the potential to derive information from deeper depths and allows non-invasive mapping of BD variability, which is not possible with vis-NIR. Therefore, this new approach potentially provides a more useful tool for total carbon stock assessment in peatlands.
Altdorff, Daniel; Bechtold, Michel; van der Kruk, Jan; Tiemeyer, B‰rbel; von Hebel, Christian; Huisman, Johan Alexander
Ethylene glycol electrooxidation on carbon supported Pt, PtRu and Pt 3Sn catalystsóA comparative DEMS study
NASA Astrophysics Data System (ADS)
We present results of a comparative study on the interaction of ethylene glycol (EG) with carbon supported Pt, PtRu and Pt 3Sn nanoparticle catalysts, employing electrochemical and quantitative differential electrochemical mass spectroscopy (DEMS) measurements under continuous reaction and continuous electrolyte flow conditions. For all three catalysts EG adsorption is inhibited at very cathodic adsorption potentials, dissociative adsorption starts above 0.06 V and increases with increasing potential. Based on the electron yield per formed CO 2 molecule and on the similarity with the CO ad stripping characteristics CO ad is identified as the main stable adsorbate; the relative coverage in terms of adsorbed C1 species, relative to that of a saturated CO adlayer on the respective catalyst, reaches a maximum of ca. 0.6 at around 0.4 V on Pt/Vulcan, ca. 0.2 at around 0.2 V on PtRu/Vulcan and ca. 0.4 at around 0.35 V on Pt 3Sn/Vulcan. Bulk EG electrooxidation under steady-state conditions shows a very small current efficiency for CO 2 formation of below 6% for 0.1 M EG on all three catalysts, the oxidation of EG mainly generates partly oxidized C2 by-products. Catalyst modification by Ru or Sn improves the activity for EG oxidation at low potentials (?0.56 V), but does not lead to better selectivities for complete EG oxidation to CO 2 at potentials with significant oxidation rates. Hence, C-C bond breaking is rate limiting for complete oxidation under present reaction conditions for all three catalysts. The data are consistent with a parallel pathway reaction mechanism, with formation and subsequent oxidation of CO ad in the one pathway and partial oxidation, via a sequence of reaction steps, to increasingly oxidized C2 species in the other pathway.
Wang, H.; Zhao, Y.; Jusys, Z.; Behm, R. J.
NSDL National Science Digital Library
Today, you will practice solving fraction problems! First, be sure you have SCRATCH PAPER and a PENCIL to help solve each problem. You will need to solve FIVE problems on your paper. You MUST show your work! Be sure to reduce your fraction to the LOWEST terms. GOOD LUCK! CLICK HERE -->Add Those Fractions! Once you have practiced adding fractions, ...
Smith, Ms.
NSDL National Science Digital Library
Today, you are going to practice finding multiples and adding fractions! FIRST, you will practice finding multiples with the Mayor of Pumpkinville. You will START with finding multiples of 2. THEN, you will find multiples of 3 through 12. Once you have TEN multiples of EACH number, you may move to the next game! GOOD LUCK! CLICK HERE -->Pumpkin Multiples Once you have ...
Smith, Ms.
Differential Movement across Byrd Glacier, Transantarctic Mountains, Antarctica: A combined (U-Th)/He and DEM Analysis
NASA Astrophysics Data System (ADS)
Byrd Glacier, a major outlet glacier crossing the Transantarctic Mountains (TAM), marks a major discontinuity in the Neoproterozoic-early Paleozoic Ross orogen, with plutonic and upper-amphibolite metamorphic rocks to the north and folded limestones and conglomerates to the south. The objectives of this study are to assess possible differential movement across an inferred fault under Byrd Glacier, measure the timing of unroofing, and gain an overall better understanding of the architecture of the TAM. One datum for assessing possible differential movement in this area is the Kukri peneplain: an unconformity on the Ross basement rocks, which is overlain by Devonian to Triassic sediments and only mildly deformed. To determine the timing of unroofing, euhedral apatites separated from rock samples collected from a variety of elevations and locations north and south of Byrd Glacier were dated using single crystal (U-Th)/He thermochronology. The (U-Th)/He data reveal distinct cooling histories north and south of Byrd Glacier. Data on age vs. elevation plots indicate an offset of ~1 km across Byrd Glacier with a common denudation rate of ~0.04 mm/yr between 180 - 40 Ma. Two models plausibly explain this geochronologic data. In the first model, a relative uniform unroofing across Byrd Glacier is offset by later fault displacement; the second model involves differential unroofing with the north side exhumed earlier than the south side. To test the relative merits of these models, we utilize the Kukri peneplain. A Landsat image of the Byrd Glacier area was overlain on Aster Global DEM data and spot elevations of the Kukri peneplain to the north and south of Byrd Glacier were mapped where possible. The difference in elevation of the peneplain as projected in a cross section across Byrd Glacier shows an offset of approximately 550 m. The results of this study suggest a model of relatively uniform unroofing with later fault displacement that uplifted the south side relative to the north side. This method of combining geochronologic and remote geomorphic analysis, utilizing a peneplain as a datum, has provided insight into a likely unroofing model, denudation history, and better understanding of differential movement, which can complement other thermochronologic studies elsewhere within the TAM.
Foley, D. J.; Stump, E.; van Soest, M. C.; Whipple, K. X.; Hodges, K.
Intercomparison of DEM-based approaches for the identification of flood-prone areas in different geomorphologic and climatic conditions
NASA Astrophysics Data System (ADS)
Floods represent the most critical natural hazard for many countries and their frequency appears to be increasing in recent times. The legal constraints of public administrators and the growing interest of private companies (e.g., insurance companies) in identifying the areas exposed to the flood risk, is determining the necessity of developing new tools for the risk classification over large areas. Nowadays, among the numerous hydrologic and hydraulic methods regularly used for practical applications, 2-D hydraulic modeling represents the most accurate approach for deriving detailed inundation maps. Nevertheless, data requirement for these modeling approaches is certainly onerous, limiting their applicability over large areas. On this issue, the terrain morphology may provide an extraordinary amount of information useful to detect areas that are particularly prone to serious flooding. In the present work, we compare the reliability of different DEM-derived quantitative morphologic descriptors in characterizing the relationships between geomorphic attributes and flood exposure. The tests are carried out using techniques of pattern classification, such as linear binary classifiers (Degiorgis et al., 2012), whose ability is evaluated through performance measures. Simple and composed morphologic features are taken into account. The morphological features are: the upslope contributing area (A), the local slope (S), the length of the path that hydrologically connects the location under exam to the nearest element of the drainage network (D), the difference in elevation between the cell under exam and the final point of the same path (H), the curvature (downtriangle2H). In addition to the mentioned features, the study takes into consideration a number of composed indices, such as: the modified topographic index (Manfreda et al., 2011), the downslope index (DI) proposed by Hjerdt et al. (2004), the ratio between the elevation difference H and the distance to the network D, and other indices. Each binary classifier is applied in several catchments in order to verify the reproducibility of the procedures in different geomorphologic, climatic and hydrologic conditions. The study explores the use of these procedures in gauged river basins located in Italy and in an ungauged basin located in Africa. References Degiorgis, M., G. Gnecco, S. Gorni, G. Roth, M. Sanguineti, A.C. Taramasso, 2012. Classifiers for the detection of flood-prone areas using remote sensed elevation data, J. Hydrol., 470-471, 302-315. Hjerdt, K. N., J.J. McDonnell, J. Seibert, A. Rodhe, A new topographic index to quantify downslope controls on local drainage, Water Resour. Res., 40, W05602, 2004. Manfreda, S., M. Di Leo, A. Sole, Detection of Flood Prone Areas using Digital Elevation Models, J. Hydrol. Eng., 16(10), 781-790, 2011.
Samela, Caterina; Nardi, Fernando; Grimaldi, Salvatore; De Paola, Francesco; Sole, Aurelia; Manfreda, Salvatore
Tracking and evolution of irrigation triggered active landslides by multi-source high resolution DEM: The Jiaojiacun landslide group of Heifangtai (Northwest of China)
NASA Astrophysics Data System (ADS)
The construction of three large hydropower stations, i.e. Liujia, Yanguo and Bapan, resulted in the immigration of the impacted people to Heifangtai from 1960s. To support the living and farming of the immigrated people, a large amount of water has been pumped from the Yellow River to Heifangtai, which has changed the former underground water budget and led to 111 landslides from 1968 in this area. To reveal the deformation process of landslides in Heifangtai, a quantitative deformation analysis model of landslide based on multi-source DEM data is established using four periods of topographic maps obtained in 1970, 2001, 2010 and 2013 respectively, including two 1:10000 topographic maps and two 1:1000 data acquired from 3D Laser Scanner. The whole study area was divided into two sections based on the two distinct kinds of landslide patterns. The selected morphometric parameters, residual topographic surface and surface roughness, extracted from three typical landslides, and the statistical analysis (Box-plot diagrams) of the temporal variations of these parameters, allowed the reconstruction and tracking of these landslides. We monitored the changing of landslide boundaries, average vertical and horizontal displacement rates and zones of uplift and subsidence. The volumes of removed and/or accumulated material were estimated as well. We can then demonstrate the kinematics of landslides based on information from high-resolution DEM, and the changing table of underground water, ring-shear test and soil-water characteristic curve referenced from other researchers. The results provide a new insight on the use of multi-source high resolution DEM in the monitoring of irrigation-triggered landslides.
Zeng, Runqiang; Meng, Xingmin; Wang, Siyuan; Chen, Guan; Lee, Yajun; Zhang, Yi
Seasonal variabilty of surface velocities and ice discharge of Columbia Glacier, Alaska using high-resolution TanDEM-X satellite time series and NASA IceBridge data
NASA Astrophysics Data System (ADS)
Columbia Glacier is a grounded tidewater glacier located on the south coast of Alaska. It has lost half of its volume during 1957-2007, more rapidly after 1980. It is now split into two branches, known as Main/East and West branch due to the dramatic retreat of ~ 23 km and calving of iceberg from its terminus in past few decades. In Alaska, a majority of the mass loss from glaciers is due to rapid ice flow and calving icebergs into tidewater and lacustrine environments. In addition, submarine melting and change in the frontal position can accelerate the ice flow and calving rate. We use time series of high-resolution TanDEM-X stripmap satellite imagery during 2011-2013. The active image of the bistatic TanDEM-X acquisitions, acquired over 11 or 22 day repeat intervals, are utilized to derive surface velocity fields using SAR intensity offset tracking. Due to the short temporal baselines, the precise orbit control and the high-resolution of the data, the accuracies of the velocity products are high. We observe a pronounce seasonal signal in flow velocities close to the glacier front of East/Main branch of Columbia Glacier. Maximum values at the glacier front reach up to 14 m/day were recorded in May 2012 and 12 m/day in June 2013. Minimum velocities at the glacier front are generally observed in September and October with lowest values below 2 m/day in October 2012. Months in between those dates show corresponding increase or deceleration resulting a kind of sinusoidal annual course of the surface velocity at the glacier front. The seasonal signal is consistently decreasing with the distance from the glacier front. At a distance of 17.5 km from the ice front, velocities are reduced to 2 m/day and almost no seasonal variability can be observed. We attribute these temporal and spatial variability to changes in the basal hydrology and lubrification of the glacier bed. Closure of the basal drainage system in early winter leads to maximum speeds while during a fully developed basal drainage system speeds are at their minimum. We also analyze the variation in conjunction with the prevailing meteorological conditions as well as changes in calving front position in order to exclude other potential influencing factors. In a second step, we also exploit TanDEM-X data to generate various digital elevation models (DEMs) at different time steps. The multi-temporal DEMs are used to estimate the difference in surface elevation and respective ice thickness changes. All TanDEM-X DEMs are well tied with a SPOT reference DEM. Errors are estimated over ice free moraines and rocky areas. The quality of the TanDEM-X DEMs on snow and ice covered areas are further assessed by a comparison to laser scanning data from NASA Icebridge campaigns. The time wise closest TanDEM-X DEMs were compared to the Icebridge tracks from winter and summer surveys in order to judge errors resulting from the radar penetration of the x/band radar signal into snow, ice and firn. The average differences between laser scanning and TanDEM-X in August, 2011 and March, 2012 are observed to be 8.48 m and 14.35 m respectively. Retreat rates of the glacier front are derived manually by digitizing the terminus position. By combining the data sets of ice velocity, ice thickness and the retreat rates at different time steps, we estimate the seasonal variability of the ice discharge of Columbia Glacier.
Vijay, Saurabh; Braun, Matthias
Application of the inundation areaólake level rating curves constructed from the SRTM DEM to retrieving lake levels from satellite measured inundation areas
NASA Astrophysics Data System (ADS)
Remote sensing technology has great potential for measuring lake inundation areas and lake levels, and providing important lake water quantity and quality information which can be used for improving our understanding of climate change impacts on the global water cycle, and assessing the influence of the projected future climate change on the global water resources. One remote sensing approach is to estimate lake level from satellite measured inundation area based on the inundation areaólake level rating (IALLR) curves. However, this approach is not easy to implement because of a lack of data for constructing the IALLR curves. In this study, an innovative and robust approach to construct the IALLR curves from the digital elevation model (DEM) data collected during the Shuttle Radar Topography Mission (SRTM) was developed and tested. It was shown that the IALLR curves derived from the SRTM DEM data could be used to retrieve lake level from satellite measured inundation area. Applying the constructed IALLR curve to the estimated inundation areas from 16 Landsat Thematic Mapper (TM) images, 16 lake levels of Lake Champlain in Vermont were obtained. The root mean square error (RMSE) of the estimated lake levels compared to the observed water levels at the U.S. Geological Survey (USGS) gauging station (04294500) at Burlington, Vermont is about 0.12 m.
Pan, Feifei; Liao, Jingjuan; Li, Xinwu; Guo, Huadong
Uplift mechanism for a shallow-buried structure in liquefiable sand subjected to seismic load: centrifuge model test and DEM modeling
NASA Astrophysics Data System (ADS)
Based on a centrifuge model test and distinct element method (DEM), this study provides new insights into the uplift response of a shallow-buried structure and the liquefaction mechanism for saturated sand around the structure under seismic action. In the centrifuge test, a high-speed microscopic camera was installed in the structure model, by which the movements of particles around the structure were monitored. Then, a two-dimensional digital image processing technology was used to analyze the microstructure of saturated sand during the shaking event. Herein, a numerical simulation of the centrifuge experiment was conducted using a two-phase (solid and fluid) fully coupled distinct element code. This code incorporates a particle-fluid coupling model by means of a "fixed coarse-grid" fluid scheme in PFC3D (Particle Flow Code in Three Dimensions), with the modeling parameters partially calibrated based on earlier studies. The physical and numerical models both indicate the uplifts of the shallow-buried structure and the sharp rise in excess pore pressure. The corresponding micro-scale responses and explanations are provided. Overall, the uplift response of an underground structure and the occurrence of liquefaction in saturated sand are predicted successfully by DEM modeling. However, the dynamic responses during the shaking cannot be modeled accurately due to the restricted computer power.
Zhou, Jian; Wang, Zihan; Chen, Xiaoliang; Zhang, Jiao
Heterotype Mischbarkeit zwischen Wolframit- und Columbitgruppe
Zusammenfassung Bei der NNachpr¸fungder Niobatsysteme mit verbesserten Apparaturen wurde festgestellt, daþ sich MnNbO4, NiNbO4 und CoNbO44b als MnNb2O6, NiNb2O6 und CoNb2O6 erwiesen. Stabilit‰tsabsch‰tzungenergaben, daþ f¸r FeNbO4 das Rutilgitter bis zum Schmelzpunkt gegen das Wolframitgitter, f¸r TiO2 das Anatasgitter bis zum Schmelzpunkt gegen das Rutilgitter und f¸r FeNb2O6 wahrscheinlich das Rutilgitter gegen das Columbitgitter instabil sind.
Helmut Schrocke
Electrocatalytic mechanism and kinetics of SOMs oxidation on ordered PtPb and PtBi intermetallic compounds: DEMS and FTIRS study.
The electrocatalytic activities and mechanisms of PtPb and PtBi ordered intermetallic phases towards formic acid, formaldehyde and methanol oxidation have been studied by DEMS and FTIRS, and the results compared to those for a pure polycrystalline platinum electrode. While PtPb exhibits an enhanced electrocatalytic activity for the oxidation of all three organic molecules when compared to a Pt electrode, PtBi exhibits an enhanced catalytic activity towards formic acid and formaldehyde oxidation, but not methanol. FTIRS data indicate that adsorbed CO does not form on PtPb or PtBi intermetallic compounds during the oxidation of formic acid, formaldehyde and methanol, and therefore their oxidation on both PtPb and PtBi intermetallic compounds proceeds via a non-CO(ads) pathway. Quantitative DEMS measurements indicate that only CO(2) was detected as a final product during formic acid oxidation on Pt, PtPb and PtBi electrodes. At a smooth polycrystalline platinum electrode, the oxidation of formaldehyde and methanol produces mainly intermediates (formaldehyde and formic acid), while CO(2) is a minor product. In contrast, CO(2) is the major product for formaldehyde and methanol oxidation at a PtPb electrode. The high current efficiency of CO(2) formation for methanol and formaldehyde oxidation at a PtPb electrode can be ascribed to the complete dehydrogenation of formaldehyde and formic acid due to electronic effects. The low onset potential, high current density and high CO(2) yield make PtPb one of the most promising electrocatalysts for fuel cell applications using small organic molecules as fuels. PMID:18563235
Wang, Hongsen; Alden, Laif; Disalvo, F J; AbruÒa, HÈctor D
Geographic Information Network of Alaska: Real-Time Synoptic Satellite Data for Alaska and the High Arctic, Best Available DEMs, and Highest Available Resolution Imagery for Alaska
NASA Astrophysics Data System (ADS)
In support of the International Polar Year, the Geographic Information Network of Alaska (GINA) intends to make available to researchers three important Arctic data sets. The first is near-real-time synoptic scale data from GINA and NOAA/NESDIS satellite ground stations. GINA operates ground stations that receive direct readout from the AVHRR (1.1-km per pixel resolution) and MODIS (250- to 1000-meter) sensors carried on NOAA and NASA satellites. GINA works in partnership with NOAA/NESDIS's Fairbanks Command and Data Acquisition Station (FCDAS) to distribute real-time data captured by FCDAS facilities in Fairbanks and Barrow, Alaska. AVHRR and Feng Yun 1D (1.1-km) sensors are captured in Fairbanks by FCDAS and distributed by GINA. AVHRR data is captured by FCDAS in Barrow and distributed by GINA. Due to its high latitude, the station mask of the Barrow station extends well beyond the Pole, showing the status in real-time of Arctic basin cloud and sea ice conditions. Second, digital elevation models (DEM) for Alaska vary greatly in quality and availability. The best available DEMs for Alaska will be combined and served through a GINA gateway. Third, the best available imagery for more than three quarters of Alaska is 15-meter pan-sharpened Landsat data. Less than a quarter of the state is covered by 5-meter or better data. The best available imagery for Alaska will be combined and served through a GINA gateway. In accordance with the IPY Subcommittee on Data Policy and Management recommendations, all data will be made available via Open Geospatial Consortium protocols, including Web Mapping, Feature, and Coverage Services. Data will also be made available for download in georeferenced formats such as GeoTIFF, MrSID, or GRID. Metadata will be available though the National Spatial Data Infrastructure via Z39.50 GEO protocols and through evolving web-based metadata standards.
Heinrichs, T. A.; Sharpton, V. L.; Engle, K. E.; Ledlow, L. L.; Seman, L. E.
Les Èchanges industriels entre la France et les pays d'Europe centrale et orientale : premiËres tendances de la spÈcialisation
[ger] Der Industriehandel zwischen Frankreich und den mittel- und osteuropaischen L'ndern: erste Spezialisierungstendenzen . Der Austausch zwischen Frankreich und den mittel- und sischen Exporte von Investitionsg˘tem und High-Tech- osteurop'ischen L'ndern hat seit dem Zusammenbruch Erzeugnissen (Elektronikgerýte, Prazisionsinstrumente) des Rats fur Gegenseitige Wirtschaftshilfe (COMECON) gefÙrdert. im Jahre 1990 stark zugenommen, wenn auch seine HandelstrÙme mit diesen L'ndern betragsm'Big noch . recht
BÈatrice Colin-SÈdillot
Die Wirkung von Work-Life Balance Initiativen auf das Mitarbeitercommitment: Eine empirische Untersuchung in der Unternehmensberatungsbranche (The Impact of Corporate Work-life Balance Initiatives on Employee Commitment: An Empirical Investigation in the German Consultancy Sector)
Der vorliegende Beitrag untersucht die Wirkung von unternehmerischen Work-Life Balance Initiativen fuer die emotionale Bindung der Mitarbeiter zum Unternehmen, d. h. das organisationale Commitment von Mitarbeitern im Kontext der Unternehmensberatung. Dazu wurde eine Untersuchung mit insgesamt 275 Unternehmensberaterinnen und -beratern durchgefuehrt. Die Datenanalyse erfolgte anhand eines PLS-Strukturgleichungsmodells (Partial-Least-Squares-Ansatz). Die Ergebnisse weisen darauf hin, dass auch in Beratungsorganisationen ein Zusammenhang zwischen
Stephan Kaiser; Max Ringlstetter; Cornelia U. Reindl; Martin L. Stolz
Hypertriglyceridemiaówhy, when and how should it be treated?
Der Zusammenhang zwischen Serum-Triglyzerid-Konzentrationen und kardiovaskul‰ren Erkrankungen ist trotz vier Jahrzehnten Forschung bislang ungekl‰rt geblieben. Die meisten Arbeiten deuten auf eine Rolle der Triglyzeride als unabh‰ngiger kardiovaskul‰rer Risikofaktor hin. Allerdings existieren zur Zeit keine Richtlinien, die bestimmte Triglyzerid-Werte zur Pr‰vention kardiovaskul‰ren Erkrankungen empfehlen. Derzeit ist das Augenmerk auf die Verminderung des globalen kardiovaskul‰ren Risikos durch die Optimierung der LDL-Cholesterin-Konzentration gerichtet.
I. Gouni-Berthold; W. Krone
Investigating the definition of flood maps using a 2D hydraulic routing model forced by a DEM-based fully continuous rainfall-runoff algorithm
NASA Astrophysics Data System (ADS)
Ongoing efforts of remote sensing technologies to provide more accurate digital elevation models (DEMs) at the global scale are supporting the use of terrain analysis and hydrologic and hydraulic modelling algorithms for flood mapping in ungauged basins. In this work we implement a fully continuous hydrologic-hydraulic model feeded by a rainfall synthetic time series for providing river hydrographs that are routed along the channel using a bidimensional hydraulic model for the detailed physically-based characterization of the inundation process. In this way the whole physical process is represented, from the net rainfall to the flow time series, avoiding any conceptual sub-method (design hyetograph and hydrograph) commonly needed to apply standard flood modelling and mapping procedures. Nevertheless, the floodplain information is no longer deterministic as the result of the evaluation of the impact on the river valley of a single design hydrologic scenario (event-based approach,EBA), but the final result is composed of a combination of data derived by the application of a fully-continuous approach (FCA). Indeed FCA provides a flow depth time series for each single cell of the inundated domain. The final flood map should be, thus, the result of a proper analysis of this dataset in statistical, qualitative and quantitative terms. Otherwise this would lead to an undefined flooding scenario that could be useless for flood risk management and decision making in urban plans.
Nardi, Fernando; Petroselli, Andrea; Grimaldi, Salvatore
Numerical simulation of the transport and deposition behaviour of particles on filter fibres using Euler-Lagrange Method and coupling of CFD and DEM
NASA Astrophysics Data System (ADS)
The aim of this investigation is the development of a simulation method which accounts for the transport behaviour of particles in the vicinity of a single filter fibre and describes the particle deposition on the fibre element correctly. Two coupling schemes are used to connect the CFD software Fluentô with the DEM software EDEM, the Euler-Lagrange as well as the Euler-Euler coupling. In this study both methods will be compared to each other and with results where the motion and reallocation of dendrite structures is neglected. Furthermore, the numerical results are compared to experimental data. The investigation is aimed for the consideration of spherical particles but the method can be expanded easily to calculate the transport behaviour of non spherical particles. The motion and reallocation of dendrite structures on a filter fibre which are built-up from deposited particles is analysed. To determine the transport behaviour of particles in the fluid flow in respect of their finite size of the Euler-Euler coupling method is used which is accounted for the particles in the fluid domain by the solid volume fraction. The results indicate the great influence of the reallocation to the dendrite formation and on the separation efficiency.
Schilling, M.; Sch¸tz, S.; Piesche, M.
Untersuchungen an Hochdruckrelikten im zentralen Menderes Massiv, W T¸rkei
NASA Astrophysics Data System (ADS)
Das Menderes Massiv im Westen der T¸rkei stellt eine groe Kulmination metamorpher Gesteine dar. Das Untersuchungsgebiet ist im Zentralen Menderes Massiv (÷demis Submassiv) gelegen, das von den beiden aktiven Gr‰ben, dem Gediz Graben im Norden und dem B¸y¸k Menderes Graben im S¸den begrenzt wird. Die Untersuchungen der Eklogit Relikte im zentralen Menderes Massiv haben ergeben, dass sich im Menderes Massiv Hochdruckrelikte in unterschiedlichen tektonischen Positionen befinden. Zum einen existieren Eklogit-Blˆcke in der obersten Einheit (Selcuk Einheit) des zentralen Menderes Massivs und zum anderen Hochdruck-Relikte in der strukturell mittleren Birgi - Tire Decke. Die Granate der quarzfreien Eklogit-Blˆcke weisen groe ƒhnlichkeiten mit denen der HP/LT Gesteine von Sifnos und Syros auf. Die Entwicklung der Eklogit-Blˆcke in der Olistostrom-Einheit l‰sst sich jedoch nicht mit den Eklogit Relikten in der strukturell mittleren Birgi Tire Decke vergleichen. F¸r die Eklogit-Relikte in der Birgi Tire Decke wurde eine polymetamorphe Entwicklung mithilfe petrologischer Untersuchungen und chemischen und Pb-Pb Datierungen herausgearbeitet. Die Eklogit Relikte gehˆren zu einem metamorphen Teilpfad, der durch eine Amphibolitfazies 1 - Hochdruck - Amphibolitfazies 2/Granulitfazies charakterisiert ist. Der Endpunkt dieses Teilpfades ist mit Temperaturen zwischen 700 und 750 ∞C und Dr¸cken von 1.2 - 1.4 GPa belegt. F¸r diese Bedingungen konnte ein minimales Alter von 520 Ma durch chemische Datierungen an Monaziten einer Augengneisprobe und Pb-Pb Datierungen an Zirkonen einer Augengneis- und Metagabbroprobe bestimmt werden. Dieser amphibolit/granulitfazieller Endpunkt wird mit den Granitintrusionen des zentralen und s¸dlichen Menderes Massiv korreliert, die in einem Zeitraum zwischen 520 Ma bis 550 Ma stattfanden. Sowohl die Amphibolitfazies 1 als auch das Hochdruckereignis werden der Panafrikanischen Orogenese zugeordnet. F¸r die Hochdruckbedingungen wurden maximale Temperaturen zwischen 680∞C und 720∞C und bei einem Druck von 2.2 GPa bestimmt. In den untersuchten Metasedimenten konnte eine prograde metamorphe Entwicklung abgeleitet werden, die amphibolitfazielle Bedingungen von 660∞C bei 0.6 GPa erreichte. Das Metamorphosealter dieser Metasedimente konnte mit < 100 Ma mittels chemischer Mikrosondendatierung bestimmt werden. Die in den Metasedimenten herausgearbeiteten Druck- und Temperaturbedingungen wurden ebenfalls in den metabasischen Gesteinen bestimmt. Diese Ergebnisse werden als Krustenstapelung der metabasischen Gesteine, Augengneise und Metasedimente interpretiert, die mit der alpinen Orogenese im Zusammenhang stehen. Durch die Ergebnisse dieser Arbeit l‰sst sich die Birgi-Tire Decke im zentralen Menderes Massiv genauer charakterisieren. Sie besteht aus Metasedimenten, pelitischen Gneisen, Augengneisen und metabasichen Gesteinen. Die Gneise (pelitische und Augengneise) und die metabasischen Gesteine stellen panafrikanische Relikte dar, die einen amphibolit- eklogit- amphibolit/granulitfaziellen Metamorphosepfad gespeichert haben. Die amphibolit- bis granulitfazielle Metamorphose h‰ngt mit den Granitintrusionen zusammen und fand in einem Zeitraum zwischen 520 - 550 Ma statt. Groe Teile der Metasedimente der Birgi Tire Decke haben jedoch nur eine alpine metamorphe Entwicklung durchlaufen, wo sie unter amphibolitfazielle Bedingungen Krustentiefen erreichten, bei denen sie mit den panafrikanischen Relikten zusammen gestapelt wurden und eine gemeinsame Exhumierung erfahren haben. The Menderes Massif in western Turkey is a large culmination of metamorphic rocks. The investigation area is bounded by two active graben systems, the Gediz Graben in the north and the B¸y¸k Menderes Graben in the south. One result of our investigation in the central Menderes Massif is the occurrence of eclogite relicts in different tectonic positions. On one hand eclogite blocks exist in the structurally highest nappe (Selcuk unit) of the central Menderes Massif, and on the other hand the high pressure relicts exist in the struc
Warkus, Friederike C.
Comparison and validation of the recent freely available ASTER-GDEM ver1, SRTM ver4.1 and GEODATA DEM9S ver3 digital elevation models over Australia
This study investigates the quality (in terms of elevation accuracy and systematic errors) of three recent publicly available elevation model datasets over Australia: (i) the 9 arc second national GEODATA DEM-9S ver3 from Geoscience Australia and the Australian National University; (ii) the 3 arc second SRTM ver4.1 from CGIAR-CSI; and (iii) the 1 arc second ASTER-GDEM ver1 from NASA\\/METI. The
C. Hirt; M. S. Filmer; W. E. Featherstone
Evolution of Vein Networks and Structural Styles of Fracture-Vein Interaction: Insight into the Crack-Seal Process from 3D-DEM Modelling.
NASA Astrophysics Data System (ADS)
Observations from natural vein systems suggest that preexisting veins can strongly influence fracture localization and propagation in a rock even in cases where the orientation of the stress field is incompatible with the orientation of the new fracture. We employ 3D discrete element simulations to model the evolution and fracture dynamics of crack seal systems. A sensitivity study has shown that variation of the misorientation angle between the vein and fracture as well as the strength ratio between host rock and vein material results in several "structural styles" of fracture-vein interactions: Veins which are weaker than the host rock tend to localize fracturing into the vein, even at high misorientation angles. Veins stronger than the host rock cause deflection of the fracture tip along the vein- host rock interface. In some cases fractures are arrested at the interface from weak to stronger material. When fractures are propagating from a stronger to a weaker material, macroscopic bifurcation can occur. Complex interactions are favored by low angle between the vein and the fracture, and by high strength contrast. We propose that these structural styles form the basis for criteria to recognize strength contrasts and stress of crack seal systems in nature. The influence of fracture-vein interactions on the texture and geometry of crack seal veins and vein networks is studied in multiphase 3D DEM Simulations. After fracturing of the model in layer-parallel extension, open fractures are filled with new material and the cohesion of the model is reestablished before it is fractured again. The crack-seal and crack-jump mechanisms ensue naturally from this workflow as a result of the strength of the vein material relative to the host rock. The models enable the study of more complex crack seal vein networks that evolve under more complex cyclic loading conditions with varying orientation of the principal stresses.
Virgo, Simon; Abe, Steffen; Urai, Janos
Failure and frictional sliding envelopes in three-dimensional stress space: Insights from Distinct Element Method (DEM) models and implications for the brittle-ductile transition of rock
NASA Astrophysics Data System (ADS)
Rocks deformed at low confining pressure are brittle, meaning that after peak stress the strength decreases to a residual value determined by frictional sliding. The difference between the peak and residual value is the stress drop. At high confining pressure, however, no stress drop occurs. The transition pressure at which no loss in strength occurs is a possible definition of the brittle-ductile transition. The Distinct Element Method (DEM) is used to illustrate how this type of brittle-ductile transition emerges from a simple model in which rock is idealised as an assemblage of cemented spherical unbreakable grains. These bonded particle models are subjected to loading under constant mean stress and stress ratio conditions using distortional periodic space, which eliminates possible boundary effects arising from the usage of rigid loading platens. Systematic variation of both mean stress and stress ratio allowed determination of the complete three dimensional yield, peak stress and residual strength envelopes. The models suggest that the brittle-ductile transition is a mean stress and stress ratio dependent space curve, which cannot be adequately described by commonly used failure criteria (e.g., Mohr-Coulomb, Drucker-Prager). The model peak strength data exhibit an intermediate principal stress dependency which is, at least qualitatively, similar to that observed for natural rocks deformed under polyaxial laboratory conditions. Comparison of failure envelopes determined for bonded particle models with and without bond shear failure suggests that the non-linear pressure dependence of strength (concave failure envelopes) is, at high mean stress, the result of microscopic shear failure, a result consistent with earlier two-dimensional numerical multiple-crack simulations [D. A. Lockner & T. R. Madden, JGR, Vol. 96, No. B12, 1991]. Our results may have implications for a wide range of geophysical research areas, including the strength of the crust, the seismogenic zone and slip-tendency analysis.
Schˆpfer, Martin; Childs, Conrad; Manzocchi, Tom
Anti-nuclear liberals and the bomb: A comparative history of Kampf dem Atomtod and the Committee for a Sane Nuclear Policy, 1957-1963
The premises of Kampf dem Atomtod (KdA) and Citizens for a Sane Nuclear Policy (SANE) were based on nineteenth century traditions of liberal peace advocacy. Both groups gained substantial public support for their goals to prevent the nuclear armament of the Bundeswehr and to stop nuclear testing. Both organizations won well-educated middle-class and mostly white supporter. The dissertation examines the role of women: whether housewife or doctor, women stressed their special concerns as mothers. Both KdA and SANE had troubled relations with the labor movement. Their leaders hoped to gain government leaders' respect by winning a respectable, non-Communist constituency and claiming their goals were reasonable ones. Government officials attacked KdA and SANE as dupes of Moscow. Many supporters left the organizations because of their strict anti-Communism. Local groups accused their leaders of lacking initative. KdA and SANE's leaders wasted time and energy rehashing issues and postponing decisions. After a period of providing initiatives and ideas local committees disintegrated. Both organizations considered education their paramount goal but their arguments primarily reached the converted, who often preferred more political action. KdA and SANE's leaders instead chose to support respectable projects based on humanitarian ideals. Since these projects offered little in the way of concrete action agendas, supporters defected to more active organizations or slipped into apathy. Neither organization achieved its national goals. Both governments generally denied them access to the policymaking process, ignored them as irrelavant, or attacked them as Communist sympathizers. While SANE and KdA were heard by those concerned by nuclear policy, and while members of SANE's National Board did help muster support for the Partial Test Ban Treaty, both organizations failed to make liberal peace values productive in the nuclear decisionmaking process.
Thiede, B.
Modelling comminution devices using DEM
Particle size reduction, or milling, is an essential component of mineral processing and is important in other industry sectors. This needs to be done as efficiently as possible, maximizing mill throughput while minimizing operating costs. Such milling processes typically use only 1-5 per cent of the supplied energy for particle breakage, which leaves room for improvement. In discrete element modelling
Paul Cleary
Der Windows UDK 4.3 auf Basis der SOAP Technologie
Der Umweltdatenkatalog (UDK) hat sich zum Quasi-Standard f¸r Metadaten im Um- weltbereich in Deutschland und ÷sterreich entwickelt. Seit 1998 ist der UDK in der Version 4 im Produktionsbetrieb. Die Erfassungskomponente, der Windows-UDK, wird in der Version 4.3 zu einer Drei-Schichten-Architektur ausgebaut, wobei die Kommunikation zwischen dem UDK-Client und dem UDK-Server auf dem SOAP- Protokoll basiert.
Fred Kruse; Marco Eichler
Long-term erosion rates of Neogene to Quaternary volcanoes of the Altiplano-Puna plateau, Central Andes: an SRTM DEM study
NASA Astrophysics Data System (ADS)
Neogene to Quaternary volcanism of the Central Andes offers a unique opportunity to study long-term erosion of stratovolcanoes. On the basis of SRTM DEM data, we invesigated 35 stratovolcanoes of the 3,800-4,000 m high, arid-hyperarid Altiplano-Puna plateau (from 14oS, 64oW to 27oS, 74oW). The volcanoes have been selected on geomorphological criteria such as (1) a single, "mature" cone-shape with considerable size, (2) location on a relatively flat basement, (3) no overlap with other volcanic centres, and (4) lack of calderas or sector collapse scars. Volcanoes of various age (Mid-Miocene to Quaternary based on sporadic radiometric dates) and various degradation stage have been included in order to infer long-term erosion rates. The method we follow is to quantitatively compare the existing topography with the present-day active volcanoes, e.g. Parinacota (Northern Chile). By applying an advanced computational method, we fit the relief of the undissected, almost perfect reference cone over the degraded volcanic edifice. This way, we can precisely calculate (a) the degree of denudation by difference between the computed initial volume from the fit and the observed volume, and (b) for volcanoes with radiometric age constraint the erosion rate (m/Ma) as the areal mean of denudation divided by age. Our results show that (a) the studied volcanoes are degraded to various extent up to ~40% (denudation ratio) of the paleo-volume. In accordance, their relative height which is progressively lower shows a moderately good correlation with denudation (r2 = 0.70). Using the available age constraints, we obtained a stronger correlation between age and denudation (r2 = 0.82 for all volcanoes, and r2 = 0.95 without the southernmost hyperarid and northernmost semihumid volcanoes). (b) Therefore, calculating erosion rates gives highly reliable results. The youngest volcanoes (e.g. Ollag¸e, Tacora) shows 50-100 m/Ma erosion rates which fits well to the initially rapid degradation of active volcanic edifices without vegetation cover. Long-term erosion rates of the Pliocene to Miocene volcanoes, in constrast, are much lower and more uniform (7-17 m/Ma), in agreement with other, similarly low erosion rates obtained by other methods (e.g. cosmogenic nuclides) for the Altiplano-Puna highland. Our rates show the smallest values for the hyperarid Puna and the southern Altiplano (e.g. Maricunga volcano), and the greatest values for the semihumid Southern Peru (e.g. Ccarhuaraso, Jatunpuco volcanoes). Moreover, using the very good age vs denudation correlation as a geomorphological dating tool, we are able to estimate ages for undated volcanoes of the Central Andes or for other regions under similar climate conditions.
Kar·tson, D·vid; Telbisz, Tam·s.; Wˆrner, Gerhard
An algorithm for generalizing topography to grids while preserving subscale morphologic characteristicsócreating a glacier bed DEM for Jakobshavn trough as low-resolution input for dynamic ice-sheet models
NASA Astrophysics Data System (ADS)
The objective of this paper is to derive an algorithm for preserving important subscale morphologic characteristics at grids of lower-resolution, in particular for linear features such as canyons and ridge lines. The development of such an algorithm is necessitated by applications that require reduced spatial resolution, as is common in cartographic generalization, GIS applications, and geophysical modeling. Since any algorithm that results in weighted averages, including optimum interpolation and ordinary kriging, cannot reproduce correct depths, a new algorithm is designed based on principles of mathematical morphology. The algorithm described here is applied to derive a subglacial bed of the Greenland Ice Sheet that includes the trough of Jakobshavn IsbrÊ as a continuous canyon at correct depth in a low-resolution (5-km) digital elevation model (DEM). Data from recent airborne radar measurements of the elevation of the subglacial bed as part of the CReSIS project are utilized. The morphologic algorithm is designed with geophysical ice-sheet modeling in mind, in the following context. Currently occurring changes in the Earth's climate and the cryosphere cause changes in sea level, and the societal relevance of these natural processes motivates estimation of maximal sea-level rise in the medium-term future. The fast-moving outlet glaciers are more sensitive to climatic change than other parts of the Greenland ice sheet. Jakobshavn Isbrae, the fastest-moving ice stream in Greenland, follows a subglacial geologic trough. Since the existence of the trough causes the acceleration of the slow-moving inland ice in the Jakobshavn region and the formation of the ice stream, correct representation of the trough in a DEM is essential to model changes in the dynamics of the ice sheet and resultant sea-level predictions, even if current ice-sheet models can typically be run only at 5-km resolution. The DEM resultant from this study helps to bridge the conceptual gap between data analysis and geophysical modeling approaches. It is available as SeaRISE Greenland bed data set dev1.2 at http://websrv.cs.umt.edu/isis/index.php/SeaRISE_Assessment.
Herzfeld, Ute C.; Wallin, Bruce F.; Leuschen, Carlton J.; Plummer, Joel
Die Verteilung des Alkohols im Blut
1.Es wird ¸ber verschiedene Versuchsreihen berichtet, die daf¸r sprechen, daþ sich der Alkohol zwischen Blutkˆrperchen und Plasma bzw. Serum entsprechend dem jeweiligen Wassergehalt verteilt.2.Bezeichnet man das Alkoholkonzentrationsverh‰ltnis zwischen Serum und Vollblut alsqu, das Wasserkonzentrationsverh‰ltnis alsquw, so gilt:qu = quw.3.Auf die praktische Bedeutung der Untersuchungsergebnisse wird hingewiesen: Eine Berechnung der BAK aus der Serum-Alkoholkonzentration sollte (wegen der selbst bei der gleichen
O. Gr¸ner
New insights into palaeoglaciological processes in northeastern Germany by analysis of a LiDAR DEM: using high-resolution elevation data to reassess the geomorphology of the Barnim till plain
NASA Astrophysics Data System (ADS)
We used airborne LiDAR DEM data to reassess the current state of research of an intensively studied "classical" glacial landscape, the Barnim till plain northeast of Berlin. To gain new insights into palaeoglaciological dynamics, we examined a high-resolution DEM for geomorphic features that either prove or negate previous research. The study area was last glaciated in the Weichselian, and its landforms are associated with the W1B- (Brandenburg phase) and W1F-advances (Frankfurt phase), except for the eastern Barnim where a push moraine complex was compressed during the Saalian. The course and the timing of the W1F ice marginal position, which is assigned to the Barnim area, are contradictorily discussed in literature. Hence, landscape analysis with a high resolution DEM appears to be a promising tool. The LiDAR data used here has a ground resolution of 1 m and a height accuracy of 30 - 50 cm. In an ArcGIS 10 environment a database was created that contains spatial information about the study area collected from different sources. These include digitized geological and geomorphological maps as well as geochronological data from different authors. Owing to the size of the Barnim (~1900 km≤), three subsets with a size of 10 x 15 km were selected for advanced analysis (western, middle and eastern Barnim). Each subset represents one of the most characteristic landscapes of the study area. For each subset we performed a qualitative analysis of landscape features. The results were compared with each other and connected to the whole Barnim area as well as the current state of research. The most remarkable discovery was made in the middle Barnim. Here we identified a set of consecutive arcuate ridges. Their widths (NE-SW) are around 1000 - 1500 m, and their lengths are around 10 - 15 km; they rise some 10 m above their surroundings. According to geological maps and our own fieldwork, they are covered by till. A sandy or peaty substrate lies between the ridges. The inner sides of the ridges are northeast-oriented and rather steep, and the outer sides face southwest with a dip at a flatter angle. The ridges are incised radially. Their lobe-like form and the distribution of the substrates suggest a glacial origin. We propose a genetic model of recessional moraines that were deposited in front of an oscillating glacier lobe; however, other possibilities are also discussed. Similar forms were recently found around the ice margin of piedmont glaciers, e.g. the Malaspina glacier in southwest Alaska. The timing of their formation still has to be investigated. Fine gravel analyses from other studies imply that they consist of a till that can probably be associated with a Weichselian ice advance. Understanding the genesis of the newly described ridges may be a key to solve the contradictory "Frankfurt phase problem" in terms of glaciodynamics and stratigraphy Our study shows that even in intensively researched areas high-resolution DEM data can reveal landscape features that shed a new light on landscape genesis. Nevertheless, further fieldwork and geochronological data are necessary to obtain a complete picture of palaeoglaciological processes in the northeastern German lowland.
Hardt, Jacob; Bˆse, Margot; Hebenstreit, Robert; L¸thgens, Christopher
The use of DEM analysis for structural characterization of landslide-prone areas in crystalline rock slopes using GIS-based techniques. The case of the Matter Valley, Switzerland
NASA Astrophysics Data System (ADS)
Mountainous regions influenced by glacial processes are often prone to slope instabilities. One reason for this relationship is their characteristic morphology (high relief and steep slopes) and the surface processes associated with glacial advance and retreat. In the Matter Valley, Switzerland these factors interact with brittle-ductile faults and joint sets and induce rock slope failures at multiple scales, including the 3x107 m3 Randa and the 1x105 m3 Medji events. The general lithological and tectonic disposition in the study area is quite homogeneous, while the local fracture systems and their characteristics vary spatially. These features provide the opportunity to evaluate potential relationships between the local fracture systems and the potential failure modes they develop with the observed slope morphology and its state of stability. In order to investigate this hypothesis the fracture pattern of the area was analyzed using a new combination of data collected from the field and data extracted from an aerial-based LIDAR high resolution DEM (SWISSTOPO, 2m pixel resolution). This is possible for the area because the fracture pattern has been observed to have a strong influence in the morphology of the slopes. To identify slope faces controlled by structures a 3D shaded relief map of the area was produced. A 3D shaded relief map is a color-coded image based on HSV color composition showing changes in color according with the changes on slope orientation (dip and dip direction). A careful selection of the planes used for the analysis was carried out taking in consideration that not all values in the 3D shaded relief image represent fracture orientations; this is due to multiple factors such as cell size of the DEM, presence of land cover (soil), and presence of overhanging blocks. Selection of cells was done using 3D visualizations (an orthophoto mosaic created with aerial photographs acquired in 2005 was used as the top-most layer) and photographs of the slopes taken from different angles during the field data collection campaigns. The orientation values extracted from the DEM analysis needed an areal value correction. This correction is based on the fact that steep slopes are represented for a fewer number of cells than gentle slopes. A total of more than 120000 fracture orientations were obtained from this analysis and displayed in a total of 45 stereoplots. Field data and DEM derived data were compared each other and with data of previous works in order to assess the reliability of the method. As a product of the analysis the area was divided in two main structural domains based on the spatial distribution of the fracture patterns. These domains have shown a clear connection with the frequency of instabilities and therefore with the differences in morphology of the slopes.
Yugsi Molina, F. X.; Loew, S.; Button, E.
Abfallwirtschaft zwischen Ðberkapazit‰ten und Entsorgungsenpass - Eine kritische Bestandsaufnahme
At present, the utilization of waste products in Germany is characterized by the enforcement of rigorous environmental standards (pre-treatment of waste, sealing of dumps) and following from that a temporary capacity problem regarding the disposal of pre-treated household refuse and the incineration of calorie intensive trade refuse. The privatization of commercial waste for utilization under the Waste Management Law of
Fritz Rahmeyer
Ðber die Geruchsspur von Lasius fuliginosus zwischen Nest und Futterquelle
Summary In this study it was found that the chemical trail laid by workers of the ant speciesLasius fuliginosus between their nest and a food source, is always laid in the direction food to nest. It was also found that this trail can be artificially created by dissolving the contents of the ant's hind-gut or stomach in water, and then
W. Hangartner; St. Bernstein
Beziehungen zwischen Fettkˆrper, Oenocyten und Wachsdr¸senentwicklung bei Apis mellifica L
1.The structure of cytoplasm and nuclei of larval oenocytes indicates glandular function and the formation of secretory substances. Maximal oenocyte activity was determined through cell measurements. The maximum was found in young larvae. Nucleus and cytoplasm show parallel growth and shrinkage, but there was no observable connection between oenocyte activity and moulting.2.The development of both the corpora allata and of
Brigitte Boehm
Variability of structures in German intensive care units ñ a representative, nationwide analysis
\\u000a ZusammenfassungÝÝHINTERGRUND: Strukturen in der Intensivmedizin sind charakterisiert durch die vorhandenen humanen und materiellen Ressourcen,\\u000a der Organisation und dem Management. Ein variabler Zusammenhang mit Prozessen und Ergebnissen besteht. Die Strukturen deutscher\\u000a Intensivstationen (ICU) wurden auf der Grundlage einer repr‰sentativen Querschnittsstudie evaluiert. METHODEN: Die Erhebung\\u000a wurde vom deutschen Kompetenznetz Sepsis (SepNet) durchgef¸hrt. Alle Daten wurden im Rahmen einer prospektiven, repr‰sentativen\\u000a Querschnittsstudie deutscher
J¸rgen Graf; Andrea Reinhold; Frank M. Brunkhorst; Max Ragaller; Konrad Reinhart; Markus Loeffler; Christoph Engel
\\u000a Zusammenfassung\\u000a EinleitungÝÝZiel der Studie war es, einen Zusammenhang zwischen den funktioneilen Ergebnissen nach photodynamischer Therapie (PDT) und\\u000a der F‰higkeit unserer Patienten, sich im t‰glichen Leben zurechtzufinden, herzustellen. Vier Wiener Spit‰ler (Hanuschkrankenhaus,\\u000a Krankenanstalt Rudolfstiftung, Krankenhaus Lainz und Sozialmedizinisches Zentrum Ost) beteiligten sich an dieser Studie. Die\\u000a Ergebnisse nach 1 Jahr werden pr‰sentiert.\\u000a \\u000a \\u000a \\u000a Patienten und MethodeÝÝAugen mit vorwiegend klassischer choroidaler Neovaskularisation (CNV)
I. Krebs; S. Binder; U. Stolba; D. Sonderhof; W. Brannath; A. Goll
Shape-selected nanocrystals for in situ spectro-electrochemistry studies on structurally well defined surfaces under controlled electrolyte transport: A combined in situ ATR-FTIR/online DEMS investigation of CO electrooxidation on Pt
Summary The suitability and potential of shape selected nanocrystals for in situ spectro-electrochemical and in particular spectro-electrocatalytic studies on structurally well defined electrodes under enforced and controlled electrolyte mass transport will be demonstrated, using Pt nanocrystals prepared by colloidal synthesis procedures and a flow cell set-up allowing simultaneous measurements of the Faradaic current, FTIR spectroscopy of adsorbed reaction intermediates and side products in an attenuated total reflection configuration (ATR-FTIRS) and differential electrochemical mass spectrometry (DEMS) measurements of volatile reaction products. Batches of shape-selected Pt nanocrystals with different shapes and hence different surface structures were prepared and structurally characterized by transmission electron microscopy (TEM) and electrochemical methods. The potential for in situ spectro-electrocatalytic studies is illustrated for COad oxidation on Pt nanocrystal surfaces, where we could separate contributions from two processes occurring simultaneously, oxidative COad removal and re-adsorption of (bi)sulfate anions, and reveal a distinct structure sensitivity in these processes and also in the structural implications of (bi)sulfate re-adsorption on the CO adlayer.
Jusys, Zenonas; Behm, R Jurgen
Selbstoptimierende Produktionssysteme
\\u000a Einer der zentralen Erfolgsfaktoren f¸r die Produktion in Hochlohnl‰ndern liegt in der Auflˆsung des Konflikts, der mit dem\\u000a Begriff der Planungswirtschaftlichkeit umschrieben werden kann. Die Planungswirtschaftlichkeit beschreibt das Verh‰ltnis aus\\u000a Planungsaufw‰nden und dem durch diese Aufw‰nde generierten Nutzen. Aus Sicht einer erfolgreichen Unternehmensf¸hrung besteht\\u000a die Herausforderung bislang darin, dynamisch den besten Weg zwischen einer detaillierten Planung und der unmittelbaren Gestaltung
Thomas Auerbach; Fabian Bauhoff; Marion Beckers; Daniel Behnen; Christian Brecher; Tobias Brosze; Guido Buchholz; Christian B¸scher; Burkhard Corves; Urs Eppelt; Martin Esser; Daniel Ewert; Kamil Fayzullin; Reinhard Freudenberg; Peter Fritz; Sascha Fuchs; Yves-Simon Gloy; Thomas Gries; Sebastian Haag; Eckart Hauck; Werner Herfs; Niklas Hering; Mathias H¸sing; Mario Isermann; Markus Janssen; Sabina Jeschke; Bernhard Kausch; Tobias Kempf; Fritz Klocke; Stephan Kratz; Sinem Kuz; Peter Loosen; Juliane Lose; Adam Malik; Marcel Ph. Mayer; Walter Michaeli; Thomas Molitor; Rainer M¸ller; Simon M¸ller; Barbara Odenthal; Alberto Pavim; Dirk Petring; Reinhard Poprawe; Till Potente; Nicolas Pyschny; Uwe Reisgen; Axel Reþmann; Martin Riedel; Heiko Schenuit; Daniel Schilberg; Christopher M. Schlick; Robert Schmitt; G¸nther Schuh; Wolfgang Schulz; Maik Sch¸rmeyer; Jens Sch¸ttler; Ulrich Thombansen; Draûen Veselovac; Matthias Vette; Carsten Wagels; Konrad Willms; Matthis Laass; Simone Runge
Unf‰lle mit Schienenfahrzeugen
NASA Astrophysics Data System (ADS)
Auf einer viel befahrenen Kreuzung ereignete sich in der Winterzeit und gegen Mitternacht eine Kollision zwischen einer Straþenbahn (roter Pfeil) und einem Polizeifahrzeug (blauer Pfeil). Die Straþenbahn hat als schienengebundenes Fahrzeug gegen¸ber dem sonstigen Verkehr ein Vorrecht. Das Polizeifahrzeug war auf einer Einsatzfahrt zu einem Wohnungsbrand und hatte insoweit auch ein Vorrecht, da unstreitig Blaulicht und Signalhorn eingeschaltet waren. Das Gutachten war in einem Zivilprozess zu erstatten. Nach dem Gerichtsauftrag sollte zu folgenden Parteibehauptungen Stellung genommen werden:
Burg, Heinz
Die Amtliche Sammlung von Untersuchungsverfahren nach ß 64 LFGB, ß 35 Vorl‰ufiges Tabakgesetz und ß 28b Gentechnikgesetz - ein Instrument der amtlichen Lebensmittel¸berwachung
NASA Astrophysics Data System (ADS)
Immer wieder werden Skandale in Zusammenhang mit Lebensmitteln bekannt. Schlagworte wie BSE, Gammelfleisch, Acrylamid, Cumarin oder auch Melamin, Dioxin sind den Verbrauchern gel‰ufig und ersch¸ttern das Vertrauen in ein gesundes und ern‰hrungsphysiologisch wertvolles Lebensmittel. Das Bewusstsein des Verbrauchers hinsichtlich der Ern‰hrung und der Auswahl beim Kauf der Lebensmittel hat sich in den vergangenen Jahren deutlich ver‰ndert. Bei der Auswahl seiner Lebensmittel liegt sein Augenmerk verst‰rkt auf gesunden, qualitativ hochwertigen und vor allem sicheren Lebensmitteln. Dies wurde insbesondere bei dem verhaltenen Kauf von Fleisch und Fleischerzeugnissen w‰hrend der BSE-Krise oder auch dem k¸rzlich aufgetretenen Gammelfleischskandal deutlich.
Renger, Silke; Stachel, Carolin
Dynamic observations of the 8 January 2010 pyroclastic flow from the Soufriere Hills Volcano, Montserrat ascertained by high-definition and FLIR video analysis, as well as geometric analysis of the DEM
NASA Astrophysics Data System (ADS)
On January 8th 2010, Soufriere Hills Volcano (Montserrat) experienced a collapse of the northwestern part of its andesitic lava dome. The ensuing explosive event lead to a 8.3 km high eruption column and generated a pyroclastic density current (PDC) that propagated down the northern flank of the volcano, moving down the Belham valley. This PDC was recorded from the Montserrat Volcano Observatory using both normal High- Definition and Forward Looking Infrared (FLIR) video cameras. The flow front velocity profile, plus the vertical motion of discrete buoyant thermals ascending above the PDC, were measured by combining the video data with a deposit map and a high spatial-resolution DEM. A theoretical treatment was then applied to extract key parameters that describe the buoyant motion of thermals ascending above the current (including density, particle mass volume fraction, and temperature). Interaction of the PDC with topographic features corresponded to important changes in the dynamics of the PDC as well as the ascent of the buoyant ash-clouds These interactions included an increase of the ascent rate of buoyant thermals when the PDC encountered topographic barriers, and deceleration of the flow front velocity due of high degrees of valley sinuosity. Additionally, a major change in flow dynamics was visible in our data 2 - 3 km from the dome. To investigate this further, channel slope, sinuosity, and cross-sectional area were measured from high-resolution DEMs using GIS software; and were compared to geometric parameters of the mapped ash-cloud surge deposits. The data illustrate three surge generation regimes: a proximal area of rapid lateral expansion; a medial deflation zone; and a steadier distal surge 'fringe'. These surge regimes relate directly the dramatic change in buoyant thermal flow dynamics observed 2-3 km from the dome and are also correlated with velocity and inversely correlated with valley cross-sectional area. Several possible origins can be proposed to explain this change, including changes in internal factors (i.e. degree of fluidization, sedimentation rate, and ash generation from block fragmentation) and/or external factors (influence of topographic barriers, changes in slope, sinuosity, valley-holding capacity). Complementary laboratory and dynamical observation would better constrain variations in the dynamics. Areas of topography-induced increases in velocity and inter-granular collisions are interpreted to result in more pervasive fluidization and thus enhanced surge generation. Distally, surge deposits appear as fringes with decaying extents, indicative of more passive expansion and decreasing velocity. The results indicate that surge mobility and detachment are a complex product of flow mass flux and topography and that future efforts to model dense-dilute coupled flows will need to account for and integrate several mechanisms acting on different parts of the flow.
Molle, A.; Ogburn, S. E.; Calder, E. S.; Roche, O.; Harris, A. J.
On relative measurements of the viscosity of gases by the oscillating-disk method
Zusammenfassung Die Abhandlung enth‰lt die Ableitung einer Arbeitsgleichung f¸r Relativmessung der Z‰higkeit, bei der nach der Methode der oszillierenden Scheibe eine d¸nne Scheibe zwischen zwei feststehenden Platten Drehschwingungen ausf¸hrt. In der Formel ist der Randeinfluss nachKestin undWang durch den sogenannten Randkorrekturfaktor ber¸cksichtigt. Dieser aus dem Verh‰ltnis des wirklichen Reibungsmomentes zum theoretischen sich ergebende Faktor ist abh‰ngig von der Geometrie der
Joseph Kestin; Wolfgang Leidenfrost; C. Y. Liu
A porcine coronary stent modelof increased neointima formation in the left anterior descending coronary artery
Zusammenfassung Hintergrund Verschiedene klinische Studien haben f¸r den R. interventrikularis anterior (RIVA) im Vergleich zum R. circumflexus und der rechten Koronararterie (RKA) eine hˆhere Restenoserate nach Koronarintervention gezeigt. In tierexperimentellen Untersuchungen konnte eine enge Beziehung zwischen der Stent-induzierten Gef‰þverletzung und dem Ausmaþ der Neointimabildung nachgewiesen werden. Das Ziel dieser Studie war es, den Einfluss des RIVA und der RKA auf
J. Hausleiter; M. Sebastian; A. N. Li; C. K. Abbey; H. Honda; R. Makkar; J. S. Whiting; N. Eigler
pTheoretischer Hintergrund: Embodiment Theorien postulieren eine enge reziproke Wechselwirkung zwischen dem motorischen System und emotionalen Prozessen. In einer Serie von mehreren Studien wurde untersucht, ob sich (1) Unterschiede in den Gangmustern von akut und niemals depressiven Personen zeigen; (2) ob sich solche Gangcharakteristika auch bei nicht-depressiven Personen nach Induktion von trauriger Stimmung zeigen; (3) ob sich auch bei ehemals depressiven
J. Michalak; N. F. Troje; T. Heidenreich
Tobramycin-Spiegel im menschlichen Lungengewebe
Zusammenfassung Es wird bei 27 Patienten experimentell nachgewiesen, daþ im menschlichen Lungengewebe nach einer intramuskul‰ren Injektion von 80 mg Tobramycin Konzentrationen entstehen, die etwa zwei Stunden lang ¸ber der minimalen Hemmkonzentration der meisten Problemkeime liegen. In 14 Proben aus dem Muskulus latissimus dorsi wurden bis zu zwei Stunden nach Injektion der gleichen Dosis keine nachweisbaren Tobramycin-Konzentrationen gefunden. Der Quotient zwischen
U. Kroening; S. Liebig; M. Wundschock
Classification of honeys by principal component analysis on the basis of chemical and physical parameters
Zusammenfassung 18 chemische und physikalische Parameter der Nektar- und Honigtauhonige wurden bestimmt und die Ergebnisse statistisch mit Hilfe der Hauptkomponentenanalyse ausgewertet. Danach konnten die Honige in folgende Gruppen unterteilt werden: 1) Akazienhonige, 2) Rapshonige, 3) Linden-, Bl¸ten-und Heidehonige, 4) Honigtauhonige. Zwischen dem Nektarhonig und Honigtauhonig lagen wahrscheinlich die Proben von Mischhonigen aus Bl¸ten- und Waldtracht. Die bedeutendste erste Hauptkomponente war
Alina Krauze; Romuald I. Zalewski
Untersuchungen ¸ber den Einfluþ der Myo-Sensorik der Augenmuskeln auf die egozentrische Lokalisation beid‰ugiger optischer Nachbilder
Zum Beweis der Mitbeteiligung der Myo-Sensorik der Augenmuskulatur bei den menschlichen Raumsinnwahrenhmungen wird von Nachbildexperimenten unter den Bedingungen passiver Bulbusexkursionen berichtet. Es lieþ sich zeigen, daþ zwischen der egozentrischen Lokalisation transfovealer Nachbilder und dem Stellungsfaktor der Augen (Myo-Sensorik der Augenmuskulatur) gesetzm‰þige Beziehungen bestehen.
O. Oppel
Bestimmung von Zuckern mit dem Auto Analyzer
An automatic method is described for the determination of sugars in fermentation solutions by means of the Technicon AutoAnalyzer. A solution of cysteine hydrochloride in conc. sulphuric acid is employed as reagent. Up to 30 samples can be analysed within 1 hour. The method has to be tested by a fermentation experiment in the case of a mixture of several
K. Buchta
Dem Bones Forensic Resurrection of a Skeleton
NSDL National Science Digital Library
In this case study, a forensic anthropologist must determine the age and sex as well as look for signs of trauma to a skeleton found in a shallow grave in a state park. Students simulate the actual procedures used in a forensics lab and learn to identify bones, landmarks, and anatomical features associated with sex, age, height, and pathology. The case was developed for use in a freshman-level human anatomy and physiology course. It could also be used in biology, anatomy, and anthropology courses.
Bruce, Alease S.
Diesel Exhaust in Miners Study (DEMS)
In March 2012, the National Cancer Institute (NCI) and the National Institute for Occupational Safety and Health (NIOSH) completed a retrospective cohort mortality and nested case-control study of 12,315 workers at eight non-metal mining facilities to investigate risk of lung cancer in relation to quantitative measures of historical exposure to diesel exhaust, after taking into account smoking and other lung cancer risk factors
NASA Astrophysics Data System (ADS)
In the present paper, I focus on the O'Connell effect of the WUMa variable V502 Cyg, with the main aim of showing it in the lightcurve. 166 observations were collected in V and B band (100 and 66 measurements, respectively) from my private observatory in K‰stenberg, Austria, Ossiacher Tauern, at an elevation of 890 m. All data were acquired with an Apo 130/1200 and an Apogee Alta U16M CCD camera. Photometric colour band and narrowband data were collected simultaneously and evaluated. The combination of photometric data with data for deep-sky imaging I have termed "pretty-picture-photometry". This combination of photometric measurements with colour and narrowband data is presented here in the case of V502 Cyg in its surrounding deep-sky field. Norbert Reichman is member of the BAV.
Reichmann, Norbert
DEM generation by contour line dilation
A method is developed to generate digital elevation models by means of the dilation of contour lines stored in a raster grid. An iterative procedure produces an extension of contour lines by applying alternative four-connected and eight-connected erosions of the background until the produced surfaces become contiguous. The limits between these surfaces correspond to a new family of intermediate contour
Hind Taud; Jean-FranÁois Parrot; Roman Alvarez
Dem Generation with WORLDVIEW-2 Images
NASA Astrophysics Data System (ADS)
For planning purposes 42 km coast line of the Black Sea, starting at the Bosporus going in West direction, with a width of approximately 5 km, was imaged by WorldView-2. Three stereo scenes have been oriented at first by 3D-affine transformation and later by bias corrected RPC solution. The result is nearly the same, but it is limited by identification of the control points in the images. Nevertheless after blunder elimination by data snooping root mean square discrepancies below 1 pixel have been reached. The root mean square discrepancy at control point height reached 0.5 m up to 1.3 m with a base to height relation between 1:1.26 and 1:1.80. Digital Surface models (DSM) with 4 m spacing have been generated by least squares matching with region growing, supported by image pyramids. A higher percentage of the mountainous area is covered by forest, requiring the approximation based on image pyramids. In the forest area the approximation just by region growing leads to larger gaps in the DSM. Caused by the good image quality of WorldView-2 the correlation coefficients reached by least squares matching are high and even in most forest areas a satisfying density of accepted points was reached. Two stereo models have an overlapping area of 1.6 km times 6.7 km allowing an accuracy evaluation. Small, but nevertheless significant differences in scene orientation have been eliminated by least squares shift of both overlapping height models to each other. The root mean square differences of both independent DSM are 1.06m or as a function of terrain inclination 0.74 m + 0.55 m ? tangent (slope). The terrain inclination in the average is 7∞ with 12% exceeding 17∞. The frequency distribution of height discrepancies is not far away from normal distribution, but as usual, larger discrepancies are more often available as corresponding to normal distribution. This also can be seen by the normalized medium absolute deviation (NMAS) related to 68% probability level of 0.83m being significant smaller as the root mean square differences. Nevertheless the results indicate a standard deviation of the single height models of 0.75 m or 0.52 m + 0.39* tangent (slope), corresponding to approximately 0.6 pixels for the x-parallax in flat terrain, being very satisfying for the available land cover. An interpolation over 10 m enlarged the root mean square differences of both height models nearly by 50%.
B¸y¸ksalih, G.; Baz, I.; Alkan, M.; Jacobsen, K.
Dem Bones: Forensic Resurrection of a Skeleton.
ERIC Educational Resources Information Center
Presents an activity for students to determine the sex and age of an individual from a collection of bones. Simulates some of the actual procedures conducted in a forensic anthropologist's lab, examining and identifying bones through a series of lab activities. (Author/ASK)
Bruce, Alease
Die ersten Ergebnisse mit dem intratubaren Embryotransfer
\\u000a SummaryÝÝThe intratubal transfer of pronucleus or early cleavage stage embryos (2ñ8-cell stage) is a new method in the treatment of\\u000a human infertility. Following transvaginal sonographic oocyte retrieval in vitro fertilization is performed and the fertilized\\u000a (pronucleus-stage) or embryos are transferred into the tube by laparoscopy. In comparison to GIFT (intratubal gamete transfer)\\u000a fertilization under in vitro conditions offers the advantage
K. Diedrich
Groþstadt und Geschlechterordnung: Geschichten aus dem Kino
In der Geschlechterforschung werden zunehmend Vorstellungen einer stabilen - meist essentialistisch gedachten - Geschlechterdichotomie und deren Verl‰ngerung in entsprechend duale r‰umlich- topographische Aufteilungen in Frage gestellt. Besonders am Ph‰nomen groþer St‰dte, so wird behauptet, verdichte sich die Problematisierung der Geschlechterverh‰ltnisse. F¸r manche Stadtfilme der neunziger Jahre trifft dies zu: Es l‰þt sich ganz gut beobachten, daþ Geschlechterrollen ihre Eindeutigkeit und
Dorothea Kress
Future earthquake source faults on deep sea-floor around the Boso triple plate junction revealed by tectonic geomorphology using 3D images produced from 150 meter grid DEM
NASA Astrophysics Data System (ADS)
Boso triple junction, which is the only example of a triple trench junction on earth, is located off the southeast of Boso peninsula, where the Izu-Bonin trench meets with the Japan trench and the Sagami trench. Boso submarine canyon, which is extended to Katsuuma basin about 7000m deep, forms an incised meander along the north side of Sagami trough. Taito spur separate Katsuuma basin from Bando abyssal basin about 9000m deep, where Japan trench meet with Isu-Bonin trench. In this paper, we present detailed stereo-paired topographic images produced from 0.002 degree (about 150m) DBEM (Digital Bathymetry Model), which processed from the depth sounding data obtained by Japan Coast Guard and JAMSTEC around Boso triple junction. It enables us to observe submarine geomorphology easily and precisely. We identified submarine active faults and other tectonic features related to subduction by using the similar standard for air-photo interpretation of inland active faults. We made more precise submarine active tectonic geomorphological map around Boso triple junction than that by previous workers. Numerous distinct faults on the so-called outer rise associated with subduction of Pacific plate are regarded as normal faulting as widely accepted. While the normal faults on the outer rise are parallel to the trench in the southern part of the Japan trench and the northern part of the Izu-Bonin trench, these normal faults around the east of the triple junction with NNW-SSE extend slightly oblique to the trench. The western margin of Bando abyssal basin is bounded by the thrust faults, which form east-facing 200-500m-high convex scarps associated with raised basin floor to the west of the scarp. These faults also deform Mogi submarine fan surface and uplift to the west along the extension of the scarp. The antecedent valley is extended for about 10km across Taito spur that is an active anticlinal ridge about 1000m high. Katsuura basin is surrounded by terraced former basin floor that is tilted to the west, indicating up-growing of Taito spur. Northeastern part of Izu bar on Philippine Sea plate is characterized by rather smooth extensive convex slope between 1500m-7500m for over 200km long along the trench. On the lower part of the slope below 6000m, several gullies such as Mikura canyon and Kita-Hachijo canyon dissecting the slope forms rapids, probably due to continuous up-warping by subsurface thrusting dipping to the west under the slope. It is noteworthy that we can identify prominent active tectonic features on even very deep sea-floor along the plate boundaries, by using 3D images produced from 150 meter grid DEM.
Goto, H.; Nakata, T.; Watanabe, M.; Suzuki, Y.; Izumi, N.; Nishizawa, A.; Horiuchi, D.; Kido, Y. N.
NASA Astrophysics Data System (ADS)
Das Flieþpressen z‰hlt neben dem Stauchen und Gleitziehen zu den Kernverfahren des Kaltmassivumformens. In beschr‰nktem Maþe wird es auch im halbwarmen Bereich zwischen 600∫C und 800∞C werkstoff- oder verfahrensbedingt angewandt. Besondere technisch-wirtschaftliche Bedeutung hat das Kaltflieþpressen von Stahl erlangt, nachdem 1934 durch Phosphatieren der Rohteile nach dem Singer-Patent die sichere Umformung von Stahlwerkstoffen in Stahlwerkzeugen ohne Kaltverschweiþen mˆglich geworden war. Die Werkst¸ckmassen liegen beim Kaltflieþpressen zwischen wenigen Gramm und einigen Kilogramm, seltener auch dar¸ber. Grenzen sind die Werkzeugbelastung einerseits und die hohen Umformkr‰fte andererseits. Grunds‰tzlich lassen sich fast alle knetbaren Metalle durch Flieþpressen umformen. Heute ist diese Verfahrensgruppe eine leistungsf‰hige Technologie, die die Fertigung pr‰ziser, geometrisch komplexer, hochbeanspruchbarer Werkst¸cke aus hochfesten St‰hlen f¸r weite Einsatzbereiche mit geringstem Werkstoffeinsatz ermˆglicht.
Lange, Kurt
Energieverlust von ?-R¸ckstoþkernen in Formvar
Zusammenfassung Es wurden die Energieverteilungskurven der R¸ckstoþkerne des ThC'-a-Zerfalls (Anfangsenergie 169 keV) nach dem Durchgang durch Formvarfolien zwischen 1,4 und 7,0 µg\\/cm2 Dicke mit Hilfe einer elektronischen Laufzeitmessung ermittelt. Die Spektren zeigen bei d¸nnen Folien stark asymmetrische Formen, die sich qualitativ durch die sehr kleinen mittleren Stoþzahlen erkl‰ren lassen. Eine Gauþ-Verteilung wird bis zu Foliendicken der halben Reichweite nicht erreicht.
P. Zahn
Kreuzreaktive Allergenkluster bei pollenassoziierter Nahrungsmittelallergie
Zusammenfassung Soforttyp-Symptome durch Allergene ohne vorangegangene prim‰re Sensibilisierung beruhen h‰ufig auf kreuzreaktiven IgE-Antikˆrpern. Sie sind die Basis f¸r pollenassoziierte Nahrungsmittelallergien mit Kern- und Steinobstunvertr‰glichkeit bei Birkenpollen- oder Sellerie- und Gew¸rzallergie durch eine Beifuþpollensensibilisierung. Gut untersucht ist die ƒhnlichkeit zwischen dem Birkenpollen-Majorallergen Bet v 1 und zahlreichen Stressproteinen aus der gleichen Familie (PR-10-Proteine), die in Haselnuss, Obst- und Gem¸sesorten vorkommen. Andere
J. Kleine-Tebbe; D. A. Herold
Populistisch und unkonkret Die unmittelbare Wahrnehmung des TV-Duells
Welche Aussagen in einem TV-Duell am besten ankommen, ist eine der zentralen, aber empirisch eher selten untersuchten Fragen\\u000a der Debattenforschung. Dies ist umso verwunderlicher, als Spekulationen ¸ber die Ñentscheidenden Stellenì einer Fernsehdebatte\\u000a zum Standardrepertoire der Nachberichterstattung geh¸ren. Nicht selten werden sogar Sieg und Niederlage in einem TV-Duell\\u000a an einzelnen Statements der Kandidaten festgemacht (Maurer\\/Reinemann 2007). Auch nach dem TV-Duell zwischen
Carsten Reinemann; Marcus Maurer
Fokus eGovernment: Verwaltungsreformen und Beratereinsatz
\\u000a Unter dem Begriff eGovernment verfolgen seit Ende der neunziger Jahre eine Reihe von Verwaltungseinheiten insbesondere solche\\u000a Reformans‰tze, die verst‰rkt Informations- und Kommunikationstechnologien einsetzen. An zentraler Stelle steht die Nutzung\\u000a des Internets. Damit sollte vor allem der Gesch‰ftsverkehr mit B¸rgern und Unternehmen sowie zwischen Verwaltungen elektronisch\\u000a abgewickelt werden. Dar¸ber hinaus erhoffte man sich, vor allem zu Beginn der eGovernment-Ideen, neue Formen
Thomas Armbr¸ster; Johannes Banzhaf; Lars Dingemann
The association between body-mass index and patient outcome in septic shock: a retrospective cohort study
\\u000a ZusammenfassungÝÝHINTERGRUND: Es bestehen keine Daten ¸ber die Assoziation zwischen dem Body Mass Index (BMI) bzw. BMI Kategorien und der Mortalit‰t\\u000a von septischen Schock-patienten. METHODEN: Die Datenbank einer interdisziplin‰ren Intensivstation wurde retrospektiv nach\\u000a erwachsenen Patienten mit septischem Schock durchsucht. Von allen Patienten wurde der BMI, demographische, klinische und laborchemische\\u000a Parameter gemeinsam mit Outcomevariabeln dokumentiert. Die Studienpatienten wurden wie folgt anhand des
Bettina Wurzinger; Martin W. D¸nser; Christoph Wohlmuth; Martina C. Deutinger; Hanno Ulmer; Christian Torgersen; Christian A. Schmittinger; Wilhelm Grander; Walter R. Hasibeder
In den aktuellen Klassifikationssystemen der WHO und der Amerikanischen Psychiatrischen Gesellschaft (APA) wird zwischen wahnhaften\\u000a und nichtwahnhaften Formen der kˆrperdysmorphen Stˆrung unterschieden. In der ICD-10 (Dilling et al. 1991) ist eine Zuordnung entweder zu den wahnhaften Stˆrungen (F22.0) oder zur Hypochondrie (F45.2) vorgesehen. Beiden Krankheitsformen\\u000a gemeinsam ist eine intensive Besch‰ftigung mit dem eigenen Aussehen aus der Ðberzeugung heraus, missgestaltet zu
Dirk Schmoll
Wie geht es weiter nach DSL? Entwicklungsperspektiven der Versorgung mit Breitband-Internet
\\u000a In nur wenigen Bereichen der Nachfrage nach Dienstleistungen wurde bislang das Verhalten der Nutzer in so durchschlagender\\u000a Weise von Technologieangeboten und deren Qualit‰tsmerkmalen gepr‰gt wie im Telekommunikationssektor und hier speziell beim\\u000a Internetzugang. In den 90er Jahren dominierte zun‰chst das Analog-Modem mit Geschwindigkeiten zwischen 9,6 und 56 kbit\\/s und\\u000a heftete dem Internet das Image an, prim‰r ein Medium einer kleinen, technikaffinen
Franz B¸llingen
Das Bild vom demokratischen Soldaten: Erste Ergebnisse der empirischen Fallstudie zur Bundeswehr
\\u000a In welchem Verh‰ltnis stehen demokratische Gesellschaften zum Milit‰r, und wie dr¸ckt sich dies im jeweiligen Soldatenbild\\u000a aus? Diesen Fragen widmet sich das Forschungsprojekt mit dem Titel ÑDas Bild vom demokratischen Soldaten: Spannungen zwischen\\u000a der Streitkr‰fteorganisation und den Grunds‰tzen der Demokratie im europ‰ischen Vergleichì, das seit Mai 2006 mit einer Laufzeit\\u000a von drei Jahren an der Hessischen Stiftung Friedens- und Konfliktforschung
Julika Bake
Politische F¸hrung im Zeichen der Vergangenheitsbew‰ltigung: Argentinien
N‰hert man sich dem Ph‰nomen der politischen F¸hrung in Lateinamerika bzw. in Argentinien, gilt der erste Blick den Regierungssystemen\\u000a der betreffenden Staaten. Der Pr‰sidentialismus ist die vorherrschende Regierungsform in lateinamerikanischen Staaten. Als\\u000a Vorbild diente ihnen die Funktionslogik des US-amerikanischen Regierungssystems. Doch l‰sst sich in Lateinamerika im Allgemeinen\\u000a und in Argentinien im Besonderen eine deutliche Diskrepanz zwischen Verfassungstext und Verfassungswirklichkeit beobachten.
Tobias Nerb
NASA Astrophysics Data System (ADS)
Wirtschaftliches Wachstum ist mit steigenden Anforderungen an Mobilit‰t und Transport verkn¸pft. Zukunftsorientierter Fortschritt muss hierbei die Wirkungen von Verkehrsger‰uschen auf Mensch und Umwelt ber¸cksichtigen, um eine hohe Lebensqualit‰t sicherstellen zu kˆnnen. Mehr als die H‰lfte der Bevˆlkerung in der EU f¸hlt sich durch Verkehrsl‰rm bel‰stigt oder bef¸rchtet direkte Auswirkungen auf Gesundheit und Wohlbefinden. Nach einer repr‰sentativen Umfrage des Umweltbundesamtes f¸hlen sich durch Straþenverkehrsl‰rm 20 % der Bevˆlkerung stark oder wesentlich bel‰stigt (UBA 2008). Daher ist das "Fahrzeug-Auþenger‰uschì Gegenstand zahlreicher Forschungsprojekte zu Themen wie Identifikation wesentlicher Ger‰uschquellen, Zusammenhang zwischen Verkehrsger‰usch und Bel‰stigung, medizinische Folgen aufgrund chronischer L‰rmexposition, Ger‰uschqualit‰t, Entwicklung neuer Methoden und Technologien zur Fahrzeug-Auþenger‰uschmessung und das Fahrzeug-Auþenger‰usch als wesentliches Produktattribut, das aktiver Gestaltung bedarf.
Genuit, Klaus
Zusammenh‰nge zwischen der Reduktion von Disulfidbindungen und der Molekulargewichtsverteilung bei Weizenkleber
Summary The complete reduction of succinylated wheat (variety Kolibri) gluten (Ksucc) with dithiothreitol leads to 210 µmol SH-groups\\/g protein. Gelchromatography on Sepharose 6B-Cl shows, that a complete reduction of Ksucc involves a strong decrease of the protein fraction with very high molecular weight. A partial and stepwise reduction of Ksucc with increasing concentrations of mercaptoethanol leads to an 80% decrease
Renate Seeger; Hans-Dieter Belitz
Untersuchung der ferromagnetischen Produkte der explosiven reaktionen zwischen Ammoniumeisencyanid und Kupfernitrat
The wet mixtures of ammonium hexacyanoferrate, (NH4)4[Fe(CN)6], and cupric nitrate, Cu(NO3)2, react explosively when heated at 220 áC. Among the solid products studied by chemical analysis, magnetic measurements and X-ray diffraction there are magnetite (Fe3O4), iron nitride (Fe4N), gamma iron oxide (?-Fe2O3), cuprous oxide (Cu2O), alpha iron oxide (?-Fe2O3), cupric oxide (CuO), cuprous ferrite and metallic copper. Furthermore cupric hexacyanoferrate
W. Wolski; J. Skrzypczak
Zwischen Reform und Blockade ñ die Bilanz der Groþen Koalition 2005-2009
\\u000a Die Groþe Koalition aus CDU\\/CSU und SPD, die 2005 Angela Merkel zur Bundeskanzlerin w‰hlte, war kein politisches Projekt.\\u000a Beide Partner hatten vor der Bundestagswahl 2005 andere Koalitionen favorisiert und hatten sich entsprechend einen ausgesprochen\\u000a konfrontativen Wahlkampf geliefert. Als jedoch die Arithmetik die pr‰ferierten Zweierb¸ndnisse nicht zulieþ, denkbare Koalitionen\\u000a aus drei Parteien nicht realisiert werden konnten und eine wie auch immer
Reimut Zohlnhˆfer; Christoph Egle
Modellierung der Rand¸berstrˆme zwischen Erftscholle, Rurscholle und Venloer Scholle durch Kopplung von Groþraum-Grundwassermodellen
NASA Astrophysics Data System (ADS)
Three large-scale groundwater models were developed for the purpose of water resources management during open pit mining activities. The area of interest is a part of the Lower Rhine Embayment, the modelling areas cover the geological units (blocks) of the Venlo terrain, the Rur terrain and the Erft terrain, which are separated by geologic faults. The groundwater interchange between the three blocks is modelled by setting shared boundary conditions at which the interchange was equilibrated in an iterative process. By coupling the three models numerically using finite beam elements, the process of adjusting the boundary conditions can be avoided. The beam elements only model the interchange paths between the blocks, but not the block-separating faults themselves. Therefore, this method is appropriate for large-scale modelling, because arbitrary interchange paths can be modelled without describing the faults in detail.
Becker, B.; Kˆngeter, J.; Klauder, W. S.; Reuter, C.
Ðber den Wirkungsmechanismus des Ephedrins und den Unterschied in der Wirkungsst‰rke zwischen seinen Isomeren
Zusammenfassung 1.Die Blutdruckwirkung des Ephedrins ist nicht als Herzwirkung aufzufassen. Sie ist eine rein periphere Gef‰þwirkung und kommt dadurch zustande, daþ durch das Ephedrin die Gef‰þe f¸r Suprarenin sensibilisiert werden. An und f¸r sich unwirksame Ephedrinkonzentrationen verursachen an den mit verd¸nnten Suprareninlˆsungen durchstrˆmten Froschgef‰þen eine starke, langanhaltende Vasokonstriktion.2.Mit derselben Methode l‰\\\\t sich auch die sensibilisierende Wirkung des Kokains und die
Otto Schaumann
Beziehungen zwischen Kˆrperbau und Lebensweise bei Blenniidae (Pisces) des Roten Meeres
The muscle and skeleton anatomy of the pectoral, pelvic, and anal fins are described in 3 Salariin Blenniidae: Salarias fasciatus (sublittoral), Istiblennius edentulus (eulittoral), Alticus kirkii (supralittoral). In A. kirkii these organs are adapted to a climbing habit on the steep rocks beyond the water. The results are compared with those found in Periophthalmus.
C. Dieter Zander
Beziehungen zwischen Aktivit‰t corticaler Neurone und EEG-Wellen im motorischen Cortex der Katze bei Hypoglyk‰mie
1.The EEG, recorded monopolarly from the pial surface, was investigated during insuline induced hypoglycemia in acute cats and compared with the activity of cortical cells recorded with intra or ìquasi-intracellularî electrodes.2.Pathological changes of the EEG were observed only when the blood glucose fell below 25ñ30 mg-%. Electrical silence was observed at blood glucose levels below 15ñ10 mg-%.3.The essentially flat, ìdesynchronizedî
D. Mergenhagen; O. Creutzfeldt; G. Neuweiler
Kompetitiver Antagonismus zwischen g-Strophanthin und Corticosteron an isolierten Streifen von Rattenaorten
\\u000a SummaryÝÝCorticosterone was shown to have an inhibitory effect on the contraction caused by a cardiac glycoside (g-Strophanthin = Ouabain)\\u000a in isolated strips of rat aorta. It could be demonstrated that over a tenfold concentration range of Ouabain, the kinetics\\u000a of this antagonism are in accord with the assumption of a competitive inhibition.
H. J. Schatzmann
Kardiorespiratorische Parameter verglichen zwischen nordic walking und walking in Hˆhen- und Tallage
Ziel der Untersuchung war es zum einen, Nordic Walking mit Walking bez¸glich Ventilation, Sauerstoffaufnahme, Herzfrequenz, Energieverbrauch, Borg und Sauerstoffs‰ttigung (V'e, Vo2, Hf, EE, Borg, SaO2) unter Feldtest Konditionen zu vergleichen und zum anderen, jene Parameter in Hˆhen- (1600m) und Tallage (600m) zu vergleichen.
Hannes Zischg; Georg Spazier
Zwischen existentieller Sinnerf¸llung und Burnout: eine empirische Studie aus existenzanalytischer Perspektive
\\u000a AbstractÝÝThe phenomenon of burnout is interpreted on the background of psychoanalytic and socialpsychological perspectives from an\\u000a existential analytic point of view. The basic condition of its origin is seen as a nonexistential attitude towards life, stemming\\u000a from a deficit in personal-existential fundamental supports. A person in this position longs for a fulfilled life but has\\u000a no orientation in the most
Anton Nindl; Alfried L‰ngle; Erich Gamsj‰ger; Joachim Sauer
Fahrerassistenz und Verkehrssicherheit
NASA Astrophysics Data System (ADS)
Einer weit verbreiteten Auffassung zufolge sind ca. 95 % aller Unf‰lle im Straþenverkehr zumindest anteilig auf die Ursache "Human Errorì zur¸ckzuf¸hren. Weiterhin soll menschlichem Fehlverhalten bei ca. 75 % der Straþenverkehrsunf‰lle der Status einer "Alleinursacheì zukommen [1] [7]. Zitiert wird in diesem Zusammenhang h‰ufig eine fr¸he Studie von Treat und Mitarbeitern [5], die aufgrund einer Detailanalyse von 2.258 Unfallprotokollen zu dem Ergebnis kam, dass menschliches Fehlverhalten als Ursachenfaktor in 93 % der F‰lle (gegen¸ber 34 % Umweltfaktoren und 13 % Fahrzeugfaktoren) beteiligt waren. Ungeachtet der erkenntnistheoretischen Probleme, die ein allzu leichtfertiger Umgang mit dem Ursachenbegriff in diesem Falle mit sich bringt, d¸rfen die Entstehungsbedingungen "menschlichen Versagensì [6] nat¸rlich nicht unreflektiert bleiben, wenn es um die Entwicklung zielf¸hrender Ans‰tze und Maþnahmen zur Einschr‰nkung des Unfallgeschehens geht. Eine im Zusammenhang mit "menschlichem Versagenì h‰ufig thematisierte Unfallursachenkategorie ist beispielsweise die des "Looked-but-Failed-to-Seeì. Gemeint sind damit Unf‰lle, bei denen sich das kritische Hindernis oder Fahrzeug durchaus im Sehfeld der den Unfall verursachenden Fahrer befand, ohne dass es von ihnen erkannt wurde, um auf dieser Grundlage dann die erforderlichen, den Unfall mˆglicherweise vermeidenden Fahrhandlungen auszuf¸hren. Aus psychologischer Sicht wird dieses Ph‰nomen zumeist mit Kapazit‰tsbegrenzungen der visuellen Aufmerksamkeit, der Selektivit‰t des Prozesses des visuellen Abtastens oder der fehlerhaften Integration relevanter Merkmale der Szenerie erkl‰rt [1].
Gelau, Christhard; Gasser, Tom Michael; Seeck, Andre
DEM L71: Shock Physics at High Resolution
In a small sub-sample of SNRs, the X-ray and radio emission from the blast wave is accompanied by optical (Balmer) line emission. The line profiles of these Balmer-dominated spectra provide a direct measurement of the proton temperature at the shock front, thus also placing stringent limits on the shock velocity. Combining this with the Chandra X-ray measured electron temperature provides
C. E. Rakowski; P. Ghavamian; J. P. Hughes; T. B. Williams
Lufthansa VOR Dem Binnenmarkt (Lufthansa Facing the Single European Market).
National Technical Information Service (NTIS)
Lufthansa's situation in the context of a single European market and the changes in the global air transportation industry is described. Lufthansa must compete with European airlines, American carriers, and Asiatic air companies whose cost structures are ...
A. C. Pfeil
Erste klinische Erfahrungen mit dem Argonlaser bei der Rhinopathia vasomotorica
The construction of a laser-beam-guide system for application in the nasal cavity is presented. An Ar+-laser beam of 1ñ3 W is conducted to the end tube of 4 mm diameter using two movable arms connected with two rotating mirrors. The beam diameter at the exit of the system is 0.7 mm. The technical procedure for the application of the laser
H. Lenz; J. Eichler; G. Sch‰fer; J. Salk; J. Knof
NSDL National Science Digital Library
Today, you are going to practice finding multiples and solving fraction problems! FIRST, you are going to help the Mayor of Pumpkinville find multiples! Begin with the number 2. You will need to collect FIVE multiples of 2 BEFORE choosing another number. Find multiples of numbers 3 through 12 before moving to the next game. GOOD LUCK! CLICK HERE --> Pumpkin Multiples Once you ...
Smith, Ms.
DEM Solutions Develops Answers to Modeling Lunar Dust and Regolith
NASA Technical Reports Server (NTRS)
With the proposed return to the Moon, scientists like NASA-KSC's Dr. Calle are concerned for a number of reasons. We will be staying longer on the planet's surface, future missions may include dust-raising activities, such as excavation and handling of lunar soil and rock, and we will be sending robotic instruments to do much of the work for us. Understanding more about the chemical and physical properties of lunar dust, how dust particles interact with each other and with equipment surfaces and the role of static electricity build-up on dust particles in the low-humidity lunar environment is imperative to the development of technologies for removing and preventing dust accumulation, and successfully handling lunar regolith. Dr. Calle is currently working on the problems of the electrostatic phenomena of granular and bulk materials as they apply to planetary surfaces, particularly to those of Mars and the Moon, and is heavily involved in developing instrumentation for future planetary missions. With this end in view, the NASA Kennedy Space Center's Innovative Partnerships Program Office partnered with OEM Solutions, Inc. OEM Solutions is a global leader in particle dynamics simulation software, providing custom solutions for use in tackling tough design and process problems related to bulk solids handling. Customers in industries such as pharmaceutical, chemical, mineral, and materials processing as well as oil and gas production, agricultural and construction, and geo-technical engineering use OEM Solutions' EDEM(TradeMark) software to improve the design and operation of their equipment while reducing development costs, time-to-market and operational risk. EDEM is the world's first general-purpose computer-aided engineering (CAE) tool to use state-of-the-art discrete element modeling technology for the simulation and analysis of particle handling and manufacturing operations. With EDEM you'can quickly and easily create a parameterized model of your granular solids system. Computer-aided design (CAD) models of real particles can be imported to obtain an accurate representation of their shape. EDEM(TradeMark) uses particle-scale behavior models to simulate bulk solids behavior. In addition to particle size and shape, the models can account for physical properties of particles along with interaction between particles and with equipment surfaces and surrounding media, as needed to define the physics of a particular process.
Dunn, Carol Anne; Calle, Carlos; LaRoche, Richard D.
Zur Technik des Farbfernsehens nach dem PAL-Verfahren
Das Wunder der Farbfernsehtibertragung bedurfte phantasievoller Kombinationen der naturwissenschaftlichen Grundlagen und eigener Erfindungen auf allen drei Teilgebieten, aus denen sich der Farbfernsehvorgang zusammensetzt : Der Bildaufnahme ftir die Signalherstellung, also der optisch-elektrischen Wandlung, der Signaltibertragung und am Ende der Bildwiedergabe, also tier elektrisch-optischen Wandlung. Heute erscheint uns der Ablauf dieser Entwicklung fast selbstverst~tndlich, wie vorgeplant, und bald wird vergessen sein,
Walter Bruch
Politikerinnen in den Medien: Erfahrungen aus dem Journalismus
Es ist keine Frage mehr, ob Frauen das kˆnnen. Sie haben es ja l‰ngst bewiesen, schon vor Jahrzehnten: Indira Gandhi, Golda\\u000a Meir und Margaret Thatcher heiþen die prominenten Beispiele, wichtige Persˆnlichkeiten der Zeitgeschichte. Und nun gehˆrt\\u000a Angela Merkel zum kleinen, elit‰ren Kreis der Regierungschefinnen. Zurzeit ist sie weltweit eine von sechs.
Birgitta Stauber-Klein
A DEM model for contact electrification of irregular shaped particles
NASA Astrophysics Data System (ADS)
Contact electrification may occur during particle-particle and particle-wall collisions due to the contact potential difference. The aim of the current work is to examine the effect of particle shape on contact electrification. A discrete element method was developed to model irregular shaped particles with a multi-sphere representation and to analyse contact electrification using a condenser model. The irregular particles were modelled with a row of clustered primary spheres of various sizes and were characterized using a radial shape index that is defined as the ratio of the size between the distal and central spheres. They were subjected to tribo-electrification in a vertically vibrating container. It was revealed that the charging processes and charge distributions with different radial shape indexes exhibited distinct patterns. Specifically, particles with a large radial shape index acquired higher charge on the distal primary spheres whilst those with a smaller radial shape index gained more charge in the centre. This is due to the difference in contact probabilities associated with non-spherical particles, which leads to non-uniform charge distributions.
Pei, Chunlei; Wu, Chuan-Yu; Adams, Michael; England, David; Byard, Stephen; Berchtold, Harald
Multiscale curvatures for identifying channel locations from DEMs
NASA Astrophysics Data System (ADS)
Curvature based methods are suitable for channel identification in digital elevation models. One obstacle in using these methods is the fact that channels generally occur at multiple scales in the landscape, from small creeks to large rivers. In this paper, we show how likely channel pixels can be identified simultaneously at a range of scales using multiscale curvature operators applied to digital elevation models. Our proposed Hyperscale Channel Extraction (HCE) method localizes channels at the smallest scale while simultaneously tracking the shape of the channel at a full interval of scales (the hyperscale). We test the method using two different types of curvature, and apply and validate it to a catchment representing terrain with a high slope sampled by airborne laser altimetry. The test results demonstrate that by explicitly employing the extra dimension of scale to localize channels, (a) we are able to robustly identify channel pixels, as possible channel locations are tracked through a full interval of scales, (b) no more a priori determination of the relevant scale is necessary, and (c) only one parameter remains to be set: a threshold on the curvature value that has a clear physical interpretation.
Koenders, R.; Lindenbergh, R. C.; Storms, J. E. A.; Menenti, M.
DEM Simulation of Rock Shed Failure due to Rockfall Impact
NASA Astrophysics Data System (ADS)
The rock shed is a more costly but effective traffic facility used to keep out falling rocks in Taiwan. The main function of rock shed is to let the falling rock passing through via the top slab without hitting the road users. The failure mode of the rock shed due to rockfall impact generally includes punching of top slab, flexural cracks of beam, buckling of column, and damage of foundation, etc. Even so, the failure behavior of the rock shed is still complicated and difficult to predict. Accordingly, this study adopts the discrete element program (PFC2D) to simulate the failure behavior of rock shed. A comparison with uniaxial compression test was carried out firstly to determine the micro parameters of structure elements. The model was utilized to simulate the behavior of rock shed with impact load or hitting of falling block separately. Then, a case study of present rock shed of highway NO.18 in middle Taiwan was analyzed. The result indicates that: the primary causes of rock shed failure mode include block size, falling height, impact position, and structure system. The failure mode of punching shear failure or flexural cracks is dominated by block size and falling height. The occurrence of differential settlement is related to impact position and absence of combined footing. Considering the connection of beam and column, the structure is more likely to break at the joints rather than punching of the top slab. As a result, combined footing and beam-to-column joint should be to take into account to obtain safer protection of rock shed. Keywords: rockfall disaster, PFC, rock shed, discrete element method
Chen, Jian-An; Lin, Ming-Lang; Wang, Ching-Ping; Lo, Chia-Ming
Auszug aus dem GVH-Fahrplan - Nur Niederflurbusse mit Rampe
4.48 5.03 5.18 5.33 5.48 6.03 6.22 6.43 7.03 7.13 7.23 7.33 7.39 7.43 7.53 8.03 8.13 8.23 12.23 12.43 13.03 Haberhof 4.49 5.04 5.19 5.34 5.49 6.04 6.23 6.44 7.04 7.14 7.24 7.34 7.40 7.44 7.54 8.04 8.14 8.24 12.24 12.44 13.04 Osterfelddamm 4.50 5.05 5.20 5.35 5.50 6.05 6.24 6.45 7.05 7.15 7.25 7.35 7.41 7.45 7.55 8.05
Alte Heide; Cranzer Weg; Zum Brookland
ASTER DEMs for geomatic and geoscientific applications: a review
Most geoscientific applications using georeferenced cartographic\\/geospatial data require good knowledge and visualization of the topography of the Earth's surface. For example, mapping of geomorphological features is hardly feasible from a single image; three?dimensional (3D) information has to be generated or added for a better interpretation of the two?dimensional data. Since the early emergence of earth observation satellites, researchers have investigated
Thierry Toutin
Famili‰re rekurrierende intrahepatische Cholestase seit dem fr¸hen Kindesalter
Two children (brother and sister) with recurrent intrahepatic cholestasis with jaundice and pruritus since infancy are reported. The first symptoms in the elder sister (case 1) were loose stools and a subnormal course of development. Jaundice was first noticed at the age of 10 months. In the younger brother (case 2) the disease started during the second week of life
Hans Werner Rotthauwe; Ingrid Rotthauwe
Tetrapodenf‰hrten aus dem Perm - Kenntnisstand und Progress 2000
Tetrapod footprints from Permian terrestrial deposits are repesented in the literature by 150 generic and 281 species names. This number was increased by later combination to more than 370 binomina. This large number of ichnotaxa is nonrealistic in relation to the diversity of terrestrial tetrapods. Therefore, earlier faunistic and stratigraphic evaluations from tracks must be problematic. This paper discusses the
"Dem Wod Mo Saf": Materials for Reading Creole English.
ERIC Educational Resources Information Center
As part of a study that sought ways to improve the language arts educational experience for Grenadian children, an anthropologist investigated how Carriacou Creole English (CCE) reading materials could be provided and how these children would react to them. CCE is the native language of the inhabitants of Carriacou, a sister island of Grenada. TheÖ
Kephart, Ronald
NASA Astrophysics Data System (ADS)
Als Gewebe wird ein durch spezifische Leistungen gekennzeichneter Verband gleichartig differenzierter Zellen bezeichnet. Gewebe entstehen aus jungen, noch nicht differenzierten Zellen, die sich ihrer k¸nftigen Funktion entsprechend umwandeln. Gewebe aus differenzierten Zellen wird als Dauergewebe bezeichnet. Verschiedene Gewebe haben allerdings eine mehr oder weniger starke Potenz, sich neu aufzubauen. Beim Menschen unterscheidet man diesbez¸glich zwischen labilem Gewebe, bei dem die Bildung und der Aufbau der Zellen rasch erfolgt, stabilem Gewebe, bei dem der Zellumsatz sehr langsam geschieht und permanentem Gewebe, bei dem absterbende Zellen nicht mehr ersetzt werden kˆnnen (Tabelle 8.1). Es gibt vier Grundtypen von Geweben: Epithelgewebe, Binde- und St¸tzgewebe, Muskelgewebe und Nervengewebe. Im Kˆrper treten in der Regel verschiedene Gewebe funktionell zusammen (z. B. Muskeln und Sehnen des Bindegewebes).
Shah-Derler, Brigitte; Wintermantel, Erich; Ha, Suk-Woo
Definition und Beschreibung klimatologischer Extreme und ihr Zusammenhang mit der Zirkulation. T. 1. Definition und Beschreibung klimatologischer Extreme. (Definition and description of climatological extremes and their interdependence with circulation patterns. Pt. 1. Definition and description of climatological extremes).
National Technical Information Service (NTIS)
It is well known that knowledge on average weather conditions is not sufficient for obtaining climatological information of practical relevance. As a rule, it is the extreme weather conditions that have the most dramatic consequences for agriculture, natu...
P. C. Werner U. Boehm U. Werner
Vergleichende Untersuchungen mit Hilfe von Munsell-Farbtafeln und des CIELAB-Farbsystems zur Winterchlorose von Pinus sylvestris L. im Immissionsgebiet D¸bener Heide
ZusammenfassungÝÝMit dem Farbmeþsystem Pretema 4005 erfolgt an 8 cm2 groþen, mit 2ñ4 mm langen Nadelst¸cken bedeckten Fl‰chen die Messung der Reflexionsspektren von Kiefernnadeln im sichtbaren\\u000a Wellenl‰ngenbereich. Die anschlieþende Berechnung der Farborte im CIELAB-Farbraum ermˆglicht die Erfassung von Farbunterschieden\\u000a zwischen zwei Proben als r‰umlichen Abstand dieser Farborte. Die Gesamtfarbdifferenz wird in einen Helligkeits(lightness)-,\\u000a Brillanz(chroma)- und Farbton(hue)-Beitrag zerlegt, womit die Vergleichbarkeit zur
G. Baronius; H. J. Fiedler; H. G. Montag
Messung der Infiltrationsgeschwindigkeit von Oberfl‰chenwasser mit Hilfe des nat¸rlichen Isotops Radon222
KurzfassungÝÝ\\u000a \\u000a Das nat¸rlich vorkommende Isotop Radon-222 kann wegen deutlicher Konzentrationsunterschiede in Grund- und Oberfl‰chenw‰ssern\\u000a als nat¸rlicher Tracer zur Bestimmung der Aufenthaltszeiten von infiltriertem Oberfl‰chenwasser und der Infiltrationsgeschwindigkeit\\u000a eingesetzt werden. F¸r das Untersuchungsgebiet in der Torgauer Elbaue wurde eine Korrelation zwischen der Radonaktivit‰tskonzentration\\u000a des Grundwassers und dem lithologischen Aufbau des Grundwasserleiters gefunden. Niedrige Radonaktivit‰tskonzentrationen im\\u000a Grundwasser in der N‰he eines Oberfl‰chengew‰ssers
Jˆrg Dehnert; Wolfgang Nestler; Klaus Freyer; Hanns-Christian Treutler
Management des Produktlebenslaufs
NASA Astrophysics Data System (ADS)
Unternehmen in nachhaltig orientierten Gesellschaften kˆnnen sich nicht mehr nur auf den ˆkonomischen Erfolg beschr‰nken, sondern m¸ssen ebenso die ˆkologischen und sozialen Folgen unternehmerischen Handelns einbeziehen. Als Ausgangspunkt dieser Entwicklung gilt die Konferenz der Vereinten Nationen im Jahr 1992 in Rio de Janeiro. Seither gewinnt eine an den Erfordernissen von ÷kologie, ÷konomie und sozialen Standards ausgerichtete Unternehmenspolitik zunehmend an Bedeutung. Ziel ist das "nachhaltige Unternehmenì. Mit Blick auf Teilprozesse bei der Entwicklung, der Herstellung, der Nutzung und der Entsorgung von Produkten werden lediglich Suboptima bei Wertschˆpfungsprozessen erreicht. Ziel muss es sein, das Gesamtoptimum anzustreben. Dazu m¸ssen k¸nftig alle Akteure im Zusammenhang mit der Entwicklung, der Herstellung, dem Gebrauch und der Entsorgung eines Produktes - also alle Lebenslaufpartner - zusammenarbeiten. Life Cycle Management (LCM) soll den Unternehmen ermˆglichen, technische Produkte und Anlagen zuk¸nftig ¸ber deren gesamten Lebenslauf zu managen, um sowohl negative Umweltwirkungen von Produkten zu minimieren als auch die Wirtschaftlichkeit zu optimieren.
Niemann, Jˆrg; Schuh, G¸nter; Baessler, Elke; Eigner, Martin; Stolz, Marcus; Steinhilper, Rolf; Janusz-Renault, Gabriela; Hieber, Martin
Investigations on the Interaction Between Arcs and Gas Flow Untersuchungen ueber die Wechselwirkung Zwischen Hochstromplasmen und Gasstroemungen in Hochleistungsschaltern.
National Technical Information Service (NTIS)
Model circuit breaker experiments were carried out to investigate the relationship between gas flow and arc behavior in the current zero-region. Synthetic circuits were used for the electrical tests. The optical investigations were carried out by the aid ...
K. Zueckler H. Topplin H. Naecke R. Patzelt K. P. Rolff
Correspondence between Tycho Brahe and Thaddeus Hagecius - the beginnings. (German Title: Briefwechsel zwischen Tycho Brahe und Thaddaeus Hagecius - Anf‰nge)
NASA Astrophysics Data System (ADS)
The voluminous correspondence of Tycho is one of the most interesting sources of the history of astronomy. Nevertheless, it is until today poorly known and rarely cited (Thoren being a counter-example), and a modern critical edition is lacking. Among Tycho Brahe's most frequent correspondents are Wilhelm, the landgrave of Hesse, and his court astronomer Ch. Rothmann. At third place - regarding the number of letters - we find the court physician and astronomer Thaddaeus Hagecius from Prague. Their correspondence lasted from 1575 tpo 1597. This article presents and analyses the most important letters of the Hagecius - Brahe correspondence.
Smolka, Josef
Klinische Nachuntersuchung von implantatgest¸tzten Vollprothesen im zahnlosen und restbezahnten Kiefer ñ ein Vergleich zwischen Teleskopprothesen und den etablierten Stegprothesen
\\u000a SummaryÝÝThe 1-year to 8-year clinical and radiographical results of implants with non-rigid telescopic connectors for overdentures'\\u000a stabilization in comparison with the 1-year to 8-year clinical and radiographical result of implants with bar-retained overdentures\\u000a suggest that both ways of treatment are reliable treatment modalities for the atrophied edentulous jaw. Particularly in geriatric\\u000a patient treatment these concepts provide advantages in terms of
K.-U. Bochdam; K.-U. Benner; T. Holland-Letz; F. Hˆlzle; J. Willer
Zwischen der ÑPhysik des Organischenî und der ÑOrganisierung der Physikî: Ðberlegungen zu Gegenstand und Methode der Biologie
Between Physics of Organism and Organismic Physics: Object and Method of Biology. In the history of biological theory one\\u000a can observe an oscillation between two tendencies of thinking, namely the biologistic and the physicalistic point of view.\\u000a Both aim at a general or unified theory of nature that is relevant for scientific research as well as for philosophical reflection.\\u000a In
Kristian Kˆchy
Gammastrahlenspektrometrische Bestimmung der Aktivit‰tsverh‰ltnisse zwischen Th-228 und seinen Folgeprodukten I. Calculation of the activity ratios from Pulsheight-spectra
Summary A mathematical method is described which allows to calculate the Ra-224 and Pb-212 activities of samples at the time of extirpation or the activity ratios between Th-228 and these both decay products by the variation with time of the Tl-208 activities of extirpated tissue samples containingthorotrast. The variation of the Tl-208 activity of each sample is determined by gammaray-spectrometry
A. Kaul; J. Heyder
Gammastrahlenspektrometrische Bestimmung der Aktivit‰tsverh‰ltnisse zwischen Th-228 und seinen Folgeprodukten II. Calculation of the activity ratios from energy- spectra
Summary A mathematical method is described which allows to determine the Ra-224 and Pb-212 activities of tissue samples containing thorotrast at the time of extirpation from results of gammaray-spectrometry by transformation of the measured pulse height spectra into energy spectra. The activities are calculated from the variation with time of the quantum rate within the 0.24 MeV energy interval. Results
J. Heyder; A. Kaul
Bestrahlungsinduziertes kriechen und schwellen des austenitischen werkstoffes NR. 1.4981 zwischen 400 und 500∞C (RIPCEX I)
NASA Astrophysics Data System (ADS)
ZusammenfassungF¸r den Werkstoff Nr. 1.4981 wurde das bestrahlungsinduzierte Volumenschwellen und Kriechen im Temperaturbereich 400 bis 500∞C bis zu einer Dosis von max. 63 dpa mittels nichtzerstˆrender und zerstˆrender Nachuntersuchungen bestimmt. Dabei zeigte sich eine deutliche Beeinflussung des Volumenschwellens durch eine angelegte Spannung. Das bestrahlungsinduzierte Kriechen wird f¸r den Stahl Nr. 1.4981 durch mindestens zwei Prozesse hervorgerufen, einmal durch den sog. SIPA-Prozess, der auf bevorzugter Absorption von Zwischengitteratomen beruht, zum anderen durch das sog. I-Creep, einem Prozess, der erst nach Einsetzen des Volumenschwellens zum Tragen kommen kann. F¸r hˆhere Dosen liefert letzterer Vorgang den dominierenden Beitrag zum Kriechen.
Herschbach, K.; Schneider, W.; Ehrlich, K.
Beziehungen zwischen den kurzwelligen Strahlungskomponenten auf die horizontale Fl‰che und der Bewˆlkung an ausgew‰hlten Stationen in ÷sterreich
NASA Astrophysics Data System (ADS)
Using the daily sums of the global radiation ( G) at the horizontal surface and the daily means of the amount of clouds ( B), for the four stations Wien, Salzburg, Klagenfurt and Sonnblick the linear and quadratic regressions between G/ G 0 ( G 0 = extraterrestrial radiation) and B were determined by least square method. At the stations Wien, Salzburg and Sonnblick also the regressions between the daily values of H/ G and B ( H = sky radiation) respectively between the daily values of D/ G and B ( D = direct sun radiation) were evaluated. In the verification it is shown, that for the mean conditions by these regressions the daily sums of global radiation, sky radiation and direct sun radiation can be estimated in satisfying manner from cloudiness. Interesting insights in the radiation climatology of Austria are given by statistical analysis of the daily ratios H/ G, D/ G and G/ G 0.
Neuwirth, F.
Konkordanz zwischen Selbst- und Klinikerurteil hinsichtlich depressiver Symptomatik bei Jugendlichen am Beispiel von BDI-II und CDRS-R.
Objectives: Preceding studies demonstrated a high agreement between self-report and clinician's assessment of depression. The concordance on the level of sum scores, subscales, and single items, however, has yet to be investigated in a psychiatric adolescent sample. Also, the influence of additional variables such as age, sex, and IQ has been insufficiently studied in adolescents. Methods: Scores on the BDI-II and CDRS-R, assessed within 1 week, were collected from 105 adolescents (mean age = 15.94 years). Analyses of correlation were done on levels of sum scores, subscales, and single items. Results: There was a high correlation between self-report and clinician's assessment (r = .67). At the level of subscales, items assessing somatic contents demonstrated no higher agreement than did items assessing cognitive and affective contents. The highest agreement at the symptom level was shown for the item assessing suicidal ideations. Additional variables had no significant influence on concordance. Adolescents with a high IQ and outpatient adolescents tended to overestimate their symptoms. Conclusions: The overall correlation was high and did not differ from results of comparable studies of correlations. The highest congruence was shown for the item assessing suicidal ideations, which underlines the accurate assessment of suicidality by clinicians as well. In summary, questionnaires can provide information about the existence of a depressive disorder, although one diagnostic instrument should not be replaced by the other despite a high correlation. PMID:25005902
Straub, Joana; Plener, Paul L; Koelch, Michael; Keller, Ferdinand
Datenkompression, Prozessoptimierung, Aerodynamik: Eine Tour Durch die Skalen
NASA Astrophysics Data System (ADS)
Enorm gestiegene Rechnerkapazit‰ten ermutigen zu einer immer genaueren Erschlieþung komplexer Prozesse in Natur- und Ingenieurwissenschaften durch numerische Simulation. Die Mathematik als Schnittstelle zwischen realer und digitaler Welt liefert einerseits die Grundlagen zur Formulierung notwendigerweise vereinfachter Modelle der Realit‰t. Andererseits bietet sie aber auch die methodischen Grundlagen f¸r den Entwurf effizienter Algorithmen, die aus solchen Modellen quantitative Information gewinnen kˆnnen. Eine zentrale Herausforderung liegt dabei in der Tatsache, dass reale Prozesse meist durch relevante Anteile auf einer riesigen Spannweite von L‰ngenskalen getrieben werden. Die Entwicklung mathematischer Methoden zur Behandlung von Mehrskaligkeit ist daher von wesentlicher Bedeutung. In diesem Artikel wird dies anhand j¸ngster Entwicklungen in ganz unterschiedlichen Anwendungsbereichen erkl‰rt und illustriert, auch um deutlich zu machen, wieviele "Fliegenì man mit einer "mathematischen Klappeì schlagen kann. Insbesondere werden grundlegende, auf Waveletzerlegung beruhende Prinzipien zun‰chst im Rahmen der Bildkompression und -kodierung auf weitgehend elementare Weise erkl‰rt. Es wird dann aufgezeigt, dass diese Konzepte in ganz ‰hnlicher Weise bei der Datenanalyse im Zusammenhang mit verfahrenstechnischen Anwendungen, bei groþskaligen Optimierungsproblemen der Prozessindustrie sowie bei komplexen Strˆmungsproblemen wie in aerodynamischen Anwendungen zum Tragen kommen. Stabile Zerlegungen in Anteile unterschiedlicher L‰ngenskalen erˆffnen dabei einen Zugang zu adaptiven Lˆsungskonzepten, die in der Lage sind, automatisch Rechnerresourcen dort zu plazieren, wo sie zu einer ˆkonomischen Realisierung der gew¸nschten Lˆsungsqualit‰t, etwa in Form von Genauigkeitstoleranzen, benˆtigt werden.
Dahmen, Wolfgang; Marquardt, Wolfgang
Visualization tools for extremely high resolution DEM from the LRO and other orbiter satellites
NASA Astrophysics Data System (ADS)
Recent space missions have included laser altimetry instrumentation that provides precise high-resolution global topographic data products. These products are critical in analyzing geomorphological surface processes of planets and moons. Although highly valued, the high-resolution data is often overlooked by researchers due to the high level of IT sophistication necessary to use the high-resolution data products, which can be as large as several hundred gigabytes. Researchers have developed software tools to assist in viewing and manipulating data products derived from altimetry data, however current software tools require substantial off-line processing, provide rudimentary visualization or are not suited for viewing the new high-resolution data. We have adapted mVTK, a novel software visualization tool, to work with NASA's recently acquired Lunar Reconnaissance Orbiter data. mVTK is a software visualization package that dynamically creates cylindrical cartographic map projections from gridded high-resolution altimetry data in real-time. The projections are interactive 2D shade relief, false color maps that allow the user to make simple slope and distance measurements on the actual underlying high-resolution data. We have tested mVTK on several laser altimetry data sets including binned gridded record data from NASA's Mars Global Surveyor and Lunar Reconnaissance Orbiter space missions.
Montgomery, J.; McDonald, John
Die Erfassung elterlicher Belastung mit dem Eltern- Belastungs-Screening zur Kindeswohlgef‰hrdung (EBSK).
Parental stress is increased in clinical contexts (e.g., child psychiatry) and correlates with behavioral and emotional problems of children. In addition, parental stress can result in a biased parental perception of child's behavior and emotions. These interrelations were examined in a normal (N = 320) and a clinical (N = 75) sample. The "Eltern-Belastungs-Screening zur Kindeswohlgef‰hrdung" (EBSK;
Eichler, Anna K; Glaubitz, Katharina A; Hartmann, Luisa C; Spangler, Gottfried
Ein einzelnes Spaltsinnesorgan auf dem Spinnentarsus: seine Erregung in Abh‰ngigkeit von den Parametern des Luftschallreizes
1.The distal fifth of the tarsi of all walking legs of Cupiennius salei (Labidognatha, Ctenidae) bears several single slit sense organs. One sensory slit on the front of each tarsus is unusual for its large size and constant position. Its long axis runs parallel to that of the tarsus (Figs. 1, 2).2.Impulses can be recorded from this large organ with
Friedrich G. Barth
Tiefengestaffeltes Wasserprobennahmesystem zur spezifischen Beprobung der unges‰ttigten Zone, dem Kapillarsaum und der ges‰ttigten Zone
NASA Astrophysics Data System (ADS)
Flow and transport processes in the transition area between the unsaturated and the saturated zone can influence the quality and properties of the groundwater. Special hydraulic properties have to be considered throughout the entire transition zone, which is a physically and bio-chemically highly active reaction chamber. Using the available measuring techniques, the present processes cannot be fully comprehended or, on the other hand, require significant effort. Thus, the influence of the transition zone is often neglected (Ronen and Sorek, The Unsaturated ZoneóA Neglected Component of Nature. Water Quality Division, Israel Water Commision, Tel-Aviv, 2005). Utilizing laboratory experiments and numerical simulations, an innovative concept for a depth-specific measuring technique was evaluated. Results show that with some modifications of the actual design, the device is capable of sampling the entire transition zone between the unsaturated and the saturated zone, including the capillary fringe, with high temporal and spatial resolution.
Walther, Marc; Fank, Johann; Reimann, Thomas
A Combined DEM/FEM Multiscale Method and Structure Failure Simulation under Laser Irradiation
Analysis of a variety of engineering problems requires computation at different length scales. A combined discrete/finite element numerical method is proposed and developed in this paper to meet this requirement. This method performs discrete element method at meso-scale to reach necessary precision, and finite element method at macro-scale to save the computation time and cost. The key point for this method is to define a special transition layer between discrete element zone and the finite element zone. We apply this new method to simulate the failure responses of a pre-stressed aluminum plate and a cylindrical shell with inner pressure under laser irradiation with the combination codes of DM3 (a 3D Discrete Meso-Element Dynamic Method)/plane FEM and DM3/shell FEM developed in this lab, respectively. It finds good agreement between the current computational results and the reported results in the references.
Tang Zhiping; Xu Jianlong [Key Laboratory for Mechanical Behavior and Design of Materials (LMBD), University of Science and Technology of China, Hefei 230026 (China)
DEM-based deterministic landslide hazard analysis in the Lesser Himalaya of Nepal
In Nepal, people live in widely spread settlements in the fragile Himalayan terrains, and suffer more from landslides than from any other type of natural disaster. The small-scale rainfall-triggered landslides in the Lesser Himalaya of Nepal are generally shallow (about 0.5 to 2.5 m) and are triggered by changes in the physical property of soil layers during rainfall. The relation
R. K. Dahal; S. Hasegawa; A. Nonomura; M. Yamanaka; S. Dhakal
Radio-continuum study of MCSNR J0536-7038 (DEM L249)
NASA Astrophysics Data System (ADS)
We present a detailed radio-continuum study on Australia Telescope Compact Array (ATCA) observations of Large Magellanic Cloud (LMC) supernova remnant (SNR), MCSNR J0536-7038. This Type Ia SNR follows a horseshoe morphology, with a size 32 pc ◊ 32 pc (1-pc uncertainty in each direction). It exhibits a radio spectrum ?=-0.52±0.07 between ?=73 and 6 cm. We report detections of regions showing moderately high fractional polarisation at 6 cm, with a peak value of 71±25 % and a mean fractional polarisation of 35±8 %. We also estimate an average rotation measure across the remnant of -237 rad m-2. The intrinsic magnetic field appears to be uniformly distributed, extending in the direction of the two brightened limbs of the remnant.
Bozzetto, L. M.; Filipovi?, M. D.
Structural Analysis of Central Luzon, Philippines, Using Shuttle Radar Topography Mission DEM
NASA Astrophysics Data System (ADS)
Central Luzon Island (13-16∞N, 120-122∞E), which is bounded to the east by Philippine Trench, to the west by Manila Trench, to the north by Digdig-Dingalan Fault (DDF) and to the south by Verde Island Passage Fault (VIPF), is one of the most seismically and volcanologically active regions in the Philippines. Active seismicity and violent earthquakes in the region are evidently related to the activities along the subduction zones and branches of the Philippine Fault system. Volcanic eruptions and periodic swarms of volcanic earthquakes were also observed in three active volcanoes, i.e., Pinatubo, Taal Volcano Island and Banahaw, while young calderas of Taal and Laguna de Bay are demonstrably fault-bounded. We use the Shuttle Radar Topography Mission (SRTM) data with 90 m spatial resolution to conduct regional mapping of the faults and volcanic structures in this region. Of particular interests are the NE-SW set of normal faults within the Macolod Corridor, the right-lateral Marikina Valley Fault System (MVFS), the prevalence of N-S trending structures and the series of NW-SE structures that parallel to sub-parallel the active branches of the Philippine Fault. Using ENVI software package, we processed the SRTM data into shaded relief images and examined the lineament features from different azimuth directions and angles of artificial illumination. The prominent NW-SE structures in this area revealed by SRTM data were formed as sinistral shears that parallel the seismically active DDF and VIPF. The N-S trending structures, including some segments of MVFS and N-S oriented fold axes, were apparently generated by an earlier E-W compression, but recently displayed dextral movement with localized vertical component and pull-apart zones. The overprinting of recent fault kinematics on previously formed structures suggest a dramatic shift of regional stress distribution in Central Luzon. The dextral movement along MVFS and the extensional NE-SW faults within the Macolod Corridor are consistent with the regional deformation due to coupling of DDF and VIPF movements. Similarly, the E-W to ENE-WSW and N-S to NNE-SSW structures probably formed as Riedel and anti-Riedel shears.
Torres, R.; Mouginis-Mark, P.; Garbeil, H.; Bautista, L.; Ramos, E.
Elementquerstˆrungen bei der spurenanalytischen Selen-Bestimmung nach dem Hydrid-AAS-Verfahren
The sodium boro hydride-reduction method for the liberation of selenium from acid sample solutions in connection with its determination by AAS using a heatable optical cell made of quartz (hydride system MHS-1, Bodenseewerk Perkin-Elmer, Ðberlingen, F.R.G.) is interfered with by numerous concomitant elements occurring even in the trace range in the sample solution.
A. Meyer; Ch. Hofer; G. Tˆlg; S. Raptis; G. Knapp
Numerical simulation of grate firing systems using a coupled CFD\\/discrete element method (DEM)
The objective of this study is to simulate the motion and chemical conversion of solid fuels in a packed bed moving on a forward acting grate. The approach considers a packed bed to be composed of a large number of individual (currently spherical) particles, which have different properties and sizes. Each of these particles undergoes a sequence of processes such
E. Simsek; B. Brosch; S. Wirtz; V. Scherer; F. Kr¸ll
Experimentelle Untersuchungen zum Stockwachstum und zur Medusenbildung bei dem marinen Hydrozoon Eirene viridula
The development of both slide-grown and non-substrate bound colonies ofE. viridula (Thecata-Leptomedusae) ranging in size from 1 to 50 hydranths was investigated under various temperature conditions. The majority of slide-grown colonies reached a larger final size than non-substrate bound ones, in 20∞, 25∞ and 29∞ C. Raising the temperature did not stimulate propagation of hydranths as expected. Most of the
M. Bierbach; D. K. Hofmann
Effect of the impact angle on the breakage of agglomerates: a numerical study using DEM
The study of agglomerate strength is of vital importance in several industrial applications such as pharmaceutical, detergent and food manufacturing. Agglomerates could experience a size reduction during the production and handling processes due to collisions with other agglomerates or with the moving components and walls as well as during bulk flow due to shear deformation. In this analysis, we focus
R. Moreno; M. Ghadiri; S. J. Antony
Lasergestutzte Kristallzucht Nach Dem Zonenschmelzverfahren (Float Zone Crystal Growth Using Laser Radiation).
National Technical Information Service (NTIS)
A float zone crystal growth apparatus was developed and built. To evaluate the influences of different laser wavelengths on crystal growth, the molten zone was heated either by CO2 (10 micrometers) or CO (5 micrometers) laser radiation. Transparent single...
J. Muckenschnabel U. Becker U. Brauch A. Cohen
Estimating Water Storage in Prairie Wetlands from a LiDAR DEM
The Prairie Pothole Region (PPR) of North America contains millions of wetlands in shallow depressions that have potential to store a significant volume of surface water. Assessing and modeling the effect of wetland storage on streamflow requires accurate methods to quantify wetland water volume. Currently, many methods rely on utilizing the strong statistical relationships between area (A), volume (V), and
C. J. Westbrook; A. G. Minke; J. W. Pomeroy; X. Guo
Accurate DEM Reconstruction from Permanent Scatterers and Multi-baseline Interferometry
The application of the Permanent Scatterers (PS) Technique in multi-temporal data-sets, namely the identification and exploitation of sparse coherent targets, has shown that it is possible to estimate and remove interferometric phase components due to atmospheric effects and orbital fringes. So far, the application of the PS technique has been focused on the extraction of the motion field of the
Alessandro Parizzi; Daniele Perissin; Claudio Prati; Fabio Rocca; Alessandro Ferretti
Neue Erkenntnisse auf dem Gebiete der Parasitologie und der parasit‰ren Erkrankungen des Menschen
NASA Astrophysics Data System (ADS)
The increasing interest in the parasites of man in the Federal Republic of Germany is connected with the unbounded keenness of German people to travel. They favor southern regions with warm climates which are usually infested with parasites. Thus the general practitioner is nowadays confronted in his daily routine with ìimportedî pathogenic organisms and diseases as yet unknown to him or with which he need not have reckoned in the past. Furthermore, new information now exists on the development of well-known parasites of our regions, which can be pathogenic to man. Fortunately, new reliable drugs have come on the market, rendering some parasitic diseases harmless.
Piekarski, G.
Geocoding of fast-delivery ERS-l SAR image mode product using DEM data
An algorithm for geocoding and radiometric correction of ERSñ1 Synthetic Aperture Radar images by using Digital Elevation Model data is described a.nd applied to images over a mountainous area in Norway. Several images covering the same area are calibrated and geocoded into a UTM map projection and the results are evaluated against map and i\\/1 situ measurements. The map to
H. Johnsen; L. Lauknes; T. Guneriussen
Multifractal analysis applied to the study of the accuracy of DEM-based stream derivation
NASA Astrophysics Data System (ADS)
A correct description of river network morphology is very important when it is used to study different features of a river's morphology as well as phenomena related to it, such as erosion, nitrogen retention or sediment pollution. In recent years, different algorithms have been developed to extract drainage networks directly from Digital Elevation Models. In this paper, the suitability of ArcHydro extension, developed for ArcGIS Desktop and based on the D8 algorithm to generate river networks has been studied by using multifractal analysis. The river networks generated by ArcHydro tools were compared to those provided by photogrammetric restitution for different flow accumulation threshold values. One limitation of the D8 algorithm in order to generate the most appropriate river networks is the correct choice of the flow accumulation threshold value. Multifractal analysis has shown itself to be an efficient approach to determine the most suitable flow accumulation threshold values. Moreover, this approach has allowed characterizing the morphology of river networks and testing the quality of ArcHydro results. According to the multifractal spectra, the main difference between the networks considered here is the lesser stream density with a low channel order detected for ArcHydro results compared to photogrammetric restitution. In addition, the relationship between ruggedness number for the largest contributing area and fractal dimensions in each study area has been explored. The use of multifractal analysis has been extended to drainage network simulation going beyond the descriptive aim of previous works.
Ariza-Villaverde, A. B.; JimÈnez-Hornero, F. J.; GutiÈrrez de RavÈ, E.
Simulations of Fracture and Fragmentation of Geologic Materials using Combined FEM\\/DEM Analysis
Results are presented from a study investigating the effect of explosive and impact loading on geological media using the Livermore Distinct Element Code (LDEC). LDEC was initially developed to simulate tunnels and other structures in jointed rock masses with large numbers of intact polyhedral blocks. However, underground structures in jointed rock subjected to explosive loading can fail due to both
J P Morris; M B Rubin; G I Block; M P Bonner
Simulations of fracture and fragmentation of geologic materials using combined FEM\\/DEM analysis
Results are presented from a study investigating the effect of explosive and impact loading on geological media using the Livermore distinct element code (LDEC). LDEC was initially developed to simulate tunnels and other structures in jointed rock masses with large numbers of intact polyhedral blocks. However, underground structures in jointed rock subjected to explosive loading can fail due to both
J. P. Morris; M. B. Rubin; G. I. Block; M. P. Bonner
Dynamic simulations of geological materials using combined FEM\\/DEM\\/SPH analysis
An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geological materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such
Joseph Morris; Scott Johnson
Dynamic simulations of geologic materials using combined FEM\\/DEM\\/SPH analysis
An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geologic materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such
J P Morris; S M Johnson
From bifurcation to failure in a granular material: a DEM analysis
The question of diffuse failure in granular media such as soils is treated by numerical modelling with a discrete element\\u000a model. Two numerical samples are considered, one dense and the other loose. A criterion based on the sign of the second-order\\u000a work is applied to the numerical model to detect bifurcation points related to diffuse failure. The notions of loss
L. Sibille; F.-V. DonzÈ; F. Nicot; B. Chareyre; F. Darve