text:
Office of Scientific and Technical Information
Carderock Large Cavitation Tunnel | Open Energy Information
Open Energy Info (EERE)
Large Cavitation Tunnel Large Cavitation Tunnel Jump to: navigation, search Basic Specifications Facility Name Carderock Large Cavitation Tunnel Overseeing Organization United States Naval Surface Warfare Center Hydrodynamic Testing Facility Type Tunnel Length(m) 13.1 Beam(m) 3.0 Depth(m) 3.0 Water Type Freshwater Cost(per day) Contact POC Special Physical Features The Large Cavitation Channel was designed as a variable pressure, recirculating, cavitation tunnel with a very low acoustic background level; test section pressure: 3.5-414 kPa (0.03 to 4 atmospheres, 0.5 to 60 psia); air content: 10% to 100% saturation Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Velocity(m/s) 18 Recirculating Yes Wind Capabilities
Carderock 2-ft Variable Pressure Cavitation Water Tunnel | Open Energy
2-ft Variable Pressure Cavitation Water Tunnel 2-ft Variable Pressure Cavitation Water Tunnel Jump to: navigation, search Basic Specifications Facility Name Carderock 2-ft Variable Pressure Cavitation Water Tunnel Overseeing Organization United States Naval Surface Warfare Center Hydrodynamic Testing Facility Type Tunnel Beam(m) 0.6 Depth(m) 0.6 Water Type Freshwater Cost(per day) Contact POC Special Physical Features The 2-Foot Variable Pressure Cavitation Water Tunnel is a vertical plane, closed recirculating, variable-speed, variable-pressure, open jet test section, closed jet test section, and semi-rectangular test section. Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 17 Recirculating Yes
Carderock 3-ft Variable Pressure Cavitation Water Tunnel | Open Energy
Variable Pressure Cavitation Water Tunnel Variable Pressure Cavitation Water Tunnel Jump to: navigation, search Basic Specifications Facility Name Carderock 3-ft Variable Pressure Cavitation Water Tunnel Overseeing Organization United States Naval Surface Warfare Center Hydrodynamic Testing Facility Type Tunnel Beam(m) 0.7 Depth(m) 0.7 Water Type Freshwater Cost(per day) Contact POC Special Physical Features The 3-ft Variable Pressure Cavitation Water Tunnel is a vertical plane, closed recirculating with resorber, variable-speed, variable-pressure, two interchangeable circular test sections. Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 25.8 Recirculating Yes Wind Capabilities Wind Capabilities None
Penn Large Water Tunnel | Open Energy Information
Penn Large Water Tunnel Penn Large Water Tunnel Jump to: navigation, search Basic Specifications Facility Name Penn Large Water Tunnel Overseeing Organization Pennsylvania State University Hydrodynamics Hydrodynamic Testing Facility Type Tunnel Length(m) 4.3 Beam(m) 1.2 Depth(m) 1.2 Water Type Freshwater Cost(per day) Contact POC Special Physical Features Closed loop; Turbulence level = 0.1%; Pressure range = 3-60psi; Controlled cavitation = # >0.1; Control Air content = >1ppm per mole Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 16.8 Recirculating Yes Pressure Range(Psi) 3 - 60 Wind Capabilities Wind Capabilities None Control and Data Acquisition Description National Instruments steady 24 bit
Cavitation Erosion
Science Conference Proceedings (OSTI)
Oct 30, 2013 ... Advances in Hydroelectric Turbine Manufacturing and Repair: Cavitation Erosion Sponsored by: Metallurgical Society of the Canadian Institute�...
Property:Channel/Tunnel/Flume | Open Energy Information
Channel/Tunnel/Flume Channel/Tunnel/Flume Jump to: navigation, search Property Name Channel/Tunnel/Flume Property Type String Pages using the property "Channel/Tunnel/Flume" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + Yes + 10-ft Wave Flume Facility + Yes + 11-ft Wave Flume Facility + None + 2 2-ft Flume Facility + Yes + 3 3-ft Wave Flume Facility + None + 5 5-ft Wave Flume Facility + Yes + 6 6-ft Wave Flume Facility + Yes + A Alden Large Flume + Yes + Alden Small Flume + Yes + Alden Tow Tank + None + Alden Wave Basin + None + B Breakwater Research Facility + None + Bucknell Hydraulic Flume + Yes + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + Yes + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + Yes +
Vacuum gaps with small tunnel currents at large electric field...
NLE Websites -- All DOE Office Websites (Extended Search)
gap can help to reduce tunnel currents. We discuss applications of this technology for energy storage, charge storage, and power supplies. Speaker Bio: Professor Alfred Hubler...
MHL High Speed Cavitation | Open Energy Information
High Speed Cavitation High Speed Cavitation Jump to: navigation, search Basic Specifications Facility Name MHL High Speed Cavitation Overseeing Organization University of Michigan Hydrodynamics Hydrodynamic Testing Facility Type Channel Length(m) 0.8 Beam(m) 0.2 Depth(m) 0.2 Cost(per day) $2000(+ Labor/Materials) Towing Capabilities Towing Capabilities Yes Maximum Velocity(m/s) 25.9 Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 25.9 Recirculating No Wind Capabilities Wind Capabilities None Control and Data Acquisition Description Custom Data Acquisition System using National Instruments hardware; system compatible with Planing Hull and Floating Beam Dynamometers Number of channels 16 Bandwidth(kHz) 20 Cameras Yes
Vacuum gaps with small tunnel currents at large electric field and its
Vacuum gaps with small tunnel currents at large electric field and its Vacuum gaps with small tunnel currents at large electric field and its potential applications for energy storage, charge storage and power supplies. Friday, May 27, 2011 - 4:00pm SSRL Conference Room 137-226 Alfred Hubler, Department of Physics, University of Illinois, Urbana-Champaign We study tunnel currents and electric break down in vacuum gaps experimentally and theoretically. We find that electric field at break down in nano vacuum gaps is 3 order of magnitude larger than in macroscopic capacitors. Pointed electrodes increase the limiting field even further. Eigen states in the gap can help to reduce tunnel currents. We discuss applications of this technology for energy storage, charge storage, and power supplies. Speaker Bio: Professor Alfred Hubler is the director of the Center for
Wind Tunnel Measurements of the Response of Hot-Wire Liquid Water Content Instruments to Large Droplets
Wet wind tunnel tests were performed on more than 23 cloud liquid water content (LWC) probes and drop spectrometers at the NASA Icing Research Tunnel, with a main objective to characterize their response to large-droplet conditions. As a part of ...
J. W. Strapp; J. Oldenburg; R. Ide; L. Lilie; S. Bacic; Z. Vukovic; M. Oleskiw; D. Miller; E. Emery; G. Leone
E-Print Network (OSTI)
Yellowfin tuna (Thunnus albacares) swimming kinematics was studied in a large water tunnel at controlled swimming velocities (U). Quantified kinematic variables included the tail-beat frequency, stride length (l), caudal amplitude, yaw, the propulsive wavelength, the speed of the propulsive wave (C) and the sweepback angle of the pectoral fins. In general, all variables, except the propulsive wavelength and consequently C, are comparable to values determined for other teleosts. The propulsive wavelength for the tunas (1.23�1.29L, where L is fork length) is 30�60 % longer than in other cruise-adapted teleosts such as salmonids. The resulting thunniform swimming mode and the morphological and anatomical adaptations associated with the long propulsive wavelength (e.g. fusiform body shape, rigid vertebral column) act to minimize anterior resistance and maximize caudal thrust. The long propulsive wavelength also increases the maximum l which, in concert with the elevated muscle temperatures of tunas, increases their maximum swimming velocity.
Iii Kinematics; Heidi Dewar; Jeffrey; B. Graham
The metabolic rates (V ? O?) of three tropical tunas [yellowfin tuna (Thunnus albacares), kawakawa (Euthynnus affinis) and skipjack (Katsuwonus pelamis)] were estimated using a large water-tunnel respirometer. Experiments lasting up to 31 h were used to determine the effects of velocity (U) on tuna V ? O ? over a range of U (17?150 cm s ?1) and temperatures (18�30 ?C). Replicate tests were carried out on several fish. The swimming V ? O ? of yellowfin is temperature-dependent (Q10=1.67, determined over intervals of 3�5 ?C). For yellowfin and skipjack, it was also possible to partition metabolic costs between maintenance and locomotion. The standard metabolic rate (SV ? O?) was estimated by extrapolation of the U/V ? O ? function to U=0. Comparisons of SV ? O ? for different size groups of yellowfin show that the mass-specific scaling exponent for V ? O ? is ?0.40. The SV ? O ? of tuna is comparable to values determined previously by stasis respirometry and is approximately three times higher than that of salmonids. Further comparisons with salmonids show that the slope of the U/V ? O ? function is less for tunas, which demonstrate a greater swimming efficiency.
I. Energetics; Heidi Dewar; Jeffrey; B. Graham
Studies of tropical tuna swimming performance in a large water tunnel
The body temperatures (Tb) of nine yellowfin tuna (Thunnus albacares) were monitored while fish swam in a large water tunnel at controlled velocities (U) and ambient temperatures (Ta). Monitoring Tb during step changes in Ta at constant U permitted estimation of the thermal rate coefficient (k), an index of heat transfer. In the yellowfin, k is dependent on both Ta and the direction of the thermal gradient (i.e. whether Ta is greater or less than Tb). Modulation of k in response to Ta was further demonstrated during tests in which U was varied; the elevation of Tb in response to equal increases in U was 3�4 times less at 30 ?C than at 25 and 20 ?C. These experiments demonstrate that the yellowfin tuna can modulate heat transfer. This ability could prevent overheating during intense activity, retard heat loss during a descent into cool water and permit increased heat gain upon returning to warm surface waters (i.e. when Tb Heidi Dewar; Jeffrey B. Graham; Richard; W. Brill 1994-01-01T23:59:59.000Z
Heidi Dewar; Jeffrey B. Graham; Richard; W. Brill
A Wind Tunnel Investigation on the Riming of Snowflakes. Part I: Porous Disks and Large Stellars
The effects of porosity on the accretional growth characteristics of ice crystal aggregates (snowflakes) are investigated by riming circular disks of ice in a cloud tunnel. Twelve disk models were used, sized 5 to 6 mm and 10 to 11 mm in diameter,...
Jeffrey K. Lew; Derek C. Montague; Hans R. Pruppacher; Roy M. Rasmussen
Large energy gaps in CaC{sub 6} from tunneling spectroscopy : possible evidence of strong-coupling superconductivity.
Tunneling in CaC{sub 6} crystals reproducibly reveals superconducting gaps {Delta} of 2.3 {+-} 0.2 meV that are {approx}40% larger than reported earlier. In an isotropic s-wave scenario, that puts CaC{sub 6} into the class of very strongly coupled superconductors, since 2{Delta}/kT{sub c}-4.6, implying that soft Ca phonons are primarily involved in the superconductivity. This conclusion explains the relatively large Ca isotope effect found recently for CaC{sub 6}, but it could also signal a strong anisotropy in the electron-phonon interaction.
Kurter, C.; Ozyuzer, L.; Mazur, D.; Zasadzinski, J. F.; Rosenmann, D.; Claus, H.; Hinks, D. G.; Gray, K. E.; Materials Science Division; Illinois Inst. of Tech.; Izmir Inst. of Tech.
Penn Small Water Tunnel | Open Energy Information
Water Tunnel Water Tunnel Jump to: navigation, search Basic Specifications Facility Name Penn Small Water Tunnel Overseeing Organization Pennsylvania State University Hydrodynamics Hydrodynamic Testing Facility Type Tunnel Length(m) 0.8 Beam(m) 0.3 Depth(m) 0.3 Water Type Freshwater Cost(per day) Contact POC Special Physical Features Closed loop; Turbulence level = 0.1%; Pressure range = 3-60psi; Controlled cavitation = # >0.1; Control Air content = >1ppm per mole Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 21 Recirculating Yes Pressure Range(Psi) 3 - 60 Wind Capabilities Wind Capabilities None Control and Data Acquisition Description National Instruments dynamic analyzer, 24-bit
Cavitation-Induced Fusion: Proof of Concept
Cavitation-induced fusion (also known as bubble fusion or sonofusion) has been a topic of much debate and controversy and is generally (albeit incorrectly) perceived as unworkable. In this paper we present the theoretical foundations of cavitation-induced fusion and summarize the experimental results of the research conducted in the past 20 years. Based on the systematic study of all available data we conclude that the cavitation-induced fusion is feasible, doable, and can be used for commercial power generation. We present the results of our own research and disclose a commercial reactor prototype.
Fomitchev-Zamilov, Max I
Max I. Fomitchev-Zamilov
In this chapter we briefly evaluate the effects of cavitation on the gas-liquid-solid ..... synthesis of A-type zeolites by enabling cheap natural minerals such as kaolin to ..... the aldehyde substrate is adsorbed, whereas under sonochemical�...
11 PFLOP/s simulations of cloud cavitation collapse
We present unprecedented, high throughput simulations of cloud cavitation collapse on 1.6 million cores of Sequoia reaching 55% of its nominal peak performance, corresponding to 11 PFLOP/s. The destructive power of cavitation reduces the lifetime of ...
Diego Rossinelli, Babak Hejazialhosseini, Panagiotis Hadjidoukas, Costas Bekas, Alessandro Curioni, Adam Bertsch, Scott Futral, Steffen J. Schmidt, Nikolaus A. Adams, Petros Koumoutsakos
Cavitation descaling techniques for geothermal applications
SciTech Connect
A simple and more efficient technique for descaling hard silica scales is urgently needed in order to exploit geothermal energy resources economically. With this objective in mind, DAEDALEAN ASSOCIATES, Incorporated is engaged in a research and development program utilizing the phenomenon of cavitation for cleaning and descaling under the sponsorship of ERDA, Division of Geothermal Research. The highlights of the research carried out so far under this program is reviewed in this presentation. Various effects of the phenomenon of cavitation erosion are presented. The intensity of cavitation erosion and its use in descaling applications are explained. The parameters governing the intensity of erosion are discussed. The overall objectives of the program are to demonstrate the engineering feasibility of utilizing cavitation and to generate engineering design data for its application in geothermal technology. The test facility used for this research consists of flow equipment, test chamber, and associated instrumentation. The performance of cavitating nozzles have been evaluated over a range of sizes. The intensity of erosion for one specific nozzle has been measured. The cleaning rates, the quality of cleaned surface and the intensity margin available so as not to damage the pipe wall have been determined for this specific design. Further work is under progress.
Thiruvengadam, Alagu P.
Twin boundary cavitation in aged type 304 stainless steel
A transition from grain to twin boundary cavitation was observed in aged- and-creep-tested type 304 stainless steel. Evidence of twin boundary cavitation has also been observed for unaged material under certain test conditions. This same behavior was also found in aged type 316 stainless steel. Several possible reasons have been suggested for the absence of frequently observed grain boundary cavitation. (auth)
Sikka, V.K.; Swindeman, R.W.; Brinkman, C.R.
Throttled Valve Cavitation and Erosion
The submitted manuscipt has been authored by a contmrctor of the US. Government under contract No. DE-AC05-840R21400. Accordingly, the U. S. Government retains a nonexclusive royalty-free license to publish or reproduce the published form of the contribution, or aflow others to do so, for US. Government pupose & 1. Background In November of 1988, Brunswick plant maintenance personnel discovered significant localized erosion of the valve body of a Unit I Residual Heat Removal (RHR) valve, 1-El 1-F017B (the maintenance was being performed to repair the valve stem and back seat). 1 The F017B valv'e is a 20-inch Rockwell angle globe valve that has been historically used to throttle RHR flow. Excessive throttling of the valve had resulted in cavitation-induced erosion damage to areas immediately downstream of the seat. Subsequent investigation indicated that erosion of valve bodies was a generic concern for the other RHR valves used in the same service (FO17A on Unit I and F017A and F017B on Unit 2). Brunswick personnel expanded the investigation to include another set of RHR valves that had also been used in throttling service. The F024A and F024B valves (from both Units), which are used for Suppression Pool Cooling, were also found to have been damaged by
Don Casada; Don Casada
Molecular Dynamics Simulation of Cavitation in Metallic Glass
We have undertaken a series of molecular dynamics simulations of cavitation under hydrostatic tension in a binary metallic glass analog using pair-wise�...
Hydrogen Attack in Creeping Polycrystals Due to Cavitation on ...
Sep 1, 1994 ... Hydrogen Attack (HA) is the development at elevated temperatures of grain boundary cavitation by internal methane gas, which is generated by�...
W-11: Combined Cavitation and Particle Erosion of Brass
A novel method is employed that combines the effect of particle erosion and cavitation erosion, in order to test brass under laboratory conditions. Triangular�...
Predominantly Superconducting Origin of Large Energy Gaps in Underdoped Bi{sub 2} Sr{sub 2} CaCu{sub 2 }O{sub 8+ {delta}} from Tunneling Spectroscopy
New tunneling data are reported in Bi{sub 2}Sr {sub 2}CaCu{sub 2}O{sub 8+{delta}} which show quasiparticle excitation gaps, {Delta}, reaching values as high as 60thinspthinspmeV for underdoped crystals with T{sub c}=70 K . These energy gaps are nearly 3thinspthinsptimes larger than those of overdoped crystals with similar T{sub c} . Despite the large differences in gap magnitude, the tunneling spectra display qualitatively similar characteristics over the entire doping range. Detailed examination of the spectra, including the Josephson I{sub c}R{sub n} product measured in break junctions, indicates that these energy gaps are predominantly of superconducting origin. {copyright} {ital 1999} {ital The American Physical Society}
Miyakawa, N.; Zasadzinski, J.F.; Ozyuzer, L.; Guptasarma, P.; Hinks, D.G.; Gray, K.E. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Miyakawa, N. [Department of Applied Physics, Science University of Tokyo, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601 (Japan)] [Department of Applied Physics, Science University of Tokyo, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601 (Japan); Zasadzinski, J.F. [Illinois Institute of Technology, Chicago, Illinois 60616 (United States)] [Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Ozyuzer, L. [Department of Physics, Izmir Institute of Technology, TR-35230 Izmir (Turkey)] [Department of Physics, Izmir Institute of Technology, TR-35230 Izmir (Turkey); Kendziora, C. [Naval Research Laboratory, Washington, D.C. 20375 (United States)] [Naval Research Laboratory, Washington, D.C. 20375 (United States)
Flatback airfoil wind tunnel experiment.
DOE Green Energy (OSTI)
A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.
Mayda, Edward A. (University of California, Davis, CA); van Dam, C.P. (University of California, Davis, CA); Chao, David D. (University of California, Davis, CA); Berg, Dale E.
A study of the measurement of cavitation inception using an electrostatic technique
A new concept for detecting cavitation inception has been studied experimentally. In this exploratory study, cavitation is generated by varying the flow velocity and pressure around a circular cylinder. Cavitation inception has been detected by sensing the natural charges and electrification generated during cavitation. The agreement between visual determination and detection using electrostatic probes was quite good. The background and possible mechanisms are reviewed and discussed.
Yuecan, T. (Science and Technology, Wuhan); Velkoff, M.R.
Tunnel magnetoresistance in epitaxially grown magnetic tunnel junctions using Heusler alloy electrode and MgO barrier
Epitaxially grown magnetic tunnel junctions (MTJs) with a stacking structure of Co{sub 2}MnSi/MgO/CoFe were fabricated. Their tunnel magnetoresistance (TMR) effects were investigated. The TMR ratio and tunnelling conductance characteristics of MTJs were considerably different between those with an MgO barrier prepared using sputtering (SP-MTJ) and those prepared using EB evaporation (EB-MTJ). The EB-MTJ exhibited a very large TMR ratio of 217% at room temperature and 753% at 2 K. The bias voltage dependence of the tunnelling conductance in the parallel magnetic configuration for the EB-MTJ suggests that the observed large TMR ratio at RT results from the coherent tunnelling process through the crystalline MgO barrier. The tunnelling conductance in the anti-parallel magnetic configuration suggests that the large temperature dependence of the TMR ratio results from the inelastic spin-flip tunnelling process.
Tsunegi, S.; Sakuraba, Y.; Oogane, M.; Telling, N. D.; Shelford, L. R.; Arenholz, E.; van der Laan, G.; Hicken, R. J.; Takanashi, K.; Ando, Y.
Chemical Applications of Electrohydraulic Cavitation for Hazardous Waste Control
We have been investigating the fundamental chemistry and physics underlying the application of electrohydraulic cavitation as induced by pulsed-power plasma discharge in water, by spark-gap discharge in water (i.e., lithotripsy) and by pulsed (and/or continuous) ultrasonic irradiation (i.e., sonolysis) of water for the elimination of chlorinated hydrocarbons from water. These three different applications of electric power share a common physical thread, which involves hydraulic cavitation, production of shock waves, release of high energy light, production of hydroxyl radicals, hydrogen atoms, hydrogen peroxide and aquated electrons. The chemical changes of compounds in water pulsed with these different sources of power are induced in part by the violent collapse of cavitation bubbles.
Hoffmann, M. R.
Cavitation contributes substantially to tensile creep in silicon nitride
During tensile creep of a hot isostatically pressed (HIPed) silicon nitride, the volume fraction of cavities increases linearly with strain; these cavities produce nearly all of the measured strain. In contrast, compressive creep in the same stress and temperature range produces very little cavitation. A stress exponent that increases with stress ({dot {var_epsilon}} {proportional_to} {sigma}{sup n}, 2 < n < 7) characterizes the tensile creep response, while the compressive creep response exhibits a stress dependence of unity. Furthermore, under the same stress and temperature, the material creeps nearly 100 times faster in tension than in compression. Transmission electron microscopy (TEM) indicates that the cavities formed during tensile creep occur in pockets of residual crystalline silicate phase located at silicon nitride multigrain junctions. Small-angle X-ray scattering (SAXS) from crept material quantifies the size distribution of cavities observed in TEM and demonstrates that cavity addition, rather than cavity growth, dominates the cavitation process. These observations are in accord with a model for creep based on the deformation of granular materials in which the microstructure must dilate for individual grains t slide past one another. During tensile creep the silicon nitride grains remain rigid; cavitation in the multigrain junctions allows the silicate to flow from cavities to surrounding silicate pockets, allowing the dilation of the microstructure and deformation of the material. Silicon nitride grain boundary sliding accommodates this expansion and leads to extension of the specimen. In compression, where cavitation is suppressed, deformation occurs by solution-reprecipitation of silicon nitride.
Luecke, W.E.; Wiederhorn, S.M.; Hockey, B.J.; Krause, R.F. Jr.; Long, G.G. [National Institute of Standards and Technology, Gaithersburg, MD (United States)
Extreme conditions during multibubble cavitation: Sonoluminescence as a spectroscopic probe
Cavitation MBSL Plasma a b s t r a c t We review recent work on the use of sonoluminescence (SL) to probe to $9000 K. The effective pressure during MBSL is $300 bar, based on atomic line shifts. Given nanosecond in a liquid, which can create extreme conditions in localized, short- lived hot spots. During the past few
Zimmerman, Steven C.
Tunnel closure calculations
When a deeply penetrating munition explodes above the roof of a tunnel, the amount of rubble that falls inside the tunnel is primarily a function of three parameters: first the cube-root scaled distance from the center of the explosive to the roof of the tunnel. Second the material properties of the rock around the tunnel, and in particular the shear strength of that rock, its RQD (Rock Quality Designator), and the extent and orientation of joints. And third the ratio of the tunnel diameter to the standoff distance (distance between the center of explosive and the tunnel roof). The authors have used CALE, a well-established 2-D hydrodynamic computer code, to calculate the amount of rubble that falls inside a tunnel as a function of standoff distance for two different tunnel diameters. In particular they calculated three of the tunnel collapse experiments conducted in an iron ore mine near Kirkeness, Norway in the summer of 1994. The failure model that they used in their calculations combines an equivalent plastic strain criterion with a maximum tensile strength criterion and can be calibrated for different rocks using cratering data as well as laboratory experiments. These calculations are intended to test and improve the understanding of both the Norway Experiments and the ACE (Array of conventional Explosive) phenomenology.
Moran, B.; Attia, A.
Regular Scanning Tunneling Microscope Tips can be Intrinsically Chiral
We report our discovery that regular scanning tunneling microscope tips can themselves be chiral. This chirality leads to differences in electron tunneling efficiencies through left- and right-handed molecules, and, when using the tip to electrically excite molecular rotation, large differences in rotation rate were observed which correlated with molecular chirality. As scanning tunneling microscopy is a widely used technique, this result may have unforeseen consequences for the measurement of asymmetric surface phenomena in a variety of important fields.
Tierney, Heather L.; Murphy, Colin J.; Sykes, E. Charles H. [Department of Chemistry, Tufts University, Medford, Massachusetts 02155-5813 (United States)
Superconductivity and electron tunneling
Experiments on the tunneling of electrons through a thin dielectric layer separating two superconducting metals are reported. Data are presented for the pairs AI-Pb, Sn-Pb, and In-Sn. Particular attention is paid to the form of the tunneling current ...
S. Shapiro; P. H. Smith; J. Nicol; J. L. Miles; P. F. Strong
Cavitation and two-phase flow characteristics of SRPR (Savannah River Plant Reactor) pump. Final report
The possible head degradation of the SRPR pumps may be attributable to two independent phenomena, one due to the inception of cavitation and the other due to the two-phase flow phenomena. The head degradation due to the appearance of cavitation on the pump blade is hardly likely in the conventional pressurized water reactor (PWR) since the coolant circulating line is highly pressurized so that the cavitation is difficult to occur even at LOCA (loss of coolant accident) conditions. On the other hand, the suction pressure of SRPR pump is order-of-magnitude smaller than that of PWR so that the cavitation phenomena, may prevail, should LOCA occur, depending on the extent of LOCA condition. In this study, therefore, both cavitation phenomena and two-phase flow phenomena were investigated for the SRPR pump by using various analytical tools and the numerical results are presented herein.
Not Available
Risk analysis for tunneling projects
Tunnel construction is increasing world wide. Although the majority of tunnel construction projects have been completed safely, there have been several incidents that have resulted in delays, cost overruns, and sometimes ...
Sousa. Rita L
Quantum tunneling time
A simple model of a quantum clock is applied to the old and controversial problem of how long a particle takes to tunnel through a quantum barrier. The model I employ has the advantage of yielding sensible results for energy eigenstates, and does not require the use of time-dependant wave packets. Although the treatment does not forbid superluminal tunneling velocities, there is no implication of faster-than-light signaling because only the transit duration is measurable, not the absolute time of transit. A comparison is given with the weak-measurement post-selection calculations of Steinberg.
P. C. W. Davies
Giant tunneling magnetoresistance in Co{sub 2}MnSi/Al-O/Co{sub 2}MnSi magnetic tunnel junctions
Magnetic tunnel junctions (MTJs) with a stacking structure of Co{sub 2}MnSi/Al-O/Co{sub 2}MnSi were fabricated using magnetron sputtering system. Fabricated MTJ exhibited an extremely large tunneling magnetoresistance (TMR) ratio of 570% at low temperature, which is the highest TMR ratio reported to date for an amorphous Al-O tunneling barrier. The observed dependence of tunneling conductance on bias voltage clearly reveals the half-metallic energy gap of Co{sub 2}MnSi. The origins of large temperature dependence of TMR ratio were discussed on the basis of the present results.
Sakuraba, Y.; Hattori, M.; Oogane, M.; Ando, Y.; Kato, H.; Sakuma, A.; Miyazaki, T.; Kubota, H. [Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-05, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568 (Japan)
Analysis of Freeze-Thaw Embolism in Conifers. The Interaction between Cavitation Pressure
pressures may expand and cause embolism in the xylem conduits. We used the centrifuge method to evaluate. Under certain con- ditions, these bubbles nucleate cavitation, leading to a gas-filled (embolized
Pittermann, Jarmila
Cavitation Measurements on Silicone Oils by Utilization of a Pumping Effect
Characteristic types of cavitation in silicone oils of different gas content and viscosities between 3 and 760 cP have been investigated microscopically and by utilization of a cavitation?pumping effect. The transducer was a 20?kHz stepped horn with a center hole 3 mm in diameter. At hydrostatic pressures between 30 and 760 Torr and transducer amplitudes between 0 and 24 ?
Ernest G. Lierke; Heinz Wollny
Effect of cavitation on the properties of coal-tar pitch as studied by gas-liquid chromatography
The applicability of the cavitation-wave effect to coal-tar pitch processing is considered. The results of the GLC analysis of the test material before and after rotor-pulsation cavitation treatment are given. The organic matter of coal-tar pitch was found to degrade upon cavitation; as a result of this, the yields of light and medium fractions considerably increased. 5 refs., 2 figs., 4 tabs.
M.I. Baikenov; T.B. Omarbekov; S.K. Amerkhanova (and others) [Buketov State University, Karaganda (Kazakhstan)
Nonequilibrium transport in superconducting tunneling structures.
We derive the current-voltage (I-V) characteristics of far from equilibrium superconducting tunneling arrays and find that the energy relaxation ensuring the charge transfer occurs in two stages: (i) the energy exchange between charge carriers and the intermediate bosonic agent, environment, and (ii) relaxing the energy further to the (phonon) thermostat, the bath, provided the rate of the environmental modes-phonon interactions is slower than their energy exchange rate with the tunneling junction. For a single junction we find I {proportional_to} (V/R)ln({Lambda}/V), where R is the bare tunnel resistance of the junction and {Lambda} is the high energy cut-off of the electron-environment interaction. In large tunneling arrays comprised of macroscopic number of junctions, low-temperature transport is governed by the cotunneling processes losing energy to the electron-hole environment. Below some critical temperature, T*, the Coulomb interactions open a finite gap in the environment excitations spectrum blocking simultaneously Cooper pair and normal excitations currents through the array; this is the microscopic mechanism of the insulator-to-superinsulator transition.
Chtchelkatchev, N. M.; Vinokur, V. M.; Baturina, T. I. (Materials Science Division); (Moscow Inst. Physics and Technology); (Inst. Semiconductor Physics)
Antiparticle creation in tunneling
We study particle interaction with a Dirac step potential. In the standard Klein energy zone, the hypothesis of Klein pair production predicts the existence of free/oscillatory antiparticles. In this paper, we discuss the tunneling energy zone characterized by evanescent wave functions in the classically forbidden region. We ask the question of the nature, particle or antiparticle, of the densities within the classically forbidden region. The answer to this question is relevant to the correct form of the reflection coefficient.
Stefano De Leo; Pietro Rotelli
Computational design and analysis of flatback airfoil wind tunnel experiment.
Polarization Control of Electron Tunneling into Ferroelectric Surfaces
We demonstrate a highly reproducible control of local electron transport through a ferroelectric oxide via its spontaneous polarization. Electrons are injected from the tip of an atomic force microscope into a thin film of lead-zirconate titanate, Pb(Zr0.2Ti0.8)O3, in the regime of electron tunneling assisted by a high electric field (Fowler-Nordheim tunneling). The tunneling current exhibits a pronounced hysteresis with abrupt switching events that coincide, within experimental resolution, with the local switching of ferroelectric polarization. The large spontaneous polarization of the PZT film results in up to 500-fold amplification of the tunneling current upon ferroelectric switching. The magnitude of the effect is subject to electrostatic control via ferroelectric switching, suggesting possible applications in ultrahigh-density data storage and spintronics.
Maksymovych, Petro [ORNL; Jesse, Stephen [ORNL; Yu, Pu [University of California, Berkeley; Ramesh, R. [University of California, Berkeley; Baddorf, Arthur P [ORNL; Kalinin, Sergei V [ORNL
Development of a cavitating descaling technique for on-line geothermal pipe and component cleaning and scale removal. Final report
The use of cavitation for cleaning and removing geothermal scale from pipes and system components is discussed. A study of the technical feasibility of using cavitation to remove scale is described including the preliminary fold test, the GLEF in-plant field demonstration, a production line cleaning trial, and recommendations. (MHR)
Howard, S.C.; Bohli, W.H.
Nanoscale heat conduction across tunnel junctions
?2005? Nanoscale heat conduction across tunnel junctions Y.May 2005? Nanoscale heat conduction across tunnel junctionsprevailing theory of heat conduction in highly disordered
Ju, Y. Sungtaek; Hung, M T; Carey, M J; Cyrille, M C; Childress, J R
Evaluation of CAVIJET cavitating jets for deep-hole rock cutting
A feasibility study has shown that the CAVIJET cavitating fluid jet method should be capable of successfully augmenting the cutting action of mechanical bits under deep-hole conditions. Increased rock cutting rates by existing cavitating jet nozzles can be anticipated with conventional rig pressures for hole depths of at least 1200 m (4000 ft) and possibly deeper. Improved rates of penetration, based on preliminary laboratory roller bit tests, should be achieved by simply substituting CAVIJET nozzles absorbing equivalent hydraulic power for conventional roller bit nozzles.
Conn, A.F.; Johnson, V.E. Jr.; Liu, H.L.; Frederick, G.S.
Developing a Practical Wind Tunnel Test Engineering Course for Undergraduate Aerospace Engineering Students
This thesis describes the development and assessment of an undergraduate wind tunnel test engineering course utilizing the 7ft by 10ft Oran W. Nicks Low Speed Wind Tunnel (LSWT). Only 5 other universities in the United States have a wind tunnel of similar size and none have an undergraduate wind tunnel test engineering course built around it. Many universities use smaller wind tunnels for laboratory instruction, but these experiments are meant to only demonstrate basic concepts. Students go beyond conceptual learning in this wind tunnel test engineering course and conduct real-world experiments in the LSWT. This course puts knowledge into practice and further prepares students whether continuing on to graduate school or industry. Course content mainly originates from the chapters in Low Speed Wind Tunnel Testing by Barlow, Rae, and Pope. This is the most comprehensive book that addresses the specific requirements of large scale, low speed wind tunnel testing. It is not a textbook for novices. The three experiments used in the course are modeled on actual experiments that were performed at the LSWT. They are exactly what a commercial entity would want performed although the time scale is drastically reduced because of class requirements. Students complete the course with a working knowledge of the requirements of large scale, low speed wind tunnel tests because they have successfully performed real-world tests and have performed data reduction that is needed for high-quality industrial tests.
Recla, Benjamin Jeremiah
Property:Velocity(m/s) | Open Energy Information
Velocity(m/s) Velocity(m/s) Jump to: navigation, search Property Name Velocity(m/s) Property Type String Pages using the property "Velocity(m/s)" Showing 21 pages using this property. A Alden Small Flume + >0.9 + B Bucknell Hydraulic Flume + 2.7 + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + 17 + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + 25.8 + Carderock Circulating Water Channel + 5.2 + Carderock Large Cavitation Tunnel + 18 + Carderock Subsonic Wind Tunnel + 83.8 + D DeFrees Flume 1 + 2 + DeFrees Flume 2 + 2 + DeFrees Flume 3 + 2 + DeFrees Flume 4 + 2 + M MHL Free Surface Channel + 2 + MHL High Speed Cavitation + 25.9 + MHL Student Tunnel + 4.6 + P Penn Large Water Tunnel + 16.8 + Penn Small Water Tunnel + 21 + S SAFL Channel + 6.1 +
Investigation of Potential Concrete Tie Rail Seat Deterioration Mechanisms: Cavitation Erosion and Hydraulic Pressure Cracking
Investigation of Potential Concrete Tie Rail Seat Deterioration Mechanisms: Cavitation Erosion and Hydraulic Pressure Cracking 10-2411 Transportation Research Board 89th Annual Meeting Submitted: November 15-2411 1 ABSTRACT Rail seat deterioration (RSD) is the most critical problem with concrete tie performance
Barkan, Christopher P.L.
Developing a CD-CBM Anticipatory Approach for Cavitation - Defining a Model Descriptor Consistent Between Processes
A major problem with cavitation in pumps and other hydraulic devices is that there is no effective method for detecting or predicting its inception. The traditional approach is to declare the pump in cavitation when the total head pressure drops by some arbitrary value (typically 3o/0) in response to a reduction in pump inlet pressure. However, the pump is already cavitating at this point. A method is needed in which cavitation events are captured as they occur and characterized by their process dynamics. The object of this research was to identify specific features of cavitation that could be used as a model-based descriptor in a context-dependent condition-based maintenance (CD-CBM) anticipatory prognostic and health assessment model. This descriptor was based on the physics of the phenomena, capturing the salient features of the process dynamics. An important element of this concept is the development and formulation of the extended process feature vector @) or model vector. Thk model-based descriptor encodes the specific information that describes the phenomena and its dynamics and is formulated as a data structure consisting of several elements. The first is a descriptive model abstracting the phenomena. The second is the parameter list associated with the functional model. The third is a figure of merit, a single number between [0,1] representing a confidence factor that the functional model and parameter list actually describes the observed data. Using this as a basis and applying it to the cavitation problem, any given location in a flow loop will have this data structure, differing in value but not content. The extended process feature vector is formulated as follows: E`> [ , {parameter Iist}, confidence factor]. (1) For this study, the model that characterized cavitation was a chirped-exponentially decaying sinusoid. Using the parameters defined by this model, the parameter list included frequency, decay, and chirp rate. Based on this, the process feature vector has the form: @=> [, {01 = a, ~= b, ~ = c}, cf = 0.80]. (2) In this experiment a reversible catastrophe was examined. The reason for this is that the same catastrophe could be repeated to ensure the statistical significance of the data.
Allgood, G.O.; Dress, W.B.; Kercel, S.W.
Quantum tunneling, quantum computing, and high temperature superconductivity
In this dissertation, I have studied four theoretical problems in quantum tunneling, quantum computing, and high-temperature superconductivity. I have developed a generally-useful numerical tool for analyzing impurity-induced resonant-state images observed with scanning tunneling microscope (STM) in high temperature superconductors. The integrated tunneling intensities on all predominant sites have been estimated. The results can be used to test the predictions of any tight-binding model calculation. I have numerically simulated two-dimensional time-dependent tunneling of a Gaussian wave packet through a barrier, which contains charged ions. We have found that a negative ion in the barrier directly below the tunneling tip can deflect the tunneling electrons and drastically reduce the probability for them to reach the point in the target plane directly below the tunneling tip. I have studied an infinite family of sure-success quantum algorithms, which are introduced by C.-R. Hu [Phys. Rev. A {\\bf 66}, 042301 (2002)], for solving a generalized Grover search problem. Rigorous proofs are found for several conjectures made by Hu and explicit equations are obtained for finding the values of two phase parameters which make the algorithms sure success. Using self-consistent Hartree-Fock theory, I have studied an extended Hubbard model which includes quasi-long-range Coulomb interaction between the holes (characterized by parameter V). I have found that for sufficiently large V/t, doubly-charged-antiphase-island do become energetically favored localized objects in this system for moderate values of U/t, thus supporting a recent conjecture by C.-R. Hu [Int. J. Mod. Phys. B {\\bf 17}, 3284 (2003)].
Wang, Qian
Propeller design optimization for tunnel bow thrusters in the bollard pull condition
Tunnel bow thrusters are often used by large ships to provide low-speed lateral maneuverability when docking. Required to provide high thrust while essentially at a standstill, the design point for these thrusters is the ...
Wilkins, James R., IV
Initial observations of cavitation-induced erosion of liquid metal spallation target vessels at the Spallation Neutron Source
During operation of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory the mechanical properties of the AISI 316L target module are altered by high-energy neutron and proton radiation. The interior surfaces of the target vessel are also damaged by cavitation-induced erosion, which results from repetitive rapid heating of the liquid mercury by high-energy proton beam pulses. Until recently no observations of cavitation-induced erosion were possible for conditions prototypical to the SNS. Post irradiation examination (PIE) of the first and second operational SNS targets was performed to gain insight into the radiation-induced changes in mechanical properties of the 316L target material and the extent of cavitation-induced erosion to the target vessel inner surfaces. Observations of cavitation-induced erosion of the first and second operational SNS target modules are presented here, including images of the target vessel interiors and specimens removed from the target beam-entrance regions.
McClintock, David A [ORNL; Riemer, Bernie [ORNL; Ferguson, Phillip D [ORNL; Carroll, Adam J [ORNL; Dayton, Michael J [ORNL
Resonant Tunneling Device Logic Circuits
This report is a summary of the activities in the field of resonant tunneling device circuit design. The presented work has been performed by the Department of Microelectronics of the University of Dortmund (UNIDO) and the Solid-State Electronics Department of the Gerhard-Mercator University of Duisburg (GMUD) during the first year of the Microelectronics Advanced Research Initiative projects ANSWERS (Autonomous Nanoelectronic Systems with Extended Replication and Signalling) and LOCOM (Logic Circuits with Reduced Complexity based on Devices with Higher Functionality). As part of the ANSWERS work-package the principal task of UNIDO is to investigate novel logic circuit architectures for resonant tunneling devices, to perform circuit simulations, and to specify the electrical device parameters. The basic device configuration is a monolithically integrated resonant tunneling diode heterostructure field-effect transistor (RTD-HFET). This device and the demonstrator circuits are fabricated by the LOCOM partner GMUD.
Christian Pacha; Peter Gl�sek�tter; Karl Goser; Werner Prost; Uwe Auer; Franz-J. Tegude
Ivar Giaever, Tunneling, and Superconductors
Ivar Giaever, Tunneling, and Superconductors Ivar Giaever, Tunneling, and Superconductors Resources with Additional Information · Patents Ivar Giaever Courtesy of Rensselaer Polytechnic Institute 'Dr. Giaever received his engineering degree at the Norwegian Institute of Technology. After college, he emigrated to Canada, where he worked as a mechanical engineer with General Electric, and later transferred to GE's Development Center in Schenectady, N.Y. There, he shifted his interest to physics, and did graduate work at Rensselaer, receiving a Ph.D. in 1964. From 1958 to 1970, Dr. Giaever worked in the fields of thin films, tunneling, and superconductivity,'1 research that resulted in his receiving the Nobel Prize in Physics in 1973. '[I]n 1971, Dr. Giaever began studying the behavior of organic molecules at solid surfaces, and the interaction of cells with surfaces. In 1988, he became an Institute Professor of Science at Rensselaer.' 1
Large Plastic Deformation in High-Capacity Lithium-Ion Batteries Caused by Charge and Discharge
Large Plastic Deformation in High-Capacity Lithium-Ion Batteries Caused by Charge and Discharge, Massachusetts 02138 Evidence has accumulated recently that a high-capacity elec- trode of a lithium-ion battery in the particle is high, possibly leading to fracture and cavitation. I. Introduction LITHIUM-ION batteries
Suo, Zhigang
Prediction and Analysis of Rotor Tip-Clearance Flows using Large-Eddy Simulation
In order to analyze the dynamics of rotor tip-clearance flow and determine the underlying mechanism for the tip-leakage cavitation, a newly developed large-eddy simulation (LES) solver which combines an immersed-boundary method with a generalized curvilinearstructured ...
Donghyun You; Meng Wang; Parviz Moin; Rajat Mittal
Report Tunneling Cost Reduction Study prepared for Fermilab
Fermi National Accelerator Laboratories has a need to review the costs of constructing the very long tunnels which would be required for housing the equipment for the proposed Very Large Hadron Collider (VLHC) project. Current tunneling costs are high, and the identification of potential means of significantly reducing them, and thereby helping to keep overall project costs within an acceptable budget, has assumed great importance. Fermilab has contracted with The Robbins Company to provide an up-to-date appraisal of tunneling technology, and to review the potential for substantially improving currently the state-of-practice performance and construction costs in particular. The Robbins Company was chosen for this task because of its long and successful experience in hard rock mechanical tunnel boring. In the past 40 years, Robbins has manufactured over 250 tunneling machines, the vast majority for hard rock applications. In addition to also supplying back-up equipment, Robbins has recently established a division dedicated to the manufacture of continuous conveying equipment for the efficient support of tunneling operations. The study extends beyond the tunnel boring machine (TBM) itself, and into the critical area of the logistics of the support of the machine as it advances, including manpower. It is restricted to proven methods using conventional technology, and its potential for incremental but meaningful improvement, rather than examining exotic and undeveloped means of rock excavation that have been proposed from time to time by the technical community. This is the first phase of what is expected to be a number of studies in increasing depth of technical detail, and as such has been restricted to the issues connected with the initial 34 kilometer circumference booster tunnel, and not the proposed 500 kilometer circumference tunnel housing the VLHC itself. The booster tunnel is entirely sited within low to medium strength limestone and dolomite formations, typical of the Chicago area. The rock is generally competent with widely spaced jointing, and slowdown of the operation for the installation of rock support is expected to be minimal. The tunneling system will have to be equipped with the necessary equipment for an efficient response to poor rock conditions however. Because the ground conditions are expected to be very favorable, a state-of-the-art TBM should have no difficulty in excavating at a high penetration rate of 10 meters per hour or more in rock of the average of the range of strengths stated to exist. Disc cutter changes will be few as the rock has very low abrasivity. However, experience has shown that overall tunneling rates are a relatively low percentage of the machine's penetration rate capability. Therefore the main focus of improvement is guaranteeing that the support systems, including mucking and advance of the utilities do not impede the operation. Improved mechanization of the support systems, along with automation where practicable to reduce manpower, is seen as the best means of raising the overall speed of the operation, and reducing its cost. The first phase of the study is mainly involved with establishing the baseline for current performance, and in identifying areas of improvement. It contains information on existing machine design concepts and provides data on many aspects of the mechanical tunneling process, including costs and labor requirements. While it contains suggestions for technical improvements of the various system, the time limitations of this phase have not permitted any detailed concept development. This should be a major part of the next phase.
Evaluation of Cavitation-Erosion Resistance of 316LN Stainless Steel in Mercury Containing Metallic Solutes
Room temperature cavitation tests of vacuum annealed type 316LN stainless steel were performed in pure Hg and in Hg with various amounts of metallic solute to evaluate potential mitigation of erosion/wastage. Tests were performed using an ultrasonic vibratory horn with specimens attached at the tip. All of the solutes examined, which included 5 wt% In, 10 wt% In, 4.4 wt% Cd, 2 wt% Ga, and a mixture that included 1 wt% each of Pb, Sn, and Zn, were found to increase cavitation-erosion as measured by increased weight loss and/or surface profile development compared to exposures for the same conditions in pure Hg. Qualitatively, each solute appeared to increase the post-test wetting tenacity of the Hg solutions and render the Hg mixture susceptible to manipulation of droplet shape.
Pawel, Steven J [ORNL; Mansur, Louis K [ORNL
Cavitation-erosion resistance of 316LN stainless steel in mercury containing metallic solutes
Room temperature cavitation tests of vacuum annealed type 316LN stainless steel were performed in pure mercury and in mercury with various amounts of metallic solute to evaluate potential mitigation of erosion/wastage. Tests were performed using an ultrasonic vibratory horn with specimens attached at the tip. All of the solutes examined, which included 5 wt% In, 10 wt% In, 4.4 wt% Cd, 2 wt% Ga, and a mixture that included 1 wt% each of Pb, Sn, and Zn, were found to increase cavitation-erosion as measured by increased weight loss and/or surface profile development compared to exposures for the same conditions in pure mercury. Qualitatively, each solute appeared to increase the tenacity of the post-test wetting of the Hg solutions and render the Hg mixture susceptible to manipulation of droplet shape. Published by Elsevier B.V.
Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel
The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.
Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)
Resonance tunneling spectroscopy of heteropoly compounds
The electron tunneling spectra of phosphomolybdic and phosphomolybdovanadic acids have been measured using a scanning tunneling microscope. A new mechanism of negative differential resistance (NDR) formation in tunneling nanocontacts is established, which is general for all systems featuring the Wannier-Stark localization effect. A two-center inelastic resonance tunneling model is constructed, which allows the values of both electron and vibrational energy parameters to be determined from the measured spectra.
Dalidchik, F. I., E-mail: email@example.com; Budanov, B. A.; Kolchenko, N. N.; Balashov, E. M.; Kovalevskii, S. A. [Russian Academy of Sciences, Semenov Institute of Chemical Physics (Russian Federation)
Tunable Compression of Wind Tunnel Data
Tunable Compression of Wind Tunnel Data. Summary: Measurements of pressures exerted by wind on buildings, as are ...
Simulating scanning tunneling microscope measurements
One of the largest problems in scanning tunneling microscopy design is noise control. It is the burden of the designer to determine if money should be used to build a floating room for vibration isolation or for top-of-the-line ...
Venkatachalam, Vivek
Macroscopic quantum tunneling with decoherence
The tunneling probability for a system modelling macroscopic quantum tunneling is computed. We consider an open quantum system with one degree of freedom consisting of a particle trapped in a cubic potential interacting with an environment characterized by a dissipative and a diffusion parameter. A representation based on the energy eigenfunctions of the isolated system, i. e. the system uncoupled to the environment, is used to write the dynamical master equation for the reduced Wigner function of the open quantum system. This equation becomes very simple in that representation. The use of the WKB approximation for the eigenfunctions suggests an approximation which allows an analytic computation of the tunneling rate, in this real time formalism, when the system is initially trapped in the false ground state. We find that the decoherence produced by the environment suppresses tunneling in agreement with results in other macroscopic quantum systems with different potentials. We confront our analytical predictions with an experiment where the escape rate from the zero voltage state was measured for a current-biased Josephson junction shunted with a resistor.
Esteban Calzetta; Enric Verdaguer
Photon Aided and Inhibited Tunneling of Photons
In the light of the interest in the transport of single photons in arrays of waveguides, fiber couplers, photonic crystals, etc., we consider the quantum mechanical process of the tunneling of photons through evanescently or otherwise coupled structures. We specifically examine the issue of tunneling between two structures when one structure already contains few photons. We demonstrate the possibility of both photon aided and inhibited tunneling of photons. The Bosonic nature of photons enhances the tunneling probability. We also show how the multiphoton tunneling probability can be either enhanced or inhibited due to the presence of photons. We find similar results for the higher order tunneling. Finally, we show that the presence of a squeezed field changes the nature of tunneling considerably.
liu, xuele
Assessment of Cavitation-Erosion Resistance of 316LN Stainless Steel Following a Nitro-Carburizing Surface Treatment
A nitro-carburizing surface treatment known domestically as the Melonite process was applied to type 316LN stainless steel test pieces and exposed to sonication conditions in mercury using a vibratory horn technique. Cavitation-erosion damage was evaluated for extended exposures and compared to other surface treatments on the same substrate alloy. The results indicate that the Melonite process substantially retards weight loss and crater development for extended periods, but gradually is eroded/destroyed leading to exposure of the substrate and cavitation-erosion behavior similar to untreated specimens. Compared with other surface treatments, cavitation-erosion results indicate that specimens treated with Melonite perform similarly to specimens treated with a simple nitriding process. Neither the simple nitriding nor the Melonite treatment is quite as effective as a previously evaluated low temperature carburizing treatment, the latter being about a factor of three better than Melonite in terms of weight loss during sonication in mercury.
Pawel, Steven J [ORNL
Recrossing and Heavy-atom Tunneling in Common Organic Reactions
Non-statistical recrossing in ketene cycloadditions with alkenes, heavy-atom tunneling and the mechanism of the decarboxylation of Mandelylthiamin is investigated in this dissertation. A combination of experimental kinetic isotope effects and theoretical models and kinetic isotope effects is utilized for this endeavor. This dissertation also describes how the use of quasiclassical dynamic trajectories, microcanonical RRKM calculations, and canonical variational transition state theory in combination with small-curvature tunneling approximations is utilized to help advance our research methodology to better understand mechanism. In the cycloaddition of dichloroketene with cis-2-butene, significant amounts of recrossing is observed using quasiclassical dynamic trajectories. An unusual inverse 13C intramolecular KIE lead us to investigate the role that heavy atoms play in non-statistical recrossing. More importantly, this discovery has uncovered a new phenomena of entropic intermediates that not only applies to ketene cycloadditions, but can also be applicable to other "concerted" reactions such as Diels-Alder reactions. The ring-opening of cyclopropylcarbinyl radical has revealed that heavy-atom tunneling plays a major role. The intramolecular 13C kinetic isotope effects for the ring-opening of cyclopropylcarbinyl radical were unprecedentedly large and in combination with theoretical predictions and multidimensional tunneling corrections, the role of tunneling in this reaction can be better understood. The mechanism decarboxylation of mandelylthiamin has been extensively studied in the literature. However, until the use of theoretically predicted KIEs and theoretical binding motifs the rate-limiting step of this reaction has been hotly debated. In this dissertation, a discussion of how the theoretical KIEs indicate the initial C-C bond as the rate-limiting step and chelating binding motifs of pyridinium and mandelylthiamin to explain the observed catalysis is given.
James, Ollie
Chaos regularization of quantum tunneling rates
Quantum tunneling rates through a barrier separating two-dimensional, symmetric, double-well potentials are shown to depend on the classical dynamics of the billiard trajectories in each well and, hence, on the shape of the wells. For shapes that lead to regular (integrable) classical dynamics the tunneling rates fluctuate greatly with eigenenergies of the states sometimes by over two orders of magnitude. Contrarily, shapes that lead to completely chaotic trajectories lead to tunneling rates whose fluctuations are greatly reduced, a phenomenon we call regularization of tunneling rates. We show that a random-plane-wave theory of tunneling accounts for the mean tunneling rates and the small fluctuation variances for the chaotic systems.
Pecora, Louis M.; Wu Dongho [Materials Physics and Sensors, US Naval Research Laboratory, Washington, DC 20375 (United States); Lee, Hoshik [Department of Physics, College of William and Mary, Williamsburg, Virginia 23187 (United States); Antonsen, Thomas; Lee, Ming-Jer; Ott, Edward [Physics and Electrical Engineering Departments, University of Maryland, College Park, Maryland 20742 (United States)
Space Institute Tunnel | Open Energy Information
Tunnel Tunnel Jump to: navigation, search Basic Specifications Facility Name Space Institute Tunnel Overseeing Organization University of Tennessee Hydrodynamic Testing Facility Type Tunnel Length(m) 1.5 Beam(m) 0.4 Depth(m) 0.5 Cost(per day) ~$1000 (Contact POC for estimate) Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 0.9 Recirculating Yes Wind Capabilities Wind Capabilities None Control and Data Acquisition Description Computer with National Instruments SCXI DAS Chassis Number of channels 32 Bandwidth(kHz) Varies with number of channels and specific module/board Cameras Yes Available Sensors Flow, Strain, Turbulence Data Generation Capability
Feasibility study of tuned-resonator, pulsating cavitating water jet for deep-hole drilling
This study presents the advantages of pulsing a submerged jet to increase its erosion capability (particularly as caused by cavitation) in augmenting deep-hole drill bits. Various methods of accomplishing the pulsation are presented and discussed. The most attractive systems uncovered are acoustic oscillators which passively accomplish pulsations in the flow at frequencies corresponding to a Strouhal number in the range of 0.2 to 1.0. Such passive oscillators are assessed to be feasible candidates for development into practical deep hole drill bit systems and a long range plan for this research and development is presented and discussed.
Johnson, V.E. Jr.; Lindenmuth, W.T.; Conn, A.F.; Frederick, G.S.
Wind tunnel model testing of offshore platforms.
?? The purpose of this thesis is to highlight some of the areas of interest when it comes to wind tunnel experimenting of offshore platforms� (more)
Abrahamsen, Ida Sinnes
Optical modulation in a resonant tunneling relaxation oscillator
We report high speed optical modulation in a resonant tunneling relaxation oscillator consisting of a resonant tunneling diode (RTD) integrated with a unipolar optical waveguide and incorporated in a package with a coplanar waveguide transmission line. When appropriately biased, the RTD can provide wide-bandwidth electrical gain. For wavelengths near the material band-edge, small changes of the applied voltage give rise to large, high-speed electro-absorption modulation of the light. We have observed optical modulation at frequencies up to 14 GHz, associated with sub harmonic injection locking of the RTD oscillation at the fundamental mode of the coplanar transmission line, as well as generation of 33 ps optical pulses due to relaxation oscillation.
Figueiredo, J M L; Boyd, A R; Ironside, C N
Recommendations for Controlling Cavitation, Flashing, Liquid Droplet Impingement, and Solid Particle Erosion in Nuclear Power Plant Piping Systems
This report describes the most common forms of erosion encountered in nuclear power plant piping systems�cavitation, flashing, liquid droplet impingement, and solid particle erosion�and provides utility engineers with information on how to deal with these forms of damage.
Carderock Subsonic Wind Tunnel | Open Energy Information
Subsonic Wind Tunnel Subsonic Wind Tunnel Jump to: navigation, search Basic Specifications Facility Name Carderock Subsonic Wind Tunnel Overseeing Organization United States Naval Surface Warfare Center Hydrodynamic Testing Facility Type Tunnel Length(m) 4.3 Beam(m) 3.0 Depth(m) 2.4 Water Type Freshwater Cost(per day) Contact POC Special Physical Features The Subsonic Wind Tunnel is a continuous flow, closed-circuit facility with a closed jet test section. Test models may be supported by strut mounts using the external balance or by sting mounts using any of a wide selection of internal strain gauge balances. Adjustable surface planes are available for simulation of ground or water surfaces. Full-width floor and ceiling turntables provide additional flexibility in model mounting and manipulation.
MHL Student Tunnel | Open Energy Information
Student Tunnel Student Tunnel Jump to: navigation, search Basic Specifications Facility Name MHL Student Tunnel Overseeing Organization University of Michigan Hydrodynamics Hydrodynamic Testing Facility Type Channel Length(m) 1.4 Beam(m) 0.4 Depth(m) 0.3 Cost(per day) $2000(+ Labor/Materials) Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Velocity(m/s) 4.6 Recirculating No Wind Capabilities Wind Capabilities None Control and Data Acquisition Description Custom Data Acquisition System using National Instruments hardware; system compatible with Planing Hull and Floating Beam Dynamometers Number of channels 16 Bandwidth(kHz) 20 Cameras Yes Description of Camera Types Wide variety of analog & digital surface cameras; high speed above and underwater cameras
A 233 km tunnel for lepton and hadron colliders
A decade ago, a cost analysis was conducted to bore a 233 km circumference Very Large Hadron Collider (VLHC) tunnel passing through Fermilab. Here we outline implementations of e{sup +}e{sup -}, pp-bar , and {mu}{sup +}{mu}{sup -} collider rings in this tunnel using recent technological innovations. The 240 and 500 GeV e{sup +}e{sup -} colliders employ Crab Waist Crossings, ultra low emittance damped bunches, short vertical IP focal lengths, superconducting RF, and low coercivity, grain oriented silicon steel/concrete dipoles. Some details are also provided for a high luminosity 240 GeV e{sup +}e{sup -} collider and 1.75 TeV muon accelerator in a Fermilab site filler tunnel. The 40 TeV pp-bar collider uses the high intensity Fermilab p-bar source, exploits high cross sections for pp-bar production of high mass states, and uses 2 Tesla ultra low carbon steel/YBCO superconducting magnets run with liquid neon. The 35 TeV muon ring ramps the 2 Tesla superconducting magnets at 9 Hz every 0.4 seconds, uses 250 GV of superconducting RF to accelerate muons from 1.75 to 17.5 TeV in 63 orbits with 71% survival, and mitigates neutrino radiation with phase shifting, roller coaster motion in a FODO lattice.
Summers, D. J.; Cremaldi, L. M.; Datta, A.; Duraisamy, M.; Luo, T.; Lyons, G. T. [Dept. of Physics and Astronomy, University of Mississippi-Oxford, University, MS 38677 (United States)
Topological tunneling with Dynamical overlap fermions
Tunneling between different topological sectors with dynamical chiral fermions is difficult because of a poor mass scaling of the pseudo-fermion estimate of the determinant. For small fermion masses it is virtually impossible using standard methods. However, by projecting out the small Wilson eigenvectors from the overlap operator, and treating the correction determinant exactly, we can significantly increase the rate of topological sector tunneling and reduce substantially the auto-correlation time. We present and compare a number of different approaches, and advocate a method which allows topological tunneling even at low mass with little addition to the computational cost.
Nigel Cundy; Stefan Krieg; Thomas Lippert; Andreas Schaefer
Methods for the fabrication of thermally stable magnetic tunnel junctions
DOE Patents (OSTI)
Magnetic tunnel junctions and method for making the magnetic tunnel junctions are provided. The magnetic tunnel junctions are characterized by a tunnel barrier oxide layer sandwiched between two ferromagnetic layers. The methods used to fabricate the magnetic tunnel junctions are capable of completely and selectively oxidizing a tunnel junction precursor material using an oxidizing gas containing a mixture of gases to provide a tunnel junction oxide without oxidizing the adjacent ferromagnetic materials. In some embodiments the gas mixture is a mixture of CO and CO.sub.2 or a mixture of H.sub.2 and H.sub.2O.
Chang, Y. Austin (Middleton, WI); Yang, Jianhua J. (Madison, WI); Ladwig, Peter F. (Hutchinson, MN)
CAVITATION DAMAGE MEASUREMENTS IN MERCURY BY RADIOTRACER ANALYSIS. Technical Report No. 10
The development of a method of continuous measurement of the wear of metal specimens submitted to a constant cavitation field by using radiotracer techniques was attempted. Samples of type 302 stainless steel and type 1010 carbon steel were irradiated in a nuclear reactor and then placed in a cavitating venturi in a closed-loop mercury facility. It was discovered that due to the arrangement of the centrifugal pump, the radioactive particles of steel separate at once and tend to be trapped on the liquid surface of the pump sump. By dismantling this sump, about 6% of the measured weight loss of the carbon steel specimens was recovered. This radioactive material was collected and filtered, which allowed a classification by size with the following results: 68.95% of the material was retained on a 53 micron filter, 30.75% was retained on a 10 micron filter, and 0.307% was retained on a 2 micron filter. These results were obtained by comparison of the activity of the debris with the activity of a standard sample prepared from the original irradiated specimen. Differential curves obtained for the different size debris indicate that the constituents do not vary with particle size. On the assumption that the particles are spheres, it was found that the size distribution of the debris recovered was as follows: 6000 particles with a diameter of 53 microns, 14,750 with an average diameter of 30 microns, and 18,400 with an average diameter of 6 microns. Very few particles exceed a diameter of 80 microns (3.15 mils) and very few have a dimension of less than 6 microns (.236 mils). (auth)
Smith, W.; Nieto, J.M.; Hammitt, F.G.
Soliton in a Well. Dynamics and Tunneling
We derive the leading order radiation through tunneling of an oscillating soliton in a well. We use the hydrodynamic formulation with a rigorous control of the errors for finite times.
V. Fleurov; A. Soffer
How big around is the tunnel at...
actually two linear accelerators linked by arcs at the ends. There is also a web-based tour of the accelerator that you might find entertaining. What we do in the tunnel could...
Dissociative recombination: Crossing and tunneling modes
This report discusses the process of dissociative reconsiderations. The particular topics covered are: Upper Limit to Rate Coefficient; Tunneling Dissociative Recombinations; and Signature of Polyatomic Ion Dissociative Recombination. 210 refs., 151 figs., 7 tabs.
Bates, D.R. [Queen`s Univ. of Belfast (United Kingdom)
Semiconductor tunnel junction with enhancement layer
The incorporation of a pseudomorphic GaAsSb layer in a runnel diode structure affords a new degree of freedom in designing runnel junctions for p-n junction device interconnects. Previously only doping levels could be varied to control the tunneling properties. This invention uses the valence band alignment band of the GaAsSb with respect to the surrounding materials to greatly relax the doping requirements for tunneling.
Klem, John F. (Sandia Park, NM); Zolper, John C. (Albuquerque, NM)
Smart bridges, smart tunnels: Transforming wireless sensor networks from research prototypes into robust engineering infrastructure
We instrumented large civil engineering infrastructure items, such as bridges and tunnels, with sensors that monitor their operational performance and deterioration. In so doing we discovered that commercial offerings of wireless sensor networks (WSNs) ... Keywords: Civil engineering, Deployment, Radio propagation, Realworld experience, Security, Wireless sensor networks
Frank Stajano; Neil Hoult; Ian Wassell; Peter Bennett; Campbell Middleton; Kenichi Soga
Hoosac tunnel geothermal heat source. Final report
The Hoosac Rail Tunnel has been analyzed as a central element in a district heating system for the City of North Adams. The tunnel has been viewed as a collector of the earth's geothermal heat and a seasonal heat storage facility with heat piped to the tunnel in summer from existing facilities at a distance. Heated fluid would be transported in winter from the tunnel to users who would boost the temperature with individual heat pumps. It was concluded the tunnel is a poor source of geothermal heat. The maximum extractable energy is only 2200 million BTU (20000 gallons of oil) at 58/sup 0/F. The tunnel is a poor heat storage facility. The rock conductivity is so high that 75% of the heat injected would escape into the mountain before it could be recaptured for use. A low temperature system, with individual heat pumps for temperature boost could be economically attractive if a low cost fuel (byproduct, solid waste, cogeneration) or a cost effective seasonal heat storage were available.
Comparison of Cavitation-Erosion Resistance of Carburized and Carburized-Plus-Nitrided 316LN Stainless Steel in Mercury
Annealed type 316LN stainless steel in the (1) carburized and the (2) carburized plus nitrided conditions was evaluated for cavitation-erosion resistance in ambient temperature mercury using a vibratory horn method. The results indicated that, relative to the specimens receiving only the carburizing treatment, the specimens that received both surface treatments exhibited substantially greater weight loss, general thinning, and profile development as a function of sonication time - with all observed degradation limited to the nitrided layer. Further, the nitride layer was observed to be susceptible to extensive cracking (occasionally leading to spallation), but the cracking was never observed to penetrate into the carburized layer. These screening test results suggest there is no improvement in cavitation-erosion resistance associated with augmentation of the carburizing treatment with plasma nitriding.
Assessment of Cavitation-Erosion Resistance of Potential Pump Impeller Materials for Mercury Service at the Spallation Neutron Source
Using a standard vibratory horn apparatus, the relative cavitation-erosion resistance of a number of cast alloys in mercury was evaluated to facilitate material selection decisions for Hg pumps. The performance of nine different alloys - in the as-cast condition as well as following a case-hardening treatment intended to increase surface hardness - was compared in terms of weight loss and surface profile development as a function of sonication time in Hg at ambient temperature. The results indicated that among several potentially suitable alloys, CD3MWCuN perhaps exhibited the best overall resistance to cavitation in both the as-cast and surface treated conditions while the cast irons examined were found unsuitable for service of this type. However, other factors, including cost, availability, and vendor schedules may influence a material selection among the suitable alloys for Hg pumps.
Analytical and experimental study of the acoustics and the flow field characteristics of cavitating self-resonating water jets
Waterjet nozzles (STRATOJETS) have been developed which achieve passive structuring of cavitating submerged jets into discrete ring vortices, and which possess cavitation incipient numbers six times higher than obtained with conventional cavitating jet nozzles. In this study we developed analytical and numerical techniques and conducted experimental work to gain an understanding of the basic phenomena involved. The achievements are: (1) a thorough analysis of the acoustic dynamics of the feed pipe to the nozzle; (2) a theory for bubble ring growth and collapse; (3) a numerical model for jet simulation; (4) an experimental observation and analysis of candidate second-generation low-sigma STRATOJETS. From this study we can conclude that intensification of bubble ring collapse and design of highly resonant feed tubes can lead to improved drilling rates. The models here described are excellent tools to analyze the various parameters needed for STRATOJET optimizations. Further analysis is needed to introduce such important factors as viscosity, nozzle-jet interaction, and ring-target interaction, and to develop the jet simulation model to describe the important fine details of the flow field at the nozzle exit.
Chahine, G.L.; Genoux, P.F.; Johnson, V.E. Jr.; Frederick, G.S.
Property:Recirculating | Open Energy Information
Recirculating Recirculating Jump to: navigation, search Property Name Recirculating Property Type String Pages using the property "Recirculating" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + No + 10-ft Wave Flume Facility + No + 5 5-ft Wave Flume Facility + No + 6 6-ft Wave Flume Facility + No + A Alden Large Flume + Yes + Alden Small Flume + No + B Bucknell Hydraulic Flume + Yes + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + Yes + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + Yes + Carderock Large Cavitation Tunnel + Yes + Carderock Subsonic Wind Tunnel + Yes + Conte Large Flume + No + Conte Small Flume + No + D DeFrees Flume 1 + No + DeFrees Flume 2 + No + DeFrees Flume 3 + No +
Method of fabricating a solar cell with a tunnel dielectric layer
Methods of fabricating solar cells with tunnel dielectric layers are described. Solar cells with tunnel dielectric layers are also described.
Dennis, Tim; Harrington, Scott; Manning, Jane; Smith, David; Waldhauer, Ann
Understanding crack versus cavitation in pressure-sensitive adhesives: the role of kinetics
We perform traction experiments on viscous liquids highly confined between parallel plates, a geometry known as the probe-tack test in the adhesion community. Direct observation during the experiment coupled to force measurement shows the existence of several mechanisms for releasing the stress. Bubble nucleation and instantaneous growth had been observed in a previous work. Upon increasing further the traction velocity or the viscosity, the bubble growth is progressively delayed. At high velocities, cracks at the interface between the plate and the liquid appear before the bubbles have grown to their full size. Bubbles and cracks are thus observed concomitantly. At even higher velocities, cracks develop fully so early that the bubbles are not even visible. We present a theoretical model that describes these regimes, using a Maxwell fluid as a model for the actual fluid, a highly viscous silicon oil. We present the resulting phase diagramme for the different force peak regimes. The predictions are compatible with the data. Our results show that in addition to cavitation, interfacial cracks are encountered in a probe-tack traction test with viscoelastic, \\emph{liquid} materials and not solely with viscoelastic solids like adhesives.
J�r�mie Teisseire; F. Nallet; P. Fabre; Cyprien Gay
Damage assessment from proton beam induced cavitation experiments on mercury spallation targets done at the LANSCE WNR facility has been completed. The experiments investigated two key questions for the Spallation Neutron Source target, namely, how damage is affected by flow velocity in the SNS coolant channel geometry, and how damage scales with proton beam intensity at a given constant charge per pulse. With regard to the former question, prior in-beam experiments indicated that the coolant channel geometry with stagnant mercury was especially vulnerable to damage which might warrant a design change. Yet other results indicated a reduction in damage with the introduction of flow. Using more prototypic to the SNS, the 2008 experiment damage results show the channel is less vulnerable than the bulk mercury side of the vessel wall. They also show no benefit from increasing channel flow velocity beyond nominal SNS speeds. The second question probed a consensus belief that damage scales with beam intensity (protons per unit area) by a power law dependence with exponent of around 4. Results from a 2005 experiment did not support this power law dependence but some observations were inconsistent and unexplained. These latest results show weaker damage dependence.
Riemer, Bernie [ORNL; Abdou, Ashraf A [ORNL; Felde, David K [ORNL; Sangrey, Robert L [ORNL; Wendel, Mark W [ORNL
Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers
This invention relates to magnetic tunnel junctions and methods for making the magnetic tunnel junctions. The magnetic tunnel junctions include a tunnel barrier oxide layer sandwiched between two ferromagnetic layers both of which are epitaxial or textured with respect to the underlying substrate upon which the magnetic tunnel junctions are grown. The magnetic tunnel junctions provide improved magnetic properties, sharper interfaces and few defects.
Chang, Y. Austin (Middleton, WI); Yang, Jianhua Joshua (Madison, WI)
A Note on Real Tunneling Geometries
In the Hartle-Hawking ``no boundary'' approach to quantum cosmology, a real tunneling geometry is a configuration that represents a transition from a compact Riemannian spacetime to a Lorentzian universe. I complete an earlier proof that in three spacetime dimensions, such a transition is ``probable,'' in the sense that the required Riemannian geometry yields a genuine maximum of the semiclassical wave function.
S. Carlip
Charged fermions tunneling from regular black holes
We study Hawking radiation of charged fermions as a tunneling process from charged regular black holes, i.e., the Bardeen and ABGB black holes. For this purpose, we apply the semiclassical WKB approximation to the general covariant Dirac equation for charged particles and evaluate the tunneling probabilities. We recover the Hawking temperature corresponding to these charged regular black holes. Further, we consider the back-reaction effects of the emitted spin particles from black holes and calculate their corresponding quantum corrections to the radiation spectrum. We find that this radiation spectrum is not purely thermal due to the energy and charge conservation but has some corrections. In the absence of charge, e = 0, our results are consistent with those already present in the literature.
Sharif, M., E-mail: firstname.lastname@example.com; Javed, W., E-mail: email@example.com [University of the Punjab, Department of Mathematics (Pakistan)
Dynamical overlap fermions with increased topological tunnelling
We present two improvements to our previous dynamical overlap HMC algorithm. We introduce a new method of differentiating the eigenvectors of the Kernel operator, which removes an instability in the fermionic force. Secondly, by simulating part of the fermion determinant exactly, without pseudo-fermions, we are able to increase the rate of topological tunnelling by a factor of more than ten, reducing the auto-correlation.
N. Cundy; S. Krieg; T. Lippert; A Schaefer
PUREX storage tunnels waste analysis plan
Washington Administrative Code 173-303-300 requires that a facility develop and follow a written waste analysis plan which describes the procedures that will be followed to ensure that its dangerous waste is managed properly. This document covers the activities at the PUREX Storage Tunnels used to characterize and designate waste that is generated within the PUREX Plant, as well as waste received from other on-site sources.
Haas, C.R., Westinghouse Hanford
The Quantum Hydrodynamic Description of Tunneling
The quantum hydrodynamic approach is based on the de Broglie-Bohm formulation of quantum mechanics. The resulting fluid-like equations of motion describe the flow of probability and an accurate solution to these equations is equivalent to solving the time-dependent Schroedinger equation. Furthermore, the hydrodynamic approach provides new insight into the mechanisms as well as an alternative computational approach for treating tunneling phenomena. New concepts include well-defined 'quantum trajectories', 'quantum potential', and 'quantum force' all of which have classical analogues. The quantum potential and its associated force give rise to all quantum mechanical effects such as zero point energy, tunneling, and interference. A new numerical approach called the Iterative Finite Difference Method (IFDM) will be discussed. The IFDM is used to solve the set of non-linear coupled hydrodynamic equations. It is 2nd-order accurate in both space and time and exhibits exponential convergence with respect to the iteration count. The stability and computational efficiency of the IFDM is significantly improved by using a 'smart' Eulerian grid which has the same computational advantages as a Lagrangian or Arbitrary Lagrangian Eulerian (ALE) grid. The IFDM is also capable of treating anharmonic potentials. Example calculations using the IFDM will be presented which include: a one-dimensional Gaussian wave packet tunneling through an Eckart barrier, a one-dimensional bound-state Morse oscillator, and a two-dimensional (2D) model collinear reaction using an anharmonic potential energy surface. Approximate treatments of the quantum hydrodynamic equations will also be discussed which could allow scaling of the calculations to hundreds of degrees of freedom which is important for treating tunneling phenomena in condensed phase systems.
Kendrick, Brian K. [Los Alamos National Laboratory
Resonant tunneling diodes: Models and properties
The resonant tunneling diode (RTD) has been widely studied because of its importance in the field of nanoelectronic science and technology and its potential applications in very high speed/functionality devices and circuits. Even though much progress has been made in this regard, additional work is needed to realize the full potential of RTD�s. As research on RTD�s continues, we will try in this tutorial review to provide the reader with an overall and succinct picture of where we stand in this exciting field of research and to address the following questions: What makes RTD�s so attractive? To what extent can RTD�s be modeled for design purposes? What are the required and achievable device properties in terms of digital logic applications? To address these issues, we review the device operational principles, various modeling approaches, and major device properties. Comparisons among the various RTD physical models and major features of RTD�s, resonant interband tunneling diodes, and Esaki tunnel diodes are presented. The tutorial and analysis provided in this paper may help the reader in becoming familiar with current research efforts, as well as to examine the important aspects in further RTD developments and their circuit applications.
Jian Ping Sun; George I. Haddad; Pinaki Mazumder; Joel N. Schulman
Oxygen-Induced Symmetrization and Structural Coherency in Fe/MgO/Fe(001) Magnetic Tunnel Junctions
We present x-ray diffraction experiments and multiple-scattering calculations on the structure and transport properties of a Fe/MgO/Fe(001) magnetic tunnel junction (MTJ). Coherent growth of the top Fe electrode on the MgO spacer is observed only for Fe deposition in ambient oxygen atmosphere leading to a coherent and symmetric MTJ structure characterized by FeO layers at both Fe/MgO interfaces. This goes in parallel with calculations indicating large positive tunnel magnetoresistance (TMR) values in such symmetric junctions. The results have important implications for achieving giant TMR values.
Tusche, C.; Meyerheim, H.L.; Ernst, A.; Henk, J.; Bruno, P.; Kirschner, J. [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany); Jedrecy, N. [Institut des NanoSciences de Paris, Universites Paris 6 et 7, et CNRS-UMR 7588, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Renaud, G. [CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble (France)
Using Daylight to Light the Access Zone of Road Tunnels
Using Daylight to Light the Access Zone of Road Tunnels Using Daylight to Light the Access Zone of Road Tunnels Speaker(s): Eliyahu Ne'eman Date: March 4, 2003 - 12:00pm Location: Bldg. 90 Lighting guides for roadway tunnels specify relatively high luminances for the "access zone" into the tunnel. They are needed to allow the eyes of the driver sufficient time to adapt during the short period of the transition from the outdoor natural daylight levels to the fairly low luminances along the main length of the tunnel. Usually, the necessary high luminances are provided by rows of costly luminaries which consume a lot of electricity during peak use periods and need a good deal of maintenance. To save some electric power, controls are used to dim the lighting on cloudy hours. Daylight has been used for the access zone in several tunnels around the
Geologic mapping of tunnels using photogrammetry: Camera and target positioning
A photogrammetric method has been developed by the US Geological Survey and the US Bureau of Reclamation for the use in geologic mapping of tunnels (drifts). The method requires photographing the tunnel walls and roof with a calibrated small-format camera to obtain stereo pairs of photos which are then oriented in an analytical stereo plotter for measurement of geologic features. The method was tested in G-tunnel at Rainier Mesa on the Nevada Test Site. Calculations necessary to determine camera and target positions and problems encountered during testing were used to develop a set of generic formulas that can be applied to any tunnel. 7 figs.
Coe, J.A. [Geological Survey, Denver, CO (United States); Dueholm, K.S. [Danmarks Tekniske Hoejskole, Lyngby (Denmark). Inst. of Surveying and Photogrammetry
Calculation of tunneling rates across a barrier with continuous potential
Here, approximate, but accurate expressions for calculation of wavefunctions and tunneling rates are obtained using the method of uniform asymptotic expansion.
Sina Khorasani
Conte Large Flume | Open Energy Information
Conte Large Flume Conte Large Flume Overseeing Organization United States Geological Survey, LSC Hydrodynamic Testing Facility Type Flume Length(m) 38.1 Beam(m) 6.1 Depth(m) 5.2 Cost(per day) Contact POC Towing Capabilities Towing Capabilities None Wavemaking Capabilities Wavemaking Capabilities None Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Recirculating No Wind Capabilities Wind Capabilities None Control and Data Acquisition Description National Instruments LabView and other data acquisition systems Number of channels 12 Bandwidth(kHz) 44 Cameras Yes Number of Color Cameras 5 Description of Camera Types Conventional underwater video, 4; high speed (1000 fps), 1 Available Sensors Displacement, Flow, Pressure Range(psi), Thermal, Turbulence, Velocity Data Generation Capability
First-principles study of the critical thickness in asymmetric ferroelectric tunnel junctions
The absent critical thickness of fully relaxed asymmetric ferroelectric tunnel junctions is investigated by first-principles calculations. The results show that PbTiO{sub 3} thin film between Pt and SrRuO{sub 3} electrodes can still retain a significant and stable polarization down to thicknesses as small as 0.8 nm, quite unlike the case of symmetric ferroelectric tunnel junctions. We trace this surprising result to the generation of a large electric field by the charge transfer between the electrodes caused by their different electronic environments, which acts against the depolarization field and enhances the ferroelectricity, leading to the reduction, or even complete elimination, for the critical thickness.
Cai Mengqiu [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); School of Physics and Microelectronics Science, Hunan University, Changsha 410082, Hunan (China); State Key Laboratory of Optoelectronic Materials and Technologies, Zhongshan University, Guangzhou 510275, Guangdong (China); Du Yong; Huang Boyun [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)
Competition between cotunneling, Kondo effect, and direct tunneling in discontinuous high-anisotropy magnetic tunnel junctions
The transition between Kondo and Coulomb blockade effects in discontinuous double magnetic tunnel junctions is explored as a function of the size of the CoPt magnetic clusters embedded between AlO{sub x} tunnel barriers. A gradual competition between cotunneling enhancement of the tunneling magnetoresistance (TMR) and the TMR suppression due to the Kondo effect has been found in these junctions, with both effects having been found to coexist even in the same sample. It is possible to tune between these two states with temperature (at a temperature far below the cluster blocking temperature). In addition, when further decreasing the size of the CoPt clusters, another gradual transition between the Kondo effect and direct tunneling between the electrodes takes place. This second transition shows that the spin-flip processes found in junctions with impurities in the barrier are in fact due to the Kondo effect. A simple theoretical model able to account for these experimental results is proposed.
Ciudad D.; Arena D.; We, Z.-C.; Hindmarch, A.T.; Negusse, E.; Han, X.-F.Han; Marrows, C.H.
Nonlinear Landau-Zener tunneling in coupled waveguide arrays
The possibility of direct observation of the nonlinear Landau-Zener tunneling effect with a device consisting of two waveguide arrays connected to a tilted reduced refractive index barrier is discussed. Numerical simulations on this realistic setup are interpreted via a simplified double-well system and different asymmetric tunneling scenarios are predicted varying just the injected beam intensity.
Khomeriki, Ramaz [Physics Department, Tbilisi State University, 3 Chavchavadze, 0128 Tbilisi (Georgia) and Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzerstrasse 38, D-01187 Dresden (Germany)
What is wrong in the current models of tunneling
In this paper we show that the conventional quantum-mechanical model of a non-resonant tunneling, as a subprocess of a one-dimensional completed scattering (OCS), is non-complete. It does not allow tracing the tunneling dynamics at all stages of scattering, what makes it impossible to resolve the tunneling time problem without coming into conflict with the (macro-)causality principle. As is shown, all timekeeping procedures to underlie the tunneling-time concepts and experiments presented in the tunneling time literature (TTL) fill this gap in the current description of the tunneling dynamics by 'self-evident' assumptions which are erroneous on closer inspection. We present the alternative model of the OCS, which allows tracing the tunneling dynamics at all stages of scattering and, as a consequence, is free from those paradoxes that flood the current TTL. By this model, among two fundamental velocity concepts of the wave dynamics -- the flow velocity and the group one -- only the former can be used to determine the velocity of tunneling particles in the barrier region.
Nikolay Chuprikov
Comparison Between Field Data and NASA Ames Wind Tunnel Data
The objective of this analysis is to compare the measured data from the NASA Ames wind tunnel experiment to those collected in the field at the National Wind Technology Center (NWTC) with the same turbine configuration. The results of this analysis provide insight into what measurements can be made in the field as opposed to wind tunnel testing.
Corbus, D.
Vibration-Assisted Electron Tunneling in C140 Transistors
We measure electron tunneling in transistors made from C140, a molecule with a mass?spring?mass geometry chosen as a model system to study electron-vibration coupling. We observe vibration-assisted tunneling at an energy corresponding to the stretching mode of C140. Molecular modeling provides explanations for why this mode couples more strongly to electron tunneling than to the other internal modes of the molecule. We make comparisons between the observed tunneling rates and those expected from the Franck?Condon model. When electrons travel through molecules, vibrational modes of the molecules can affect current flow. Molecular-vibrationassisted tunneling was first measured in the 1960s using devices whose tunnel barriers contained many molecules. 1 Recently, effects of vibrations in single molecules have been measured using scanning tunneling microscopes, 2 singlemolecule transistors, 3,4 and mechanical break junctions. 5 Theoretical considerations suggest that different regimes may exist depending on whether tunneling electrons occupy resonant energy levels on the molecule, and also on the * Corresponding author.
A. N. Pasupathy; J. Park; C. Chang; A. V. Soldatov; S. Lebedkin; R. C. Bialczak; J. E. Grose; L. A. K. Donev; J. P. Sethna; D. C. Ralph; P. L. Mceuen
Langley 16-Ft. Transonic Tunnel Pressure Sensitive Paint System
This report describes the NASA Langley 16-Ft. Transonic Tunnel Pressure Sensitive Paint (PSP) System and presents results of a test conducted June 22-23, 2000 in the tunnel to validate the PSP system. The PSP system provides global surface pressure measurements ...
Sprinkle Danny R.; Obara Clifford J.; Amer Tahani R.; Leighty Bradley D.; Carmine Michael T.; Burkett Cecil G.; Sealey Bradley S.
Long-term behaviour of twin tunnels in London clay
-state settlement RT, RTi Tunnel radius, and initial value S Settlement s Deviatoric stress tensor xxxi CONTENTS s� Deviatoric stress tensor stated relative to rotated yield surface axis Sintc , S int cmid Additional Scmax(ss) due to twin-tunnel interaction...
Laver, Richard George
Saving Money in Reno's Wind Tunnels | Department of Energy
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
Money in Reno's Wind Tunnels Money in Reno's Wind Tunnels Saving Money in Reno's Wind Tunnels June 28, 2010 - 5:14pm Addthis Located in one of Reno's natural wind tunnels, City Hall proved to be the perfect location for one of the city's nine new wind turbines. | Photo courtesy of the City of Reno Located in one of Reno's natural wind tunnels, City Hall proved to be the perfect location for one of the city's nine new wind turbines. | Photo courtesy of the City of Reno On the street level in Reno, it may be easy to forget that every time the breeze blows off the Truckee River and past the 17-story City Hall, the town is quietly saving money. But the $11,000 the city is expected to save each year from wind power will be a friendly reminder. Installed in early June, the two 1.5-kilowatt wind
Saving Money in Reno's Wind Tunnels Saving Money in Reno's Wind Tunnels Saving Money in Reno's Wind Tunnels June 28, 2010 - 5:14pm Addthis Located in one of Reno's natural wind tunnels, City Hall proved to be the perfect location for one of the city's nine new wind turbines. | Photo courtesy of the City of Reno Located in one of Reno's natural wind tunnels, City Hall proved to be the perfect location for one of the city's nine new wind turbines. | Photo courtesy of the City of Reno On the street level in Reno, it may be easy to forget that every time the breeze blows off the Truckee River and past the 17-story City Hall, the town is quietly saving money. But the $11,000 the city is expected to save each year from wind power will be a friendly reminder. Installed in early June, the two 1.5-kilowatt wind
MHK Technologies/Tunneled Wave Energy Converter TWEC | Open Energy
Tunneled Wave Energy Converter TWEC Tunneled Wave Energy Converter TWEC < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage Tunneled Wave Energy Converter TWEC.jpg Technology Profile Primary Organization SeWave Ltd Project(s) where this technology is utilized *MHK Projects/TWEC Project Technology Resource Click here Wave Technology Type Click here Oscillating Water Column Technology Readiness Level Click here TRL 1-3: Discovery / Concept Definition / Early Stage Development & Design & Engineering Technology Description The Tunneled Wave Energy Converter TWEC utilizes the OWC principle through its use of a proposed bored out tunnel within a cliff side of the Faroe Islands Technology Dimensions Device Testing Date Submitted 10/8/2010 << Return to the MHK database homepage
Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes
We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.
Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)] [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)
Assessment of End-of-Life Behavior of the Surface Modification to Improve Cavitation-Erosion Resistance in the Mercury Target at the Spallation Neutron Source
The cavitation-erosion resistance of the Kolsterised{reg_sign} layer on annealed or cold-worked substrates of 316LN stainless steel has been examined in mercury using a vibratory horn technique and extended exposure periods intended to expose 'end-of-life' performance characteristics. The Kolsterised{reg_sign} layer tends to remain protective--as evidenced by modest steady-state weight loss and surface roughness increases, only isolated pitting, and limited wetting by mercury--until the protective layer has been thinned by general erosion to about 15-20 {micro}m. Prior to that amount of erosion, the cavitation-erosion resistance of both types of specimens appears defined by the properties of the protective layer. However, after thinning to such a degree, initial breakdown of the protective layer is characterized by increases in both the surface roughness and the number/depth of individual pits across the surface at a rate that is strongly dependent on the substrate condition, with annealed substrates significantly more prone to damage. However, even as the protective properties of the Kolsterised{reg_sign} layer decrease, both weight change and profile development as a function of sonication time suggest a gradual reversion to cavitation-erosion behavior similar to that of untreated substrates.
Alden Large Flume | Open Energy Information
Flume Flume Jump to: navigation, search Basic Specifications Facility Name Alden Large Flume Overseeing Organization Alden Research Laboratory, Inc Hydrodynamic Testing Facility Type Flume Length(m) 24.4 Beam(m) 6.1 Depth(m) 3.0 Water Type Freshwater Cost(per day) $5000/week Towing Capabilities Towing Capabilities Yes Maximum Velocity(m/s) 0.9 Maximum Velocity with Constriction(m/s) 3 Wavemaking Capabilities Wavemaking Capabilities Yes Maximum Wave Height(m) 0.0 Maximum Wave Height(m) at Wave Period(s) 0.0 Wave Period Range(s) 2.1 Current Velocity Range(m/s) 3.2 Programmable Wavemaking Yes Wavemaking Description Wave generators not yet designed Simulated Beach No Channel/Tunnel/Flume Channel/Tunnel/Flume Yes Recirculating Yes Wind Capabilities Wind Capabilities Yes
Construction monitoring activities in the ESF starter tunnel
In situ design verification activities am being conducted in the North Ramp Starter Tunnel of the Yucca Mountain Project Exploratory Studies Facility. These activities include: monitoring the peak particle velocities and evaluating the damage to the rock mass associated with construction blasting, assessing the rock mass quality surrounding the tunnel, monitoring the performance of the installed ground support, and monitoring the stability of the tunnel. In this paper, examples of the data that have been collected and preliminary conclusions from the data are presented.
Pott, J. [Sandia National Labs., Albuquerque, NM (United States); Carlisle, S. [Agapito (J.F.T.) and Associates, Inc., Grand Junction, CO (United States)
Thermal/mechanical analyses of G-Tunnel field experiments at Rainier Mesa, Nevada
Analysis methods (models) are currently being developed to support thermal, mechanical, and thermomechanical aspects of repository design and performance assessment of the candidate Yucca Mountain high-level nuclear waste site. Credibility of these models, and therefore of design and performance analyses, will in part be determined through comparison of calculated and measured response (validation) for large-scale field experiments. This paper discusses the models being developed, the rationale behind the model development, and analyses of experiments performed at G-Tunnel and planned as part of site characterization at Yucca Mountain. 25 refs., 21 figs.
Bauer, S.J.; Costin, L.S.; Chen, E.P.; Tillerson, J.R.
[Scanning tunnelling microscopy and spectroscopy of ceramic grain boundaries]. [Annual report, September 1992--September 1993
Objective is to study the local geometric and electronic structure at grain boundaries in oxides; this was motivated by the potential to use STM and tunneling spectroscopy on semiconducting ceramics. In order to understand the imaging of low conductivity materials, a number of transition metal oxides were examined: ZnO, TiO{sub 2}. Spatial resolution limits are considered. Conductance profiles across silicon grain boundaries are compared with those across more complex SrTiO{sub 3} grain boundaries. Calculations of space charge in complex oxides are presented. A SEM/STM was constructed which operates in ultrahigh vacuum and has large scale positioning capability (> 1 cm).
Evidence of strong-coupling superconductivity in CaC{sub 6} from tunneling spectroscopy.
Tunneling in CaC{sub 6} crystals reproducibly reveals superconducting gaps {Delta} of 2.3 {+-} 0.2 meV that are {approx}40% larger than reported earlier. In an isotropic s-wave scenario, that puts CaC{sub 6} into the class of very strongly coupled superconductors, since 2{Delta}/kT{sub c} {approx} 4.6, implying that soft Ca phonons are primarily involved in the superconductivity. This conclusion explains the relatively large Ca isotope effect found recently for CaC{sub 6}, but it could also signal a strong anisotropy in the electron-phonon interaction.
Kurter, C.; Ozyuzer, L.; Mazur, D.; Zasadzinski, J. F.; Rosenmann, D.; Claus, H.; Hinks, D. G.; Gray, K. E.; Materials Science Division; Illinois Inst. Tech.; Izmir Inst. Tech.
Icing Wind Tunnel Tests on the CSIRO Liquid Water Probe
Wet wind tunnel tests have been Performed on several versions of the CSIRO probe designed for the airborne measurement of liquid water content. Four different controller units and 17 different Probe sensors (including half-size and shielded ...
W. D. King; J. E. Dye; D. Baumgardner; J. W. Strapp; D. Huffman
Reexamination of Riming Electrification in a Wind Tunnel
Riming electrification experiments have been conducted in a wind tunnel, focusing on the substantial difference in results reported by Takahashi in 1978 and by Jayaratne et al. in 1983. Three critical regimes were selected, differing in ...
Tsutomu Takahashi; Kuniko Miyawaki
Response of continuous pipelines to tunnel induced ground deformations
This thesis develops analytical solutions for estimating the bending moments and axial loads in a buried pipeline due to ground movements caused by tunnel construction in soft ground. The solutions combine closed-form, ...
Ieronymaki, Evangelia S
Hybrid high-temperature superconductor-semiconductor tunnel diode
We report the demonstration of hybrid high-Tc-superconductor-semiconductor tunnel junctions, enabling new interdisciplinary directions in condensed matter research. The devices were fabricated by our newly-developed mechanical bonding technique, resulting in high-Tc-semiconductor planar junctions acting as superconducting tunnel diodes. Tunneling-spectra characterization of the hybrid junctions of Bi2Sr2CaCu2O8+{\\delta} combined with bulk GaAs, or a GaAs/AlGaAs quantum well, exhibits excess voltage and nonlinearity - in good agreement with theoretical predictions for a d-wave superconductor-normal material junction, and similar to spectra obtained in scanning tunneling microscopy. Additional junctions are demonstrated using Bi2Sr2CaCu2O8+{\\delta} combined with graphite or Bi2Te3. Our results pave the way for new methods in unconventional superconductivity studies, novel materials and quantum technology applications.
Alex Hayat; Parisa Zareapour; Shu Yang F. Zhao; Achint Jain; Igor G. Savelyev; Marina Blumin; Zhijun Xu; Alina Yang; G. D. Gu; Harry E. Ruda; Shuang Jia; R. J. Cava; Aephraim M. Steinberg; Kenneth S. Burch
A Vertical Wind Tunnel for Snow Process Studies
A vertical wind tunnel using an artificially generated supercooled cloud was constructed to study snowfall processes. It is 18 m high and operates to a temperature as low as ?25�C. Ultrasonic atomizers supply the supercooled water droplets, and ...
Tsuneya Takahashi; Chikara Inoue; Yoshinori Furukawa; Tatsuo Endoh; Renji Naruse
Superluminal tunneling of microwaves in smoothly varying transmission lines
Tunneling of microwaves through a smooth barrier in a transmission line is considered. In contrast to standard wave barriers, we study the case where the dielectric permittivity is positive, and the barrier is caused by the inhomogeneous dielectric profile. It is found that reflectionless, superluminal tunneling can take place for waves with a finite spectral width. The consequences of these findings are discussed, and an experimental setup testing our predictions is proposed.
Shvartsburg, A B; Brodin, G; Stenflo, L
Brookhaven and the Large Hadron Collider
Brookhaven & the Large Hadron Collider Brookhaven & the Large Hadron Collider Home News Brookhaven & ATLAS ATLAS ATLAS Calorimeter ATLAS Muon Spectrometer Construction Computing Upgrades RHIC & LHC Education LHC tunnel ATLAS detector ATLAS detector RACF BNL built superconducting magnets Brookhaven & the LHC The world's most powerful particle accelerator, the Large Hadron Collider (LHC) in Switzerland, powers unprecedented explorations of the deepest mysteries of the universe. In addition to serving as the U.S. host laboratory for the ATLAS experiment at the LHC, Brookhaven National Lab plays multiple roles in this international collaboration, from construction and project management to data storage and distribution. ATLAS rendering Brookhaven and ATLAS Brookhaven physicists and engineers are participating in one of the most
Getting Traffic Lights Talking to Improve Topeka's Traffic Tunnel |
Getting Traffic Lights Talking to Improve Topeka's Traffic Tunnel Getting Traffic Lights Talking to Improve Topeka's Traffic Tunnel Getting Traffic Lights Talking to Improve Topeka's Traffic Tunnel October 8, 2010 - 11:16am Addthis Topeka is using Recovery Act funding to resynchronize 22 traffic lights. | Photo by Linda Voss Topeka is using Recovery Act funding to resynchronize 22 traffic lights. | Photo by Linda Voss Lindsay Gsell The five-lane 21st street corridor in Topeka is a hub for restaurants, shopping and entertainment. "This is where everyone in Topeka goes to shop," says Topeka resident Linda Voss. In addition to food and fun, the one-mile corridor is home to seven traffic lights-and for drivers, a potential traffic stop every 754 feet, or a little more than two football fields. "The traffic signals are a challenge to time in this area," says Voss,
Calibration of Johnson�Williams and PMS ASSP Probes in a Wind Tunnel
Wet wind tunnel tests have provided calibrations and intercomparisons of the LAMP's cloud liquid water content probes (three Johnson�Williams sensor heads and one PMS ASSP). The tunnel liquid water content was deduced with a rotating cyclinder ...
J. F. Gayet
Development of the resource model for the Decision Aids for Tunneling (DAT)
The Decision Aids for Tunneling (DAT) are a computer based method with which distributions of tunnel construction time and cost as well as required and produced resources can be estimated considering uncertainties in ...
Min, Sangyoon, 1973-
Calibrations of Johnson-Williams Liquid Water Content Meters in a High-Speed Icing Tunnel
Wind tunnel tests have provided calibrations and intercomparisons of 14 Johnson-Williams (J�W) cloud liquid water content (LWC) measuring devices with 23 sensor heads from 10 research organizations. The absolute tunnel LWC was deduced using a ...
J. Walter Strapp; Robert S. Schemenauer
Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks
[1] Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel ...
Butscher, Christoph
Wind Tunnel Tests of the Airborne PVM-100A Response to Large Droplets
The Gerber Scientific, Inc. Particle Volume Monitor (PVM) is widely used to measure the liquid water content (LWC) and droplet effective radius (reff) of water clouds. The LWC response of the airborne version of this instrument, the PVM-100A, was ...
M. Wendisch; T. J. Garrett; J. W. Strapp
Results of pressurized-slot measurements in the G-Tunnel underground facility
A rock-mechanics field-testing program is underway at Sandia National Laboratories (SNL) as part of the YMP. SNL has the responsibility for assessing the repository design and performance as well as characterizing the geomechanical behavior of the rock. SNL has conducted field experiments in G-Tunnel in Rainier Mesa at the NTS, where tuffs similar to those at Yucca Mountain, the potential repository site, are found. Later experiments are planned as part of the YMP Exploratory Shaft investigations at Yucca Mountain. Major geomechanical factors in repository developments are determinations of the stress state and the deformability of the rock mass (described by the modulus of deformation). One feature of SNL`s rock-mechanics program was the development of a testing program for cutting thin slots in a jointed welded tuff and utilizing flatjacks for pressurizing these thin-slots on a relatively, large scale. Objectives in the pressurized-slot testing in G-Tunnel have been to apply and possibly improve methods for (1) utilizing the flatjack cancellation (FC) method for measuring stresses normal to the slot and (2) measuring the modulus of deformation of the jointed rock surrounding the slot. This paper discusses the results of field measurements in and around a single slot and evaluates potential applications and limitations. 10 refs., 1 fig., 4 tabs.
Zimmerman, R.M.; Mann, K.L.; Dodds, D.J.
A portable vacuum hammer seismic source for use in tunnel environments
Concern for the measurement of seismic refraction velocities in tunnel areas where cables, construction features, and other sensitive structures render the use of dynamite sources unwise, resulted in the design of a vacuum-driven impact system utilizing a 43-kg (94-lb) weight in a 2-m (6.5-ft) tube. The system is portable, quickly assembled and disassembled, and requires only standard electrical power, an air pressure supply, and a laboratory vacuum pump to operate. The maximum weight of any component is 84 kg (185 lb), the remaining components being significantly lighter. Tests in volcanic rock tunnels in Rainier Mesa at the Nevada Test Site indicate maximum energy generated by the system is in the SV wave. When the system was employed at angles other than vertical, a polarized SH mode was also observed. The hammer was used to obtain velocities in an in-hole survey in a 138-m horizontal hole drilled behind the flat face of the Red Hot chamber after the Red Hot nuclear detonation. A large decrease was observed in compressional velocity compared with pre-event values. Because 20 years have elapsed since the explosion, one cannot separate the effect of ground shock on lowering the velocity from possible effects of destressing around adjacent underground openings over this period.
Carroll, R.D.; Magner, J.E.
Hot-electron generation by 'cavitating' Langmuir turbulence in the nonlinear stage of the two-plasmon-decay instability
The kinetic reduced-description particle-in-cell simulation technique has been applied to study the nonlinear stage of two-plasmon-decay (TPD) instability in an inhomogeneous plasma driven by crossed laser beams. The TPD instability is found to be a prolific generator of 'cavitating' Langmuir turbulence. Langmuir 'cavitons'-localized longitudinal electric fields, oscillating near the local electron plasma frequency, trapped in ponderomotive density depressions-collapse to dimensions of a few electron Debye lengths, where the electric field energy is collisionlessly transferred to electron kinetic energy. The resulting hot electrons can attain instantaneous temperatures up to 100 keV with net suprathermal heat flux out of the system of up to a few percent of the input laser energy. Scaling laws for this hot-electron generation by TPD, in regimes motivated by recent experiments on the Omega laser, were presented recently by Vu et al. (H. X. Vu, D. F. DuBois, D. A. Russell, and J. F. Myatt, Phys. Plasmas 19, 102703 (2012)). This paper concentrates on the microscopic mechanisms for hot-electron generation. The spatial distribution of the maxima of the electric field envelope modulus is found to be very spiky, with the distribution of electric field envelope maxima obeying Gaussian statistics. The cavitons are produced in density-depletion trenches produced by the combined ponderomotive interference of the crossed laser beams and the ponderomotive beats of the primary backward-going TPD Langmuir waves (LWs) resulting from the crossed beams. The Langmuir turbulence is strongest in the electron-density region near 0.241 Multiplication-Sign the laser's critical density, where the forward LWs from the crossed-beam TPD are degenerate. Nucleation of cavitons is assisted by the modulation of the electron density in the trenches, which in turn is caused by the beating of the common forward-going LW and the pair of backward-going LWs. The autocorrelation function of the LW envelope field provides a near-universal shape for intense cavitons-in the neighborhood of the local field maxima. The hot-electron temperature is found to be approximately a linear function of the 'caviton temperature' determined from the Gaussian distribution of caviton maxima. These diagnostics provide strong evidence for the importance of Langmuir caviton collapse in the generation of hot electrons by TPD. Extended Zakharov model predictions for TPD exhibit the same qualitative phenomena.
Vu, H. X. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); DuBois, D. F. [Lodestar Research Corporation, Boulder, Colorado 80301 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Russell, D. A. [Lodestar Research Corporation, Boulder, Colorado 80301 (United States); Myatt, J. F. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)
Incompatibility of the tunneling limit with laser fields
The Schwinger limit refers to longitudinal electric fields that are sufficiently strong to "polarize the vacuum" into electron-positron pairs by a tunneling mechanism. Laser fields are transverse electromagnetic fields for which the Schwinger limit has no relevance. Longitudinal and transverse fields are fundamentally different because of the different values of the F^{{\\mu}{\
H. R. Reiss
Improved tunnel resistance of silvered-polymer mirrors
This report documents the research performed at the Solar Energy Research Institute during fiscal year (FY) 1991 to develop ways to prevent delamination failure (known as tunneling) of silvered-polymer reflector materials. Several promising approaches have been identified and demonstrated that substantially reduce such failures. These approaches include (1) use of Tedlar edge tape rather than the manufacturer-recommended ECP-244 tape, (2) thermal treatment of laminated reflector/substrate constructions, and (3) application of silver to the polymer film through an alternative deposition process. Approaches 1 and 2 offer readily available engineering solutions to the delamination problem. Approaches 2 and 3 provide tunnel resistance over the entire surface of the reflector material, including the edges. Tedlar (a polyvinyl fluoride from DuPont) tape is an opaque white tape available in different widths from 3M Company. The base material has demonstrated outstanding outdoor durability. Thermal treatment of ECP-305 laminated to substrate materials has demonstrated outstanding resistance to tunneling. Alternative silver deposition techniques such as sputtering (rather than thermal evaporation) offer increased resistance to tunneling. 15 refs., 10 figs.
Jorgensen, G.; Schissel, P.; Kennedy, C.; Shinton, Y.; Powell, D.; Siebarth, J.
Tunnel junction multiple wavelength light-emitting diodes
A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect.
Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO)
A Cross-Platform for Tunnel Blast Design and Simulation
Digital Mine has become the inevitable development trend of the future mines. Blasting is a essential process during the exploration and development of practical mining engineering. The blasting always plays a direct influence on the efficiency of each ... Keywords: Digital Mine, Blasting parameters, Parameters design, Tunnel blast design, Cross-platform
Tingting Zhu; Chao Wang; Mingmin Zhang; Zhigeng Pan
Coherent resonant tunneling through an artificial molecule C. A. Stafford
Coherent resonant tunneling through an artificial molecule C. A. Stafford Fakulta¨t fu¨r Physik PRB 58C. A. STAFFORD, R. KOTLYAR, AND S. DAS SARMA #12;Coulomb blockade12 for C Cg to a ballistic /e 1 follows from the particle-hole symmetry of Eq. 1 . 7094 PRB 58C. A. STAFFORD, R. KOTLYAR, AND S
Stafford, Charles
High-Lift Flight Tunnel---Phase II Report
The High-Lift Flight Tunnel (HiLiFT) concept is a revolutionary approach to aerodynamic ground testing. This concept utilizes magnetic levitation and linear motors to propel an aerodynamic model through a tube containing a quiescent test medium. This ...
Lofftus David; Lund Thomas; Rote Donald
Laboratory and Wind Tunnel Evaluations of the Rosemount Icing Detector
The Rosemount model 871FA ice detector was evaluated during a number of laboratory and wind tunnel studies. The purpose of this evaluation was to determine the sensitivity of the detector to a variety of icing conditions and to determine its ...
Darrel Baumgardner; Alfred Rodi
Macroscopic quantum tunnelling in a current biased Josephson junction
We discuss in this work an attempt to answer experimentally the question: do macroscopic variables obey quantum mechanics. More precisely, this experiment deals with the question of quantum-mechanical tunnelling of a macroscopic variable, a subject related to the famous Schrodinger's cat problem in the theory of measurement.
Martinis, J.M.; Devoret, M.H.; Clarke, J.; Urbina, C.
Safety analysis of natural gas vehicles transiting highway tunnel
A safety analysis was performed to assess the relative hazard of compressed natural gas (CNG) fueled vehicles traveling on various tunnels and bridges in New York City. The study considered those hazards arising from the release of fuel from CNG vehicles ranging in size from a passenger sedan to a full size 53 passenger bus. The approach used was to compare the fuel hazard of CNG vehicles to the fuel hazard of gasoline vehicles. The risk was assessed by estimating the frequency of occurrence and the severity of the hazard. The methodology was a combination of analyzing accident data, performing a diffusion analysis of the gas released in the tunnel and determining the consequences of ignition. Diffusion analysis was performed using the TEMPEST code for various accident scenarios resulting in CNG release inside the Holland Tunnel. The study concluded that the overall hazard of CNG vehicles transiting a ventilated tunnel is less than the hazard from a comparable gasoline fueled vehicle. 134 refs., 23 figs., 24 tabs.
Shaaban, S.H.; Zuzovsky, M.; Anigstein, R.
A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect. 5 figs.
Olson, J.M.; Kurtz, S.R.
Pressurized Icing Tunnel for Graupel, Hail and Secondary Raindrop Production
The closed-circuit icing wind tunnel with pressure control serves for experiments on the growth and melting of ice particles, such as graupel and hailstones, and the observation of shedding of rain-sized drops by growing and melting hailstones. ...
Roland List; G. B. Lesins; F. Garc�a-Garc�a; D. B. McDonald
Polarization-engineered GaN/InGaN/GaN tunnel diodes
We report on the design and demonstration of polarization-engineered GaN/InGaN/GaN tunnel junction diodes with high current density and low tunneling turn-on voltage. Wentzel-Kramers-Brillouin (WKB) calculations were used to model and design tunnel junctions with narrow bandgap InGaN-based barrier layers. N-polar p-GaN/In0.33Ga0.67N/n-GaN heterostructure tunnel diodes were grown using molecular beam epitaxy. Efficient zero bias tunneling turn-on with a high current density of 118 A/cm2 at a reverse bias of 1V, reaching a maximum current density up to 9.2 kA/cm2 were obtained. These results represent the highest current density reported in III-nitride tunnel junctions, and demonstrate the potential of III-nitride tunnel devices for a broad range of optoelectronic and electronic applications.
Sriram Krishnamoorthy; Digbijoy N. Nath; Fatih Akyol; Pil Sung Park; Michele Esposto; Siddharth Rajan
Augmentation of SPICE for Simulation of Circuits Containing Resonant Tunneling Diodes
This paper describes the incorporation of an accurate physics-based model of the resonant tunneling diode (RTD) into Berkeley SPICE version 3F5 and addresses the related direct current (dc) and transient convergence problems caused by the negative differential resistance (NDR) and the exponential nature of the device characteristics. To circumvent the dc convergence problems, a new continuation technique using artificial parameter embedding and a current limiting algorithm are proposed. The studies made in this paper have shown that these techniques are superior to the in-built continuation methods of SPICE, such as Gmin-stepping and Source-stepping, for a large number of circuits of varying sizes. To improve transient convergence performance, the following three algorithms are added to SPICE: a modified forced-convergence algorithm, a new time-step adjustment algorithm, and a modified device voltage prediction algorithm.
Mayukh Bhattacharya; et al.
Accuracy of the Frensley inflow boundary condition for Wigner equations in simulating resonant tunneling diodes
In this paper, the accuracy of the Frensley inflow boundary condition of the Wigner equation is analyzed in computing the I-V characteristics of a resonant tunneling diode (RTD). It is found that the Frensley inflow boundary condition for incoming electrons holds only exactly infinite away from the active device region and its accuracy depends on the length of contacts included in the simulation. For this study, the non-equilibrium Green's function (NEGF) with a Dirichlet to Neumann mapping boundary condition is used for comparison. The I-V characteristics of the RTD are found to agree between self-consistent NEGF and Wigner methods at low bias potentials with sufficiently large GaAs contact lengths. Finally, the relation between the negative differential conductance (NDC) of the RTD and the sizes of contact and buffer in the RTD is investigated using both methods.
Jiang Haiyan [Department of Applied Mathematics, Beijing Institute of Technology, Beijing 100081 (China); Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States); Cai Wei, E-mail: firstname.lastname@example.com [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States); Tsu, Raphael [Department of Electrical and Computer Engineering, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States)
Property:Special Physical Features | Open Energy Information
Physical Features Physical Features Jump to: navigation, search Property Name Special Physical Features Property Type Text Pages using the property "Special Physical Features" Showing 25 pages using this property. (previous 25) (next 25) C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + The 2-Foot Variable Pressure Cavitation Water Tunnel is a vertical plane, closed recirculating, variable-speed, variable-pressure, open jet test section, closed jet test section, and semi-rectangular test section. Carderock 3-ft Variable Pressure Cavitation Water Tunnel + The 3-ft Variable Pressure Cavitation Water Tunnel is a vertical plane, closed recirculating with resorber, variable-speed, variable-pressure, two interchangeable circular test sections. Carderock Circulating Water Channel + The Circulating Water Channel is a vertical plane, open to the atmosphere test section with a free surface in a closed recirculating water circuit, variable speed, rectangular cross-sectional shape facility. There are 10 large viewing windows on either side of the test section at different elevations and 9 in the bottom; movable bridge spans the test section for ease and versatility in mounting models, rigging bridge is capable of taking towing loads at any one of numerous points up to 35,584 N
A Model for the Behavior of Magnetic Tunnel Junctions
A magnetic tunnel junction is a device that changes its electrical resistance with a change in an applied magnetic field. A typical junction consists of two magnetic electrodes separated by a nonmagnetic insulating layer. The magnetizations of the two electrodes can have two possible extreme configurations, parallel and antiparallel. The antiparallel configuration is observed to have the higher measured resistance and the parallel configuration has the lower resistance. To switch between these two configurations a magnetic field is applied to the device which is primarily used to change the orientation of the magnetization of one electrode usually called the free layer, although with sufficient high magnetic field the orientation of the magnetizations of both of the electrodes can be changed. The most commonly used models for describing and explaining the electronic behavior of tunnel junctions are the Simmons model and the Brinkman model. However, both of these models were designed for simple, spin independent tunneling. The Simmons model does not address the issue of applied magnetic fields nor does it address the form of the electronic band structure in the metallic electrodes, including the important factor of spin polarization. The Brinkman model is similar, the main difference between the two models being the shape of the tunneling barrier potential between the two electrodes. Therefore, the research conducted in this thesis has developed a new theoretical model that addresses these important issues starting from basic principles. The main features of the new model include: the development of equations for true spin dependent tunneling through the insulating barrier, the differences in the orientations of the electrode magnetizations on either side of the barrier, and the effects of the density of states function on the behavior of the junction. The present work has explored densities of states that are more realistic than the simplified free electron density of states function, and has developed an exact analytic solution for the case of an electron band of finite width. The approach taken in this thesis easily allows extension to cases where the band structure is different on either side of the barrier (known as heterojunctions) which are of greater interest in real magnetic tunnel junction devices rather than the simple, identical band structure devices.
Bryan John Baker
Low-Frequency Electromagnetic Backscatter from Buried Tunnels
This progress report is submitted under a contract between the Special Project Office of DARPA and Lawrence Livermore National Laboratory. The Project Manager at DARPA is Dr. Michael Zatman. Our purpose under this contract is to investigate interactions between electromagnetic waves and a class of buried targets located in multilayered media with rough interfaces. In this report, we investigate three preliminary problems. In each case our specific goal is to understand various aspects of the electromagnetic wave interaction mechanisms with targets in layered media. The first problem, discussed in Section 2, is that of low-frequency electromagnetic backscattering from a tunnel that is cut into a lossy dielectric half-space. In this problem, the interface between the upper (free space) region and the lower (ground) region is smooth. The tunnel is assumed to be a cylindrical free-space region of infinite extent in its axial direction and with a diameter that is small in comparison to the free-space wavelength. Because its diameter is small, the tunnel can be modeled as a buried ''wire'' described by an equivalent impedance per unit length. In Section 3 we extend the analysis to include a statistically rough interface between the air and ground regions. The interface is modeled as a random-phase screen. Such a screen reduces the coherent power in a plane wave that is transmitted through it, scattering some of the total power into an incoherent field. Our analysis of this second problem quantifies the reduction in the coherent power backscattered from the buried tunnel that is caused by the roughness of the air-ground interface. The problem of low-frequency electromagnetic backscattering from two buried tunnels, parallel to each other but at different locations in the ground, is considered in Section 4. In this analysis, we wish to determine the conditions under which the presence of more than one tunnel can be detected via backscattering. Section 5 concludes the report with a summary of the investigations discussed herein and recommendations for future work on problems of this class.
Casey, K; Pao, H
Examination of Compatibility of Potentially Cavitation-Resistant Modifications of Type 316LN Stainless Steel with Mercury in a Thermal Convection Loop
A 316L stainless steel thermal convection loop (TCL) containing a variety of stainless steel coupons circulated mercury for 2000 h. The TCL conditions included a maximum temperature of 307 C, a maximum temperature gradient of 90 C, and a Hg velocity of about 1.4 m/min. In addition to mill-annealed/surface-ground 316LN coupons serving as the baseline material, other coupons included 316LN that was 50% cold-worked, 316LN that was given a proprietary surface hardening treatment termed ''kolsterizing,'' and Nitronic 60. The purpose of this test was to examine Hg compatibility with these modest variations of annealed 31 6LN stainless steel that are considered potential improvements over annealed 31 6LN for cavitation-erosion resistance in the Spallation Neutron Source (SNS) target containment system. The results indicated negligible weight change for each coupon type, no significant indication of attack or surface roughening, and generally no interaction with Hg.
Pawel, SJ
A Wind Tunnel and Theoretical Study of the Melting Behavior of Atmospheric Ice Particles. I: A Wind Tunnel Study of Frozen Drops of Radius < 500 ?m
A study has been made on the melting behavior of frozen drops suspended freely at terminal velocity in the UCLA Cloud Tunnel. The relative humidity of the air ranged between 25 and 95%. The warming rates of the tunnel air stream ranged from 2 to ...
R. Rasmussen; H. R. Pruppacher
Small Corrections to the Tunneling Phase Time Formulation
After reexamining the above barrier diffusion problem where we notice that the wave packet collision implies the existence of {\\em multiple} reflected and transmitted wave packets, we analyze the way of obtaining phase times for tunneling/reflecting particles in a particular colliding configuration where the idea of multiple peak decomposition is recovered. To partially overcome the analytical incongruities which frequently rise up when the stationary phase method is adopted for computing the (tunneling) phase time expressions, we present a theoretical exercise involving a symmetrical collision between two identical wave packets and a unidimensional squared potential barrier where the scattered wave packets can be recomposed by summing the amplitudes of simultaneously reflected and transmitted wave components so that the conditions for applying the stationary phase principle are totally recovered. Lessons concerning the use of the stationary phase method are drawn.
Alex E. Bernardini
Probing water structures in nanopores using tunneling currents
We study the effect of volumetric constraints on the structure and electronic transport properties of distilled water in a nanopore with embedded electrodes. Combining classical molecular dynamics simulations with quantum scattering theory, we show that the structural motifs water assumes inside the pore can be probed directly by tunneling. In particular, we show that the current does not follow a simple exponential curve at a critical pore diameter of about 8 {\\AA}, rather it is larger than the one expected from simple tunneling through a barrier. This is due to a structural transition from bulk-like to "nanodroplet" water domains. Our results can be tested with present experimental capabilities to develop our understanding of water as a complex medium at nanometer length scales.
P. Boynton; M. Di Ventra
Hanford facility dangerous waste permit application, PUREX storage tunnels
The Hanford Facility Dangerous Waste Permit Application is considered to be a single application organized into a General Information Portion (document number DOE/RL-91-28) and a Unit-Specific Portion. The scope of the Unit-Specific Portion is limited to Part B permit application documentation submitted for individual, operating treatment, storage, and/or disposal units, such as the PUREX Storage Tunnels (this document, DOE/RL-90-24). Both the General Information and Unit-Specific portions of the Hanford Facility Dangerous Waste Permit Application address the content of the Part B permit application guidance prepared by the Washington State Department of Ecology (Ecology 1996) and the US Environmental Protection Agency (40 Code of Federal Regulations 270), with additional information needs defined by the Hazardous and Solid Waste Amendments and revisions of Washington Administrative Code 173-303. For ease of reference, the Washington State Department of Ecology alpha-numeric section identifiers from the permit application guidance documentation (Ecology 1996) follow, in brackets, the chapter headings and subheadings. A checklist indicating where information is contained in the PUREX Storage Tunnels permit application documentation, in relation to the Washington State Department of Ecology guidance, is located in the Contents Section. Documentation contained in the General Information Portion is broader in nature and could be used by multiple treatment, storage, and/or disposal units (e.g., the glossary provided in the General Information Portion). Wherever appropriate, the PUREX Storage Tunnels permit application documentation makes cross-reference to the General Information Portion, rather than duplicating text. Information provided in this PUREX Storage Tunnels permit application documentation is current as of April 1997.
Price, S.M.
The development of magnetic tunnel junction fabrication techniques
. The effect of grain size, shape, voltage bias, temperature, layer thickness and roughness should be understood and controllable, in order to produce reproducible junctions. The most problematic requirement has been that of low resistance. Magnetic tunnel... . The effect of roughness, aluminium thickness and voltage on the number of pinholes and weak-links per unit area was studied. High frequency testing of read heads at wafer level was performed with a network analyser. Design implications for read head...
Elwell, Clifford Alastair
Investigation of Data Quality for Wind Tunnel Internal Balance Testing
Achieving high quality, consistency, and testing efficiency in wind tunnel tests using internal balances is accomplished through the use of new testing methods, analysis of data output, and standardized documentation of test procedures at the Texas A&M Low Speed Wind Tunnel. The wind tunnel is capable of performing internal balance testing on models that experience less than 500 pounds of normal force. Testing has shown less than a 3% mean flow variation with the sting mount installed and a turbulence intensity of less than 0.25%. Documentation of procedures and check- lists for installation of internal balance testing equipment and test execution provide higher efficiency and consistency during a test. A step-by-step examination of the data analysis routines and associated uncertainty equations show uncertainty in the force and moment coefficients for the Mark XIII internal balance to be approximately � 0.05 and � 0.02, respectively. Quantifying the uncertainty of the primary output parameters and showing repeatability of the data within the defined uncertainty limits achieved higher quality results.
Hidore, John Preston
On the Relation between Perfect Tunneling and Band Gaps for SNG Metamaterial Structures
In this article we have proposed a compact classification of isotropic and homogenous single negative (SNG) electromagnetic metamaterial based perfect tunneling unit cells. This has been made by means of the band gap theories and properties of the arrays made up of these unit cells. Based on their reported characteristics, we have proposed new structures that simultaneously show perfect tunneling band and complete band gap (CBG - omni directional stop band for both polarizations). Besides, we have identified perfect tunneling which can be considered as "phase shifted perfect tunneling". Several interesting and new phenomena like Complete Perfect Tunneling (CPT - omni-directional perfect tunneling for both polarizations), Band Gap Shifting, CBG in Double Positive (DPS) material range, etc. have been reported with proper physical and mathematical explanations.
Mahdy, M R C; Shawon, Jubayer; Al-Quaderi, Golam Dastegir; Matin, M A
Baker-Barry Tunnel Lighting: Evaluation of a Potential GATEWAY Demonstrations Project
The U.S. Department of Energy (DOE) is evaluating the Baker-Barry Tunnel as a potential GATEWAY Demonstrations project for deployment of solid-state lighting (SSL) technology. The National Park Service (NPS) views this project as a possible proving ground and template for implementation of light-emitting diode (LED) luminaires in other NPS tunnels, thereby expanding the estimated 40% energy savings from 132 MWh/yr for this tunnel to a much larger figure national
Tuenge, Jason R.
Facility Closure Report for T-Tunnel (U12t), Area 12, Nevada Test Site, Nevada
This Facility Closure Report (FCR) has been prepared to document the actions taken to permanently close the remaining accessible areas of U12t-Tunnel (T-Tunnel) in Area 12 of the Nevada Test Site (NTS). The closure of T-Tunnel was a prerequisite to transfer facility ownership from the Defense Threat Reduction Agency (DTRA) to the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO). Closure of the facility was accomplished with the cooperation and concurrence of both NNSA/NSO and the Nevada Division of Environmental Protection (NDEP). The purpose of this FCR is to document that the closure of T-Tunnel complied with the closure requirements specified in the Facility Closure Plan for N- and T-Tunnels Area 12, Nevada Test Site (Appendix D) and that the facility is ready for transfer to NNSA/NSO. The Facility Closure Plan (FCP) is provided in Appendix D. T-Tunnel is located approximately 42 miles north of Mercury in Area 12 of the NTS (Figure 1). Between 1970 and 1987, T-Tunnel was used for six Nuclear Weapons Effects Tests (NWETs). The tunnel was excavated horizontally into the volcanic tuffs of Rainier Mesa. The T-Tunnel complex consists of a main access drift with two NWET containment structures, a Gas Seal Plug (GSP), and a Gas Seal Door (GSD) (Figure 2). The T-Tunnel complex was mothballed in 1993 to preserve the tunnel for resumption of testing, should it happen in the future, to stop the discharge of tunnel effluent, and to prevent unauthorized access. This was accomplished by sealing the main drift GSD.
NSTec Environmental Restoration
MISTY ECHO Tunnel Dynamics Experiment--Data report: Volume 1; Yucca Mountain Site Characterization Project
Tunnel damage resulting from seismic loading is an important issue for the Yucca Mountain nuclear waste repository. The tunnel dynamics experiment was designed to obtain and document ground motions, permanent displacements, observable changes in fracture patterns, and visible damage at ground motion levels of interest to the Yucca Mountain Project. Even though the maximum free-field loading on this tunnel was 28 g, the damage observed was minor. Fielding details, data obtained, and supporting documentation are reported.
Phillips, J.S.; Luke, B.A.; Long, J.W.; Lee, J.G.
MISTY ECHO tunnel dynamics experiment data report; Volume 2, Appendices: Yucca Mountain Site Characterization Project
Scanning tunneling optical resonance microscopy applied to indium arsenide quantum dot structures.
??The technique of Scanning Tunneling Optical Resonance Microscopy (STORM) has been investigated for use on nanostructures. It has been demonstrated as a viable technique to� (more)
Byrnes, Daniel P.
How Does Law Affect Finance? An Examination of Financial Tunneling in an Emerging Market
How Does Law Affect Finance? An Examination of FinancialWilliam Davidson Institute. How Does Law Affect Finance? Anfinancial tunneling, Prior work does not distinguish between
Black, Bernard; Atanasov, Vladimir; Ciccotello, Conrad S.; Gyoshev, Stanley B.
Optimization of light emitting diodes based on bipolar double-barrier resonant-tunneling structures
A bipolar double-barrier resonant-tunneling light emitting diode will have maximum emitted light intensity if (1) electrons and holes simultaneously resonant-tunnel into the quantum well, (2) the charge carriers are entirely trapped in the well as the ... Keywords: Poisson equation, Schrodinger equation, automated computer code, bipolar double-barrier RTD structures, charge carriers, chemical compositions, doping profiles, electroluminescence, electroluminescence spectrum profile, electron-hole recombination, electron-hole recombination rate, geometric structures, light emitting diodes, near zero-field condition, optimisation, quantum well, resonant tunnelling diodes, resonant-tunneling LED, semiconductor device models, semiconductor quantum wells, temperature stability, theoretical modeling, thermal stability
A. Kindlihagen; K. A. Chao; M. Willander; J. Genoe
EE2, Regrown InGaAs Tunnel Junctions for TFETs - Programmaster ...
CBr4 and elemental Si were used as the dopant sources in the MBE ... Current-voltage (I-V) characteristics of regrown tunnel junctions on the�...
Vital Alert's C1000 mine and tunnel radios use magnetic induction...
Vital Alert's C1000 mine and tunnel radios use magnetic induction, advanced digital communications techniques and ultra-low frequency transmission to wirelessly provide...
Interaction-induced fractional Bloch and tunneling oscillations
We study the dynamics of few interacting bosons in a one-dimensional lattice with dc bias. In the absence of interactions the system displays single-particle Bloch oscillations. For strong interaction the Bloch oscillation regime re-emerges with fractional Bloch periods which are inversely proportional to the number of bosons clustered into a bound state. The interaction strength affects the oscillation amplitude. Excellent agreement is found between numerical data and a composite particle dynamics approach. For specific values of the interaction strength, a particle will tunnel from the interacting cloud to a well-defined distant lattice location.
Khomeriki, Ramaz [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Physics Department, Tbilisi State University, Chavchavadze 3, 0128 Tbilisi (Georgia); Krimer, Dmitry O.; Haque, Masudul; Flach, Sergej [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany)
Tunneling through a parabolic barrier viewed from Wigner phase space
We analyze the tunneling of a particle through a repulsive potential resulting from an inverted harmonic oscillator in the quantum mechanical phase space described by the Wigner function. In particular, we solve the partial differential equations in phase space determining the Wigner function of an energy eigenstate of the inverted oscillator. The reflection or transmission coefficients $R$ or $T$ are then given by the total weight of all classical phase space trajectories corresponding to energies below, or above the top of the barrier given by the Wigner function.
D. M. Heim; W. P. Schleich; P. M. Alsing; J. P. Dahl; S. Varro
Results from Point Contact Tunnelling Spectroscopy and Atomic Layer Deposition
We have shown previously that magnetic niobium oxides can influence the superconducting density of states at the surface of cavity-grade niobium coupons. We will present recent results obtained by Point Contact Tunneling spectroscopy (PCT) on coupons removed from hot and cold spots in a niobium cavity, as well as a comparative study of magnetic oxides on mild baked/unbaked electropolished coupons. We will also describe recent results obtained from coated cavities, ALD films properties and new materials using Atomic Layer Deposition (ALD).
Proslier, Th. [Illinois Institute of Technology; Zasadzinski, J. [Illinois Institute of Technology; Ciovati, Gianluigi [JLAB; Kneisel, Peter K. [JLAB; Elam, J. W. [ANL; Norem, J. [ANL; Pellin, M. J. [ANL
Wind Tunnel and Field Test of Three 2D Sonic Anemometers
Wind Tunnel and Field Test of Three 2D Sonic Anemometers Wiel Wauben R&D Information and Observation Technology, KNMI September 17, 2007 #12;#12;Wind Tunnel and Field Test of Three 2D Sonic.....................................................................................................1 2. Wind sensors
Stoffelen, Ad
Performance of a Counterflow Virtual Impactor in the NASA Icing Research Tunnel
A counterflow virtual impactor (CVI) designed for aircraft use was evaluated at the NASA Icing Research Tunnel in Cleveland, Ohio. Tests were conducted for tunnel speeds of 67 and 100 m s?1, for liquid water contents of 0.23�1.4 g m?3, and for a ...
C. H. Twohy; J. W. Strapp; M. Wendisch
Acoustic Survey of a 3/8-Scale Automotive Wind Tunnel
An acoustic survey that consists of insertion loss and flow noise measurements was conducted at key locations around the circuit of a 3/8-scale automotive acoustic wind tunnel. Descriptions of the test, the instrumentation, and the wind tunnel facility ...
Jr Earl R. Booth; Romberg Gary; Hansen Larry; Lutz Ron
A magnetic tunnel junction based zero standby leakage current retention flip-flop
Recently, a magnetic tunnel junction (MTJ), which is a strong candidate as a next-generation memory element, has been used not only as a memory cell but also in spintronics logic because of its excellent properties of nonvolatility, no silicon area occupation, ... Keywords: magnetic tunnel junction (MTJ) logic, nonvolatile flip-flop, retention flip-flop, spintronics logic
Kyungho Ryu, Jisu Kim, Jiwan Jung, Jung Pill Kim, Seung H. Kang, Seong-Ook Jung
Performing bitwise logic operations in cache using spintronics-based magnetic tunnel junctions
Recent exciting developments in the emerging field of spintronics have enabled rapid advances in spintronic devices such as magnetic tunnel junctions (MTJs). While MTJs are being primarily used as the basic devices in non-volatile memory, they have also ... Keywords: magnetic tunnel junctions, spintronic logic functions, spintronics logic in memory
Shruti Patil; David J. Lilja
Novel Resonant-Tunneling Multiple-Threshold Logic Circuit Based on Switching Sequence Detection
We present a novel multiple-threshold circuit using resonant-tunneling diodes (RTDs). The logic operation is based on detecting a switching sequence in the RTD circuit. This scheme enables us to increase the number of threshold voltages by more than ... Keywords: Resonant-tunneling diode, Multiple-threshold, analog-to-digital converter
Takao Waho; Kazufumi Hattori; Kouji Honda
Robust algorithm for tunnel closing in 3D volumetric objects based on topological characteristics of points
In this letter, we propose a robust, linear in time modification of Aktouf, Bertrand and Perroton's algorithm for tunnel (3D hole) closing in 3D volumetric objects. Our algorithm is insensitive to small distortions and branches. The algorithm has been ... Keywords: 3D image processing, Crack bridging, Skeletonisation, Topological numbers, Tunnel closing
Marcin Janaszewski; Micha? Postolski; Laurent Babout
Low-Speed Wind-Tunnel Investigation of the Stability and Control Characteristics
A wind-tunnel investigation was conducted in the Langley 12-Foot Low-Speed Tunnel to study the low-speed stability and control characteristics of a series of four flying wings over an extended range of angle of attack (-8\\deg to 48\\deg). Because of the ...
Fears Scott P.; Ross Holly M.; Moul Thomas M.
Large-Eddy Simulation: How Large is Large Enough?
The length scale evolution of various quantities in a clear convective boundary layer (CBL), a stratocumulus-topped boundary layer, and three radiatively cooled (�smoke cloud�) convective boundary layers are studied by means of large-eddy ...
Stephan R. de Roode; Peter G. Duynkerke; Harm J. J. Jonker
Petrology and geochemistry of samples from bed-contact zones in Tunnel Bed 5, U12g-Tunnel, Nevada Test Site
This report summarizes the detailed geologic characterization of samples of bed-contact zones and surrounding nonwelded bedded tuffs, both within Tunnel Bed 5, that are exposed in the G-Tunnel complex beneath Rainier Mesa on the Nevada Test Site (NTS). Original planning studies treated the bed-contact zones in Tunnel Bed 5 as simple planar surfaces of relatively high permeability. Detailed characterization, however, indicates that these zones have a finite thickness, are depositional in origin, vary considerably over short vertical and horizontal distances, and are internally complex. Fluid flow in a sequence of nonwelded zeolitized ash-flow or bedded tuffs and thin intervening reworked zones appears to be a porous-medium phenomenon, regardless of the presence of layering. There are no consistent differences in either bulk composition or detailed mineralogy between bedded tuffs and bed-contact zones in Tunnel Bed 5. Although the original bulk composition of Tunnel Bed 5 was probably peralkaline, extensive zeolitization has resulted in a present peraluminous bulk composition of both bedded tuffs and bed-contact zones. The major zeolite present, clinoptilolite, is intermediate (Ca:K:Na = 26:35:39) and effectively uniform in composition. This composition is similar to that of clinoptilolite from the tuffaceous beds of Calico Hills above the static water level in hole USW G-1, but somewhat different from that reported for zeolites from below the static water level in USW G-2. Tunnel Bed 5 also contains abundant hydrous manganese oxides. The similarity in composition of the clinoptilolites from Tunnel Bed 5 and those above the static water level at Yucca Mountain indicates that many of the results of nuclide-migration experiments in Tunnel Bed 5 would be transferrable to zeolitized nonwelded tuffs above the static water level at Yucca Mountain.
Connolly, J.R.; Keil, K.; Mansker, W.L.; Allen, C.C.; Husler, J.; Lowy, R.; Fortney, D.R.; Lappin, A.R.
Facility Closure Report for Tunnel U16a, Area 16, Nevada Test Site, Nevada
U16a is not listed in the Federal Facility Agreement and Consent Order. The closure of U16a was sponsored by the Defense Threat Reduction Agency (DTRA) and performed with the cooperation of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office and the Nevada Division of Environmental Protection. This report documents closure of this site as identified in the DTRA Fiscal Year 2008 Statement of Work, Task 6.3. Closure activities included: � Removing and disposing of a shack and its contents � Disposing of debris from within the shack and in the vicinity of the tunnel entrance � Verifying that the tunnel is empty � Welding screened covers over tunnel vent holes to limit access and allow ventilation � Constructing a full-tunnel cross-section fibercrete bulkhead to prevent access to the tunnel Field activities were conducted from July to August 2008.
Combined Experiment Phase 1. [Horizontal axis wind turbines: wind tunnel testing versus field testing
How does wind tunnel airfoil data differ from the airfoil performance on an operating horizontal axis wind turbine (HAWT) The National Renewable Energy laboratory has been conducting a comprehensive test program focused on answering this question and understanding the basic fluid mechanics of rotating HAWT stall aerodynamics. The basic approach was to instrument a wind rotor, using an airfoil that was well documented by wind tunnel tests, and measure operating pressure distributions on the rotating blade. Based an the integrated values of the pressure data, airfoil performance coefficients were obtained, and comparisons were made between the rotating data and the wind tunnel data. Care was taken to the aerodynamic and geometric differences between the rotating and the wind tunnel models. This is the first of two reports describing the Combined Experiment Program and its results. This Phase I report covers background information such as test setup and instrumentation. It also includes wind tunnel test results and roughness testing.
Butterfield, C.P.; Musial, W.P.; Simms, D.A.
Topeka's "Green Light Tunnel" Saves Fuel and Time | Department of
Topeka's "Green Light Tunnel" Saves Fuel and Time Topeka's "Green Light Tunnel" Saves Fuel and Time Topeka's "Green Light Tunnel" Saves Fuel and Time April 22, 2011 - 1:50pm Addthis Topeka, Kansas, has activated the first of three key traffic corridors to receive a "green light tunnel," a real-time adaptive traffic signal system that synchronizes signals to create a series of green lights for motorists. The result is fewer stops, less travel time and -- most importantly -- a lot of saved gasoline. Sallie Glaize Project Officer, Office of Energy Efficiency & Renewable Energy What does this project do? Saves motorists in Topeka time and money. The first of three key traffic corridors in Topeka, Kansas has received a "green light tunnel," a real-time adaptive traffic signal system that
The Influence of Strain Relaxation on the Electrical Properties of Submicron Si/SiGe Resonant-Tunneling Diodes
Resonant tunneling devices (RTDs) and resonant tunneling transistors (RTTs) are possible building blocks with increased functionality of future microelectronic circuits. These quantum devices can be made in the Si/SiGe system, which is compatible with ... Keywords: SiGe, resonant tunneling, strain relaxation
P. W. Lukey; J. Caro; T. Zijlstra; E. van der Drift; S. Radelaar
Properties of tunnel junctions with fluorocarbon dielectric barriers
Thesis. The electrical characteristics of In/I/In and In/I/Pb superconducting tunnel junctions have been studied in detail. Since In does not readily form pinhole free oxide layers, a thin insulating dielectric was formed on freshly deposited In film by passing an electric discharge through an atmosphere of fluorocarbon gas. Junctions were then completed by depositing a thin counter electrode of In or Pb. The same process was used to prepare high resistance junctions with Au as the base electrode; these were not however, studied in detail. In/I/In and In/I/Pb junctions were produced with resistances in the range 0.01 ohms to 10/sup 10/ ohms at liquid helium temperatures. Low resistance junctions exhibited nonlinear electrical characteristics associated with good quality oxide'' superconducting junctions including (a) the dc Josephson effcct, (b) quasiparticle tunneling characteristics. (c) phonon structure and (d) inelastic tunneling phenomena. The magnitude of the Josephson current for In/I/In junctions agreed to within a few percent of the value predicted by strong coupling theory. Current voltage (I-V) and first and second derivative curves for In/I/In and In/I/Pb were compared with curves for Al/I/In and Pb/I/Pb junctions. Discrepancies between the characteristics can be, for the most part, explained on the basis of existing theories of phonon mediated superconductivity using recent data from inelastic neutron scattering studies of In. Nonlinear structure at voltages below the phonon spectrum was observed and is most likely associated with Kohn singularities. At higher voltages, second derivative curves exhibited resonances characteristic of CH and OH impurities in the barrier as well as a complex spectrum associated with the vibrational spectrum of the fluorocarbon dielectric. To better characterize this dielectric, a variety of surface analytic techniques were used to determine the complex index of refraction, the chemical composition and chemical homogeneity of the barrier. I-V curves for high resistance junctions were used to determine the potential at the metal-insulator interface. (auth)
Jack, M.D.
Survey of radon and radon daughter concentrations in selected Rainier Mesa tunnels
A survey of radon and radon daughter concentrations (RDCs) in selected tunnels on Rainier Mesa at the Nevada Test Site (NTS) was conducted as a part of the underground testing program at NTS. Measurements were taken in three tunnels, N, T, and G. Results of preliminary measurements indicate that N and T Tunnels have low RDCs, i.e., 0.01 WL (working level) (3% of the EPA standard), with normal ventilation conditions. However, it was demonstrated that RDCs can rise to relatively high levels, i.e., 0.24 WL when ventilation rates are significantly lowered. The radon daughter concentrations measured in G Tunnel were an order of magnitude higher than those in N and T Tunnels. The average RDC in the rock mechanics drift (the ''worst-case'' location in G Tunnel) was 0.13 WL with a range from 0.07 WL to 0.23 WL. Elevated RDCs found in the rock mechanics drift of G Tunnel seemed to be attributable to a lower ventilation rate in conjunction with the more highly fractured nature of the ''welded tuff'' rock formation in which the incline drift was mined. By increasing the ventilation rate, a 60% reduction in RDCs from an average of 0.13 Wl to an average of 0.05 WL was achieved.
Fauver, D.N.
Axial Ge/Si nanowire heterostructure tunnel FETs
The vapor-liquid-solid (VLS) growth of semiconductor nanowires allows doping and composition modulation along their axis and the realization of axial 1 D heterostructures. This provides additional flexibility in energy band-edge engineering along the transport direction which is difficult to attain by planar materials growth and processing techniques. We report here on the design, growth, fabrication, and characterization of asymmetric heterostructure tunnel field-effect transistors (HTFETs) based on 100% compositionally modulated Si/Ge axial NWs for high on-current operation and low ambipolar transport behavior. We discuss the optimization of band-offsets and Schottky barrier heights for high performance HTFETs and issues surrounding their experimental realization. Our HTFET devices with 10 nm PECVD SiN{sub x} gate dielectric resulted in a measured current drive exceeding 100 {mu}A/{mu}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios.
Picraux, Sanuel T [Los Alamos National Laboratory; Daych, Shadi A [Los Alamos National Laboratory
A millikelvin scanning tunneling microscope with two independent scanning systems
We describe the design, construction and operation of a scanning tunneling microscope (STM) with two tips that can independently acquire simultaneous scans of a sample. The STM is mounted on a dilution refrigerator and the setup includes vibration isolation, rf-filtered wiring, an ultra high vacuum (UHV) sample preparation chamber and sample transfer mechanism. We present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 $\\mu$eV. Atomic resolution topographic images of an Au(100) surface taken with the inner and outer tips were found to have root mean square roughness of 1.75 $\\pm$ 0.01 pm and 3.55 $\\pm$ 0.03 pm respectively.
Roychowdhury, A; Anderson, J R; Lobb, C J; Wellstood, F C; Dreyer, M
Development of Ta-based Superconducting Tunnel Junction X-ray Detectors for Fluorescence XAS
We are developing superconducting tunnel junction (STJ) soft X-ray detectors for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS). Our 36-pixel Nb-based STJ spectrometer covers a solid angle {Omega}/4{pi} {approx} 10{sup -3}, offers an energy resolution of {approx}10-20 eV FWHM for energies up to {approx}1 keV, and can be operated at total count rates of {approx}10{sup 6} counts/s. For increased quantum efficiency and cleaner response function, we have now started the development of Ta-based STJ detector arrays. Initial devices modeled after our Nb-based STJs have an energy resolution below 10 eV FWHM for X-ray energies below 1 keV, and pulse rise time discrimination can be used to improve their response function for energies up to several keV. We discuss the performance of the Ta-STJs and outline steps towards the next-generation of large STJ detector arrays with higher sensitivity.
Friedrich, S; Drury, O; Hall, J; Cantor, R
Dynamical tunneling in molecules: role of the classical resonances and chaos
In this letter we study dynamical tunneling in highly excited symmetric molecules. The role of classical phase space structures like resonances and chaos on the tunneling splittings are illustrated using the water molecule as an example. It is argued that the enhancements in the splittings due to resonances (near-integrable phase space) and due to chaos (mixed phase space) are best understood away from the fluctuations associated with avoided crossings. In particular we provide an essential difference between the two mechanisms in terms of high order perturbation theory. The analysis, apart from testing the validity of a perturbative approach, suggests such systems as prime candidates for studying dynamical tunneling.
Srihari Keshavamurthy
ScanningTunneling Luminescence of Grain Boundaries in Cu(In,Ga)Se2
At the Laboratory, photon emission in semiconductors has been mapped in the nanoscale using scanning tunneling microscopy (STM). In this Solar Program Review Meeting, we report on the latest results obtained in Cu(In,Ga)Se2 (CIGS) thin films by this adapted STM. Scanning tunneling luminescence (STL) spectroscopy suggests that photons are emitted near the surface of CIGS. STL is excited either by (1) diffusion of tunneling electrons and subsequent recombination with available holes in CIGS or (2) impact ionization by hot electrons. Which process becomes predominant depends on the voltage applied to the STM tip. Photon mapping shows electronically active, extended defects near the surface of CIGS thin films.
Romero, M. J.; Jiang, C.-S.; Al-Jassim, M. M.; Noufi, R.
Ultrathin Co/Pt and Co/Pd superlattice films for MgO-based perpendicular magnetic tunnel junctions
Ultrathin [Co/Pt]{sub n} and [Co/Pd]{sub n} superlattice films consisting of 0.14-0.20-nm-thick Co and Pt(Pd) layers were deposited by sputtering. A large perpendicular magnetic anisotropy [(3-9)x10{sup 6} ergs/cm{sup 3}] and an ideal square out-of-plane hysteresis loop were attained even for ultrathin superlattice films with a total thickness of 1.2-2.4 nm. The films were stable against annealing up to 370 deg. C. MgO-based perpendicular magnetic tunnel junctions with this superlattice layer as the free layer showed a relatively high magnetoresistance ratio (62%) and an ultralow resistance-area product (3.9 {Omega} {mu}m{sup 2}) at room temperature. The use of these films will enable the development of gigabit-scale nonvolatile memory.
Yakushiji, K.; Saruya, T.; Kubota, H.; Fukushima, A.; Nagahama, T.; Yuasa, S.; Ando, K. [Spintronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)
Large displacement spherical joint
A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.
Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)
Riming of Graupel: Wind Tunnel Investigations of Collection Kernels and Growth Regimes
Laboratory experiments were carried out in the vertical wind tunnel in Mainz, Germany, to study the collision coalescence growth of single spherical ice particles having initial radii between 290 and 380 ?m while they were freely floated in a ...
Nadine von Blohn; Karoline Diehl; Subir K. Mitra; Stephan Borrmann
Wind Tunnel Tests of Parabolic Trough Solar Collectors: March 2001--August 2003
Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.
Hosoya, N.; Peterka, J. A.; Gee, R. C.; Kearney, D.
Atomic-Scale Chemical Imaging via Combination of Scanning Tunneling and Electron Energy Loss Spectroscopies
Atomic-Scale Chemical Imaging via Combination of Scanning Tunneling and Electron Energy Loss visualization of chemical reaction pathways to provide mechanistic understanding for catalytically important systems at atomic level Develop atomically resolved chemical imaging platform via combination of low
Turbulence Spectra and Dissipation Rates in a Wind Tunnel Model of the Atmospheric Convective Boundary Layer
A model of the atmospheric convective boundary layer (CBL) is realized in the thermally stratified wind tunnel of the Institute of Hydrology and Water Resources, University of Karlsruhe. Further experimental results from this model are presented. ...
Rolf Kaiser; Evgeni Fedorovich
Sponginess and Drop Shedding of Gyrating Hailstones in a Pressure-Controlled Icing Wind Tunnel
Artificial hailstones were grown in an icing wind tunnel under simulated natural conditions, starting from oblate ice spheroids with major and minor diameters of 2.0 and 1.3 cm respectively, while undergoing symmetric gyration. The experiments ...
G. B. Lesins; Roland List
Simulation study of an ultra thin body silicon on insulator tunnel field effect transistor
This paper presents a modified UTB SOI TFET structure and a thorough simulation study of various device design parameters on this structure. Keywords: UTB-SOI-TFET, band-to-band tunneling, sub-threshold swing
Partha Sarathi Gupta; Sayan Kanungo; Hafizur Rahaman; Partha Sarathi Dasgupta
Double Barrier Resonant Tunneling Transistor with a Fully Two Dimensional Emitter
A novel planar resonant tunneling transistor is demonstrated. The growth structure is similar to that of a double-barrier resonant tunneling diode (RTD), except for a fully two-dimensional (2D) emitter formed by a quantum well. Current is fed laterally into the emitter, and the 2D--2D resonant tunneling current is controlled by a surface gate. This unique device structure achieves figures-of-merit, i.e. peak current densities and peak voltages, approaching that of state-of-the-art RTDs. Most importantly, sensitive control of the peak current and voltage is achieved by gating of the emitter quantum well subband energy. This quantum tunneling transistor shows exceptional promise for ultra-high speed and multifunctional operation at room temperature.
Earth pressure balance (EPB) tunneling induced settlements in the Tren Urbano Project, Rio Piedras, Puerto Rico
Underground construction of the Rio Piedras section of the Tren Urbano project involved the construction of twin tunnels (6.3m diameter) with Earth Pressure Balance machines in weathered alluvial soil. The depth of the ...
Abrams, Alejandro J
Analyses of coupled hydrological-mechanical effects during drilling of the FEBEX tunnel at Grimsel
fluid pressure responses observed during TBM drilling of thefluid- pressure responses observed in the rock mass during TBM drillingdrilling, the open boundary at the tunnel wall controls the fluid
Rutqvist, J.; Rejeb, A.; Tijani, M.; Tsang, C.-F.
Fire modeling for Building 221-T - T Plant Canyon Deck and Railroad Tunnel
This report was prepared by Hughes Associates, Inc. to document the results of fire models for building 221-T Canyon Deck and Railroad Tunnel. Backup data is contained in document No. WHC-SD-CP-ANAL-010, Rev. 0.
Oar, D.L.
Investigation of the tunneling emitter bipolar transistor as spin-injector into silicon
In this thesis is discussed the tunneling emitter bipolar transistor as a possible spin-injector into silicon. The transistor has a metallic emitter which as a spin-injector will be a ferromagnet. Spin-polarized electrons ...
Van Veenhuizen, Marc Julien
Quantum-limited detection of millimeter waves using superconducting tunnel junctions
The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit by studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 {plus_minus} 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker`s theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.
Mears, C.A.
The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit by studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 {plus minus} 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.
Conductance fluctuations in chaotic systems with tunnel barriers
Quantum effects are expected to disappear in the short-wavelength, semiclassical limit. As a matter of fact, recent investigations of transport through quantum chaotic systems have demonstrated the exponential suppression of the weak localization corrections to the conductance and of the Fano factor for shot-noise when the Ehrenfest time exceeds the electronic dwell time. On the other hand, conductance fluctuations, an effect of quantum coherence, retain their universal value in the limit of the ratio of Ehrenfest time over dwell time to infinity, when the system is ideally coupled to external leads. Motivated by this intriguing result we investigate conductance fluctuations through quantum chaotic cavities coupled to external leads via (tunnel) barriers of arbitrary transparency. Using the trajectory-based semiclassical theory of transport, we find a linear Ehrenfest time-dependence of the conductance variance showing a nonmonotonous, sinusoidal behavior as a function of the transperancy. Most notably, we find an increase of the conductance fluctuations with the Ehrenfest time, above their universal value, for the transparency less than 0.5. These results, confirmed by numerical simulations, show that, contrarily to the common wisdom, effects of quantum coherence may increase in the semiclassical limit, under special circumstances.
Daniel Waltner; Jack Kuipers; Philippe Jacquod; Klaus Richter
Ultra-low voltage resonant tunnelling diode electroabsorption modulator
Embedding a double barrier resonant tunnelling diode (RTD) in an unipolar InGaAlAs optical waveguide gives rise to a very low driving voltage electroabsorption modulator (EAM) at optical wavelengths around 1550 nm. The presence of the RTD within the waveguide core introduces high non-linearity and negative differential resistance in the current-voltage (I-V) characteristic of the waveguide. This makes the electric field distribution across the waveguide core strongly dependent on the bias voltage: when the current decreases from the peak to the valley there is an increase of the electric field across the depleted core. The electric field enhancement in the core-depleted layer causes the Franz-Keldysh absorption band-edge to red shift, which is responsible for the electroabsorption effect. High frequency ac signals as low as 100 mV can induce electric field high speed switching, producing substantial light modulation (up to 15 dB) at photon energies slightly lower than the waveguide core band-gap energy. The k...
Figueiredo, J M L; Stanley, C R
Property:Wind Capabilities | Open Energy Information
Capabilities Capabilities Jump to: navigation, search Property Name Wind Capabilities Property Type String Pages using the property "Wind Capabilities" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + None + 10-ft Wave Flume Facility + None + 11-ft Wave Flume Facility + Yes + 2 2-ft Flume Facility + None + 3 3-ft Wave Flume Facility + None + 5 5-ft Wave Flume Facility + None + 6 6-ft Wave Flume Facility + None + A Alden Large Flume + Yes + Alden Small Flume + Yes + Alden Tow Tank + Yes + Alden Wave Basin + Yes + B Breakwater Research Facility + None + Bucknell Hydraulic Flume + None + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + None + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + None +
Property:Towing Capabilities | Open Energy Information
Towing Capabilities Towing Capabilities Jump to: navigation, search Property Name Towing Capabilities Property Type String Pages using the property "Towing Capabilities" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + None + 10-ft Wave Flume Facility + None + 11-ft Wave Flume Facility + None + 2 2-ft Flume Facility + None + 3 3-ft Wave Flume Facility + None + 5 5-ft Wave Flume Facility + None + 6 6-ft Wave Flume Facility + None + A Alden Large Flume + Yes + Alden Small Flume + None + Alden Tow Tank + Yes + Alden Wave Basin + None + B Breakwater Research Facility + None + Bucknell Hydraulic Flume + Yes + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + None + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + None +
Property:Test Services | Open Energy Information
Services Services Jump to: navigation, search Property Name Test Services Property Type String Pages using the property "Test Services" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + Yes + 10-ft Wave Flume Facility + Yes + 11-ft Wave Flume Facility + Yes + 2 2-ft Flume Facility + Yes + 3 3-ft Wave Flume Facility + Yes + 5 5-ft Wave Flume Facility + Yes + 6 6-ft Wave Flume Facility + Yes + A Alden Large Flume + Yes + Alden Small Flume + Yes + Alden Tow Tank + Yes + Alden Wave Basin + Yes + B Breakwater Research Facility + None + Bucknell Hydraulic Flume + Yes + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + None + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + None + Carderock Circulating Water Channel + None +
Property:Special Characteristics | Open Energy Information
Characteristics Characteristics Jump to: navigation, search Property Name Special Characteristics Property Type String Pages using the property "Special Characteristics" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + None + 10-ft Wave Flume Facility + None + 11-ft Wave Flume Facility + Yes + 2 2-ft Flume Facility + None + 3 3-ft Wave Flume Facility + None + 5 5-ft Wave Flume Facility + None + 6 6-ft Wave Flume Facility + Yes + A Alden Large Flume + Yes + Alden Small Flume + Yes + Alden Tow Tank + None + Alden Wave Basin + Yes + B Breakwater Research Facility + None + Bucknell Hydraulic Flume + Yes + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + None + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + None +
Property:Cameras | Open Energy Information
Property Property Edit with form History Facebook icon Twitter icon » Property:Cameras Jump to: navigation, search Property Name Cameras Property Type Text Pages using the property "Cameras" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + None 10-ft Wave Flume Facility + None 11-ft Wave Flume Facility + None 2 2-ft Flume Facility + None 3 3-ft Wave Flume Facility + None 5 5-ft Wave Flume Facility + None 6 6-ft Wave Flume Facility + None A Alden Large Flume + Yes Alden Small Flume + Yes Alden Tow Tank + Yes Alden Wave Basin + Yes B Breakwater Research Facility + None C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + None Carderock 3-ft Variable Pressure Cavitation Water Tunnel + None Carderock Circulating Water Channel + None
Property:Wavemaking Capabilities | Open Energy Information
Wavemaking Capabilities Wavemaking Capabilities Jump to: navigation, search Property Name Wavemaking Capabilities Property Type String Pages using the property "Wavemaking Capabilities" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + Yes + 10-ft Wave Flume Facility + Yes + 11-ft Wave Flume Facility + Yes + 2 2-ft Flume Facility + Yes + 3 3-ft Wave Flume Facility + Yes + 5 5-ft Wave Flume Facility + Yes + 6 6-ft Wave Flume Facility + Yes + A Alden Large Flume + Yes + Alden Small Flume + Yes + Alden Tow Tank + None + Alden Wave Basin + Yes + B Breakwater Research Facility + Yes + Bucknell Hydraulic Flume + None + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + None + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + None +
Property:Real-Time | Open Energy Information
Real-Time Real-Time Jump to: navigation, search Property Name Real-Time Property Type String Pages using the property "Real-Time" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + No + 10-ft Wave Flume Facility + No + 11-ft Wave Flume Facility + No + 2 2-ft Flume Facility + No + 3 3-ft Wave Flume Facility + No + 5 5-ft Wave Flume Facility + No + 6 6-ft Wave Flume Facility + No + A Alden Large Flume + Yes + Alden Small Flume + Yes + Alden Tow Tank + Yes + Alden Wave Basin + Yes + B Breakwater Research Facility + No + Bucknell Hydraulic Flume + No + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + No + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + No + Carderock Circulating Water Channel + No +
Category:Testing Facilities | Open Energy Information
Facilities Facilities Jump to: navigation, search This category is defined by the form Testing Facility. Subcategories This category has only the following subcategory. H [×] Hydrodynamic Testing Facility Type 9 pages Pages in category "Testing Facilities" The following 82 pages are in this category, out of 82 total. 1 1.5-ft Wave Flume Facility 10-ft Wave Flume Facility 11-ft Wave Flume Facility 2 2-ft Flume Facility 3 3-ft Wave Flume Facility 5 5-ft Wave Flume Facility 6 6-ft Wave Flume Facility A Alden Large Flume Alden Small Flume Alden Tow Tank Alden Wave Basin B Breakwater Research Facility Bucknell Hydraulic Flume C Carderock 2-ft Variable Pressure Cavitation Water Tunnel Carderock 3-ft Variable Pressure Cavitation Water Tunnel Carderock Circulating Water Channel
Developing a CD-CBM Anticipatory Approach for Cavitation - Defining a Model-Based Descriptor Consistent Across Processes, Phase 1 Final Report Context-Dependent Prognostics and Health Assessment: A New Paradigm for Condition-based Maintenance SBIR Topic No. N98-114
The objective of this research, and subsequent testing, was to identify specific features of cavitation that could be used as a model-based descriptor in a context-dependent condition-based maintenance (CD-CBM) anticipatory prognostic and health assessment model. This descriptor is based on the physics of the phenomena, capturing the salient features of the process dynamics. The test methodology and approach were developed to make the cavitation features the dominant effect in the process and collected signatures. This would allow the accurate characterization of the salient cavitation features at different operational states. By developing such an abstraction, these attributes can be used as a general diagnostic for a system or any of its components. In this study, the particular focus will be pumps. As many as 90% of pump failures are catastrophic. They seem to be operating normally and fail abruptly without warning. This is true whether the failure is sudden hardware damage requiring repair, such as a gasket failure, or a transition into an undesired operating mode, such as cavitation. This means that conventional diagnostic methods fail to predict 90% of incipient failures and that in addressing this problem, model-based methods can add value where it is actually needed.
Meet with Large Businesses
Meet with Large Businesses Meet with Large Businesses and learn about upcoming acquisitions! * Federal Energy Management Program (FEMP) * National Renewable Energy Laboratory (NREL) * Small Business Administration (SBA) * U.S. Department of Energy / Energy, Efficiency, and Renewable Energy (EERE) * U.S. Department of Energy / Golden Field Office (GFO) * Western Area Power Administration (WAPA) * Colorado Procurement Technical Assistance Center (PTAC)
Investigation of an Asymmetric B Factory in the PEP Tunnel
for the lower voltage requirement. The general caveatrequirement for large-angle crab cavities, with their unwanted impedances and their possibly difficult voltage
Chattapadhyay, A.
Some investigations on the enhancement of boiling heat transfer from planer surface embedded with continuous open tunnels
Boiling heat transfer from a flat surface can be enhanced if continuous open tunnel type structures are embedded in it. Further, improvement of boiling heat transfer from such surfaces has been tried by two separate avenues. At first, inclined tunnels are embedded over the solid surface and an effort is made to optimize the tunnel inclination for boiling heat transfer. Surfaces are manufactured in house with four different inclinations of the tunnels with or without a reentrant circular pocket at the end of the tunnel. Experiments conducted in the nucleate boiling regime showed that 45 deg inclination of the tunnels for both with and without base geometry provides the highest heat transfer coefficient. Next, active fluid rotation was imposed to enhance the heat transfer from tunnel type surfaces with and without the base geometry. Rotational speed imparted by mechanical stirrer was varied over a wide range. It was observed that fluid rotation enhances the heat transfer coefficient only up to a certain value of stirrer speed. Rotational speed values, beyond this limit, reduce the boiling heat transfer severely. A comparison shows that embedding continuous tunnel turns out to be a better option for the increase of heat transfer coefficient compared to the imposition of fluid rotation. But the behavior of inclined tunnels under the action of fluid rotation is yet to be established and can be treated as a future scope of the work. (author)
Das, A.K.; Das, P.K.; Saha, P. [Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721 302 (India)
Cryogenic studies for the proposed CERN large hadron electron collider (LHEC)
The LHeC (Large Hadron electron Collider) is a proposed future colliding beam facility for lepton-nucleon scattering particle physics at CERN. A new 60 GeV electron accelerator will be added to the existing 27 km circumference 7 TeV LHC for collisions of electrons with protons and heavy ions. Two basic design options are being pursued. The first is a circular accelerator housed in the existing LHC tunnel which is referred to as the "Ring-Ring" version. Low field normal conducting magnets guide the particle beam while superconducting (SC) RF cavities cooled to 2 K are installed at two opposite locations at the LHC tunnel to accelerate the beams. For this version in addition a 10 GeV re-circulating SC injector will be installed. In total four refrigerators with cooling capacities between 1.2 kW and 3 kW @ 4.5 K are needed. The second option
Final Report on LDRD Project: Development of Quantum Tunneling Transistors for Practical Circuit Applications
The goal of this LDRD was to engineer further improvements in a novel electron tunneling device, the double electron layer tunneling transistor (DELTT). The DELTT is a three terminal quantum device, which does not require lateral depletion or lateral confinement, but rather is entirely planar in configuration. The DELTT's operation is based on 2D-2D tunneling between two parallel 2D electron layers in a semiconductor double quantum well heterostructure. The only critical dimensions reside in the growth direction, thus taking full advantage of the single atomic layer resolution of existing semiconductor growth techniques such as molecular beam epitaxy. Despite these advances, the original DELTT design suffered from a number of performance short comings that would need to be overcome for practical applications. These included (i)a peak voltage too low ({approx}20 mV) to interface with conventional electronics and to be robust against environmental noise, (ii) a low peak current density, (iii) a relatively weak dependence of the peak voltage on applied gate voltage, and (iv) an operating temperature that, while fairly high, remained below room temperature. In this LDRD we designed and demonstrated an advanced resonant tunneling transistor that incorporates structural elements both of the DELTT and of conventional double barrier resonant tunneling diodes (RTDs). Specifically, the device is similar to the DELTT in that it is based on 2D-2D tunneling and is controlled by a surface gate, yet is also similar to the RTD in that it has a double barrier structure and a third collector region. Indeed, the device may be thought of either as an RTD with a gate-controlled, fully 2D emitter, or alternatively, as a ''3-layer DELTT,'' the name we have chosen for the device. This new resonant tunneling transistor retains the original DELTT advantages of a planar geometry and sharp 2D-2D tunneling characteristics, yet also overcomes the performance shortcomings of the original DELTT design. In particular, it exhibits the high peak voltages and current densities associated with conventional RTDs, allows sensitive control of the peak voltage by the control gate, and operates nearly at room temperature. Finally, we note under this LDRD we also investigated the use of three layer DELTT structures as long wavelength (Terahertz) detectors using photon-assisted tunneling. We have recently observed a narrowband (resonant) tunable photoresponse in related structures consisting of grating-gated double quantum wells, and report on that work here as well.
Large-Scale Hydropower
Energy.gov (U.S. Department of Energy (DOE))
Large-scale hydropower plants are generally developed to produce electricity for government or electric utility projects. These plants are more than 30 MW in size, and there is more than 80,000 MW...
Large Eddy Simulation of Wind Loads on a Low-Rise ...
... Dynamics (CFD), referred as virtual wind tunnel ... Tunnel Laboratory of the University of Western ... dynamic Smagorinsky-Lilly model does implement a ...
Wind Tunnel Aeroacoustic Tests of Six Airfoils for Use on Small Wind Turbines: Preprint
Aeroacoustic tests of seven airfoils were performed in an open jet anechoic wind tunnel. Six of the airfoils are candidates for use on small wind turbines operating at low Reynolds number. One airfoil was tested for comparison to benchmark data. Tests were conducted with and without boundary layer tripping. In some cases a turbulence grid was placed upstream in the test section to investigate inflow turbulence noise. An array of 48 microphones was used to locate noise sources and separate airfoil noise from extraneous tunnel noise. Trailing edge noise was dominant for all airfoils in clean tunnel flow. With the boundary layer untripped, several airfoils exhibited pure tones that disappeared after proper tripping was applied. In the presence of inflow turbulence, leading edge noise was dominant for all airfoils.
Migliore, P.; Oerlemans, S.
Intermediate-band photosensitive device with quantum dots having tunneling barrier embedded in organic matrix
A plurality of quantum dots each have a shell. The quantum dots are embedded in an organic matrix. At least the quantum dots and the organic matrix are photoconductive semiconductors. The shell of each quantum dot is arranged as a tunneling barrier to require a charge carrier (an electron or a hole) at a base of the tunneling barrier in the organic matrix to perform quantum mechanical tunneling to reach the respective quantum dot. A first quantum state in each quantum dot is between a lowest unoccupied molecular orbital (LUMO) and a highest occupied molecular orbital (HOMO) of the organic matrix. Wave functions of the first quantum state of the plurality of quantum dots may overlap to form an intermediate band.
Forrest, Stephen R. (Ann Arbor, MI)
Measurement of the Equivalent Thermal Resistance of Rooftop Lawns in a Hot-Climate Wind Tunnel
In a very hot summer equivalent to a Guangzhou summer, the reduction of heat coming into rooms is very important with respect to thermal comfort and energy efficiency. The objective of this study is to investigate the evaporation cooling effect on a rooftop lawn. A hot-climate wind tunnel experiment was carried out in order to obtain and analyze the heat and moisture transport in the rooftop lawn. Furthermore, a calculation with the energy conservation equation was carried out using the results of the hot-climate wind tunnel experiment. The calculated equivalent thermal resistance and synthesis exterior surface heat transfer coefficient were in fairly good agreement with that in the design standard for energy efficiency of residential buildings in the hot summer and warm winter zone, while the average velocity in hot-climate wind tunnel equals the summer average outdoor velocity in Guangzhou.
Meng, Q.; Zhang, Y.; Zhang, L.
e+ e- collider in the VLHC tunnel. Proceedings, Workshop, Chicago, USA, March 9-11, 2001
This document is a collection of the contributions made to the March IIT workshop on an e{sup +}e{sup -} collider in the VLHC tunnel. This machine, which is based on a relatively conservative extrapolation of LEP technology, has a baseline luminosity of 10{sup 33}/cm{sup 2}/s at a CM energy of 370 GeV. The overall parameters and general description of such a machine is described in T. Sen and J. Norem, ''A Very Large Lepton Collider in the VLHC Tunnel'', to be published. A preprint of this paper is included as Appendix 2 of this report. The intention of the workshop was to define the parameters of such a collider and make them available to the community for use in further physics studies. It is clear that the machine cannot compete with a full scale linear collider. Its main interest would be if a VLHC were built and if a linear collider did not already exist. In this case, it could provide a limited and perhaps crucial view of low mass Higgs states. Although the study is incomplete, it does define rather well the parameters of the machine, as well as the challenges that the design faces. The study benefited greatly from the participation of the machine experts that were willing to spend time looking at the design. In this document, the workshop contributions are organized into sections which cover the physics motivation for the machine; the injector; beam dynamics issues in the collider; and accelerator systems. The physics section describes luminosity benchmarks for study of a light Higgs boson, and machine performance issues related to lineshape measurements at the t{bar t} threshold. The contribution on the injector presents a design for a 45 GeV injector. The injection energy is motivated by two considerations: the collider has potential stability problems at injection, which are mitigated by a relatively high injection energy; and, at this energy, the injector can also serve as a Z{sup 0} factory. One of the principal conclusions of the IIT workshop was that this was the most natural way to provide a high-luminosity Z{sup 0} factory with polarized beams. The beam dynamics contributions cover a range of topics, including experience from LEP, design options for the lattice and IR's that aim at increasing the luminosity to close to 10{sup 34}/cm{sup 2}/s, and considerations on beam stability, rf system distribution, beam separation, and radiative spin polarization of the beams. The magnet, vacuum system, and rf system required for the machine are discussed in the accelerator systems contributions. Finally, in the conclusions section, the leading R&D issues for the machine, as identified at the workshop, are summarized. In an Appendix, some thoughts on beam-beam considerations for a VLLC are provided.
Dugan, D., (ed.); /Cornell U., LEPP; Tollestrup, A., (ed.); /Fermilab
A Wind Tunnel Investigation of the Effect of an External, Vertical Electric Field on the Shape of Electrically Uncharged Rain Drops
Results are presented of a recent wind tunnel experiment in which electrically unchanged water drops of 1000�3000 ?m equivalent radius were freely suspended in the vertical air stream of the UCLA Cloud Tunnel. During their suspension, the drops ...
R. Rasmussen; C. Walcek; H.R. Pruppacher; S.K. Mitra; J. Lew; V. Levizzani; P.K. Wang; U. Barth
Characteristics of wind power on Savonius rotor using a guide-box tunnel
This study investigates to improve and adjust the output power of Savonius rotor under various wind power and suggests the method of prevention the rotor from strong wind disaster. In this study, as the appropriate device to achieve the purpose of it, a guide-box tunnel is employed. The guide-box tunnel is like a rectangular box as wind passage in which a test rotor is included. The area ratio between the inlet and exit of it is variable to adjust the inlet mass flow rate or input power. At first, the experiment was conducted to find the adequate configuration which would provide the best relative performance. The present experiment, however, does not include the test to retain the guide-box tunnel from the strong wind. The experiments include the static torque test of the fixed rotor at any phase angle and the dynamic torque test at rotation of them. Consequently, it was found that the maximum rotor rotational speed was achieved in the range of the guide-box area ratio between 0.3 and 0.7 and the value of the output power coefficient of the rotor with guide-box tunnel of the area ratio 0.43 increases about 1.5 times with three blades and 1.23 times with two blades greater than that without guide-box tunnel, respectively. It seemed that the performance of Savonius rotor within the guide-box tunnel is comparable enough with other methods for augmentation and control of the output. (author)
Irabu, Kunio; Roy, Jitendro Nath [Faculty of Mechanical Engineering, University of the Ryukyus, Senbaru-1, Nishihara, Okinawa 903-0213 (Japan)
Regulation of the intersubunit ammonia tunnel in Mycobacterium tuberculosis glutamine-dependent NAD[superscript +] synthetase
Glutamine-dependent NAD{sup +} synthetase is an essential enzyme and a validated drug target in Mycobacterium tuberculosis (mtuNadE). It catalyses the ATP-dependent formation of NAD{sup +} from NaAD{sup +} (nicotinic acid-adenine dinucleotide) at the synthetase active site and glutamine hydrolysis at the glutaminase active site. An ammonia tunnel 40 {angstrom} (1 {angstrom} = 0.1 nm) long allows transfer of ammonia from one active site to the other. The enzyme displays stringent kinetic synergism; however, its regulatory mechanism is unclear. In the present paper, we report the structures of the inactive glutaminase C176A variant in an apo form and in three synthetase-ligand complexes with substrates (NaAD{sup +}/ATP), substrate analogue {l_brace}NaAD{sup +}/AMP-CPP (adenosine 5'-[{alpha},{beta}-methylene]triphosphate){r_brace} and intermediate analogues (NaAD{sup +}/AMP/PPi), as well as the structure of wild-type mtuNadE in a product complex (NAD{sup +}/AMP/PPi/glutamate). This series of structures provides snapshots of the ammonia tunnel during the catalytic cycle supported also by kinetics and mutagenesis studies. Three major constriction sites are observed in the tunnel: (i) at the entrance near the glutaminase active site; (ii) in the middle of the tunnel; and (iii) at the end near the synthetase active site. Variation in the number and radius of the tunnel constrictions is apparent in the crystal structures and is related to ligand binding at the synthetase domain. These results provide new insight into the regulation of ammonia transport in the intermolecular tunnel of mtuNadE.
Chuenchor, Watchalee; Doukov, Tzanko I.; Resto, Melissa; Chang, Andrew; Gerratana, Barbara (SSRL); (Maryland)
Effects of diesel exhaust on the microbiota within a tuffaceous tunnel system
The abundance and distribution of microbiota that may be impacted by diesel and diesel exhaust were investigated from three depths into the walls and invert (floor) of U12n tunnel at Rainier Mesa, Nevada Test Site, a potential geological analog of Yucca Mountain. Enumerations included total cell counts, and numbers of aerobic heterotrophic, sulfate-reducing, nitrate-reducing, and diesel-degrading bacteria. Additionally, the disappearance of total petroleum hydrocarbons was determined in microcosms containing subsurface materials that were amended with diesel fuel. Results revealed that microbes capable of utilizing diesel and diesel combustion products were present in the subsurface in both the walls and the invert of the tunnel. The abundance of specific bacterial types in the tunnel invert, a perturbed environment, was greater than that observed in the tunnel wall. Few trends of microbial distribution either into the tunnel wall or the invert were noted with the exception of aerobic heterotrophic abundance which increased with depth into the wall and decreased with depth into the invert. No correlation between microbiota and a specific introduced chemical species have yet been determined. The potential for microbial contamination of the tunnel wall during sampling was determined to be negligible by the use of fluorescently labeled latex spheres (1{mu}m in dia.) as tracers. Results indicate that additional investigations might be needed to examine the microbiota and their possible impacts on the geology and geochemistry of the subsurface, both indigenous microbiota and those microorganisms that will likely be introduced by anthropogenic activity associated with the construction of a high-level waste repository.
Haldeman, D.L.; Lagadinos, T.; Amy, P.S. [Univ. of Nevada, Las Vegas, NV (United States); Hersman, L. [Los Alamos National Lab., NM (United States); Meike, A. [Lawrence Livermore National Lab., Livermore, CA (United States)
Estimation of gate-to-channel tunneling current in ultra-thin oxide sub-50nm double gate devices
Double gate (DG) FETs have emerged as the most promising technology for sub-50nm transistor design. However, analysis and control of the gate tunneling leakage in DGFET is necessary to fully exploit their advantages. In this paper we have modeled (numerically ... Keywords: Direct tunneling, Double gate, Leakage, Quantum confinement
Saibal Mukhopadhyay; Keunwoo Kim; Jae-Joon Kim; Shih-Hsien Lo; Rajiv V. Joshi; Ching-Te Chuang; Kaushik Roy
Using tevatron magnets for HE-LHC or new ring in LHC tunnel
Two injector accelerator options for HE-LHC of p{sup +} - p{sup +} collisions at 33 TeV cms energy are briefly outlined. One option is based on the Super-SPS (S-SPS) accelerator in the SPS tunnel, and the other one is based on the LER (Low-Energy-Ring) accelerator in the LHC tunnel. Expectations of performance of the main arc accelerator magnets considered for the construction of the S-SPS and of the LER accelerators are used to tentatively devise some selected properties of these accelerators as potential injectors to HE-LHC.
Piekarz, Henryk; /Fermilab
Attachments for fire modeling for Building 221-T, T Plant canyon deck and railroad tunnel
The purpose of this attachment is to provide historical information and documentation for Document No. WHC-SD-CP-ANAL-008 Rev 0, ``Fire Modeling for Building 221-T--T Plant Canyon Deck and Railroad Tunnel``, dated September 29, 1994. This data compilation contains the following: Resumes of the Technical Director, Senior Engineer and Junior Engineer; Review and Comment Record; Software Files; CFAST Input and Output Files; Calculation Control Sheets; and Estimating Sprinkler Actuation Time in the Canyon and Railroad Tunnel. The T Plant was originally a fuel reprocessing facility. It was modified later to decontaminate and repair PuRex process equipment.
Oar, D.L. [Westinghouse Hanford Co., Richland, WA (United States)
Bose-Hubbard dimer scattered from a potential barrier: from co-tunneling to dissociation
We consider a Bose-Hubbard dimer scattered from a potential barrier. A numerical approach has been developed to treat the stationary scattering problem. It allows to compute the tunneling and dissociation probabilities for arbitrary shape of the potential barrier and arbitrary kinetic energy of the dimer. The obtained results are shown to be in agreement with previous studies of the dimer wave-packet dynamics [A.R.Kolovsky, J.Link, and S.Wimberger, New J. of Phys. {\\bf 14}, 075002 (2012)]. In particular, we reproduce the effect of resonant tunneling found in the cited paper and show that this effect can be enhanced by decreasing the dimer kinetic energy.
Dmitrii N. Maksimov; Andrey R. Kolovsky
Thin-film metal coated insulation barrier in a Josephson tunnel junction. [Patent application
A highly stable, durable, and reproducible Josephson tunnel junction consists of a thin-film electrode of a hard superconductor, a thin oxide insulation layer over the electrode constituting a Josephson tunnel junction barrier, a thin-film layer of stabilizing metal over the barrier, and a second thin-film hard superconductive electrode over the stabilizing film. The thin stabilizing metal film is made only thick enough to limit penetration of the electrode material through the insulation layer so as to prevent a superconductive short.
Hawkins, G.A.; Clarke, J.
Monolithic interconnected module with a tunnel junction for enhanced electrical and optical performance
An improved thermophotovoltaic (TPV) n/p/n device is provided. Monolithic Interconnected Modules (MIMS), semiconductor devices converting infrared radiation to electricity, have been developed with improved electrical and optical performance. The structure is an n-type emitter on a p-type base with an n-type lateral conduction layer. The incorporation of a tunnel junction and the reduction in the amount of p-type material used results in negligible parasitic absorption, decreased series resistance, increased voltage and increased active area. The novel use of a tunnel junction results in the potential for a TPV device with efficiency greater than 24%.
Murray, Christopher S. (Bethel Park, PA); Wilt, David M. (Bay Village, OH)
A Monolithic Interconnected module with a tunnel Junction for Enhanced Electrical and Optical Performance
An improved thermophotovoltaic (TPV) n/p/n device is provided. Monolithic Interconnected Modules (MIMs), semiconductor devices converting infrared radiation to electricity, have been developed with improved electrical and optical performance. The structure is an n-type emitter on a p-type base with an n-type lateral conduction layer. The incorporation of a tunnel junction and the reduction in the amount of p-type material used results in negligible parasitic absorption, decreased series resistance, increased voltage and increased active area. The novel use of a tunnel junction results in the potential for a TPV device with efficiency greater than 24%.
Murray, Christopher Sean; Wilt, David Morgan
Effects of boron composition on tunneling magnetoresistance ratio and microstructure of CoFeB/MgO/CoFeB pseudo-spin-valve magnetic tunnel junctions
The effect of B concentration on the tunneling magnetoresistance (TMR) of (Co{sub 25}Fe{sub 75}){sub 100-x}B{sub x}/MgO/(Co{sub 25}Fe{sub 75}){sub 100-x}B{sub x} (x = 22 and 33) pseudo-spin-valve (P-SV) magnetic tunnel junctions (MTJs) was investigated. The TMR ratios for optimally annealed MTJs with x = 22 and 33 were 340% and 170%, respectively, at room temperature. High resolution transmission electron microscopy (HRTEM) observation showed a weaker (001) texture in the MgO barrier in the MTJ with x = 33. The bottom electrode was not fully crystallized even with a considerable amount of B in the (Co{sub 25}Fe{sub 75}){sub 67}B{sub 33}, while good epitaxy was observed between (001) textured MgO and (Co{sub 25}Fe{sub 75}){sub 78}B{sub 22} electrodes.
Kodzuka, M. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-0047 (Japan); Ohkubo, T. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Hono, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-0047 (Japan); National Institute for Materials Science, Tsukuba 305-0047 (Japan); Ikeda, S.; Ohno, H. [Center for Spintronics Integrated Systems, Tohoku University, Sendai 980-8577 (Japan); Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Gan, H. D. [Center for Spintronics Integrated Systems, Tohoku University, Sendai 980-8577 (Japan)
Giant tunneling magnetoresistance up to 330% at room temperature in sputter deposited Co{sub 2}FeAl/MgO/CoFe magnetic tunnel junctions
Magnetoresistance ratio up to 330% at room temperature (700% at 10 K) has been obtained in a spin-valve-type magnetic tunnel junction (MTJ) consisting of a full-Heusler alloy Co{sub 2}FeAl electrode and a MgO tunnel barrier fabricated on a single crystal MgO (001) substrate by sputtering method. The output voltage of the MTJ at one-half of the zero-bias value was found to be as high as 425 mV, which is the largest reported to date in MTJs using Heusler alloy electrodes. The present finding suggests that Co{sub 2}FeAl may be one of the most promising candidates for future spintronics devices applications.
Wang Wenhong; Sukegawa, Hiroaki; Shan, Rong; Mitani, Seiji; Inomata, Koichiro [Magnetic Materials Center, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047 (Japan)
Understanding Tunneling Magnetoresistance During Thermal Annealing in MgO-based Junctions with CoFeB Electrodes
The competition between the interface crystallization and diffusion processes, their influence on the onset of symmetry-filtering coherent tunneling of {Delta}{sub 1} band electrons in the MgO-based magnetic tunnel junctions is investigated. Systematic study of the transport and magnetoresistance during thermal annealing of these junctions shows a unique behavior of the tunneling conductance in the parallel state. The optimal annealing time for achieving giant tunneling magnetoresistance at different temperatures is determined. The evolution of magnetoresistance consists of three distinct regions, responsible by different contributions from CoFeB electrodes and the MgO barrier. The whole phenomenon can be understood through an empirical model based on the Landauer tunneling picture.
Wang, W.; Ni, C; Miao, X; Weiland, C; Shah, L; Fan, X; Parson, P; Jordan-Sweet, J; Kou, X; Zhang, Y
Wind tunnel simulation of wind effects and associated displacement hazards on flat surface construction materials such as plywood
Accidents and hazards continue to plague the construction industry. One often overlooked hazard to workers is the potential for flying debris and materials during high winds. This research was designed to evaluate the wind velocity required to create such an airborne hazard with flat surface materials such as plywood. This research was developed to show select correlations between the wind velocity, lifting forces and the susceptibility to movement of large surface area flat sheets of construction material, specifically four feet by eight feet sheets of floordeck plywood weighing 107 pounds. It also examined and evaluated the correlation of a shape coefficient to movement of materials and wind velocities, so that calculations can be made to adequately predict the potential movement of these materials. This will allow construction supervisors to reasonably prepare for such anticipated conditions. The Texas A&M University low speed wind tunnel was used to place a ftffl-scale stack of plywood floor decking material with the air stream flowing over the stack until top sheet separated or lifted from the stack. Next, a half-scale model was placed in the test section of the tunnel with pressure ports attached to a high speed sampling transducer to measure the actual pressures at select velocities. This allowed for a correlation between the ftifl-scale data and the sampled data. Tests were performed for several front and side angles of the wind striking the edge surface of the materials. Velocities were used up to 60 miles per hour full-scale equivalent. The full-scale model achieved lift forces exceeding the material weight of 107 pounds at one orientation angle at a velocity just below 30 miles per hour. This was consistent with the half-scale test pressures for a similar orientation. Various orientations yielded different forces as was anticipated. From this information a pressure coefficient was developed which when applied with a safety factor allows for reasonable calculations to be made to determine potential hazards and adequately secure materials on any sites where large flat materials may be handled or stored.
Madeley, Jack T.
Large Occlusion Stereo
A method for solving the stereo matching problem in the presence of large occlusion is presented. A data structure�the disparity space image�is defined to facilitate the description of the effects of occlusion on the stereo matching process ... Keywords: disparity-space, dynamic-programming stereo, occlusion, stereo
Aaron F. Bobick; Stephen S. Intille
Composting Large Animal Carcasses
Disposing of large animal carcasses can be a problem for agricultural producers. Composting is a simple, low-cost method that yields a useful product that can be used as fertilizer. In this publication you'll learn the basics of composting, how to build and maintain a compost pile, tools you will need, and how to use the finished compost.
Auvermann, Brent W.; Mukhtar, Saqib; Heflin, Kevin
Electron tunneling in MIS capacitors with the MBE-grown fluoride layers on Si(111) and Ge(111): Role of transverse momentum conservation
The current-voltage characteristics of the metal-insulator-semiconductor tunneling structures with calcium fluoride are simulated using different theoretical models. The results are compared to the data of current measurements on the fabricated capacitors ... Keywords: Calcium fluoride, MIS capacitors, Transverse momentum conservation, Tunnel emitter phototransistor, Tunneling current
Y. Y. Illarionov; M. I. Vexler; S. M. Suturin; V. V. Fedorov; N. S. Sokolov; K. Tsutsui; K. Takahashi
Cavitation Erosion of Francis Turbines
About this Abstract. Meeting, Materials Science & Technology 2013. Symposium, Advances in Hydroelectric Turbine Manufacturing and Repair. Presentation�...
Implicit Large Eddy Simulation
National Nuclear Security Administration (NNSA)
Implicit Implicit Large Eddy Simulation (ILES) for High Reynolds Number Flows Len Margolin Applied Physics Division Los Alamos National Laboratory Collaborators: 1. Bill Rider (LANL) 2. Piotr Smolarkiewicz (NCAR) 3. Andrzej Wysogrodski (NCAR) 4. Fernando Grinstein (NRL) email@example.com 1 Implicit Large Eddy Simulation Outline: * What is ILES? * What are its advantages? * Historical perspective * Why does it work? * Some examples firstname.lastname@example.com 2 What is ILES ILES is the direct application of a fluid solver to a high Reynolds number fluid flow with no explicit turbulence model. · The truncation terms of the algorithm serve as an effective model of the effects of the unresolved scales. · Fluid solvers based on Nonoscillatory Finite Volume (NFV) approximations work effectively for ILES. · Fluid solvers based on pseudospectral methods, leapfrog methods, advective form methods, etc. do not work
Density-gradient theory: a macroscopic approach to quantum confinement and tunneling in semiconductor devices
Density-gradient theory provides a macroscopic approach to modeling quantum transport that is particularly well adapted to semiconductor device analysis and engineering. After some introductory observations, the basis of the theory in macroscopic and ... Keywords: Continuum, Density-gradient, Electron transport, Quantum confinement, Quantum tunneling, Semiconductor device simulation, Thermodynamics
M. G. Ancona
Wind Tunnel Experiment for Predicting a Visible Plume Region from a Nuclear Power Plant Cooling Tower
The current paper introduces a wind tunnel experiment to study the effect of the cooling tower of a Nuclear Power Plant (NPP) on the flow and the characteristics of visible plume regions. The relevant characteristics of the flow field near the ...
Guo Dong-peng; Yao Ren-tai; Fan Dan
Mobile Sensor Routing for Parameter Estimation of Distributed Systems Using the Parallel Tunneling Method
The paper deals with the problem of optimal path planning for a sensor network with mutliple mobile nodes, whose measurements are supposed to be primarily used to estimate unknown parameters of a system modelled by a partial differential equation. The ... Keywords: Distributed Parameter Systems, Optimum Experimental Design, Parallel Computing, Sensor Network, Tunneling Algorithm
Tomasz Zi?ba; Dariusz Uci?ski
A Wind Tunnel Investigation on the Riming of Snowflakes. Part II: Natural and Synthetic Aggregates
Natural and artificial snowflakes have been rimed both in free fall and while suspended on a thin flexible fiber in the UCLA cloud tunnel. The results of these experiments show that during the early stage of riming, the motions exhibited by a ...
A Simple Technique for Simultaneous Suspension of Multiple Drops in a Small Vertical Wind Tunnel
A simple technique is described by which multiple millimeter-size water drops can be simultaneously suspended in an air stream above the test section of a 12 � 12 cm cross section of a vertical wind tunnel. Horizontal profiles of the vertical air ...
A. K. Kamra; D. V. Ahire
Tunneling vs. thermionic currents in multi-quantum well photovoltaic structures
Photogeneration in the intrinsic region of a p-i-n device excites carriers in the conduction bands with non-zero currents. A special class of multi-quantum well photovoltaic structures (mqw-PV) is p-i-n PV structures where photo-generation may cause ... Keywords: microelectronics, quantum wells, solar cells, superlattices, tunneling
Argyrios C. Varonides; Robert A. Spalletta
Charged fermion tunnelling from electrically and magnetically charged rotating black hole in de Sitter space
Thermal radiation of electrically charged fermions from rotating black hole with electric and magnetic charges in de Sitter space is considered. The tunnelling probabilities for outgoing and incoming particles are obtained and the Hawking temperature is calculated. The relation for the classical action for the particles in the black hole's background is also found.
M. M. Stetsko
The black-hole area spectrum in the tunneling formalism with GUP
The black hole area spectrum has been studied in the framework of tunneling mechanism, where a Generalized Uncertainty Principle (GUP) has been considered. The results implies in a non evenly spaced spectrum for the black hole area which becomes increasingly spaced as the black hole evaporates.
Silva, C A S
C. A. S. Silva; R. R. Landim
Fast recovery from dual-link or single-node failures in IP networks using tunneling
This paper develops novel mechanisms for recovering from failures in IP networks with proactive backup path calculations and Internet Protocol (IP) tunneling. The primary scheme provides resilience for up to two link failures along a path. The highlight ... Keywords: IP fast reroute, failure recovery, independent trees, multiple-link failure, network protection, node failure
Shrinivasa Kini; Srinivasan Ramasubramanian; Amund Kvalbein; Audun Fosselie Hansen
of a building was explored [2]. Referred to such applications, a VAWT can be so small in physical size that its by the present authors to study the aerodynamic performance of small VAWTs using the experimental and numerical1 WIND-TUNNEL STUDY ON AERODYNAMIC PERFORMANCE OF SMALL VERTICAL-AXIS WIND TURBINES J. J. Miau*1
Leu, Tzong-Shyng "Jeremy"
Unsteady Aerodynamics Experiment Phase VI: Wind Tunnel Test Configurations and Available Data Campaigns
The primary objective of the insteady aerodynamics experiment was to provide information needed to quantify the full-scale, three-dimensional aerodynamic behavior of horizontal-axis wind turbines. This report is intended to familiarize the user with the entire scope of the wind tunnel test and to support the use of the resulting data.
Hand, M. M.; Simms, D. A.; Fingersh, L. J.; Jager, D. W.; Cotrell, J. R.; Schreck, S.; Larwood, S. M.
Investigating the IPv6 teredo tunnelling capability and performance of internet clients
The Teredo auto-tunnelling protocol allows IPv6 hosts behind IPv4 NATs to communicate with other IPv6 hosts. It is enabled by default on Windows Vista and Windows 7. But Windows clients are self-constrained: if their only IPv6 access is Teredo, they ... Keywords: ipv6, teredo
Sebastian Zander; Lachlan L.H. Andrew; Grenville Armitage; Geoff Huston; George Michaelson
Role of Coulomb blockade and spin-flip scattering in tunneling magnetoresistance of FeCo-Si-O nanogranular films
In this work, we report the effect of FeCo atomic fraction (0.33 < x < 0.54) and temperature on the electrical, magnetic, and tunneling magnetoresistance (TMR) properties of FeCo-Si-O granular films prepared by atom beam sputtering technique. Glancing angle x-ray diffraction and TEM studies reveal that films are amorphous in nature. The dipole-dipole interactions (particle-matrix mixing) is evident from zero-field cooled and field-cooled magnetic susceptibility measurements and the presence of oxides (mainly Fe-related) is observed by x-ray photoelectron spectroscopy analysis. The presence of Fe-oxides is responsible for the observed reduction of saturation magnetization and rapid increase in coercivity below 50 K. TMR has been observed in a wide temperature range, and a maximum TMR of -4.25% at 300 K is observed for x = 0.39 at a maximum applied field of 60 kOe. The fast decay of maximum TMR at high temperatures and lower TMR values at 300 K when compared to P{sub FeCo}{sup 2}/(1+P{sub FeCo}{sup 2}), where P{sub FeCo} is the spin polarization of FeCo are in accordance with a theoretical model that includes spin-flip scattering processes. The temperature dependent study of TMR effect reveals a remarkably enhanced TMR at low temperatures. The TMR value varies from -2.1% at 300 K to -14.5% at 5 K for x = 0.54 and a large MR value of -18.5% at 5 K for x = 0.39 is explained on the basis of theoretical models involving Coulomb blockade effects. Qualitatively particle-matrix mixing and the presence of Fe-oxides seems to be the source of spin-flip scattering, responsible for fast decay of TMR at high temperatures. A combination of higher order tunneling (in Coulomb blockade regime) and spin-flip scattering (high temperature regime) explains the temperature dependent TMR of these films.
Kumar, Hardeep; Ghosh, Santanu [Nanostech Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Buerger, Danilo; Zhou, Shengqiang; Groetzschel, Rainer; Schmidt, Heidemarie [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); Li, Lin [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100 871 (China); Kabiraj, Debdulal; Avasthi, Devesh Kumar [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)
Wind Tunnel Study of Turbulent Flow Structure in the Convective Boundary Layer Capped by a Temperature Inversion
Experiments on simulating the atmospheric convective boundary layer (CBL), capped by a temperature inversion and affected by surface shear, were carried out in the thermally stratified wind tunnel of the Institute of Hydrology and Water Resources,...
Evgeni Fedorovich; Rolf Kaiser; Matthias Rau; Erich Plate
Modeling of Plume Downwash and Enhanced Diffusion near Buildings: Comparison to Wind Tunnel Observations for in Arctic Industrial Site
The ability of a modified Industrial Source Complex model to simulate concentration distributions resulting from high wind speeds (neutral conditions) has been evaluated by comparison to data from a wind tunnel study of a Prudhoe Bay, AK oil-...
Alex Guenther; Brian Lamb; Ronald Petersen
Alongwind Dispersion�A Simple Similarity Formula Compared with Observations at 11 Field Sites and in One Wind Tunnel
Observations of alongwind dispersion of clouds were collected from 11 field sites and from one wind tunnel and were used to test simple similarity relations. Because most of the observations consist of concentration time series from fixed ...
Steven R. Hanna; Pasquale Franzese
Nitric Acid Oxidized ZrO$_2$ as the Tunneling Oxide of Cobalt Silicide Nanocrystal Memory Devices
In this study, ZrO$_2$ formed by the nitric acid oxidation method is proposed to be the tunneling oxide for nonvolatile memory device applications. The sputtered Zr thin film was oxidized ...
Chih-Wei Hu; Ting-Chang Chang; Chun-Hao Tu; Yang-Dong Chen; Chao-Cheng Lin; Min-Chen Chen; Jian-Yang Lin; Simon M. Sze; Tseung-Yuen Tseng
Earth pressure balance (EPB) shield tunneling in Bangkok : ground response and prediction of surface settlements using artificial neural networks
Although Earth Pressure Balance (EPB) shields have been used for several decades, very little information exists about the actual mechanisms of shield-ground interaction. The ground response mechanism induced by EPB tunneling ...
Suwansawat, Suchatvee, 1972-
A Historical Evaluation of the U12t Tunnel, Nevada Test Site, Nye County, Nevada, Volume 1 of 6
This report presents a historical evaluation of the U12t Tunnel on the Nevada Test Site in southern Nevada. The work was conducted by the Desert Research Institute at the request of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office and the U.S. Department of Defense, Defense Threat Reduction Agency (DTRA). The U12t Tunnel is one of a series of tunnels used for underground nuclear weapons effects tests on the east side of Rainier and Aqueduct Mesas. Six nuclear weapons effects tests, Mint Leaf, Diamond Sculls, Husky Pup, Midas Myth/Milagro, Mighty Oak, and Mission Ghost, and one high explosive test, SPLAT, were conducted within the U12t Tunnel from 1970 to 1987. All six of the nuclear weapons effects tests and the high explosive test were sponsored by DTRA. Two conventional weapons experiments, Dipole Knight and Divine Eagle, were conducted in the tunnel portal area in 1997 and 1998. These experiments were sponsored by the Defense Special Weapons Agency. The U12t Tunnel complex is composed of the Portal and Mesa Areas and includes an underground tunnel with a main access drift and nine primary drifts, a substantial tailings pile fronting the tunnel portal, a series of discharge ponds downslope of the tailings pile, and two instrumentation trailer parks and 16 drill holes on top of Aqueduct Mesa. A total of 89 cultural features were recorded: 54 at the portal and 35 on the mesa. In the Portal Area, cultural features are mostly concrete pads and building foundations; other features include the portal, rail lines, the camel back, ventilation and cooling system components, communication equipment, and electrical equipment. On the mesa are drill holes, a few concrete pads, a loading ramp, and electrical equipment.
Harold Drollinger; Robert C. Jones; and Thomas F. Bullard; Desert Research Institute, Laurence J. Ashbaugh, Southern Nevada Courier Service and Wayne R. Griffin, Stoller-Navarro Joint Venture
A Historical Evaluation of the U12t Tunnel, Nevada Test Site, Nye County, Nevada, Volume 6 of 6
A Historical Evaluation of the U12t Tunnel, Nevada Test Site, Nye County, Nevada, Volume 3 of 6
A Historical Evaluation of the U12t Tunnel, Nevada Test Site, Nye County, Nevada, Volume 5 of 6
Modeling of Damage, Permeability Changes and Pressure Responses during Excavation of the TSX Tunnel in Granitic Rock at URL, Canada
This paper presents numerical modeling of excavation-induced damage, permeability changes, and fluid-pressure responses during excavation of the TSX tunnel at the underground research laboratory (URL) in Canada. Four different numerical models were applied, using a wide range of approaches to model damage and permeability changes in the excavation disturbed zone (EDZ) around the tunnel. Using in situ calibration of model parameters the modeling could reproduce observed spatial distribution of damage and permeability changes around the tunnel, as a combination of disturbance induced by stress redistribution around the tunnel and by the drill-and-blast operation. The modeling showed that stress-induced permeability increase above the tunnel is a result of micro and macrofracturing under high deviatoric (shear) stress, whereas permeability increases alongside the tunnel as a result of opening of existing microfractures under decreased mean stress. The remaining observed fracturing and permeability changes around the periphery of the tunnel were attributed to damage from the drill-and-blast operation. Moreover, a reasonably good agreement was achieved between simulated and observed excavation-induced pressure responses around the TSX tunnel for 1 year following its excavation. The simulations showed that these pressure responses are caused by poroelastic effects as a result of increasing or decreasing mean stress, with corresponding contraction or expansion of the pore volume. The simulation results for pressure evolution were consistent with previous studies, indicating that the observed pressure responses could be captured in a Biot model using a relatively low Biot-Willis coefficient, {alpha} {approx} 0.2, a porosity of n {approx} 0.007, and a relatively low permeability of k {approx} 2 x 10{sup -22} m{sup 2}, which is consistent with the very tight, unfractured granite at the site.
Rutqvist, Jonny; Borgesson, Lennart; Chijimatsu, Masakazu; Hernelind, Jan; Jing, Lanru; Kobayashi, Akira; Nguyen, Son
A Historical Evaluation of the U12t Tunnel, Nevada Test Site, Nye County, Nevada, Volume 2 of 6
A Historical Evaluation of the U12t Tunnel, Nevada Test Site, Nye County, Nevada, Volume 4 of 6
The Control System for the Cryogenics in the LHC Tunnel
The Large Hadron Collider makes extensive use of superconductors, in magnets for bending and focusing the particles, and in RF cavities for accelerating them, which are operated at 1.9 K and 4.5 K. The process automation for the cryogenic distribution around the accelerator circumference is based on 16 Programmable Logic Controllers, each running 250 control loops, 500 alarms and interlocks, and a phase sequencer. Spread along 27 km and under ionizing radiation, 15 000 cryogenic sensors and actuators are accessed through industrial field networks. We describe the main hardware and software components of the control system, their deployment and commissioning, together with the project organization, challenges faced, and solutions found.
Gomes, P; Antoniotti, F; Avramidou, R; Balle, Ch; Blanco-Vi�uela, E; Carminati, Ch; Casas-Cubillos, J; Ciechanowski, M; Dragoneas, A; Dubert, P; Fampris, X; Fluder, C; Fortescue, E; Gaj, W; Gousiou, E; Jeanmonod, N; Jod?owski, P; Karagiannis, F; Klisch, M; L�pez, A; Macuda, P; Malinowski, P; Molina, E; Paiva, S; Patsouli, A; Penacoba, G; Sosin, M; Soubiran, M; Suraci, A; Tovar, A; Vauthier, N; Wolak, T; Zwalinski, L
Hanford waste tanks - light at the end of the tunnel
The U.S. Department of Energy (DOE) faced several problems in its Hanford Site tank farms in the early nineties. It had 177 waste tanks, ranging in size from 55,000 to 1,100,000 gallons, which contained more than 55 million gallons of liquid and solid high-level radioactive waste (HLW) from a variety of processes. Unfortunately, waste transfer records were incomplete. Chemical reactions going on in the tanks were not totally understood. Every tank had high concentrations of powerful oxidizers in the form of nitrates and nitrites, and some tanks had relatively high concentrations of potential fuels that could react explosively with oxidizers. A few of these tanks periodically released large quantities of hydrogen and nitrous oxide, a mixture that was potentially more explosive than hydrogen and air. Both the nitrate/fuel and hydrogen/nitrous oxide reactions had the potential to rupture a tank exposing workers and the general public to unacceptably large quantities of radioactive material. One tank (241-C-106) was generating so much heat that water had to be added regularly to avoid thermal damage to the tank's concrete exterior shell. The tanks contained more than 250 million Curies of radioactivity. Some of that radioactivity was in the form of fissile plutonium, which represented a potential criticality problem. As awareness of the potential hazards grew, the public and various regulatory agencies brought increasing pressure on DOE to quantify the hazards and mitigate any that were found to be outside accepted risk guidelines. In 1990, then Representative, now Senator Ron Wyden (D-Oregon), introduced an amendment to Public Law 101-510, Section 3137, that required DOE to identify Hanford tanks that might have a serious potential for release of high-level waste.
Large forging manufacturing process
A process for forging large components of Alloy 718 material so that the components do not exhibit abnormal grain growth includes the steps of: a) providing a billet with an average grain size between ASTM 0 and ASTM 3; b) heating the billet to a temperature of between 1750.degree. F. and 1800.degree. F.; c) upsetting the billet to obtain a component part with a minimum strain of 0.125 in at least selected areas of the part; d) reheating the component part to a temperature between 1750.degree. F. and 1800.degree. F.; e) upsetting the component part to a final configuration such that said selected areas receive no strains between 0.01 and 0.125; f) solution treating the component part at a temperature of between 1725.degree. F. and 1750.degree. F.; and g) aging the component part over predetermined times at different temperatures. A modified process achieves abnormal grain growth in selected areas of a component where desirable.
Thamboo, Samuel V. (Latham, NY); Yang, Ling (Niskayuna, NY)
Spectroscopy and capacitance measurements of tunneling resonances in an Sb-implanted point contact.
We fabricated a split-gate defined point contact in a double gate enhancement mode Si-MOS device, and implanted Sb donor atoms using a self-aligned process. E-beam lithography in combination with a timed implant gives us excellent control over the placement of dopant atoms, and acts as a stepping stone to focused ion beam implantation of single donors. Our approach allows us considerable latitude in experimental design in-situ. We have identified two resonance conditions in the point contact conductance as a function of split gate voltage. Using tunneling spectroscopy, we probed their electronic structure as a function of temperature and magnetic field. We also determine the capacitive coupling between the resonant feature and several gates. Comparison between experimental values and extensive quasi-classical simulations constrain the location and energy of the resonant level. We discuss our results and how they may apply to resonant tunneling through a single donor.
Wendt, Joel Robert; Rahman, Rajib; Ten Eyck, Gregory A.; Eng, Kevin; Carroll, Malcolm S.; Young, Ralph Watson; Lilly, Michael Patrick; Stalford, Harold Lenn; Bishop, Nathaniel; Bielejec, Edward Salvador
Evaluation of barrier uniformity in magnetic tunnel junctions prepared using natural oxidation of thin Mg layers
We fabricated submicron magnetic tunnel junctions (MTJs) using natural oxidation of thin Mg layers deposited by dc sputtering. The MTJs exhibited magnetoresistance (MR) ratios of up to about 150% with a low resistance-area product (R{sub p}A) of 8 {Omega} {mu}m{sup 2}, which are comparable to those for radio-frequency-sputtered MgO barriers. The submicron MTJs had highly variable MR and R{sub p}A values due to a high pinhole density (20 {mu}m{sup -2}) in the barriers, whereas current-in-plane-tunneling (CIPT) measurements on the same MTJ films revealed highly reproducible MR and R{sub p}A values. This indicates that reproducible CIPT measurements do not necessarily give accurate results of MR and R{sub p}A at high pinhole densities.
Seki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Yakushiji, Kay; Yuasa, Shinji; Ando, Koji [National Institute of Advanced Industrial Science Technology (AIST), Spintronics Research Center, Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Maehara, Hiroki; Yamagata, Shinji; Okuyama, Hiroki; Tsunekawa, Koji [Department of Spin Technology Development, Process Development Center, Canon ANELVA Corporation, Kurigi 2-5-1, Asao, Kawasaki, Kanagawa 215-8550 (Japan)
Energy and Effective Mass Dependence of Electron Tunnelling Through Multiple Quantum barriers in Different Heterostructures
Tunneling of electrons through the barriers in heterostructures has been studied, within unified transfer matrix approach. The effect of barrier width on the transmission coefficient of the electrons has been investigated for different pairs of semi conducting materials that are gaining much importance recently. These pairs include CdS/CdSe, AlGaAs/GaAs and InAs/AlSb. Barrier dimensions have been reduced from 20nm to 5nm to observe the effect of scaling on tunneling properties. Material depended is highlighted for electrons with energy varying from below the barrier height to above it. The electron effective mass inside the barrier and the well are often different. The results show that the coupling effect leads to significant changes on the transmission effect. . The effective-mass dependant transmission coefficient has been plotted with respect to electron energy. The computation is based on the transfer matrix method by using MATLAB.
Jatindranath Gain; Madhumita Das Sarkar; Sudakshina Kundu
Atomic-scale properties of semiconductor heterostructures probed by scanning tunneling microscopy
The engineering of advanced semiconductor heterostructure materials and devices requires a detailed understanding of, and control over, the structure and properties of semiconductor materials and devices at the atomic to nanometer scale. Cross-sectional scanning tunneling microscopy has emerged as a unique and powerful method to characterize structural morphology and electronic properties in semiconductor epitaxial layers and device structures at these length scales. The basic experimental techniques in cross-sectional scanning tunneling microscopy are described, and some representative applications to semiconductor heterostructure characterization drawn from recent investigations in the authors laboratory are discussed. Specifically, they describe some recent studies of InP/InAsP and InAsP/InAsSb heterostructures in which nanoscale compositional clustering has been observed and analyzed.
Yu, E.T.; Zuo, S.L.; Bi, W.G.; Tu, C.W. [Univ. of California, San Diego, La Jolla, CA (United States). Dept. of Electrical and Computer Engineering; Biefeld, R.M.; Allerman, A.A. [Sandia National Labs., Albuquerque, NM (United States)
Role of Amorphous Silicon and Tunneling in Heterojunction with Intrinsic Thin Layer (HIT) Solar Cells
This work analyzes heterojunction with intrinsic thin layer (HIT) solar cells using numerical simulations. The differences between the device physics of cells with p- and n-type crystalline silicon (c-Si) wafers are substantial. HIT solar cells with n-type wafers essentially form a n/p/n structure, where tunneling across the junction heterointerfaces is a critical transport mechanism required to attain performance exceeding 20%. For HIT cells with p-type wafers, only tunneling at the back-contact barrier may be important. For p-wafer cells, the hydrogenated amorphous silicon (a-Si:H) between the indium tin oxide (ITO) and crystalline silicon may act as a passivating buffer layer but, otherwise, does not significantly contribute to device performance. For n-wafer cells, the carrier concentration and band alignment of this a-Si:H layer are critical to device performance.
Kanevce, A.; Metzger, W. K.
Effects of elemental distributions on the behavior of MgO-based magnetic tunnel junctions.
Three-dimensional atom-probe tomography and transmission electron microscopy have been utilized to study the effects of Ta getter presputtering and either a Mg or Ru free-layer cap on the elemental distributions and properties of MgO-based magnetic tunnel junctions after annealing. Annealing the samples resulted in crystallization of the amorphous CoFeB layer and diffusion of the majority of the boron away from the crystallized CoFeB layers. The Ta getter presputter is found to reduce the segregation of boron at the MgO/CoFeB interface after annealing, improving the tunneling magnetoresistance of the tunnel junction. This effect is observed for samples with either a Ru free-layer cap or a Mg free-layer cap and is thought to be a result of a reduced oxygen concentration within the MgO due to the effect of Ta getter presputtering. A Ru free-layer cap provides superior magnetic and magnetotransport properties compared to a Mg free-layer cap. Mg from the Mg free-layer cap is observed to diffuse toward the MgO tunnel barrier upon annealing, degrading both the crystalline quality of the CoFeB and magnetic isolation of the CoFeB free-layer from the CoFeB reference-layer. Lateral variations in the B distribution within the CoFeB free-layer are observed in the samples with a Ru free-layer cap, which are associated with crystalline and amorphous grains. The B-rich, amorphous grains are found to be depleted in Fe, while the B-poor crystalline grains are slightly enriched in Fe.
Schreiber, D. K.; Choi, Y. S.; Liu, Y.; Chiaramonti, A. N.; Seidman, D. N.; Petford-Long, A. K. (Center for Nanoscale Materials); ( MSD); (Northwestern Univ.); (Canon-ANELVA Corp.)
Coherent generation of nonclassical light on a chip via photon-induced tunneling and blockade
We report the observation of nonclassical light generated via photon blockade in a photonic crystal cavity with a strongly coupled quantum dot. By tuning the frequency of the probe laser with respect to the cavity and quantum dot resonance we can probe the system in either photon blockade or photon-induced tunneling regime. The transition from one regime to the other is confirmed by the measurement of the second order correlation that changes from anti-bunching to bunching.
Andrei Faraon; Ilya Fushman; Dirk Englund; Nick Stoltz; Pierre Petroff; Jelena Vuckovic
High resolution seismic imaging of Rainier Mesa using surface reflection and surface to tunnel tomography
In the interpretation of seismic data to infer properties of an explosion source, it is necessary to account for wave propagation effects. In order to understand and remove these propagation effects, it is necessary to have a model. An open question concerning this matter is the detail and accuracy which must be present in the velocity model in order to produce reliable estimates in the estimated source properties. While it would appear that the reliability of the results would be directly related to the accuracy of the velocity and density models used in the interpretation, it may be that certain deficiencies in these models can be compensated by the and amount of seismic data which is used in the inversion. The NPE provided an opportunity to test questions of this sort. In August 1993, two high resolution seismic experiments were performed in N-Tunnel and on the surface of Rainier Mesa above it. The first involved a surface-to-tunnel imaging experiment with sources on the surface and receivers in tunnel U12n.23 about 88 meters west of the NPE. It was possible to estimate the apparent average velocity between the tunnel and the surface. In a separate experiment, a high resolution reflection experiment was performed in order to image the lithology in Rainier Mesa. Good quality, broad band, reflections were obtained from depths extending into the Paleozoic basement. A high velocity layer near the surface is underlain by a thick section of low velocity material, providing a nonuniform but low average velocity between the depth of the NPE and the surface.
Majer, E.L.; Johnson, L.R.; Karageorgi, E.K.; Peterson, J.E.
ST/EL and ST/CV services for TI2 & TI8 LHC injection tunnels
This paper describes the ST/EL and ST/CV services for TI2 & TI8 LHC injection tunnels. The cooling and ventilation part describes the requirements for design and installation of more than 10 km of pipeline that is going to be laid down in the tunnels. Main operating parameters as well as manufacture procedures are explained. Preliminary work schedule with the cost estimate is also presented. Electrical power will be distributed from the LHC side and the SPS side for the machine and the general services. All power converters will be installed on surface buildings. The link between the main bend converters and the main bend magnets will be realised with water-cooled cables. Rest of the magnets will be cabled by using conventional copper and aluminium cables. Due to long lengths of the injection tunnels a dry 18kV transformer will be installed in TJ8 to serve the general services for TI8. The same will apply to TI2 by installing a transformer at the bottom of the PMI2 shaft.
Akhtar, S; CERN. Geneva. ST Division
Giromill wind tunnel test and analysis. Volume II. Technical discussion. Final report, June 1976--October 1977
A wind tunnel test of a Giromill rotor was conducted. The objective of this test was to substantiate the performance computed by the Larsen cyclogiro vortex theory. Additional objectives were to obtain performance comparison data between the Giromill, a sinusoidal blade modulation Giromill, a Darrieus rotor, and a modified Darrieus rotor that flips the blades a few degrees. A three bladed Giromill rotor having a diameter of 2.13 m (7 ft) and a span of 1.52 m (5 ft) was tested in the McDonnell Aircraft Company 15 x 20 ft Mini Speed Wind Tunnel. The blade modulations were accomplished through use of a cam and push rod arrangement. Replaceable cams provided the desired blade modulation at the various operating points. Various operating conditions were achieved by adjusting the rotor RPM and tunnel speed. The results show that the Giromill has good performance, equal to or much better than that predicted by theory, and outperforms the other types of vertical axis wind turbines tested.
Moran, W.A.
Wind tunnel test of 1/30 scale heliostat field array model. Test report
From 9 January through 20 January 1978, Honeywell conducted a wind tunnel test on a 1/30 scale partial heliostat field. The heliostats were per Honeywell's design developed under the 10 megawatt central receiver pilot electrical power plant subsystem research experiment contract. Likewise, the scaled section of the field geometry duplicated the proposed circular layout. Testing was conducted at the Georgia Institute of Technology's 9 foot subsonic tunnel. The objective of the test was to ascertain from a qualitative standpoint the field effects upon wind loading within a heliostat field. To accomplish this, numerous pressure tap measurements at different heights and at different field positions were taken with varying wind speeds, fence designs, and heliostat gimbal orientations. The Department of Energy specified boundary layer profile was also scaled by 1/30 in order to simulate the total wind effects as accurately as possible taking into account the potentially severe scaling or Reynolds number effects at a 1/30 scale. After initial model set-up within the tunnel and scaled boundary layer generated, 91 separate runs were accomplished. The results do demonstrate the high sensitivity of wind loading upon the collector field due to the actual heliostat orientation and fence geometry. Vertical pressure gradients within the model field and flow reentry angles provide a good qualitative feel as to the full scale environment that might be expected and point to the need for specific additional testing to further explore potentially dangerous conditions.
Brown, G. L.
Optimal basis set for ab-initio calculations of energy levels in tunneling structures, using the covariance matrix of the wave functions
The paper proposes a method to obtain the optimal basis set for solving the self consistent field (SCF) equations for large atomic systems in order to calculate the energy barriers in tunneling structures, with higher accuracy and speed. Taking into account the stochastic-like nature of the samples of all the involved wave functions for many body problems, a statistical optimization is made by considering the covariance matrix of these samples. An eigenvalues system is obtained and solved for the optimal basis set and by inspecting the rapidly decreasing eigenvalues one may seriously reduce the necessary number of vectors that insures an imposed precision. This leads to a potentially significant improvement in the speed of the SCF calculations and accuracy, as the statistical properties of a large number of wave functions in an large spatial domain may be considered. The eigenvalue problem has to be solved only few times, so that the amount of time added may be much smaller that the overall iterating SCF calculations. A simple implementation of the method is presented for a situation where the analytical solution is known, and the results are encouraging.
Sever Spanulescu
CALIFORNIA ENERGY Large HVAC Building
CALIFORNIA ENERGY COMMISSION Large HVAC Building Survey Information Database of Buildings over 100 Design of Large Commercial HVAC Systems research project, one of six research elements in the Integrated Design of Large Commercial HVAC Systems Integrated Design of Small Commercial HVAC Systems Integrated
Proposal for the award of a contract for dismantling, removal and packaging of the existing Heating, Ventilation and Air-Conditioning (HVAC) systems in the PS tunnel
Giant tunneling magnetoresistance up to 410% at room temperature in fully epitaxial Co/MgO/Co magnetic tunnel junctions with bcc Co(001) electrodes
Fully epitaxial Co(001)/MgO(001)/Co(001) magnetic tunnel junctions (MTJs) with metastable bcc Co(001) electrodes were fabricated with molecular beam epitaxy. The MTJs exhibited giant magnetoresistance (MR) ratios up to 410% at room temperature, the highest value reported to date. Temperature dependence of the MR ratio was observed to be very small compared with fully epitaxial Fe/MgO/Fe and textured CoFeB/MgO/CoFeB MTJs. The MR ratio of the Co/MgO/Co MTJ showed larger bias voltage dependence than that of the epitaxial Fe/MgO/Fe MTJs, which probably reflects the band structures of bcc Co and Fe for the k{sub parallel}=0 direction.
Yuasa, Shinji; Fukushima, Akio; Kubota, Hitoshi; Suzuki, Yoshishige; Ando, Koji [National Institute of Advanced Industrial Science and Technology (AIST), Nanoelectronics Research Institute, Tsukuba, Ibaraki 305-8568 (Japan) and SORST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Nanoelectronics Research Institute, Tsukuba, Ibaraki 305-8568 (Japan)
Taking the 'Large' out of Large Hadron Collider: Computational Breakthrough
Home » News & Publications » News » Science News » Taking the 'Large' out of Large Hadron Collider Taking the 'Large' out of Large Hadron Collider Computational breakthrough hastens modeling of 'tabletop accelerators' August 9, 2010 | Tags: Accelerator Science Contact: Margie Wylie | firstname.lastname@example.com | 510-486-7421 mori1 This 3D simulation shows how laser pulses create plasma wakes that propel electrons forward, much as a surfer is propelled forward by an ocean wave. Laser wakefield acceleration promises electron accelerators that are thousands of times more powerful than, yet a fraction the size of, conventional radio frequency devices. Particle accelerators like the Large Hadron Collider (LHC) at CERN are the big rock stars of high-energy physics-really big. The LHC cost nearly
Methyl quantum tunneling and nitrogen-14 NQR NMR studies using a SQUID magnetic resonance spectrometer
Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) techniques have been very successful in obtaining molecular conformation and dynamics information. Unfortunately, standard NMR and NQR spectrometers are unable to adequately detect resonances below a few megahertz due to the frequency dependent sensitivity of their Faraday coil detectors. For this reason a new spectrometer with a dc SQUID (Superconducting Quantum Interference Device) detector, which has no such frequency dependence, has been developed. Previously, this spectrometer was used to observe {sup 11}B and {sup 27}Al NQR resonances. The scope of this study was increased to include {sup 23}Na, {sup 51}V, and {sup 55}Mn NQR transitions. Also, a technique was presented to observe {sup 14}N NQR resonances through cross relaxation of the nitrogen polarization to adjacent proton spins. When the proton Zeeman splitting matches one nitrogen quadrupoler transition the remaining two {sup 14}N transitions can be detected by sweeping a saturating rf field through resonance. Additionally, simultaneous excitation of two nitrogen resonances provides signal enhancement which helps to connect transitions from the same site. In this way, nitrogen-14 resonances were observed in several amino acids and polypeptides. This spectrometer has also been useful in the direct detection of methyl quantum tunneling splittings at 4.2 K. Tunneling, frequencies of a homologous series of carboxylic acids were measured and for solids with equivalent crystal structures, an exponential correlation between the tunneling frequency and the enthalpy of fusion is observed. This correlation provides information about the contribution of intermolecular interactions to the energy barrier for methyl rotation.
Black, B.E. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States)
The U.S. Department of Energy is evaluating the Baker-Barry Tunnel as a potential GATEWAY Demonstrations project for deployment of solid-state lighting (SSL) technology. The National Park Service views this project as a possible proving ground and template for implementation of light-emitting diode (LED) luminaires in other tunnels, thereby expanding the estimated 40% energy savings from 132 MWh/yr to a much larger figure nationally. Most of the energy savings in this application is attributable to the instant-restrike capability of LED products and to their high tolerance for frequent on/off switching, used here to separately control either end of the tunnel during daytime hours. Some LED luminaires rival or outperform their high-intensity discharge (HID) counterparts in terms of efficacy, but options are limited, and smaller lumen packages preclude true one-for-one equivalence. However, LED products continue to improve in efficacy and affordability at a rate unmatched by other light source technologies; the estimated simple payback period of eight years (excluding installation costs and maintenance savings) can be expected to improve with time. The proposed revisions to the existing high-pressure sodium (HPS) lighting system would require slightly increased controls complexity and significantly increased luminaire types and quantities. In exchange, substantial annual savings (from reduced maintenance and energy use) would be complemented by improved quantity and quality of illumination. Although advanced lighting controls could offer additional savings, it is unclear whether such a system would prove cost-effective; this topic may be explored in future work.
Tunneling dynamics and phase transition of a Bose-Fermi mixture in a double well
The coherent nonlinear tunneling dynamics of a boson-fermion mixture in a double-well potential is studied in this paper. Four types of phase are found for the mixture. The first one is two species localizing in different potential wells. The second one is two species coexisting in the same well. The third one is two species equally populated in two wells. The fourth one is one species equally populated in two wells while the other species is in one well. The phase transitions among these four states have been investigated. The interspecies and intraspecies interactions as well as bosonic and fermionic numbers can dramatically affect these phase transitions.
Qi Pengtang; Duan Wenshan [Department of Physics, Northwest Normal University, Lanzhou, 730070 (China)
Structure and Reactions of Carbon and Hydrogen on Ru(0001): A Scanning Tunneling Microscopy Study
The interaction between carbon and hydrogen atoms on a Ru(0001) surface was studied using scanning tunneling microscopy (STM), Density Functional Theory (DFT) and STM image calculations. Formation of CH species by reaction between adsorbed H and C was observed to occur readily at 100 K. When the coverage of H increased new complexes of the form CH+nH (n = 1, 2 and 3) were observed. These complexes, never observed before, might be precursors for further hydrogenation reactions. DFT analysis reveals that a considerable energy barrier exists for the CH+H {yields} CH{sub 2} reaction.
Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge; Salmeron, Miquel
Tunneling and traversal of ultracold three-level atoms through vacuum-induced potentials
The passage of ultracold three-level atoms through the potential induced by the vacuum cavity mode is discussed using cascade atomic configuration. We study the tunneling or traversal time of the ultracold atoms via a bimodal high-Q cavity. It is found that the phase time, which may be considered as a measure for the time required to traverse the cavity, exhibits superclassical and subclassical behaviors. Further, the dark states and interference effects in cascade atomic configuration may influence the passage time of the atom through the cavity.
Badshah, Fazal; Irfan, Muhammad; Qamar, Shahid [Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan); Qamar, Sajid [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)
Nanometer-scale tunnel formation in metallic glass by helium ion irradiation
We have shown that upon high fluence helium ion irradiation, metallic glass Cu{sub 50}Zr{sub 45}Ti{sub 5} becomes highly porous at the depth of the helium projected range. The resulting porous region is characterized by the formation of a tunnel like structure and self-linkage of nanometer size gas bubbles. Furthermore, the irradiation leads to the formation of nanometer size Cu{sub x}Zr{sub y} crystals that are randomly distributed. The results of this study indicate that the He-filled bubbles have attractive interactions and experience considerable mobility. Movement of the bubbles is believed to be assisted by ballistic collisions.
Shao Lin [Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843 (United States); Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Gorman, Brian P. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401 (United States); Aitkaliyeva, Assel [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); David Theodore, N. [CHD-Fab, Freescale Semiconductor, Inc., Chandler, Arizona 85224 (United States); Xie Guoqiang [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)
An Experiment Study of the Propagation of Radio Waves in a Scaled Model of Long-Wall Coal Mining Tunnels
A long-wall coal mining tunnel is the most important working area in a coal mine. It has long been realized that radio communications can improve both productivity and safety in this dangerous area. Hence, many attempts to use radio communications in such an environment have been made. Unfortunately, no radio system has satisfactorily provided communication services there, which, we believe, is partially due to poor understanding of the propagation characteristics of radio waves in the long-wall mining tunnel. To have deeper physical insight into the propagation problem, a scaled model of the long-wall mining tunnel was built, and the propagation characteristics of UHF radio waves were measured. The experiment and the measured results are presented and discussed.
Han, G.R.; Zhang, W.M.; Zhang, Y.P. [Shanxi University, Taiyuan (China)
Impact of metal nano layer thickness on tunneling oxide and memory performance of core-shell iridium-oxide nanocrystals
The impact of iridium-oxide (IrO{sub x}) nano layer thickness on the tunneling oxide and memory performance of IrO{sub x} metal nanocrystals in an n-Si/SiO{sub 2}/Al{sub 2}O{sub 3}/IrO{sub x}/Al{sub 2}O{sub 3}/IrO{sub x} structure has been investigated. A thinner (1.5 nm) IrO{sub x} nano layer has shown better memory performance than that of a thicker one (2.5 nm). Core-shell IrO{sub x} nanocrystals with a small average diameter of 2.4 nm and a high density of {approx}2 x 10{sup 12}/cm{sup 2} have been observed by scanning transmission electron microscopy. The IrO{sub x} nanocrystals are confirmed by x-ray photoelectron spectroscopy. A large memory window of 3.0 V at a sweeping gate voltage of {+-}5 V and 7.2 V at a sweeping gate voltage of {+-} 8 V has been observed for the 1.5 nm-thick IrO{sub x} nano layer memory capacitors with a small equivalent oxide thickness of 8 nm. The electrons and holes are trapped in the core and annular regions of the IrO{sub x} nanocrystals, respectively, which is explained by Gibbs free energy. High electron and hole-trapping densities are found to be 1.5 x 10{sup 13}/cm{sup 2} and 2 x 10{sup 13}/cm{sup 2}, respectively, due to the small size and high-density of IrO{sub x} nanocrystals. Excellent program/erase endurance of >10{sup 6} cycles and good retention of 10{sup 4} s with a good memory window of >1.2 V under a small operation voltage of {+-} 5 V are obtained. A large memory size of >10 Tbit/sq. in. can be designed by using the IrO{sub x} nanocrystals. This study is not only important for the IrO{sub x} nanocrystal charge-trapping memory investigation but it will also help to design future metal nanocrystal flash memory.
Banerjee, W.; Maikap, S. [Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, Tao-Yuan, Taiwan 333, Taiwan (China); Tien, T.-C. [Material Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan 310, Taiwan (China); Li, W.-C.; Yang, J.-R. [Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan (China)
FULL-SCALE, WIND TUNNEL AND CFD WIND ENGINEERING STUDIES A variety of methods can be used to obtain wind engineering design information. These include
FULL-SCALE, WIND TUNNEL AND CFD WIND ENGINEERING STUDIES A variety of methods can be used to obtain wind engineering design information. These include codes of practice, full-scale, wind tunnel are listed in the table below: Table 1. Relative advantages and disadvantages of wind engineering techniques
Savory, Eric
Momentum-resolved tunneling between a Luttinger liquid and a two-dimensional electron gas S. A. Grigera and A. J. Schofield
Momentum-resolved tunneling between a Luttinger liquid and a two-dimensional electron gas S. A consider momentum resolved tunneling between a Luttinger liquid and a two-dimensional electron gas on both the Luttinger liquid and the two-dimensional electron gas. We show that there are six dispersing
Grigera, Santiago
A Wind Tunnel and Theoretical Study of the Melting Behavior of Atmospheric Ice Particles. IV: Experiment and Theory for Snow Flakes
An experiment in the Mainz vertical Cloud Tunnel is described in which natural and laboratory-made aggregates of snow crystals (snow flakes) were melted under free fall conditions in the vertical air stream of the tunnel, which was allowed to ...
S. K. Mitra; O. Vohl; M. Ahr; H. R. Pruppacher
Alignment-dependent fluorescence emission induced by tunnel ionization of carbon dioxide from lower-lying orbitals
We show that fluorescence emission induced by strong field tunnel ionization of carbon dioxide from its lower-lying orbitals exhibits a peculiar molecular alignment dependence. The experimentally measured alignment-dependence of the fluorescence agrees with the alignment-dependence of the ionization probability calculated in the framework of the strong field approximation. Our results demonstrate the feasibility of an all-optical approach for shedding more light on the ionization mechanisms of molecules from their lower-lying orbitals in tunnel ionization regime.
Yao, Jinping; Jia, Xinyan; Hao, Xiaolei; Zeng, Bin; Jing, Chenrui; Chu, Wei; Ni, Jielei; Zhang, Haisu; Xie, Hongqiang; Zhang, Chaojin; Zhao, Zengxiu; Chen, Jing; Liu, Xiaojun; Cheng, Ya; Xu, Zhizhan
Giromill wind tunnel test and analysis. Volume I. Executive summary. Final report, June 1976--October 1977
The study described herein is a continuation of the Giromill investigation in which a wind tunnel test of a model Giromill rotor was performed. The primary objective of the wind tunnel test was to obtain data for comparison with the Larsen cyclogiro vortex theory program employed for predicting the Giromill performance. The model had a rotor diameter of 7 ft. (2.13 meters) and a solidity (total blade area divided by rotor span times diameter) of 0.3. This was achieved by a three bladed rotor having blade chords of 8.4 in. (21.3 cm) and a span of 5 ft. (1.52 meters). The blades were modulated by use of replaceable cams, that simulated the various operating conditions, and a push rod arrangement connected to a bellcrank about the blade pivot point. Rotor RPM control was achieved with an electric motor/generator that could be used to either drive the rotor or absorb the rotor power to maintain RPM.
Kinetics of tunneling electron transfer between antimorphous defects in optical crystals with mobile cations
The experimental data on the transient optical absorption of wide-band-gap optical crystals of lithium borates Li{sub 2}B{sub 4}O{sub 7}, LiB{sub 3}O{sub 5}, and Li{sub 6}Gd(BO{sub 3}){sub 3} and potassium (KH{sub 2}PO{sub 4} (KDP)) and ammonium (NH{sub 4}H{sub 2}PO{sub 4} (ADP)) dihydrogen phosphates in the visible and ultraviolet spectral regions are analyzed using the theory of diffusion-controlled tunneling recombination. A nanosecond pulsed radiation action on these crystals is shown to form defect pairs, such as polaron-type hole centers and electron centers based on interstitial cations. The relaxation kinetics of these centers over a wide time range of 10{sup -8}-10 s is described by a proposed model of tunneling electron transfer between antimorphous defects in the cation sublattice under the thermally stimulated mobility of recombination partners. The numerical values of the kinetic parameters are determined and the time dependences of the reaction rate constants are calculated for all crystals under study. As a result, the dynamics of change in the optical properties of these crystals under a pulsed radiation action can be simulated.
Ogorodnikov, I. N., E-mail: firstname.lastname@example.com; Kiseleva, M. S. [Ural Federal University (Russian Federation)
Patency of Femoral Tunneled Hemodialysis Catheters and Factors Predictive of Patency Failure
Purpose: To determine the patency rates of and factors associated with increased risk of patency failure in patients with femoral vein tunneled hemodialysis catheters. Methods: All femoral tunneled catheter insertions from 1996 to 2006 were reviewed, during which time 123 catheters were inserted. Of these, 66 were exchanges. Patients with femoral catheter failure versus those with femoral catheter patency were compared. Confounding factors, such as demographic and procedural factors, were incorporated and assessed using univariate and multivariable Cox proportional hazards regression analyses. Results: Mean catheter primary patency failure time was 96.3 days (SE 17.9 days). Primary patency at 30, 60, 90, and 180 days was 53.8%, 45.4%, 32.1%, and 27.1% respectively. Crude rates of risk of catheter failure did not suggest a benefit for patients receiving catheters introduced from one side versus the other, but more cephalad location of catheter tip was associated with improved patency. Multivariate analysis showed that patients whose catheters were on the left side (p = 0.009), were of increasing age at the time of insertion (p = 0.002) and that those who had diabetes (p = 0.001) were at significantly greater risk of catheter failure. The catheter infection rate was 1.4/1000 catheter days. Conclusion: Patients who were of a more advanced age and had diabetes were at greater risk of femoral catheter failure, whereas those who received femoral catheters from the right side were less at risk of catheter failure.
Burton, Kirsteen R. [University Health Network, University of Toronto, Department of Medical Imaging, Division of Vascular and Interventional Radiology (Canada); Guo, Lancia L. Q. [University of Calgary, Department of Radiology (Canada); Tan, Kong T.; Simons, Martin E.; Sniderman, Kenneth W.; Kachura, John R.; Beecroft, John R.; Rajan, Dheeraj K., E-mail: email@example.com [University Health Network, University of Toronto, Department of Medical Imaging, Division of Vascular and Interventional Radiology (Canada)
Spin-1 atoms in optical superlattices: Single-atom tunneling and entanglement
We examine spinor Bose-Einstein condensates in optical superlattices theoretically using a Bose-Hubbard Hamiltonian that takes spin effects into account. Assuming that a small number of spin-1 bosons is loaded in an optical potential, we study single-particle tunneling that occurs when one lattice site is ramped up relative to a neighboring site. Spin-dependent effects modify the tunneling events in a qualitative and quantitative way. Depending on the asymmetry of the double well, different types of magnetic order occur, making the system of spin-1 bosons in an optical superlattice a model for mesoscopic magnetism. We use a double-well potential as a unit cell for a one-dimensional superlattice. Homogeneous and inhomogeneous magnetic fields are applied, and the effects of the linear and the quadratic Zeeman shifts are examined. We also investigate the bipartite entanglement between the sites and construct states of maximal entanglement. The entanglement in our system is due to both orbital and spin degrees of freedom. We calculate the contribution of orbital and spin entanglements and show that the sum of these two terms gives a lower bound for the total entanglement.
Wagner, Andreas; Bruder, Christoph; Demler, Eugene [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)
Tunneling probability for the birth of an asymptotically de Sitter universe
In the present work, we quantize a closed Friedmann-Robertson-Walker model in the presence of a positive cosmological constant and radiation. It gives rise to a Wheeler-DeWitt equation for the scale factor which has the form of a Schroedinger equation for a potential with a barrier. We solve it numerically and determine the tunneling probability for the birth of a asymptotically DeSitter, inflationary universe, initially, as a function of the mean energy of the initial wave function. Then, we verify that the tunneling probability increases with the cosmological constant, for a fixed value of the mean energy of the initial wave function. Our treatment of the problem is more general than previous ones, based on the WKB approximation. That is the case because we take into account the fact that the scale factor (a) cannot be smaller than zero. It means that, one has to introduce an infinity potential wall at a=0, which forces any wave packet to be zero there. That condition introduces new results, in comparison with previous works.
Acacio de Barros, J. [CSLI, 220 Panama Street, Stanford University, Stanford, California 94305-4115 (United States); Correa Silva, E. V.; Monerat, G. A.; Oliveira-Neto, G. [Departamento de Matematica e Computacao, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Rodovia Presidente Dutra Km 298, Polo Industrial, CEP 27537-000, Resende-RJ (Brazil); Ferreira Filho, L. G. [Departamento de Mecanica e Energia, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Rodovia Presidente Dutra Km 298, Polo Industrial, CEP 27537-000, Resende-RJ (Brazil); Romildo, P. Jr. [Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Juiz de Fora, CEP 36036-330, Juiz de Fora, Minas Gerais (Brazil)
Property:Water Type | Open Energy Information
Type Type Jump to: navigation, search Property Name Water Type Property Type String Pages using the property "Water Type" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + Freshwater + 10-ft Wave Flume Facility + Freshwater + 11-ft Wave Flume Facility + Freshwater + 2 2-ft Flume Facility + Freshwater + 3 3-ft Wave Flume Facility + Freshwater + 5 5-ft Wave Flume Facility + Freshwater + 6 6-ft Wave Flume Facility + Freshwater + A Alden Large Flume + Freshwater + Alden Small Flume + Freshwater + Alden Tow Tank + Freshwater + Alden Wave Basin + Freshwater + B Breakwater Research Facility + Freshwater + Bucknell Hydraulic Flume + Freshwater + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + Freshwater +
Browse wiki | Open Energy Information
pressure, recirculating, cavitation tunnel with a very low acoustic background level; test section pressure: 3.5-414 kPa (0.03 to 4 atmospheres, 0.5 to 60 psia); air content: 10%...
Charge trapping characteristics of Au nanocrystals embedded in remote plasma atomic layer-deposited Al{sub 2}O{sub 3} film as the tunnel and blocking oxides for nonvolatile memory applications
Remote plasma atomic layer deposited (RPALD) Al{sub 2}O{sub 3} films were investigated to apply as tunnel and blocking layers in the metal-oxide-semiconductor capacitor memory utilizing Au nanocrystals (NCs) for nonvolatile memory applications. The interface stability of an Al{sub 2}O{sub 3} film deposited by RPALD was studied to observe the effects of remote plasma on the interface. The interface formed during RPALD process has high oxidation states such as Si{sup +3} and Si{sup +4}, indicating that RPALD process can grow more stable interface which has a small amount of fixed oxide trap charge. The significant memory characteristics were also observed in this memory device through the electrical measurement. The memory device exhibited a relatively large memory window of 5.6 V under a 10/-10 V program/erase voltage and also showed the relatively fast programming/erasing speed and a competitive retention characteristic after 10{sup 4} s. These results indicate that Al{sub 2}O{sub 3} films deposited via RPALD can be applied as the tunnel and blocking oxides for next-generation flash memory devices.
Lee, Jaesang; Kim, Hyungchul; Park, Taeyong; Ko, Youngbin; Ryu, Jaehun; Jeon, Heeyoung; Park, Jingyu; Jeon, Hyeongtag [Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea and R and D Division, Hynix Semiconductor, Inc., Icheon, Gyeonggi-do 467-701 (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea and R and D Division, Hynix Semiconductor, Inc., Icheon, Gyeonggi-do 467-701 (Korea, Republic of); Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 133-791, Korea and Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)
Lightning Safety and Large Stadiums
When lightning threatens an outdoor activity, it is usually postponed so that people may seek a safe location. When lightning threatens a large outdoor stadium, the game or event itself is usually postponed, but it is often difficult to ensure ...
Joel Gratz; Erik Noble
Large Consistent Geometric Landmark Maps
The autonomous operation of an intelligent service robot in practical applications requires that the robot builds up a map of the environment by itself, even for large environments like supermarkets. This paper presents a solution to the problem of building ...
Wolfgang D. Rencken; Wendelin Feiten; Martin Soika
Department of Energy assessment of the Large Hadron Collider
This report summarizes the conclusions of the committee that assessed the cost estimate for the Large Hadron Collider (LHC). This proton-proton collider will be built at CERN, the European Laboratory for Particle Physics near Geneva, Switzerland. The committee found the accelerator-project cost estimate of 2.3 billion in 1995 Swiss francs, or about $2 billion US, to be adequate and reasonable. The planned project completion date of 2005 also appears achievable, assuming the resources are available when needed. The cost estimate was made using established European accounting procedures. In particular, the cost estimate does not include R and D, prototyping and testing, spare parts, and most of the engineering labor. Also excluded are costs for decommissioning the Large Electron-Positron collider (LEP) that now occupies the tunnel, modifications to the injector system, the experimental areas, preoperations costs, and CERN manpower. All these items are assumed by CERN to be included in the normal annual operations budget rather than the construction budget. Finally, contingency is built into the base estimate, in contrast to Department of Energy (DOE) estimates that explicitly identify contingency. The committee`s charge, given by Dr. James F. Decker, Deputy Directory of the DOE Office of Energy Research, was to understand the basis for the LHC cost estimate, identify uncertainties, and judge the overall validity of the estimate, proposed schedule, and related issues. The committee met at CERN April 22--26, 1996. The assessment was based on the October 1995 LHC Conceptual Design Report or ``Yellow Book,`` cost estimates and formal presentations made by the CERN staff, site inspection, detailed discussions with LHC technical experts, and the committee members` considerable experience.
Flow Distortion by a Solent Sonic Anemometer: Wind Tunnel Calibration and Its Assessment for Flux Measurements over Forest and Field
Main flow distortion effects caused by the sonic probe (i.e., deflection and attenuation/amplification of the wind vector) as a function of the azimuth angle of the incoming flow were examined by means of wind tunnel measurements at four ...
A. Grelle; A. Lindroth
Drop Shapes and Axis Ratio Distributions: Comparison between 2D Video Disdrometer and Wind-Tunnel Measurements
Comparisons of drop shapes between measurements made using 2D video disdrometer (2DVD) and wind-tunnel experiments are presented. Comparisons are made in terms of the mean drop shapes and the axis ratio distributions. Very close agreement of the ...
M. Thurai; V. N. Bringi; M. Szak�ll; S. K. Mitra; K. V. Beard; S. Borrmann
Direct measurement of interfacial structure in epitaxial Gd2O3 on GaAs (001) using scanning tunneling microscopy
The epitaxial growth of Gd"2O"3 on GaAs (001) has given a low interfacial density of states, resulting in the demonstration of the first inversion-channel GaAs metal-oxide-semiconductor field-effect transistor. Motivated by the significance of this discovery, ... Keywords: Electronic information, GaAs, Gd2O3, Interfacial stacking, Scanning tunneling microscopy
Y. P. Chiu; M. C. Shih; B. C. Huang; J. Y. Shen; M. L. Huang; W. C. Lee; P. Chang; T. H. Chiang; M. Hong; J. Kwo
The Nuclear Regulatory Commission is seeking public comment on a study of how a truck cask for transporting spent nuclear fuel might perform in a severe tunnel fire. The report models the performance of the NAC International Model LWT (NAC) spent fuel cask under the conditions of the April 1982 fire in the Caldecott highway tunnel near Oakland, Calif., when a gasoline tanker carrying 8,800 gallons of gasoline overturned and caught fire. Severe, intense fires such as the Caldecott fire are extremely rare. However, they provide an opportunity to study how transportation packages might perform under very severe accident conditions. The results of this study strongly indicate that any radioactive release from the NAC model or a similar spent fuel shipping cask involved in a severe tunnel fire such as that of the Caldecott highway tunnel accident would be within regulatory limits. The peak internal temperatures predicted for the NAC cask in the analysis of the Caldecott fire scenario were not high enough to result in rupture of the fuel cladding (protective metal tubing around the fuel). Therefore, it would not be expected that any radioactive material (including spent nuclear fuel particles or fission products) would be released from the fuel rods. The maximum cask temperatures experienced around the lid, vent and drain ports exceeded the
unknown authors
Measuring charge trap occupation and energy level in CdSe/ZnS quantum dots using a scanning tunneling microscope
We use a scanning tunneling microscope to probe single-electron charging phenomena in individual CdSe/ZnS (core/shell) quantum dots (QDs) at room temperature. The QDs are deposited on top of a bare Au thin film and form a ...
Bulovic, Vladimir
Theory of tunneling magnetoresistance of an epitaxial FeMgOFe,,001... junction J. Mathon and A. Umerski
. Umerski Department of Mathematics, City University, London EC1V 0HB, United Kingdom Received 21 December is in excess of 1000% for an MgO barrier of 20 atomic planes and the spin polarization of the tunneling current atomic planes. All these results are explained qualitatively in terms of the Fe majority- and minority
Umerski, Andrey
FORCE SENSING IN SCANNING TUNNELING MICROSCOPY U. DURIG, J.K. GIMZEWSKI, D.W. POHL and R. SCHLITTLER
FORCE SENSING IN SCANNING TUNNELING MICROSCOPY U. DURIG, J.K. GIMZEWSKI, D.W. POHL and R, (1986) 930. [3] U. Durig, J.K. Gimzewski, and D.W. Pohl, Phys. Rev. Lett., in press. [4] J. Soler, A
Gimzewski, James
A theoretical investigation of ferromagnetic tunnel junctions with 4-valued conductances
In considering a novel function in ferromagnetic tunnel junctions consisting of ferromagnet(FM)/barrier/FM junctions, we theoretically investigate multiple valued (or multi-level) cell property, which is in principle realized by sensing conductances of four states recorded with magnetization configurations of two FMs; that is, (up,up), (up,down), (down,up), (down,down). To obtain such 4-valued conductances, we propose FM1/spin-polarized barrier/FM2 junctions, where the FM1 and FM2 are different ferromagnets, and the barrier has spin dependence. The proposed idea is applied to the case of the barrier having localized spins. Assuming that all the localized spins are pinned parallel to magnetization axes of the FM1 and FM2, 4-valued conductances are explicitly obtained for the case of many localized spins. Furthermore, objectives for an ideal spin-polarized barrier are discussed.
Satoshi Kokado; Kikuo Harigaya
Tunneling of Massive Dirac Fermions in Graphene through Time-periodic Potential
The energy spectrum of graphene sheet with a single barrier structure having a time periodic oscillating height and subjected to magnetic field is analyzed. The corresponding transmission is studied as function of the obtained energy and the potential parameters. Quantum interference within the oscillating barrier has an important effect on quasiparticles tunneling. In particular the time-periodic electromagnetic field generates additional sidebands at energies \\epsilon + l\\hbar \\omega (l=0,\\pm 1, \\cdots) in the transmission probability originating from the photon absorption or emission within the oscillating barrier. Due to numerical difficulties in truncating the resulting coupled channel equations we limited ourselves to low quantum channels, i.e. l=0,\\pm 1.
Ahmed Jellal; Miloud Mekkaoui; El Bouazzaoui Choubabi; Hocine Bahlouli
An apparatus for studying spallation neutrons in the Aberdeen Tunnel laboratory
In this paper, we describe the design, construction and performance of an apparatus installed in the Aberdeen Tunnel laboratory in Hong Kong for studying spallation neutrons induced by cosmic-ray muons under a vertical rock overburden of 611 meter water equivalent (m.w.e.). The apparatus comprises of six horizontal layers of plastic-scintillator hodoscopes for determining the direction and position of the incident cosmic-ray muons. Sandwiched between the hodoscope planes is a neutron detector filled with 650 kg of liquid scintillator doped with about 0.06% of Gadolinium by weight for improving the e?ciency of detecting the spallation neutrons. Performance of the apparatus is also presented.
S. C. Blyth; Y. L. Chan; X. C. Chen; M. C. Chu; R. L. Hahn; T. H. Ho; Y. B. Hsiung; B. Z. Hu; K. K. Kwan; M. W. Kwok; T. Kwok; Y. P. Lau; K. P. Lee; J. K. C. Leung; K. Y. Leung; G. L. Lin; Y. C. Lin; K. B. Luk; W. H. Luk; H. Y. Ngai; S. Y. Ngan; C. S. J. Pun; K. Shih; Y. H. Tam; R. H. M. Tsang; C. H. Wang; C. M. Wong; H. L. Wong; H. H. C. Wong; K. K. Wong; M. Yeh
Scanning tunneling microscopy reveals LiMnAs is a room temperature anti-ferromagnetic semiconductor
We performed scanning tunneling microscopy and spectroscopy on a LiMnAs(001) thin film epitaxially grown on an InAs(001) substrate by molecular beam epitaxy. While the in situ cleavage exposed only the InAs(110) non-polar planes, the cleavage continued into the LiMnAs thin layer across several facets. We combined both topography and current mappings to confirm that the facets correspond to LiMnAs. By spectroscopy we show that LiMnAs has a band gap. The band gap evidenced in this study, combined with the known Neel temperature well above room temperature, confirms that LiMnAs is a promising candidate for exploring the concepts of high temperature semiconductor spintronics based on antiferromagnets.
Wijnheijmer, A. P.; Koenraad, P. M. [COBRA Inter-University Research Institute, Department of Applied Physics, Eindhoven University of Technology, P. O. Box 513, NL-5600 MB Eindhoven (Netherlands); Marti, X. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Holy, V. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Cukr, M.; Novak, V. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Jungwirth, T. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
Magnetism of Semiconductor-Based Magnetic Tunnel Junctions under Electric Field from First Principles
Semiconductor magnetic tunnel junctions (MTJs), composed of diluted magnetic semiconductors (DMSs) sandwiching a semiconductor barrier, have potential applications in spintronics but their development has been slow due to the difficulty of controlling the magnetism of DMSs. In terms of density functional calculations for model semiconductor MTJs, (Zn,Co)O/ZnO/(Zn,Co)O and (Ga,Mn)N/GaN/(Ga,Mn)N, we show that the magnetic coupling between the transition metal ions in each DMS electrode of such semiconductor MTJs can be switched from ferromagnetic to antiferromagnetic, or vice versa, under the application of external electric field across the junctions. Our results suggest a possible avenue for the application of semiconductor MTJs.
Kan, E.; Xiang, H.; Yang, J.; Whangbo, M. H.
Actinide Sorption in Rainier Mesa Tunnel Waters from the Nevada Test Site
The sorption behavior of americium (Am), plutonium (Pu), neptunium (Np), and uranium (U) in perched Rainier Mesa tunnel water was investigated. Both volcanic zeolitized tuff samples and groundwater samples were collected from Rainier Mesa, Nevada Test Site, NV for a series of batch sorption experiments. Sorption in groundwater with and without the presence of dissolved organic matter (DOM) was investigated. Am(III) and Pu(IV) are more soluble in groundwater that has high concentrations of DOM. The sorption K{sub d} for Am(III) and Pu(IV) on volcanic zeolitized tuff was up to two orders of magnitude lower in samples with high DOM (15 to 19 mg C/L) compared to samples with DOM removed (Rainier Mesa, the low actinide Kd values measured in groundwater with high DOM concentrations must be incorporated in predictive transport models.
Zhao, P; Zavarin, M; Leif, R; Powell, B; Singleton, M; Lindvall, R; Kersting, A
Tunneling and transmission resonances of a Dirac particle by a double barrier
We calculate the tunneling process of a Dirac particle across two square barriers separated a distance $d$, as well as the scattering by a double cusp barrier where the centers of the cusps are separated a distance larger than their screening lengths. Using the scattering matrix formalism, we obtain the transmission and reflection amplitudes for the scattering processes of both configurations. We show that, the presence of transmission resonances modifies the Lorentizian shape of the energy resonances and induces the appearance of additional maxima in the transmission coefficient in the range of energies where transmission resonances occur. We calculate the Wigner time-delay and show how their maxima depend on the position of the transmission resonance.
Victor M. Villalba; Luis Gonzalez-Arraga
Applied Bias Slewing in Transient Wigner Function Simulation of Resonant Tunneling Diodes
The Wigner function formulation of quantum mechanics has shown much promise as a basis for accurately modeling quantum electronic devices, especially under transient conditions. In this work, we demonstrate the importance of using a finite applied bias slew rate (as opposed to instantaneous switching) to better approximate experimental device conditions, and thus to produce more accurate transient Wigner function simulation results. We show that the use of instantaneous (and thus unphysical) switching can significantly impact simulation results and lead to incorrect conclusions about device operation. We also find that slewed switching can reduce the high computational demands of transient simulations. The resonant tunneling diode (RTD) is used as a test device, and simulation results are produced with SQUADS (Stanford QUAntum Device Simulator). I. INTRODUCTION T HE WIGNER function formulation of quantum mechanics has proven to be a very effective basis for the numerical simulation ...
Bryan A. Biegel; Student Member; James D. Plummer
Tunneling of a Massless Field through a 3D Gaussian Barrier
We propose a method for the approximate computation of the Green function of a scalar massless field Phi subjected to potential barriers of given size and shape in spacetime. This technique is applied to the case of a 3D gaussian ellipsoid-like barrier, placed on the axis between two pointlike sources of the field. Instead of the Green function we compute its temporal integral, that gives the static potential energy of the interaction of the two sources. Such interaction takes place in part by tunneling of the quanta of Phi across the barrier. We evaluate numerically the correction to the potential in dependence on the size of the barrier and on the barrier-sources distance.
G. Modanese
Symbolic-numerical Algorithm for Generating Cluster Eigenfunctions: Tunneling of Clusters Through Repulsive Barriers
A model for quantum tunnelling of a cluster comprising A identical particles, coupled by oscillator-type potential, through short-range repulsive potential barriers is introduced for the first time in the new symmetrized-coordinate representation and studied within the s-wave approximation. The symbolic-numerical algorithms for calculating the effective potentials of the close-coupling equations in terms of the cluster wave functions and the energy of the barrier quasistationary states are formulated and implemented using the Maple computer algebra system. The effect of quantum transparency, manifesting itself in nonmonotonic resonance-type dependence of the transmission coefficient upon the energy of the particles, the number of the particles A=2,3,4, and their symmetry type, is analyzed. It is shown that the resonance behavior of the total transmission coefficient is due to the existence of barrier quasistationary states imbedded in the continuum.
Vinitsky, Sergue; Chuluunbaatar, Ochbadrakh; Rostovtsev, Vitaly; Hai, Luong Le; Derbov, Vladimir; Krassovitskiy, Pavel
Coherent destruction of tunneling in a lattice array under selective in-phase modulations
We explore the coherent destruction of tunneling (CDT) in a lattice array under selective in-phase harmonic modulations, in which some selected lattice sites are driven by in-phase harmonic oscillating fields and other lattice sites are undriven. Due to the occurrence of CDT, if the driving amplitude A and the driving frequency {omega} are tuned to satisfy the zeroth-order Bessel function J{sub 0}(A/{omega})=0, the driven lattice sites are approximately decoupled from the undriven lattice sites. The CDT even takes place in lattice systems with high-order couplings between non-nearest-neighbor lattice sites. By using the CDT induced by selective in-phase harmonic modulations, we propose a scheme for realizing directed transport of a single particle. It is possible to observe the CDT in an engineered optical waveguide array, which provides an opportunity for controlling light propagation and designing switchlike couplers.
Luo, Xiaobing [Department of Physics, Jinggangshan University, Ji'an 343009 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Huang, Jiahao; Lee, Chaohong [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)
Hydrogen adsorption on Ru(001) studied by Scanning TunnelingMicroscopy
The adsorption of hydrogen on Ru(001) was studied by scanning tunneling microscopy at temperatures around 50 K. Hydrogen was found to adsorb dissociatively forming different ordered structures as a function of coverage. In order of increasing coverage {theta} in monolayers (ML) these were ({radical}3 x {radical}3)r30{sup o} at {theta} = 0.3 ML; (2 x 1) at {theta} = 0.50 ML, (2 x 2)-3H at {theta} = 0.75, and (1 x 1) at {theta} = 1.00. Some of these structures were observed to coexist at intermediate coverage values. Close to saturation of 1 ML, H-vacancies (unoccupied three fold fcc hollow Ru sites) were observed either as single entities or forming transient aggregations. These vacancies diffuse and aggregate to form active sites for the dissociative adsorption of hydrogen.
Tatarkhanov, Mous; Rose, Franck; Fomin, Evgeny; Ogletree, D.Frank; Salmeron, Miquel
Method and apparatus for differential spectroscopic atomic-imaging using scanning tunneling microscopy
A Method and apparatus for differential spectroscopic atomic-imaging is disclosed for spatial resolution and imaging for display not only individual atoms on a sample surface, but also bonding and the specific atomic species in such bond. The apparatus includes a scanning tunneling microscope (STM) that is modified to include photon biasing, preferably a tuneable laser, modulating electronic surface biasing for the sample, and temperature biasing, preferably a vibration-free refrigerated sample mounting stage. Computer control and data processing and visual display components are also included. The method includes modulating the electronic bias voltage with and without selected photon wavelengths and frequency biasing under a stabilizing (usually cold) bias temperature to detect bonding and specific atomic species in the bonds as the STM rasters the sample. This data is processed along with atomic spatial topography data obtained from the STM raster scan to create a real-time visual image of the atoms on the sample surface.
Kazmerski, Lawrence L. (Lakewood, CO)
Development of a Digital Controller for a Vertical Wind Tunnel (VWT) Prototype to Mitigate Ball Fluctuations
The objective of this research was to mitigate fluctuations of a levitated ping pong ball within a vertical wind tunnel (VWT) prototype. This was made possible by remodeling the VWT system with its inherent nonlinear characteristics instead of assuming constant parameter relationships. By considering these nonlinearities a more accurate model was developed that better represented the actual system. The gain scheduling controller technique was chosen to control the ball�s vertical displacement within VWT prototype. After remodeling the VWT�s dynamics, the transfer function gain, for three different specified equilibrium points, were found to be within �35% of the original system dynamics� gain which explain why ball fluctuation was present. Also, three different controllers were developed to mitigate fluctuations at 0.10m, 0.15m and 0.20m. The three controllers were combined to create the gain scheduled controller; however, no testing has been done due to sudden, last minute hardware malfunction.
Silva, Ramon A.
A Wind Tunnel Study on the Shape, Oscillation, and Internal Circulation of Large Raindrops with Sizes between 2.5 and 7.5 mm
Precipitation prediction using weather radars requires detailed knowledge of the shape parameters of raindrops falling at their terminal velocities in air. Because the raindrops undergo oscillation, the most important shape parameters from the ...
Mikl�s Szak�ll; Karoline Diehl; Subir K. Mitra; Stephan Borrmann
Impact of temperature increments on tunneling barrier height and effective electron mass for plasma nitrided thin SiO{sub 2} layer on a large wafer area
Thermally grown SiO{sub 2} layers were treated by a plasma nitridation process realized in a vertical furnace. The combination of a pulsed-low frequency plasma and a microwave remote plasma with N{sub 2}/NH{sub 3}/He feed gas mixture was used to nitride the thermally grown SiO{sub 2} gate dielectrics of MIS structures. Temperature dependency of effective masses and the barrier heights for electrons in pure thermally grown SiO{sub 2} as well as plasma nitrided SiO{sub 2} in high electric field by means of Fowler-Nordheim regime was determined. It is frequently seen from the literature that either effective electron mass or barrier height (generally effective electron mass) is assumed to be a constant and, as a result, the second parameter is calculated under the chosen assumption. However, in contrast to general attitude of previous studies, this work does not make any such assumptions for the calculation of neither of these two important parameters of an oxide at temperature ranges from 23 to 110 deg. C for SiO{sub 2}, and 23 to 130 deg. C for nitrided oxide. It is also shown here that both parameters are affected from the temperature changes; respectively, the barrier height decreases while the effective mass increases as a result of elevated temperature in both pure SiO{sub 2} and plasma nitrided SiO{sub 2}. Therefore, one parameter could be miscalculated if the other parameter, i.e., effective mass of electron, was assumed to be a constant with respect to variable physical conditions like changing temperature. Additionally, the barrier heights were calculated just by taking constant effective masses for both types of oxides to be able to compare our results to common literature values.
Aygun, G. [Fraunhofer IISB, Schottkystrasse 10, 91058 Erlangen (Germany); Department of Physics, Izmir Institute of Technology, TR-35430 Urla, Izmir (Turkey); Roeder, G.; Erlbacher, T.; Wolf, M.; Schellenberger, M.; Pfitzner, L. [Fraunhofer IISB, Schottkystrasse 10, 91058 Erlangen (Germany)
Energy Extraction in the CERN Large Hadron Collider a Project Overview
In case of a resistive transition (quench), fast and reliable extraction of the magnetic energy, stored in the superconducting coils of the electromagnets of a particle collider, represents an important part of its magnet protection system. In general, the quench detectors, the quench heaters and the cold by-pass diodes across each magnet, together with the energy extraction facilities provide the required protection of the quenching superconductors against damage due to local energy dissipation. In CERN's LHC machine the energy stored in each of its eight superconducting dipole chains exceeds 1300 MJ. Following an opening of the extraction switches this energy will be absorbed in large extraction resistors located in the underground collider tunnel or adjacent galleries, during the exponential current decay. Also the sixteen, 13 kA quadrupole chains (QF, QD) and more than one hundred and fifty, 600 A circuits of the corrector magnets will be equipped with extraction systems. The extraction switch-gear is bas...
Dahlerup-Petersen, K; Kazmine, B; Medvedko, A S; Sytchev, V V; Vasilev, L B
Fast segmentation of large images
The processing of large images is a generic problem in wide area surveillance. An important difficulty is that many image processing algorithms are global rather than local and hence can be infeasible due to the required computing time or memory resources ... Keywords: algorithm, image, segmentation
David J. Crisp; Peter Perry; Nicholas J. Redding
Large Magnetization at Carbon Surfaces
Large Magnetization at Carbon Large Magnetization at Carbon Surfaces Large Magnetization at Carbon Surfaces Print Wednesday, 31 August 2011 00:00 From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided valuable insight into how proton irradiation can cause carbon to transform into a ferromagnetic material. Now, researchers are using x-ray spectroscopy at ALS Beamline 4.0.2 to study the magnetism of proton-irradiated graphite surfaces in order to understand the effects of hydrogen (i.e. protons) on the electronic structure of carbon. In studying the properties of electrons responsible for magnetic order in graphite, researchers found that a very large magnetic moment is essentially switched on when hydrogen atoms are incorporated at the surface of graphite.
Splitting and Confirming Large File
Splitting and Confirming Large File Splitting and Confirming Large File Name: Bradley C. Status: Student Age: 16 Location: N/A Country: N/A Date: June 2003 Question: I just calculated one billion digits of pi on my PC, how do I confirm them? I cannot access them because the file size is 1.28 GB, my ram is only 512 MB, meaning none of my word processor's will touch it. Is it possible to split the document, somehow? Then how do I confirm the digits? Replies: Checking the correctness of large numbers -- transcendental numbers like 'pi', or a large prime -- is not easy because there are many sources of error that are difficult to detect, or track down. Some, but by no means all are: 1. How "good" (that is convergent) is the algorithm? If, for example the algorithm is some sort of infinite series, there is always a truncation error, because you cannot compute an infinite number of terms in a finite amount of time. The further out you go in the algorithm, the more significant these errors become.
large hydro | OpenEI
large hydro large hydro Dataset Summary Description The Planning Database Project provides the UK Department of Energy and Climate Change (DECC) with regular data to track progress towards achieving EU targets for electricity generation from renewable energy (RE) sources. Extracts from the database are available each month. Information collected in the database includes: name, location and installed capacity of RE projects over 0.1MW; environmental designations; planning status; and construction status. Included here is the October 2010 Progress Datasheet, and an extract from December, 15, 2010 (i.e. Source UK Department of Energy and Climate Change (DECC) Date Released December 15th, 2010 (3 years ago) Date Updated Unknown Keywords biomass co-firing installed capacity
Large Magnetization at Carbon Surfaces Print Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided valuable insight into how proton irradiation can cause carbon to transform into a ferromagnetic material. Now, researchers are using x-ray spectroscopy at ALS Beamline 4.0.2 to study the magnetism of proton-irradiated graphite surfaces in order to understand the effects of hydrogen (i.e. protons) on the electronic structure of carbon. In studying the properties of electrons responsible for magnetic order in graphite, researchers found that a very large magnetic moment is essentially switched on when hydrogen atoms are incorporated at the surface of graphite.
Large Component Removal/Disposal
This paper describes the removal and disposal of the large components from Maine Yankee Atomic Power Plant. The large components discussed include the three steam generators, pressurizer, and reactor pressure vessel. Two separate Exemption Requests, which included radiological characterizations, shielding evaluations, structural evaluations and transportation plans, were prepared and issued to the DOT for approval to ship these components; the first was for the three steam generators and one pressurizer, the second was for the reactor pressure vessel. Both Exemption Requests were submitted to the DOT in November 1999. The DOT approved the Exemption Requests in May and July of 2000, respectively. The steam generators and pressurizer have been removed from Maine Yankee and shipped to the processing facility. They were removed from Maine Yankee's Containment Building, loaded onto specially designed skid assemblies, transported onto two separate barges, tied down to the barges, th en shipped 2750 miles to Memphis, Tennessee for processing. The Reactor Pressure Vessel Removal Project is currently under way and scheduled to be completed by Fall of 2002. The planning, preparation and removal of these large components has required extensive efforts in planning and implementation on the part of all parties involved.
Wheeler, D. M.
Development and Application of a Three-Dimensional Taylor�Galerkin Numerical Model for Air Quality Simulation near Roadway Tunnel Portals
Since highway traffic has become one of the major emission sources of air pollution, air pollution prediction near roadway tunnel portals is a very important subject. Although many models have been suggested to predict pollutant concentrations ...
Shin�ichi Okamoto; Kazuhiro Sakai; Koichi Matsumoto; Kenji Horiuchi; Keizo Kobayashi
Forced Boundary-Layer Transition on X-43 (Hyper-X) in NASA LaRC 31-Inch Mach 10 Air Tunnel
Aeroheating and boundary layer transition characteristics for the X-43 (Hyper-X) configuration have been experimentally examined in the Langley 31-Inch Mach 10 Air Tunnel. Global surface heat transfer distributions, and surface streamline patterns were ...
Berry Scott A.; DiFulvio Michael; Kowalkowski Matthew K.
Forced Boundary-Layer Transition on X-43 (Hyper-X) in NASA LaRC 20-Inch Mach 6 Air Tunnel
Aeroheating and boundary layer transition characteristics for the X-43 (Hyper-X) configuration have been experimentally examined in the Langley 20-Inch Mach 6 Air Tunnel. Global surface heat transfer distributions, and surface streamline patterns were ...
X-ray absorption and magnetic circular dichroism studies of Co2FeAl in magnetic tunnel junctions
The bulk magnetic moment and the element specific magnetic moment of Co{sub 2}FeAl thin films were examined as a function of annealing temperature by alternating gradient magnetometer (AGM) and X-ray absorption spectroscopy (XAS)/X-ray magnetic circular dichroism (XMCD), respectively. A high magnetic moment can be achieved for all annealing temperatures and the predicted bulk and interface magnetic moment of about 5 {tilde A}{sub B} are reached via heating. We will also present tunnel magnetoresistance (TMR) values of up to 153% at room temperature and 260% at 13 K for MgO based magnetic tunnel junctions (MTJs) with Co{sub 2}FeAl and Co-Fe electrodes.
Ebke, D.; Kugler, Z.; Thomas, P.; Schebaum, O.; Schafers, M.; Nissen, D.; Schmalhorst, J.; Hutten, A.; Arenholz, E.; Thomas, A.
Homogeneous pinhole free 1 nm Al{sub 2}O{sub 3} tunnel barriers on graphene
We report on the topographical and electrical characterisations of 1 nm thick Al{sub 2}O{sub 3} dielectric films on graphene. The Al{sub 2}O{sub 3} is grown by sputtering a 0.6 nm Al layer on graphene and subsequentially oxidizing it in an O{sub 2} atmosphere. The Al{sub 2}O{sub 3} layer presents no pinholes and is homogeneous enough to act as a tunnel barrier. A resistance-area product in the mega-ohm micrometer-square range is found. Comparatively, the growth of Al{sub 2}O{sub 3} by evaporation does not lead to well-wetted films on graphene. Application of this high quality sputtered tunnel barrier to efficient spin injection in graphene is discussed.
Dlubak, B.; Martin, M.-B.; Deranlot, C.; Bouzehouane, K.; Fusil, S.; Mattana, R.; Petroff, F.; Anane, A.; Seneor, P.; Fert, A. [Unite Mixte de Physique CNRS/Thales, 91767 Palaiseau (France) and University of Paris-Sud, 91405 Orsay (France)
CALIFORNIA ENERGY Large HVAC Energy Impact Report
CALIFORNIA ENERGY COMMISSION Large HVAC Energy Impact Report Statewide Energy Impact Report are part of the Integrated Design of Large Commercial HVAC Systems research project. The reports: Productivity and Interior Environments Integrated Design of Large Commercial HVAC Systems Integrated Design
the Large Aperture GRB Observatory
The Large Aperture GRB Observatory (LAGO) aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique (SPT) in ground based water Cherenkov detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550 m a.s.l.), Bolivia (Chacaltaya, 5300 m a.s.l.) and Venezuela (Merida, 4765 m a.s.l.). We report on the project progresses and the first operation at high altitude, search for bursts in 6 months of preliminary data, as well as search for signal at ground level when satellites report a burst.
Bertou, Xavier [Centro Atomico Bariloche (Argentina)
Aggregation in Large Dynamic Panels
;, and as = E (w0#8;s#28; ) = E(#21;s). Hence, for su� ciently large N and T , the distributed lag coe� cients can be consistently estimated by bas = 1N PN i=1 b#21;si , where b#21;i is the least square estimator of #21;i in the autoregressions (30... ). The distribution F#21; is not the same as the distribution of b#21;i when T is ?nite, but bas is consistent at least when T ! 1 followed by N ! 1. Both the aggregate and the disaggregate estimators are biased when T is small. Initially, we also report the estimates...
Pesaran, M. Hashem; Chudik, Alexander
The Large Aperture GRB Observatory
The Large Aperture GRB Observatory (LAGO) is aiming at the detection of the high energy (around 100 GeV) component of Gamma Ray Bursts, using the single particle technique in arrays of Water Cherenkov Detectors (WCD) in high mountain sites (Chacaltaya, Bolivia, 5300 m a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m a.s.l). WCD at high altitude offer a unique possibility of detecting low gamma fluxes in the 10 GeV - 1 TeV range. The status of the Observatory and data collected from 2007 to date will be presented.
Allard, D; Asorey, H; Barros, H; Bertou, X; Castillo, M; Chirinos, J M; De Castro, A; Flores, S; Gonz�lez, J; Berisso, M Gomez; Grajales, J; Guada, C; Day, W R Guevara; Ishitsuka, J; L�pez, J A; Mart�nez, O; Melfo, A; Meza, E; Loza, P Miranda; Barbosa, E Moreno; Murrugarra, C; N��ez, L A; Ormachea, L J Otiniano; P�rez, G; Perez, Y; Ponce, E; Quispe, J; Quintero, C; Rivera, H; Rosales, M; Rovero, A C; Saavedra, O; Salazar, H; Tello, J C; Peralda, R Ticona; Varela, E; Velarde, A; Villase�or, L; Wahl, D; Zamalloa, M A
Preliminary numerical modeling for the G-Tunnel welded tuff mining experiment; Yucca Mountain site characterization project
Yucca Mountain, located in Southern Nevada, is to be considered as a potential site for a nuclear waste repository. Located in Rainier Mesa on the Nevada Test Site, G-Tunnel has been the site of a series of experiments, part of whose purpose is to evaluate measurement techniques for rock mechanics before testing in the Exploratory Shaft. Rainier Mesa is composed of welded and nonwelded tuffs that have thermal and mechanical properties and stress states similar to those of tuffs expected to be encountered at Yucca Mountain. A series of finite element calculations were performed to aid in designing instrumentation for the experiments in G-Tunnel and later to correlate with measured data. In this report are presented the results of the preliminary finite element calculations performed in conjunction with experimental measurements of drift convergence, or closure, and rock mass relaxation zones made before, during, and after completing the welded tuff mining experiment in G-Tunnel. Tape extensometer measurements of drift convergences and measurements determined by multiple point borehole extensometers are compared with corresponding calculated values using linear elastic and jointed rock material models. 9 refs., 25 figs., 7 tabs.
Johnson, R.L.; Bauer, S.J.
Director's colloquium March 18 large hadron collider
Director's colloquium large hadron collider Director's colloquium March 18 large hadron collider Lyndon Evans of CERN will talk about the most complex scientific instrument ever...
Property:Hydrodynamic Testing Facility Type | Open Energy Information
Hydrodynamic Testing Facility Type Hydrodynamic Testing Facility Type Jump to: navigation, search Property Name Hydrodynamic Testing Facility Type Property Type Page Pages using the property "Hydrodynamic Testing Facility Type" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + Flume + 10-ft Wave Flume Facility + Flume + 11-ft Wave Flume Facility + Flume + 2 2-ft Flume Facility + Flume + 3 3-ft Wave Flume Facility + Flume + 5 5-ft Wave Flume Facility + Flume + 6 6-ft Wave Flume Facility + Flume + A Alden Large Flume + Flume + Alden Small Flume + Flume + Alden Tow Tank + Tow Tank + Alden Wave Basin + Wave Basin + B Breakwater Research Facility + Wave Basin + Bucknell Hydraulic Flume + Flume + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + Tunnel +
Scanning tunneling microscopy observation of Pb-induced superstructures on Si(557)
Pb-induced superstructures on Si(557) are investigated by low-energy-electron diffraction (LEED) and scanning tunneling microscopy (STM). Using an indirect heating method, we have succeeded in obtaining almost perfect single-domain LEED patterns of one-dimensional wire (chain) structures, so called {alpha}x2 and {beta}x2 phases. Careful LEED analysis and STM investigation reveal that these phases are formed on the (223) and (112) facets, respectively. The {alpha}x2 phase has regular bundles of triple wires at low annealing temperature but wider bundles through step bunching after a higher temperature annealing. Along the wires of the {alpha}x2 phase, which was recently reported to exhibit a transition between one-dimensional (1D) metallic and 2D semiconducting conductance, a clear commensurate x2 modulation is observed at 78-120 K in contrast to the incommensurate and disordered structure reported previously. A tentative atomic structure model of the {alpha}x2 phase is proposed based on the dense Pb overlayers on (111) and (223) facets. The details of the STM images of the {beta}x2 phase are discussed.
Morikawa, Harumo; Kim, Keun Su; Jung, Duk Yong; Yeom, Han Woong [Institute of Physics and Applied Physics and Center for Atomic Wires and Layers, Yonsei University, 134 Shinchon, Seoul 120-749 (Korea, Republic of)
Environmental quality indexing of large industrial development alternatives using AHP
Two industrial development alternatives have been proposed for the East Coast of Iceland in order to strengthen its socio-economic basis. The favoured option is to build a large aluminium smelter, which requires massive hydropower development in the nearby highlands. Another viable option is the construction of a 6-million-ton oil refinery, following the planned exploitation of the Timan Pechora oil reserves in the Russian Arctic. A third 'fictitious' alternative could be general development of existing regional industry and new knowledge-based industries, development of ecotourism, establishment of national parks, accompanied by infrastructure improvement (roads, tunnels, communications, schools, etc.). The three alternatives will have different environmental consequences. The controversial hydropower plant for the smelter requires a large water reservoir as well as considerable land disturbance in this unique mountain territory, considered to be the largest uninhabited wilderness in Western Europe. The aluminium smelter and the oil refinery will give rise to substantial increase of the greenhouse gas (GHG) emissions of the country (about 20%). Then there is potential environmental risk associated with the refinery regarding oil spills at sea, which could have disastrous impact on the fisheries industry. However, the oil refinery does not require any hydropower development, which is a positive factor. Finally, the third alternative could be defined as a ''green'' solution whereby the detrimental environmental consequences of the two industrial solutions are mostly avoided. In order to compare the three alternatives in an orderly manner, the analytic hierarchy process methodology of Saaty was applied to calculate the environmental quality index of each alternative, which is defined as a weighted sum of selected environmental and socio-economic factors. These factors are evaluated on a comparison basis, applying the AHP methodology, and the weights in the quality index summation are estimated in the same manner. Six persons with different backgrounds were asked to fill in the comparison matrices in order to reduce bias in the evaluation. The final results show that the two industrial alternatives come out poorly, i.e. with low quality indices, whereas the third pseudo-alternative, i.e. general development, with a considerably higher quality index, is certainly worth a further study.
Solnes, Julius
Understanding Cavitation Erosion Mechanism in Friction Stir ...
... Modeling Approach to Develop Protective Coatings for Fossil Energy Applications ... Doped Solid Oxide Fuel Cell Electrolytes Produced Via a Combination of�...
Considerations Regarding Cavitation Erosion Behavior of Hydraulic ...
The development and design of a large bakeable valve based on a unique seat arrangement and a novel motion seal are described. The seat sealing is accomplished through the use of high pressure fluid actuation of an annular pinch gasket. Experimental data on seat closure performance, and the specific design features to achieve successful closures, are presented. The bakeable motion seal utilizes a stainless steel bellows sleeving over an inner concentric actuating shaft. This shaft is bent at 90 deg to the axis of rotation and is free to rotate relative to the bellows. There is no apparent size limitation to this type of actuation. The design of a 10-inch gate valve utilizing these principles is described. (auth)
Batzer, T.H.
Analysis of large urban fires
Fires in urban areas caused by a nuclear burst are analyzed as a first step towards determining their smoke-generation chacteristics, which may have grave implications for global-scale climatic consequences. A chain of events and their component processes which would follow a nuclear attack are described. A numerical code is currently being developed to calculate ultimately the smoke production rate for a given attack scenario. Available models for most of the processes are incorporated into the code. Sample calculations of urban fire-development history performed in the code for an idealized uniform city are presented. Preliminary results indicate the importance of the wind, thermal radiation transmission, fuel distributions, and ignition thresholds on the urban fire spread characteristics. Future plans are to improve the existing models and develop new ones to characterize smoke production from large urban fires. 21 references, 18 figures.
Kang, S.W.; Reitter, T.A.; Takata, A.N.
Terrestrial LiDAR in tunnels under construction : A study of potential use for engineering geological and operational applications, and work-flow design for data acquisition and processing.
??This thesis provides an assessment of the application of terrestrial LiDAR for rock mass characterisation and support design in drill and blast tunnels. The study� (more)
Haugland, Heidi Hefre
The sorption behavior of americium (Am), plutonium (Pu), neptunium (Np), and uranium (U) in perched Rainier Mesa tunnel water was investigated. Both volcanic zeolitized tuff samples and groundwater samples were collected from Rainier Mesa, Nevada Test Site, NV for a series of batch sorption experiments. Sorption in groundwater with and without the presence of dissolved organic matter (DOM) was investigated. Am(III) and Pu(IV) are more soluble in groundwater that has high concentrations of DOM. The sorption K{sub d} for Am(III) and Pu(IV) on volcanic zeolitized tuff was up to two orders of magnitude lower in samples with high DOM (15 to 19 mg C/L) compared to samples with DOM removed (< 0.4 mg C/L) or samples with naturally low DOM (0.2 mg C/L). In contrast, Np(V) and U(VI) sorption to zeolitized tuff was much less affected by the presence of DOM. The Np(V) and U(VI) sorption Kds were low under all conditions. Importantly, the DOM was not found to significantly sorb to the zeolitized tuff during these experiment. The concentration of DOM in groundwater affects the transport behavior of actinides in the subsurface. The mobility of Am(III) and Pu(IV) is significantly higher in groundwater with elevated levels of DOM resulting in potentially enhanced transport. To accurately model the transport behavior of actinides in groundwater at Rainier Mesa, the low actinide Kd values measured in groundwater with high DOM concentrations must be incorporated in predictive transport models.
Scanning tunneling microscopy of charge density wave structure in 1T- TaS sub 2
I have used a scanning tunneling microscope (STM) to image simultaneously the atomic lattice and the charge density wave (CDW) superstructure in tantalum disulfide (1T-TaS{sub 2}) over the temperature range of 370-77K. In the lowest temperature (commensurate) phase, present below 180K, the CDW is at an angle of 13.9{degrees} relative to the lattice and is uniformly commensurate. In the incommensurate phase, present above 353K, the CDW is aligned with the lattice. 1T-TaS{sub 2} exhibits two other phases; the triclinic (T) phase which is present between 223K and 283K upon warming the sample, and the nearly-commensurate (NC) phase which is present between 353K and 180K upon cooling the sample and between 283K and 353K upon warming the sample. In both of these phases, discommensurate models where the CDW is arranged in small commensurate domains have been proposed. In the NC phase the CDW is rotated between 10{degrees} and 12.5{degrees} relative to the atomic lattice. Such a rotated CDW would create an interference pattern with the underlying atomic lattice regardless of the existence of a true domain superstructure. Previous work on 1T-TaS{sub 2} has not adequately accounted for the possibility of this moire pattern. However, around each fundamental CDW peak in the Fourier transform of the real space STM images, several satellite spots are visible, which conclusively prove the existence of domains in the NC phase.
Thomson, R.E.
Scanning tunneling microscopy of charge density wave structure in 1T- TaS{sub 2}
Low temperature tunneling magnetoresistance on (La,Sr)MnO{sub 3}/Co junctions with organic spacer layers
This paper concerns with giant magnetoresistance (MR) effects in organic spin valves, which are realized as layered (La,Sr)MnO{sub 3} (LSMO)-based junctions with tris-(8, hydroxyquinoline) aluminum (Alq{sub 3})-spacer and ferromagnetic top layers. The experimental work was focused on the understanding of the transport behavior in this type of magnetic switching elements. The device preparation was carried out in an ultrahigh vacuum chamber equipped with a mask changer by evaporation and sputtering on SrTiO{sub 3} substrates with LSMO stripes deposited by pulsed laser technique. The field and temperature dependences of the MR of the prepared elements are studied. Spin-valve effects at 4.2 K have been observed in a broad resistance interval from 50 {omega} to M{omega} range, however, without systematic dependence on spacer layer thickness and device area. In some samples, the MR changes sign as a function of the bias voltage. The observed similarity in the bias voltages dependences of the MR in comparison with conventional magnetic tunnel junctions with oxide barriers suggests a description of the found effects within the classical tunneling concept. This assumption is also confirmed by a similar switching behavior observed on ferromagnetically contacted carbon nanotube devices. The proposed model implies the realization of the transport via local Co chains embedded in the Alq{sub 3} layer and spin dependent tunneling over barriers at the interface Co grains/Alq{sub 3}/LSMO. The existence of conducting Co chains within the organics is supported by transmission electron microscopic/electron energy loss spectroscopic studies on cross-sectional samples from analogous layer stacks.
Vinzelberg, H.; Schumann, J.; Elefant, D.; Gangineni, R. B.; Thomas, J.; Buechner, B. [Leibniz Institute for Solid State and Materials Research Dresden, IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)
The dark resonances in the case of the absorption of optical radiation in double tunneling-coupled quantum wells
This work is devoted to the research of conditions of the dark resonance (coherent population trapping) of the interaction of the laser radiation with tunneling-coupled quantum wells. The phase sensitive dependence of dark resonances has been investigated. We obtained that destruction as well as restoration of the dark resonances of the coherent population trapping is possible in dependence on algebraic sum of the phases of exciting fields. It is shown that the phase variation of exciting fields influences on the absorption and dispersion of the probe field in a medium with quantum wells.
A. N. Litvinov; K. A. Barantsev; B. G. Matisov; G. A. Kazakov; Yu. V. Rozhdestvensky
Evidence of a barrier oxidation dependence on the interfacialmagnetism in co/alumina based magnetic tunnel junctions
Soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co L{sub 2,3} edge have been applied to explore the near-interfacial magnetism of Co electrodes in Co/alumina based magnetic tunnel junctions. By taking into account the formation of CoO at the FM/barrier interface, the change in the total magnetic moment on metallic Co atoms as a function of barrier oxidation has been determined. The results demonstrate a strong correlation between the Co moments and measured TMR values, and an enhancement in the Co moments for moderate oxidation times.
Telling, N.D.; van der Laan, G.; Ladak, S.; Hicken, R.J.; Arenholz, E.
Scanning-tunneling-microscopy studies of disilane adsorption and pyrolytic growth on Si(100)-(2x1)
Scanning tunneling microscopy has been employed to study the adsorption of disilane (Si{sub 2}H{sub 6}) and pyrolytic growth on Si(100)-(2{times}1) at various temperatures. Room-temperature exposures result in a random distribution of dissociation fragments on the surface. Formation of anisotropic monohydride islands and denuded zones as well as island coarsening is observed at higher temperatures. The results are strikingly similar to those reported for growth by molecular-beam epitaxy using pure Si, even though different surface reactions are involved in these two growth processes.
Lin, D.; Hirschorn, E.S.; Chiang, T. (Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)); Tsu, R.; Lubben, D.; Greene, J.E. (Department of Materials Science, Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States) Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States))
Novel Lamination Method for Large Armor Panels
New Saccharification Process of Cellulosic Biomass by Microwave Irradiation � Novel Lamination Method for Large Armor Panels � Raman Spectroscopy for�...
Energy Basics: Large-Scale Hydropower
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Energy Basics Renewable Energy Printable Version Share this resource Biomass Geothermal Hydrogen Hydropower Large-Scale Hydropower Microhydropower Hydropower Resources...
Property:Depth(m) | Open Energy Information
Depth(m) Depth(m) Jump to: navigation, search This is a property of type String. Pages using the property "Depth(m)" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + 0.9 + 10-ft Wave Flume Facility + 1.5 + 11-ft Wave Flume Facility + 1.8 + 2 2-ft Flume Facility + 1.8 + 3 3-ft Wave Flume Facility + 0.9 + 5 5-ft Wave Flume Facility + 1.5 + 6 6-ft Wave Flume Facility + 1.8 + A Alden Large Flume + 3.0 + Alden Small Flume + 1.8 + Alden Tow Tank + 1.2 + Alden Wave Basin + 1.2 + B Breakwater Research Facility + 0.8 + Bucknell Hydraulic Flume + 0.6 + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + 0.6 + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + 0.7 + Carderock Circulating Water Channel + 2.7 +
Property:Beam(m) | Open Energy Information
Beam(m) Beam(m) Jump to: navigation, search This is a property of type String. Pages using the property "Beam(m)" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + 0.5 + 10-ft Wave Flume Facility + 3.0 + 11-ft Wave Flume Facility + 3.4 + 2 2-ft Flume Facility + 0.6 + 3 3-ft Wave Flume Facility + 0.9 + 5 5-ft Wave Flume Facility + 1.5 + 6 6-ft Wave Flume Facility + 1.8 + A Alden Large Flume + 6.1 + Alden Small Flume + 1.8 + Alden Tow Tank + 1.2 + Alden Wave Basin + 21.3 + B Breakwater Research Facility + 55.5 + Bucknell Hydraulic Flume + 1.2 + C Carderock 2-ft Variable Pressure Cavitation Water Tunnel + 0.6 + Carderock 3-ft Variable Pressure Cavitation Water Tunnel + 0.7 + Carderock Circulating Water Channel + 6.7 +
A Large-Scale Matched-Index-of-Refraction Flow Facility for LDA Studies Around Complex Geometrics
Abstract Useage of laser-Doppler anemometry (LDA) requires optical access to the flow field of interest. This has not always proved easy, as in the case of complex geometries or very near-wall boundary layer measurements. One solution is to employ a solid material and fluid with the same refractive index. In this case, there is no optical interference of the solid with the LDA. Although this technique is not new, previous studies have been limited to small flow apparatus and relatively unpleasant fluids. A large-scale flow tunnel has now been constructed, permitting matched index of refraction LDA measurements in difficult geometries, higher Reynolds numbers, and increased spatial resolution in the measurements. This paper describes the facility and fluid flow quality, and presents some preliminary results for very near-wall measurements of a transitional boundary layer behind a roughness element.
Stoots, Carl Marcel; Condie, Keith Glenn; McEligot, Donald Marinus; Becker, S.; Durst, F.
Virtual screening on large scale grids
Large scale grids for in silico drug discovery open opportunities of particular interest to neglected and emerging diseases. In 2005 and 2006, we have been able to deploy large scale virtual docking within the framework of the WISDOM initiative against ... Keywords: Avian influenza, Large scale grids, Malaria, Virtual screening
Nicolas Jacq; Vincent Breton; Hsin-Yen Chen; Li-Yung Ho; Martin Hofmann; Vinod Kasam; Hurng-Chun Lee; Yannick Legr�; Simon C. Lin; Astrid Maa�; Emmanuel Medernach; Ivan Merelli; Luciano Milanesi; Giulio Rastelli; Matthieu Reichstadt; Jean Salzemann; Horst Schwichtenberg; Ying-Ta Wu; Marc Zimmermann
Scanning tunneling microscopic studies of SiO2 thin film supported metal nano-clusters
This dissertation is focused on understanding heterogeneous metal catalysts supported on oxides using a model catalyst system of SiO2 thin film supported metal nano-clusters. The primary technique applied to this study is scanning tunneling microscopy (STM). The most important constituent of this model catalyst system is the SiO2 thin film, as it must be thin and homogeneous enough to apply electron or ion based surface science techniques as well as STM. Ultra-thin SiO2 films were successfully synthesized on a Mo(112) single crystal. The electronic and geometric structure of the SiO2 thin film was investigated by STM combined with LEED, Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The relationship between defects on the SiO2 thin film and the nucleation and growth of metal nano-clusters was also investigated. By monitoring morphology changes during thermal annealing, it was found that the metal-support interaction is strongly dependent on the type of metal as well as on the defect density of the SiO2 thin film. Especially, it was found that oxygen vacancies and Si impurities play an important role in the formation of Pd-silicide. By substituting Ti atoms into the SiO2 thin film network, an atomically mixed TiO2-SiO2 thin film was synthesized. Furthermore, these Ti atoms play a role as heterogeneous defects, resulting in the creation of nucleation sites for Au nano-clusters. A marked increase in Au cluster density due to Ti defects was observed in STM. A TiO2-SiO2 thin film consisting of atomic Ti as well as TiOx islands was also synthesized by using higher amounts of Ti (17 %). More importantly, this oxide surface was found to have sinter resistant properties for Au nano-clusters, which are desirable in order to make highly active Au nano-clusters more stable under reaction conditions.
Min, Byoung Koun
Scanning tunneling microscopy studies on the structure and stability of model catalysts
An atomic level understanding of the structure and stability of model catalysts is essential for surface science studies in heterogeneous catalysis. Scanning tunneling microscopy (STM) can operate both in UHV and under realistic pressure conditions with a wide temperature span while providing atomic resolution images. Taking advantage of the ability of STM, our research focuses on 1) investigating the structure and stability of supported Au catalysts, especially under CO oxidation conditions, and 2) synthesizing and characterizing a series of alloy model catalysts for future model catalytic studies. In our study, Au clusters supported on TiO2(110) have been used to model supported Au catalysts. Our STM studies in UHV reveal surface structures of TiO2(110) and show undercoordinated Ti cations play a critical role in the nucleation and stabilization of Au clusters on TiO2(110). Exposing the TiO2(110) surface to water vapor causes the formation of surface hydroxyl groups and subsequently alters the growth kinetics of Au clusters on TiO2(110). STM studies on Au/TiO2(110) during CO oxidation demonstrate the real surface of a working catalyst. Au clusters supported on TiO2(110) sinter rapidly during CO oxidation, but are mostly stable in the single component reactant gas, either CO or O2. The sintering kinetics of supported Au clusters has been measured during CO oxidation and gives an activation energy, which supports the mechanism of CO oxidation induced sintering. CO oxidation was also found to accelerate the surface diffusion of Rh(110). Our results show a direct correlation between the reaction rate of CO oxidation and the diffusion rate of surface metal atoms. Synthesis of alloy model catalysts have also been attempted in our study with their structures successfully characterized. Planar Au-Pd alloy films has been prepared on a Rh(100) surface with surface Au and Pd atoms distinguished by STM. The growth of Au-Ag alloy clusters have been studied by in-situ STM on a cluster-to-cluster basis. Moreover, the atomic structure of a solution-prepared Ru3Sn3 cluster has been resolved on an ultra-thin silica film surface. The atomic structure and adsorption sites of the ultrathin silica film have also been well characterized in our study.
Yang, Fan
High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode
We present an approach for the highly sensitive photon detection based on the quantum dots (QDs) operating at temperature of 77K. The detection structure is based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons per second had induced 10nA photocurrent in this structure, corresponding to the photo-excited carrier multiplication factor of 10^7. This high multiplication factor is achieved by the quantum dot induced memory effect and the resonant tunneling tuning effect of QD-RTD structure.
Wang, Wangping; Xiong, Dayuan; Li, Ning; Lu, Wei
Wangping Wang; Ying Hou; Dayuan Xiong; Ning Li; Wei Lu
A preliminary evaluation of the performance of wind tunnel and numerical modeling simulations of the wind flow over a wind farm
This report is an analysis of physical and numerical model simulations of the wind flow over complex terrain. The specific area to which these models were applied is a wind farm in the Altamont Pass area of California. The physical model results were obtained from wind tunnel flow simulations, and the numerical model used was the optimizing version of the NOABL model. The goals of this analysis were (1) to evaluate the relative performance of the two models and (2) to uncover any clues that would point toward improvement of the wind tunnel modeling. The performances of the models were gauged by comparing model simulations to wind observations taken over the modeled area.
Barnard, J.C.; Wegley, H.L.
NREL Unsteady Aerodynamics Experiment in the NASA-Ames Wind Tunnel: A Comparison of Predictions to Measurements
Currently, wind turbine designers rely on safety factors to compensate for the effects of unknown loads acting on the turbine structure. This results in components that are overdesigned because precise load levels and load paths are unknown. To advance wind turbine technology, the forces acting on the turbine structure must be accurately characterized because these forces translate directly into loads imparted to the wind turbine structure and resulting power production. Once these forces are more accurately characterized, we will better understand load paths and can therefore optimize turbine structures. To address this problem, the National Renewable Energy Laboratory (NREL) conducted the Unsteady Aerodynamics Experiment (UAE), which was a test of an extensively instrumented wind turbine in the giant NASA-Ames 24.4-m (80 feet) by 36.6-m (120 feet) wind tunnel. To maximize the benefits from testing, NREL formed a Science Panel of advisers comprised of wind turbine aerodynamics and modeling experts throughout the world. NREL used the Science Panel's guidance to specify the conditions and configurations under which the turbine was operated in the wind tunnel. The panel also helped define test priorities and objectives that would be effective for wind turbine modeling tool development and validation.
Simms, D.; Schreck, S.; Hand, M.; Fingersh, L.J.
Variational transition state theory calculations of tunneling effects on concerted hydrogen motion in water clusters and formaldehyde/water clusters
The direct participation of water molecules in aqueous phase reaction processes has been postulated to occur via both single-step mechanisms as well as concerted hydrogen atom or proton shifts. In the present work, simple prototypes of concerted hydrogen atom transfer processes are examined for small hydrogen-bonded water clusters -- cyclic trimers and tetramers -- and hydrogen-bonded clusters of formaldehyde with one and two water molecules. Rate constants for the rearrangement processes are computed using variational transition state theory, accounting for quantum mechanical tunneling effects by semiclassical ground-state adiabatic transmission coefficients. The variational transition state theory calculations directly utilize selected information about the potential energy surface along the minimum energy path as parameters of the reaction path Hamiltonian. The potential energy information is obtained from ab ignite electronic structure calculations with an empirical bond additivity correction (the BAC-MP4 method). Tunneling is found to be very important for these concerted rearrangement processes -- the semiclassical ground-state adiabatic transmission coefficients are estimated to be as high as four order of magnitude at room temperature. Effects of the size of the cluster (number of water molecules in the cyclic complex) are also dramatic -- addition of a water molecule is seen to change the calculated rates by orders of magnitude. 36 refs., 10 figs.
Garrett, B.C. (Pacific Northwest Lab., Richland, WA (USA)); Melius, C.F. (Sandia National Labs., Livermore, CA (USA))
and Large Sized Chinese Steel Enterprises
Analysis of the Past and Future Trends of Energy Use in Key Medium and Large Sized Chinese Steel Enterprises year month institution Lawrence Berkeley National Laboratory abstract p...
International Conference on Accelerator and Large Experimental...
and Large Experimental Physics Control Systems Covering control system topics for accelerators, telescopes, fusion, physics detectors, space exploration, and more Proceedings...
NREL: Wind Research - Large Wind Turbine Research
Wind Research Search More Search Options Site Map Printable Version Large Wind Turbine Research NREL's utility scale wind system research addresses performance and...
Large Neighborhood Search for LNG Inventory Routing
Feb 3, 2012 ... Large Neighborhood Search for LNG Inventory Routing. Vikas Goel (vikas.goel ** *at*** exxonmobil.com) Kevin Furman (kevin.c.furman ***at***�...
Adsorbate structures and catalytic reactions studied in the torrpressure range by scanning tunneling microscopy
High-pressure, high-temperature scanning tunneling microscopy (HPHTSTM) was used to study adsorbate structures and reactions on single crystal model catalytic systems. Studies of the automobile catalytic converter reaction [CO + NO {yields} 1/2 N{sub 2} + CO{sub 2}] on Rh(111) and ethylene hydrogenation [C{sub 2}H{sub 4} + H{sub 2} {yields} C{sub 2}H{sub 6}] on Rh(111) and Pt(111) elucidated information on adsorbate structures in equilibrium with high-pressure gas and the relationship of atomic and molecular mobility to chemistry. STM studies of NO on Rh(111) showed that adsorbed NO forms two high-pressure structures, with the phase transformation from the (2 x 2) structure to the (3 x 3) structure occurring at 0.03 Torr. The (3 x 3) structure only exists when the surface is in equilibrium with the gas phase. The heat of adsorption of this new structure was determined by measuring the pressures and temperatures at which both (2 x 2) and (3 x 3) structures coexisted. The energy barrier between the two structures was calculated by observing the time necessary for the phase transformation to take place. High-pressure STM studies of the coadsorption of CO and NO on Rh(111) showed that CO and NO form a mixed (2 x 2) structure at low NO partial pressures. By comparing surface and gas compositions, the adsorption energy difference between topsite CO and NO was calculated. Occasionally there is exchange between top-site CO and NO, for which we have described a mechanism for. At high NO partial pressures, NO segregates into islands, where the phase transformation to the (3 x 3) structure occurs. The reaction of CO and NO on Rh(111) was monitored by mass spectrometry (MS) and HPHTSTM. From MS studies the apparent activation energy of the catalytic converter reaction was calculated and compared to theory. STM showed that under high-temperature reaction conditions, surface metal atoms become mobile. Ethylene hydrogenation and its poisoning by CO was also studied by STM on Rh(111) and Pt(111). Poisoning was found to coincide with decreased adsorbate mobility. Under ethylene hydrogenation conditions, no order is detected by STM at 300 K, as hydrogen and ethylidyne, the surface species formed by gas-phase ethylene, are too mobile. When CO is introduced, the reaction stops, and ordered structures appear on the surface. For Rh(111), the structure is predominantly a mixed c(4 x 2), though there are some areas of (2 x 2). For Pt(111), the structure is hexagonal and resembles the Moire pattern seen when Pt(111) is exposed to pure CO. From these studies it is concluded that CO poisons by stopping adsorbate mobility. This lack of adsorbate mobility prevents the adsorption of ethylene from the gas phase by hindering the creation of adsorption sites.
Hwang, Kevin Shao-Lin
Wind Tunnel Aerodynamic Tests of Six Airfoils for Use on Small Wind Turbines; Period of Performance: October 31, 2002--January 31, 2003
Wind Tunnel Aerodynamic Tests of Six Airfoils for Use on Small Wind Turbinesrepresents the fourth installment in a series of volumes documenting the ongoing work of th University of Illinois at Urbana-Champaign Low-Speed Airfoil Tests Program. This particular volume deals with airfoils that are candidates for use on small wind turbines, which operate at low Reynolds numbers.
Selig, M. S.; McGranahan, B. D.
The Very Large Hadron Collider: The farthest energy frontier
THE VERY LARGE HADRON COLLIDER: THE FARTHEST ENERGY FRONTIERAbstract The Very Large Hadron Collider (or Eloisatron)
Barletta, William A.
Efficient spatial sampling of large geographical tables
Large-scale map visualization systems play an increasingly important role in presenting geographic datasets to end users. Since these datasets can be extremely large, a map rendering system often needs to select a small fraction of the data to visualize ... Keywords: data visualization, geographical databases, indexing, maps, query processing, spatial sampling
Anish Das Sarma; Hongrae Lee; Hector Gonzalez; Jayant Madhavan; Alon Halevy
Monitoring Large Systems Via Statistical Sampling
As the trend in parallel systems scales toward petaflop performance tapped by advances in circuit density and by an increasingly available computational Grid, the development of efficient mechanisms for monitoring large systems becomes imperative. When ... Keywords: Large systems, performance monitoring, statistical sampling
Celso L. Mendes; Daniel A. Reed
Conformal Blocks in the Large D Limit
We derive conformal blocks in an inverse spacetime dimension expansion. In this large D limit, the blocks are naturally written in terms of a new combination of conformal cross-ratios. We comment on the implications for the conformal bootstrap at large D.
A. Liam Fitzpatrick; Jared Kaplan; David Poland
Thermal management in large Bi2212 mesas used for terahertz sources.
We present a thermal analysis of a patterned mesa on a Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (Bi2212) single crystal that is based on tunneling characteristics of the c-axis stack of {approx}800 intrinsic Josephson junctions in the mesa. Despite the large mesa volume (e.g., 40 times 300 times 1.2 mum{sup 3}) and power dissipation that result in self-heating and backbending of the current-voltage curve (I-V), there are accessible bias conditions for which significant polarized THz-wave emission can be observed. We estimate the mesa temperature by equating the quasiparticle resistance, R{sub qp}(T), to the ratio V/I over the entire I-V including the backbending region. These temperatures are used to predict the unpolarized black-body radiation reaching our bolometer and there is substantial agreement over the entire I-V. As such, backbending results from the particular R{sub qp}(T) for Bi2212, as first discussed by Fenton, rather than a significant suppression of the energy gap. This model also correctly predicts the observed disappearance of backbending above {approx}60 K.
Kurter, C.; Gray, K. E.; Zasadzinski, J. F.; Ozyuzer, L.; Koshelev, A. E.; Li, Q.; Yamamoto, T.; Kadowaki, K.; Kwok, W.-K.; Tachiki, M.; Welp, U.; Materials Science Division; Izmir Inst. of Tech.; Illinois Inst. of Tech.; Univ. Tsukuba; Univ. Tokyo
Tunneling of conduction band electrons driven by a laser field in a double quantum dot: An open systems approach
In this paper, we investigate tunneling of conduction band electrons in a system of an asymmetric double quantum dot which interacts with an environment. First, we consider the case in which the system only interacts with the environment and demonstrate that as time goes to infinity they both reach an equilibrium, which is expected, and there is always a maximum and minimum for the populations of the states of the system. Then we investigate the case in which an external resonant optical pulse (a laser) is applied to the system interacting with the environment. However, in this case for different intensities we have different populations of the states in equilibrium and as the intensity of the laser gets stronger, the populations of the states in equilibrium approach the same constant.
B. Ahmadi; S. Salimi; A. S. Khorashad
Static current-voltage characteristics of Au/CaF{sub 2}/n-Si(111) MIS tunneling structures
Using molecular-beam epitaxy, Au/CaF{sub 2}/n-Si(111) structures were fabricated that exhibit lower currents at a given fluoride film thickness (1.5-2 nm) than those of all similar structures studied. At a positive voltage at the metal, the current is in agreement with that calculated within the model with conservation of the transverse component of the wave vector during tunneling transport. Relative contributions of electron and hole components were analyzed for forward and reverse biases. The effect of the nonuniform distribution of the insulator thickness over the area on measured currents was estimated. The thin CaF{sub 2} layers that were grown are potentially applicable as barrier layers in various devices of functional electronics.
Suturin, S. M., E-mail: firstname.lastname@example.com; Banshchikov, A. G.; Sokolov, N. S.; Tyaginov, S. E.; Vexler, M. I. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)
GaSb/GaAs quantum dot formation and demolition studied with cross-sectional scanning tunneling microscopy
We present a cross-sectional scanning tunneling microscopy study of GaSb/GaAs quantum dots grown by molecular beam epitaxy. Various nanostructures are observed as a function of the growth parameters. During growth, relaxation of the high local strain fields of the nanostructures plays an important role in their formation. Pyramidal dots with a high Sb content are often accompanied by threading dislocations above them. GaSb ring formation is favored by the use of a thin GaAs first cap layer and a high growth temperature of the second cap layer. At these capping conditions, strain-driven Sb diffusion combined with As/Sb exchange and Sb segregation remove the center of a nanostructure, creating a ring. Clusters of GaSb without a well defined morphology also appear regularly, often with a highly inhomogeneous structure which is sometimes divided up in fragments.
Smakman, E. P.; Garleff, J. K.; Rambabu, P.; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ (Netherlands); Young, R. J.; Hayne, M. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)
Scanning tunneling microscopy studies of the surfaces of a-Si:H and a-SiGe:H films
The report contains a detailed description of the experimental complexities encountered in developing scanning tunneling microscope (STM) probing of atomic structure on the surface of freshly-grown hydrogenated-amorphous semiconductors. It also contains a speculative microscopic film-growth model that explains differences between the disorder in CVD grown a-Ge:H versus a-Si:H films. This model is derived from prior results obtained in the chemical analysis of GeH{sub 4} plasmas, combined with surface reaction and thermodynamic considerations. The neutral radical fragments of silane, disilane and germane dissociation in discharges, which dominate the vapor and film-growth reactions, have been deduced from detailed analysis of prior data and are reported. 4 refs., 7 figs.
Gallagher, A.; Ostrom, R.; Tannenbaum, D. (National Inst. of Standards and Technology, Boulder, CO (USA))
Transformation-optics generalization of tunnelling effects in bi-layers made of paired epsilon-negative/mu-negative media
Transformation-media designed by standard transformation-optics (TO) approaches, based on real-valued coordinate-mapping, cannot exhibit single-negative (SNG) character unless such character is already possessed by the domain that is being transformed. In this paper, we show that SNG transformation media can be obtained by transforming a domain featuring double positive (or double-negative) character, via complex analytic continuation of the coordinate transformation rules. Moreover, we apply this concept to the TO-based interpretation of phenomena analogous to the tunnelling effects observable in bilayers made of complementary epsilon-negative (ENG) and mu-negative (MNG) media, and explore their possible TO-inspired extensions and generalizations.
Castaldi, Giuseppe; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader
Initial Recognition of a Cellodextrin Chain in the Cellulose-Binding Tunnel May Affect Cellobiohydrolase Directional Specificity
Initial Initial Recognition of a Cellodextrin Chain in the Cellulose-Binding Tunnel May Affect Cellobiohydrolase Directional Specificity Pavan K. GhattyVenkataKrishna, †‡ Emal M. Alekozai, §{ Gregg T. Beckham, k ** Roland Schulz, {‡‡ Michael F. Crowley, ‡†† * Edward C. Uberbacher, †‡ * and Xiaolin Cheng ‡{‡‡ * † Computational Biology and Bioinformatics Group and ‡ BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; § Interdisciplinary Center for Scientific Computing, University of Heidelberg, Heidelberg Germany; { UT/ORNL Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, Tennessee; k National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado; **Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado; †† Biosciences Center, National
Mining methods used in the underground tunnels and test rooms at Stripa
Results of the Swedish-American cooperative research program are reported in which the cooperating scientists explore the geological, geophysical, hydrological, geochemical, and structural effects anticipated from the use of a large crystalline rock mass as a geologic repository for nuclear waste. Two new methods, smooth blasting and slot drilling, were tested and used at Stripa. The smooth blasting technique uses the symmetric pattern of the contour holes and a low charge density in each round, which results in a uniform and minimal damage to the roof and walls of the excavated cavern and limits the number of newly opened fractures. The length of freshly opened fractures in meters is equal to the charge in kilograms per meter. The slot drilling technique uses an array of small-diameter peripheral percussion-drilled holes to drill ultra-large cores 1 meter in diameter and larger. Both techniques described have been successfully tested and their further use in future excavations of large storage caverns is recommended.
Andersson, B.; Halen, P.A.
Focusing, Power Tunneling and Rejection from Chiral and/or Chiral Nihility/Nihility Metamaterials Layers
Focusing of electromagnetic plane wave from a large size paraboloidal reflector, composed of layers of chiral and/or chiral nihility metamaterials, has been studied us- ing Maslov's method. First, the transmission and reflection of electromagnetic plane wave from two parallel layers of chiral and/or chiral nihility metamaterials are cal- culated using transfer matrix method. The effects of change of angle of incidence, chirality parameters and impedances of layers are noted and discussed. Special cases by taking very large and small values of permittivity of second layer, while assuming value of corresponding chirality equal to zero, are also treated. These special cases are equivalent to reflection from a perfect electric conductor backed chiral layer and nihility backed chiral layer, respectively. Results of reflection from parallel layers have been utilized to study focusing from a large size paraboloidal reflector. The present study, on focusing from a paraboloidal re{\\deg}ector, not only unifies several published works conducted by different researchers but also provides better understanding of new cases.
Syed Touseef Hussain Shah; Faiz Ahmad; Aqeel A. Syed; Qaisar Abbas Naqvi
Large Energy Users Program | Department of Energy
Large Energy Users Program Large Energy Users Program Large Energy Users Program < Back Eligibility Commercial Fed. Government Industrial Institutional Local Government Nonprofit Schools State Government Savings Category Heating & Cooling Commercial Heating & Cooling Heating Cooling Home Weatherization Construction Commercial Weatherization Design & Remodeling Manufacturing Other Appliances & Electronics Heat Pumps Commercial Lighting Lighting Water Heating Maximum Rebate Prescriptive: Varies by equipment type Custom: $200,000 or 30% per project Total Prescriptive and Custom combined: $400,000 per calendar year Program Info Funding Source Focus On Energy Start Date 04/01/2012 Expiration Date 12/31/2013 State Wisconsin Program Type State Rebate Program Rebate Amount Prescriptive: Varies by equipment type
Very Large System Dynamics Models - Lessons Learned
This paper provides lessons learned from developing several large system dynamics (SD) models. System dynamics modeling practice emphasize the need to keep models small so that they are manageable and understandable. This practice is generally reasonable and prudent; however, there are times that large SD models are necessary. This paper outlines two large SD projects that were done at two Department of Energy National Laboratories, the Idaho National Laboratory and Sandia National Laboratories. This paper summarizes the models and then discusses some of the valuable lessons learned during these two modeling efforts.
Jacob J. Jacobson; Leonard Malczynski
Nanophosphors for Large Area Radiation Detectors
Homeland Security & Defense » Homeland Security & Defense » Nanophosphors for Large Area Radiation Detectors Nanophosphors for Large Area Radiation Detectors The present invention includes a composition comprising nanophosphor particles capped with a ligand. June 25, 2013 Nanophosphors for Large Area Radiation Detectors The present invention includes a composition comprising nanophosphor particles capped with a ligand. Available for thumbnail of Feynman Center (505) 665-9090 Email Nanophosphors for Large Area Radiation Detectors The present invention includes a composition comprising nanophosphor particles capped with a ligand. The nanophosphor particles have are less than or equal to 20 nanometers. The composition has at least one lanthanide and at least one halide. The weight percent of lanthanide
These plants are more than 30 MW in size, and there is more than 80,000 MW of installed generation capacity in the United States today. Most large-scale hydropower projects use a...
Decontamination of large components-test case
The rising per-cubic-foot burial costs, together with the trend toward standardized above-ground burial sites, provides the basis for seeking an alternative to direct burial of large components. Large contaminated components such as steam generators can be safely dismantled and decontaminated for free release, metals recycle, and volume reduction. This grand-scale disposal technology will prove to be an economical and ecological alternative to direct burial or interim storage. Yankee Atomic Electric Company (YAEC) in Bolton, operators and decommissioners of the Yankee Nuclear Power Station in Rowe, Massachusetts, has teamed with Frank W Hake Associates in Memphis, TN, to decontaminate a large component as a test case. The large component is YAEC`s reactor pressure vessel head (RPVH). The 79 100 lb RPVH is surface contaminated with 0.7 Ci (1500 mR/h contact) resulting from 32 yr of operating in a 2000 psi, 530{degrees}F pressurized water reactor environment.
Mancini, A. [Yankee Atomic Electric Co., Bolton, MA (United States); Bosco, B. [Frank W. Hake Associates, Memphis, TN (United States)
Early Cloud Formation by Large Area Fires
Fires simultaneously burning in hundreds of square kilometers could result from a nuclear weapon explosion. The strong buoyancy field of such large area fires induces high-velocity fire winds that turn upward in the burning region. This results ...
R. D. Small; K. E. Heikes
Large-Eddy Boundary Layer Entrainment
A series of large-eddy simulations have been performed to explore boundary layer entrainment under conditions of a strongly capped inversion layer with the boundary layer dynamics driven dominantly by buoyant forcing. Different conditions ...
D. C. Lewellen; W. S. Lewellen
Large-Scale Hydrogen Combustion Experiments
Large-scale combustion experiments show that deliberate ignition can limit hydrogen accumulation in reactor containments. The collected data allow accurate evaluation of containment pressures and temperatures associated with hydrogen combustion.
Large-Scale Dynamics and Global Warming
Predictions of future climate change raise a variety of issues in large-scale atmospheric and oceanic dynamics. Several of these are reviewed in this essay, including the sensitivity of the circulation of the Atlantic Ocean to increasing ...
Isaac M. Held
Aircraft Icing Caused by Large Supercooled Droplets
The characteristic of aircraft icing environments containing large supercooled droplets are described. Substantial loss in rate of climb capability can result from less than 10 minutes duration in conditions where fewer than 0.1�1 cm?3 of ...
Marcia K. Politovich
Large-Scale Offshore Wind Power
Large-Scale Offshore Wind Power in the United States EXECUTIVE SUMMARY September 2010 NOTICE This report was prepared as an account of work sponsored by an agency of the United...
Large-Eddy Simulation of Contrails
Numerical simulations of contrails have been performed to investigate the role of various external parameters and physical processes in the life cycle of contrails. The general idea underlying the model is that of a large-eddy model. The model ...
Andreas Chlond
Fermilab Now - LHC Large Hadron Collider
Large Hadron Collider (LHC) Over the next few months, a 12,500-ton detector will be lowered almost 300 feet below ground near the French-Swiss border. Dubbed "CMS," this detector...
California Initiative for Large Molecule Sustainable Fuels
California Initiative for Large Molecule Sustainable Fuels Transportation Energy Research PIER these fuels stands in the way of California's energy independence. Liquid fuels produced from biomass have California's preeminence in this field of technology, creating green jobs through these technologies
Occlusion Culling in Large Virtual Environments
In this paper, occlusion testing in very large virtual environments is discussed from two perspectives: a theoretical one, discussing occlusion culling in relation to detail elision (level of detail), and a practical one, relating to an adaptive occlusion-culling ...
Karsten Bormann
Program Management for Large Scale Engineering Programs
The goal of this whitepaper is to summarize the LAI research that applies to program management. The context of most of the research discussed in this whitepaper are large-scale engineering programs, particularly in the ...
Oehmen, Josef
Very Large Hailstones From Aurora, Nebraska
The Aurora, Nebraska, hailstorm of 22 June 2003 produced some exceptionally large hailstones, and was widely publicized. Nineteen hailstones obtained from local people have been sectioned and photographed and eight are illustrated here, recording ...
Charles A. Knight; Nancy C. Knight
Large Wind Technology | Department of Energy
Large Wind Technology Large Wind Technology Large Wind Technology The Wind Program works with industry partners to increase the performance and reliability of large wind technologies while lowering the cost of wind energy. The program's research efforts have helped to increase the average capacity factor (a measure of power plant productivity) from 22% for wind turbines installed before 1998 to 35% for turbines installed between 2004 and 2007. Wind energy costs have been reduced from over 55 cents (current dollars) per kilowatt-hour (kWh) in 1980 to under six cents/kWh today. To ensure future industry growth, the technology must continue to evolve, building on earlier successes to further improve reliability, increase capacity factors, and reduce costs. This page describes the goal of the
Trojan PWR Decommissioning: Large Component Removal Project
While the decommissioning of large commercial nuclear plants in the United States is in its infancy, the technical challenges with associated radioactive waste management are clear. This report describes the removal and disposal of four steam generators and one pressurizer from the Trojan nuclear power plant, the first large PWR to be decommissioned in the United States. The report chronicles the problems, successes, and lessons learned in this project, which was completed on schedule and under budget in...
3D Technologies for Large Area Trackers
We describe technologies which can be developed to produce large area, low cost pixelated tracking detec- tors. These utilize wafer-scale 3D electronics and sensor technologies currently being developed in industry. This can result in fully active sensor/readout chip tiles which can be assembled into large area arrays with good yield and minimal dead area. The ability to connect though the bulk of the device can also provide better electrical performance and lower mass.
Deptuch, G; Johnson, M; Kenney, C; Lipton, R; Narian, M; Parker, S; Shenai, A; Spiegel, L; Thom, J; Ye, Z
G. Deptuch; U. Heintz; M. Johnson; C. Kenney; R. Lipton; M. Narian; S. Parker; A. Shenai; L. Spiegel; J. Thom; Z. Ye
Property:Length(m) | Open Energy Information
Length(m) Length(m) Jump to: navigation, search This is a property of type String, and provides a complied list of the lengths of various hydrodynamic testing facilities. Pages using the property "Length(m)" Showing 25 pages using this property. (previous 25) (next 25) 1 1.5-ft Wave Flume Facility + 45.1 + 10-ft Wave Flume Facility + 63.4 + 11-ft Wave Flume Facility + 77.4 + 2 2-ft Flume Facility + 61.0 + 3 3-ft Wave Flume Facility + 45.1 + 5 5-ft Wave Flume Facility + 63.4 + 6 6-ft Wave Flume Facility + 105.2 + A Alden Large Flume + 24.4 + Alden Small Flume + 17.1 + Alden Tow Tank + 30.5 + Alden Wave Basin + 33.5 + B Breakwater Research Facility + 121.9 + Bucknell Hydraulic Flume + 9.8 + C Carderock Circulating Water Channel + 18.3 + Carderock Large Cavitation Tunnel + 13.1 +
Property:Bandwidth(kHz) | Open Energy Information
Bandwidth(kHz) Bandwidth(kHz) Jump to: navigation, search Property Name Bandwidth(KHz) Property Type String Pages using the property "Bandwidth(kHz)" Showing 25 pages using this property. (previous 25) (next 25) C Conte Large Flume + 44 + Conte Small Flume + 44 + D Davidson Laboratory Tow Tank + .025 typical; can measure at higher frequencies if needed + DeFrees Flume 1 + 1000 + DeFrees Flume 2 + 1000 + DeFrees Flume 4 + 1000 + DeFrees Large Wave Basin + 1000 + DeFrees Small Wave Basin + 1000 + H Hinsdale Wave Basin 1 + Up to 1 MS/s + Hinsdale Wave Basin 2 + Up to 1 MS/s + M MHL 2D Wind/Wave + 20 + MHL Free Surface Channel + 20 + MHL High Speed Cavitation + 20 + MHL Student Tunnel + 20 + MHL Tow Tank + 20 + MIT Tow Tank + +/- 10V + Maine Tow Tank + 10 +
Table 8: Water Consumption Information for Large Hospitals
U.S. Energy Information Administration (EIA)
Water Consumption Information for Large Hospitals, 2007 Table H8. RSEs for Water Consumption Information for Large Hospitals, 2007 Number of Large Hospital Buildings
Large hadron collider (LHC) project quality assurance plan
PUB-5478-Rev.B Large Hadron Collider (LHC) Project Qualityobjectives of the Large Hadron Collider (LHC) Project in aparticipation in the Large Hadron Collider Project. The LHC/
Gullo, Lisa; Karpenko, Victor; Robinson, Kem; Turner, William; Wong, Otis
The Control System for the Cryogenics in the LHC Tunnel [First Experience and Improvements
The Large Hadron Collider (LHC) was commissioned at CERN and started operation with beams in 2008. Several months of operation in nominal cryogenic conditions have triggered an optimisation of the process functional analysis. This lead to a few revisions of the control logic, which were realised on-the-fly. During the 2008-09 shut-down, and in order to enhance the safety, availability and operability of the LHC cryogenics, a major rebuild of the logic and several hardware modifications were implemented. The databases, containing instruments and controls in-formation, are being rationalized; the automatic tool, that extracts data for the control software, is being simplified. This paper describes the main improvements and sug-gests perspectives of further developments.
Gomes, P; Casas, J; Fluder, C; Fortescue, E; Le Roux, P; Penacoba, G; Pezzetti, M; Soubiran, M; Tovar, A; Zwalinski, L
2007 CBECS Large Hospital Building List of Tables
Annual Energy Outlook 2012 (EIA)
End Uses in Large Hospitals Table H3: End Use Equipment in Large Hospitals Table H4: Lighting and Window Features in Large Hospitals Table H5: Major Fuels Usage for Large...
Category:LargeOffice | Open Energy Information
LargeOffice LargeOffice Jump to: navigation, search Go Back to PV Economics By Building Type Media in category "LargeOffice" The following 77 files are in this category, out of 77 total. SVLargeOffice Bismarck ND Montana-Dakota Utilities Co (North Dakota).png SVLargeOffice Bismarck... 69 KB SVLargeOffice Cedar City UT Moon Lake Electric Assn Inc (Utah).png SVLargeOffice Cedar Ci... 57 KB SVLargeOffice International Falls MN Northern States Power Co (Minnesota) Excel Energy.png SVLargeOffice Internat... 83 KB SVLargeOffice LA CA City of Los Angeles California (Utility Company).png SVLargeOffice LA CA Ci... 92 KB SVLargeOffice Memphis TN City of Memphis Tennessee (Utility Company).png SVLargeOffice Memphis ... 70 KB SVLargeOffice Minneapolis MN Northern States Power Co (Minnesota) Excel Energy.png
Stimulated Raman scattering in large plasmas
Stimulated Raman scattering is of concern to laser fusion since it can create a hot electron environment which can increase the difficulty of achieving high final fuel densities. In earlier experiments with one micron laser light, the energy measured in Raman-scattered light has been insignificant. But these experiments were done with, at most, about 100 joules of laser energy. The Raman instability has a high threshold which also requires a large plasma to be irradiated with a large diameter spot. Only with a long interaction length can the Raman-scattered light wave convectively grow to a large amplitude, and only in recent long pulse, high energy experiments (4000 joules in 2 ns) at the Shiva laser facility have we observed as much as several percent of the laser light to be Raman-scattered. We find that the Raman instability has a much lower intensity threshold for longer laser pulselength and larger laser spot size on a solid target.
Phillion, D.W.; Banner, D.L.
Category:LargeHotel | Open Energy Information
LargeHotel LargeHotel Jump to: navigation, search Go Back to PV Economics By Building Type Media in category "LargeHotel" The following 77 files are in this category, out of 77 total. SVLargeHotel Bismarck ND Montana-Dakota Utilities Co (North Dakota).png SVLargeHotel Bismarck ... 70 KB SVLargeHotel International Falls MN Northern States Power Co (Minnesota) Excel Energy.png SVLargeHotel Internati... 85 KB SVLargeHotel LA CA City of Los Angeles California (Utility Company).png SVLargeHotel LA CA Cit... 88 KB SVLargeHotel Memphis TN City of Memphis Tennessee (Utility Company).png SVLargeHotel Memphis T... 67 KB SVLargeHotel Minneapolis MN Northern States Power Co (Minnesota) Excel Energy.png SVLargeHotel Minneapol... 85 KB SVLargeHotel Minot ND Montana-Dakota Utilities Co (North Dakota).png
BNL | Large Synoptic Survey Telescope (LSST)
Large Synoptic Survey Telescope Large Synoptic Survey Telescope About LSST Digital Sensor Array Brookhaven & Physics of the Universe LSST Project Website LSST: Providing an Unprecedented View of the Cosmos rendering of the LSST site in Chile A revolutionary 3.2 gigapixel camera mounted in a massive ground-based telescope will produce unprecedented views of the cosmos, driving discoveries with the widest, densest, and most complete images of our universe ever captured. New Visions The Large Synoptic Survey Telescope (LSST) will peer into space as no other telescope can. This new facility will create an unparalleled wide-field astronomical survey of our universe - wider and deeper in volume than all previous telescopes combined. The combination of a 3200 megapixel camera sensor array, a powerful supercomputer, a cutting-edge data processing and
Optimization of the configuration of a symmetric three-barrier resonant-tunneling structure as an active element of a quantum cascade detector
On the basis of a model of rectangular potentials and different electron effective masses in wells and barriers of an open resonant-tunneling structure with identical outer barriers, a theory has been developed and the dynamic conductance caused by the interaction of the electromagnetic field with electrons passing through the structure has been calculated. Using the example of the three-barrier resonant-tunneling structure with In{sub 0.53}Ga{sub 0.47}As wells and In{sub 0.52}Al{sub 0.48}As barriers, it is shown that, independently of the geometrical sizes of potential wells and barriers, there exist three geometrical configurations (positions of the inner barrier with respect to outer ones) at which the nanosystem, as an active element, provides optimum operating conditions of the quantum cascade detector.
Tkach, N. V., E-mail: email@example.com; Seti, Ju. A. [Fedkovich Chernivtsy National University (Ukraine)
Large volume flow-through scintillating detector
A large volume flow through radiation detector for use in large air flow situations such as incinerator stacks or building air systems comprises a plurality of flat plates made of a scintillating material arranged parallel to the air flow. Each scintillating plate has a light guide attached which transfers light generated inside the scintillating plate to an associated photomultiplier tube. The output of the photomultiplier tubes are connected to electronics which can record any radiation and provide an alarm if appropriate for the application.
Gritzo, Russ E. (Los Alamos, NM); Fowler, Malcolm M. (Los Alamos, NM)
Process Energy Audit for Large Industries
This paper discusses the author's approach to energy audits of large industries. Five large industrial segments, with energy intensive processes have been selected as examples. Items include: 1) the general methodology of conducting comprehensive industrial energy audit, 2) how one can identify energy efficiency opportunities, and 3) illustrate a few case study examples of energy conservation measures implemented in some of the industries, and 4) the importance of quality assurance/quality control in an energy audit. I will restrict this discussion to only electrical energy audit.
Chari, S.
Defect assistant band alignment transition from staggered to broken gap in mixed As/Sb tunnel field effect transistor heterostructure
The compositional dependence of effective tunneling barrier height (E{sub beff}) and defect assisted band alignment transition from staggered gap to broken gap in GaAsSb/InGaAs n-channel tunnel field effect transistor (TFET) structures were demonstrated by x-ray photoelectron spectroscopy (XPS). High-resolution x-ray diffraction measurements revealed that the active layers are internally lattice matched. The evolution of defect properties was evaluated using cross-sectional transmission electron microscopy. The defect density at the source/channel heterointerface was controlled by changing the interface properties during growth. By increasing indium (In) and antimony (Sb) alloy compositions from 65% to 70% in In{sub x}Ga{sub 1-x}As and 60% to 65% in GaAs{sub 1-y}Sb{sub y} layers, the E{sub beff} was reduced from 0.30 eV to 0.21 eV, respectively, with the low defect density at the source/channel heterointerface. The transfer characteristics of the fabricated TFET device with an E{sub beff} of 0.21 eV show 2 Multiplication-Sign improvement in ON-state current compared to the device with E{sub beff} of 0.30 eV. On contrary, the value of E{sub beff} was decreased from 0.21 eV to -0.03 eV due to the presence of high defect density at the GaAs{sub 0.35}Sb{sub 0.65}/In{sub 0.7}Ga{sub 0.3}As heterointerface. As a result, the band alignment was converted from staggered gap to broken gap, which leads to 4 orders of magnitude increase in OFF-state leakage current. Therefore, a high quality source/channel interface with a properly selected E{sub beff} and well maintained low defect density is necessary to obtain both high ON-state current and low OFF-state leakage in a mixed As/Sb TFET structure for high-performance and lower-power logic applications.
Zhu, Y.; Jain, N.; Vijayaraghavan, S.; Hudait, M. K. [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Mohata, D. K.; Datta, S. [Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania-16802 (United States); Lubyshev, D.; Fastenau, J. M.; Liu, Amy K. [IQE Inc., Bethlehem, Pennsylvania-18015 (United States); Monsegue, N. [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)
Structure of Au on Ag(110) studied by scanning tunneling microscopy S. Chiang, S. Rousset,a) D. E. Fowler, and D. D. Chambliss
Structure of Au on Ag(110) studied by scanning tunneling microscopy S. Chiang, S. Rousset,a) D. E/12(3)/1747/4/$1.00 @1994 American Vacuum Society 1747 #12;1748 Chiang et 81.: Structure of Au on Ag(110) studied by STM Fll 10 min apart; #12;1749 Chiang et al.: Structure of Au on Ag(110) studied by STM FIG. 3. (a) -2 ML Au
Chiang, Shirley
Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope
A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p {<=}10{sup -10} mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.
Hagedorn, Till; Ouali, Mehdi El; Paul, William; Oliver, David; Miyahara, Yoichi; Gruetter, Peter [Department of Physics, McGill University, 3600 Rue University, Montreal, QC H3A2T8 (Canada)
Structural properties of the graphene-SiC(0001) interface as a key for the preparation of homogeneous large-terrace graphene surfaces
We report on the interface between graphene and 4H-SiC(0001) as investigated by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). It is characterized by the so-called (6{radical}(3)x6{radical}(3))R30 deg. reconstruction, whose structural properties are still controversially discussed but at the same time are crucial for the controlled growth of homogeneous high-quality large-terrace graphene surfaces. We discuss the role of three observed phases with periodicities (6{radical}(3)x6{radical}(3))R30 deg. (6x6), and (5x5). Their LEED intensity levels and spectra strongly depend on the surface preparation procedure applied. The graphitization process imprints distinct features in the STM images as well as in the LEED spectra. The latter have the potential for an easy and practicable determination of the number of graphene layers by means of LEED.
Riedl, C.; Starke, U.; Bernhardt, J.; Franke, M.; Heinz, K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Lehrstuhl fuer Festkoerperphysik, Universitaet Erlangen-Nuernberg, Staudtstrasse 7, D-91058 Erlangen (Germany)
Growth sequence and interface formation in the Fe/MgO/Fe(001) tunnel junction analyzed by surface x-ray diffraction
We present a surface x-ray diffraction study of the interface geometric structure in the Fe/MgO/Fe(001) magnetic tunnel junction (MTJ). While the lower MgO/Fe(001) interface is characterized by a substoichiometric FeO{sub x} (x=0.6{+-}0.1) layer in agreement with previous studies, growth of Fe on the MgO spacer and the upper Fe/MgO interface structure strongly depends on the preparation method. If 0.4 monolayers of Fe are initially deposited in ambient oxygen atmosphere (p=10{sup -7} mbar) followed by Fe deposition under ultrahigh-vacuum (UHV) conditions, structural coherence across the trilayer junction is observed. In this case, substoichiometric FeO{sub x} layers are present at both Fe/MgO interfaces corresponding to a symmetric MTJ structure. In contrast, lattice registry is not preserved if Fe deposition is carried out solely under UHV conditions. Our results might have important implications for the preparation of magnetic tunnel junctions optimized to achieve giant tunneling-magnetoresistance amplitudes.
Tusche, C.; Meyerheim, H. L.; Kirschner, J. [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany); Jedrecy, N. [Institut des NanoSciences de Paris, Universites Paris 6 et 7 et CNRS-UMR 7588, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Renaud, G. [CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble (France)
Scaling Issues for Large-Scale Grids
· ESNet Can Play a Very Important Role in the Science Grid �? Security Aspects of Grids · ESNet Can Provide will be important and very useful for managing large-scale virtual org. structures #12;·ESNet Can Play a Very Important Role in the Science Grid · ESNet can provide a rooted and managed namespace, and a place to home
Intelligent Power Management Over Large Clusters
There is a growing tension within large organisations such as universities between the desire to perform vast amounts of computational processing and the desire to reduce power consumption by switching off computers. This situation will only worsen as ... Keywords: power management, condor, green computing
A. Stephen McGough; Clive Gerrard; Paul Haldane; Dave Sharples; Dan Swan; Paul Robinson; Sindre Hamlander; Stuart Wheater
Gravitating Dyons with Large Electric Charge
We consider non-Abelian dyons in Einstein-Yang-Mills-Higgs theory. The dyons are spherically symmetric with unit magnetic charge. For large values of the electric charge the dyons approach limiting solutions, related to the Penney solutions of Einstein-Maxwell-scalar theory.
Rustam Ibadov; Burkhard Kleihaus; Jutta Kunz; Ulrike Neemann
Distributed large-scale natural graph factorization
Natural graphs, such as social networks, email graphs, or instant messaging patterns, have become pervasive through the internet. These graphs are massive, often containing hundreds of millions of nodes and billions of edges. While some theoretical models ... Keywords: asynchronous algorithms, distributed optimization, graph algorithms, graph factorization, large-scale machine learning, matrix factorization
Amr Ahmed, Nino Shervashidze, Shravan Narayanamurthy, Vanja Josifovski, Alexander J. Smola
Data editing on large data sets
The process of analyzing large data sets often includes an early exploratory stage to first, develop a basic understanding of the data and its interrelationships and second, to prepare and cleanup the data for hypothesis formulation and testing. This preliminary phase of the data analysis process usually requires facilities found in research data management systems, text editors, graphics packages, and statistics packages. Also this process usually requires the analyst to write special programs to cleanup and prepare the data for analysis. This paper describes a technique now implemented as a single computational tool, a data editor, which combines a cross section of facilities from the above systems with emphasis on research data base manipulation and subsetting techniques. The data editor provides an interactive environment to explore and manipulate data sets with particular attention to the implications of large data sets. It utilizes a relational data model and a self describing binary data format which allows data transportability to other data analysis packages. Some impacts of editing large data sets will be discussed. A technique for manipulating portions or subsets of large data sets without physical replication is introduced. Also an experimental command structure and operating environment are presented.
Thomas, J.J.; Burnett, R.A.; Lewis, J.R.
Large Lenses of Highly Saline Mediterranean Water
Isolated compact anticyclonic eddies or salt lenses were found in the Canary Basin. Hydrographic surveys of three such lenses show large anomalies of salinity and temperature (0.8, 2.5�C). They are centered at 1100 m, have a vertical extent of ...
Laurence Armi; Walter Zenk
Modeling needs for very large systems.
Most system performance models assume a point measurement for irradiance and that, except for the impact of shading from nearby obstacles, incident irradiance is uniform across the array. Module temperature is also assumed to be uniform across the array. For small arrays and hourly-averaged simulations, this may be a reasonable assumption. Stein is conducting research to characterize variability in large systems and to develop models that can better accommodate large system factors. In large, multi-MW arrays, passing clouds may block sunlight from a portion of the array but never affect another portion. Figure 22 shows that two irradiance measurements at opposite ends of a multi-MW PV plant appear to have similar irradiance (left), but in fact the irradiance is not always the same (right). Module temperature may also vary across the array, with modules on the edges being cooler because they have greater wind exposure. Large arrays will also have long wire runs and will be subject to associated losses. Soiling patterns may also vary, with modules closer to the source of soiling, such as an agricultural field, receiving more dust load. One of the primary concerns associated with this effort is how to work with integrators to gain access to better and more comprehensive data for model development and validation.
Stein, Joshua S.
Reuse and variability in large software applications
Reuse has always been a major goal in software engineering, since it promises large gains in productivity, quality and time to market reduction. Practical experience has shown that substantial reuse has only successfully happened in two cases: libraries, ... Keywords: AOP, COTS, EAI, MDA, interoperability, model driven software engineering, process driven application, product families, product line, reuse, variability, workflow
Jacky Estublier; German Vega
Modifying the molecular dynamics action to increase topological tunnelling rate for dynamical overlap fermions
We describe a new Hybrid Monte Carlo (HMC) algorithm for dynamical overlap fermions, which improves the rate of topological index changes by adding an additional (intensive) term to the action for the molecular dynamics part of the algorithm. The metropolis step still uses the exact action, so that the Monte Carlo algorithm still generates the correct ensemble. By tuning this new term, we hope to be able to balance the acceptance rate of the HMC algorithm and the rate of topological index changes. We also describe how suppressing, but not eliminating, the small eigenvalues of the kernel operator may improve the volume scaling of the cost per trajectory for overlap HMC while still allowing topological index changes. We test this operator on small lattices, comparing our new algorithm with an old overlap HMC algorithm with a slower rate of topological charge changes, and an overlap HMC algorithm which fixes the topology. Our new HMC algorithm more than doubles the rate of topological index changes compared to the previous state of the art, while maintaining the same metropolis acceptance rate. We investigate the effect of topological index changes on the local topological charge density, measured using an improved field theoretic operator after heavy smearing. We find that the creation and annihilation of large lumps of topological charge is increased with the new algorithm.
Nigel Cundy; Weonjong Lee
A Measurement System for Systematic Hydrological Characterization of Unsaturated Fractured Welded Tuff in a Mined Underground Tunnel
A field investigation of unsaturated flow through a lithophysal unit of fractured welded tuff containing lithophysal cavities has been initiated. To characterize flow in this spatially heterogeneous medium, a systematic approach has been developed to perform tests in boreholes drilled at regular intervals in an underground tunnel (drift). In this paper, we describe the test equipment system that has been built for this purpose. Since the field-scale measurements, of liquid flow in the unsaturated, fractured rocks, require continuous testing for periods of days to weeks, the control of test equipment has been fully automated, allowing operation with no human presence at the field site. Preliminary results from the first set of tests are described. These tests give insight into the role of the matrix (perhaps also lithophysal cavities) as potential storage during the initial transient flow prior to the breakthrough of water at the drift crown, as well as the role of connected fractures that provide the subsequent quasi-steady flow. These tests also reveal the impact of evaporation on seepage into the drift.
R. J. Cook; R. Salve; B.M. Freifeld; Y.W. Tsang
Process For Direct Integration Of A Thin-Film Silicon P-N Junction Diode With A Magnetic Tunnel Junction
A process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction for use in advanced magnetic random access memory (MRAM) cells for high performance, non-volatile memory arrays. The process is based on pulsed laser processing for the fabrication of vertical polycrystalline silicon electronic device structures, in particular p-n junction diodes, on films of metals deposited onto low temperature-substrates such as ceramics, dielectrics, glass, or polymers. The process preserves underlayers and structures onto which the devices are typically deposited, such as silicon integrated circuits. The process involves the low temperature deposition of at least one layer of silicon, either in an amorphous or a polycrystalline phase on a metal layer. Dopants may be introduced in the silicon film during or after deposition. The film is then irradiated with short pulse laser energy that is efficiently absorbed in the silicon, which results in the crystallization of the film and simultaneously in the activation of the dopants via ultrafast melting and solidification. The silicon film can be patterned either before or after crystallization.
Toet, Daniel (Mountain View, CA); Sigmon, Thomas W. (Albuquerque, NM)
Corrective Action Decision Document/Closure Report for Corrective Action Unit 383: Area E-Tunnel Sites, Nevada Test Site
This Corrective Action Decision Document/Closure Report (CADD/CR) was prepared by the Defense Threat Reduction Agency (DTRA) for Corrective Action Unit (CAU) 383, Area 12 E-Tunnel Sites, which is the joint responsibility of DTRA and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office (NNSA/NSO). This CADD/CR is consistent with the requirements of the Federal Facility Agreement and Consent Order (FFACO) agreed to by the State of Nevada, the DOE, and the U.S. Department of Defense. Corrective Action Unit 383 is comprised of three Corrective Action Sites (CASs) and two adjacent areas: � CAS 12-06-06, Muckpile � CAS 12-25-02, Oil Spill � CAS 12-28-02, Radioactive Material � Drainage below the Muckpile � Ponds 1, 2, and 3 The purpose of this CADD/CR is to provide justification and documentation to support the recommendation for closure with no further corrective action, by placing use restrictions at the three CASs and two adjacent areas of CAU 383.
Process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction
Contributions to the Workshop on an e+e- collider in the VLHC tunnel
This Workshop was extremely useful in fleshing out many of the details related to the VLLC. For example, at the workshop it became very clear that the large machine could not provide high luminosity polarized beams at both the Z0 pole and at high energy, and it would be best to provide the Z0 factory function in the injector. In addition, the workshop identified a number of topics for further R and D. A list of some of these topics follows: What is the lower limit on {beta}{sub y}* in the high energy collider? What is a reasonable upper limit on the beam-beam parameter at 183 GeV? Is there a way to coalesce electron bunches at high energy to finesse the TMCI current limit at injection, allowing a smaller beam pipe aperture to be used? Can feedback systems be useful to combat the TMCI instability at injection? In the 45 GeV Z{sup 0} factory, are two rings essential? Are wigglers essential for polarization in the Z{sup 0} factory? How can polarization at high energies be optimized? What is the optimum method of pumping the long vacuum chamber sections? How much cost and power minimization is possible in the complete design? What is the cost of the final system? How can the low field magnets be optimized (alloys, lamination shapes, etc.)? How do we get adequate shielding of the beam from the environment? How can we eliminate the Q-slope in superconducting rf cavities using sputtered niobium on copper? It is hoped the VLLC concept will be explored further, and some of these questions will be addressed, at the Snowmass 2001 Workshop.
E Keil et al.
New England Wind Forum: Large Wind
Wind Powering America (EERE)
Small Wind Small Wind Large Wind Newsletter Perspectives Events Quick Links to States CT MA ME NH RI VT Bookmark and Share Large Wind When establishing wind farms, wind energy developers generally approach landowners where they want to build. Interest in wind farms is frequently spurred by external pressures such as tax and other financial incentives and legislative mandates. Since each situation is influenced by local policies and permitting, we can only provide general guidance to help you learn about the process of installing wind turbines. Publications Wind Project Development Process Permitting of Wind Energy Facilities: A Handbook. (August 2002). National Wind Coordinating Collaborative. Landowner Frequently Asked Questions and Answers. (August 2003). "State Wind Working Group Handbook." pp. 130-133.
2007 CBECS Large Hospital Building FAQs
Gasoline and Diesel Fuel Update (EIA)
FAQs Main Report | Methodology | FAQ | FAQs Main Report | Methodology | FAQ | List of Tables CBECS 2007 - Release date: August 17, 2012 How were the data collected for this study? These data were collected with the 2007 Commercial Building Energy Consumption Survey (CBECS). See the 2007 CBECS Large Hospital Building Methodology Report for details. Why are you publishing estimates only for large hospitals and not the rest of the commercial building population? A majority of the 2007 CBECS buildings were sampled from a frame that used a less expensive experimental method to update the 2003 frame for new construction. After careful analysis, EIA determined that the buildings sampled from this experimental frame were not representative of the commercial building population and therefore the 2007 CBECS sample as a
Entanglement Entropy at Large Central Charge
Two-dimensional conformal field theories with a large central charge and a small number of low-dimension operators are studied using the conformal block expansion. A universal formula is derived for the Renyi entropies of N disjoint intervals in the ground state, valid to all orders in a series expansion. This is possible because the full perturbative answer in this regime comes from the exchange of the stress tensor and other descendants of the vacuum state. Therefore, the Renyi entropy is related to the Virasoro vacuum block at large central charge. The entanglement entropy, computed from the Renyi entropy by an analytic continuation, decouples into a sum of single-interval entanglements. This field theory result agrees with the Ryu-Takayanagi formula for the holographic entanglement entropy of a 2d CFT, applied to any number of intervals, and thus can be interpreted as a microscopic calculation of the area of minimal surfaces in 3d gravity.
Hartman, Thomas
Thomas Hartman
Siting technologies for large wind turbine clusters
Site selection for large wind turbine clusters requires thorough documentation of the wind characteristics at the site, because of the influence these characteristics will have on the economics, operations, and service life of the wind turbines. The wind prospecting strategy can be used by a utility to determine specific locations for each wind turbine in a cluster of 10 to 50 or more machines. The key to site selection is knowing what and where to measure. Siting techniques to be used at the various stages of the wind-prospecting strategy are discussed. These techniques help determine where to measure. What to measure at a site is still a moot question. Suggestions are made on what data are needed at what sampling rates. These are based on the assumption that until further experience in siting large clusters of wind turbines is in hand, thorough documentation of wind characteristics affecting machine and cluster output characteristics, operation strategies, and service life are necessary.
Hiester, T.R.; Pennell, W.T.
Big Science and the Large Hadron Collider
The Large Hadron Collider (LHC), the particle accelerator operating at CERN, is probably the most complex and ambitious scientific project ever accomplished by humanity. The sheer size of the enterprise, in terms of financial and human resources, naturally raises the question whether society should support such costly basic-research programs. I address this question here by first reviewing the process that led to the emergence of Big Science and the role of large projects in the development of science and technology. I then compare the methodologies of Small and Big Science, emphasizing their mutual linkage. Finally, after examining the cost of Big Science projects, I highlight several general aspects of their beneficial implications for society.
Gian Francesco Giudice
Passive load control for large wind turbines.
Wind energy research activities at Sandia National Laboratories focus on developing large rotors that are lighter and more cost-effective than those designed with current technologies. Because gravity scales as the cube of the blade length, gravity loads become a constraining design factor for very large blades. Efforts to passively reduce turbulent loading has shown significant potential to reduce blade weight and capture more energy. Research in passive load reduction for wind turbines began at Sandia in the late 1990's and has moved from analytical studies to blade applications. This paper discusses the test results of two Sandia prototype research blades that incorporate load reduction techniques. The TX-100 is a 9-m long blade that induces bend-twist coupling with the use of off-axis carbon in the skin. The STAR blade is a 27-m long blade that induces bend-twist coupling by sweeping the blade in a geometric fashion.
Ashwill, Thomas D.
Large-Scale Renewable Energy Guide
Renewable Energy Guide Renewable Energy Guide Brad Gustafson, FEMP 2 Large-scale RE Guide Large-scale RE Guide: Developing Renewable Energy Projects Larger than 10 MWs at Federal Facilities Introduction and Overview Federal Utility Partnership Working Group May 22, 2013 Federal Energy Management Program Office of Energy Efficiency and Renewable Energy U.S. Department of Energy 3 Federal Energy Management Program FEMP works with key individuals to accomplish energy change within organizations by bringing expertise from all levels of project and policy implementation to enable Federal Agencies to meet energy related goals and to provide energy leadership to the country. 4 FEMP Renewable Energy * Works to increase the proportion of renewable energy in the Federal government's energy mix.
Large Scale Weather Control Using Nuclear Reactors
It is pointed out that controlled release of thermal energy from fission type nuclear reactors can be used to alter weather patterns over significantly large geographical regions. (1) Nuclear heat creates a low pressure region, which can be used to draw moist air from oceans, onto deserts. (2) Creation of low pressure zones over oceans using Nuclear heat can lead to Controlled Cyclone Creation (CCC).(3) Nuclear heat can also be used to melt glaciers and control water flow in rivers.
Moninder Singh Modgil
The promise of the large collider
"In 2007, the most powerful particle accelerator ever built, CERN's new Large hadron Collider, will probe the secrets of matter in the energy states prevailing in the moments after the Big Bang. By colliding particles together when they are moving at close to the speed of ight, physicists hope to find out about matter in its earliest forms, using the energy produced by the collisions." (2 pages)
Higgs Physics at the Large Hadron Collider
A major goal of the future Large Hadron Collider will be the Higgs boson search. In this paper the discovery In this paper the discovery potential is described as a function of the Higgs mass showing that a Standard Model Higgs boson can be discovered after less than two years of running of the collider. The MSSM Higgs searches and the precision achievable on the measurement of the Higgs boson parameters are also discussed.
Davide Costanzo