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Office of Scientific and Technical Information
Mont Vista Capital LLC | Open Energy Information
Open Energy Info (EERE)
Vista Capital LLC Vista Capital LLC Jump to: navigation, search Name Mont Vista Capital LLC Place New York, New York Zip 10167 Sector Services Product Mont Vista Capital is a leading global provider of services to clients in the alternative energy industry. Mont Vista also seeks proprietary trading and growth equity opportunities in alternative energy markets which add value for our stakeholders. References Mont Vista Capital LLC[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Mont Vista Capital LLC is a company located in New York, New York . References ↑ "Mont Vista Capital LLC" Retrieved from "http://en.openei.org/w/index.php?title=Mont_Vista_Capital_LLC&oldid=348916"
Monte Vista Springfield
E-Print Network (OSTI)
for Genetic Resources Preservation Alder Hall Weather Station Monfort Quadrangle Computer Science Vietnam tour.They are located on CSU's Foothills Campus. Solar Plant · A public-private partnership among CSU,000 solar panels. Research Innovation Center (RIC) · Hot-water preheating system at the boiler that allows
Summary of the geology of the San Luis Basin, Colorado-New Mexico with emphasis on the geothermal potential for the Monte Vista Graben. Special Publication 17
DOE Green Energy (OSTI)
The known geologic data of the San Luis Basin are reviewed and related to an understanding of the hydrogeothermal potential of the Alamosa-Monte Vista area. The physiographic setting of the region, the structural framework of the basin, and its influence on the stratigraphic makeup of the rock sequence, which in turn control the occurrence of potential deep water reservoirs, are reviewed. It is suggested that the San Luis Basin was well-developed by Miocene time, and that although the basin was modified by Neogene faulting, it is essentially a late Laramide event having been produced during the Paleogene. Attention is also given to high heat flow along the Rio Grande Rift and to the geothermal gradient of the San Luis Basin. The confined aquifer is then considered in respect to its hydrogeology, water quality, and as to the legal aspects of the system. (LEW)
Burroughs, R.L.
Osage Orange Mulch
NLE Websites -- All DOE Office Websites (Extended Search)
Osage Orange Mulch Name: David Location: NA Country: NA Date: NA Question: Can wood chips from hedge trees (osage orange) be used as mulch in the garden? I know that the wood...
Windows Vista Step by Step Deluxe Edition
Science Conference Proceedings (OSTI)
The smart way to learn Windows Vista one step at a time! Updated with expanded coverage, this deluxe edition covers all of the latest Windows Vista features. You ll discover the smartest ways to stay organized with Windows Mail, Windows Contact, Windows ...
Joyce Cox; Joan Preppernau
Vista and Pemex in LAB deal
SciTech Connect
Vista Chemical (Houston) and Petroleos Mexicanos (Pemex; Mexico City) have firmed up their long-negotiated plans for Pemex to supply feedstock for a linear alkylbenzene (LAB) plant that Vista will build in Mexico (CW, Sept. 16, 1992 p. 8). Specifically, the two companies have signed an agreement of understanding to pursue negotiations and finalize agreements. The plant would cost $250 million, produce 260 million-330 million lbs/year of LAB, and create about 200 permanent jobs. Final agreements, including a site selection, are expected to be completed by midyear. Vista expects startup in 1996, and is considering forming aj oint venture with a Mexican partner.
Morris, G.D.L.
Sandy Vista Regroups and Rebuilds [Participation with a View
Left: Proposed build-out of Sandy Vista neighborhood. Above:rehabili� tated homes in Sandy Vista. 1. New single-familyfund. PLA C ES 1 2 : 2 P1GFORD, WIGHT: SANDY VISTA
Pigford, Richard; Wight, Karen
Comparative Analysis of Genome Sequences with VISTA
DOE Data Explorer (OSTI)
VISTA is a comprehensive suite of programs and databases developed by and hosted at the Genomics Division of Lawrence Berkeley National Laboratory. They provide information and tools designed to facilitate comparative analysis of genomic sequences. Users have two ways to interact with the suite of applications at the VISTA portal. They can submit their own sequences and alignments for analysis (VISTA servers) or examine pre-computed whole-genome alignments of different species. A key menu option is the Enhancer Browser and Database at http://enhancer.lbl.gov/. The VISTA Enhancer Browser is a central resource for experimentally validated human noncoding fragments with gene enhancer activity as assessed in transgenic mice. Most of these noncoding elements were selected for testing based on their extreme conservation with other vertebrates. The results of this enhancer screen are provided through this publicly available website. The browser also features relevant results by external contributors and a large collection of additional genome-wide conserved noncoding elements which are candidate enhancer sequences. The LBL developers invite external groups to submit computational predictions of developmental enhancers. As of 10/19/2009 the database contains information on 1109 in vivo tested elements - 508 elements with enhancer activity.
Dubchak, Inna
Buena Vista Biomass Power LCC | Open Energy Information
Power LCC Jump to: navigation, search Name Buena Vista Biomass Power LCC Place California Sector Biomass Product California-based firm developing and operating an 18MW biomass...
Windows Vista vs Ubuntu Installaci: procs, temps i problemes
Windows Vista vs Ubuntu #12;Índex Instal·lació: procés, temps i problemes Aplicacions Temps d·lació: procés, temps i problemes Procés d'instal·lació de Windows Vista Procés d'instal·lació de Linux Ubuntu 7.04 Temps total Problemes #12;Instal·lació Windows Vista (I) #12;Instal·lació Windows Vista (II
Politècnica de Catalunya, Universitat
Parameter Studies for the VISTA Spacecraft Concept
The baseline design for the VISTA spacecraft concept employs a diode-pumped solid-state laser (DPSSL) driver. This type of driver is now under development at LLNL and elsewhere as an extension of the mature solid-state (glass) laser technology developed for terrestrial applications of inertial confinement fusion (ICF). A DPSSL is repratable up to at least 30 Hz, and has an efficiency soon to be experimentally verified of at least 10%. By using a detailed systems code including the essential physics of a DPSSL, we have run parameter studies for the baseline roundtrip (RT) to Mars with a 100-ton payload. We describe the results of these studies as a function of the optimized (minimum) RT flight duration. We also demonstrate why DT fuel gives the best performance, although DD, D3He, or even antimatter can be used, and why DT-ignited DD is probably the fuel most preferred. We also describe the overall power flow, showing where the fusion energy is ultimately utilized, and estimate the variation in performance to the planets dictated by variations in target gain and other parameters.
Orth, C D
Orange and Rockland Case Study
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
0 2012 0 2012 Orange and Rockland Case Study 1 Voltage Control Device A "Model-Centric" Approach to Smarter Electric Distribution Systems Orange and Rockland Utilities (ORU), is an investor-owned utility and a subsidiary of Consolidated Edison Incorporated (Con Edison), and is located in suburban New York, New Jersey, and Pennsylvania, west of New York City. ORU is a key participant in Con Edison's $272 million Smart Grid Investment Grant (SGIG) project to modernize electric distribution systems. With $136 million in Recovery Act funding from the U.S. Department of Energy, Con Edison and ORU expect to install smart grid technologies that provide: (1) lower frequency and duration of outages, (2)
How Chula Vista, California Is Turning Cooking Oil Into Savings |
How Chula Vista, California Is Turning Cooking Oil Into Savings How Chula Vista, California Is Turning Cooking Oil Into Savings How Chula Vista, California Is Turning Cooking Oil Into Savings January 19, 2011 - 1:21pm Addthis Truck 51 of the Chula Vista Fire Department. Truck 51 of the Chula Vista Fire Department. John Young What does this project do? Reuses cooking oil that is normally considered waste, saving taxpayer dollars. Reduces reliance on foreign oil Cuts emissions Anyone who has ever worked in a restaurant probably shudders at the mention of having to dispose of used cooking oil. While not much can be done to eliminate this unpleasant kitchen task, what's changing is how that oil can be recycled to help reduce our dependence on foreign sources of energy. Used cooking oil is a key (and very low cost) ingredient in the production
Vista International Technologies Inc formerly Nathaniel Energy Corp | Open
Inc formerly Nathaniel Energy Corp Inc formerly Nathaniel Energy Corp Jump to: navigation, search Name Vista International Technologies Inc (formerly Nathaniel Energy Corp) Place Englewood, Colorado Zip 80112 Product Using its proprietary patented technology, the Thermal Gasifier, Nathaniel produces electricity, heat and liquid fuels. References Vista International Technologies Inc (formerly Nathaniel Energy Corp)[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Vista International Technologies Inc (formerly Nathaniel Energy Corp) is a company located in Englewood, Colorado . References ↑ "Vista International Technologies Inc (formerly Nathaniel Energy Corp)" Retrieved from "http://en.openei.org/w/index.php?title=Vista_International_Technologies_Inc_formerly_Nathaniel_Energy_Corp&oldid=352865
Nordic Turbines Inc formerly Vista Dorada Corporation | Open Energy
Inc formerly Vista Dorada Corporation Inc formerly Vista Dorada Corporation Jump to: navigation, search Name Nordic Turbines Inc (formerly Vista Dorada Corporation) Place Centerville, Massachusetts Zip 02632-2933 Sector Wind energy Product Massachusetts-based manufacturer of large scale two-blade wind turbines. Coordinates 45.751935°, -120.902959° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":45.751935,"lon":-120.902959,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Buena Vista Wind Farm I | Open Energy Information
Buena Vista Wind Farm I Buena Vista Wind Farm I Facility Buena Vista Facility Status Decommissioned Owner International Wind Companies Energy Purchaser Pacific Gas & Electric Location Altamont Pass, California Coordinates 37.7347°, -121.652° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.7347,"lon":-121.652,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Multitasking Web Search on Alta Vista Amanda Spink* &
regular search sessions in terms of queries per session and duration, (3) both Excite and Allthe user code assigned by the Alta Vista server Query Terms: terms exactly as entered by the given user. 3 multitasking search sessions were twice longer than regular search sessions in terms of duration and the mean
Jansen, James
Bayou Vista, Texas: Energy Resources | Open Energy Information
Vista, Texas: Energy Resources Vista, Texas: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 29.3263467°, -94.9385339° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":29.3263467,"lon":-94.9385339,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Lake Buena Vista, Florida: Energy Resources | Open Energy Information
Buena Vista, Florida: Energy Resources Buena Vista, Florida: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 28.3936186°, -81.5386842° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":28.3936186,"lon":-81.5386842,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Buena Vista Wind Farm Repower | Open Energy Information
Repower Repower Jump to: navigation, search Name Buena Vista Wind Farm Repower Facility Buena Vista Sector Wind energy Facility Type Commercial Scale Wind Facility Status In Service Owner Babcock & Brown Developer Babcock & Brown Energy Purchaser Pacific Gas & Electric Co Location Altamont Pass CA Coordinates 37.7347°, -121.652° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.7347,"lon":-121.652,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Chula Vista, California: Energy Resources | Open Energy Information
Chula Vista, California: Energy Resources Chula Vista, California: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 32.6400541°, -117.0841955° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":32.6400541,"lon":-117.0841955,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Natural Gas Discovery and Development Impacts on Rio Vista and Its Community
L. , 2004. �The History of Natural Gas in Rio Vista�, River1936, the history making first natural gas well was drilledthe article �The History of the Natural Gas In Rio Vista�,
Gbedema, Tometi Koku
Orange and Rockland Utilities (Gas) - Residential Efficiency Program |
Orange and Rockland Utilities (Gas) - Residential Efficiency Orange and Rockland Utilities (Gas) - Residential Efficiency Program Orange and Rockland Utilities (Gas) - Residential Efficiency Program < Back Eligibility Commercial Industrial Residential Savings Category Heating & Cooling Commercial Heating & Cooling Heating Appliances & Electronics Home Weatherization Commercial Weatherization Sealing Your Home Ventilation Construction Water Heating Program Info State New York Program Type Utility Rebate Program Rebate Amount Furnace: $140 - $420 Water Boiler: $350 or $700 Steam Boiler: $350 Boiler Reset Control: $70 Indirect Water Heater: $210 Programmable Thermostat: $18 Duct and Air Sealing: up to $420 Provider Orange and Rockland Utilities, Inc. Orange and Rockland Utilities provides rebates for residential customers
Experimental Physical Sciences Vistas: MaRIE (draft)
To achieve breakthrough scientific discoveries in the 21st century, a convergence and integration of world-leading experimental facilities and capabilities with theory, modeling, and simulation is necessary. In this issue of Experimental Physical Sciences Vistas, I am excited to present our plans for Los Alamos National Laboratory's future flagship experimental facility, MaRIE (Matter-Radiation Interactions in Extremes). MaRIE is a facility that will provide transformational understanding of matter in extreme conditions required to reduce or resolve key weapons performance uncertainties, develop the materials needed for advanced energy systems, and transform our ability to create materials by design. Our unique role in materials science starting with the Manhattan Project has positioned us well to develop a contemporary materials strategy pushing the frontiers of controlled functionality - the design and tailoring of a material for the unique demands of a specific application. Controlled functionality requires improvement in understanding of the structure and properties of materials in order to synthesize and process materials with unique characteristics. In the nuclear weapons program today, improving data and models to increase confidence in the stockpile can take years from concept to new knowledge. Our goal with MaRIE is to accelerate this process by enhancing predictive capability - the ability to compute a priori the observables of an experiment or test and pertinent confidence intervals using verified and validated simulation tools. It is a science-based approach that includes the use of advanced experimental tools, theoretical models, and multi-physics codes, simultaneously dealing with multiple aspects of physical operation of a system that are needed to develop an increasingly mature predictive capability. This same approach is needed to accelerate improvements to other systems such as nuclear reactors. MaRIE will be valuable to many national security science challenges. Our first issue of Vistas focused on our current national user facilities (the Los Alamos Neutron Science Center [LANSCE], the National High Magnetic Field Laboratory-Pulsed Field Facility, and the Center for Integrated Nanotechnologies) and the vitality they bring to our Laboratory. These facilities are a magnet for students, postdoctoral researchers, and staff members from all over the world. This, in turn, allows us to continue to develop and maintain our strong staff across the relevant disciplines and conduct world-class discovery science. The second issue of Vistas was devoted entirely to the Laboratory's materials strategy - one of the three strategic science thrusts for the Laboratory. This strategy has helped focus our thinking for MaRIE. We believe there is a bright future in cutting-edge experimental materials research, and that a 21st-century facility with unique capability is necessary to fulfill this goal. The Laboratory has spent the last several years defining MaRIE, and this issue of Vistas presents our current vision of that facility. MaRIE will leverage LANSCE and our other user facilities, as well as our internal and external materials community for decades to come, giving Los Alamos a unique competitive advantage, advancing materials science for the Laboratory's missions and attracting and recruiting scientists of international stature. MaRIE will give the international materials research community a suite of tools capable of meeting a broad range of outstanding grand challenges.
Shlachter, Jack [Los Alamos National Laboratory
Population Monte Carlo algorithms
We give a cross-disciplinary survey on ``population'' Monte Carlo algorithms. In these algorithms, a set of ``walkers'' or ``particles'' is used as a representation of a high-dimensional vector. The computation is carried out by a random walk and split/deletion of these objects. The algorithms are developed in various fields in physics and statistical sciences and called by lots of different terms -- ``quantum Monte Carlo'', ``transfer-matrix Monte Carlo'', ``Monte Carlo filter (particle filter)'',``sequential Monte Carlo'' and ``PERM'' etc. Here we discuss them in a coherent framework. We also touch on related algorithms -- genetic algorithms and annealed importance sampling.
Yukito IBA
Energy Efficient Community Development in California: Chula Vista Research Project
In 2007, the U.S. Department of Energy joined the California Energy Commission in funding a project to begin to examine the technical, economic and institutional (policy and regulatory) aspects of energy-efficient community development. That research project was known as the Chula Vista Research Project for the host California community that co-sponsored the initiative. The researches proved that the strategic integration of the selected and economically viable buildings energy efficiency (EE) measures, photovoltaics (PV), distributed generation (DG), and district cooling can produce significant reductions in aggregate energy consumption, peak demand and emissions, compared to the developer/builder's proposed baseline approach. However, the central power plant emission reductions achieved through use of the EE-DG option would increase local air emissions. The electric and natural gas utility infrastructure impacts associated with the use of the EE and EE-PV options were deemed relatively insignificant while use of the EE-DG option would result in a significant reduction of necessary electric distribution facilities to serve a large-scale development project. The results of the Chula Vista project are detailed in three separate documents: (1) Energy-Efficient Community Development in California; Chula Vista Research Project report contains a detailed description of the research effort and findings. This includes the methodologies, and tools used and the analysis of the efficiency, economic and emissions impacts of alternative energy technology and community design options for two development sites. Research topics covered included: (a) Energy supply, demand, and control technologies and related strategies for structures; (b) Application of locally available renewable energy resources including solar thermal and PV technology and on-site power generation with heat recovery; (c) Integration of local energy resources into district energy systems and existing energy utility networks; (d) Alternative land-use design and development options and their impact on energy efficiency and urban runoff, emissions and the heat island effect; and (e) Alternative transportation and mobility options and their impact on local emissions. (2) Creating Energy-Efficient Communities in California: A Reference Guide to Barriers, Solutions and Resources report provides the results of an effort to identify the most innovative existing and emerging public policy, incentive and market mechanisms that encourage investment in advanced energy technologies and enabling community design options in the State of California and the nation. The report evaluates each of these mechanisms in light of the preceding research and concludes with a set of recommended mechanisms designed for consideration by relevant California State agencies, development and finance industry associations, and municipal governments. (3) Creating Energy-Efficient Communities in California: A Technical Reference Guide to Building and Site Design report contains a set of selected commercially viable energy technology and community design options for high-efficiency, low-impact community development in California. It includes a summary of the research findings referenced above and recommendations for energy technology applications and energy-efficient development strategies for residential, commercial and institutional structures and supporting municipal infrastructure for planned communities. The document also identifies design options, technology applications and development strategies that are applicable to urban infill projects.
Gas Technology Institute
Orange and Rockland Utilities (Electric)- Residential Appliance Recycling Program
Energy.gov (U.S. Department of Energy (DOE))
Orange and Rockland Utilities provides rebates for residential customers for recycling older, inefficient refrigerators and freezers. All appliances must meet the program requirements listed on the...
Orange and Rockland Utilities (Electric)- Residential Efficiency Program (New York)
1958. �Legal Battle Over Rio Gas Rights Opens: 20 AttorneysRio Vista discovers gas���������������..40 Part 1: Creationfor new economic avenues: The gas discovery�����..58 1. The
Moving Towards Zero Energy Homes: Vista Montana, Watsonville, California (Fact Sheet)
Fact sheet describes the energy efficient and solar energy features of the Vista Montana Zero Energy Home, participant in the Zero Energy Homes initiative.
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Monte Carlo fundamentals
This report is composed of the lecture notes from the first half of a 32-hour graduate-level course on Monte Carlo methods offered at KAPL. These notes, prepared by two of the principle developers of KAPL`s RACER Monte Carlo code, cover the fundamental theory, concepts, and practices for Monte Carlo analysis. In particular, a thorough grounding in the basic fundamentals of Monte Carlo methods is presented, including random number generation, random sampling, the Monte Carlo approach to solving transport problems, computational geometry, collision physics, tallies, and eigenvalue calculations. Furthermore, modern computational algorithms for vector and parallel approaches to Monte Carlo calculations are covered in detail, including fundamental parallel and vector concepts, the event-based algorithm, master/slave schemes, parallel scaling laws, and portability issues.
Brown, F.B.; Sutton, T.M.
Blue, green, orange, and red upconversion laser
DOE Patents (OSTI)
A laser for outputting visible light at the wavelengths of blue, green, orange and red light. This is accomplished through the doping of a substrate, such as an optical fiber or waveguide, with Pr.sup.3+ ions and Yb.sup.3+ ions. A light pump such as a diode laser is used to excite these ions into energy states which will produce lasing at the desired wavelengths. Tuning elements such as prisms and gratings can be employed to select desired wavelengths for output.
Xie, Ping (San Jose, CA); Gosnell, Timothy R. (Sante Fe, NM)
A laser is disclosed for outputting visible light at the wavelengths of blue, green, orange and red light. This is accomplished through the doping of a substrate, such as an optical fiber or waveguide, with Pr{sup 3+} ions and Yb{sup 3+} ions. A light pump such as a diode laser is used to excite these ions into energy states which will produce lasing at the desired wavelengths. Tuning elements such as prisms and gratings can be employed to select desired wavelengths for output. 11 figs.
Xie, P.; Gosnell, T.R.
Quantum Monte Carlo for
Quantum Monte Carlo for the Electronic Structure of Atoms and Molecules Brian Austin Lester Group, U.C. Berkeley BES Requirements Workshop Rockville, MD February 9, 2010 Outline...
New Mexico State University Dial-up Configurations for Windows Vista
New Mexico State University Dial-up Configurations for Windows Vista To use NMSU campus dial-up on your Windows Vista computer, you will need a modem and these instructions to connect. You will also. From the Connect to a network window, click on Set up a connection or network from the bottom set
Castillo, Steven P.
Biomasse mit Satellit und PROMET Vista 2011 Tagung Energiemeteorologie, Bremerhaven, 6.4.2011
Biomasse mit Satellit und PROMET © Vista 2011 Tagung Energiemeteorologie, Bremerhaven, 6.4.2011 Dr PROMET #12;Biomasse mit Satellit und PROMET © Vista 2011 Motivation · Für die Biogasproduktion ist eine Vorhersagen zu erhalten. · Die Fernerkundung mit Satelliten kann die oberirdische, grüne Biomasse räumlich
Heinemann, Detlev
Orange County REMC - Energy Efficient Equipment Rebate Program | Department
Orange County REMC - Energy Efficient Equipment Rebate Program Orange County REMC - Energy Efficient Equipment Rebate Program Orange County REMC - Energy Efficient Equipment Rebate Program < Back Eligibility Commercial Industrial Low-Income Residential Multi-Family Residential Residential Savings Category Heating & Cooling Commercial Heating & Cooling Cooling Heat Pumps Appliances & Electronics Commercial Lighting Lighting Water Heating Program Info State Indiana Program Type Utility Rebate Program Rebate Amount Electric Water Heaters: $25 - $150 Hybrid Heat Pump Water Heater: $300 - $400 Central Air Conditioning: $100 - $200 Air-Source Heat Pumps: $200 - $800 Geothermal Heat Pumps: $1,000 ETS Systems: varies CFL bulbs: see program web site Provider Orange County REMC Orange County REMC offers incentives for members to improve the energy
Papillion-LaVista South High School Wind Project | Open Energy Information
Papillion-LaVista South High School Wind Project Papillion-LaVista South High School Wind Project Jump to: navigation, search Name Papillion-LaVista South High School Wind Project Facility Papillion-LaVista South High School Sector Wind energy Facility Type Community Wind Location NE Coordinates 41.146679°, -96.079178° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":41.146679,"lon":-96.079178,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Orange & Rockland Utils Inc | Open Energy Information
Orange & Rockland Utils Inc Orange & Rockland Utils Inc (Redirected from Orange & Rockland) Jump to: navigation, search Name Orange & Rockland Utils Inc Place New York Utility Id 14154 Utility Location Yes Ownership I NERC Location NPCC NERC NPCC Yes Activity Transmission Yes Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png SC1 Residential (Multiple Bills, Full Service) Residential SC1 Residential (Multiple Bills, Retail Service) SC1 Residential (Single Bill, Retail Service) SC1 Residential - Residential SC15 Buyback Service SC15 Buyback Service SC16 Flood Lighting Sodium Vapor Overhead and Underground 250w (Customer
Orange County - Wind Permitting Standards | Department of Energy
Orange County - Wind Permitting Standards Orange County - Wind Permitting Standards Orange County - Wind Permitting Standards < Back Eligibility Agricultural Commercial Residential Savings Category Wind Buying & Making Electricity Program Info State California Program Type Solar/Wind Permitting Standards Provider OC Planning In December 2010, the County of Orange Board of Supervisors adopted small wind performance and development standards (Ord. No. 10-020) in order to promote distributed generation systems in non-urbanized areas (as defined in Government Code Section 65944(d)(2)) within the unincorporated territory. Permitting standards are for systems of 50 kW or less per customer site, for which the energy is primarily for on-site consumption. Height: For systems 45 feet tall or less, a use permit must be approved by
Monte Carlo Neutrino Oscillations
We demonstrate that the effects of matter upon neutrino propagation may be recast as the scattering of the initial neutrino wavefunction. Exchanging the differential, Schrodinger equation for an integral equation for the scattering matrix S permits a Monte Carlo method for the computation of S that removes many of the numerical difficulties associated with direct integration techniques.
James P. Kneller; Gail C. McLaughlin
The VISTA spacecraft: Advantages of ICF (Inertial Confinement Fusion) for interplanetary fusion propulsion applications
Inertial Confinement Fusion (ICF) is an attractive engine power source for interplanetary manned spacecraft, especially for near-term missions requiring minimum flight duration, because ICF has inherent high power-to-mass ratios and high specific impulses. We have developed a new vehicle concept called VISTA that uses ICF and is capable of round-trip manned missions to Mars in 100 days using A.D. 2020 technology. We describe VISTA's engine operation, discuss associated plasma issues, and describe the advantages of DT fuel for near-term applications. Although ICF is potentially superior to non-fusion technologies for near-term interplanetary transport, the performance capabilities of VISTA cannot be meaningfully compared with those of magnetic-fusion systems because of the lack of a comparable study of the magnetic-fusion systems. We urge that such a study be conducted.
Orth, C.D.; Klein, G.; Sercel, J.; Hoffman, N.; Murray, K.; Chang-Diaz, F.
Orange and Rockland Utilities (Electric) - Commercial Efficiency Programs |
Orange and Rockland Utilities (Electric) - Commercial Efficiency Orange and Rockland Utilities (Electric) - Commercial Efficiency Programs Orange and Rockland Utilities (Electric) - Commercial Efficiency Programs < Back Eligibility Commercial Fed. Government Industrial Institutional Local Government Multi-Family Residential Nonprofit Schools State Government Savings Category Heating & Cooling Commercial Heating & Cooling Cooling Other Heat Pumps Appliances & Electronics Commercial Lighting Lighting Maximum Rebate Prescriptive Rebates: 50% of cost Program Info Funding Source System Benefits Charge Start Date 4/1/2010 State New York Program Type Utility Rebate Program Rebate Amount Small Business Lighten Up Energy Savings Evaluation and CFLs: Free A/C A/C > 65 kBTU/h: $35/ton (11.5 EER); $55 (12 EER) Heat Pumps 14 SEER or 11.5 EER: $50-$65/ton
TreeQ-VISTA: An Interactive Tree Visualization Tool withFunctional Annotation Query Capabilities
Summary: We describe a general multiplatform exploratorytool called TreeQ-Vista, designed for presenting functional annotationsin a phylogenetic context. Traits, such as phenotypic and genomicproperties, are interactively queried from a relational database with auser-friendly interface which provides a set of tools for users with orwithout SQL knowledge. The query results are projected onto aphylogenetic tree and can be displayed in multiple color groups. A richset of browsing, grouping and query tools are provided to facilitatetrait exploration, comparison and analysis.Availability: The program,detailed tutorial and examples are available online athttp://genome-test.lbl.gov/vista/TreeQVista.
Gu, Shengyin; Anderson, Iain; Kunin, Victor; Cipriano, Michael; Minovitsky, Simon; Weber, Gunther; Amenta, Nina; Hamann, Bernd; Dubchak,Inna
City of Chula Vista This page outlines solar PV incentives, financing mechanisms, permitting process, and
- Thursday 8:00AM - 5:00PM · Federal Solar Incentives o Residential Renewable Energy Tax Credit · A taxpayer_Code=U S02F&re=1&ee=1 · Property Assessed Clean Energy (PACE) Programs o CaliforniaFIRST - The CityCity of Chula Vista This page outlines solar PV incentives, financing mechanisms, permitting
Overview of the VISTA Spacecraft Concept Powered by Inertial Confinement Fusion
VISTA was conceived through a detailed systems analysis as a viable, realistic, and defensible spacecraft concept based on advanced ICF technology but existing or near-term technology for other systems. It is a conical self-contained single-stage piloted spacecraft in which a magnetic thrust chamber directs the plasma emissions from inertial confinement fusion (ICF) targets into a rearward exhaust. VISTA's propulsion system is therefore unique because it is based on (1) a rather mature technology (ICF), which is known to work with sufficient driver input; (2) direct heating of all expellant by the fusion process, thus providing high mass flow rates without significant degradation of jet efficiency; and (3) a magnetic thrust chamber, which avoids the plasma thermalization and resultant degradation of specific impulse that are unavoidable with the use of mechanical thrust chambers. VISTA therefore has inherently high power/mass ratios and high specific impulses. With advanced ICF technology, ultra-fast roundtrips (RTs) to objects within the solar system are possible (e.g., {ge}145 days RT to Mars, {ge}7 years RT to Pluto). Such short-duration missions are imperative to minimize the human physiological deteriorations arising from zero gravity and the cosmic-radiation. In addition, VISTA offers on-board artificial gravity and propellant-based shielding from cosmic rays, thus reducing the physiological deteriorations to insignificant levels. In this paper, we give an overview of the various vehicle systems for this concept, estimate the general missions performance capabilities for interplanetary missions, and describe in detail the performance for the baseline mission of a piloted roundtrip to Mars with a 100-ton payload. Items requiring further research include a reduction of the wet mass from its baseline value of 6,000 metric tons, and the development of fast ignition or its equivalent to provide target gains in excess of several hundred. With target gains well above several hundred, there is no other known technology that can compete with VISTA's performance.
trains allow observation of "movies" of dynamic events on the microsecond timescale. The Isotope Production Facility * uses 100-MeV protons impinging on specialized targets to...
Vista at CDF: Results of a model-independent search for new physics in 927 pb**-1 at CDF
A global, model-independent search for high-pT exotic phenomena is presented using 927 pb{sup -1} of CDF II data. The search algorithms employed in this analysis are Vista and Sleuth. These proceedings focus on Vista, including a description of the method and a summary of results.
Choudalakis, Georgios; /MIT, LNS
City of Orange City, Iowa (Utility Company) | Open Energy Information
Orange City Orange City Place Iowa Utility Id 14159 Utility Location Yes Ownership M NERC Location MRO NERC MRO Yes Activity Distribution Yes Alt Fuel Vehicle Yes Alt Fuel Vehicle2 Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png Commercial Rate Commercial Industrial Rate Industrial Residential Rate Residential Security Lighting 150 W Lighting Security Lighting 175W Lighting Security Lighting 400 W Lighting Average Rates Residential: $0.0858/kWh Commercial: $0.0863/kWh Industrial: $0.0735/kWh References ↑ "EIA Form EIA-861 Final Data File for 2010 - File1_a" Retrieved from
South Orange, New Jersey: Energy Resources | Open Energy Information
Orange, New Jersey: Energy Resources Orange, New Jersey: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 40.7489897°, -74.2612583° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":40.7489897,"lon":-74.2612583,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
70-622: Supporting and Troubleshooting Application on a Microsoft Windows Vista Client for Enterprise Support Technicians Package
The latest publication in the Microsoft Official Academic Course series for IT Professionals, this coursecovers the Windows Vista client mapping to the new Microsoft Certified IT Professional examination 70-622 for Enterprise Support Technicians. A comprehensive ...
Microsoft Official Academic Course
Orange County Great Park Welcomes U.S. Department of Energy...
CONTACT: MARCUS GINNATY 949-724-6574 Orange County Great Park Welcomes U.S. Department of Energy Solar Decathlon 2013 Collegiate Teams * Representatives from 20 collegiate teams...
Monte Carlo Methods and Partial Differential Equations ...
... Up, Monte Carlo Methods and Partial Differential Equations: Algorithms and Implications for High-Performance Computing. ...
Orang-utan feeding behaviour in Sabangau, Central Kalimantan
, Andrea H�ing, Alexandra Gray, Okto, Ella, Marie Hammard and many OuTrop volunteers. I would also like to thank Laura D�Arcy, Laura Graham, Angela viii Benton-Browne, Ben Buckley, Marc Dragiewicz, Carly Waterman and Rosalie Dench. The amazing Ibu... also Muir et al., 1998, 2000; Warren et al., 2001; Brandon-Jones et al., 2004). The different (sub-) species will hybridise in captivity, but survival rates among Sumatra- Borneo hybrids are much lower, and captive Bornean orang-utans, many...
Harrison, Mark Edward
Reflectance Vis/NIR spectroscopy for nondestructive taste characterization of Valencia oranges
The feasibility of reflectance Vis/NIR spectroscopy was investigated for taste characterization of Valencia oranges based on taste attributes including soluble solids content (SSC) and titratable acidity (TA), as well as taste indices including SSC to ... Keywords: BrimA, Nondestructive, Taste, Valencia orange, Vis/NIR spectroscopy
Bahareh Jamshidi; Saeid Minaei; Ezzedin Mohajerani; Hassan Ghassemian
California Society of Professional Engineers and UCI Host Orange County MATHCOUNTS
California Society of Professional Engineers and UCI Host Orange County MATHCOUNTS Competition Juan Capistrano converged at the Student Union of the University of California at Irvine on Saturday was conducted by the Orange County Chapter of the California Society of Professional Engineers (CSPE
Russo, Bernard
Microsoft Word - CX_FINAL_FOG_VISTA_VIEW_FIELDS_06-21-13
June 19, 2013 June 19, 2013 REPLY TO ATTN OF: KEC-4 SUBJECT: Environmental Clearance Memorandum Emanuel Jaramillo Project Manager - TEP-TPP-1 Proposed Action: Vista View Fields Land Acquisition Project Work Order No.: Work Order #327332 Categorical Exclusion Applied (from Subpart D, 10 C.F.R. Part 1021): B1.25 Real property transfers for cultural resources protection, habitat preservation, and wildlife management Location: Township 1 North, Range 5 East, Section 19; Tax Lot 600, Skamania County, Washington Proposed by: Bonneville Power Administration (BPA) Description of the Proposed Action: BPA proposes to fund the acquisition of a 15.72-acre parcel in Skamania County, Washington. The funding would be provided to the Friends of the
Jump to: navigation, search Jump to: navigation, search Name Orange & Rockland Utils Inc Place New York Utility Id 14154 Utility Location Yes Ownership I NERC Location NPCC NERC NPCC Yes Activity Transmission Yes Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png SC1 Residential (Multiple Bills, Full Service) Residential SC1 Residential (Multiple Bills, Retail Service) SC1 Residential (Single Bill, Retail Service) SC1 Residential - Residential SC15 Buyback Service SC15 Buyback Service SC16 Flood Lighting Sodium Vapor Overhead and Underground 250w (Customer owned, retail service, single bill)
Orange County Rural E M C | Open Energy Information
County Rural E M C County Rural E M C Jump to: navigation, search Name Orange County Rural E M C Place Indiana Utility Id 14160 Utility Location Yes Ownership C NERC Location RFC NERC RFC Yes Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png Rate 101- 2012 Rate Schedule for Standard Service Residential Rate 104 and 106- 2012 Rate Schedule for Electric Thermal Storage (ETS) Residential Rate 105- 2012 Rate Schedule for Dual Fuel Service Commercial Rate 177- 2012 Rate Schedule for Security Lighting, Security Lighting- 100 W HPS (45 kwh) Lighting Rate 177- 2012 Rate Schedule for Security Lighting, Security Lighting- 175W
Monte Carlo Methods in Chemistry
Monte Carlo methods fulfil an important dual role. At a specific level, they provide a general-purpose numerical approach to problems in a wide range of topics. Using such methods, we can explore the characteristics of specific systems without introducing ...
Jim Doll; David L. Freeman
VISTA -- A Vehicle for Interplanetary Space Transport Application Powered by Inertial Confinement Fusion
Inertial Confinement Fusion (ICF) is an ideal technology to power self-contained single-stage piloted (manned) spacecraft within the solar system because of its inherently high power/mass ratios and high specific impulses (i.e., high exhaust velocities). These technological advantages are retained when ICF is utilized with a magnetic thrust chamber, which avoids the plasma thermalization and resultant degradation of specific impulse that are unavoidable with the use of mechanical thrust chambers. We started with Rod Hyde's 1983 description of an ICF-powered engine concept using a magnetic thrust chamber, and conducted a more detailed systems study to develop a viable, realistic, and defensible spacecraft concept based on ICF technology projected to be available in the first half of the 21st century. The results include an entirely new conical spacecraft conceptual design utilizing near-existing radiator technology. We describe the various vehicle systems for this new concept, estimate the missions performance capabilities for general missions to the planets within the solar system, and describe in detail the performance for the baseline mission of a piloted roundtrip to Mars with a 100-ton payload. For this mission, we show that roundtrips totaling {ge}145 days are possible with advanced DT fusion technology and a total (wet) spacecraft mass of about 6000 metric tons. Such short-duration missions are advantageous to minimize the known cosmic-radiation hazards to astronauts, and are even more important to minimize the physiological deteriorations arising from zero gravity. These ICF-powered missions are considerably faster than those available using chemical or nuclear-electric-propulsion technologies with minimum-mass vehicle configurations. VISTA also offers onboard artificial gravity and propellant-based shielding from cosmic rays, thus reducing the known hazards and physiological deteriorations to insignificant levels. We emphasize, however, that the degree to which an ICF-powered vehicle can outperform a vehicle using any other realistic technology depends on the degree to which terrestrial-based ICF research can develop the necessary energy gain from ICF targets. With aggressive progress in such terrestrial research, VISTA will be able to make roundtrip missions to Pluto in {approx}7 years, and missions to points just beyond the solar system within a human lifetime.
Office of Information Technology University of Minnesota 1 Note: WebVista to Moodle Transition by August 2012
and, instead, focus on Moodle as the sole centrally-supported Course Management System (CMS, visit the Change Management website. Scheduled Maintenance WebVista has time reserved for scheduled maintenance windows is published on the System Status page. On the Friday preceding the scheduled maintenance
Amin, S. Massoud
Downloading Windows in Mori Operating systems (e.g. Windows 7, Vista and XP) can be displayed in te reo Mori
1 Downloading Windows in Mori Operating systems (e.g. Windows 7, Vista and XP) can be displayed are freely available from the Microsoft website. The interface packs are available for Windows 7, Vista and XP. Follow the link and click Download under the appropriate version for your computer. http://windows.microsoft.com/en-US/windows
Keegan, Te Taka
The path forward: Monte Carlo Convergence discussion
This is a summary of 'the path forward' discussion session of the NuInt09 workshop which focused on Monte Carlo event generators. The main questions raised as part of this discussion are: how to make Monte Carlo generators more reliable and how important it is to work on a universal Monte Carlo generator of events? In this contribution, several experts in the field summarize their views, as presented at the workshop.
Andreopoulos, Costas [Rutherford Appleton Laboratory, STFC Oxfordshire OX11 0QX (United Kingdom); Gallagher, Hugh [Tufts University, Medford, Massachusetts (United States); Hayato, Yoshinari [Kamioka Observatory, ICRR, University of Tokyo Higashi-Mozumi 456, Kamioka-cho, Hida-city Gifu 506-1205 (Japan); Sobczyk, Jan T. [Institute of Theoretical Physics, Wroclaw, University Poland (Poland); Walter, Chris [Department of Physics, Duke University, Durham, NC 27708 (United States); Zeller, Sam [Los Alamos National Laboratory, Los Alamos, NM (United States)
Optimal generalized truncated sequential Monte Carlo test
When it is not possible to obtain the analytical null distribution of a test statistic U, Monte Carlo hypothesis tests can be used to perform the test. Monte Carlo tests are commonly used in a wide variety of applications, including spatial statistics, ... Keywords: 62L05, 62L15, 65C05, Execution time, Power loss, Resampling risk, p-value density
Ivair R. Silva, Renato M. Assun��o
The MC21 Monte Carlo Transport Code
MC21 is a new Monte Carlo neutron and photon transport code currently under joint development at the Knolls Atomic Power Laboratory and the Bettis Atomic Power Laboratory. MC21 is the Monte Carlo transport kernel of the broader Common Monte Carlo Design Tool (CMCDT), which is also currently under development. The vision for CMCDT is to provide an automated, computer-aided modeling and post-processing environment integrated with a Monte Carlo solver that is optimized for reactor analysis. CMCDT represents a strategy to push the Monte Carlo method beyond its traditional role as a benchmarking tool or ''tool of last resort'' and into a dominant design role. This paper describes various aspects of the code, including the neutron physics and nuclear data treatments, the geometry representation, and the tally and depletion capabilities.
Sutton TM, Donovan TJ, Trumbull TH, Dobreff PS, Caro E, Griesheimer DP, Tyburski LJ, Carpenter DC, Joo H
Data Decomposition of Monte Carlo Particle Transport Simulations...
Data Decomposition of Monte Carlo Particle Transport Simulations via Tally Servers Title Data Decomposition of Monte Carlo Particle Transport Simulations via Tally Servers...
Detection, size, measurement and structural analysis limits for the 2MASS, UKIDSS-LAS & VISTA VIKING surveys
The 2MASS, UKIDSS-LAS and VISTA VIKING surveys have all now observed the GAMA 9hr region in the $K_s$ band. Here we compare the detection rates, photometry, basic size measurements, and single-component GALFIT structural measurements for a sample of 37,591 galaxies. We explore the sensitivity limits where the data agree for a variety of issues including: detection, star-galaxy separation, photometric measurements, size and ellipticity measurements, and S\\'{e}rsic measurements. We find that 2MASS fails to detect at least 20% of the galaxy population within all magnitude bins, however for those that are detected we find photometry is robust ($\\pm$ 0.2 mag) to 14.7 AB mag and star-galaxy separation to 14.8 AB mag. For UKIDSS-LAS we find incompleteness starts to enter at a flux limit of 18.9 AB mag, star-galaxy separation is robust to 16.3 AB mag and structural measurements are robust to 17.7 AB mag. VISTA VIKING data is complete to approximately 20.0 AB mag and structural measurements appear robust to 18.8 AB ma...
Andrews, Stephen K; Driver, Simon P; Robotham, Aaron S G
Monte Carlo simulation in financial engineering
This paper reviews the use of Monte Carlo simulation in the field of financial engineering. It focuses on several interesting topics and introduces their recent development, including path generation, pricing American-style derivatives, evaluating Greeks ...
Nan Chen; L. Jeff Hong
Exponential convergence with adaptive Monte Carlo
For over a decade, it has been known that exponential convergence on discrete transport problems was possible using adaptive Monte Carlo techniques. Now, exponential convergence has been empirically demonstrated on a spatially continuous problem.
Booth, T.E.
Canudos/Belo Monte: imagens contando hist�ria.
??O presente exerc�cio objetiva construir uma leitura da Guerra de Canudos/Belo Monte tendo como documentos centrais as fotos de Fl�vio de Barros. Justifica-se tal trabalho� (more)
S�rgio Armando Diniz Guerra
Monte Carlo simulation in systems biology
2 The history of Monte Carlo Sampling in Systems Biology 1.1simulation tools: the systems biology workbench and biospiceCellular and Molecular Biology. ASM Press, Washington
Schellenberger, Jan
EPRI Transmission Line Reference Book: Wind-Induced Conductor Motion (Orange Book) Revision
This report is an updated edition of the longtime industry standard on vibration, EPRI Transmission Line Reference Book: Wind-Induced Conductor Motion, the "Orange Book," which was last issued in 1979. Publication of this new edition is the culmination of three years of research by an international team of experts in the field. The report includes the latest information on research, technology, and materials and represents a significant contribution to the global industry of electric power transmission.
The Rational Hybrid Monte Carlo Algorithm
The past few years have seen considerable progress in algorithmic development for the generation of gauge fields including the effects of dynamical fermions. The Rational Hybrid Monte Carlo (RHMC) algorithm, where Hybrid Monte Carlo is performed using a rational approximation in place the usual inverse quark matrix kernel is one of these developments. This algorithm has been found to be extremely beneficial in many areas of lattice QCD (chiral fermions, finite temperature, Wilson fermions etc.). We review the algorithm and some of these benefits, and we compare against other recent algorithm developements. We conclude with an update of the Berlin wall plot comparing costs of all popular fermion formulations.
M. A. Clark
Monte Carlo Renormalization Group: a review
The logic and the methods of Monte Carlo Renormalization Group (MCRG) are reviewed. A status report of results for 4-dimensional lattice gauge theories derived using MCRG is presented. Existing methods for calculating the improved action are reviewed and evaluated. The Gupta-Cordery improved MCRG method is described and compared with the standard one. 71 refs., 8 figs.
Gupta, R.
Wireless connection instructions -Windows This document outlines the procedure for setting up Windows7, Vista or XP to use the College wireless network. It assumes
Wireless connection instructions - Windows This document outlines the procedure for setting up Windows7, Vista or XP to use the College wireless network. It assumes that you have already connected your Wireless Networks window Registering your computer Start your web browser, ie. Internet Explorer Your
Goldschmidt, Christina
Relevance of accurate Monte Carlo modeling in nuclear medical imaging
Monte Carlo techniques have become popular in different areas of medical physics with advantage of powerful computing systems. In particular
Habib Zaidi
Condensed history Monte Carlo methods for photon transport problems
We study methods for accelerating Monte Carlo simulations that retain most of the accuracy of conventional Monte Carlo algorithms. These methods - called Condensed History (CH) methods - have been very successfully used to model the transport of ionizing ... Keywords: Condensed history models, Monte Carlo methods, Radiative transport equation
Katherine Bhan; Jerome Spanier
Solving Systems of Linear Equations with Relaxed Monte Carlo Method
The problem of solving systems of linear algebraic equations by parallel Monte Carlo numerical methods is considered. A parallel Monte Carlo method with relaxation is presented. This is a report of a research in progress, showing the effectiveness of ... Keywords: Monte Carlo method, linear solver, parallel algorithms, systems of linear algebraic equations
Chih Jeng Kenneth Tan
QWalk: A quantum Monte Carlo program for electronic structure
We describe QWalk, a new computational package capable of performing quantum Monte Carlo electronic structure calculations for molecules and solids with many electrons. We describe the structure of the program and its implementation of quantum Monte ... Keywords: Monte Carlo, Quantum mechanics, Stochastic methods
Lucas K. Wagner; Michal Bajdich; Lubos Mitas
Mont Alto Borough | Open Energy Information
Alto Borough Alto Borough Jump to: navigation, search Name Mont Alto Borough Place Pennsylvania Utility Id 12817 Utility Location Yes Ownership M NERC Location RFC NERC RFC Yes Activity Buying Transmission Yes Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png Commercial Commercial Residential Residential Average Rates Residential: $0.1460/kWh Commercial: $0.0899/kWh Industrial: $0.1480/kWh References ↑ "EIA Form EIA-861 Final Data File for 2010 - File1_a" Retrieved from "http://en.openei.org/w/index.php?title=Mont_Alto_Borough&oldid=411118"
Monte Carlo Simulation for Particle Detectors
Monte Carlo simulation is an essential component of experimental particle physics in all the phases of its life-cycle: the investigation of the physics reach of detector concepts, the design of facilities and detectors, the development and optimization of data reconstruction software, the data analysis for the production of physics results. This note briefly outlines some research topics related to Monte Carlo simulation, that are relevant to future experimental perspectives in particle physics. The focus is on physics aspects: conceptual progress beyond current particle transport schemes, the incorporation of materials science knowledge relevant to novel detection technologies, functionality to model radiation damage, the capability for multi-scale simulation, quantitative validation and uncertainty quantification to determine the predictive power of simulation. The R&D on simulation for future detectors would profit from cooperation within various components of the particle physics community, and synerg...
Pia, Maria Grazia
Status of Monte Carlo at Los Alamos
At Los Alamos the early work of Fermi, von Neumann, and Ulam has been developed and supplemented by many followers, notably Cashwell and Everett, and the main product today is the continuous-energy, general-purpose, generalized-geometry, time-dependent, coupled neutron-photon transport code called MCNP. The Los Alamos Monte Carlo research and development effort is concentrated in Group X-6. MCNP treats an arbitrary three-dimensional configuration of arbitrary materials in geometric cells bounded by first- and second-degree surfaces and some fourth-degree surfaces (elliptical tori). Monte Carlo has evolved into perhaps the main method for radiation transport calculations at Los Alamos. MCNP is used in every technical division at the Laboratory by over 130 users about 600 times a month accounting for nearly 200 hours of CDC-7600 time.
Thompson, W.L.; Cashwell, E.D.
Osage Orange
hunt wild game, there have been herdsmen and farmers who have had to build fences. Fence building and fence repairing, whether they be stone walls, living thorn hedges, rail...
Guideline of Monte Carlo calculation. Neutron/gamma ray transport simulation by Monte Carlo method
This report condenses basic theories and advanced applications of neutron/gamma ray transport calculations in many fields of nuclear energy research. Chapters 1 through 5 treat historical progress of Monte Carlo methods, general issues of variance reduction technique, cross section libraries used in continuous energy Monte Carlo codes. In chapter 6, the following issues are discussed: fusion benchmark experiments, design of ITER, experiment analyses of fast critical assembly, core analyses of JMTR, simulation of pulsed neutron experiment, core analyses of HTTR, duct streaming calculations, bulk shielding calculations, neutron/gamma ray transport calculations of the Hiroshima atomic bomb. Chapters 8 and 9 treat function enhancements of MCNP and MVP codes, and a parallel processing of Monte Carlo calculation, respectively. An important references are attached at the end of this report.
Fission Matrix Capability for MCNP Monte Carlo
In a Monte Carlo criticality calculation, before the tallying of quantities can begin, a converged fission source (the fundamental eigenvector of the fission kernel) is required. Tallies of interest may include powers, absorption rates, leakage rates, or the multiplication factor (the fundamental eigenvalue of the fission kernel, k{sub eff}). Just as in the power iteration method of linear algebra, if the dominance ratio (the ratio of the first and zeroth eigenvalues) is high, many iterations of neutron history simulations are required to isolate the fundamental mode of the problem. Optically large systems have large dominance ratios, and systems containing poor neutron communication between regions are also slow to converge. The fission matrix method, implemented into MCNP[1], addresses these problems. When Monte Carlo random walk from a source is executed, the fission kernel is stochastically applied to the source. Random numbers are used for: distances to collision, reaction types, scattering physics, fission reactions, etc. This method is used because the fission kernel is a complex, 7-dimensional operator that is not explicitly known. Deterministic methods use approximations/discretization in energy, space, and direction to the kernel. Consequently, they are faster. Monte Carlo directly simulates the physics, which necessitates the use of random sampling. Because of this statistical noise, common convergence acceleration methods used in deterministic methods do not work. In the fission matrix method, we are using the random walk information not only to build the next-iteration fission source, but also a spatially-averaged fission kernel. Just like in deterministic methods, this involves approximation and discretization. The approximation is the tallying of the spatially-discretized fission kernel with an incorrect fission source. We address this by making the spatial mesh fine enough that this error is negligible. As a consequence of discretization we get a spatially low-order kernel, the fundamental eigenvector of which should converge faster than that of continuous kernel. We can then redistribute the fission bank to match the fundamental fission matrix eigenvector, effectively eliminating all higher modes. For all computations here biasing is not used, with the intention of comparing the unaltered, conventional Monte Carlo process with the fission matrix results. The source convergence of standard Monte Carlo criticality calculations are, to some extent, always subject to the characteristics of the problem. This method seeks to partially eliminate this problem-dependence by directly calculating the spatial coupling. The primary cost of this, which has prevented widespread use since its inception [2,3,4], is the extra storage required. To account for the coupling of all N spatial regions to every other region requires storing N{sup 2} values. For realistic problems, where a fine resolution is required for the suppression of discretization error, the storage becomes inordinate. Two factors lead to a renewed interest here: the larger memory available on modern computers and the development of a better storage scheme based on physical intuition. When the distance between source and fission events is short compared with the size of the entire system, saving memory by accounting for only local coupling introduces little extra error. We can gain other information from directly tallying the fission kernel: higher eigenmodes and eigenvalues. Conventional Monte Carlo cannot calculate this data - here we have a way to get new information for multiplying systems. In Ref. [5], higher mode eigenfunctions are analyzed for a three-region 1-dimensional problem and 2-dimensional homogenous problem. We analyze higher modes for more realistic problems. There is also the question of practical use of this information; here we examine a way of using eigenmode information to address the negative confidence interval bias due to inter-cycle correlation. We apply this method mainly to four problems: 2D pressurized water reactor (PWR) [6],
Carney, Sean E. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory
In a Monte Carlo criticality calculation, before the tallying of quantities can begin, a converged fission source (the fundamental eigenvector of the fission kernel) is required. Tallies of interest may include powers, absorption rates, leakage rates, or the multiplication factor (the fundamental eigenvalue of the fission kernel, k{sub eff}). Just as in the power iteration method of linear algebra, if the dominance ratio (the ratio of the first and zeroth eigenvalues) is high, many iterations of neutron history simulations are required to isolate the fundamental mode of the problem. Optically large systems have large dominance ratios, and systems containing poor neutron communication between regions are also slow to converge. The fission matrix method, implemented into MCNP[1], addresses these problems. When Monte Carlo random walk from a source is executed, the fission kernel is stochastically applied to the source. Random numbers are used for: distances to collision, reaction types, scattering physics, fission reactions, etc. This method is used because the fission kernel is a complex, 7-dimensional operator that is not explicitly known. Deterministic methods use approximations/discretization in energy, space, and direction to the kernel. Consequently, they are faster. Monte Carlo directly simulates the physics, which necessitates the use of random sampling. Because of this statistical noise, common convergence acceleration methods used in deterministic methods do not work. In the fission matrix method, we are using the random walk information not only to build the next-iteration fission source, but also a spatially-averaged fission kernel. Just like in deterministic methods, this involves approximation and discretization. The approximation is the tallying of the spatially-discretized fission kernel with an incorrect fission source. We address this by making the spatial mesh fine enough that this error is negligible. As a consequence of discretization we get a spatially low-order kernel, the fundamental eigenvector of which should converge faster than that of continuous kernel. We can then redistribute the fission bank to match the fundamental fission matrix eigenvector, effectively eliminating all higher modes. For all computations here biasing is not used, with the intention of comparing the unaltered, conventional Monte Carlo process with the fission matrix results. The source convergence of standard Monte Carlo criticality calculations are, to some extent, always subject to the characteristics of the problem. This method seeks to partially eliminate this problem-dependence by directly calculating the spatial coupling. The primary cost of this, which has prevented widespread use since its inception [2,3,4], is the extra storage required. To account for the coupling of all N spatial regions to every other region requires storing N{sup 2} values. For realistic problems, where a fine resolution is required for the suppression of discretization error, the storage becomes inordinate. Two factors lead to a renewed interest here: the larger memory available on modern computers and the development of a better storage scheme based on physical intuition. When the distance between source and fission events is short compared with the size of the entire system, saving memory by accounting for only local coupling introduces little extra error. We can gain other information from directly tallying the fission kernel: higher eigenmodes and eigenvalues. Conventional Monte Carlo cannot calculate this data - here we have a way to get new information for multiplying systems. In Ref. [5], higher mode eigenfunctions are analyzed for a three-region 1-dimensional problem and 2-dimensional homogenous problem. We analyze higher modes for more realistic problems. There is also the question of practical use of this information; here we examine a way of using eigenmode information to address the negative confidence interval bias due to inter-cycle correlation. We apply this method mainly to four problems: 2D pressurized water reactor (PWR) [6],
Monte Carlo Particle Transport: Algorithm and Performance Overview
National Nuclear Security Administration (NNSA)
Monte Carlo Particle Transport: Monte Carlo Particle Transport: Algorithm and Performance Overview N. A. Gentile, R. J. Procassini and H. A. Scott Lawrence Livermore National Laboratory, Livermore, California, 94551 Monte Carlo methods are frequently used for neutron and radiation trans- port. These methods have several advantages, such as relative ease of programming and dealing with complex meshes. Disadvantages include long run times and statistical noise. Monte Carlo photon transport calcu- lations also often suffer from inaccuracies in matter temperature due to the lack of implicitness. In this paper we discuss the Monte Carlo algo- rithm as it is applied to neutron and photon transport, detail the differ- ences between neutron and photon Monte Carlo, and give an overview of the ways the numerical method has been modified to deal with issues that
Quantum Monte Carlo for vibrating molecules
Quantum Monte Carlo (QMC) has successfully computed the total electronic energies of atoms and molecules. The main goal of this work is to use correlation function quantum Monte Carlo (CFQMC) to compute the vibrational state energies of molecules given a potential energy surface (PES). In CFQMC, an ensemble of random walkers simulate the diffusion and branching processes of the imaginary-time time dependent Schroedinger equation in order to evaluate the matrix elements. The program QMCVIB was written to perform multi-state VMC and CFQMC calculations and employed for several calculations of the H{sub 2}O and C{sub 3} vibrational states, using 7 PES`s, 3 trial wavefunction forms, two methods of non-linear basis function parameter optimization, and on both serial and parallel computers. In order to construct accurate trial wavefunctions different wavefunctions forms were required for H{sub 2}O and C{sub 3}. In order to construct accurate trial wavefunctions for C{sub 3}, the non-linear parameters were optimized with respect to the sum of the energies of several low-lying vibrational states. In order to stabilize the statistical error estimates for C{sub 3} the Monte Carlo data was collected into blocks. Accurate vibrational state energies were computed using both serial and parallel QMCVIB programs. Comparison of vibrational state energies computed from the three C{sub 3} PES`s suggested that a non-linear equilibrium geometry PES is the most accurate and that discrete potential representations may be used to conveniently determine vibrational state energies.
Brown, W.R. [Univ. of California, Berkeley, CA (United States). Chemistry Dept.]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.
Exascale Monte Carlo R&D
Overview of this presentation is (1) Exascale computing - different technologies, getting there; (2) high-performance proof-of-concept MCMini - features and results; and (3) OpenCL toolkit - Oatmeal (OpenCL Automatic Memory Allocation Library) - purpose and features. Despite driver issues, OpenCL seems like a good, hardware agnostic tool. MCMini demonstrates the possibility for GPGPU-based Monte Carlo methods - it shows great scaling for HPC application and algorithmic equivalence. Oatmeal provides a flexible framework to aid in the development of scientific OpenCL codes.
Marcus, Ryan C. [Los Alamos National Laboratory
Monte Carlo simulations on Graphics Processing Units
Implementation of basic local Monte-Carlo algorithms on ATI Graphics Processing Units (GPU) is investigated. The Ising model and pure SU(2) gluodynamics simulations are realized with the Compute Abstraction Layer (CAL) of ATI Stream environment using the Metropolis and the heat-bath algorithms, respectively. We present an analysis of both CAL programming model and the efficiency of the corresponding simulation algorithms on GPU. In particular, the significant performance speed-up of these algorithms in comparison with serial execution is observed.
Vadim Demchik; Alexei Strelchenko
Discrete diffusion Monte Carlo for frequency-dependent radiative transfer
Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations. In this paper, we develop an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold. Above this threshold we employ standard Monte Carlo. With a frequency-dependent test problem, we confirm the increased efficiency of our new DDMC technique.
Densmore, Jeffrey D [Los Alamos National Laboratory; Kelly, Thompson G [Los Alamos National Laboratory; Urbatish, Todd J [Los Alamos National Laboratory
Numerical study of error propagation in Monte Carlo depletion simulations.
??Improving computer technology and the desire to more accurately model the heterogeneity of the nuclear reactor environment have made the use of Monte Carlo depletion� (more)
Wyant, Timothy Joseph
A Kinetic Monte Carlo Model for Material Aging: Simulations of ...
In this paper, we develop a kinetic Monte Carlo framework aiming at ... A Controlled Stress Energy Minimization Method for Coarse-grained Atomistic Simulation.
Visualizing Quantum Monte Carlo Study of Photoprotection via...
Photoprotection via Carotenoids in Photosynthetic Centers Quantum Monte Carlo Study of Photoprotection via Carotenoids in Photosynthetic Centers photosynthesisimage30y2004.jpg The...
HILO: Quasi Diffusion Accelerated Monte Carlo on Hybrid Architectures
HILO: Quasi Diffusion Accelerated Monte Carlo on Hybrid Architectures The Boltzmann transport equation provides high fidelity simulation of a diverse range of kinetic systems....
Energy Monte Carlo (EMCEE) | Open Energy Information
Energy Monte Carlo (EMCEE) Energy Monte Carlo (EMCEE) Jump to: navigation, search Tool Summary LAUNCH TOOL Name: EMCEE and Emc2 Agency/Company /Organization: United States Geological Survey Sector: Energy Focus Area: Non-renewable Energy Topics: Resource assessment Resource Type: Software/modeling tools User Interface: Spreadsheet Website: pubs.usgs.gov/pp/pp1713/26/ Country: United States Cost: Free Northern America Coordinates: 37.09024°, -95.712891° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.09024,"lon":-95.712891,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Quantum Monte Carlo for atoms and molecules
The diffusion quantum Monte Carlo with fixed nodes (QMC) approach has been employed in studying energy-eigenstates for 1--4 electron systems. Previous work employing the diffusion QMC technique yielded energies of high quality for H{sub 2}, LiH, Li{sub 2}, and H{sub 2}O. Here, the range of calculations with this new approach has been extended to include additional first-row atoms and molecules. In addition, improvements in the previously computed fixed-node energies of LiH, Li{sub 2}, and H{sub 2}O have been obtained using more accurate trial functions. All computations were performed within, but are not limited to, the Born-Oppenheimer approximation. In our computations, the effects of variation of Monte Carlo parameters on the QMC solution of the Schroedinger equation were studied extensively. These parameters include the time step, renormalization time and nodal structure. These studies have been very useful in determining which choices of such parameters will yield accurate QMC energies most efficiently. Generally, very accurate energies (90--100% of the correlation energy is obtained) have been computed with single-determinant trail functions multiplied by simple correlation functions. Improvements in accuracy should be readily obtained using more complex trial functions.
Barnett, R.N.
MCNPX (Monte Carlo N-Particle eXtended) is a general-purpose Monte Carlo radiation transport code with three-dimensional geometry and continuous-energy transport of 34 particles and light ions. It contains flexible source and tally options, interactive graphics, and support for both sequential and multi-processing computer platforms. MCNPX is based on MCNP4B, and has been upgraded to most MCNP5 capabilities. MCNP is a highly stable code tracking neutrons, photons and electrons, and using evaluated nuclear data libraries for low-energy interaction probabilities. MCNPX has extended this base to a comprehensive set of particles and light ions, with heavy ion transport in development. Models have been included to calculate interaction probabilities when libraries are not available. Recent additions focus on the time evolution of residual nuclei decay, allowing calculation of transmutation and delayed particle emission. MCNPX is now a code of great dynamic range, and the excellent neutronics capabilities allow new opportunities to simulate devices of interest to experimental particle physics; particularly calorimetry. This paper describes the capabilities of the current MCNPX version 2.6.C, and also discusses ongoing code development.
WATERS, LAURIE S. [Los Alamos National Laboratory; MCKINNEY, GREGG W. [Los Alamos National Laboratory; DURKEE, JOE W. [Los Alamos National Laboratory; FENSIN, MICHAEL L. [Los Alamos National Laboratory; JAMES, MICHAEL R. [Los Alamos National Laboratory; JOHNS, RUSSELL C. [Los Alamos National Laboratory; PELOWITZ, DENISE B. [Los Alamos National Laboratory
Quantum Monte Carlo Endstation for Petascale Computing
NCSU research group has been focused on accomplising the key goals of this initiative: establishing new generation of quantum Monte Carlo (QMC) computational tools as a part of Endstation petaflop initiative for use at the DOE ORNL computational facilities and for use by computational electronic structure community at large; carrying out high accuracy quantum Monte Carlo demonstration projects in application of these tools to the forefront electronic structure problems in molecular and solid systems; expanding the impact of QMC methods and approaches; explaining and enhancing the impact of these advanced computational approaches. In particular, we have developed quantum Monte Carlo code (QWalk, www.qwalk.org) which was significantly expanded and optimized using funds from this support and at present became an actively used tool in the petascale regime by ORNL researchers and beyond. These developments have been built upon efforts undertaken by the PI's group and collaborators over the period of the last decade. The code was optimized and tested extensively on a number of parallel architectures including petaflop ORNL Jaguar machine. We have developed and redesigned a number of code modules such as evaluation of wave functions and orbitals, calculations of pfaffians and introduction of backflow coordinates together with overall organization of the code and random walker distribution over multicore architectures. We have addressed several bottlenecks such as load balancing and verified efficiency and accuracy of the calculations with the other groups of the Endstation team. The QWalk package contains about 50,000 lines of high quality object-oriented C++ and includes also interfaces to data files from other conventional electronic structure codes such as Gamess, Gaussian, Crystal and others. This grant supported PI for one month during summers, a full-time postdoc and partially three graduate students over the period of the grant duration, it has resulted in 13 published papers, 15 invited talks and lectures nationally and internationally. My former graduate student and postdoc Dr. Michal Bajdich, who was supported byt this grant, is currently a postdoc with ORNL in the group of Dr. F. Reboredo and Dr. P. Kent and is using the developed tools in a number of DOE projects. The QWalk package has become a truly important research tool used by the electronic structure community and has attracted several new developers in other research groups. Our tools use several types of correlated wavefunction approaches, variational, diffusion and reptation methods, large-scale optimization methods for wavefunctions and enables to calculate energy differences such as cohesion, electronic gaps, but also densities and other properties, using multiple runs one can obtain equations of state for given structures and beyond. Our codes use efficient numerical and Monte Carlo strategies (high accuracy numerical orbitals, multi-reference wave functions, highly accurate correlation factors, pairing orbitals, force biased and correlated sampling Monte Carlo), are robustly parallelized and enable to run on tens of thousands cores very efficiently. Our demonstration applications were focused on the challenging research problems in several fields of materials science such as transition metal solids. We note that our study of FeO solid was the first QMC calculation of transition metal oxides at high pressures.
Lubos Mitas
Structural Determinats Underlying Photoprotection in the Photoactive Orange Carotenoid Protein of Cyanobacteria
The photoprotective processes of photosynthetic organisms involve the dissipation of excess absorbed light energy as heat. Photoprotection in cyanobacteria is mechanistically distinct from that in plants; it involves the Orange Carotenoid Protein (OCP), a water-soluble protein containing a single carotenoid. The OCP is a new member of the family of blue light photoactive proteins; blue-green light triggers the OCP-mediated photoprotective response. Here we report structural and functional characterization of the wildtype and two mutant forms of the OCP, from the model organism Synechocystis PCC6803. The structural analysis provides highresolution detail of the carotenoidprotein interactions that underlie the optical properties of the OCP, unique among carotenoid-proteins in binding a single pigment per polypeptide chain. Collectively, these data implicate several key amino acids in the function of the OCP and reveal that the photoconversion and photoprotective responses of the OCP to blue-green light can be decoupled.
Wilson, Adjele; Kinney, James N.; Zwart, Petrus H.; Punginelli, Claire; D'Haene, Sandrine; Perreau, Francois; Klein, Michael G.; Kirilovsky, Diana; Kerfeld, Cheryl
Efficient, automated Monte Carlo methods for radiation transport
Monte Carlo simulations provide an indispensible model for solving radiative transport problems, but their slow convergence inhibits their use as an everyday computational tool. In this paper, we present two new ideas for accelerating the convergence ... Keywords: Computational efficiency, Geometrically convergent Monte Carlo algorithms, Transport equation
Rong Kong; Martin Ambrose; Jerome Spanier
Adjoint electron-photon transport Monte Carlo calculations with ITS
A general adjoint coupled electron-photon Monte Carlo code for solving the Boltzmann-Fokker-Planck equation has recently been created. It is a modified version of ITS 3.0, a coupled electronphoton Monte Carlo code that has world-wide distribution. The applicability of the new code to radiation-interaction problems of the type found in space environments is demonstrated.
Lorence, L.J.; Kensek, R.P.; Halbleib, J.A. [Sandia National Labs., Albuquerque, NM (United States); Morel, J.E. [Los Alamos National Lab., NM (United States)
Bold diagrammatic Monte Carlo for the resonant Fermi gas
We provide a comprehensive description of the Bold Diagrammatic Monte Carlo algorithm for the normal resonant Fermi gas that was briefly reported and used in [Nature Phys. 8, 366 (2012)] and [arXiv:1303.6245]. Details are given on all key aspects of the scheme: diagrammatic framework, Monte Carlo moves, ultraviolet asymptotics, and resummation techniques.
Van Houcke, K; Prokof'ev, N; Svistunov, B
Quantum Monte Carlo simulations of solids W. M. C. Foulkes
Quantum Monte Carlo simulations of solids W. M. C. Foulkes CMTH Group, Department of Physics and fixed-node diffusion quantum Monte Carlo methods and how they may be used to calculate the properties of quantum many-body effects and serve as benchmarks against which other techniques may be compared
Wu, Zhigang
Hybrid algorithms in quantum Monte Carlo
With advances in algorithms and growing computing powers, quantum Monte Carlo (QMC) methods have become a leading contender for high accuracy calculations for the electronic structure of realistic systems. The performance gain on recent HPC systems is largely driven by increasing parallelism: the number of compute cores of a SMP and the number of SMPs have been going up, as the Top500 list attests. However, the available memory as well as the communication and memory bandwidth per element has not kept pace with the increasing parallelism. This severely limits the applicability of QMC and the problem size it can handle. OpenMP/MPI hybrid programming provides applications with simple but effective solutions to overcome efficiency and scalability bottlenecks on large-scale clusters based on multi/many-core SMPs. We discuss the design and implementation of hybrid methods in QMCPACK and analyze its performance on current HPC platforms characterized by various memory and communication hierarchies.
Esler, Kenneth P [ORNL; Mcminis, Jeremy [University of Illinois, Urbana-Champaign; Morales, Miguel A [Lawrence Livermore National Laboratory (LLNL); Clark, Bryan K. [Princeton University; Shulenburger, Luke [Sandia National Laboratory (SNL); Ceperley, David M [ORNL
Quantum Ice : a quantum Monte Carlo study
Ice states, in which frustrated interactions lead to a macroscopic ground-state degeneracy, occur in water ice, in problems of frustrated charge order on the pyrochlore lattice, and in the family of rare-earth magnets collectively known as spin ice. Of particular interest at the moment are "quantum spin ice" materials, where large quantum fluctuations may permit tunnelling between a macroscopic number of different classical ground states. Here we use zero-temperature quantum Monte Carlo simulations to show how such tunnelling can lift the degeneracy of a spin or charge ice, stabilising a unique "quantum ice" ground state --- a quantum liquid with excitations described by the Maxwell action of 3+1-dimensional quantum electrodynamics. We further identify a competing ordered "squiggle" state, and show how both squiggle and quantum ice states might be distinguished in neutron scattering experiments on a spin ice material.
Nic Shannon; Olga Sikora; Frank Pollmann; Karlo Penc; Peter Fulde
Monte Carlo calculations of channeling radiation
Results of classical Monte Carlo calculations are presented for the radiation produced by ultra-relativistic positrons incident in a direction parallel to the (110) plane of Si in the energy range 30 to 100 MeV. The results all show the characteristic CR(channeling radiation) peak in the energy range 20 keV to 100 keV. Plots of the centroid energies, widths, and total yields of the CR peaks as a function of energy show the power law dependences of ..gamma../sup 1/ /sup 5/, ..gamma../sup 1/ /sup 7/, and ..gamma../sup 2/ /sup 5/ respectively. Except for the centroid energies and power-law dependence is only approximate. Agreement with experimental data is good for the centroid energies and only rough for the widths. Adequate experimental data for verifying the yield dependence on ..gamma.. does not yet exist.
Bloom, S.D.; Berman, B.L.; Hamilton, D.C.; Alguard, M.J.; Barrett, J.H.; Datz, S.; Pantell, R.H.; Swent, R.H.
Monte Carlo Simulation of Joint Transport of Neutrons Monte Carlo Simulation of Joint Transport of Neutrons
Monte Carlo Simulation of Joint Transport of Neutrons Monte Carlo Simulation of Joint Transport of Neutrons Monte Carlo Simulation of Joint Transport of Neutrons and Photons and Photons Zhitnik Zhitnik A A . . K K . . , , Artemeva Artemeva E.V., E.V., Bakanov Bakanov V.V., V.V., Donskoy Donskoy E.N., E.N., Zalyalov Zalyalov A.N., A.N., Ivanov Ivanov N.V., N.V., Ognev Ognev S.P., S.P., Ronzhin Ronzhin A.B., A.B., Roslov Roslov V.I., V.I., Semenova Semenova T.V. T.V. RFNC-VNIIEF, 607190, Sarov, RFNC-VNIIEF, 607190, Sarov, Nizhni Nizhni Novgorod region Novgorod region The approaches used at VNIIEF to simulate transport of neutrons and photons in standard (with The approaches used at VNIIEF to simulate transport of neutrons and photons in standard (with surface description of region interfaces) and grid geometries are considered in the paper.
Monte Carlo Algorithm for Least Dependent Non-Negative Mixture Decomposition
....................................................................7 Ivan Bedini, Benjamin Nguyen and Georges Gardarin. Guiding the Ontology Matching Process Construction Tool Ivan Bedini 1 , Benjamin Nguyen 2 , Georges Gardarin 2 1 Orange Labs, 42 Rue des Coutures, 14000 Caen, France email@example.com 2 PRiSM Laboratory, University of Versailles, 45
Astakhov, Sergey
Quantification of stochastic uncertainty propagation for Monte Carlo depletion methods in reactor analysis.
??The Monte Carlo method provides powerful geometric modeling capabilities for large problem domains in 3-D; therefore, the Monte Carlo method is becoming popular for 3-D� (more)
Newell, Quentin Thomas
Iterative acceleration methods for Monte Carlo and deterministic criticality calculations
If you have ever given up on a nuclear criticality calculation and terminated it because it took so long to converge, you might find this thesis of interest. The author develops three methods for improving the fission source convergence in nuclear criticality calculations for physical systems with high dominance ratios for which convergence is slow. The Fission Matrix Acceleration Method and the Fission Diffusion Synthetic Acceleration (FDSA) Method are acceleration methods that speed fission source convergence for both Monte Carlo and deterministic methods. The third method is a hybrid Monte Carlo method that also converges for difficult problems where the unaccelerated Monte Carlo method fails. The author tested the feasibility of all three methods in a test bed consisting of idealized problems. He has successfully accelerated fission source convergence in both deterministic and Monte Carlo criticality calculations. By filtering statistical noise, he has incorporated deterministic attributes into the Monte Carlo calculations in order to speed their source convergence. He has used both the fission matrix and a diffusion approximation to perform unbiased accelerations. The Fission Matrix Acceleration method has been implemented in the production code MCNP and successfully applied to a real problem. When the unaccelerated calculations are unable to converge to the correct solution, they cannot be accelerated in an unbiased fashion. A Hybrid Monte Carlo method weds Monte Carlo and a modified diffusion calculation to overcome these deficiencies. The Hybrid method additionally possesses reduced statistical errors.
Urbatsch, T.J.
Kinetic Monte Carlo simulations of nanocrystalline film deposition
A full diffusion kinetic Monte Carlo algorithm is used to model nanocrystalline film deposition, and study the mechanisms of grain nucleation and microstructure formation in such films. The major finding of this work is ...
Ruan, Shiyun
Independent Pixel and Monte Carlo Estimates of Stratocumulus Albedo
Monte Carlo radiative transfer methods are employed here to estimate the plane-parallel albedo bias for marine stratocumulus clouds. This is the bias in estimates of the mesoscale-average albedo, which arises from the assumption that cloud liquid ...
Robert F. Cahalan; William Ridgway; Warren J. Wiscombe; Steven Gollmer; Harshvardhan
Parallel Fission Bank Algorithms in Monte Carlo Criticality Calculations
In this work we describe a new method for parallelizing the source iterations in a Monte Carlo criticality calculation. Instead of having one global fission bank that needs to be synchronized, as is traditionally done, our ...
Romano, Paul Kollath
Low Dose Radiation Research Program: Monte Carlo Track Structure...
Monte Carlo Track Structure Simulations for Low-LET Selected Cell Radiation Studies Walt Wilson Washington State University Tri-Cities Why This Project There are many types of...
Bayesian inverse problems with Monte Carlo forward models
The full application of Bayesian inference to inverse problems requires exploration of a posterior distribution that typically does not possess a standard form. In this context, Markov chain Monte Carlo (MCMC) methods are ...
Bal, Guillaume
Enhancements in Continuous-Energy Monte Carlo Capabilities in SCALE
Monte Carlo tools in SCALE are commonly used in criticality safety calculations as well as sensitivity and uncertainty analysis, depletion, and criticality alarm system analyses. Recent improvements in the continuous-energy data generated by the AMPX code system and significant advancements in the continuous-energy treatment in the KENO Monte Carlo eigenvalue codes facilitate the use of SCALE Monte Carlo codes to model geometrically complex systems with enhanced solution fidelity. The addition of continuous-energy treatment to the SCALE Monaco code, which can be used with automatic variance reduction in the hybrid MAVRIC sequence, provides significant enhancements, especially for criticality alarm system modeling. This paper describes some of the advancements in continuous-energy Monte Carlo codes within the SCALE code system.
Bekar, Kursat B [ORNL; Celik, Cihangir [ORNL; Wiarda, Dorothea [ORNL; Peplow, Douglas E. [ORNL; Rearden, Bradley T [ORNL; Dunn, Michael E [ORNL
Microsoft PowerPoint - 13-02 Monts.pptx
tankAt-tank Characterization for Closure of Hanford Tanks Ping-Rey Jang, Zhiling Long, O. Perry Norton, Walter P. Okhuysen, and David L. Monts Institute for Clean Energy...
Quiet direct simulation Monte-Carlo with random timesteps
Use of a high-order deterministic sampling technique in direct simulation Monte-Carlo (DSMC) simulations eliminates statistical noise and improves computational performance by orders of magnitude. In this paper it is also shown that if a random timestep ... Keywords: 02.50.Ey, 02.70.Tt, 47.11.+j, 52.65.-y, Direct simulation Monte-Carlo, Particle-in-cell methods, Stochastic processess
William Peter
A hybrid transport-diffusion method for Monte Carlo radiative-transfer simulations
Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Monte Carlo particle-transport simulations in diffusive media. If standard Monte Carlo is used in such media, particle histories will consist of many small steps, resulting ... Keywords: Hybrid transport-diffusion, Monte Carlo, Radiative transfer
Jeffery D. Densmore; Todd J. Urbatsch; Thomas M. Evans; Michael W. Buksas
High-Performance Quasi-Monte Carlo Financial Simulation: FPGA vs. GPP vs. GPU
Quasi-Monte Carlo simulation is a special Monte Carlo simulation method that uses quasi-random or low-discrepancy numbers as random sample sets. In many applications, this method has proved advantageous compared to the traditional Monte Carlo simulation ... Keywords: CPU, FPGA, GPU, Maxwell, Quasi-Monte Carlo simulations, option pricing
Xiang Tian; Khaled Benkrid
The major achievements enabled by QMC Endstation grant include * Performance improvement on clusters of x86 multi-core systems, especially on Cray XT systems * New and improved methods for the wavefunction optimizations * New forms of trial wavefunctions * Implementation of the full application on NVIDIA GPUs using CUDA The scaling studies of QMCPACK on large-scale systems show excellent parallel efficiency up to 216K cores on Jaguarpf (Cray XT5). The GPU implementation shows speedups of 10-15x over the CPU implementation on older generation of x86. We have implemented hybrid OpenMP/MPI scheme in QMC to take advantage of multi-core shared memory processors of petascale systems. Our hybrid scheme has several advantages over the standard MPI-only scheme. * Memory optimized: large read-only data to store one-body orbitals and other shared properties to represent the trial wave function and many-body Hamiltonian can be shared among threads, which reduces the memory footprint of a large-scale problem. * Cache optimized: the data associated with an active Walker are in cache during the compute-intensive drift-diffusion process and the operations on an Walker are optimized for cache reuse. Thread-local objects are used to ensure the data affinity to a thread. * Load balanced: Walkers in an ensemble are evenly distributed among threads and MPI tasks. The two-level parallelism reduces the population imbalance among MPI tasks and reduces the number of point-to-point communications of large messages (serialized objects) for the Walker exchange. * Communication optimized: the communication overhead, especially for the collective operations necessary to determine ET and measure the properties of an ensemble, is significantly lowered by using less MPI tasks. The multiple forms of parallelism afforded by QMC algorithms make them ideal candidates for acceleration in the many-core paradigm. We presented the results of our effort to port the QMCPACK simulation code to the NVIDIA CUDA GPU platform. We restructured the CPU algorithms to express additional parallelism, minimize GPU-CPU communication, and efficiently utilize the GPU memory hierarchy. Using mixed precision on GT200 GPUs and MPI for intercommunication and load balancing, we observe typical full-application speedups of approximately 10x to 15x relative to quad-core Xeon CPUs alone, while reproducing the double-precision CPU results within statistical error. We developed an all-electron quantum Monte Carlo (QMC) method for solids that does not rely on pseudopotentials, and used it to construct a primary ultra-high-pressure calibration based on the equation of state of cubic boron nitride. We computed the static contribution to the free energy with the QMC method and obtained the phonon contribution from density functional theory, yielding a high-accuracy calibration up to 900 GPa usable directly in experiment. We computed the anharmonic Raman frequency shift with QMC simulations as a function of pressure and temperature, allowing optical pressure calibration. In contrast to present experimental approaches, small systematic errors in the theoretical EOS do not increase with pressure, and no extrapolation is needed. This all-electron method is applicable to first-row solids, providing a new reference for ab initio calculations of solids and benchmarks for pseudopotential accuracy. We compared experimental and theoretical results on the momentum distribution and the quasiparticle renormalization factor in sodium. From an x-ray Compton-profile measurement of the valence-electron momentum density, we derived its discontinuity at the Fermi wavevector finding an accurate measure of the renormalization factor that we compared with quantum-Monte-Carlo and G0W0 calculations performed both on crystalline sodium and on the homogeneous electron gas. Our calculated results are in good agreement with the experiment. We have been studying the heat of formation for various Kubas complexes of molecular hydrogen on Ti(1,2)ethylene-nH2 using Diffusion Monte Carlo. This work has been started and is o
David Ceperley
DOE Science Showcase - Monte Carlo Methods | OSTI, US Dept of Energy,
Office of Scientific and Technical Information (OSTI)
Monte Carlo Methods Monte Carlo Methods Monte Carlo calculation methods are algorithms for solving various kinds of computational problems by using (pseudo)random numbers. Developed in the 1940s during the Manhattan Project, the Monte Carlo method signified a radical change in how scientists solved problems. Learn about the ways these methods are used in DOE's research endeavors today in "Monte Carlo Methods" by Dr. William Watson, Physicist, OSTI staff. Effects of static particle dispersions on grain growth are studied using SPPARKS simulations Image credit: Sandia National Laboratory Monte Carlo Results in DOE Databases Lab biophysicist invents improvement to Monte Carlo technique, LLNL News Monte Carlo Benchmark software, ESTSC Improved Monte Carlo Renormalization Group Method, DOE R&D
El Monte, California: Energy Resources | Open Energy Information
Monte, California: Energy Resources Monte, California: Energy Resources (Redirected from El Monte, CA) Jump to: navigation, search Equivalent URI DBpedia Coordinates 34.0686206°, -118.0275667° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":34.0686206,"lon":-118.0275667,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
An Overview of Geometry Representation in Monte Carlo Codes
Geometry Representation Geometry Representation in Monte Carlo Codes R.P. Kensek, * B.C. Franke, * T.W. Laub * , L.J. Lorence, * M. R. Martin, * S. Warren † * Sandia National Laboratories, P.O. Box 5800, MS 1179, Albuquerque, NM 87185 † Kansas State University, Manhattan, KS 66506 Geometry representations in production Monte Carlo radiation transport codes used for linear-transport simulations are traditionally limited to combinatorial geometry (CG) topologies. While CG representations of input geometries are efficient to query, they are difficult to construct. In the Integrated-TIGER-Series (ITS) Monte Carlo code suite, a new approach for radiation transport geometry engines has been implemented that allows for Computer Aided Design (CAD), facetted approximations, and other geometry types to simultaneously define an input geometry.
The Monte Carlo Independent Column Approximation Model Intercomparison
The Monte Carlo Independent Column Approximation Model Intercomparison The Monte Carlo Independent Column Approximation Model Intercomparison Project (McMIP) Barker, Howard Meteorological Service of Canada Cole, Jason Meteorological Service of Canada Raisanen, Petri Finnish Meteorological Institute Pincus, Robert NOAA-CIRES Climate Diagnostics Center Morcrette, Jean-Jacques European Centre for Medium-Range Weather Forecasts Li, Jiangnan Canadian Center for Climate Modelling Stephens, Graeme Colorado State University Vaillancourt, Paul Environment Canada Oreopoulos, Lazaros JCET/UMBC and NASA/GSFC Siebesma, Pier KNMI Los, Alexander KNMI Clothiaux, Eugene The Pennsylvania State University Randall, David Colorado State University Iacono, Michael Atmospheric & Environmental Research, Inc. Category: Radiation The Monte Carlo Independent Column Approximation (McICA) method for
Monte Carlo Simulations for Mine Detection
During January, 1998, collaboration between LLNL, UCI and Exdet, Ltd. arranged for the testing and evaluation of a Russian developed antitank mine detection system at the Buried Objects Detection Facility (BODF) located at the Nevada Test Site. BODF is a secured 30-acre facility with approximately 300 live antitank mines that were buried in 1993 and 1994. The burial depths range from a few cm to 15 cm and the various metal- and plastic-case antitank mines each contain 6-12 kg of high explosive. Contractors who have tested their mine detection equipment at BODF include: SAIC, SRI, ERIM, MIT/Lincoln Laboratory and Loral Defense Systems. In addition LLNL researchers have used BODF to test antitank mine detection systems based on: dual-band infrared imaging, hyper-spectral imaging, synthetic aperture impulse radar and micro-impulse radar. In a blind test the Russian operated system obtained the highest score of any technology tested to date at BODF. The system is based on combining information from two separate sensors; one to detect anomalous concentrations of hydrogen and the other to detect if such anomalies also have the correct nitrogen to carbon ratio for high explosives. The detection sensitivity is set by the geometry and type of neutron moderator and filters surrounding the neutron source and detectors. Detection of hydrogen anomalies is a rapid process based on neutron scattering. The handheld instrument on the end of a wand could scan a large area at a rate of 4-5 square meters per minute. Once the hydrogen anomalies were located a second sensor was used to measure the thermal neutron excited gamma-ray spectrum at each hydrogen anomaly to determine whether that location in addition contained high concentrations of nitrogen. The second process was slower, taking up to 5 minutes for each location. The information from both sensors were then examined by the operator and a declaration was made as to whether or not the anomaly was a buried antitank mine. Although the system worked extremely well on all classes of anti-tank mines, the Russian hardware components were inferior to those that are commercially available in the United States, i.e. the NaI(Tl) crystals had significantly higher background levels and poorer resolution than their U.S. counterparts, the electronics appeared to be decades old and the photomultiplier tubes were noisy and lacked gain stabilization circuitry. During the evaluation of this technology, the question that came to mind was: could state-of-the-art sensors and electronics and improved software algorithms lead to a neutron based system that could reliably detect much smaller buried mines; namely antipersonnel mines containing 30-40 grams of high explosive? Our goal in this study was to conduct Monte Carlo simulations to gain better understanding of both phases of the mine detection system and to develop an understanding for the system's overall capabilities and limitations. In addition, we examined possible extensions of this technology to see whether or not state-of-the-art improvements could lead to a reliable anti-personnel mine detection system.
Toor, A.; Marchetti, A.A.
Evaluation of Orange and Rockland Utilities, Inc.`s competitive bidding program for demand-side resources. Final report
The process evaluation reports on the implementation of Orange and Rockland Utilities demand-side bidding program in New York State during 1991 and 1992. The program is implemented by two energy service companies in Orange and rockland`s New York State service territory. The process evaluation methodology included interviews with utility staff (3), energy service company staff (2), and participating (6) and nonparticipating (7) utility customers. The two energy service companies had enrolled 14 customers in the program by summer 1992. One company had achieved 90% of their 2.75 MW bid and the other had achieved less than 90% of their 6.9 MW bid. Critical factors in success were determination of a reasonable bid amount for the market and marketing to the appropriate customers. Customers most interested in the program included those with limited access to capital and medium-sized firms with poor cash flows, particularly schools and hospitals. The findings also show that due to the incentive structure and associated need for substantial customer contributions, lighting measures dominate all installations. Customers, however, were interested in the potential savings and six of the nonparticipants chose to either install measures on their own or enroll in the utility`s rebate program.
Peters, J.S.; Stucky, L.; Seratt, P.; Darden-Butler, D. [Barakat and Chamberlin, Inc., Portland, OR (United States)
Community Action Partnership of Orange County - Weatherization Assistance Program Funds Provided by the American Recovery and Reinvestment Act of 2009, OAS-RA-13-03
Community Action Partnership of Community Action Partnership of Orange County - Weatherization Assistance Program Funds Provided by the American Recovery and Reinvestment Act of 2009 OAS-RA-13-03 October 2012 Department of Energy Washington, DC 20585 October 17, 2012 MEMORANDUM FOR THE ASSISTANT SECRETARY, ENERGY EFFICIENCY AND RENEWABLE ENERGY FROM: Rickey R. Hass Deputy Inspector General for Audit Services Office of Inspector General SUBJECT: INFORMATION: Examination Report on "Community Action Partnership of Orange County - Weatherization Assistance Program Funds Provided by the American Recovery and Reinvestment Act of 2009" BACKGROUND The attached report presents the results of an examination of the Community Action Partnership
A Vista for Microbial Ecology
design alternative energy sources, such as converting algae into biodiesel. Everyday we use energy to integrate renewable energy sources into our electric grid systems that power entire communities. If you price of crude petroleum. 5 #12;Engineering and the Environment For years, Colorado State has taken
Löffler, Frank E.
Nested rollout policy adaptation for Monte Carlo tree search
Monte Carlo tree search (MCTS) methods have had recent success in games, planning, and optimization. MCTS uses results from rollouts to guide search; a rollout is a path that descends the tree with a randomized decision at each ply until reaching a leaf. ...
Christopher D. Rosin
Monte-carlo calculations for some problems of quantum mechanics
The Monte-Carlo technique for the calculations of functional integral in two one-dimensional quantum-mechanical problems had been applied. The energies of the bound states in some potential wells were obtained using this method. Also some peculiarities in the calculation of the kinetic energy in the ground state had been studied.
Novoselov, A. A., E-mail: firstname.lastname@example.com; Pavlovsky, O. V.; Ulybyshev, M. V. [Moscow State University (Russian Federation)
User Manual - Crystal Ball Monte Carlo POD Simulator
This report provides a user manual for a Monte Carlo simulator using Crystal Ball a spreadsheet add-inthat can be used to predict a noise-dependent structural probability of detection (POD) for steam generator tube integrity assessments. The simulator uses plant noise as one of its inputs and provides a plant-specific POD for condition monitoring and operational assessment.
Monte Carlo Simulation of Solar Reflectances for Cloudy Atmospheres
Monte Carlo simulations of solar radiative transfer were performed for a well-resolved, large, three-dimensional (3D) domain of boundary layer cloud simulated by a cloud-resolving model. In order to represent 3D distributions of optical ...
H. W. Barker; R. K. Goldstein; D. E. Stevens
Monte Carlo: in the beginning and some great expectations
The central theme will be on the historical setting and origins of the Monte Carlo Method. The scene was post-war Los Alamos Scientific Laboratory. There was an inevitability about the Monte Carlo Event: the ENIAC had recently enjoyed its meteoric rise (on a classified Los Alamos problem); Stan Ulam had returned to Los Alamos; John von Neumann was a frequent visitor. Techniques, algorithms, and applications developed rapidly at Los Alamos. Soon, the fascination of the Method reached wider horizons. The first paper was submitted for publication in the spring of 1949. In the summer of 1949, the first open conference was held at the University of California at Los Angeles. Of some interst perhaps is an account of Fermi's earlier, independent application in neutron moderation studies while at the University of Rome. The quantum leap expected with the advent of massively parallel processors will provide stimuli for very ambitious applications of the Monte Carlo Method in disciplines ranging from field theories to cosmology, including more realistic models in the neurosciences. A structure of multi-instruction sets for parallel processing is ideally suited for the Monte Carlo approach. One may even hope for a modest hardening of the soft sciences.
Metropolis, N.
Monte Carlo simulation of neutral beam injection into fusion reactors
Motivations and techniques for the Monte Carlo computer simulation of energetic neutral beam injection for fusion reactors are described. The versatility of this approach allows a significantly more sophisticated treatment of charge transfer collision phenomena and consequent effects on engineering design than available from prior work. Exemplary results for a mirror Fusion Engineering Research Facility (FERF) are discussed. (auth)
Miller, R.L.
Forecasting Hotel Arrivals and Occupancy Using Monte Carlo Simulation
Forecasting Hotel Arrivals and Occupancy Using Monte Carlo Simulation Athanasius Zakhary Faculty University, Giza, Egypt (email@example.com) #12;Abstract Forecasting hotel arrivals and occupancy simulation approach for the arrivals and occupancy forecasting problem. In this approach we simulate
Atiya, Amir
Monte Carlo study of self-heating in nanoscale devices
Progress in device miniaturization combined with the increase in integrated circuit packing density, as described by Moore's law, have been accompanied by an exponential increase in on-chip heat generation. In this context, there is an increasing demand ... Keywords: Electron transport, Electrothermal modeling, Monte Carlo, Nanoscale semiconductor devices, Nanowire MISFETs, Self-heating, Si/III-V heterostructure FETs, Thermal transport
Toufik Sadi; Robert W. Kelsall; Neil J. Pilgrim; Jean-Luc Thobel; Fran�ois Dessenne
Monte Carlo algorithms for evaluating Sobol' sensitivity indices
Sensitivity analysis is a powerful technique used to determine robustness, reliability and efficiency of a model. The main problem in this procedure is the evaluating total sensitivity indices that measure a parameter's main effect and all the interactions ... Keywords: Adaptive Monte Carlo algorithm, Global sensitivity indices, Multidimensional numerical integration, Sensitivity analysis
I. Dimov; R. Georgieva
A Monte Carlo electron transport code for the desktop computer
A Monte Carlo electron transport code for the desktop computer is applied to the problem of determining the radiation dose throughout an oblique?surface heterogeneous medium. Absorbed?dose distributions are obtained for 10 MeV electrons incident upon flat?surface and oblique?surface water phantoms
Addendum to �Event-chain Monte Carlo algorithms for hard-sphere systems�
We extend the event-chain Monte Carlo algorithm from hard-sphere interactions to general potentials. This event-driven Monte Carlo algorithm is nonlocal and rejection free and allows for the breaking of detailed balance. ...
Bernard, Etienne
Parallel algorithms for Monte Carlo particle transport simulation on exascale computing architectures
Monte Carlo particle transport methods are being considered as a viable option for high-fidelity simulation of nuclear reactors. While Monte Carlo methods offer several potential advantages over deterministic methods, there ...
Romano, Paul K. (Paul Kollath)
The continuous configurational Boltzmann biased direct Monte Carlo method for free energy properties of polymer chains
We develop here a highly efficient variant of the Monte Carlo method for direct evaluation of the partition function
Jiro Sadanobu; William A. Goddard III
Analysis of communication costs for domain decomposed Monte Carlo methods in nuclear reactor analysis
A domain decomposed Monte Carlo communication kernel is used to carry out performance tests to establish the feasibility of using Monte Carlo techniques for practical Light Water Reactor (LWR) core analyses. The results of the prototype code are interpreted ... Keywords: Monte Carlo, Neutron transport, Performance modeling, Reactor analysis
A. Siegel; K. Smith; P. Fischer; V. Mahadevan
Data decomposition of Monte Carlo particle transport simulations via tally servers
An algorithm for decomposing large tally data in Monte Carlo particle transport simulations is developed, analyzed, and implemented in a continuous-energy Monte Carlo code, OpenMC. The algorithm is based on a non-overlapping decomposition of compute ... Keywords: Data decomposition, Exascale, Monte Carlo, Neutron transport, Tally server
Paul K. Romano, Andrew R. Siegel, Benoit Forget, Kord Smith
Shadow hybrid Monte Carlo: an efficient propagator in phase space of macromolecules
Shadow hybrid Monte Carlo (SHMC) is a new method for sampling the phase space of large molecules, particularly biological molecules. It improves sampling of hybrid Monte Carlo (HMC) by allowing larger time steps and system sizes in the molecular dynamics ... Keywords: conformational sampling, hybrid Monte Carlo, modified Hamiltonian, sampling methods, symplectic integrator
Jes�s A. Izaguirre; Scott S. Hampton
A sequential Monte Carlo/Quantum Mechanics study of the dipole polarizability of liquid benzene
Metropolis Monte Carlo classical simulation and quantum mechanical calculations are performed to obtain the dipole polarizability of liquid benzene. Super-molecular configurations are sampled from NVT Monte Carlo simulation of liquid benzene at room ... Keywords: Monte Carlo simulation, density-functional theory, intermediate-neglect of differential overlap (INDO), liquid benzene, polarizability
Eudes E. Fileti; Sylvio Canuto
Load Balancing Of Parallel Monte Carlo Transport Calculations
Load Balancing Of Parallel Load Balancing Of Parallel Monte Carlo Transport Calculations R.J. Procassini, M. J. O'Brien and J.M. Taylor Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA 94551 The performance of parallel Monte Carlo transport calculations which use both spatial and particle parallelism is increased by dynamically assigning processors to the most worked domains. Since the particle work load varies over the course of the simulation, each cycle this algorithm determines if dynamic load balancing would speed up the calculation. If load balancing is required, a small number of particle communications are initiated in order to achieve load balance. This method has decreased the parallel run time by more than a factor of three for certain criticality
The dynamics of quantum criticality: Quantum Monte Carlo and holography
Understanding the real time dynamics of systems near quantum critical points at non-zero temperatures constitutes an important yet challenging problem, especially in two spatial dimensions where interactions are strong. We present detailed quantum Monte Carlo results for two separate realizations of the superfluid-insulator transition of bosons on a lattice: their low-frequency conductivities are found to have the same universal dependence on imaginary frequency and temperature. We then use the structure of the real time dynamics of conformal field theories described by the holographic gauge/gravity duality to make progress on the difficult problem of analytically continuing the Monte Carlo data to real time. Our method yields quantitative and experimentally testable results on the frequency-dependent conductivity at the quantum critical point, and on the spectrum of quasinormal modes in the vicinity of the superfluid-insulator quantum phase transition. Extensions to other observables and universality classes are discussed.
William Witczak-Krempa; Erik Sorensen; Subir Sachdev
Ab initio Monte Carlo investigation of small lithium clusters.
Structural and thermal properties of small lithium clusters are studied using ab initio-based Monte Carlo simulations. The ab initio scheme uses a Hartree-Fock/density functional treatment of the electronic structure combined with a jump-walking Monte Carlo sampling of nuclear configurations. Structural forms of Li{sub 8} and Li{sub 9}{sup +} clusters are obtained and their thermal properties analyzed in terms of probability distributions of the cluster potential energy, average potential energy and configurational heat capacity all considered as a function of the cluster temperature. Details of the gradual evolution with temperature of the structural forms sampled are examined. Temperatures characterizing the onset of structural changes and isomer coexistence are identified for both clusters.
Srinivas, S.
Quantum Monte Carlo with Coupled-Cluster wave functions
We introduce a novel many body method which combines two powerful many body techniques, viz., quantum Monte Carlo and coupled cluster theory. Coupled cluster wave functions are introduced as importance functions in a Monte Carlo method designed for the configuration interaction framework to provide rigorous upper bounds to the ground state energy. We benchmark our method on the homogeneous electron gas in momentum space. The importance function used is the coupled cluster doubles wave function. We show that the computational resources required in our method scale polynomially with system size. Our energy upper bounds are in very good agreement with previous calculations of similar accuracy, and they can be systematically improved by including higher order excitations in the coupled cluster wave function.
Roggero, Alessandro; Pederiva, Francesco
Alessandro Roggero; Abhishek Mukherjee; Francesco Pederiva
Monte Carlo Simulations of Neutron Oil well Logging Tools
Monte Carlo simulations of simple neutron oil well logging tools into typical geological formations are presented.The simulated tools consist of both 14 MeV pulsed and continuous Am-Be neutron sources with time gated and continuous gamma ray detectors respectively.The geological formation consists of pure limestone with 15% absolute porosity in a wide range of oil saturation.The particle transport was performed with the Monte Carlo N-Particle Transport Code System, MCNP-4B.Several gamma ray spectra were obtained at the detector position that allow to perform composition analysis of the formation.In particular, the ratio C/O was analyzed as an indicator of oil saturation.Further calculations are proposed to simulate actual detector responses in order to contribute to understand the relation between the detector response with the formation composition
Azcurra, M
MC++: Parallel, portable, Monte Carlo neutron transport in C++
We have developed an implicit Monte Carlo neutron transport code in C++ using the Parallel Object-Oriented Methods and Applications (POOMA) class library. MC++ runs in parallel on and is portable to a wide variety of platforms, including MPPs, clustered SMPs, and individual workstations. It contains appropriate classes and abstractions for particle transport and parallelism. Current capabilities of MC++ are discussed, along with future plans and physics and performance results on many different platforms.
Lee, S.R.; Cummings, J.C. [Los Alamos National Lab., NM (United States); Nolen, S.D. [Texas A& M Univ., College Station, TX (United States). Dept. of Nuclear Engineering
Towards a Revised Monte Carlo Neutral Particle Surface Interaction Model
The components of the neutral- and plasma-surface interaction model used in the Monte Carlo neutral transport code DEGAS 2 are reviewed. The idealized surfaces and processes handled by that model are inadequate for accurately simulating neutral transport behavior in present day and future fusion devices. We identify some of the physical processes missing from the model, such as mixed materials and implanted hydrogen, and make some suggestions for improving the model.
D.P. Stotler
Multi-Determinant Wave-functions in Quantum Monte Carlo
Quantum Monte Carlo methods have received considerable attention over the last decades due to the great promise they have for the direct solution to the many-body Schrodinger equation for electronic systems. Thanks to a low scaling with number of particles, they present one of the best alternatives in the accurate study of large systems and solid state calculations. In spite of such promise, the method has not become popular in the quantum chemistry community, mainly due to the lack of control over the fixed-node error which can be large in many cases. In this article we present the application of large multi-determinant expansions in quantum Monte Carlo, studying its performance with first row dimers and the 55 molecules of the G1 test set. We demonstrate the potential of the wave-function to systematically reduce the fixed-node error in the calculations, achieving chemical accuracy in almost all cases studied. When compared to traditional methods in quantum chemistry, the results show a marked improvement over most methods including MP2, CCSD(T) and DFT with various functionals; in fact the only method able to produce better results is the explicitly-correlated CCSD(T) method with a large basis set. With recent developments in trial wave functions and algorithmic improvements in Quantum Monte Carlo, we are quickly approaching a time where the method can become the standard in the study of large molecular systems and solids.
Morales, Miguel A [Lawrence Livermore National Laboratory (LLNL); Mcminis, Jeremy [University of Illinois, Urbana-Champaign; Clark, Bryan K. [Princeton University; Kim, Jeongnim [ORNL; Scuseria, Gustavo E [Rice University
Coupled MHD-Monte Carlo transport model for dense plasmas
A two-dimensional, two fluid model of the MHD equations has been coupled to a Monte Carlo transport model of high energy, non-Maxwellian ions. The MHD part of the model assumes complete ionization and includes a perfect gas law for a scalar pressure, a tensor artificial viscosity, electron and ion thermal conduction, electron-ion coupling, and a radiation loss term. A simple Ohm's Law is used with a B/sub theta/ magnetic field. The MHD equations were solved in Lagrangian coordinates. The conservation equations were differenced explicitly and the diffusion-type equations implicitly using the splitting technique. The Monte Carlo model solves the equation of motion for high energy ions, moving through and suffering small and large angle collisions with the fluid Maxwellian plasma. The source of high energy ions is the thermonuclear reactions of the hydrogen isotopes, or it may be an externally injected beam of neutralized ions. In addition to using the usual Maxwell averaged thermonuclear cross sections for calculating the number of reactions taking place within the Maxwellian plasma, the high energy ions may suffer collisions resulting in a reaction. In the Monte Carlo model all neutrons are assumed to escape, and all energetic ions of Z less than or equal to 2 are followed. (auth)
Chandler, W.P.
Kinetic Lattice Monte Carlo Simulation ofKinetic Lattice Monte Carlo Simulation of Polycrystalline Thin film growthPolycrystalline Thin film growth
grain orientations s The first application of this code is to the growth of Mo tips, including chemicalKinetic Lattice Monte Carlo Simulation ofKinetic Lattice Monte Carlo Simulation of Polycrystalline Applications Motorola National Science Foundation National Center for Supercomputer Applications Motorola #12
Adams, James B
Continuous-Estimator Representation for Monte Carlo Criticality Diagnostics
An alternate means of computing diagnostics for Monte Carlo criticality calculations is proposed. Overlapping spherical regions or estimators are placed covering the fissile material with a minimum center-to-center separation of the 'fission distance', which is defined herein, and a radius that is some multiple thereof. Fission neutron production is recorded based upon a weighted average of proximities to centers for all the spherical estimators. These scores are used to compute the Shannon entropy, and shown to reproduce the value, to within an additive constant, determined from a well-placed mesh by a user. The spherical estimators are also used to assess statistical coverage.
Kiedrowski, Brian C. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory
Process Characterisation with Monte-Carlo Wave-Functions
We present a numerically efficient method for the characterisation of a quantum process subject to dissipation and noise. The master equation evolution of a maximally entangled state of the quantum system and a non-evolving ancilla system is simulated by Monte-Carlo wave-functions. We show how each stochastic state vectors provides quantities that are readily combined into an average process \\chi-matrix. Our method significantly reduces the computational complexity in comparison with standard characterisation methods. It also readily provides an upper bound on the trace distance between the ideal and simulated process based on the evolution of only a single wave function of the entangled system.
Jake Gulliksen; D. D. Bhaktavatsala Rao; Klaus M�lmer
Bounded limit for the Monte Carlo point-flux-estimator
In a Monte Carlo random walk the kernel K(R,E) is used as an expected value estimator at every collision for the collided flux phi/sub c/ r vector,E) at the detector point. A limiting value for the kernel is derived from a diffusion approximation for the probability current at a radius R/sub 1/ from the detector point. The variance of the collided flux at the detector point is thus bounded using this asymptotic form for K(R,E). The bounded point flux estimator is derived. (WHK)
Grimesey, R.A.
Adaptively Learning an Importance Function Using Transport Constrained Monte Carlo
It is well known that a Monte Carlo estimate can be obtained with zero-variance if an exact importance function for the estimate is known. There are many ways that one might iteratively seek to obtain an ever more exact importance function. This paper describes a method that has obtained ever more exact importance functions that empirically produce an error that is dropping exponentially with computer time. The method described herein constrains the importance function to satisfy the (adjoint) Boltzmann transport equation. This constraint is provided by using the known form of the solution, usually referred to as the Case eigenfunction solution.
Validation of Phonon Physics in the CDMS Detector Monte Carlo
The SuperCDMS collaboration is a dark matter search effort aimed at detecting the scattering of WIMP dark matter from nuclei in cryogenic germanium targets. The CDMS Detector Monte Carlo (CDMS-DMC) is a simulation tool aimed at achieving a deeper understanding of the performance of the SuperCDMS detectors and aiding the dark matter search analysis. We present results from validation of the phonon physics described in the CDMS-DMC and outline work towards utilizing it in future WIMP search analyses.
McCarthy, K.A.; Leman, S.W.; Anderson, A.J.; /MIT; Brandt, D.; /SLAC; Brink, P.L.; Cabrera, B.; Cherry, M.; /Stanford U.; Do Couto E Silva, E.; /SLAC; Cushman, P.; /Minnesota U.; Doughty, T.; /UC, Berkeley; Figueroa-Feliciano, E.; /MIT; Kim, P.; /SLAC; Mirabolfathi, N.; /UC, Berkeley; Novak, L.; /Stanford U.; Partridge, R.; /SLAC; Pyle, M.; /Stanford U.; Reisetter, A.; /Minnesota U. /St. Olaf Coll.; Resch, R.; /SLAC; Sadoulet, B.; Serfass, B.; Sundqvist, K.M.; /UC, Berkeley /Stanford U.
An alternative Monte Carlo approach to the thermal radiative transfer problem
The usual Monte Carlo approach to the thermal radiative transfer problem is to view Monte Carlo as a solution technique for the nonlinear thermal radiative transfer equations. The equations contain time derivatives which are approximated by introducing small time steps. An alternative approach avoids time steps by using Monte Carlo to directly sample the time at which the next event occurs. That is, the time is advanced on a natural event-by-event basis rather than by introducing an artificial time step.
Booth, Thomas E., E-mail: firstname.lastname@example.com [Mail Stop A143, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
EA-1841: Department of Energy Loan Guarantee for the Taylor Biomass Montgomery Project in the Town of Montgomery, Orange County, New York
Taylor Biomass, LLC (Taylor) submitted an application to DOE for a Federal loan guarantee to support the construction and startup of a biomass gasification-to energy facility at a 95-acre recycling facility in the Town of Montgomery, Orange County, NY. The Project would involve the construction of a Post-Collection Separation Facility, a Gasification System and a Combined Cycle Gas Turbine Power Island.
Observations of the formation and maintenance of beach cusps on Del Monte Beach in Monterey, California .
??During the period of 5 April 2001 - 16 May 2001, topographic surveys of Del Monte beach in Monterey, California, were performed on a regular� (more)
Miller, Gregory Chad.
MINT: a Computer Program for Adaptive Monte Carlo Integration and Generation of Unweighted Distributions
In this note I illustrate the program MINT, a FORTRAN program for Monte Carlo adaptive integration and generation of unweighted distributions.
Nason, P
P. Nason
Avalia��o s�cio-econ�mica e ambiental do complexo hidrel�trico de Belo Monte.
??O presente trabalho tem como objetivo tratar da constru��o do Complexo Hidrel�trico de Belo Monte, trazendo informa��es sobre aspectos econ�micos, de produ��o e consumo energ�tico.� (more)
Neidja Cristine Silvestre Leit�o
Identification and confirmation of molecular markers and orange flesh color associated with major QTL for high beta-carotene content in muskmelon
Beta-carotene presence or absence in muskmelon is controlled by two genes, green flesh gf and white flesh wf. In its dominant form the wf gene is responsible for orange flesh color; however, the epistatic interactions of gf and wf can create three flesh colors: orange, white and green. Two F2 populations, consisting of 77 greenhouse grown and 117 field grown plants, from the cross of �Sunrise� (white fleshed) by �TAM Uvalde� (orange fleshed), were used to examine the relationships of beta-carotene content, flesh color, and flesh color intensity. Bulk segregent analysis was used with RAPD markers to identify molecular markers associated with high beta-carotene content. Flesh color and flesh color intensity both had significant relationships with beta-carotene content. A significant correlation between total soluble solids and beta-carotene content was also found. Molecular markers were identified in both F2 populations and all significant, associated markers from �TAM Uvalde� were linked with WF. A single QTL was also found to be linked with the WF locus. The identified QTL can be used to screen potential breeding lines for high beta-carotene. It was also confirmed that the visual ratings of flesh color intensity can be reliably used to select high beta-carotene content melons.
Napier, Alexandra Bamberger
Monte Carlo parameter studies and uncertainty analyses with MCNP5
A software tool called mcnp-pstudy has been developed to automate the setup, execution, and collection of results from a series of MCNPS Monte Carlo calculations. This tool provides a convenient means of performing parameter studies, total uncertainty analyses, parallel job execution on clusters, stochastic geometry modeling, and other types of calculations where a series of MCNPS jobs must be performed with varying problem input specifications. Monte Carlo codes are being used for a wide variety of applications today due to their accurate physical modeling and the speed of today's computers. In most applications for design work, experiment analysis, and benchmark calculations, it is common to run many calculations, not just one, to examine the effects of design tolerances, experimental uncertainties, or variations in modeling features. We have developed a software tool for use with MCNP5 to automate this process. The tool, mcnp-pstudy, is used to automate the operations of preparing a series of MCNP5 input files, running the calculations, and collecting the results. Using this tool, parameter studies, total uncertainty analyses, or repeated (possibly parallel) calculations with MCNP5 can be performed easily. Essentially no extra user setup time is required beyond that of preparing a single MCNP5 input file.
Brown, F. B. (Forrest B.); Sweezy, J. E. (Jeremy E.); Hayes, R. B. (Robert B.)
A First-Passage Kinetic Monte Carlo algorithm for complex diffusion-reaction systems
We develop an asynchronous event-driven First-Passage Kinetic Monte Carlo (FPKMC) algorithm for continuous time and space systems involving multiple diffusing and reacting species of spherical particles in two and three dimensions. The FPKMC algorithm ... Keywords: Asynchronous algorithms, Diffusion-reaction, First-passage, Kinetic Monte Carlo
Aleksandar Donev; Vasily V. Bulatov; Tomas Oppelstrup; George H. Gilmer; Babak Sadigh; Malvin H. Kalos
Sequential Monte Carlo for Bayesian sequentially designed experiments for discrete data
In this paper we present a sequential Monte Carlo algorithm for Bayesian sequential experimental design applied to generalised non-linear models for discrete data. The approach is computationally convenient in that the information of newly observed data ... Keywords: Clinical trials, Generalised linear model, Generalised non-linear model, Sequential Monte Carlo, Sequential design, Target stimulus
Christopher C. Drovandi; James M. Mcgree; Anthony N. Pettitt
Monte Carlo modeling of spin FETs controlled by spin-orbit interaction
A method for Monte Carlo simulation of 2D spin-polarized electron transport in III-V semiconductor heterojunction (FETs) is presented. In the simulation, the dynamics of the electrons in coordinate and momentum space is treated semiclassically. The density ... Keywords: FET, Monte Carlo, spin orbit, spintronics
Min Shen; Semion Saikin; Ming-C. Cheng; Vladimir Privman
Using Monte-Carlo simulation for risk assessment: application to occupational exposure during remediation works
The aim of this study was to apply the Monte-Carlo techniques to develop a probabilistic risk assessment. The risk resulting from the occupational exposure during the remediation activities of a uranium tailings disposal, in an abandoned uranium mining ... Keywords: Monte Carlo simulation, occupational exposure, risk and dose assessment, uranium tailings disposal
M. L. Dinis; A. Fi�za
Asymptotic diffusion limit of the symbolic Monte-Carlo method for the transport equation
We use asymptotic analysis to study the diffusion limit of the Symbolic Implicit Monte-Carlo (SIMC) method for the transport equation. For standard SIMC with piecewise constant basis functions, we demonstrate mathematically that the solution converges ... Keywords: Monte-Carlo method, radiative transfer
J.-F. Clou�t; G. Samba
Methods for coupling radiation, ion, and electron energies in grey Implicit Monte Carlo
We present three methods for extending the Implicit Monte Carlo (IMC) method to treat the time-evolution of coupled radiation, electron, and ion energies. The first method splits the ion and electron coupling and conduction from the standard IMC radiation-transport ... Keywords: Implicit Monte Carlo, Thermal radiation transport, Three-temperature model
T. M. Evans; J. D. Densmore
A comparison of generalized hybrid Monte Carlo methods with and without momentum flip
The generalized hybrid Monte Carlo (GHMC) method combines Metropolis corrected constant energy simulations with a partial random refreshment step in the particle momenta. The standard detailed balance condition requires that momenta are negated upon ... Keywords: Langevin dynamics, Molecular dynamics, Monte Carlo methods, Sampling
Elena Akhmatskaya; Nawaf Bou-Rabee; Sebastian Reich
An efficient, robust, domain-decomposition algorithm for particle Monte Carlo
A previously described algorithm [T.A. Brunner, T.J. Urbatsch, T.M. Evans, N.A. Gentile, Comparison of four parallel algorithms for domain decomposed implicit Monte Carlo, Journal of Computational Physics 212 (2) (2006) 527-539] for doing domain decomposed ... Keywords: Monte Carlo methods, Neutron transport, Parallel computation, Radiative transfer
Thomas A. Brunner; Patrick S. Brantley
Monte Carlo Simulation Tool Installation and Operation Guide
This document provides information on software and procedures for Monte Carlo simulations based on the Geant4 toolkit, the ROOT data analysis software and the CRY cosmic ray library. These tools have been chosen for its application to shield design and activation studies as part of the simulation task for the Majorana Collaboration. This document includes instructions for installation, operation and modification of the simulation code in a high cyber-security computing environment, such as the Pacific Northwest National Laboratory network. It is intended as a living document, and will be periodically updated. It is a starting point for information collection by an experimenter, and is not the definitive source. Users should consult with one of the authors for guidance on how to find the most current information for their needs.
Aguayo Navarrete, Estanislao; Ankney, Austin S.; Berguson, Timothy J.; Kouzes, Richard T.; Orrell, John L.; Troy, Meredith D.; Wiseman, Clinton G.
Quantum Monte Carlo (QMC) methods have received considerable attention over the last decades due to their great promise for providing a direct solution to the many-body Schrodinger equation in electronic systems. Thanks to their low scaling with number of particles, QMC methods present a compelling competitive alternative for the accurate study of large molecular systems and solid state calculations. In spite of such promise, the method has not permeated the quantum chemistry community broadly, mainly because of the fixed-node error, which can be large and whose control is difficult. In this Perspective, we present a systematic application of large scale multi-determinant expansions in QMC, and report on its impressive performance with first row dimers and the 55 molecules of the G1 test set. We demonstrate the potential of this strategy for systematically reducing the fixed-node error in the wave function and for achieving chemical accuracy in energy predictions. When compared to traditional quantum chemistr...
Morales, M A; Clark, B K; Kim, J; Scuseria, G; 10.1021/ct3003404
Optimization of Monte Carlo transport simulations in stochastic media
This paper presents an accurate and efficient approach to optimize radiation transport simulations in a stochastic medium of high heterogeneity, like the Very High Temperature Gas-cooled Reactor (VHTR) configurations packed with TRISO fuel particles. Based on a fast nearest neighbor search algorithm, a modified fast Random Sequential Addition (RSA) method is first developed to speed up the generation of the stochastic media systems packed with both mono-sized and poly-sized spheres. A fast neutron tracking method is then developed to optimize the next sphere boundary search in the radiation transport procedure. In order to investigate their accuracy and efficiency, the developed sphere packing and neutron tracking methods are implemented into an in-house continuous energy Monte Carlo code to solve an eigenvalue problem in VHTR unit cells. Comparison with the MCNP benchmark calculations for the same problem indicates that the new methods show considerably higher computational efficiency. (authors)
Liang, C.; Ji, W. [Dept. of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Inst., 110 8th street, Troy, NY (United States)
The Quantum Energy Density: Improved Efficiency for Quantum Monte Carlo
We establish a physically meaningful representation of a quantum energy density for use in Quantum Monte Carlo calculations. The energy density operator, defined in terms of Hamiltonian components and density operators, returns the correct Hamiltonian when integrated over a volume containing a cluster of particles. This property is demonstrated for a helium-neon "gas," showing that atomic energies obtained from the energy density correspond to eigenvalues of isolated systems. The formation energies of defects or interfaces are typically calculated as total energy differences. Using a model of delta-doped silicon (where dopant atoms form a thin plane) we show how interfacial energies can be calculated more efficiently with the energy density, since the region of interest is small. We also demonstrate how the energy density correctly transitions to the bulk limit away from the interface where the correct energy is obtainable from a separate total energy calculation.
Krogel, Jaron T; Kim, Jeongnim; Ceperley, David M
Bayesian Inference in Monte-Carlo Tree Search
Monte-Carlo Tree Search (MCTS) methods are drawing great interest after yielding breakthrough results in computer Go. This paper proposes a Bayesian approach to MCTS that is inspired by distributionfree approaches such as UCT [13], yet significantly differs in important respects. The Bayesian framework allows potentially much more accurate (Bayes-optimal) estimation of node values and node uncertainties from a limited number of simulation trials. We further propose propagating inference in the tree via fast analytic Gaussian approximation methods: this can make the overhead of Bayesian inference manageable in domains such as Go, while preserving high accuracy of expected-value estimates. We find substantial empirical outperformance of UCT in an idealized bandit-tree test environment, where we can obtain valuable insights by comparing with known ground truth. Additionally we rigorously prove on-policy and off-policy convergence of the proposed methods.
Tesauro, Gerald; Segal, Richard
Correlated wavefunction quantum Monte Carlo approach to solids
A method for calculating the electronic and structural properties of solids using correlated wavefunctions together with quantum Monte Carlo techniques is described. The approach retains the exact Coulomb interaction between the electrons and employs a many-electron wavefunction of the Jastrow-Slater form. Several examples are given to illustrate the utility of the method. Topics discussed include the cohesive properties of bulk semiconductors, the magnetic-field- induced Wigner crystal in two dimensions, and the magnetic structure of bcc hydrogen. Landau level mixing is shown to be important in determining the transition between the fractional quantum Hall liquid and the Wigner crystal. Information on electron correlations such as the pair correlation functions which are not accessible to one- electron theories is also obtained. 24 refs, 5 figs, 1 tab.
Louie, S.G.
Soci t d exploitation du parc olien de Mont d H z cques SARL | Open Energy
Soci t d exploitation du parc olien de Mont d H z cques SARL Soci t d exploitation du parc olien de Mont d H z cques SARL Jump to: navigation, search Name Société d'exploitation du parc éolien de Mont d'Hézècques SARL Place Madrid, Spain Sector Wind energy Product Special purpose vehicle for French wind farm project development. References Société d'exploitation du parc éolien de Mont d'Hézècques SARL[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Société d'exploitation du parc éolien de Mont d'Hézècques SARL is a company located in Madrid, Spain . References ↑ "[ Société d'exploitation du parc éolien de Mont d'Hézècques SARL]" Retrieved from "http://en.openei.org/w/index.php?title=Soci_t_d_exploitation_du_parc_olien_de_Mont_d_H_z_cques_SARL&oldid=351211
Quantum Monte Carlo for electronic structure: Recent developments and applications
Quantum Monte Carlo (QMC) methods have been found to give excellent results when applied to chemical systems. The main goal of the present work is to use QMC to perform electronic structure calculations. In QMC, a Monte Carlo simulation is used to solve the Schroedinger equation, taking advantage of its analogy to a classical diffusion process with branching. In the present work the author focuses on how to extend the usefulness of QMC to more meaningful molecular systems. This study is aimed at questions concerning polyatomic and large atomic number systems. The accuracy of the solution obtained is determined by the accuracy of the trial wave function`s nodal structure. Efforts in the group have given great emphasis to finding optimized wave functions for the QMC calculations. Little work had been done by systematically looking at a family of systems to see how the best wave functions evolve with system size. In this work the author presents a study of trial wave functions for C, CH, C{sub 2}H and C{sub 2}H{sub 2}. The goal is to study how to build wave functions for larger systems by accumulating knowledge from the wave functions of its fragments as well as gaining some knowledge on the usefulness of multi-reference wave functions. In a MC calculation of a heavy atom, for reasonable time steps most moves for core electrons are rejected. For this reason true equilibration is rarely achieved. A method proposed by Batrouni and Reynolds modifies the way the simulation is performed without altering the final steady-state solution. It introduces an acceleration matrix chosen so that all coordinates (i.e., of core and valence electrons) propagate at comparable speeds. A study of the results obtained using their proposed matrix suggests that it may not be the optimum choice. In this work the author has found that the desired mixing of coordinates between core and valence electrons is not achieved when using this matrix. A bibliography of 175 references is included.
Rodriguez, M.M.S. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Chemical Sciences Div.
Monte Carlo simulations for generic granite repository studies
In a collaborative study between Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) for the DOE-NE Office of Fuel Cycle Technologies Used Fuel Disposition (UFD) Campaign project, we have conducted preliminary system-level analyses to support the development of a long-term strategy for geologic disposal of high-level radioactive waste. A general modeling framework consisting of a near- and a far-field submodel for a granite GDSE was developed. A representative far-field transport model for a generic granite repository was merged with an integrated systems (GoldSim) near-field model. Integrated Monte Carlo model runs with the combined near- and farfield transport models were performed, and the parameter sensitivities were evaluated for the combined system. In addition, a sub-set of radionuclides that are potentially important to repository performance were identified and evaluated for a series of model runs. The analyses were conducted with different waste inventory scenarios. Analyses were also conducted for different repository radionuelide release scenarios. While the results to date are for a generic granite repository, the work establishes the method to be used in the future to provide guidance on the development of strategy for long-term disposal of high-level radioactive waste in a granite repository.
Chu, Shaoping [Los Alamos National Laboratory; Lee, Joon H [SNL; Wang, Yifeng [SNL
Non-analog Monte Carlo estimators for radiation momentum deposition
The standard method for calculating radiation momentum deposition in Monte Carlo simulations is the analog estimator, which tallies the change in a particle's momentum at each interaction with the matter. Unfortunately, the analog estimator can suffer from large amounts of statistical error. In this paper, we present three new non-analog techniques for estimating momentum deposition. Specifically, we use absorption, collision, and track-length estimators to evaluate a simple integral expression for momentum deposition that does not contain terms that can cause large amounts of statistical error in the analog scheme. We compare our new non-analog estimators to the analog estimator with a set of test problems that encompass a wide range of material properties and both isotropic and anisotropic scattering. In nearly all cases, the new non-analog estimators outperform the analog estimator. The track-length estimator consistently yields the highest performance gains, improving upon the analog-estimator figure of merit by factors of up to two orders of magnitude.
Densmore, Jeffery D [Los Alamos National Laboratory; Hykes, Joshua M [Los Alamos National Laboratory
Monte Carlo Simulations of Cosmic Rays Hadronic Interactions
This document describes the construction and results of the MaCoR software tool, developed to model the hadronic interactions of cosmic rays with different geometries of materials. The ubiquity of cosmic radiation in the environment results in the activation of stable isotopes, referred to as cosmogenic activities. The objective is to use this application in conjunction with a model of the MAJORANA DEMONSTRATOR components, from extraction to deployment, to evaluate cosmogenic activation of such components before and after deployment. The cosmic ray showers include several types of particles with a wide range of energy (MeV to GeV). It is infeasible to compute an exact result with a deterministic algorithm for this problem; Monte Carlo simulations are a more suitable approach to model cosmic ray hadronic interactions. In order to validate the results generated by the application, a test comparing experimental muon flux measurements and those predicted by the application is presented. The experimental and simulated results have a deviation of 3%.
Aguayo Navarrete, Estanislao; Orrell, John L.; Kouzes, Richard T.
Numerical study of error propagation in Monte Carlo depletion simulations
Improving computer technology and the desire to more accurately model the heterogeneity of the nuclear reactor environment have made the use of Monte Carlo depletion codes more attractive in recent years, and feasible (if not practical) even for 3-D depletion simulation. However, in this case statistical uncertainty is combined with error propagating through the calculation from previous steps. In an effort to understand this error propagation, a numerical study was undertaken to model and track individual fuel pins in four 17 x 17 PWR fuel assemblies. By changing the code's initial random number seed, the data produced by a series of 19 replica runs was used to investigate the true and apparent variance in k{sub eff}, pin powers, and number densities of several isotopes. While this study does not intend to develop a predictive model for error propagation, it is hoped that its results can help to identify some common regularities in the behavior of uncertainty in several key parameters. (authors)
Wyant, T.; Petrovic, B. [Nuclear and Radiological Engineering, Georgia Inst. of Technology, 770 State Street, Atlanta, GA 30332-0745 (United States)
Reduced Variance for Material Sources in Implicit Monte Carlo
Implicit Monte Carlo (IMC), a time-implicit method due to Fleck and Cummings, is used for simulating supernovae and inertial confinement fusion (ICF) systems where x-rays tightly and nonlinearly interact with hot material. The IMC algorithm represents absorption and emission within a timestep as an effective scatter. Similarly, the IMC time-implicitness splits off a portion of a material source directly into the radiation field. We have found that some of our variance reduction and particle management schemes will allow large variances in the presence of small, but important, material sources, as in the case of ICF hot electron preheat sources. We propose a modification of our implementation of the IMC method in the Jayenne IMC Project. Instead of battling the sampling issues associated with a small source, we bypass the IMC implicitness altogether and simply deterministically update the material state with the material source if the temperature of the spatial cell is below a user-specified cutoff. We describe the modified method and present results on a test problem that show the elimination of variance for small sources.
Urbatsch, Todd J. [Los Alamos National Laboratory
A Monte Carlo Approach To Generator Portfolio Planning And Carbon Emissions
Monte Carlo Approach To Generator Portfolio Planning And Carbon Emissions Monte Carlo Approach To Generator Portfolio Planning And Carbon Emissions Assessments Of Systems With Large Penetrations Of Variable Renewables Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A Monte Carlo Approach To Generator Portfolio Planning And Carbon Emissions Assessments Of Systems With Large Penetrations Of Variable Renewables Details Activities (0) Areas (0) Regions (0) Abstract: A new generator portfolio planning model is described that is capable of quantifying the carbon emissions associated with systems that include very high penetrations of variable renewables. The model combines a deterministic renewable portfolio planning module with a Monte Carlo simulation of system operation that determines the expected least-cost
Mountain Waves over Mont Blanc: Influence of a Stagnant Boundary Layer
A stationary mountain wave, embedded in southwesterly flow over Mont Blanc in the Alps, was observed simultaneously by three research aircraft and three types of remote sensing: GPS dropsondes, airborne light detecting and ranging (lidar), and ...
Ronald B. Smith; Steven Skubis; James D. Doyle; Adrian S. Broad; Christoph Kiemle; Hans Volkert
MERADGEN: Monte Carlo generator for the simulation of radiative events in polarized Moller scattering
The Monte Carlo generator MERADGEN for the simulation of QED radiative events in polarized Moller scattering has been developed. Analytical integration wherever it is possible provides rather fast generation. Some numerical tests and histograms are presented.
Andrei Afanasev; Eugene Chudakov; Alexander Ilyichev; Vladimir Zykunov
Monte Carlo simulation model for electromagnetic scattering from vegetation and inversion of vegetation parameters
In this thesis research, a coherent scattering model for microwave remote sensing of vegetation canopy is developed on the basis of Monte Carlo simulations. An accurate model of vegetation structure is essential for the ...
Wang, Li-Fang, Ph. D. Massachusetts Institute of Technology
Remote Sounding of High Clouds. III: Monte Carlo Calculations of Multiple-Scattered Lidar Returns
Monte Carlo calculations of multiple-scattered contributions to the total energy received in a lidar beam have been made for a representative cirrus ice-cloud scattering phase function. The phase function is varied arbitrarily near the back ...
C. M. R. Platt
Estimation of Wind Speed Distribution Using Markov Chain Monte Carlo Techniques
The Weibull distribution is the most commonly used statistical distribution for describing wind speed data. Maximum likelihood has traditionally been the main method of estimation for Weibull parameters. In this paper, Markov chain Monte Carlo ...
Wan-Kai Pang; Jonathan J. Forster; Marvin D. Troutt
Nonlinear Parameter Estimation: Comparison of an Ensemble Kalman Smoother with a Markov Chain Monte Carlo Algorithm
This paper explores the temporal evolution of cloud microphysical parameter uncertainty using an idealized 1D model of deep convection. Model parameter uncertainty is quantified using a Markov chain Monte Carlo (MCMC) algorithm. A new form of the ...
Derek J. Posselt; Craig H. Bishop
Time-domain non-Monte Carlo noise simulation for nonlinear dynamic circuits with arbitrary excitations
A new, time-domain, non-Monte Carlo method for computer simulation of electrical noise in nonlinear dynamic circuits with arbitrary excitations is presented. This time-domain noise simulation ...
Alper Demir; Edward W. Y. Liu; Alberto L. Sangiovanni-Vincentelli
Clustering and Short-Range Orer in Fe-Cr Alloys: A Monte Carlo Study
May 1, 2007 ... Clustering and Short-Range Orer in Fe-Cr Alloys: A Monte Carlo Study by Mikhail Lavrentiev, Duc Nguyen-Manh, Sergei Dudarev, Ralf Drautz,�...
PyMercury: Interactive Python for the Mercury Monte Carlo Particle Transport Code
Monte Carlo particle transport applications are often written in low-level languages (C/C++) for optimal performance on clusters and supercomputers. However, this development approach often sacrifices straightforward usability and testing in the interest of fast application performance. To improve usability, some high-performance computing applications employ mixed-language programming with high-level and low-level languages. In this study, we consider the benefits of incorporating an interactive Python interface into a Monte Carlo application. With PyMercury, a new Python extension to the Mercury general-purpose Monte Carlo particle transport code, we improve application usability without diminishing performance. In two case studies, we illustrate how PyMercury improves usability and simplifies testing and validation in a Monte Carlo application. In short, PyMercury demonstrates the value of interactive Python for Monte Carlo particle transport applications. In the future, we expect interactive Python to play an increasingly significant role in Monte Carlo usage and testing.
Iandola, F N; O'Brien, M J; Procassini, R J
Novel Hybrid Monte Carlo/Deterministic Technique for Shutdown Dose Rate Analyses of Fusion Energy Systems
The rigorous 2-step (R2S) method uses three-dimensional Monte Carlo transport simulations to calculate the shutdown dose rate (SDDR) in fusion reactors. Accurate full-scale R2S calculations are impractical in fusion reactors because they require calculating space- and energy-dependent neutron fluxes everywhere inside the reactor. The use of global Monte Carlo variance reduction techniques was suggested for accelerating the neutron transport calculation of the R2S method. The prohibitive computational costs of these approaches, which increase with the problem size and amount of shielding materials, inhibit their use in the accurate full-scale neutronics analyses of fusion reactors. This paper describes a novel hybrid Monte Carlo/deterministic technique that uses the Consistent Adjoint Driven Importance Sampling (CADIS) methodology but focuses on multi-step shielding calculations. The Multi-Step CADIS (MS-CADIS) method speeds up the Monte Carlo neutron calculation of the R2S method using an importance function that represents the importance of the neutrons to the final SDDR. Using a simplified example, preliminarily results showed that the use of MS-CADIS enhanced the efficiency of the neutron Monte Carlo simulation of an SDDR calculation by a factor of 550 compared to standard global variance reduction techniques, and that the increase over analog Monte Carlo is higher than 10,000.
Ibrahim, Ahmad M [ORNL; Peplow, Douglas E. [ORNL; Peterson, Joshua L [ORNL; Grove, Robert E [ORNL
Monte Carlo approaches to radiation transport have several attractive properties such as simplicity of implementation, high accuracy, and good parallel scaling. Moreover, Monte Carlo methods can handle complicated geometries and are relatively easy to extend to multiple spatial dimensions, which makes them potentially interesting in modeling complex multi-dimensional astrophysical phenomena such as core-collapse supernovae. The aim of this paper is to explore Monte Carlo methods for modeling neutrino transport in core-collapse supernovae. We generalize the Implicit Monte Carlo photon transport scheme of Fleck and Cummings and gray discrete-diffusion scheme of Densmore et al. to energy-, time-, and velocity-dependent neutrino transport. Using our 1D spherically-symmetric implementation, we show that, similar to the photon transport case, the implicit scheme enables significantly larger timesteps compared with explicit time discretization, without sacrificing accuracy, while the discrete-diffusion method leads to significant speed-ups at high optical depth. Our results suggest that a combination of spectral, velocity-dependent, Implicit Monte Carlo and discrete-diffusion Monte Carlo methods represents a robust approach for use in neutrino transport calculations in core-collapse supernovae. Our velocity-dependent scheme can easily be adapted to photon transport.
Abdikamalov, Ernazar; Ott, Christian D.; O'Connor, Evan [TAPIR, California Institute of Technology, MC 350-17, 1200 E California Blvd., Pasadena, CA 91125 (United States); Burrows, Adam; Dolence, Joshua C. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States); Loeffler, Frank; Schnetter, Erik, E-mail: firstname.lastname@example.com [Center for Computation and Technology, Louisiana State University, 216 Johnston Hall, Baton Rouge, LA 70803 (United States)
A new class of accelerated kinetic Monte Carlo algorithms
Kinetic (aka dynamic) Monte Carlo (KMC) is a powerful method for numerical simulations of time dependent evolution applied in a wide range of contexts including biology, chemistry, physics, nuclear sciences, financial engineering, etc. Generally, in a KMC the time evolution takes place one event at a time, where the sequence of events and the time intervals between them are selected (or sampled) using random numbers. While details of the method implementation vary depending on the model and context, there exist certain common issues that limit KMC applicability in almost all applications. Among such is the notorious 'flicker problem' where the same states of the systems are repeatedly visited but otherwise no essential evolution is observed. In its simplest form the flicker problem arises when two states are connected to each other by transitions whose rates far exceed the rates of all other transitions out of the same two states. In such cases, the model will endlessly hop between the two states otherwise producing no meaningful evolution. In most situation of practical interest, the trapping cluster includes more than two states making the flicker somewhat more difficult to detect and to deal with. Several methods have been proposed to overcome or mitigate the flicker problem, exactly [1-3] or approximately [4,5]. Of the exact methods, the one proposed by Novotny [1] is perhaps most relevant to our research. Novotny formulates the problem of escaping from a trapping cluster as a Markov system with absorbing states. Given an initial state inside the cluster, it is in principle possible to solve the Master Equation for the time dependent probabilities to find the walker in a given state (transient or absorbing) of the cluster at any time in the future. Novotny then proceeds to demonstrate implementation of his general method to trapping clusters containing the initial state plus one or two transient states and all of their absorbing states. Similar methods have been subsequently proposed in [refs] but applied in a different context. The most serious deficiency of the earlier methods is that size of the trapping cluster size is fixed and often too small to bring substantial simulation speedup. Furthermore, the overhead associated with solving for the probability distribution on the trapping cluster sometimes makes such simulations less efficient than the standard KMC. Here we report on a general and exact accelerated kinetic Monte Carlo algorithm generally applicable to arbitrary Markov models1. Two different implementations are attempted both based on incremental expansion of trapping sub-set of Markov states: (1) numerical solution of the Master Equation with absorbing states and (2) incremental graph reduction followed by randomization. Of the two implementations, the 2nd one performs better allowing, for the first time, to overcome trapping basins spanning several million Markov states. The new method is used for simulations of anomalous diffusion on a 2D substrate and of the kinetics of diffusive 1st order phase transformations in binary alloys. Depending on temperature and (alloy) super-saturation conditions, speedups of 3 to 7 orders of magnitude are demonstrated, with no compromise of simulation accuracy.
Bulatov, V V; Oppelstrup, T; Athenes, M
HYSPEC is a direct geometry spectrometer to be installed at the SNS [1] on beamline 14B where it will view a cryogenic coupled hydrogen moderator, The ''hybrid'' design combines time-of-flight spectroscopy with focusing Bragg optics to provide a high monochromatic flux on small single crystal samples, with a very low background at an extended detector bank. The instrument is optimized for an incident energy range of 3-90meV. It will have a medium energy resolution (2-10%) and will provide a flux on sample of the order of 10{sup 6}-10{sup 7} neutrons/s-cm{sup 2}. The spectrometer will be located in a satellite building outside the SNS experimental hall at the end of a 35m curved supermirror guide. A straight-slotted Fermi chopper will be used to monochromate the neutron beam and to determine the burst width. The 15cm high, 4cm wide beam will be focused onto a 2cm by 2cm area at the sample position using Bragg reflection from one of two crystal arrays. For unpolarized neutron studies these will be Highly Oriented Pyrolitic graphite crystals while for polarized neutron studies these will be replaced with Heusler alloy crystals. These focusing crystal arrays will be placed in a drum shield similar to those used for triple axis spectrometers. Hyspec will have a movable detector bank housing 160 position sensitive detectors. This detector bank will pivot about the sample axis. It will have a radius of 4.5m, a horizontal range of 60{sup o}, and a vertical range of {+-} 7.5{sup o}. In order to reduce background at the detector bank both a curved guide and a T0 chopper will be used. A bank of 20 supermirror bender polarization analyzers [2] will be used to spatially separate the polarized neutrons in the scattered beam so that both scattered neutron spin states can be measured simultaneously. The results of Monte Carlo simulations performed to optimize the instrument design will be discussed.
Monte Carlo simulation of radiation heat transfer in arrays of fixed discrete surfaces using cell-to-cell photon transport
Radiation heat transfer in an array of fixed discrete surfaces is an important problem that is particularly difficult to analyze because of the nonhomogeneous and anisotropic optical properties involved. This article presents an efficient Monte Carlo method for evaluating radiation heat transfer in arrays of fixed discrete surfaces. This Monte Carlo model has been optimized to take advantage of the regular arrangement of surfaces often encountered in these arrays. Monte Carlo model predictions have been compared with analytical and experimental results.
Drost, M.K. (Pacific Northwest Lab., Richland, WA (United States)); Welty, J.R. (Oregon State Univ., Corvallis, OR (United States))
LA COLONISATION DE L'AMAZONIE FACE AU DEVELOPPEMENT DURABLE : L'EXEMPLE DU BARRAGE DE BELO MONTE projets phare du programme Avança Brasil, le barrage de Belo Monte, barrage que nous replaçons dans l on the detailed study of one of the most important projcet of the Avança Brazil Program, the Belo Monte dam, we
Paris-Sud XI, Université de
Use of the linear variate method of Monte Carlo for estimating uncertainty in thermal-hydraulic codes
Thermal-hydraulic computer codes represent non-linear functions that may contain discontinuities. Monte Carlo methods are an effective means of accurately evaluating the effect of uncertainty on a nonlinear function with discontinuities, but the computational requirements of standard Monte Carlo methods may be prohibitive. The linear variate Monte Carlo method is a means of reducing the computational requirements. The linear variate method combines the linear response surface method with Monte Carlo analysis to obtain an efficient and accurate method of nonlinear uncertainty analysis. The method is applied to the power limit analysis for the Savannah River Site reactors. 7 refs., 2 figs., 3 tabs.
Kubic, W.L. Jr.; White, A.M. (Los Alamos National Lab., NM (USA); Westinghouse Savannah River Co., Aiken, SC (USA))
Vista, California: Energy Resources | Open Energy Information
2000368°, -117.2425355° 2000368°, -117.2425355° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":33.2000368,"lon":-117.2425355,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Microsoft Windows Vista Kernel Mode Security Support ...
... Corporation on the issues discussed as ... 24 6 OPERATIONAL ENVIRONMENT ..... ... key is EOR'ed with ...
Old Europe -New Vistas! Slovenia and Croatia
--ton mile charges, either uniform or segment-specific; a transportation waybill surcharge of, say, one. In the end, there was a waterway fuel tax enacted, starting in 1980 at four cents a gallon ranging up to 10 inland operators that the inland waterways fuel tax might be repealed because of the impact on the users
Reich, Peter B.
VISTA : a visualization tool for computer architects
As computer architectures continue to grow in complexity, software developers and hardware engineers cope with the increasing complexity by developing proprietary applications, simulations and tool sets to understand the ...
Mihalik, Aaron D. (Aaron Daniel), 1980-
Vista International Inc | Open Energy Information
Sector Efficiency, Wind energy Product Technology holding company, developing products in waste-to-energy gasification, low speed wind generators, alternative fuels, and...
VISTA - computational tools for comparative genomics
tools for comparative genomics Kelly A. Frazer 1 , LiorBerkeley, CA, 94720 Genomics Division, Lawrence Berkeleymultiple comparative genomics tools and provides users with
Frazer, Kelly A.; Pachter, Lior; Poliakov, Alexander; Rubin, Edward M.; Dubchak, Inna
CHUIA VISTA Development Services Department Building Division
generation plant including analyzing each Solar energy technology analysis and identifying source of project dissemination of policy through campaigns and mass media Kaomai Lanna Resort (family boutique hotel with 36/2008-12/2008 Championed environmental green direction: resort waste management procedure , energy saving facilities
Arroyo Vista Housing "Sustaining Our Future"
in bathrooms, common areas to shut off lighting when not occupied. Reduce hazardous materials o Specify TCLP
Rose, Michael R.
florescent fixtures with compact fluorescent fixtures. o Replace fluorescent exit signs with LED or Glow when not occupied. · Reduce hazardous materials o Specify TCLP-compliant (Toxicity Characteristic
George, Steven C.
Tests of Monte Carlo Independent Column Approximation With a Mixed-Layer Ocean Model
Tests of Monte Carlo Independent Column Tests of Monte Carlo Independent Column Approximation With a Mixed-Layer Ocean Model Petri Simo Järvenoja Heikki Järvinen Räisänen Finnish Meteorological Institute Figure 1. Root-mean-square sampling errors in local instant- aneous total (LW+SW) net flux at the surface and total radiative heating rate for the 1COL, CLDS, and REF approaches. Global rms values are given at the upper right hand corner of the plots. 1. Introduction The Monte Carlo Independent Column Approximation (McICA) separates the description of unresolved cloud structure from the radiative transfer solver very flexible ! unbiased with respect to ICA ! However, the radiative fluxes and heating rates contain conditional random errors ("McICA noise"). ? The topic of this poster: All previous tests of McICA
Tests of Monte Carlo Independent Column Approximation in the ECHAM5
Tests of Monte Carlo Independent Column Approximation in the ECHAM5 Tests of Monte Carlo Independent Column Approximation in the ECHAM5 Atmospheric GCM Raisanen, Petri Finnish Meteoroligical Institute Jarvenoja, Simo Finnish Meteorological Institute Jarvinen, Heikki Finnish Meteorological Institute Category: Modeling The Monte Carlo Independent Column Approximation (McICA) was recently introduced as a new approach for parametrizing broadband radiative fluxes in global climate models (GCMs). The McICA allows a flexible description of unresolved cloud structure, and it is unbiased with respect to the full ICA, but its results contain conditional random errors (i.e., noise). In this work, McICA and a stochastic cloud generator have been implemented to the Max Planck Institute for Meteorology's ECHAM5 atmospheric GCM. The
Revised methods for few-group cross sections generation in the Serpent Monte Carlo code
This paper presents new calculation methods, recently implemented in the Serpent Monte Carlo code, and related to the production of homogenized few-group constants for deterministic 3D core analysis. The new methods fall under three topics: 1) Improved treatment of neutron-multiplying scattering reactions, 2) Group constant generation in reflectors and other non-fissile regions and 3) Homogenization in leakage-corrected criticality spectrum. The methodology is demonstrated by a numerical example, comparing a deterministic nodal diffusion calculation using Serpent-generated cross sections to a reference full-core Monte Carlo simulation. It is concluded that the new methodology improves the results of the deterministic calculation, and paves the way for Monte Carlo based group constant generation. (authors)
Fridman, E. [Reactor Safety Div., Helmholz-Zentrum Dresden-Rossendorf, POB 51 01 19, Dresden, 01314 (Germany); Leppaenen, J. [VTT Technical Research Centre of Finland, POB 1000, FI-02044 VTT (Finland)
Crossing the mesoscale no-mans land via parallel kinetic Monte Carlo.
The kinetic Monte Carlo method and its variants are powerful tools for modeling materials at the mesoscale, meaning at length and time scales in between the atomic and continuum. We have completed a 3 year LDRD project with the goal of developing a parallel kinetic Monte Carlo capability and applying it to materials modeling problems of interest to Sandia. In this report we give an overview of the methods and algorithms developed, and describe our new open-source code called SPPARKS, for Stochastic Parallel PARticle Kinetic Simulator. We also highlight the development of several Monte Carlo models in SPPARKS for specific materials modeling applications, including grain growth, bubble formation, diffusion in nanoporous materials, defect formation in erbium hydrides, and surface growth and evolution.
Garcia Cardona, Cristina (San Diego State University); Webb, Edmund Blackburn, III; Wagner, Gregory John; Tikare, Veena; Holm, Elizabeth Ann; Plimpton, Steven James; Thompson, Aidan Patrick; Slepoy, Alexander (U. S. Department of Energy, NNSA); Zhou, Xiao Wang; Battaile, Corbett Chandler; Chandross, Michael Evan
Calculation of radiation therapy dose using all particle Monte Carlo transport
The actual radiation dose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimate dose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media.
Chandler, William P. (Tracy, CA); Hartmann-Siantar, Christine L. (San Ramon, CA); Rathkopf, James A. (Livermore, CA)
General purpose dynamic Monte Carlo with continuous energy for transient analysis
For safety assessments transient analysis is an important tool. It can predict maximum temperatures during regular reactor operation or during an accident scenario. Despite the fact that this kind of analysis is very important, the state of the art still uses rather crude methods, like diffusion theory and point-kinetics. For reference calculations it is preferable to use the Monte Carlo method. In this paper the dynamic Monte Carlo method is implemented in the general purpose Monte Carlo code Tripoli4. Also, the method is extended for use with continuous energy. The first results of Dynamic Tripoli demonstrate that this kind of calculation is indeed accurate and the results are achieved in a reasonable amount of time. With the method implemented in Tripoli it is now possible to do an exact transient calculation in arbitrary geometry. (authors)
Sjenitzer, B. L.; Hoogenboom, J. E. [Delft Univ. of Technology, Dept. of Radiation, Radionuclide and Reactors, Mekelweg 15, 2629JB Delft (Netherlands)
FREYA-a new Monte Carlo code for improved modeling of fission chains
A new simulation capability for modeling of individual fission events and chains and the transport of fission products in materials is presented. FREYA ( Fission Yield Event Yield Algorithm ) is a Monte Carlo code for generating fission events providing correlated kinematic information for prompt neutrons, gammas, and fragments. As a standalone code, FREYA calculates quantities such as multiplicity-energy, angular, and gamma-neutron energy sharing correlations. To study materials with multiplication, shielding effects, and detectors, we have integrated FREYA into the general purpose Monte Carlo code MCNP. This new tool will allow more accurate modeling of detector responses including correlations and the development of SNM detectors with increased sensitivity.
Hagmann, C A; Randrup, J; Vogt, R L
Monte Carlo simulation of the Massachusetts Institute of Technology Research Reactor
The three-dimensional continuous-energy MCNP Monte Carlo code is used to develop a versatile and accurate reactor physics model of the Massachusetts Institute of Technology Research Reactor 2 (MITR-2). The validation of the model against existing experimental data is presented. Core multiplication factors as well as fast neutron in-core flux measurements were used in the validation process. The agreement between the MCNP predictions and the experimentally determined values is very good, which indicates that the Monte Carlo model is correctly simulating the MITR-2.
Redmond, E.L. II; Yanch, J.C.; Harling, O.K. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Nuclear Engineering Dept.)
Penalized Splines for Smooth Representation of High-dimensional Monte Carlo Datasets
Detector response to a high-energy physics process is often estimated by Monte Carlo simulation. For purposes of data analysis, the results of this simulation are typically stored in large multi-dimensional histograms, which can quickly become both too large to easily store and manipulate and numerically problematic due to unfilled bins or interpolation artifacts. We describe here an application of the penalized spline technique to efficiently compute B-spline representations of such tables and discuss aspects of the resulting B-spline fits that simplify many common tasks in handling tabulated Monte Carlo data in high-energy physics analysis, in particular their use in maximum-likelihood fitting.
Whitehorn, Nathan; Lafebre, Sven
Calculating kinetics parameters and reactivity changes with continuous-energy Monte Carlo
The iterated fission probability interpretation of the adjoint flux forms the basis for a method to perform adjoint weighting of tally scores in continuous-energy Monte Carlo k-eigenvalue calculations. Applying this approach, adjoint-weighted tallies are developed for two applications: calculating point reactor kinetics parameters and estimating changes in reactivity from perturbations. Calculations are performed in the widely-used production code, MCNP, and the results of both applications are compared with discrete ordinates calculations, experimental measurements, and other Monte Carlo calculations.
Kiedrowski, Brian C [Los Alamos National Laboratory; Brown, Forrest B [Los Alamos National Laboratory; Wilson, Paul [UNIV. WISCONSIN
Pseudo-random number generators for Monte Carlo simulations on Graphics Processing Units
Basic uniform pseudo-random number generators are implemented on ATI Graphics Processing Units (GPU). The performance results of the realized generators (multiplicative linear congruential (GGL), XOR-shift (XOR128), RANECU, RANMAR, RANLUX and Mersenne Twister (MT19937)) on CPU and GPU are discussed. The obtained speed-up factor is hundreds of times in comparison with CPU. RANLUX generator is found to be the most appropriate for using on GPU in Monte Carlo simulations. The brief review of the pseudo-random number generators used in modern software packages for Monte Carlo simulations in high-energy physics is present.
Vadim Demchik
Modeling of Asymmetry between Gasoline and Crude Oil Prices: A Monte Carlo Comparison
An Engle---Granger two-step procedure is commonly used to estimate cointegrating vectors and consequently asymmetric error-correction models. This study uses Monte Carlo methods and demonstrates that the Engle---Granger two-step method leads to biased ... Keywords: Asymmetry, Gasoline, Modeling, Oil prices
Afshin Honarvar
Benchmark calculation of no-core Monte Carlo shell model in light nuclei
The Monte Carlo shell model is firstly applied to the calculation of the no-core shell model in light nuclei. The results are compared with those of the full configuration interaction. The agreements between them are within a few % at most.
T. Abe; P. Maris; T. Otsuka; N. Shimizu; Y. Utsuno; J. P. Vary
Dose verification with Monte Carlo technique for prostate brachytherapy implants with {sup 125}I sources
The Monte Carlo technique has been implemented to generate the dose distributions in a model prostate patient, implanted with iodine-125 ({sup 125}I) brachytherapy sources. The results of these calculations are also compared with the dose distributions calculated by a commercially available treatment planning system. The comparison shows that with the source strength suggested by the Monte Carlo technique, the current clinical planning system is found to provide 100% coverage of the prostate with the prescription dose for the same implant pattern. However, the dose-volume histogram of this investigation shows that the VariSeedTM treatment planning system has a 29% and 136% larger dose coverage for the 150% and 200% isodose lines, respectively, than the Monte Carlo simulation. These differences are attributed to the oversimplification of the current planning system using the point source approximation, and also to the interseed effects from multisources that are neglected in the conventional planning systems. The results of this study provide evidence that supports the use of the Monte Carlo technique in treatment planning systems to provide accurate dose calculations in brachytherapy implants.
Zhang Hualin [Department of Radiation Medicine, University of Kentucky Medical Center, Lexington, KY (United States)]. E-mail: firstname.lastname@example.com; Baker, Curtis [Department of Radiation Medicine, University of Kentucky Medical Center, Lexington, KY (United States); McKinsey, Rachel [Department of Radiation Medicine, University of Kentucky Medical Center, Lexington, KY (United States); Meigooni, Ali [Department of Radiation Medicine, University of Kentucky Medical Center, Lexington, KY (United States)
A Monte Carlo model for seeded atomic flows in the transition regime
A simple model for the numerical determination of separation effects in seeded atomic gas flows is presented. The model is based on the known possibility to provide a statistically convergent estimate of the exact solution for a linear transport equation ... Keywords: Compressible flows, Monte Carlo simulation, Multi-component flows, Numerical methods, Rarefied flows
S. Longo; P. Diomede
Abe, T; Otsuka, T; Shimizu, N; Utsuno, Y; Vary, J P; 10.1063/1.3584062
Abe, T.; Shimizu, N. [Department of Physics, the University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Maris, P.; Vary, J. P. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Otsuka, T. [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); CNS, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); NSCL, Michigan State University, East Lansing, Michigan 48824 (United States); Utsuno, Y. [ASRC, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)
GPU-Based Monte-Carlo Volume Raycasting Christof Rezk Salama
- ducing convincing images, yet flexible enough for digital productions in practice. 1 Introduction Volume can be found in the book by Engel et al. [1]. The first solely GPU-based implementations of volumeGPU-Based Monte-Carlo Volume Raycasting Christof Rezk Salama Computer Graphics Group, University
Blanz, Volker
State space exploration using feedback constraint generation and Monte-Carlo sampling
The systematic exploration of the space of all the behaviours of a software system forms the basis of numerous approaches to verification. However, existing approaches face many challenges with scalability and precision. We propose a framework for validating ... Keywords: model-checking, monte-carlo, statistical sampling, verification
Sriram Sankaranarayanan; Richard M. Chang; Guofei Jiang; Franjo Ivan?i?
Generation reliability assessment in power markets using Monte Carlo simulation and soft computing
Deregulation policy has caused some changes in the concepts of power systems reliability assessment and enhancement. In the present research, generation reliability is considered, and a method for its assessment is proposed using intelligent systems. ... Keywords: Generation reliability, Intelligent systems, Monte Carlo simulation, Power pool market
H. Haroonabadi; M. -R. Haghifam
Evaluating Simulation Heuristics in Monte?Carlo Tree Search and its Application to a Production Scheduling
This paper reports simulation heuristics of Monte?Carlo Tree Search (MCTS) and shows an application example. MCTS introduced by Coulom is a best?first search where pseudorandom simulations guide the solution of problem. Recent improvements on MCTS have produced strong computer Go program
Shimpei Matsumoto; Kosuke Kato; Noriaki Hirosue; Hiroaki Ishii
Monte Carlo simulation of solar radiation in maize canopies and its visualization
The spatial distribution of solar radiation casts important influences on eco-physiological functions of plant canopies. A simulation model of the three-dimensional of direct and indirect solar radiation in real maize canopies is developed from measured ... Keywords: Monte Carlo algorithm, plant canopy, radiosity, ray tracing, three-dimensional distribution
Zhang Yuan; Lao Cai-lian; Lee Bao-Guo; Chen Yan; Guo Yan; Wang Xi-ping; Ma Yun-tao; Zhao Ming
Is the Standard Monte Carlo Power Iteration Approach the Wrong Approach? Part 2
The recent work 'Is the Standard Monte Carlo Power Iteration Approach the Wrong Approach?' speculated that the second eigenfunction could be built using essentially the same 'building brick' approach that obtained the first eigenfunction in LA-UR-12-21928. This note shows that the speculation was at least partially correct, but not complete.
Booth, Thomas E. [Los Alamos National Laboratory
A Monte Carlo Assessment of Uncertainties in Heavy Precipitation Frequency Variations
A Monte Carlo analysis was used to assess the effects of missing data and limited station density on the uncertainties in the temporal variations of U.S. heavy precipitation event frequencies observed for 1895�2004 using data from the U.S. ...
Kenneth E. Kunkel; Thomas R. Karl; David R. Easterling
Monte Carlo simulation-based algorithms for estimating the reliability of mobile agent-based systems
In this paper, we propose two algorithms for estimating the task route reliability of mobile agent-based systems (MABS), which are based on the conditions of the underlying computer network. In addition, we propose a third algorithm for generating a ... Keywords: Algorithms, Mobile agents, Monte Carlo simulation, Random walk, Reliability
Mosaab Daoud; Qusay H. Mahmoud
Monte Carlo Study of the Scattering Error of a Quartz Reflective Absorption Tube
A Monte Carlo model was used to study the scattering error of an absorption meter with a divergent light beam and a limited acceptance angle of the receiver. Reflections at both ends of the tube were taken into account. Calculations of the effect ...
Jacek Piskozub; Piotr J. Flatau; J. V. Ronald Zaneveld
Use of single scatter electron monte carlo transport for medical radiation sciences
The single scatter Monte Carlo code CREEP models precise microscopic interactions of electrons with matter to enhance physical understanding of radiation sciences. It is designed to simulate electrons in any medium, including materials important for biological studies. It simulates each interaction individually by sampling from a library which contains accurate information over a broad range of energies.
Svatos, Michelle M. (Oakland, CA)
Monte Carlo Estimation of Time Mismatch Effect in an OFDM EER Architecture
Monte Carlo Estimation of Time Mismatch Effect in an OFDM EER Architecture J-F.Bercher, A.Diet, C technique due to non-linearities of the power amplification operation. EER architecture can be used to solve-linearities in the radio- frequency transmitter. Linearization methods are necessary. EER (Envelope Elimination
Baudoin, Geneviève
A Mersenne Twister Hardware Implementation for the Monte Carlo Localization Algorithm
Mobile robot localization is the problem of estimating a robot position based on sensor data and a map of the environment. One of the most used methods to address this problem is based on the Monte Carlo Localization (MCL) algorithm, which is a sample ... Keywords: Embedded mobile robotics, FPGA, Mersenne twister, Particle filter
Vanderlei Bonato; Bruno F. Mazzotti; Marcio Merino Fernandes; Eduardo Marques
Acceleration of Monte Carlo Criticality Calculations Using Deterministic-Based Starting Sources
A new automatic approach that uses approximate deterministic solutions for providing the starting fission source for Monte Carlo eigenvalue calculations was evaluated in this analysis. By accelerating the Monte Carlo source convergence and decreasing the number of cycles that has to be skipped before the tallies estimation, this approach was found to increase the efficiency of the overall simulation, even with the inclusion of the extra computational time required by the deterministic calculation. This approach was also found to increase the reliability of the Monte Carlo criticality calculations of loosely coupled systems because the use of the better starting source reduces the likelihood of producing an undersampled k{sub eff} due to the inadequate source convergence. The efficiency improvement was demonstrated using two of the standard test problems devised by the OECD/NEA Expert Group on Source Convergence in Criticality-Safety Analysis to measure the source convergence in Monte Carlo criticality calculations. For a fixed uncertainty objective, this approach increased the efficiency of the overall simulation by factors between 1.2 and 3 depending on the difficulty of the source convergence in these problems. The reliability improvement was demonstrated in a modified version of the 'k{sub eff} of the world' problem that was specifically designed to demonstrate the limitations of the current Monte Carlo power iteration techniques. For this problem, the probability of obtaining a clearly undersampled k{sub eff} decreased from 5% with a uniform starting source to zero with a deterministic starting source when batch sizes with more than 15,000 neutron/cycle were used.
Ibrahim, A. [University of Wisconsin; Peplow, Douglas E. [ORNL; Wagner, John C [ORNL; Mosher, Scott W [ORNL; Evans, Thomas M [ORNL
In the OSTI Collections: Monte Carlo Methods | OSTI, US Dept of Energy,
Monte Carlo Methods Monte Carlo Methods "The first thoughts and attempts I made ... were suggested by a question which occurred to me in 1946 as I was convalescing from an illness and playing solitaires. The question was what are the chances that a Canfield solitaire laid out with 52 cards will come out successfully? After spending a lot of time trying to estimate them by pure combinatorial calculations, I wondered whether a more practical method than 'abstract thinking' might not be to lay it out say one hundred times and simply observe and count the number of successful plays. This was already possible to envisage with the beginning of the new era of fast computers, and I immediately thought of problems of neutron diffusion and other questions of mathematical physics,
Calculating alpha Eigenvalues in a Continuous-Energy Infinite Medium with Monte Carlo
The {alpha} eigenvalue has implications for time-dependent problems where the system is sub- or supercritical. We present methods and results from calculating the {alpha}-eigenvalue spectrum for a continuous-energy infinite medium with a simplified Monte Carlo transport code. We formulate the {alpha}-eigenvalue problem, detail the Monte Carlo code physics, and provide verification and results. We have a method for calculating the {alpha}-eigenvalue spectrum in a continuous-energy infinite-medium. The continuous-time Markov process described by the transition rate matrix provides a way of obtaining the {alpha}-eigenvalue spectrum and kinetic modes. These are useful for the approximation of the time dependence of the system.
Betzler, Benjamin R. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory
The energy injection and losses in the Monte Carlo simulations of a diffusive shock
Although diffusive shock acceleration (DSA) could be simulated by some well-established models, the assumption of the injection rate from the thermal particles to the superthermal population is still a contentious problem. But in the self-consistent Monte Carlo simulations, because of the prescribed scattering law instead of the assumption of the injected function, hence particle injection rate is intrinsically defined by the prescribed scattering law. We expect to examine the correlation of the energy injection with the prescribed multiple scattering angular distributions. According to the Rankine-Hugoniot conditions, the energy injection and the losses in the simulation system can directly decide the shock energy spectrum slope. By the simulations performed with multiple scattering law in the dynamical Monte Carlo model, the energy injection and energy loss functions are obtained. As results, the case applying anisotropic scattering law produce a small energy injection and large energy losses leading to a s...
Wang, Xin
Adaptive kinetic Monte Carlo simulation of methanol decomposition on Cu(100)
The adaptive kinetic Monte Carlo method was used to calculate the dynamics of methanol decomposition on Cu(100) at room temperature over a time scale of minutes. Mechanisms of reaction were found using min-mode following saddle point searches based upon forces and energies from density functional theory. Rates of reaction were calculated with harmonic transition state theory. The dynamics followed a pathway from CH3-OH, CH3-O, CH2-O, CH-O and finally C-O. Our calculations confirm that methanol decomposition starts with breaking the O-H bond followed by breaking C-H bonds in the dehydrogenated intermediates until CO is produced. The bridge site on the Cu(100) surface is the active site for scissoring chemical bonds. Reaction intermediates are mobile on the surface which allows them to find this active reaction site. This study illustrates how the adaptive kinetic Monte Carlo method can model the dynamics of surface chemistry from first principles.
Xu, Lijun; Mei, Donghai; Henkelman, Graeme A.
Using high performance computing and Monte Carlo simulation for pricing american options
High performance computing (HPC) is a very attractive and relatively new area of research, which gives promising results in many applications. In this paper HPC is used for pricing of American options. Although the American options are very significant in computational finance; their valuation is very challenging, especially when the Monte Carlo simulation techniques are used. For getting the most accurate price for these types of options we use Quasi Monte Carlo simulation, which gives the best convergence. Furthermore, this algorithm is implemented on both GPU and CPU. Additionally, the CUDA architecture is used for harnessing the power and the capability of the GPU for executing the algorithm in parallel which is later compared with the serial implementation on the CPU. In conclusion this paper gives the reasons and the advantages of applying HPC in computational finance.
Cvetanoska, Verche
Under-Prediction of Localized Tally Uncertainties in Monte Carlo Eigenvalue Calculations
Modeling and simulation using Monte Carlo methods is widely used in nuclear reactor criticality benchmarking applications. However, obtaining good statistics not only takes a large amount of computational time, but it has been shown that localized tally uncertainties may be under-predicted by a factor of five or more in select cases. The primary components of this under-prediction include poor sampling due to improper source convergence and cycle-to-cycle correlations in the fission source. Additional components relate to the flux shape and the size of the tally cells. These issues must be understood and dealt with in order to support the practical use of modern Monte Carlo software packages.
Mervin, Mervin Brenden [University of Tennessee, Knoxville (UTK); Mosher, Scott W [ORNL; Wagner, John C [ORNL; Maldonado, G. Ivan [University of Tennessee, Knoxville (UTK)
Empirical Analysis of Stochastic Volatility Model by Hybrid Monte Carlo Algorithm
The stochastic volatility model is one of volatility models which infer latent volatility of asset returns. The Bayesian inference of the stochastic volatility (SV) model is performed by the hybrid Monte Carlo (HMC) algorithm which is superior to other Markov Chain Monte Carlo methods in sampling volatility variables. We perform the HMC simulations of the SV model for two liquid stock returns traded on the Tokyo Stock Exchange and measure the volatilities of those stock returns. Then we calculate the accuracy of the volatility measurement using the realized volatility as a proxy of the true volatility and compare the SV model with the GARCH model which is one of other volatility models. Using the accuracy calculated with the realized volatility we find that empirically the SV model performs better than the GARCH model.
Takaishi, Tetsuya
Comments on the use of the Monte Carlo method for criticality calculations
As evidenced by recent papers given at Nuclear Criticality Safety Division meetings, the use of the Monte Carlo method has become a very popular computational tool. The ease of use has undoubtably been a primary reason for this popularity. This ease of use, however, may lead to a false sense of security when using the method. Guidance on the effective use of the method and some suggestions on how to avoid some of the pitfalls that can occur are presented. (TFD)
Whitesides, G.E.
Radiative equilibrium in Monte Carlo radiative transfer using frequency distribution adjustment
The Monte Carlo method is a powerful tool for performing radiative equilibrium calculations, even in complex geometries. The main drawback of the standard Monte Carlo radiative equilibrium methods is that they require iteration, which makes them numerically very demanding. Bjorkman & Wood recently proposed a frequency distribution adjustment scheme, which allows radiative equilibrium Monte Carlo calculations to be performed without iteration, by choosing the frequency of each re-emitted photon such that it corrects for the incorrect spectrum of the previously re-emitted photons. Although the method appears to yield correct results, we argue that its theoretical basis is not completely transparent, and that it is not completely clear whether this technique is an exact rigorous method, or whether it is just a good and convenient approximation. We critically study the general problem of how an already sampled distribution can be adjusted to a new distribution by adding data points sampled from an adjustment distribution. We show that this adjustment is not always possible, and that it depends on the shape of the original and desired distributions, as well as on the relative number of data points that can be added. Applying this theorem to radiative equilibrium Monte Carlo calculations, we provide a firm theoretical basis for the frequency distribution adjustment method of Bjorkman & Wood, and we demonstrate that this method provides the correct frequency distribution through the additional requirement of radiative equilibrium. We discuss the advantages and limitations of this approach, and show that it can easily be combined with the presence of additional heating sources and the concept of photon weighting. However, the method may fail if small dust grains are included... (abridged)
Maarten Baes; Dimitris Stamatellos; Jonathan I. Davies; Anthony P. Whitworth; Sabina Sabatini; Sarah Roberts; Suzanne M. Linder; Rhodri Evans
Validation of a Monte Carlo Based Depletion Methodology Using HFIR Post-Irradiation Measurements
Post-irradiation uranium isotopic atomic densities within the core of the High Flux Isotope Reactor (HFIR) were calculated and compared to uranium mass spectrographic data measured in the late 1960s and early 70s [1]. This study was performed in order to validate a Monte Carlo based depletion methodology for calculating the burn-up dependent nuclide inventory, specifically the post-irradiation uranium
Chandler, David [ORNL; Maldonado, G Ivan [ORNL; Primm, Trent [ORNL
Calculation of shielding door thicknesses for radiation therapy facilities using the ITS Monte Carlo program
Shielding calculations for door thicknesses for megavoltage radiotherapy facilities with mazes are generally straightforward. To simplify the calculations, the standard formalism adopts several approximations relating to the average beam path, scattering coefficients, and the mean energy of the spectrum of scattered radiation. To test the accuracy of these calculations, the Monte Carlo program, ITS, was applied to this problem by determining the dose and energy spectrum of the radiation at the door for 4- and 10-MV bremsstrahlung beams incident on a phantom at isocenter. This was performed for mazes, one termed 'standard' and the other a shorter maze where the primary beam is incident on the wall adjacent to the door. The peak of the photon-energy spectrum at the door was found to be the same for both types of maze, independent of primary beam energy, and also, in the case of the conventional maze, of the primary beam orientation. The spectrum was harder for the short maze and for 10 MV vs. 4 MV. The thickness of the lead door for a short maze configuration was 1.5 cm for 10 MV and 1.2 cm for 4 MV vs. approximately less than 1 mm for a conventional maze. For the conventional maze, the Monte Carlo calculation predicts the dose at the door to be lower than given by NCRP 49 and NCRP 51 by about a factor of 2 at 4 MV but to be the same at 10 MV. For the short maze, the Monte Carlo predicts the dose to be a factor of 3 lower for 4 MV and about a factor of 1.5 lower for 10 MV. Experimental results support the Monte Carlo findings for the short maze.
Biggs, P.J. (Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston (United States))
A comparison of the Monte Carlo and the flux gradient method for atmospheric diffusion
In order to model the dispersal of atmospheric pollutants in the planetary boundary layer, various methods of parameterizing turbulent diffusion have been employed. The purpose of this paper is to use a three-dimensional particle-in-cell transport and diffusion model to compare the Markov chain (Monte Carlo) method of statistical particle diffusion with the deterministic flux gradient (K-theory) method. The two methods are heavily used in the study of atmospheric diffusion under complex conditions, with the Monte Carlo method gaining in popularity partly because of its more direct application of turbulence parameters. The basis of comparison is a data set from night-time drainage flow tracer experiments performed by the US Department of Energy Atmospheric Studies in Complex Terrain (ASCOT) program at the Geysers geothermal region in northern California. The Atmospheric Diffusion Particle-In-Cell (ADPIC) model used is the main model in the Lawrence Livermore National Laboratory emergency response program: Atmospheric Release Advisory Capability (ARAC). As a particle model, it can simulate diffusion in both the flux gradient and Monte Carlo modes. 9 refs., 6 figs.
Lange, R.
Nonequilibrium candidate Monte Carlo: A new tool for efficient equilibrium simulation
Metropolis Monte Carlo simulation is a powerful tool for studying the equilibrium properties of matter. In complex condensed-phase systems, however, it is difficult to design Monte Carlo moves with high acceptance probabilities that also rapidly sample uncorrelated configurations. Here, we introduce a new class of moves based on nonequilibrium dynamics: candidate configurations are generated through a finite-time process in which a system is actively driven out of equilibrium, and accepted with criteria that preserve the equilibrium distribution. The acceptance rule is similar to the Metropolis acceptance probability, but related to the nonequilibrium work rather than the instantaneous energy difference. Our method is applicable to sampling from both a single thermodynamic state or a mixture of thermodynamic states, and allows both coordinates and thermodynamic parameters to be driven in nonequilibrium proposals. While generating finite-time switching trajectories incurs an additional cost, driving some degrees of freedom while allowing others to evolve naturally can lead to large enhancements in acceptance probabilities, greatly reducing structural correlation times. Using nonequilibrium driven processes vastly expands the repertoire of useful Monte Carlo proposals in simulations of dense solvated systems.
Nilmeier, Jerome P.; Crooks, Gavin E.; Minh, David D. L.; Chodera, John D.
Combining Total Monte Carlo and Benchmarks for nuclear data uncertainty propagation on an LFRs safety parameters
Analyses are carried out to assess the impact of nuclear data uncertainties on keff for the European Lead Cooled Training Reactor (ELECTRA) using the Total Monte Carlo method. A large number of Pu-239 random ENDF-formated libraries generated using the TALYS based system were processed into ACE format with NJOY99.336 code and used as input into the Serpent Monte Carlo neutron transport code to obtain distribution in keff. The keff distribution obtained was compared with the latest major nuclear data libraries - JEFF-3.1.2, ENDF/B-VII.1 and JENDL-4.0. A method is proposed for the selection of benchmarks for specific applications using the Total Monte Carlo approach. Finally, an accept/reject criterion was investigated based on chi square values obtained using the Pu-239 Jezebel criticality benchmark. It was observed that nuclear data uncertainties in keff were reduced considerably from 748 to 443 pcm by applying a more rigid acceptance criteria for accepting random files.
Alhassan, Erwin; Duan, Junfeng; Gustavsson, Cecilia; Koning, Arjan; Pomp, Stephan; Rochman, Dimitri; �sterlund, Michael
A second-quantized red herring in full configuration-interaction Monte Carlo
Full configuration-interaction quantum Monte Carlo (FCI-QMC) is a Monte Carlo method that allows for exact solution of the ground state of fermionic Hamiltonians (albeit at exponential cost). FCI-QMC involves stochastic projection to the ground state, working in a basis of second- quantized determinants. While a Fermi sign problem still exists within FCI-QMC, it has been suggested that even without annihilation the sign problem is fundamentally distinct from that of more standard techniques such as diffusion Monte Carlo, as a result of working in determinant space. Furthermore, it is widely believed that this distinction is at least partially responsible for the success of FCI-QMC in mitigating the sign problem. In this paper, we show that second quantization is a red herring; the sign problem of FCI-QMC comes from the conventional instability to a bosonic ground state, and in fact FCI-QMC without annihilation can be equated step-by-step to a first-quantized algorithm where anti-symmetry comes only from initi...
Kolodrubetz, Michael
Quantum Monte-Carlo method applied to Non-Markovian barrier transmission
In nuclear fusion and fission, fluctuation and dissipation arise due to the coupling of collective degrees of freedom with internal excitations. Close to the barrier, both quantum, statistical and non-Markovian effects are expected to be important. In this work, a new approach based on quantum Monte-Carlo addressing this problem is presented. The exact dynamics of a system coupled to an environment is replaced by a set of stochastic evolutions of the system density. The quantum Monte-Carlo method is applied to systems with quadratic potentials. In all range of temperature and coupling, the stochastic method matches the exact evolution showing that non-Markovian effects can be simulated accurately. A comparison with other theories like Nakajima-Zwanzig or Time-ConvolutionLess ones shows that only the latter can be competitive if the expansion in terms of coupling constant is made at least to fourth order. A systematic study of the inverted parabola case is made at different temperatures and coupling constants. The asymptotic passing probability is estimated in different approaches including the Markovian limit. Large differences with the exact result are seen in the latter case or when only second order in the coupling strength is considered as it is generally assumed in nuclear transport models. On opposite, if fourth order in the coupling or quantum Monte-Carlo method is used, a perfect agreement is obtained.
G. Hupin; D. Lacroix
Spatial homogenization of thermal feedback regions in Monte Carlo reactor calculations
An integrated thermal-hydraulic feedback module has previously been developed for the Monte Carlo transport solver, MC21. The module incorporates a flexible input format that allows the user to describe heat transfer and coolant flow paths within the geometric model at any level of spatial detail desired. The effect that the varying levels of spatial homogenization of thermal regions has on the accuracy of the Monte Carlo simulations is examined in this study. Six thermal feedback mappings are constructed from the same geometric model of the Calvert Cliffs core. The spatial homogenization of the thermal regions is varied, giving each scheme a different level of detail, and the adequacy of the spatial homogenization is determined based on the eigenvalue produced by each Monte Carlo calculation. The purpose of these numerical experiments is to determine the level of detail necessarily to accurately capture the thermal feedback effect on reactivity. Several different core models are considered: axial-flow only, axial and lateral flow, asymmetry due to control rod insertion, and fuel heating (temperature -dependent cross sections). The thermal results generated by the MC21 thermal feedback module are consistent with expectations. Based upon the numerical experiments conducted it is concluded that the amount of spatial detail necessary to accurately capture the feedback effect on reactivity is relatively small. Homogenization at the assembly level for the Calvert Cliffs PWR model results in a similar power defect to that calculated with individual pin-cells modeled as explicit thermal regions. (authors)
Hanna, B. R.; Gill, D. F.; Griesheimer, D. P. [Bertis Atomic Power Laboratory, Bechtel Marine Propulsion Corporation, P.O. Box 79, West Mifflin, PA 15122 (United States)
The generalized hybrid Monte Carlo (GHMC) method combines Metropolis corrected constant energy simulations with a partial random refreshment step in the particle momenta. The standard detailed balance condition requires that momenta are negated upon rejection of a molecular dynamics proposal step. The implication is a trajectory reversal upon rejection, which is undesirable when interpreting GHMC as thermostated molecular dynamics. We show that a modified detailed balance condition can be used to implement GHMC without momentum flips. The same modification can be applied to the generalized shadow hybrid Monte Carlo (GSHMC) method. Numerical results indicate that GHMC/GSHMC implementations with momentum flip display a favorable behavior in terms of sampling efficiency, i.e., the traditional GHMC/GSHMC implementations with momentum flip got the advantage of a higher acceptance rate and faster decorrelation of Monte Carlo samples. The difference is more pronounced for GHMC. We also numerically investigate the behavior of the GHMC method as a Langevin-type thermostat. We find that the GHMC method without momentum flip interferes less with the underlying stochastic molecular dynamics in terms of autocorrelation functions and it to be preferred over the GHMC method with momentum flip. The same finding applies to GSHMC.
Akhmatskaya, Elena [Fujitsu Laboratories of Europe Ltd (FLE), Hayes Park Central, Hayes End Road, Hayes UB4 8FE (United Kingdom); Bou-Rabee, Nawaf [Department of Mathematics, Freie Universitaet Berlin, Arnimallee 2-6, 14195 Berlin (Germany); Reich, Sebastian [Universitaet Potsdam, Institut fuer Mathematik, Am Neuen Palais 10, D-14469 Potsdam (Germany)], E-mail: email@example.com
MC21 analysis of the nuclear energy agency Monte Carlo performance benchmark problem
Due to the steadily decreasing cost and wider availability of large scale computing platforms, there is growing interest in the prospects for the use of Monte Carlo for reactor design calculations that are currently performed using few-group diffusion theory or other low-order methods. To facilitate the monitoring of the progress being made toward the goal of practical full-core reactor design calculations using Monte Carlo, a performance benchmark has been developed and made available through the Nuclear Energy Agency. A first analysis of this benchmark using the MC21 Monte Carlo code was reported on in 2010, and several practical difficulties were highlighted. In this paper, a newer version of MC21 that addresses some of these difficulties has been applied to the benchmark. In particular, the confidence-interval-determination method has been improved to eliminate source correlation bias, and a fission-source-weighting method has been implemented to provide a more uniform distribution of statistical uncertainties. In addition, the Forward-Weighted, Consistent-Adjoint-Driven Importance Sampling methodology has been applied to the benchmark problem. Results of several analyses using these methods are presented, as well as results from a very large calculation with statistical uncertainties that approach what is needed for design applications. (authors)
Kelly, D. J.; Sutton, T. M. [Knolls Atomic Power Laboratory, Bechtel Marine Propulsion Corporation, P. O. Box 1072, Schenectady, NY 12301-1072 (United States); Wilson, S. C. [Bertis Atomic Power Laboratory, Bechtel Marine Propulsion Corporation, P. O. Box 79, West Mifflin, PA 15122-0079 (United States)
Erwin Alhassan; Henrik Sj�strand; Junfeng Duan; Cecilia Gustavsson; Arjan Koning; Stephan Pomp; Dimitri Rochman; Michael �sterlund
Monte Carlo Simulation of Daily Regional Sulfur Distribution: Comparison with SURE Sulfate Data and Visual Range Observations during August 1977
The daily distribution of sulfate concentration over the eastern United States during August 1977 is simulated by a Monte Carlo model using quantized emissions, positioned in accordance with the 1973 EPA SO2 emission inventory. Horizontal ...
D. E. Patterson; R. B. Husar; W. E. Wilson; L. F. Smith
Dispersion of Particles Released into a Neutral Planetary Boundary Layer Using a Markov Chain�Monte Carlo Model
The dispersion and concentration of particles (fluid elements) that are continuously released into a neutral planetary boundary layer is presented. The velocity fluctuations of the particles are generated using a Markov chain�Monte Carlo (MCMC) ...
R. Avila; S. S. Raza
Computational Cost and Accuracy in Calculating Three-Dimensional Radiative Transfer: Results for New Implementations of Monte Carlo and SHDOM
This paper examines the tradeoffs between computational cost and accuracy for two new state-of-the-art codes for computing three-dimensional radiative transfer: a community Monte Carlo model and a parallel implementation of the Spherical ...
Robert Pincus; K. Franklin Evans
Bayesian Inference and Markov Chain Monte Carlo Sampling to Reconstruct a Contaminant Source on a Continental Scale
A methodology combining Bayesian inference with Markov chain Monte Carlo (MCMC) sampling is applied to a real accidental radioactive release that occurred on a continental scale at the end of May 1998 near Algeciras, Spain. The source parameters (...
Luca Delle Monache; Julie K. Lundquist; Branko Kosovi?; Gardar Johannesson; Kathleen M. Dyer; Roger D. Aines; Fotini K. Chow; Rich D. Belles; William G. Hanley; Shawn C. Larsen; Gwen A. Loosmore; John J. Nitao; Gayle A. Sugiyama; Philip J. Vogt
Tips for Parents & Families of Arroyo Vista Residents Parent's Guide to Arroyo Vista
400 Maryland Ave. S.W. Washington, DC 20202-5920 202-260-3887 For routine questions about FERPA hours are 8:00 AM to 1:00 PM, and 2:00 PM to 5:00 PM, PST. · Cashiering Windows are open from 8:30 AM
Stanford, Kyle
TOPAS: An innovative proton Monte Carlo platform for research and clinical applications
Purpose: While Monte Carlo particle transport has proven useful in many areas (treatment head design, dose calculation, shielding design, and imaging studies) and has been particularly important for proton therapy (due to the conformal dose distributions and a finite beam range in the patient), the available general purpose Monte Carlo codes in proton therapy have been overly complex for most clinical medical physicists. The learning process has large costs not only in time but also in reliability. To address this issue, we developed an innovative proton Monte Carlo platform and tested the tool in a variety of proton therapy applications. Methods: Our approach was to take one of the already-established general purpose Monte Carlo codes and wrap and extend it to create a specialized user-friendly tool for proton therapy. The resulting tool, TOol for PArticle Simulation (TOPAS), should make Monte Carlo simulation more readily available for research and clinical physicists. TOPAS can model a passive scattering or scanning beam treatment head, model a patient geometry based on computed tomography (CT) images, score dose, fluence, etc., save and restart a phase space, provides advanced graphics, and is fully four-dimensional (4D) to handle variations in beam delivery and patient geometry during treatment. A custom-designed TOPAS parameter control system was placed at the heart of the code to meet requirements for ease of use, reliability, and repeatability without sacrificing flexibility. Results: We built and tested the TOPAS code. We have shown that the TOPAS parameter system provides easy yet flexible control over all key simulation areas such as geometry setup, particle source setup, scoring setup, etc. Through design consistency, we have insured that user experience gained in configuring one component, scorer or filter applies equally well to configuring any other component, scorer or filter. We have incorporated key lessons from safety management, proactively removing possible sources of user error such as line-ordering mistakes. We have modeled proton therapy treatment examples including the UCSF eye treatment head, the MGH stereotactic alignment in radiosurgery treatment head and the MGH gantry treatment heads in passive scattering and scanning modes, and we have demonstrated dose calculation based on patient-specific CT data. Initial validation results show agreement with measured data and demonstrate the capabilities of TOPAS in simulating beam delivery in 3D and 4D. Conclusions: We have demonstrated TOPAS accuracy and usability in a variety of proton therapy setups. As we are preparing to make this tool freely available for researchers in medical physics, we anticipate widespread use of this tool in the growing proton therapy community.
Perl, J.; Shin, J.; Schuemann, J.; Faddegon, B.; Paganetti, H. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); University of California San Francisco Comprehensive Cancer Center, 1600 Divisadero Street, San Francisco, California 94143-1708 (United States); Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); University of California San Francisco Comprehensive Cancer Center, 1600 Divisadero Street, San Francisco, California 94143-1708 (United States); Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States)
A dose point kernel database using GATE Monte Carlo simulation toolkit for nuclear medicine applications: Comparison with other Monte Carlo codes
Purpose: GATE is a Monte Carlo simulation toolkit based on the Geant4 package, widely used for many medical physics applications, including SPECT and PET image simulation and more recently CT image simulation and patient dosimetry. The purpose of the current study was to calculate dose point kernels (DPKs) using GATE, compare them against reference data, and finally produce a complete dataset of the total DPKs for the most commonly used radionuclides in nuclear medicine. Methods: Patient-specific absorbed dose calculations can be carried out using Monte Carlo simulations. The latest version of GATE extends its applications to Radiotherapy and Dosimetry. Comparison of the proposed method for the generation of DPKs was performed for (a) monoenergetic electron sources, with energies ranging from 10 keV to 10 MeV, (b) beta emitting isotopes, e.g., {sup 177}Lu, {sup 90}Y, and {sup 32}P, and (c) gamma emitting isotopes, e.g., {sup 111}In, {sup 131}I, {sup 125}I, and {sup 99m}Tc. Point isotropic sources were simulated at the center of a sphere phantom, and the absorbed dose was stored in concentric spherical shells around the source. Evaluation was performed with already published studies for different Monte Carlo codes namely MCNP, EGS, FLUKA, ETRAN, GEPTS, and PENELOPE. A complete dataset of total DPKs was generated for water (equivalent to soft tissue), bone, and lung. This dataset takes into account all the major components of radiation interactions for the selected isotopes, including the absorbed dose from emitted electrons, photons, and all secondary particles generated from the electromagnetic interactions. Results: GATE comparison provided reliable results in all cases (monoenergetic electrons, beta emitting isotopes, and photon emitting isotopes). The observed differences between GATE and other codes are less than 10% and comparable to the discrepancies observed among other packages. The produced DPKs are in very good agreement with the already published data, which allowed us to produce a unique DPKs dataset using GATE. The dataset contains the total DPKs for {sup 67}Ga, {sup 68}Ga, {sup 90}Y, {sup 99m}Tc, {sup 111}In, {sup 123}I, {sup 124}I, {sup 125}I, {sup 131}I, {sup 153}Sm, {sup 177}Lu {sup 186}Re, and {sup 188}Re generated in water, bone, and lung. Conclusions: In this study, the authors have checked GATE's reliability for absorbed dose calculation when transporting different kind of particles, which indicates its robustness for dosimetry applications. A novel dataset of DPKs is provided, which can be applied in patient-specific dosimetry using analytical point kernel convolution algorithms.
Papadimitroulas, Panagiotis; Loudos, George; Nikiforidis, George C.; Kagadis, George C. [Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 265 04 (Greece) and Department of Medical Instruments Technology, Technological Educational institute of Athens, Ag. Spyridonos Street, Egaleo GR 122 10, Athens (Greece); Department of Medical Instruments Technology, Technological Educational institute of Athens, Ag. Spyridonos Street, Egaleo GR 122 10, Athens (Greece); Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 265 04 (Greece)
RBU is a digital computer program for the detailed calculation of the neutron, reactivity, and isotopic history of a reactor in which relatively exact models of the geometry and physical processes are included to permit reliable pre dictions of fuel costs and reactor performance. The program uses the Monte Carlo method to obtain the fine structure of the neutron flux in three space dimensions and energy. Using this fine structure, cross sections are averaged over space and energy to obtain the neutronic properties for equivalent homogeneous one- dimensional regions of space and ranges of energy. These are used in diffusion calculations to obtain the macroscopic flux distribution throughout the reactor. The consumption and production of isotopes is computed for a time step by the solution of sets of partial differential equations involving both the macroscopic and microscopic fluxes. With the new concentrations, diffusion calculations are performed again to obtain macroscopic fluxes for the next time step. At variable intervals, Monte Carlo calculations are again performed to determine the changes in microscopic flux distributions. The cycle is repeated until conditions on the reactivity or other properties dictate the end of the calculation. Programmed control rod manipulation may be included in the calculation. The Monte Carlo, diffusion, or burnup portions of the program may be used separately. The unresolved resonance range is treated by random selection of resonance parameters from appropriate distributions using the Doppler broadened single level Breit- Wigner formula. Resolved resonances are treated similarly with the exception that specific values of the resonance parameters are used. The effects of molecular binding and thermal motion of the nuclei on near-thermal scattering are treated by a simple model capable of incorporating the pertinent physical theory and data. (auth)
Leshan, E.J.; Burr, J.R.; Temme, M.; Thompson, G.T.; Triplett, J.R.
A User's Manual for MASH V1.5 - A Monte Carlo Adjoint Shielding Code System
The Monte Carlo ~djoint ~ielding Code System, MASH, calculates neutron and gamma- ray environments and radiation protection factors for armored military vehicles, structures, trenches, and other shielding configurations by coupling a forward discrete ordinates air- over-ground transport calculation with an adjoint Monte Carlo treatment of the shielding geometry. Efficiency and optimum use of computer time are emphasized. The code system includes the GRTUNCL and DORT codes for air-over-ground transport calculations, the MORSE code with the GIFT5 combinatorial geometry package for adjoint shielding calculations, and several peripheral codes that perform the required data preparations, transformations, and coupling functions. The current version, MASH v 1.5, is the successor to the original MASH v 1.0 code system initially developed at Oak Ridge National Laboratory (ORNL). The discrete ordinates calculation determines the fluence on a coupling surface surrounding the shielding geometry due to an external neutron/gamma-ray source. The Monte Carlo calculation determines the effectiveness of the fluence at that surface in causing a response in a detector within the shielding geometry, i.e., the "dose importance" of the coupling surface fluence. A coupling code folds the fluence together with the dose importance, giving the desired dose response. The coupling code can determine the dose response as a function of the shielding geometry orientation relative to the source, distance from the source, and energy response of the detector. This user's manual includes a short description of each code, the input required to execute the code along with some helpful input data notes, and a representative sample problem.
C. O. Slater; J. M. Barnes; J. O. Johnson; J.D. Drischler
Sequential Monte Carlo simulation for composite power system reliability analysis with time varying loads
The paper illustrates the development and utilization of an annual chronological load curve for each load bus in a composite generation and transmission system and a sequential Monte Carlo simulation approach for composite system reliability assessment. Antithetic variates as a variance reduction technique has been applied to the simulation model to increase the efficiency of the simulation. An approximate method using a load duration curve of the system load and an enumeration process have been applied to the developed load model and the results are compared in this paper.
Sankarakrishnan, A.; Billinton, R. [Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada). Power Systems Research Group
First Results From GLAST-LAT Integrated Towers Cosmic Ray Data Taking And Monte Carlo Comparison
GLAST Large Area Telescope (LAT) is a gamma ray telescope instrumented with silicon-strip detector planes and sheets of converter, followed by a calorimeter (CAL) and surrounded by an anticoincidence system (ACD). This instrument is sensitive to gamma rays in the energy range between 20 MeV and 300 GeV. At present, the first towers have been integrated and pre-launch data taking with cosmic ray muons is being performed. The results from the data analysis carried out during LAT integration will be discussed and a comparison with the predictions from the Monte Carlo simulation will be shown.
Brigida, M.; Caliandro, A.; Favuzzi, C.; Fusco, P.; Gargano, F.; Giordano, F.; Giglietto, N.; Loparco, F.; Marangelli, B.; Mazziotta, M.N.; Mirizzi, N.; Raino, S.; Spinelli, P.; /Bari U. /INFN, Bari
A Hybrid (Monte-Carlo/Deterministic) Approach for Multi-Dimensional Radiation Transport
A novel hybrid Monte Carlo transport scheme is demonstrated in a scene with solar illumination, scattering and absorbing 2D atmosphere, a textured reflecting mountain, and a small detector located in the sky (mounted on a satellite or a airplane). It uses a deterministic approximation of an adjoint transport solution to reduce variance, computed quickly by ignoring atmospheric interactions. This allows significant variance and computational cost reductions when the atmospheric scattering and absorption coefficient are small. When combined with an atmospheric photon-redirection scheme, significant variance reduction (equivalently acceleration) is achieved in the presence of atmospheric interactions.
Guillaume Bal; Anthony Davis; Ian Langmore
Extrapolation method in the Monte Carlo Shell Model and its applications
We demonstrate how the energy-variance extrapolation method works using the sequence of the approximated wave functions obtained by the Monte Carlo Shell Model (MCSM), taking {sup 56}Ni with pf-shell as an example. The extrapolation method is shown to work well even in the case that the MCSM shows slow convergence, such as {sup 72}Ge with f5pg9-shell. The structure of {sup 72}Se is also studied including the discussion of the shape-coexistence phenomenon.
Shimizu, Noritaka; Abe, Takashi [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Utsuno, Yutaka [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Mizusaki, Takahiro [Institute of Natural Sciences, Senshu University, Tokyo, 101-8425 (Japan); Otsuka, Takaharu [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan (United States); Honma, Michio [Center for Mathematical Sciences, Aizu University, Aizu-Wakamatsu, Fukushima 965-8580 (Japan)
Characterisation of radiation damage in silicon photomultipliers with a Monte Carlo model
Measured response functions and low photon yield spectra of silicon photomultipliers (SiPM) were compared to multi-photoelectron pulse-height distributions generated by a Monte Carlo model. Characteristic parameters for SiPM were derived. The devices were irradiated with 14 MeV electrons at the Mainz microtron MAMI. It is shown that the first noticeable damage consists of an increase in the rate of dark pulses and the loss of uniformity in the pixel gains. Higher radiation doses reduced also the photon detection efficiency. The results are especially relevant for applications of SiPM in fibre detectors at high luminosity experiments.
S. Sanchez Majos; P. Achenbach; J. Pochodzalla
Quest for precision in hadronic cross sections at low energy: Monte Carlo tools vs. experimental data
We present the achievements of the last years of the experimental and theoretical groups working on hadronic cross section measurements at the low energy e+e- colliders in Beijing, Frascati, Ithaca, Novosibirsk, Stanford and Tsukuba and on tau decays. We sketch the prospects in these fields for the years to come. We emphasise the status and the precision of the Monte Carlo generators used to analyse the hadronic cross section measurements obtained as well with energy scans as with radiative return, to determine luminosities and tau decays. The radiative corrections fully or approximately implemented in the various codes and the contribution of the vacuum polarisation are discussed.
Actis, S; Arbuzov, A; Balossini, G; Beltrame, P; Bignamini, C; Bonciani, R; Carloni Calame, C M; Cherepanov, V; Czakon, M; Czyz, H; Denig, A; Eidelman, S; Fedotovich, G V; Ferroglia, A; Gluza, J; Grzeli nska, A; Gunia, M; Hafner, A; Ignatov, F; Jadach, S; Jegerlehner, F; Kalinowski, A; Kluge, W; Korchin, A; Kuhn, J H; Kuraev, E A; Lukin, P; Mastrolia, P; Montagna, G; Muller, S E; Nguyen, F; Nicrosini, O; Nomura, D; Pakhlova, G; Pancheri, G; Passera, M; Penin, A; Piccinini, F; Placzek, W; Przedzinski, T; Remiddi, E; Riemann, T; Rodrigo, G; Roig, P; Shekhovtsova, O; Shen, C P; Sibidanov, A L; Teubner, T; Trentadue, L; Venanzoni, G; van der Bij, J J; Wang, P; Ward, B F L; Was, Z; Worek, M; Yuan, C Z
SIM-RIBRAS: A Monte-Carlo simulation package for RIBRAS system
SIM-RIBRAS is a Root-based Monte-Carlo simulation tool designed to help RIBRAS users on experience planning and experimental setup enhancing and caracterization. It is divided into two main programs: CineRIBRAS, aiming beam kinematics, and SolFocus, aiming beam optics. SIM-RIBRAS replaces other methods and programs used in the past, providing more complete and accurate results and requiring much less manual labour. Moreover, the user can easily make modifications in the codes, adequating it for specific requirements of an experiment.
Leistenschneider, E.; Lepine-Szily, A.; Lichtenthaeler, R. [Departamento de Fisica Nuclear, Instituto de Fisica, Universidade de Sao Paulo (Brazil)
ETRANMS: a one-dimensional Monte Carlo electron/photon transport code for multimaterial targets
ETRANMS is an LLL-modified version of the one-dimensional electron/ photon transport code ETRAN 15 developed at the National bureau of Standards. The major modifications include the use of LLL photon cross sections and the application to multislab, multimaterial targets. The code uses Monte Carlo sampling techniques to calculate electron and photon transport and energy and charge deposition within target material subjected to electron or photon radiation. It has been programmed to be a very rapid running, user-oriented code for use on LLL's CDC 7600 computers. (auth)
Kovar, F.R.
A 3D Monte Carlo Photoionization Code for Modeling Diffuse Ionized Gas
We have developed a three dimensional Monte Carlo photoionization code tailored for the study of Galactic H II regions and the percolation of ionizing photons in diffuse ionized gas. We describe the code, our calculation of photoionization, heating & cooling, and the approximations we have employed for the low density H II regions we wish to study. Our code gives results in agreement with the Lexington H II region benchmarks. We show an example of a 2D shadowed region and point out the very significant effect that diffuse radiation produced by recombinations of helium has on the temperature within the shadow.
Wood, K; Ercolano, B
Monte Carlo simulation of ferroelectric domain structure: Electrostatic and elastic strain energy contributions
A lattice-Monte Carlo approach was developed to simulate ferroelectric domain behavior. The model utilizes a Hamiltonian for the total energy that includes electrostatic terms (involving dipole-dipole interactions, local polarization gradients, and applied electric field), and elastic strain energy. The contributions of these energy components to the domain structure and to the overall applied field response of the system were examined. In general, the model exhibited domain structure characteristics consistent with those observed in a tetragonally distorted ferroelectric. Good qualitative agreement between the appearance of simulated electrical hysteresis loops and those characteristic of real ferroelectric materials was found.
west of New York City. ORU is a key participant in Con Edison's 272 million Smart Grid Investment Grant (SGIG) project to modernize electric distribution systems. With 136...
Use of SCALE Continuous-Energy Monte Carlo Tools for Eigenvalue Sensitivity Coefficient Calculations
The TSUNAMI code within the SCALE code system makes use of eigenvalue sensitivity coefficients for an extensive number of criticality safety applications, such as quantifying the data-induced uncertainty in the eigenvalue of critical systems, assessing the neutronic similarity between different critical systems, and guiding nuclear data adjustment studies. The need to model geometrically complex systems with improved fidelity and the desire to extend TSUNAMI analysis to advanced applications has motivated the development of a methodology for calculating sensitivity coefficients in continuous-energy (CE) Monte Carlo applications. The CLUTCH and Iterated Fission Probability (IFP) eigenvalue sensitivity methods were recently implemented in the CE KENO framework to generate the capability for TSUNAMI-3D to perform eigenvalue sensitivity calculations in continuous-energy applications. This work explores the improvements in accuracy that can be gained in eigenvalue and eigenvalue sensitivity calculations through the use of the SCALE CE KENO and CE TSUNAMI continuous-energy Monte Carlo tools as compared to multigroup tools. The CE KENO and CE TSUNAMI tools were used to analyze two difficult models of critical benchmarks, and produced eigenvalue and eigenvalue sensitivity coefficient results that showed a marked improvement in accuracy. The CLUTCH sensitivity method in particular excelled in terms of efficiency and computational memory requirements.
Perfetti, Christopher M [ORNL; Rearden, Bradley T [ORNL
Quantum Monte Carlo algorithms for electronic structure at the petascale; the endstation project.
Over the past two decades, continuum quantum Monte Carlo (QMC) has proved to be an invaluable tool for predicting of the properties of matter from fundamental principles. By solving the Schrodinger equation through a stochastic projection, it achieves the greatest accuracy and reliability of methods available for physical systems containing more than a few quantum particles. QMC enjoys scaling favorable to quantum chemical methods, with a computational effort which grows with the second or third power of system size. This accuracy and scalability has enabled scientific discovery across a broad spectrum of disciplines. The current methods perform very efficiently at the terascale. The quantum Monte Carlo Endstation project is a collaborative effort among researchers in the field to develop a new generation of algorithms, and their efficient implementations, which will take advantage of the upcoming petaflop architectures. Some aspects of these developments are discussed here. These tools will expand the accuracy, efficiency and range of QMC applicability and enable us to tackle challenges which are currently out of reach. The methods will be applied to several important problems including electronic and structural properties of water, transition metal oxides, nanosystems and ultracold atoms.
Kim, J; Ceperley, D M; Purwanto, W; Walter, E J; Krakauer, H; Zhang, S W; Kent, P.R. C; Hennig, R G; Umrigar, C; Bajdich, M; Kolorenc, J; Mitas, L
Basic physical and chemical information needed for development of Monte Carlo codes
It is important to view track structure analysis as an application of a branch of theoretical physics (i.e., statistical physics and physical kinetics in the language of the Landau school). Monte Carlo methods and transport equation methods represent two major approaches. In either approach, it is of paramount importance to use as input the cross section data that best represent the elementary microscopic processes. Transport analysis based on unrealistic input data must be viewed with caution, because results can be misleading. Work toward establishing the cross section data, which demands a wide scope of knowledge and expertise, is being carried out through extensive international collaborations. In track structure analysis for radiation biology, the need for cross sections for the interactions of electrons with DNA and neighboring protein molecules seems to be especially urgent. Finally, it is important to interpret results of Monte Carlo calculations fully and adequately. To this end, workers should document input data as thoroughly as possible and report their results in detail in many ways. Workers in analytic transport theory are then likely to contribute to the interpretation of the results.
Inokuti, M.
Massively parallel Monte Carlo for many-particle simulations on GPUs
Current trends in parallel processors call for the design of efficient massively parallel algorithms for scientific computing. Parallel algorithms for Monte Carlo simulations of thermodynamic ensembles of particles have received little attention because of the inherent serial nature of the statistical sampling. In this paper, we present a massively parallel method that obeys detailed balance and implement it for a system of hard disks on the GPU. We reproduce results of serial high-precision Monte Carlo runs to verify the method. This is a good test case because the hard disk equation of state over the range where the liquid transforms into the solid is particularly sensitive to small deviations away from the balance conditions. On a Tesla K20, our GPU implementation executes over one billion trial moves per second, which is 148 times faster than on a single Intel Xeon E5540 CPU core, enables 27 times better performance per dollar, and cuts energy usage by a factor of 13. With this improved performance we are able to calculate the equation of state for systems of up to one million hard disks. These large system sizes are required in order to probe the nature of the melting transition, which has been debated for the last forty years. In this paper we present the details of our computational method, and discuss the thermodynamics of hard disks separately in a companion paper.
Joshua A. Anderson; Eric Jankowski; Thomas L. Grubb; Michael Engel; Sharon C. Glotzer
Exploiting symmetries for exponential error reduction in path integral Monte Carlo
The path integral of a quantum system with an exact symmetry can be written as a sum of functional integrals each giving the contribution from quantum states with definite symmetry properties. We propose a strategy to compute each of them, normalized to the one with vacuum quantum numbers, by a Monte Carlo procedure whose cost increases power-like with the time extent of the lattice. This is achieved thanks to a multi-level integration scheme, inspired by the transfer matrix formalism, which exploits the symmetry and the locality in time of the underlying statistical system. As a result the cost of computing the lowest energy level in a given channel, its multiplicity and its matrix elements is exponentially reduced with respect to the standard path-integral Monte Carlo. We test the strategy with a one-dimensional harmonic oscillator, by computing the ratio of the parity odd over the parity even functional integrals and the two-point correlation function. The cost of the simulations scales as expected. In par...
Della Morte, Michele
Electron energy losses near pulsar polar caps: a Monte Carlo approach
We use Monte Carlo approach to study the energetics of electrons accelerated in a pulsar polar gap. As energy-loss mechanisms we consider magnetic Compton scattering of thermal X-ray photons and curvature radiation. The results are compared with previous calculations which assumed that changes of electron energy occurred smoothly according to approximations for the average energy loss rate due to the Compton scattering. We confirm a general dependence of efficiency of electron energy losses due to inverse Compton mechanism on the temperature and size of a thermal polar cap and on the pulsar magnetic field. However, we show that trajectories of electrons in energy-altitude space as calculated in the smooth way do not always coincide with averaged Monte Carlo behaviour. In particular, for pulsars with high magnetic field strength ($B_{pc} > 3\\times 10^{12}$ G) and low thermal polar cap temperatures ($T < 5\\times 10^6$ K) final electron Lorentz factors computed with the two methods may differ by a few orders of magnitude. We discuss consequences for particular objects with identified thermal X-ray spectral components like Geminga, Vela, and PSR B1055-52.
J. Dyks; B. Rudak
Speciation model selection by Monte Carlo analysis of optical absorption spectra: Plutonium(IV) nitrate complexes
Standard modeling approaches can produce the most likely values of the formation constants of metal-ligand complexes if a particular set of species containing the metal ion is known or assumed to exist in solution equilibrium with complexing ligands. Identifying the most likely set of species when more than one set is plausible is a more difficult problem to address quantitatively. A Monte Carlo method of data analysis is described that measures the relative abilities of different speciation models to fit optical spectra of open-shell actinide ions. The best model(s) can be identified from among a larger group of models initially judged to be plausible. The method is demonstrated by analyzing the absorption spectra of aqueous Pu(IV) titrated with nitrate ion at constant 2 molal ionic strength in aqueous perchloric acid. The best speciation model supported by the data is shown to include three Pu(IV) species with nitrate coordination numbers 0, 1, and 2. Formation constants are {beta}{sub 1}=3.2{+-}0.5 and {beta}{sub 2}=11.2{+-}1.2, where the uncertainties are 95% confidence limits estimated by propagating raw data uncertainties using Monte Carlo methods. Principal component analysis independently indicates three Pu(IV) complexes in equilibrium. (c) 2000 Society for Applied Spectroscopy.
Berg, John M. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Veirs, D. Kirk [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Vaughn, Randolph B. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Cisneros, Michael R. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Smith, Coleman A. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Configuration-interaction Monte Carlo method and its application to the trapped unitary Fermi gas
We develop a quantum Monte Carlo method to estimate the ground-state energy of a fermionic many-particle system in the configuration-interaction shell model approach. The fermionic sign problem is circumvented by using a guiding wave function in Fock space. The method provides an upper bound on the ground-state energy whose tightness depends on the choice of the guiding wave function. We argue that the antisymmetric geminal product class of wave functions is a good choice for guiding wave functions. We demonstrate our method for the trapped two-species fermionic cold atom system in the unitary regime of infinite scattering length using the particle-number projected Hartree-Fock-Bogoliubov wave function as the guiding wave function. We estimate the ground-state energy and energy-staggering pairing gap as a function of the number of particles. Our results compare favorably with exact numerical diagonalization results and with previous coordinate-space Monte Carlo calculations.
Mukherjee, Abhishek
Abhishek Mukherjee; Y. Alhassid
Automatic Mesh Adaptivity for Hybrid Monte Carlo/Deterministic Neutronics Modeling of Fusion Energy Systems
Three mesh adaptivity algorithms were developed to facilitate and expedite the use of the CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques in accurate full-scale neutronics simulations of fusion energy systems with immense sizes and complicated geometries. First, a macromaterial approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm decouples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility and resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation. Additionally, because of the significant increase in the efficiency of FW-CADIS simulations, the three algorithms enabled this difficult calculation to be accurately solved on a regular computer cluster, eliminating the need for a world-class super computer.
Ibrahim, Ahmad M [ORNL; Wilson, P. [University of Wisconsin; Sawan, M. [University of Wisconsin; Mosher, Scott W [ORNL; Peplow, Douglas E. [ORNL; Grove, Robert E [ORNL
A Deterministic-Monte Carlo Hybrid Method for Time-Dependent Neutron Transport Problems
A new deterministic-Monte Carlo hybrid solution technique is derived for the time-dependent transport equation. This new approach is based on dividing the time domain into a number of coarse intervals and expanding the transport solution in a series of polynomials within each interval. The solutions within each interval can be represented in terms of arbitrary source terms by using precomputed response functions. In the current work, the time-dependent response function computations are performed using the Monte Carlo method, while the global time-step march is performed deterministically. This work extends previous work by coupling the time-dependent expansions to space- and angle-dependent expansions to fully characterize the 1D transport response/solution. More generally, this approach represents and incremental extension of the steady-state coarse-mesh transport method that is based on global-local decompositions of large neutron transport problems. An example of a homogeneous slab is discussed as an example of the new developments.
Justin Pounders; Farzad Rahnema
Physics and Algorithm Enhancements for a Validated MCNP/X Monte Carlo Simulation Tool, Phase VII
Currently the US lacks an end-to-end (i.e., source-to-detector) radiation transport simulation code with predictive capability for the broad range of DHS nuclear material detection applications. For example, gaps in the physics, along with inadequate analysis algorithms, make it difficult for Monte Carlo simulations to provide a comprehensive evaluation, design, and optimization of proposed interrogation systems. With the development and implementation of several key physics and algorithm enhancements, along with needed improvements in evaluated data and benchmark measurements, the MCNP/X Monte Carlo codes will provide designers, operators, and systems analysts with a validated tool for developing state-of-the-art active and passive detection systems. This project is currently in its seventh year (Phase VII). This presentation will review thirty enhancements that have been implemented in MCNPX over the last 3 years and were included in the 2011 release of version 2.7.0. These improvements include 12 physics enhancements, 4 source enhancements, 8 tally enhancements, and 6 other enhancements. Examples and results will be provided for each of these features. The presentation will also discuss the eight enhancements that will be migrated into MCNP6 over the upcoming year.
McKinney, Gregg W [Los Alamos National Laboratory
Surface Structures of Cubo-octahedral Pt-Mo Catalyst Nanoparticles from Monte Carlo Simulations
The surface structures of cubo-octahedral Pt-Mo nanoparticles have been investigated using the Monte Carlo method and modified embedded atom method potentials that we developed for Pt-Mo alloys. The cubo-octahedral Pt-Mo nanoparticles are constructed with disordered fcc configurations, with sizes from 2.5 to 5.0 nm, and with Pt concentrations from 60 to 90 at. percent. The equilibrium Pt-Mo nanoparticle configurations were generated through Monte Carlo simulations allowing both atomic displacements and element exchanges at 600 K. We predict that the Pt atoms weakly segregate to the surfaces of such nanoparticles. The Pt concentrations in the surface are calculated to be 5 to 14 at. percent higher than the Pt concentrations of the nanoparticles. Moreover, the Pt atoms preferentially segregate to the facet sites of the surface, while the Pt and Mo atoms tend to alternate along the edges and vertices of these nanoparticles. We found that decreasing the size or increasing the Pt concentration leads to higher Pt concentrations but fewer Pt-Mo pairs in the Pt-Mo nanoparticle surfaces.
Wang, Guofeng; Van Hove, M.A.; Ross, P.N.; Baskes, M.I.
An Evaluation of Monte Carlo Simulations of Neutron Multiplicity Measurements of Plutonium Metal
In January 2009, Sandia National Laboratories conducted neutron multiplicity measurements of a polyethylene-reflected plutonium metal sphere. Over the past 3 years, those experiments have been collaboratively analyzed using Monte Carlo simulations conducted by University of Michigan (UM), Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and North Carolina State University (NCSU). Monte Carlo simulations of the experiments consistently overpredict the mean and variance of the measured neutron multiplicity distribution. This paper presents a sensitivity study conducted to evaluate the potential sources of the observed errors. MCNPX-PoliMi simulations of plutonium neutron multiplicity measurements exhibited systematic over-prediction of the neutron multiplicity distribution. The over-prediction tended to increase with increasing multiplication. MCNPX-PoliMi had previously been validated against only very low multiplication benchmarks. We conducted sensitivity studies to try to identify the cause(s) of the simulation errors; we eliminated the potential causes we identified, except for Pu-239 {bar {nu}}. A very small change (-1.1%) in the Pu-239 {bar {nu}} dramatically improved the accuracy of the MCNPX-PoliMi simulation for all 6 measurements. This observation is consistent with the trend observed in the bias exhibited by the MCNPX-PoliMi simulations: a very small error in {bar {nu}} is 'magnified' by increasing multiplication. We applied a scalar adjustment to Pu-239 {bar {nu}} (independent of neutron energy); an adjustment that depends on energy is probably more appropriate.
Mattingly, John [North Carolina State University; Miller, Eric [University of Michigan; Solomon, Clell J. Jr. [Los Alamos National Laboratory; Dennis, Ben [University of Michigan; Meldrum, Amy [University of Michigan; Clarke, Shaun [University of Michigan; Pozzi, Sara [University of Michigan
GUINEVERE experiment: Kinetic analysis of some reactivity measurement methods by deterministic and Monte Carlo codes
The GUINEVERE experiment (Generation of Uninterrupted Intense Neutrons at the lead Venus Reactor) is an experimental program in support of the ADS technology presently carried out at SCK-CEN in Mol (Belgium). In the experiment a modified lay-out of the original thermal VENUS critical facility is coupled to an accelerator, built by the French body CNRS in Grenoble, working in both continuous and pulsed mode and delivering 14 MeV neutrons by bombardment of deuterons on a tritium-target. The modified lay-out of the facility consists of a fast subcritical core made of 30% U-235 enriched metallic Uranium in a lead matrix. Several off-line and on-line reactivity measurement techniques will be investigated during the experimental campaign. This report is focused on the simulation by deterministic (ERANOS French code) and Monte Carlo (MCNPX US code) calculations of three reactivity measurement techniques, Slope ({alpha}-fitting), Area-ratio and Source-jerk, applied to a GUINEVERE subcritical configuration (namely SC1). The inferred reactivity, in dollar units, by the Area-ratio method shows an overall agreement between the two deterministic and Monte Carlo computational approaches, whereas the MCNPX Source-jerk results are affected by large uncertainties and allow only partial conclusions about the comparison. Finally, no particular spatial dependence of the results is observed in the case of the GUINEVERE SC1 subcritical configuration. (authors)
Bianchini, G.; Burgio, N.; Carta, M. [ENEA C.R. CASACCIA, via Anguillarese, 301, 00123 S. Maria di Galeria Roma (Italy); Peluso, V. [ENEA C.R. BOLOGNA, Via Martiri di Monte Sole, 4, 40129 Bologna (Italy); Fabrizio, V.; Ricci, L. [Univ. of Rome La Sapienza, C/o ENEA C.R. CASACCIA, via Anguillarese, 301, 00123 S. Maria di Galeria Roma (Italy)
RunMC - an object-oriented analysis framework for Monte Carlo simulation of high-energy particle collisions
RunMC is an object-oriented framework aimed to generate and to analyse high-energy collisions of elementary particles using Monte Carlo simulations. This package, being based on C++ adopted by CERN as the main programming language for the LHC experiments, provides a common interface to different Monte Carlo models using modern physics libraries. Physics calculations (projects) can easily be loaded and saved as external modules. This simplifies the development of complicated calculations for high energy physics in large collaborations.This desktop program is open-source licensed and is available on the LINUX and Windows/Cygwin platforms.
S. Chekanov
Overview of Geometry Representation in Monte Carlo Codes Ronald P. Kensek
Overview of Geometry Representation Overview of Geometry Representation in Monte Carlo Codes Ronald P. Kensek Brian C. Franke Thomas W. Laub Leonard J. Lorence Matthew R. Martin Sandia National Laboratories Steve Warren Kansas State University Joint Russian-American Five-Laboratory Conference on Computational Mathematics / Physics Vienna, Austria June 19-23, 2005 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States National Nuclear Security Administration and the Department of Energy under contract DE-AC04-94AL85000. 2 Problem Setup: Engineering designs CG vs. CAD Combinatorial Geometry (CG) * Engineering designs are not typically created in this format * No general automatic translation from CAD to CG yet exists * Problem setup is difficult: Creation
State and parameter estimation using Monte Carlo evaluation of path integrals
Transferring information from observations of a dynamical system to estimate the fixed parameters and unobserved states of a system model can be formulated as the evaluation of a discrete time path integral in model state space. The observations serve as a guiding potential working with the dynamical rules of the model to direct system orbits in state space. The path integral representation permits direct numerical evaluation of the conditional mean path through the state space as well as conditional moments about this mean. Using a Monte Carlo method for selecting paths through state space we show how these moments can be evaluated and demonstrate in an interesting model system the explicit influence of the role of transfer of information from the observations. We address the question of how many observations are required to estimate the unobserved state variables, and we examine the assumptions of Gaussianity of the underlying conditional probability.
John C. Quinn; Henry D. I. Abarbanel
Validation of the Monte Carlo Criticality Program KENO V. a for highly-enriched uranium systems
A series of calculations based on critical experiments have been performed using the KENO V.a Monte Carlo Criticality Program for the purpose of validating KENO V.a for use in evaluating Y-12 Plant criticality problems. The experiments were reflected and unreflected systems of single units and arrays containing highly enriched uranium metal or uranium compounds. Various geometrical shapes were used in the experiments. The SCALE control module CSAS25 with the 27-group ENDF/B-4 cross-section library was used to perform the calculations. Some of the experiments were also calculated using the 16-group Hansen-Roach Library. Results are presented in a series of tables and discussed. Results show that the criteria established for the safe application of the KENO IV program may also be used for KENO V.a results.
Knight, J.R.
Suppressing nonphysical overheating with a modified implicit Monte Carlo method for time-dependent radiative transfer
In this note we develop a robust implicit Monte Carlo (IMC) algorithm based on more accurately updating the linearized equilibrium radiation energy density. The method does not introduce oscillations in the solution and has the same limit as {Delta}t{yields}{infinity} as the standard Fleck and Cummings IMC method. Moreover, the approach we introduce can be trivially added to current implementations of IMC by changing the definition of the Fleck factor. Using this new method we develop an adaptive scheme that uses either standard IMC or the modified method basing the adaptation on a zero-dimensional problem solved in each cell. Numerical results demonstrate that the new method alleviates both the nonphysical overheating that occurs in standard IMC when the time step is large and significantly diminishes the statistical noise in the solution.
Mcclarren, Ryan G [Los Alamos National Laboratory; Urbatsch, Todd J [Los Alamos National Laboratory
Cation dopant distributions in nanostructures of transition-metal doped ZnO:Monte Carlo simulations
The path from trace doping to solid solution formation involves an intermediate regime in which the doping level is a few to several atomic percent. In this regime, dopant-dopant interactions, which are driven by the spatial arrangement of dopants, are critical factors in determining the resulting properties. Conventional wisdom counts on simple probabilistic methods for predicting dopant distributions. Here, we use Monte Carlo simulations to show that widely used, straightforward statistical models, such as that of Behringer1, are accurate only in the limit of infinitesimally small surface�to-volume ratio. For epitaxial films and nanoparticles, where much of the current interest resides, dopant distributions depend strongly on the surface-to-volume ratio. We present empirical expressions that accurately predict dopant bonding configurations as a function of film or particle size, shape and dopant concentration for doped ZnO, a material of particular interest in semiconductor spintronics.
Droubay, Timothy; Kaspar, Tiffany C.; Kaspar, Bryce P.; Chambers, Scott A.
Local Monte Carlo Implementation of the Non-Abelian Landau-Pomeranchuk-Migdal Effect
The non-Abelian Landau-Pomeranschuk-Migdal (LPM) effect arises from the quantum interference between spatially separated, inelastic radiation processes in matter. A consistent probabilistic implementation of this LPM effect is a prerequisite for extending the use of Monte Carlo (MC) event generators to the simulation of jetlike multiparticle final states in nuclear collisions. Here, we propose a local MC algorithm, which is based solely on relating the LPM effect to the probabilistic concept of formation time for virtual quanta. This accounts probabilistically for the characteristic L{sup 2} dependence of average parton energy loss and the characteristic 1/sq root(omega) modification of the non-Abelian LPM effect. Additional kinematic constraints are found to modify these L{sup 2} and omega dependencies characteristically in accordance with analytical estimates.
Zapp, Korinna [Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany); EMMI, GSI Helmholtz-Institut fuer Ionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany); Stachel, Johanna [Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany); Wiedemann, Urs Achim [Physics Department, Theory Unit, CERN, CH-1211 Geneve 23 (Switzerland)
Improving computational efficiency of Monte-Carlo simulations with variance reduction
CCFE perform Monte-Carlo transport simulations on large and complex tokamak models such as ITER. Such simulations are challenging since streaming and deep penetration effects are equally important. In order to make such simulations tractable, both variance reduction (VR) techniques and parallel computing are used. It has been found that the application of VR techniques in such models significantly reduces the efficiency of parallel computation due to 'long histories'. VR in MCNP can be accomplished using energy-dependent weight windows. The weight window represents an 'average behaviour' of particles, and large deviations in the arriving weight of a particle give rise to extreme amounts of splitting being performed and a long history. When running on parallel clusters, a long history can have a detrimental effect on the parallel efficiency - if one process is computing the long history, the other CPUs complete their batch of histories and wait idle. Furthermore some long histories have been found to be effect...
Turner, A
Dynamic Monte Carlo simulation of coupled transport through a narrow multiply-occupied pore
Dynamic Monte Carlo simulations are used to study coupled transport (co-transport) through sub-nanometer-diameter pores. In this classic Hodgkin-Keynes mechanism, an ion species uses the large flux of an abundant ion species to move against its concentration gradient. The efficiency of co-transport is examined for various pore parameters so that synthetic nanopores can be engineered to maximize this effect. In general, the pore must be narrow enough that ions cannot pass each other and the charge of the pore large enough to attract many ions so that they exchange momentum. Co-transport efficiency increases as pore length increases, but even very short pores exhibit co-transport, in contradiction to the usual perception that long pores are necessary. The parameter ranges where co-transport occurs is consistent with current and near-future synthetic nanopore geometry parameters, suggesting that co-transport of ions may be a new application of nanopores.
Dezs? Boda; �va Cs�nyi; Dirk Gillespie; Tam�s Krist�f
Coupled coarse graining and Markov Chain Monte Carlo for lattice systems
We propose an efficient Markov Chain Monte Carlo method for sampling equilibrium distributions for stochastic lattice models, capable of handling correctly long and short-range particle interactions. The proposed method is a Metropolis-type algorithm with the proposal probability transition matrix based on the coarse-grained approximating measures introduced in a series of works of M. Katsoulakis, A. Majda, D. Vlachos and P. Plechac, L. Rey-Bellet and D.Tsagkarogiannis,. We prove that the proposed algorithm reduces the computational cost due to energy differences and has comparable mixing properties with the classical microscopic Metropolis algorithm, controlled by the level of coarsening and reconstruction procedure. The properties and effectiveness of the algorithm are demonstrated with an exactly solvable example of a one dimensional Ising-type model, comparing efficiency of the single spin-flip Metropolis dynamics and the proposed coupled Metropolis algorithm.
Kalligiannaki, Evangelia; Plechac, Petr
Study of CANDU thorium-based fuel cycles by deterministic and Monte Carlo methods
In the framework of the Generation IV forum, there is a renewal of interest in self-sustainable thorium fuel cycles applied to various concepts such as Molten Salt Reactors [1, 2] or High Temperature Reactors [3, 4]. Precise evaluations of the U-233 production potential relying on existing reactors such as PWRs [5] or CANDUs [6] are hence necessary. As a consequence of its design (online refueling and D{sub 2}O moderator in a thermal spectrum), the CANDU reactor has moreover an excellent neutron economy and consequently a high fissile conversion ratio [7]. For these reasons, we try here, with a shorter term view, to re-evaluate the economic competitiveness of once-through thorium-based fuel cycles in CANDU [8]. Two simulation tools are used: the deterministic Canadian cell code DRAGON [9] and MURE [10], a C++ tool for reactor evolution calculations based on the Monte Carlo code MCNP [11]. (authors)
Nuttin, A.; Guillemin, P. [LPSC Grenoble ENSPG (France); Courau, T. [EDF R and D Clamart (France); Marleau, G. [Ecole Polytechnique de Montreal (Canada); Meplan, O. [LPSC Grenoble UJF (France); David, S.; Michel-Sendis, F.; Wilson, J. N. [IPN Orsay CNRS (France)
Converting Boundary Representation Solid Models to Half-Space Representation Models for Monte Carlo Analysis
Solid modeling computer software systems provide for the design of three-dimensional solid models used in the design and analysis of physical components. The current state-of-the-art in solid modeling representation uses a boundary representation format in which geometry and topology are used to form three-dimensional boundaries of the solid. The geometry representation used in these systems is cubic B-spline curves and surfaces--a network of cubic B-spline functions in three-dimensional Cartesian coordinate space. Many Monte Carlo codes, however, use a geometry representation in which geometry units are specified by intersections and unions of half-spaces. This paper describes an algorithm for converting from a boundary representation to a half-space representation.
Davis JE, Eddy MJ, Sutton TM, Altomari TJ
MaGe - a Geant4-based Monte Carlo framework for low-background experiments
A Monte Carlo framework, MaGe, has been developed based on the Geant4 simulation toolkit. Its purpose is to simulate physics processes in low-energy and low-background radiation detectors, specifically for the Majorana and Gerda $^{76}$Ge neutrinoless double-beta decay experiments. This jointly-developed tool is also used to verify the simulation of physics processes relevant to other low-background experiments in Geant4. The MaGe framework contains simulations of prototype experiments and test stands, and is easily extended to incorporate new geometries and configurations while still using the same verified physics processes, tunings, and code framework. This reduces duplication of efforts and improves the robustness of and confidence in the simulation output.
Yuen-Dat Chan; Jason A. Detwiler; Reyco Henning; Victor M. Gehman; Rob A. Johnson; David V. Jordan; Kareem Kazkaz; Markus Knapp; Kevin Kroninger; Daniel Lenz; Jing Liu; Xiang Liu; Michael G. Marino; Akbar Mokhtarani; Luciano Pandola; Alexis G. Schubert; Claudia Tomei
MC++: A parallel, portable, Monte Carlo neutron transport code in C++
MC++ is an implicit multi-group Monte Carlo neutron transport code written in C++ and based on the Parallel Object-Oriented Methods and Applications (POOMA) class library. MC++ runs in parallel on and is portable to a wide variety of platforms, including MPPs, SMPs, and clusters of UNIX workstations. MC++ is being developed to provide transport capabilities to the Accelerated Strategic Computing Initiative (ASCI). It is also intended to form the basis of the first transport physics framework (TPF), which is a C++ class library containing appropriate abstractions, objects, and methods for the particle transport problem. The transport problem is briefly described, as well as the current status and algorithms in MC++ for solving the transport equation. The alpha version of the POOMA class library is also discussed, along with the implementation of the transport solution algorithms using POOMA. Finally, a simple test problem is defined and performance and physics results from this problem are discussed on a variety of platforms.
Lee, S.R.; Cummings, J.C. [Los Alamos National Lab., NM (United States); Nolen, S.D. [Texas A & M Univ., College Station, TX (United States)
A Monte-Carlo method for ex-core neutron response
A Monte Carlo neutron transport kernel capability primarily for ex-core neutron response is described. The capability consists of the generation of a set of response kernels, which represent the neutron transport from the core to a specific ex-core volume. This is accomplished by tagging individual neutron histories from their initial source sites and tracking them throughout the problem geometry, tallying those that interact in the geometric regions of interest. These transport kernels can subsequently be combined with any number of core power distributions to determine detector response for a variety of reactor Thus, the transport kernels are analogous to an integrated adjoint response. Examples of pressure vessel response and ex-core neutron detector response are provided to illustrate the method.
Gamino, R.G.; Ward, J.T.; Hughes, J.C. [Lockheed Martin Corp., Schenectady, NY (United States)
Frozen-orbital and downfolding calculations with auxiliary-field quantum Monte Carlo
We describe the implementation of the frozen-orbital and downfolding approximations in the auxiliary-field quantum Monte Carlo (AFQMC) method. These approaches can provide significant computational savings compared to fully correlating all the electrons. While the many-body wave function is never explicit in AFQMC, its random walkers are Slater determinants, whose orbitals may be expressed in terms of any one-particle orbital basis. It is therefore straightforward to partition the full N-particle Hilbert space into active and inactive parts to implement the frozen-orbital method. In the frozen-core approximation, for example, the core electrons can be eliminated in the correlated part of the calculations, greatly increasing the computational efficiency, especially for heavy atoms. Scalar relativistic effects are easily included using the Douglas-Kroll-Hess theory. Using this method, we obtain a way to effectively eliminate the error due to single-projector, norm-conserving pseudopotentials in AFQMC. We also i...
Purwanto, Wirawan; Krakauer, Henry
Monte Carlo calculation of the transition temperature of the anisotropic three-dimensional {ital XY} model
The transition temperature of the spatially anisotropic three-dimensional classical {ital XY} model is calculated by means of Monte Carlo (MC) simulations. In the {ital XY} model the spins are not restricted to the {ital XY} plane, as in the plane rotator model. The results are compared with a self-consistent harmonic approximation calculation (SCHA). In two dimensions the inclusion of effect of vortices pushes down the transition temperature from {ital T}{sub KT}/{ital J}=1.08, given by the standard SCHA to {ital T}{sub KT}/{ital J}=0.70, in good agreement with the MC estimate {ital T}{sub KT}/{ital J}=0.725. {copyright} {ital 1996 The American Physical Society.}
Costa, B.V.; Pereira, A.R.; Pires, A.S. [Departamento de Fisica, Universidade Federal de Minas Gerais, CP 702, Belo Horizonte, 30161970 Minas Gerais (Brazil)] [Departamento de Fisica, Universidade Federal de Minas Gerais, CP 702, Belo Horizonte, 30161970 Minas Gerais (Brazil)
Monte Carlo simulation of ion trajectories in the modified PDX thermal charge exchange analyzer
An improved design for the present PDX thermal charge exchange analyzer (MACE) has been proposed by one of the authors, in which the five cylindrical electrostatic plates for mass separation are replaced by a single flat, electrostatic deflection plate. An existihg Monte Carlo code that simulated the passage of ions through the MACE analyzer was modified to examine the feasibility of this change. The resulting calculations were used to optimize detector positions and collimation requirements. The first analyzer to be placed on PDX will be of the old design, similar to the present PLT analyzer. However, if the design reported here is successful on the test stand, the future PDX analyzers will all be of the new, single electrostatic plate variety. A further advantage will be the ability to install as many as ten detectors instead of the current five, thus providing twice as many energy channels for each shot. Also, both mass species (H, D) can be measured concurrently, if desired.
Kaita, R.; Davis, S.L.; Medley, S.S.
Investigation of a V{sub 15} magnetic molecular nanocluster by the Monte Carlo method
Exchange interactions in a V{sub 15} magnetic molecular nanocluster are considered, and the process of magnetization reversal for various values of the set of exchange constants is analyzed by the Monte Carlo method. It is shown that the best agreement between the field dependence of susceptibility and experimental results is observed for the following set of exchange interaction constants in a V{sub 15} magnetic molecular nanocluster: J = 500 K, J Prime = 150 K, J Double-Prime = 225 K, J{sub 1} = 50 K, and J{sub 2} = 50 K. It is observed for the first time that, in a strong magnetic field, for each of the three transitions from low-spin to high-spin states, the heat capacity exhibits two closely spaced maxima.
Khizriev, K. Sh., E-mail: firstname.lastname@example.com [Russian Academy of Sciences, Kh.I. Amirkhanov Institute of Physics, Dagestan Scientific Center (Russian Federation); Dzhamalutdinova, I. S.; Taaev, T. A. [Dagestan State University (Russian Federation)
Bayesian Inference for LISA Pathfinder using Markov Chain Monte Carlo Methods
We present a parameter estimation procedure based on a Bayesian framework by applying a Markov Chain Monte Carlo algorithm to the calibration of the dynamical parameters of a space based gravitational wave detector. The method is based on the Metropolis-Hastings algorithm and a two-stage annealing treatment in order to ensure an effective exploration of the parameter space at the beginning of the chain. We compare two versions of the algorithm with an application to a LISA Pathfinder data analysis problem. The two algorithms share the same heating strategy but with one moving in coordinate directions using proposals from a multivariate Gaussian distribution, while the other uses the natural logarithm of some parameters and proposes jumps in the eigen-space of the Fisher Information matrix. The algorithm proposing jumps in the eigen-space of the Fisher Information matrix demonstrates a higher acceptance rate and a slightly better convergence towards the equilibrium parameter distributions in the application to...
Ferraioli, Luigi; Plagnol, Eric
A Markov-Chain Monte-Carlo Based Method for Flaw Detection in Beams
A Bayesian inference methodology using a Markov Chain Monte Carlo (MCMC) sampling procedure is presented for estimating the parameters of computational structural models. This methodology combines prior information, measured data, and forward models to produce a posterior distribution for the system parameters of structural models that is most consistent with all available data. The MCMC procedure is based upon a Metropolis-Hastings algorithm that is shown to function effectively with noisy data, incomplete data sets, and mismatched computational nodes/measurement points. A series of numerical test cases based upon a cantilever beam is presented. The results demonstrate that the algorithm is able to estimate model parameters utilizing experimental data for the nodal displacements resulting from specified forces.
Glaser, R E; Lee, C L; Nitao, J J; Hickling, T L; Hanley, W G
Monte-Carlo study of quasiparticle dispersion relation in monolayer graphene
The density of electronic one-particle states in monolayer graphene is studied by performing the Hybrid Monte-Carlo simulations of the tight-binding model for electrons on the pi orbitals of carbon atoms which make up the graphene lattice. Density of states is approximated as a derivative of the number of particles over the chemical potential at sufficiently small temperature. Simulations are performed in the partially quenched approximation, in which virtual particles and holes have zero chemical potential. It is found that the Van Hove singularity becomes much sharper than in the free tight-binding model. Simulation results also suggest that the Fermi velocity increases with interaction strength up to the transition to the phase with spontaneously broken chiral symmetry.
P. V. Buividovich
Hybrid Monte-Carlo simulation of interacting tight-binding model of graphene
In this work, results are presented of Hybrid-Monte-Carlo simulations of the tight-binding Hamiltonian of graphene, coupled to an instantaneous long-range two-body potential which is modeled by a Hubbard-Stratonovich auxiliary field. We present an investigation of the spontaneous breaking of the sublattice symmetry, which corresponds to a phase transition from a conducting to an insulating phase and which occurs when the effective fine-structure constant $\\alpha$ of the system crosses above a certain threshold $\\alpha_C$. Qualitative comparisons to earlier works on the subject (which used larger system sizes and higher statistics) are made and it is established that $\\alpha_C$ is of a plausible magnitude in our simulations. Also, we discuss differences between simulations using compact and non-compact variants of the Hubbard field and present a quantitative comparison of distinct discretization schemes of the Euclidean time-like dimension in the Fermion operator.
Dominik Smith; Lorenz von Smekal
Monte Carlo based dosimetry and treatment planning for neutron capture therapy of brain tumors
Monte Carlo based dosimetry and computer-aided treatment planning for neutron capture therapy have been developed to provide the necessary link between physical dosimetric measurements performed on the MITR-II epithermal-neutron beams and the need of the radiation oncologist to synthesize large amounts of dosimetric data into a clinically meaningful treatment plan for each individual patient. Monte Carlo simulation has been employed to characterize the spatial dose distributions within a skull/brain model irradiated by an epithermal-neutron beam designed for neutron capture therapy applications. The geometry and elemental composition employed for the mathematical skull/brain model and the neutron and photon fluence-to-dose conversion formalism are presented. A treatment planning program, NCTPLAN, developed specifically for neutron capture therapy, is described. Examples are presented illustrating both one and two-dimensional dose distributions obtainable within the brain with an experimental epithermal-neutron beam, together with beam quality and treatment plan efficacy criteria which have been formulated for neutron capture therapy. The incorporation of three-dimensional computed tomographic image data into the treatment planning procedure is illustrated. The experimental epithermal-neutron beam has a maximum usable circular diameter of 20 cm, and with 30 ppm of B-10 in tumor and 3 ppm of B-10 in blood, it produces a beam-axis advantage depth of 7.4 cm, a beam-axis advantage ratio of 1.83, a global advantage ratio of 1.70, and an advantage depth RBE-dose rate to tumor of 20.6 RBE-cGy/min (cJ/kg-min). These characteristics make this beam well suited for clinical applications, enabling an RBE-dose of 2,000 RBE-cGy/min (cJ/kg-min) to be delivered to tumor at brain midline in six fractions with a treatment time of approximately 16 minutes per fraction.
Zamenhof, R.G.; Clement, S.D.; Harling, O.K.; Brenner, J.F.; Wazer, D.E.; Madoc-Jones, H.; Yanch, J.C. (Tufts-New England Medical Center, Boston, MA (USA))
Monte Carlo Electromagnetic Cross Section Production Method for Low Energy Charged Particle Transport Through Single Molecules
The present state of modeling radio-induced effects at the cellular level neglects to account for the microscopic inhomogeneity of the nucleus from the non-aqueous contents by approximating the entire cellular nucleus as a homogenous medium of water. Charged particle track-structure calculations utilizing this principle of superposition are thereby neglecting to account for approximately 30% of the molecular variation within the nucleus. To truly understand what happens when biological matter is irradiated, charged particle track-structure calculations need detailed knowledge of the secondary electron cascade, resulting from interactions with not only the primary biological component � water � but also the non-aqueous contents, down to very low energies. This paper presents developments for a novel approach, which to our knowledge has never been done before, to reducing the homogenous water approximation. The purpose of our work is to develop of a completely self-consistent computational method for predicting molecule-specific ionization, excitation, and scattering cross sections in the very low energy regime that can be applied in a condensed history Monte Carlo track-structure code. The present methodology begins with the calculation of a solution to the many-body Schr�dinger equation and proceeds to use Monte Carlo methods to calculate the perturbations in the internal electron field to determine the aforementioned processes. Results are computed for molecular water in the form of linear energy loss, secondary electron energies, and ionization-to-excitation ratios and compared against the low energy predictions of the GEANT4-DNA physics package of the Geant4 simulation toolkit.
Madsen, Jonathan R
Using Markov Chain Monte Carlo to quantify parameter uncertainty and its effect on predictions of a groundwater flow model
A statistical Bayesian framework is used to solve the inverse problem and develop the posterior distributions of parameters for a density-driven groundwater flow model. This Bayesian approach is implemented using a Markov Chain Monte Carlo (MCMC) sampling ... Keywords: Conditioning, Groundwater model calibration, Inverse problems, MCMC, Numerical modelling
Ahmed E. Hassan; Hesham M. Bekhit; Jenny B. Chapman
Abstract--The paper focuses on reliability assessment of power systems with wind power generation. A Monte Carlo based
. A Monte Carlo based production cost simulation model is introduced in the paper. The model closely for wind power can be established. Over the years, analytical methods [2]-[4] had been extensively utilized based production cost simulation model had been investigated and developed. The model simulates
McCalley, James D.
Graphs of the cross sections in the recommended Monte Carlo cross-section library at the Los Alamos Scientific Laboratory
Graphs of all neutron cross sections and photon production cross sections on the Recommended Monte Carlo Cross Section (RMCCS) library have been plotted along with local neutron heating numbers. Values for anti ..nu.., the average number of neutrons per fission, are also given.
Soran, P.D.; Seamon, R.E.
The sizes and powers of some stochastic dominance tests: A Monte Carlo study for correlated and heteroskedastic distributions
Testing for stochastic dominance among distributions is an important issue in the study of asset management, income inequality, and market efficiency. This paper conducts Monte Carlo simulations to examine the sizes and powers of several commonly used ... Keywords: C12, Correlated distributions, D31, G11, Grid points, Heteroskedasticity, Stochastic dominance
Hooi-Hooi Lean; Wing-Keung Wong; Xibin Zhang
Study of Horizontally Oriented Ice Crystals with CALIPSO Observations and Comparison with Monte Carlo Radiative Transfer Simulations
Study of Horizontally Oriented Ice Crystals with CALIPSO Observations and Comparison with Monte oriented ice crystals (HOIC) occur frequently in both ice and mixed-phase clouds. When compared with the case for clouds consisting of randomly oriented ice crystals (ROIC), lidar measurements from clouds
Baum, Bryan A.
The estimation techniques of the time series correlations in nuclear reactor calculations by the Monte Carlo method using multiprocessor computers
The algorithms of estimation of the time series correlation functions in nuclear reactor calculations using the Monte Carlo method are described. Correlation functions are used for the estimation of biases, for calculations of variance taking into account the correlations between neutron generations, and for choosing skipped generations.
Kalugin, M. A.; Oleynik, D. S.; Sukhino-Khomenko, E. A., E-mail: firstname.lastname@example.com [National Research Centre Kurchatov Institute (Russian Federation)
Analytical Solution of a Simplified Transport Problem with Continuous Energy for Testing Monte Carlo Procedures,� this conference
A simplified transport problem is presented with continuous energy and neutrons moving only into the +X and �X direction. An exact analytical solution is given with a 1/E energy dependence of the space, direction and energy dependent neutron flux. The source function, which also behaves basically as 1/E has to be modified for a certain energy range if a maximum energy is introduced in the problem. At the cost of more complicated mathematics the total and scattering cross sections and the anisotropy of scattering may very with energy. This model can be implemented in a general purpose Monte Carlo code like MCNP5 without modification, but needs a specially prepared cross section library file. The model can be applied to test Monte Carlo procedures, like the generation of multi-group cross section and scattering matrices which can be calculated analytically from the continuous-energy cross section data. From the adjoint equation the optimum importance function can be derived, which can be used to devise a continuous-energy zero-variance Monte Carlo scheme. Key Words: transport problem, analytical solution, continuous energy, Monte Carlo 1.
J. Eduard Hoogenboom
Research article: Monte Carlo-based rigid body modelling of large protein complexes against small angle scattering data
We present a modular, collaborative, open-source architecture for rigid body modelling based upon small angle scattering data, named sas_rigid. It is designed to provide a fast and extensible scripting interface using the easy-to-learn Python programming ... Keywords: Hemocyanin, Monte Carlo with simulated annealing, Rigid body modelling, Small angle scattering (SAS)
Christian Meesters; Bruno Pairet; Anja Rabenhorst; Heinz Decker; Elmar Jaenicke
Senior Design Project Topics 2011 Project Title: Monte Carlo Simulations Using a Benchmark Full-Core Pressured Water
of approaches in parallel high performance computing that can potentially address the need to accelerate Monte level of 2.57 petaFLOPS by harvesting the power of 14,336 CPUs and 7,168 GPUs. The high performance computing industry is moving toward a hybrid computer model, where GPUs and CPUs work together to perform
Danon, Yaron
Building Energy Software Tools Directory: OptoMizer
with purchase. Weaknesses Does not include mechanical energy auditing functionality (HVAC, pumps, etc.). Contact Company: Fielding Data Labs Address: 324 Monte Vista Irvine,...
Lattice Monte Carlo calculations for unitary fermions in a harmonic trap
We present a lattice Monte Carlo approach developed for studying large numbers of strongly interacting nonrelativistic fermions and apply it to a dilute gas of unitary fermions confined to a harmonic trap. In place of importance sampling, our approach makes use of high statistics, an improved action, and recently proposed statistical techniques. We show how improvement of the lattice action can remove discretization and finite volume errors systematically. For N=3 unitary fermions in a box, our errors in the energy scale as the inverse lattice volume, and we reproduce a previous high-precision benchmark calculation to within our 0.3% uncertainty; as additional benchmarks we reproduce precision calculations of N=3,...,6 unitary fermions in a harmonic trap to within our {approx}1% uncertainty. We then use this action to determine the ground-state energies of up to 70 unpolarized fermions trapped in a harmonic potential on a lattice as large as 64{sup 3}x72. In contrast to variational calculations, we find evidence for persistent deviations from the thermodynamic limit for the range of N considered.
Endres, Michael G.; Kaplan, David B.; Lee, Jong-Wan; Nicholson, Amy N. [Physics Department, Columbia University, New York, New York 10027 (United States); Theoretical Research Division, RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550 (United States)
An Event-Driven Hybrid Molecular Dynamics and Direct Simulation Monte Carlo Algorithm
A novel algorithm is developed for the simulation of polymer chains suspended in a solvent. The polymers are represented as chains of hard spheres tethered by square wells and interact with the solvent particles with hard core potentials. The algorithm uses event-driven molecular dynamics (MD) for the simulation of the polymer chain and the interactions between the chain beads and the surrounding solvent particles. The interactions between the solvent particles themselves are not treated deterministically as in event-driven algorithms, rather, the momentum and energy exchange in the solvent is determined stochastically using the Direct Simulation Monte Carlo (DSMC) method. The coupling between the solvent and the solute is consistently represented at the particle level, however, unlike full MD simulations of both the solvent and the solute, the spatial structure of the solvent is ignored. The algorithm is described in detail and applied to the study of the dynamics of a polymer chain tethered to a hard wall subjected to uniform shear. The algorithm closely reproduces full MD simulations with two orders of magnitude greater efficiency. Results do not confirm the existence of periodic (cycling) motion of the polymer chain.
Donev, A; Garcia, A L; Alder, B J
We develop an asynchronous event-driven First-Passage Kinetic Monte Carlo (FPKMC) algorithm for continuous time and space systems involving multiple diffusing and reacting species of spherical particles in two and three dimensions. The FPKMC algorithm presented here is based on the method introduced in Oppelstrup et al. and is implemented in a robust and flexible framework. Unlike standard KMC algorithms such as the n-fold algorithm, FPKMC is most efficient at low densities where it replaces the many small hops needed for reactants to find each other with large first-passage hops sampled from exact time-dependent Green's functions, without sacrificing accuracy. We describe in detail the key components of the algorithm, including the event-loop and the sampling of first-passage probability distributions, and demonstrate the accuracy of the new method. We apply the FPKMC algorithm to the challenging problem of simulation of long-term irradiation of metals, relevant to the performance and aging of nuclear materials in current and future nuclear power plants. The problem of radiation damage spans many decades of time-scales, from picosecond spikes caused by primary cascades, to years of slow damage annealing and microstructure evolution. Our implementation of the FPKMC algorithm has been able to simulate the irradiation of a metal sample for durations that are orders of magnitude longer than any previous simulations using the standard Object KMC or more recent asynchronous algorithms.
Donev, Aleksandar [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)], E-mail: email@example.com; Bulatov, Vasily V. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Oppelstrup, Tomas [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Royal Institute of Technology (KTH), Stockholm S-10044 (Sweden); Gilmer, George H.; Sadigh, Babak; Kalos, Malvin H. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)
Statistical Properties of Nuclei by the Shell Model Monte Carlo Method
We use quantum Monte Carlo methods in the framework of the interacting nuclear shell model to calculate the statistical properties of nuclei at finite temperature and/or excitation energies. With this approach we can carry out realistic calculations in much larger configuration spaces than are possible by conventional methods. A major application of the methods has been the microscopic calculation of nuclear partition functions and level densities, taking into account both correlations and shell effects. Our results for nuclei in the mass region A ~ 50 - 70 are in remarkably good agreement with experimental level densities without any adjustable parameters and are an improvement over empirical formulas. We have recently extended the shell model theory of level statistics to higher temperatures, including continuum effects. We have also constructed simple statistical models to explain the dependence of the microscopically calculated level densities on good quantum numbers such as parity. Thermal signatures of pairing correlations are identified through odd-even effects in the heat capacity.
Y. Alhassid
Monte Carlo simulation of photon buildup factors for shielding materials in diagnostic x-ray facilities
Purpose: A simulation of buildup factors for ordinary concrete, steel, lead, plate glass, lead glass, and gypsum wallboard in broad beam geometry for photons energies from 10 keV to 150 keV at 5 keV intervals is presented. Methods: Monte Carlo N-particle radiation transport computer code has been used to determine the buildup factors for the studied shielding materials. Results: An example concretizing the use of the obtained buildup factors data in computing the broad beam transmission for tube potentials at 70, 100, 120, and 140 kVp is given. The half value layer, the tenth value layer, and the equilibrium tenth value layer are calculated from the broad beam transmission for these tube potentials. Conclusions: The obtained values compared with those calculated from the published data show the ability of these data to predict shielding transmission curves. Therefore, the buildup factors data can be combined with primary, scatter, and leakage x-ray spectra to provide a computationally based solution to broad beam transmission for barriers in shielding x-ray facilities.
Kharrati, Hedi; Agrebi, Amel; Karoui, Mohamed Karim [Ecole Superieure des Sciences et Techniques de la Sante de Monastir, Avenue Avicenne, 5000 Monastir (Tunisia); Faculte des Sciences de Monastir, 5000 Monastir (Tunisia)
A Monte Carlo method of evaluating heterogeneous effects in plate-fueled reactors
Few-group nuclear cross sections for small plate-fueled, light and heavy water test reactors are frequently generated with unit cell models that contain a homogeneous mixture of fuel, cladding, and water. The heterogeneous unit cells do not need to be represented explicitly for neutronics calculations when the plate and coolant channel thicknesses are small compared with the mean-free-path of neutrons. However, neutron and photon heating calculations were performed with heterogeneous fuel models to predict accurately the heat deposited in the fuel meat, cladding, and coolant. Heat deposited in the coolant channels and outside the fuel elements does not have a direct impact on the peak fuel meat temperature but must be included in the total coolant system heat balance. The results of a heterogeneous Monte Carlo calculation that estimates the heat loads in different fuel regions are presented and the fact that similar homogeneous fuel models can be used for many calculations. The calculations presented here were performed on models of the Advanced Neutron Source (ANS) and the Massachusetts Institute of Technology Reactor 2 (MITR-2). The ANS is a small, 362-MW (fission), plate-fueled, heavy water reactor designed to produce an intense steady-state source of neutrons.
Thayer, R.C.; Redmond, E.L. II; Ryskamp, J.M. (Idaho National Engineering Lab., Idaho Falls (United States))
ITS Version 6 : the integrated TIGER series of coupled electron/photon Monte Carlo transport codes.
ITS is a powerful and user-friendly software package permitting state-of-the-art Monte Carlo solution of lineartime-independent coupled electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fields of arbitrary spatial dependence. Our goal has been to simultaneously maximize operational simplicity and physical accuracy. Through a set of preprocessor directives, the user selects one of the many ITS codes. The ease with which the makefile system is applied combines with an input scheme based on order-independent descriptive keywords that makes maximum use of defaults and internal error checking to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Physical rigor is provided by employing accurate cross sections, sampling distributions, and physical models for describing the production and transport of the electron/photon cascade from 1.0 GeV down to 1.0 keV. The availability of source code permits the more sophisticated user to tailor the codes to specific applications and to extend the capabilities of the codes to more complex applications. Version 6, the latest version of ITS, contains (1) improvements to the ITS 5.0 codes, and (2) conversion to Fortran 90. The general user friendliness of the software has been enhanced through memory allocation to reduce the need for users to modify and recompile the code.
Franke, Brian Claude; Kensek, Ronald Patrick; Laub, Thomas William
Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC): Fundamentals and Applications
The fundamentals of the framework and the details of each component of the self-evolving atomistic kinetic Monte Carlo (SEAKMC) are presented. The strength of this new technique is the ability to simulate dynamic processes with atomistic fidelity that is comparable to molecular dynamics (MD) but on a much longer time scale. The observation that the dimer method preferentially finds the saddle point (SP) with the lowest energy is investigated and found to be true only for defects with high symmetry. In order to estimate the fidelity of dynamics and accuracy of the simulation time, a general criterion is proposed and applied to two representative problems. Applications of SEAKMC for investigating the diffusion of interstitials and vacancies in bcc iron are presented and compared directly with MD simulations, demonstrating that SEAKMC provides results that formerly could be obtained only through MD. The correlation factor for interstitial diffusion in the dumbbell configuration, which is extremely difficult to obtain using MD, is predicted using SEAKMC. The limitations of SEAKMC are also discussed. The paper presents a comprehensive picture of the SEAKMC method in both its unique predictive capabilities and technically important details.
Xu, Haixuan [ORNL; Osetskiy, Yury N [ORNL; Stoller, Roger E [ORNL
A high-fidelity Monte Carlo evaluation of CANDU-6 safety parameters
Important safety parameters such as the fuel temperature coefficient (FTC) and the power coefficient of reactivity (PCR) of the CANDU-6 (CANada Deuterium Uranium) reactor have been evaluated by using a modified MCNPX code. For accurate analysis of the parameters, the DBRC (Doppler Broadening Rejection Correction) scheme was implemented in MCNPX in order to account for the thermal motion of the heavy uranium nucleus in the neutron-U scattering reactions. In this work, a standard fuel lattice has been modeled and the fuel is depleted by using the MCNPX and the FTC value is evaluated for several burnup points including the mid-burnup representing a near-equilibrium core. The Doppler effect has been evaluated by using several cross section libraries such as ENDF/B-VI, ENDF/B-VII, JEFF, JENDLE. The PCR value is also evaluated at mid-burnup conditions to characterize safety features of equilibrium CANDU-6 reactor. To improve the reliability of the Monte Carlo calculations, huge number of neutron histories are considered in this work and the standard deviation of the k-inf values is only 0.5{approx}1 pcm. It has been found that the FTC is significantly enhanced by accounting for the Doppler broadening of scattering resonance and the PCR are clearly improved. (authors)
Kim, Y.; Hartanto, D. [Korea Advanced Inst. of Science and Technology KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of)
Monte Carlo next-event point flux estimation for RCP01
Two next event point estimators have been developed and programmed into the RCP01 Monte Carlo program for solving neutron transport problems in three-dimensional geometry with detailed energy description. These estimators use a simplified but accurate flux-at-a-point tallying technique. Anisotropic scattering in the lab system at the collision site is accounted for by determining the exit energy that corresponds to the angle between the location of the collision and the point detector. Elastic, inelastic, and thermal kernel scattering events are included in this formulation. An averaging technique is used in both estimators to eliminate the well-known problem of infinite variance due to collisions close to the point detector. In a novel approach to improve the estimator`s efficiency, a Russian roulette scheme based on anticipated flux fall off is employed where averaging is not appropriate. A second estimator successfully uses a simple rejection technique in conjunction with detailed tracking where averaging isn`t needed. Test results show good agreement with known numeric solutions. Efficiencies are examined as a function of input parameter selection and problem difficulty.
Martz, R.L.; Gast, R.C.; Tyburski, L.J.
Monte Carlo Simulation of the Conversion X-Rays from the Electron Beam of PFMA-3
PFMA-3, a dense Plasma Focus device, is being optimized as an X-ray generator. X-rays are obtained from the conversion of the electron beam emitted in the backward direction and driven to impinge on a 50 {mu}m brass foil. Monte Carlo simulations of the X-ray emission have been conducted with MCNPX. The electron spectrum had been determined experimentally and is used in the present work as input to the simulations. Dose to the brass foil has been determined both from simulations and from measurements with a thermographic camera, and the two results are found in excellent agreement, thus validating further the electron spectrum assumed as well as the simulation set-up. X-ray emission has been predicted both from bremsstrahlung and from characteristic lines. The spectrum has been found to be comprised of two components of which the one at higher energy, 30 divide 70 keV, is most useful for IORT applications. The results are necessary to estimate penetration in and dose to Standard Human Tissue.
Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)
A Monte Carlo Analysis of Gas Centrifuge Enrichment Plant Process Load Cell Data
As uranium enrichment plants increase in number, capacity, and types of separative technology deployed (e.g., gas centrifuge, laser, etc.), more automated safeguards measures are needed to enable the IAEA to maintain safeguards effectiveness in a fiscally constrained environment. Monitoring load cell data can significantly increase the IAEA s ability to efficiently achieve the fundamental safeguards objective of confirming operations as declared (i.e., no undeclared activities), but care must be taken to fully protect the operator s proprietary and classified information related to operations. Staff at ORNL, LANL, JRC/ISPRA, and University of Glasgow are investigating monitoring the process load cells at feed and withdrawal (F/W) stations to improve international safeguards at enrichment plants. A key question that must be resolved is what is the necessary frequency of recording data from the process F/W stations? Several studies have analyzed data collected at a fixed frequency. This paper contributes to load cell process monitoring research by presenting an analysis of Monte Carlo simulations to determine the expected errors caused by low frequency sampling and its impact on material balance calculations.
Garner, James R [ORNL; Whitaker, J Michael [ORNL
Towards a frequency-dependent discrete maximum principle for the implicit Monte Carlo equations
It has long been known that temperature solutions of the Implicit Monte Carlo (IMC) equations can exceed the external boundary temperatures, a so-called violation of the 'maximum principle.' Previous attempts at prescribing a maximum value of the time-step size {Delta}{sub t} that is sufficient to eliminate these violations have recommended a {Delta}{sub t} that is typically too small to be used in practice and that appeared to be much too conservative when compared to numerical solutions of the IMC equations for practical problems. In this paper, we derive a new estimator for the maximum time-step size that includes the spatial-grid size {Delta}{sub x}. This explicitly demonstrates that the effect of coarsening {Delta}{sub x} is to reduce the limitation on {Delta}{sub t}, which helps explain the overly conservative nature of the earlier, grid-independent results. We demonstrate that our new time-step restriction is a much more accurate means of predicting violations of the maximum principle. We discuss how the implications of the new, grid-dependent timestep restriction can impact IMC solution algorithms.
Wollaber, Allan B [Los Alamos National Laboratory; Larsen, Edward W [Los Alamos National Laboratory; Densmore, Jeffery D [Los Alamos National Laboratory
Postimplant Dosimetry Using a Monte Carlo Dose Calculation Engine: A New Clinical Standard
Purpose: To use the Monte Carlo (MC) method as a dose calculation engine for postimplant dosimetry. To compare the results with clinically approved data for a sample of 28 patients. Two effects not taken into account by the clinical calculation, interseed attenuation and tissue composition, are being specifically investigated. Methods and Materials: An automated MC program was developed. The dose distributions were calculated for the target volume and organs at risk (OAR) for 28 patients. Additional MC techniques were developed to focus specifically on the interseed attenuation and tissue effects. Results: For the clinical target volume (CTV) D{sub 90} parameter, the mean difference between the clinical technique and the complete MC method is 10.7 Gy, with cases reaching up to 17 Gy. For all cases, the clinical technique overestimates the deposited dose in the CTV. This overestimation is mainly from a combination of two effects: the interseed attenuation (average, 6.8 Gy) and tissue composition (average, 4.1 Gy). The deposited dose in the OARs is also overestimated in the clinical calculation. Conclusions: The clinical technique systematically overestimates the deposited dose in the prostate and in the OARs. To reduce this systematic inaccuracy, the MC method should be considered in establishing a new standard for clinical postimplant dosimetry and dose-outcome studies in a near future.
Carrier, Jean-Francois [Departement de Radio-Oncologie, et Centre de Recherche du CHUM, Hopital Notre-Dame du CHUM, Montreal, Quebec (Canada) and Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de Universite Laval, CHUQ Pavillon Hotel-Dieu de Quebec, Quebec (Canada)]. E-mail: firstname.lastname@example.com; D' Amours, Michel [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de Universite Laval, CHUQ Pavillon Hotel-Dieu de Quebec, Quebec (Canada); Verhaegen, Frank [Medical Physics Unit, McGill University, Montreal, Quebec (Canada); Reniers, Brigitte [Medical Physics Unit, McGill University, Montreal, Quebec (Canada); Martin, Andre-Guy [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de Universite Laval, CHUQ Pavillon Hotel-Dieu de Quebec, Quebec (Canada); Vigneault, Eric [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de Universite Laval, CHUQ Pavillon Hotel-Dieu de Quebec, Quebec (Canada); Beaulieu, Luc [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie de Universite Laval, CHUQ Pavillon Hotel-Dieu de Quebec, Quebec (Canada)
We studied the decoupling of photons from ultra-relativistic spherically symmetric outflows expanding with constant velocity by means of Monte Carlo simulations. For outflows with finite widths we confirm the existence of two regimes: photon-thick and photon-thin, introduced recently by Ruffini et al. (RSV). The probability density function of the last scattering of photons is shown to be very different in these two cases. We also obtained spectra as well as light curves. In the photon-thick case, the time-integrated spectrum is much broader than the Planck function and its shape is well described by the fuzzy photosphere approximation introduced by RSV. In the photon-thin case, we confirm the crucial role of photon diffusion, hence the probability density of decoupling has a maximum near the diffusion radius well below the photosphere. The time-integrated spectrum of the photon-thin case has a Band shape that is produced when the outflow is optically thick and its peak is formed at the diffusion radius.
Begue, D.; Siutsou, I. A.; Vereshchagin, G. V. [University of Roma ''Sapienza'', I-00185, p.le A. Moro 5, Rome (Italy)
Monte Carlo analysis of a monolithic interconnected module with a back surface reflector
Recently, the photon Monte Carlo code, RACER-X, was modified to include wave-length dependent absorption coefficients and indices of refraction. This work was done in an effort to increase the code`s capabilities to be more applicable to a wider range of problems. These new features make RACER-X useful for analyzing devices like monolithic interconnected modules (MIMs) which have etched surface features and incorporates a back surface reflector (BSR) for spectral control. A series of calculations were performed on various MIM structures to determine the impact that surface features and component reflectivities have on spectral utilization. The traditional concern of cavity photonics is replaced with intra-cell photonics in the MIM design. Like the cavity photonic problems previously discussed, small changes in optical properties and/or geometry can lead to large changes in spectral utilization. The calculations show that seemingly innocuous surface features (e.g., trenches and grid lines) can significantly reduce the spectral utilization due to the non-normal incident photon flux. Photons that enter the device through a trench edge are refracted onto a trajectory where they will not escape. This leads to a reduction in the number of reflected below bandgap photons that return to the radiator and reduce the spectral utilization. In addition, trenches expose a lateral conduction layer in this particular series of calculations which increase the absorption of above bandgap photons in inactive material.
Ballinger, C.T.; Charache, G.W. [Lockheed Martin Corp., Schenectady, NY (United States); Murray, C.S. [Bettis Atomic Power Lab., West Mifflin, PA (United States)
We present a parameter estimation procedure based on a Bayesian framework by applying a Markov Chain Monte Carlo algorithm to the calibration of the dynamical parameters of a space based gravitational wave detector. The method is based on the Metropolis-Hastings algorithm and a two-stage annealing treatment in order to ensure an effective exploration of the parameter space at the beginning of the chain. We compare two versions of the algorithm with an application to a LISA Pathfinder data analysis problem. The two algorithms share the same heating strategy but with one moving in coordinate directions using proposals from a multivariate Gaussian distribution, while the other uses the natural logarithm of some parameters and proposes jumps in the eigen-space of the Fisher Information matrix. The algorithm proposing jumps in the eigen-space of the Fisher Information matrix demonstrates a higher acceptance rate and a slightly better convergence towards the equilibrium parameter distributions in the application to LISA Pathfinder data . For this experiment, we return parameter values that are all within $\\sim1\\sigma$ of the injected values. When we analyse the accuracy of our parameter estimation in terms of the effect they have on the force-per-unit test mass noise estimate, we find that the induced errors are three orders of magnitude less than the expected experimental uncertainty in the power spectral density.
Luigi Ferraioli; Edward K. Porter; Eric Plagnol
A BAYESIAN MONTE CARLO ANALYSIS OF THE M-{sigma} RELATION
We present an analysis of selection biases in the M{sub bh}-{sigma} relation using Monte Carlo simulations including the sphere of influence resolution selection bias and a selection bias in the velocity dispersion distribution. We find that the sphere of influence selection bias has a significant effect on the measured slope of the M{sub bh}-{sigma} relation, modeled as {beta}{sub intrinsic} = -4.69 + 2.22{beta}{sub measured}, where the measured slope is shallower than the model slope in the parameter range of {beta} > 4, with larger corrections for steeper model slopes. Therefore, when the sphere of influence is used as a criterion to exclude unreliable measurements, it also introduces a selection bias that needs to be modeled to restore the intrinsic slope of the relation. We find that the selection effect due to the velocity dispersion distribution of the sample, which might not follow the overall distribution of the population, is not important for slopes of {beta} {approx} 4-6 of a logarithmically linear M{sub bh}-{sigma} relation, which could impact some studies that measure low (e.g., {beta} < 4) slopes. Combining the selection biases in velocity dispersions and the sphere of influence cut, we find that the uncertainty of the slope is larger than the value without modeling these effects and estimate an intrinsic slope of {beta} = 5.28{sup +0.84}{sub -0.55}.
Morabito, Leah K.; Dai Xinyu, E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)
Monte Carlo Assessments of Absorbed Doses to the Hands of Radiopharmaceutical Workers Due to Photon Emitters
This paper describes the characterization of radiation doses to the hands of nuclear medicine technicians resulting from the handling of radiopharmaceuticals. Radiation monitoring using ring dosimeters indicates that finger dosimeters that are used to show compliance with applicable regulations may overestimate or underestimate radiation doses to the skin depending on the nature of the particular procedure and the radionuclide being handled. To better understand the parameters governing the absorbed dose distributions, a detailed model of the hands was created and used in Monte Carlo simulations of selected nuclear medicine procedures. Simulations of realistic configurations typical for workers handling radiopharmaceuticals were performedfor a range of energies of the source photons. The lack of charged-particle equilibrium necessitated full photon-electron coupled transport calculations. The results show that the dose to different regions of the fingers can differ substantially from dosimeter readings when dosimeters are located at the base of the finger. We tried to identify consistent patterns that relate the actual dose to the dosimeter readings. These patterns depend on the specific work conditions and can be used to better assess the absorbed dose to different regions of the exposed skin.
Ilas, Dan [ORNL; Eckerman, Keith F [ORNL; Karagiannis, Harriet [ORNL
A spherical Monte-Carlo model of aerosols: Validation and first applications to Mars and Titan
The atmospheres of Mars and Titan are loaded with aerosols that impact remote sensing observations of their surface. Here we present the algorithm and the first applications of a radiative transfer model in spherical geometry designed for planetary data analysis. We first describe a fast Monte-Carlo code that takes advantage of symmetries and geometric redundancies. We then apply this model to observations of the surface of Mars and Titan at the terminator as acquired by OMEGA/Mars Express and VIMS/Cassini. These observations are used to probe the vertical distribution of aerosols down to the surface. On Mars, we find the scale height of dust particles to vary between 6 km and 12 km depending on season. Temporal variations in the vertical size distribution of aerosols are also highlighted. On Titan, an aerosols scale height of 80 \\pm 10 km is inferred, and the total optical depth is found to decrease with wavelength as a power-law with an exponent of -2.0 \\pm 0.4 from a value of 2.3 \\pm 0.5 at 1.08 {\\mu}m. On...
Vincendon, Mathieu; 10.1016/j.icarus.2009.12.018
Electron energy and charge albedos - calorimetric measurement vs Monte Carlo theory
A new calorimetric method has been employed to obtain saturated electron energy albedos for Be, C, Al, Ti, Mo, Ta, U, and UO/sub 2/ over the range of incident energies from 0.1 to 1.0 MeV. The technique was so designed to permit the simultaneous measurement of saturated charge albedos. In the cases of C, Al, Ta, and U the measurements were extended down to about 0.025 MeV. The angle of incidence was varied from 0/sup 0/ (normal) to 75/sup 0/ in steps of 15/sup 0/, with selected measurements at 82.5/sup 0/ in Be and C. In each case, state-of-the-art predictions were obtained from a Monte Carlo model. The generally good agreement between theory and experiment over this extensive parameter space represents a strong validation of both the theoretical model and the new experimental method. Nevertheless, certain discrepancies at low incident energies, especially in high-atomic-number materials, and at all energies in the case of the U energy albedos are not completely understood.
Lockwood, G.J.; Ruggles, L.E.; Miller, G.H.; Halbleib, J.A.
Composition PDF/photon Monte Carlo modeling of moderately sooting turbulent jet flames
A comprehensive model for luminous turbulent flames is presented. The model features detailed chemistry, radiation and soot models and state-of-the-art closures for turbulence-chemistry interactions and turbulence-radiation interactions. A transported probability density function (PDF) method is used to capture the effects of turbulent fluctuations in composition and temperature. The PDF method is extended to include soot formation. Spectral gas and soot radiation is modeled using a (particle-based) photon Monte Carlo method coupled with the PDF method, thereby capturing both emission and absorption turbulence-radiation interactions. An important element of this work is that the gas-phase chemistry and soot models that have been thoroughly validated across a wide range of laminar flames are used in turbulent flame simulations without modification. Six turbulent jet flames are simulated with Reynolds numbers varying from 6700 to 15,000, two fuel types (pure ethylene, 90% methane-10% ethylene blend) and different oxygen concentrations in the oxidizer stream (from 21% O{sub 2} to 55% O{sub 2}). All simulations are carried out with a single set of physical and numerical parameters (model constants). Uniformly good agreement between measured and computed mean temperatures, mean soot volume fractions and (where available) radiative fluxes is found across all flames. This demonstrates that with the combination of a systematic approach and state-of-the-art physical models and numerical algorithms, it is possible to simulate a broad range of luminous turbulent flames with a single model. (author)
Mehta, R.S.; Haworth, D.C.; Modest, M.F. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)
A novel Monte Carlo algorithm for polarizable force fields: Application to a fluctuating charge model for water
In this Monte Carlo algorithm for polarizable force fields, the fluctuating charges are treated as special degrees of freedom subject to a secondary low-temperature thermostat in close analogy to the extended Lagrangian formalism commonly used in molecular dynamics simulations of such systems. The algorithm is applied to Berne{close_quote}s SPC-FQ (simple point charge{endash}fluctuating charge) model for water. The robustness of the algorithm with respect to the temperature of the secondary thermostat and to the fraction of fluctuating-charge moves is investigated. With the new algorithm, the cost of Monte Carlo simulations using fluctuating-charge force fields increases by less than an order of magnitude compared to simulations using the parent fixed-charge force fields. {copyright} {ital 1998 American Institute of Physics.}
Martin, M.G.; Chen, B.; Siepmann, J.I. [Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455-0431 (United States)
Sensitivity analysis of reactivity responses using one-dimensional discrete ordinates and three-dimensional Monte Carlo methods
The TSUNAMI computational sequences currently in the SCALE 5 code system provide an automated approach to performing sensitivity and uncertainty analysis for eigenvalue responses, using either one-dimensional discrete ordinates or three-dimensional Monte Carlo methods. This capability has recently been expanded to address eigenvalue-difference responses such as reactivity changes. This paper describes the methodology and presents results obtained for an example advanced CANDU reactor design. (authors)
Williams, M. L.; Gehin, J. C.; Clarno, K. T. [Oak Ridge National Laboratory, Bldg. 5700, P.O. Box 2008, Oak Ridge, TN 37831-6170 (United States)
Multi-potential interactions in plasma adopting a GPU version of the reaction ensemble Monte Carlo method
Calculations of thermodynamic properties of Helium plasma by using the Reaction Ensemble Monte Carlo method (REMC) are presented. Non ideal effects at high pressure are observed. Calculations, performed by using Exp-6 or multi-potential curves in the case of neutral-charge interactions, show that in the thermodynamic conditions considered no significative differences are observed. Results have been obtained by using a Graphics Processing Unit (GPU)-CUDA C version of REMC.
D'Angola, A.; Tuttafesta, M.; Guadagno, M.; Santangelo, P.; Laricchiuta, A.; Colonna, G.; Capitelli, M. [Scuola di Ingegneria SI, Universita della Basilicata, via dell'Ateneo Lucano, 10 - 85100 Potenza (Italy); Universita di Bari, via Orabona, 4 - 70126 Bari (Italy); Scuola di Ingegneria SI, Universita della Basilicata, via dell'Ateneo Lucano, 10 - 85100 Potenza (Italy); CNR-IMIP Bari, via Amendola 122/D - 70126 Bari (Italy); Universita di Bari, via Orabona, 4 - 70126 Bari (Italy) and CNR-IMIP Bari, via Amendola 122/D - 70126 Bari (Italy)
FPGA acceleration using high-level languages of a Monte-Carlo method for pricing complex options
In this paper we present an FPGA implementation of a Monte-Carlo method for pricing Asian options using Impulse C and floating-point arithmetic. In an Altera Stratix-V FPGA, a 149x speedup factor was obtained against an OpenMP-based solution in a 4-core ... Keywords: Field programmable gate arrays, Financial data processing, Floating-point arithmetic, High level language synthesis, Parallel machines
Diego Sanchez-Roman, Victor Moreno, Sergio Lopez-Buedo, Gustavo Sutter, Ivan Gonzalez, Francisco J. Gomez-Arribas, Javier Aracil
Study of the validity of a combined potential model using the hybrid reverse Monte Carlo method in fluoride glass system
The choice of appropriate interaction models is among the major disadvantages of conventional methods such as molecular dynamics and Monte Carlo simulations. On the other hand, the so-called reverse Monte Carlo (RMC) method, based on experimental data, can be applied without any interatomic and/or intermolecular interactions. The RMC results are accompanied by artificial satellite peaks. To remedy this problem, we use an extension of the RMC algorithm, which introduces an energy penalty term into the acceptance criteria. This method is referred to as the hybrid reverse Monte Carlo (HRMC) method. The idea of this paper is to test the validity of a combined potential model of coulomb and Lennard-Jones in a fluoride glass system BaMnMF_{7} (M=Fe,V) using HRMC method. The results show a good agreement between experimental and calculated characteristics, as well as a meaningful improvement in partial pair distribution functions. We suggest that this model should be used in calculating the structural properties and in describing the average correlations between components of fluoride glass or a similar system. We also suggest that HRMC could be useful as a tool for testing the interaction potential models, as well as for conventional applications.
S. M. Mesli; M. Habchi; M. Kotbi; H. Xu
N-(sulfoethyl) iminodiacetic acid-based lanthanide coordination polymers: Synthesis, magnetism and quantum Monte Carlo studies
A series of lanthanide coordination polymers have been obtained through the hydrothermal reaction of N-(sulfoethyl) iminodiacetic acid (H{sub 3}SIDA) and Ln(NO{sub 3}){sub 3} (Ln=La, 1; Pr, 2; Nd, 3; Gd, 4). Crystal structure analysis exhibits that lanthanide ions affect the coordination number, bond length and dimension of compounds 1-4, which reveal that their structure diversity can be attributed to the effect of lanthanide contraction. Furthermore, the combination of magnetic measure with quantum Monte Carlo(QMC) studies exhibits that the coupling parameters between two adjacent Gd{sup 3+} ions for anti-anti and syn-anti carboxylate bridges are -1.0 Multiplication-Sign 10{sup -3} and -5.0 Multiplication-Sign 10{sup -3} cm{sup -1}, respectively, which reveals weak antiferromagnetic interaction in 4. - Graphical abstract: Four lanthanide coordination polymers with N-(sulfoethyl) iminodiacetic acid were obtained under hydrothermal condition and reveal the weak antiferromagnetic coupling between two Gd{sup 3+} ions by Quantum Monte Carlo studies. Highlights: Black-Right-Pointing-Pointer Four lanthanide coordination polymers of H{sub 3}SIDA ligand were obtained. Black-Right-Pointing-Pointer Lanthanide ions play an important role in their structural diversity. Black-Right-Pointing-Pointer Magnetic measure exhibits that compound 4 features antiferromagnetic property. Black-Right-Pointing-Pointer Quantum Monte Carlo studies reveal the coupling parameters of two Gd{sup 3+} ions.
Zhuang Guilin, E-mail: email@example.com [Institute of Industrial Catalysis, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Chen Wulin [Institute of Industrial Catalysis, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Zheng Jun [Center of Modern Experimental Technology, Anhui University, Hefei 230039 (China); Yu Huiyou [Institute of Industrial Catalysis, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Wang Jianguo, E-mail: email@example.com [Institute of Industrial Catalysis, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)
A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra
A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO{sub 2} in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.
Da, B.; Sun, Y.; Ding, Z. J. [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People's Republic of China (China)] [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People's Republic of China (China); Mao, S. F. [School of Nuclear Science and Technology, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People's Republic of China (China)] [School of Nuclear Science and Technology, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People's Republic of China (China); Zhang, Z. M. [Centre of Physical Experiments, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People's Republic of China (China)] [Centre of Physical Experiments, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People's Republic of China (China); Jin, H.; Yoshikawa, H.; Tanuma, S. [Advanced Surface Chemical Analysis Group, National Institute for Materials Science, 1-2-1 Sengen Tsukuba, Ibaraki 305-0047 (Japan)] [Advanced Surface Chemical Analysis Group, National Institute for Materials Science, 1-2-1 Sengen Tsukuba, Ibaraki 305-0047 (Japan)
SU?E?T?21: A Grid Intensity?Based Dose Algorithm to Realize MLC Irregular and Inhomogeneous Field Modeling for Monte Carlo Clinical Application
Purpose: A grid intensity?based dose algorithm to realize MLC irregular?inhomogeneous field modeling is presented for Monte Carlo clinical application in ARTS (Accurate Radiotherapy System). Methods: Linac modeling actually is a multi?parameter optimization process
Point-defect optical transitions and thermal ionization energies from quantum Monte Carlo methods: Application to the F-center defect in MgO
We present an approach to calculation of point-defect optical and thermal ionization energies based on the highly accurate quantum Monte Carlo methods. The use of an inherently many-body theory that directly treats electron ...
Ertekin, Elif
Organ doses for reference pediatric and adolescent patients undergoing computed tomography estimated by Monte Carlo simulation
Purpose: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model. Methods: The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs/tissues normalized to the product of 100 mAs and CTDI{sub vol} (mGy/100 mAs mGy) was established by coupling the CT scanner model with age-dependent reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI{sub vol}- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP). Results: Organ and effective doses were calculated and normalized to 100 mAs and CTDI{sub vol} for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and/or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose differences up to several-fold when organs were partially included in the scan coverage. Second, selected organ doses from our calculations agreed to within 20% of values derived from empirical formulae based upon measured patient abdominal circumference. Third, the existing DLP-to-effective dose conversion coefficients tended to be smaller than values given in the present study for all examinations except head scans. Conclusions: A comprehensive organ/effective dose database was established to readily calculate doses for given patients undergoing different CT examinations. The comparisons of our results with the existing studies highlight that use of hybrid phantoms with realistic anatomy is important to improve the accuracy of CT organ dosimetry. The comprehensive pediatric dose data developed here are the first organ-specific pediatric CT scan database based on the realistic pediatric hybrid phantoms which are compliant with the reference data from the International Commission on Radiological Protection (ICRP). The organ dose database is being coupled with an adult organ dose database recently published as part of the development of a user-friendly computer program enabling rapid estimates of organ and effective dose doses for patients of any age, gender, examination types, and CT scanner model.
Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.; Bolch, Wesley E. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear Engineering, Kyung Hee University, Gyeonggi-do, 446906 (Korea, Republic of); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States)
Simulation and Analysis of a Tissue Equivalent Proportional Counter Using the Monte Carlo Transport Code FLUKA
The purpose of this study was to determine how well the Monte Carlo transport
code FLUKA can simulate a tissue-equivalent proportional counter (TEPC) and produce
the expected delta ray events when exposed to high energy heavy ions (HZE) like in the
galactic cosmic ray (GCR) environment. Accurate transport codes are desirable because
of the high cost of beam time, the inability to measure the mixed field GCR on the
ground and the flexibility they offer in the engineering and design process.
A spherical TEPC simulating a 1 um site size was constructed in FLUKA and its
response was compared to experimental data for an 56Fe beam at 360 MeV/nucleon. The
response of several narrow beams at different impact parameters were used to explain
the features of the response of the same detector exposed to a uniform field of radiation.
Additionally, an investigation was made into the effect of the wall thickness on the
response of the TEPC and the range of delta rays in the tissue-equivalent (TE) wall
material. A full impact parameter test (from IP = 0 to IP = detector radius) was
performed to show that FLUKA produces the expected wall effect. That is, energy deposition in the gas volume can occur even when the primary beam does not pass
through the gas volume.
A final comparison to experimental data was made for the simulated TEPC
exposed to various broad beams in the energy range of 200 - 1000 MeV/nucleon.
FLUKA overestimated energy deposition in the gas volume in all cases. The FLUKA
results differed from the experimental data by an average of 25.2 % for yF and 12.4 %
for yD. It is suggested that this difference can be reduced by adjusting the FLUKA
default ionization potential and density correction factors.
Northum, Jeremy Dell
Understanding of Ethanol Decomposition on Rh(111) From Density Functional Theory and Kinetic Monte Carlo Simulations
Reaction mechanisms of ethanol decomposition on Rh(1 1 1) were elucidated by means of periodic density functional theory (DFT) calculations and kinetic Monte Carlo (KMC) simulations. We propose that the most probable reaction pathway is via CH{sub 3}CH{sub 2}O* on the basis of our mechanistic study: CH{sub 3}CH{sub 2}OH* {yields} CH{sub 3}CH{sub 2}O* {yields} CH{sub 2}CH{sub 2}O* {yields} CH{sub 2}CHO* {yields} CH{sub 2}CO* {yields} CHCO* {yields} CH* + CO* {yields} C* + CO*. In contrast, the contribution from the pathway via CH{sub 3}CHOH* is relatively small, CH{sub 3}CH{sub 2}OH* {yields} CH{sub 3}CHOH* {yields} CH{sub 3}CHO* {yields} CH{sub 3}CO* {yields} CH{sub 2}CO* {yields} CHCO* {yields} CH* + CO* {yields} C* + CO*. According to our calculations, one of the slow steps is the formation of the oxametallacycle CH{sub 2}CH{sub 2}O* species, which leads to the production of CHCO*, the precursor for C-C bond breaking. Finally, the decomposition of ethanol leads to the production of C and CO. Our calculations, for ethanol combustion on Rh, the major obstacle is not C-C bond cleavage, but the C contamination on Rh(1 1 1). The strong C-Rh interaction may deactivate the Rh catalyst. The formation of Rh alloys with Pt and Pd weakens the C-Rh interaction, easing the removal of C, and, as expected, in accordance with the experimental findings, facilitating ethanol combustion.
Liu, P.; Choi, Y.M.
Continuous reservoir simulation model updating and forecasting using a markov chain monte carlo method
Currently, effective reservoir management systems play a very important part in exploiting reservoirs. Fully exploiting all the possible events for a petroleum reservoir is a challenge because of the infinite combinations of reservoir parameters. There is much unknown about the underlying reservoir model, which has many uncertain parameters. MCMC (Markov Chain Monte Carlo) is a more statistically rigorous sampling method, with a stronger theoretical base than other methods. The performance of the MCMC method on a high dimensional problem is a timely topic in the statistics field. This thesis suggests a way to quantify uncertainty for high dimensional problems by using the MCMC sampling process under the Bayesian frame. Based on the improved method, this thesis reports a new approach in the use of the continuous MCMC method for automatic history matching. The assimilation of the data in a continuous process is done sequentially rather than simultaneously. In addition, by doing a continuous process, the MCMC method becomes more applicable for the industry. Long periods of time to run just one realization will no longer be a big problem during the sampling process. In addition, newly observed data will be considered once it is available, leading to a better estimate. The PUNQ-S3 reservoir model is used to test two methods in this thesis. The methods are: STATIC (traditional) SIMULATION PROCESS and CONTINUOUS SIMULATION PROCESS. The continuous process provides continuously updated probabilistic forecasts of well and reservoir performance, accessible at any time. It can be used to optimize long-term reservoir performance at field scale.
Liu, Chang
Buena Vista County, Virginia: Energy Resources | Open Energy Information
36934°, -79.352188° 36934°, -79.352188° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.7336934,"lon":-79.352188,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Lago Vista, Texas: Energy Resources | Open Energy Information
Texas: Energy Resources Texas: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 30.4601975°, -97.9883477° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":30.4601975,"lon":-97.9883477,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Buena Vista, Michigan: Energy Resources | Open Energy Information
Michigan: Energy Resources Michigan: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 43.4203028°, -83.8985827° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":43.4203028,"lon":-83.8985827,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Buena Vista County, Iowa: Energy Resources | Open Energy Information
05452°, -95.1432068° 05452°, -95.1432068° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":42.6705452,"lon":-95.1432068,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Vista Center, New Jersey: Energy Resources | Open Energy Information
New Jersey: Energy Resources New Jersey: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 40.1592798°, -74.3179248° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":40.1592798,"lon":-74.3179248,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Sierra Vista, Arizona: Energy Resources | Open Energy Information
5545394°, -110.3036912° 5545394°, -110.3036912° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":31.5545394,"lon":-110.3036912,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Vista West, Wyoming: Energy Resources | Open Energy Information
Wyoming: Energy Resources Wyoming: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 42.8599962°, -106.4346979° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":42.8599962,"lon":-106.4346979,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Sierra Vista Southeast, Arizona: Energy Resources | Open Energy Information
Southeast, Arizona: Energy Resources Southeast, Arizona: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 31.460592°, -110.217428° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":31.460592,"lon":-110.217428,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Vista Program Capabilities for Analysis of Biomass Co-Firing
The ever-increasing focus on greenhouse gas emissions reductions is of critical importance to coal-fired power plants, as they produce a large amount of the total anthropogenic CO2 emissions. One commonly considered method of reducing the net CO2 emissions of a coal-fired power plant is by burning renewable biomass to generate heat and power. Although biomass is the oldest combustible fuel, knowledge of the effects that co-firing biomass will have on a coal-fired boiler is sometimes lacking at power plan...
City of Alta Vista, Iowa (Utility Company) | Open Energy Information
Iowa Utility Id 432 Utility Location Yes Ownership M NERC Location MRO Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1a1 LinkedIn...
Employing the EPRI Vista Program for Test Burn Risk Assessment
The drive to use fuel switching as a means to meet more stringent SO2 and NOX emissions requirements has in many cases led to both a reduction in power station efficiency and a poorer net plant heat rate (NPHR) at the power station, as well as significant reductions in operating margins and increases in the risk of unit derates. One excellent method to manage or mitigate this risk is a comprehensive test burn for fuels under consideration. The objectives of this technical report are to demonstrate how th...
Pages that link to "Nordic Turbines Inc formerly Vista Dorada...
Policies International Clean Energy Analysis Low Emission Development Strategies Oil & Gas Smart Grid Solar U.S. OpenLabs Utilities Water Wind Page Actions View source History...
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Alta Vista: Simple Query "merde d'alors" - CECM
Tip: To use all these apples: +apple pie tart cookie torte muffin. Ignored: merde d alors:0. No documents match the query. The term does not appear in the index.
Chula Vista, Florida: Energy Resources | Open Energy Information
02262°, -80.1833217° 02262°, -80.1833217° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":26.1002262,"lon":-80.1833217,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
A novel approach in electron beam radiation therapy of lips carcinoma: A Monte Carlo study
Purpose: Squamous cell carcinoma (SCC) is commonly treated by electron beam radiotherapy (EBRT) followed by a boost via brachytherapy. Considering the limitations associated with brachytherapy, in this study, a novel boosting technique in EBRT of lip carcinoma using an internal shield as an internal dose enhancer tool (IDET) was evaluated. An IDET is referred to a partially covered internal shield located behind the lip. It was intended to show that while the backscattered electrons are absorbed in the portion covered with a low atomic number material, they will enhance the target dose in the uncovered area. Methods: Monte-Carlo models of 6 and 8 MeV electron beams were developed using BEAMnrc code and were validated against experimental measurements. Using the developed models, dose distributions in a lip phantom were calculated and the effect of an IDET on target dose enhancement was evaluated. Typical lip thicknesses of 1.5 and 2.0 cm were considered. A 5 Multiplication-Sign 5 cm{sup 2} of lead covered by 0.5 cm of polystyrene was used as an internal shield, while a 4 Multiplication-Sign 4 cm{sup 2} uncovered area of the shield was used as the dose enhancer. Results: Using the IDET, the maximum dose enhancement as a percentage of dose at d{sub max} of the unshielded field was 157.6% and 136.1% for 6 and 8 MeV beams, respectively. The best outcome was achieved for lip thickness of 1.5 cm and target thickness of less than 0.8 cm. For lateral dose coverage of planning target volume, the 80% isodose curve at the lip-IDET interface showed a 1.2 cm expansion, compared to the unshielded field. Conclusions: This study showed that a boost concomitant EBRT of lip is possible by modifying an internal shield into an IDET. This boosting method is especially applicable to cases in which brachytherapy faces limitations, such as small thicknesses of lips and targets located at the buccal surface of the lip.
Shokrani, Parvaneh [Medical Physics and Medical Engineering Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Baradaran-Ghahfarokhi, Milad [Medical Physics and Medical Engineering Department, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran and Medical Radiation Engineering Department, Faculty of Advanced Sciences and Technologies, Isfahan University, Isfahan 81746-73441 (Iran, Islamic Republic of); Zadeh, Maryam Khorami [Medical Physics Department, School of Medicine, Ahwaz Jundishapour University of Medical Sciences, Ahwaz 15794-61357 (Iran, Islamic Republic of)
Monte Carlo simulations of electron thermalization in alkali iodide and alkaline-earth fluoride scintillators
A Monte Carlo model of electron thermalization in inorganic scintillators, which was developed and applied to CsI in a previous publication [Wang et al., J. Appl. Phys. 110, 064903 (2011)], is extended to another material of the alkali halide class, NaI, and to two materials from the alkaline-earth halide class, CaF2 and BaF2. This model includes electron scattering with both longitudinal optical (LO) and acoustic phonons as well as the effects of internal electric fields. For the four pure materials, a significant fraction of the electrons recombine with self-trapped holes and the thermalization distance distributions of the electrons that do not recombine peak between approximately 25 and 50 {per_thousand}nm and extend up to a few hundreds of nanometers. The thermalization time distributions of CaF2, BaF2, NaI, and CsI extend to approximately 0.5, 1, 2, and 7 ps, respectively. The simulations show that the LO phonon energy is a key factor that affects the electron thermalization process. Indeed, the higher the LO phonon energy is, the shorter the thermalization time and distance are. The thermalization time and distance distributions show no dependence on the incident {gamma}-ray energy. The four materials also show different extents of electron-hole pair recombination due mostly to differences in their electron mean free paths (MFPs), LO phonon energies, initial densities of electron-hole pairs, and static dielectric constants. The effect of thallium doping is also investigated for CsI and NaI as these materials are often doped with activators. Comparison between CsI and NaI shows that both the larger size of Cs+ relative to Na+, i.e., the greater atomic density of NaI, and the longer electron mean free path in NaI compared to CsI contribute to an increased probability for electron trapping at Tl sites in NaI versus CsI.
Wang, Zhiguo; Xie, YuLong; Campbell, Luke W.; Gao, Fei; Kerisit, Sebastien N.
A Monte Carlo model of electron thermalization in inorganic scintillators, which was developed and applied to CsI in a previous publication [Wang et al., J. Appl. Phys. 110, 064903 (2011)], is extended to another material of the alkali halide class, NaI, and to two materials from the alkaline-earth halide class, CaF{sub 2} and BaF{sub 2}. This model includes electron scattering with both longitudinal optical (LO) and acoustic phonons as well as the effects of internal electric fields. For the four pure materials, a significant fraction of the electrons recombine with self-trapped holes and the thermalization distance distributions of the electrons that do not recombine peak between approximately 25 and 50 nm and extend up to a few hundreds of nanometers. The thermalization time distributions of CaF{sub 2}, BaF{sub 2}, NaI, and CsI extend to approximately 0.5, 1, 2, and 7 ps, respectively. The simulations show that the LO phonon energy is a key factor that affects the electron thermalization process. Indeed, the higher the LO phonon energy is, the shorter the thermalization time and distance are. The thermalization time and distance distributions show no dependence on the incident {gamma}-ray energy. The four materials also show different extents of electron-hole pair recombination due mostly to differences in their electron mean free paths (MFPs), LO phonon energies, initial densities of electron-hole pairs, and static dielectric constants. The effect of thallium doping is also investigated for CsI and NaI as these materials are often doped with activators. Comparison between CsI and NaI shows that both the larger size of Cs{sup +} relative to Na{sup +}, i.e., the greater atomic density of NaI, and the longer electron mean free path in NaI compared to CsI contribute to an increased probability for electron trapping at Tl sites in NaI versus CsI.
Wang Zhiguo; Gao Fei; Kerisit, Sebastien [Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Xie Yulong [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Campbell, Luke W. [National Security Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
Monte Carlo simulation of the effect of miniphantom on in-air output ratio
Purpose: The aim of the study was to quantify the effect of miniphantoms on in-air output ratio measurements, i.e., to determine correction factors for in-air output ratio. Methods: Monte Carlo (MC) simulations were performed to simulate in-air output ratio measurements by using miniphantoms made of various materials (PMMA, graphite, copper, brass, and lead) and with different longitudinal thicknesses or depths (2-30 g/cm{sup 2}) in photon beams of 6 and 15 MV, respectively, and with collimator settings ranging from 3x3 to 40x40 cm{sup 2}. EGSnrc and BEAMnrc (2007) software packages were used. Photon energy spectra corresponding to the collimator settings were obtained from BEAMnrc code simulations on a linear accelerator and were used to quantify the components of in-air output ratio correction factors, i.e., attenuation, mass energy absorption, and phantom scatter correction factors. In-air output ratio correction factors as functions of miniphantom material, miniphantom longitudinal thickness, and collimator setting were calculated and compared to a previous experimental study. Results: The in-air output ratio correction factors increase with collimator opening and miniphantom longitudinal thickness for all the materials and for both energies. At small longitudinal thicknesses, the in-air output ratio correction factors for PMMA and graphite are close to 1. The maximum magnitudes of the in-air output ratio correction factors occur at the largest collimator setting (40x40 cm{sup 2}) and the largest miniphantom longitudinal thickness (30 g/cm{sup 2}): 1.008{+-}0.001 for 6 MV and 1.012{+-}0.001 for 15 MV, respectively. The MC simulations of the in-air output ratio correction factor confirm the previous experimental study. Conclusions: The study has verified that a correction factor for in-air output ratio can be obtained as a product of attenuation correction factor, mass energy absorption correction factor, and phantom scatter correction factor. The correction factors obtained in the present study can be used in studies involving in-air output ratio measurements using miniphantoms.
Li Jun; Zhu, Timothy C. [Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 (United States); Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)
Creation of a GUI for Zori, a Quantum Monte Carlo program, usingRappture
In their research laboratories, academic institutions produce some of the most advanced software for scientific applications. However, this software is usually developed only for local application in the research laboratory or for method development. In spite of having the latest advances in the particular field of science, such software often lacks adequate documentation and therefore is difficult to use by anyone other than the code developers. As such codes become more complex, so typically do the input files and command statements necessary to operate them. Many programs offer the flexibility of performing calculations based on different methods that have their own set of variables and options to be specified. Moreover, situations can arise in which certain options are incompatible with each other. For this reason, users outside the development group can be unaware of how the program runs in detail. The opportunity can be lost to make the software readily available outside of the laboratory of origin. This is a long-standing problem in scientific programming. Rappture, Rapid Application Infrastructure [1], is a new GUI development kit that enables a developer to build an I/O interface for a specific application. This capability enables users to work only with the generated GUI and avoids the problem of the user needing to learn details of the code. Further, it reduces input errors by explicitly specifying the variables required. Zori, a quantum Monte Carlo (QMC) program, developed by the Lester group at the University of California, Berkeley [2], is one of the few free tools available for this field. Like many scientific computer packages, Zori suffers from the problems described above. Potential users outside the research group have acquired it, but some have found the code difficult to use. Furthermore, new members of the Lester group usually have to take considerable time learning all the options the code has to offer before they can use it successfully. In this paper we describe the use of the Rappture toolkit to generate a GUI, labeled Zopi (Zori Processing Interface), for the Zori computer code.
Olivares-Amaya, R.; Salomon Ferrer, R.; Lester Jr., W.A.; Amador-Bedolla, C.
Relative Damaging Ability Of Galactic Cosmic Rays Determined Using Monte Carlo Simulations Of Track Structure
The energy deposition characteristics of heavy ions vary substantially compared to those of photons. Many radiation biology studies have compared the damaging effects of different types of radiation to establish relative biological effectiveness among them. These studies are dependent on cell type, biological endpoint, radiation type, dose, and dose rate. The radiation field found in space is much more complicated than that simulated in most experiments, both from a point of dose-rate as well as the highly mixed field of radiative particles encompassing a broad spectrum of energies. To establish better estimates for radiation risks on long-term, deep space missions, the damaging ability of heavy ions requires further understanding. Track structure studies provide significant details about the spatial distribution of energy deposition events in and around the sensitive targets of a mammalian cell. The damage imparted by one heavy ion relative to another can be established by modeling the track structures of ions that make up the galactic cosmic ray (GCR) spectrum and emphasizing biologically relevant target geometries. This research was undertaken to provide a better understanding of the damaging ability of GCR at the cellular level. By comparing ions with equal stopping power values, the differences in track structure will illuminate variations in cell particle traversals and ionization density within cell nuclei. For a cellular target, increased particle traversals, along with increased ionization density, are key identifiers for increased damaging ability. Performing Monte Carlo simulations with the computer code, FLUKA, this research will provide cellular dosimetry data and detail the track structure of the ions. As shown in radiobiology studies, increased ionizations within a cell nucleus generally lead to increased DNA breaks and increased free radical production, resulting in increased carcinogenesis and cell death. The spatial distribution of dose surrounding ions tracks are compared for inter- and intracellular regions. A comparison can be made for many different ions based upon dose and particle fluence across those different regions to predict relative damaging ability. This information can be used to improve estimates for radiation quality and dose equivalent from the space radiation environment.
Cox, Bradley
Monte Carlo methods of neutron beam design for neutron capture therapy at the MIT Research Reactor (MITR-II)
Monte Carlo methods of coupled neutron/photon transport are being used in the design of filtered beams for Neutron Capture Therapy (NCT). This method of beam analysis provides segregation of each individual dose component, and thereby facilitates beam optimization. The Monte Carlo method is discussed in some detail in relation to NCT epithermal beam design. Ideal neutron beams (i.e., plane-wave monoenergetic neutron beams with no primary gamma-ray contamination) have been modeled both for comparison and to establish target conditions for a practical NCT epithermal beam design. Detailed models of the 5 MWt Massachusetts Institute of Technology Research Reactor (MITR-II) together with a polyethylene head phantom have been used to characterize approximately 100 beam filter and moderator configurations. Using the Monte Carlo methodology of beam design and benchmarking/calibrating our computations with measurements, has resulted in an epithermal beam design which is useful for therapy of deep-seated brain tumors. This beam is predicted to be capable of delivering a dose of 2000 RBE-cGy (cJ/kg) to a therapeutic advantage depth of 5.7 cm in polyethylene assuming 30 micrograms/g 10B in tumor with a ten-to-one tumor-to-blood ratio, and a beam diameter of 18.4 cm. The advantage ratio (AR) is predicted to be 2.2 with a total irradiation time of approximately 80 minutes. Further optimization work on the MITR-II epithermal beams is expected to improve the available beams. 20 references.
Clement, S.D.; Choi, J.R.; Zamenhof, R.G.; Yanch, J.C.; Harling, O.K. (Massachusetts Institute of Technology, Cambridge (USA))
A user`s manual for MASH 1.0: A Monte Carlo Adjoint Shielding Code System
The Monte Carlo Adjoint Shielding Code System, MASH, calculates neutron and gamma-ray environments and radiation protection factors for armored military vehicles, structures, trenches, and other shielding configurations by coupling a forward discrete ordinates air-over-ground transport calculation with an adjoint Monte Carlo treatment of the shielding geometry. Efficiency and optimum use of computer time are emphasized. The code system include the GRTUNCL and DORT codes for air-over-ground transport calculations, the MORSE code with the GIFT5 combinatorial geometry package for adjoint shielding calculations, and several peripheral codes that perform the required data preparations, transformations, and coupling functions. MASH is the successor to the Vehicle Code System (VCS) initially developed at Oak Ridge National Laboratory (ORNL). The discrete ordinates calculation determines the fluence on a coupling surface surrounding the shielding geometry due to an external neutron/gamma-ray source. The Monte Carlo calculation determines the effectiveness of the fluence at that surface in causing a response in a detector within the shielding geometry, i.e., the ``dose importance`` of the coupling surface fluence. A coupling code folds the fluence together with the dose importance, giving the desired dose response. The coupling code can determine the dose response a a function of the shielding geometry orientation relative to the source, distance from the source, and energy response of the detector. This user`s manual includes a short description of each code, the input required to execute the code along with some helpful input data notes, and a representative sample problem (input data and selected output edits) for each code.
Johnson, J.O. [ed.
EchoSeed Model 6733 Iodine-125 brachytherapy source: Improved dosimetric characterization using the MCNP5 Monte Carlo code
This study primarily aimed to obtain the dosimetric characteristics of the Model 6733 {sup 125}I seed (EchoSeed) with improved precision and accuracy using a more up-to-date Monte-Carlo code and data (MCNP5) compared to previously published results, including an uncertainty analysis. Its secondary aim was to compare the results obtained using the MCNP5, MCNP4c2, and PTRAN codes for simulation of this low-energy photon-emitting source. The EchoSeed geometry and chemical compositions together with a published {sup 125}I spectrum were used to perform dosimetric characterization of this source as per the updated AAPM TG-43 protocol. These simulations were performed in liquid water material in order to obtain the clinically applicable dosimetric parameters for this source model. Dose rate constants in liquid water, derived from MCNP4c2 and MCNP5 simulations, were found to be 0.993 cGyh{sup -1} U{sup -1} ({+-}1.73%) and 0.965 cGyh{sup -1} U{sup -1} ({+-}1.68%), respectively. Overall, the MCNP5 derived radial dose and 2D anisotropy functions results were generally closer to the measured data (within {+-}4%) than MCNP4c and the published data for PTRAN code (Version 7.43), while the opposite was seen for dose rate constant. The generally improved MCNP5 Monte Carlo simulation may be attributed to a more recent and accurate cross-section library. However, some of the data points in the results obtained from the above-mentioned Monte Carlo codes showed no statistically significant differences. Derived dosimetric characteristics in liquid water are provided for clinical applications of this source model.
Mosleh-Shirazi, M. A.; Hadad, K.; Faghihi, R.; Baradaran-Ghahfarokhi, M.; Naghshnezhad, Z.; Meigooni, A. S. [Center for Research in Medical Physics and Biomedical Engineering and Physics Unit, Radiotherapy Department, Shiraz University of Medical Sciences, Shiraz 71936-13311 (Iran, Islamic Republic of); Radiation Research Center and Medical Radiation Department, School of Engineering, Shiraz University, Shiraz 71936-13311 (Iran, Islamic Republic of); Comprehensive Cancer Center of Nevada, Las Vegas, Nevada 89169 (United States)
Search for New Heavy Higgs Boson in B-L model at the LHC using Monte Carlo Simulation
The aim of this work is to search for a new heavy Higgs boson in the B-L extension of the Standard Model at LHC using the data produced from simulated collisions between two protons at different center of mass energies by Monte Carlo event generator programs to find new Higgs boson signatures at the LHC. Also we study the production and decay channels for Higgs boson in this model and its interactions with the other new particles of this model namely the new neutral gauge massive boson and the new fermionic right-handed heavy neutrinos .
Hesham Mansour; Nady Bakhet
Extrapolating Monte Carlo simulations to infinite volume: Finite-size scaling at {xi}/{ital L}{much_gt}1
We present a simple and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume, based on finite-size-scaling theory. We discuss carefully its systematic and statistical errors, and we illustrate it using three examples: the two-dimensional three-state Potts antiferromagnet on the square lattice, and the two-dimensional {ital O}(3) and {ital O}({infinity}) {sigma} models. In favorable cases it is possible to obtain reliable extrapolations (errors of a few percent) even when the correlation length is 1000 times larger than the lattice.
Caracciolo, S. [Dipartimento di Fisica, Universita di Lecce and INFN-Sezione di Lecce, I-73100 Lecce (Italy)] [Dipartimento di Fisica, Universita di Lecce and INFN-Sezione di Lecce, I-73100 Lecce (Italy); Edwards, R.G. [Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306 (United States)] [Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306 (United States); Ferreira, S.J. [Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, Minas Gerais 30161 (Brazil)] [Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, Minas Gerais 30161 (Brazil); Pelissetto, A.; Sokal, A.D. [Department of Physics, New York University, 4 Washington Place, New York, New York 10003 (United States)] [Department of Physics, New York University, 4 Washington Place, New York, New York 10003 (United States)
MonChER: Monte-Carlo generator for CHarge Exchange Reactions. Version 1.1. Physics and Manual
MonChER is a Monte Carlo event generator for simulation of single and double charge exchange reactions in proton-proton collisions at energies from 0.9 to 14 TeV. Such reactions, $pp\\to n+X$ and $pp\\to n+X+n$, are characterized by leading neutron production. They are dominated by $\\pi^+$ exchange and could provide us with more information about total and elastic $\\pi^+ p$ and $\\pi^+\\pi^+$ cross sections and parton distributions in pions in the still unexplored kinematical region.
R. A. Ryutin; A. E. Sobol; V. A. Petrov
Monte Carlo Comparisons to a Cryogenic Dark Matter Search Detector with Low Transition-Edge-Sensor Transition Temperature
We present results on phonon quasidiffusion and Transition Edge Sensor (TES) studies in a large, 3-inch diameter, 1-inch thick [100] high purity germanium crystal, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed with 59.5 keV gamma-rays from an Am-241 calibration source. We compare calibration data with results from a Monte Carlo which includes phonon quasidiffusion and the generation of phonons created by charge carriers as they are drifted across the detector by ionization readout channels. The phonon energy is then parsed into TES based phonon readout channels and input into a TES simulator.
Leman, S.W.; McCarthy, K.A.; /MIT, MKI; Brink, P.L.; Cabrera, B.; Cherry, M.; /Stanford U., Phys. Dept.; Silva, E.Do Couto E; /SLAC; Figueroa-Feliciano, E.; /MIT, MKI; Kim, P.; /SLAC; Mirabolfathi, N.; /UC, Berkeley; Pyle, M.; /Stanford U., Phys. Dept.; Resch, R.; /SLAC; Sadoulet, B.; Serfass, B.; Sundqvist, K.M.; /UC, Berkeley; Tomada, A.; /Stanford U., Phys. Dept.; Young, B.A.; /Santa Clara U.
Development of Monte Carlo Simulation Code to Model Behavior of Hydrogen Isotopes Loaded into Tungsten Containing Vacancies
The behavior of hydrogen isotopes implanted into tungsten containing vacancies was simulated using a Monte Carlo technique. The correlations between the distribution of implanted deuterium and fluence, trap density and trap distribution were evaluated. Throughout the present study, qualitatively understandable results were obtained. In order to improve the precision of the model and obtain quantitatively reliable results, it is necessary to deal with the following subjects: (1) how to balance long-time irradiation processes with a rapid diffusion process, (2) how to prevent unrealistic accumulation of hydrogen, and (3) how to model the release of hydrogen forcibly loaded into a region where hydrogen densely exist already.
T. Oda; M. Shimada; K. Zhang; P. Calderoni; Y. Oya; M. Sokolov; R. Kolasinski
Review Article: Physics and Monte Carlo Techniques as Relevant to Cryogenic, Phonon and Ionization Readout of CDMS Radiation-Detectors
This review discusses detector physics and Monte Carlo techniques for cryogenic, radiation detectors that utilize combined phonon and ionization readout. A general review of cryogenic phonon and charge transport is provided along with specific details of the Cryogenic Dark Matter Search detector instrumentation. In particular this review covers quasidiffusive phonon transport, which includes phonon focusing, anharmonic decay and isotope scattering. The interaction of phonons in the detector surface is discussed along with the downconversion of phonons in superconducting films. The charge transport physics include a mass tensor which results from the crystal band structure and is modeled with a Herring Vogt transformation. Charge scattering processes involve the creation of Neganov-Luke phonons. Transition-edge-sensor (TES) simulations include a full electric circuit description and all thermal processes including Joule heating, cooling to the substrate and thermal diffusion within the TES, the latter of which is necessary to model normal-superconducting phase separation. Relevant numerical constants are provided for these physical processes in germanium, silicon, aluminum and tungsten. Random number sampling methods including inverse cumulative distribution function (CDF) and rejection techniques are reviewed. To improve the efficiency of charge transport modeling, an additional second order inverse CDF method is developed here along with an efficient barycentric coordinate sampling method of electric fields. Results are provided in a manner that is convenient for use in Monte Carlo and references are provided for validation of these models.
S. W. Leman
For the first time, we report a unified microscopic-macroscopic Monte Carlo simulation of gas-grain chemistry in cold interstellar clouds in which both the gas-phase and the grain-surface chemistry are simulated by a stochastic technique. The surface chemistry is simulated with a microscopic Monte Carlo method in which the chemistry occurs on an initially flat surface. The surface chemical network consists of 29 reactions initiated by the accreting species H, O, C, and CO. Four different models are run with diverse but homogeneous physical conditions including temperature, gas density, and diffusion-barrier-to-desorption energy ratio. As time increases, icy interstellar mantles begin to grow. Our approach allows us to determine the morphology of the ice, layer by layer, as a function of time, and to ascertain the environment or environments for individual molecules. Our calculated abundances can be compared with observations of ices and gas-phase species, as well as the results of other models.
Chang Qiang [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Herbst, Eric [Also at Departments of Astronomy and Physics, University of Virginia, Charlottesville, VA 22904, USA. (United States)
Mercury + VisIt: Integration of a Real-Time Graphical Analysis Capability into a Monte Carlo Transport Code
Validation of the problem definition and analysis of the results (tallies) produced during a Monte Carlo particle transport calculation can be a complicated, time-intensive processes. The time required for a person to create an accurate, validated combinatorial geometry (CG) or mesh-based representation of a complex problem, free of common errors such as gaps and overlapping cells, can range from days to weeks. The ability to interrogate the internal structure of a complex, three-dimensional (3-D) geometry, prior to running the transport calculation, can improve the user's confidence in the validity of the problem definition. With regard to the analysis of results, the process of extracting tally data from printed tables within a file is laborious and not an intuitive approach to understanding the results. The ability to display tally information overlaid on top of the problem geometry can decrease the time required for analysis and increase the user's understanding of the results. To this end, our team has integrated VisIt, a parallel, production-quality visualization and data analysis tool into Mercury, a massively-parallel Monte Carlo particle transport code. VisIt provides an API for real time visualization of a simulation as it is running. The user may select which plots to display from the VisIt GUI, or by sending VisIt a Python script from Mercury. The frequency at which plots are updated can be set and the user can visualize the simulation results as it is running.
O'Brien, M J; Procassini, R J; Joy, K I
Molecular properties by Quantum Monte Carlo: an investigation on the role of the wave function ansatz and the basis set in the water molecule
Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their efficient parallelization, particularly suited for the modern high performance computing facilities. The ansatz of the wave function and its variational flexibility are crucial points for both the accurate description of molecular properties and the capabilities of the method to tackle large systems. In this paper, we extensively analyze, using different variational ansatzes, several properties of the water molecule, namely: the total energy, the dipole and quadrupole momenta, the ionization and atomization energies, the equilibrium configuration, and the harmonic and fundamental frequencies of vibration. The investigation mainly focuses on variational Monte Carlo calculations, although several lattice regularized diffusion Monte Carlo calculations are also reported. Throu...
Zen, Andrea; Sorella, Sandro; Guidoni, Leonardo
Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition
Purpose: The objective of this work is to assess the sensitivity of Monte Carlo (MC) dose calculations to uncertainties in human tissue composition for a range of low photon energy brachytherapy sources: {sup 125}I, {sup 103}Pd, {sup 131}Cs, and an electronic brachytherapy source (EBS). The low energy photons emitted by these sources make the dosimetry sensitive to variations in tissue atomic number due to the dominance of the photoelectric effect. This work reports dose to a small mass of water in medium D{sub w,m} as opposed to dose to a small mass of medium in medium D{sub m,m}. Methods: Mean adipose, mammary gland, and breast tissues (as uniform mixture of the aforementioned tissues) are investigated as well as compositions corresponding to one standard deviation from the mean. Prostate mean compositions from three different literature sources are also investigated. Three sets of MC simulations are performed with the GEANT4 code: (1) Dose calculations for idealized TG-43-like spherical geometries using point sources. Radial dose profiles obtained in different media are compared to assess the influence of compositional uncertainties. (2) Dose calculations for four clinical prostate LDR brachytherapy permanent seed implants using {sup 125}I seeds (Model 2301, Best Medical, Springfield, VA). The effect of varying the prostate composition in the planning target volume (PTV) is investigated by comparing PTV D{sub 90} values. (3) Dose calculations for four clinical breast LDR brachytherapy permanent seed implants using {sup 103}Pd seeds (Model 2335, Best Medical). The effects of varying the adipose/gland ratio in the PTV and of varying the elemental composition of adipose and gland within one standard deviation of the assumed mean composition are investigated by comparing PTV D{sub 90} values. For (2) and (3), the influence of using the mass density from CT scans instead of unit mass density is also assessed. Results: Results from simulation (1) show that variations in the mean compositions of tissues affect low energy brachytherapy dosimetry. Dose differences between mean and one standard deviation of the mean composition increasing with distance from the source are observed. It is established that the {sup 125}I and {sup 131}Cs sources are the least sensitive to variations in elemental compositions while {sup 103}Pd is most sensitive. The EBS falls in between and exhibits complex behavior due to significant spectral hardening. Results from simulation (2) show that two prostate compositions are dosimetrically equivalent to water while the third shows D{sub 90} differences of up to 4%. Results from simulation (3) show that breast is more sensitive than prostate with dose variations of up to 30% from water for 70% adipose/30% gland breast. The variability of the breast composition adds a {+-}10% dose variation. Conclusions: Low energy brachytherapy dose distributions in tissue differ from water and are influenced by density, mean tissue composition, and patient-to-patient composition variations. The results support the use of a dose calculation algorithm accounting for heterogeneities such as MC. Since this work shows that variations in mean tissue compositions affect MC dosimetry and result in increased dose uncertainties, the authors conclude that imaging tools providing more accurate estimates of elemental compositions such as dual energy CT would be beneficial.
Landry, Guillaume; Reniers, Brigitte; Murrer, Lars; Lutgens, Ludy; Bloemen-Van Gurp, Esther; Pignol, Jean-Philippe; Keller, Brian; Beaulieu, Luc; Verhaegen, Frank [Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, de l'Universite Laval, CHUQ, Pavillon L'Hotel-Dieu de Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec G1K 7P4 (Canada); Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands) and Medical Physics Unit, McGill University, Montreal General Hospital, Montreal, Quebec H3G 1A4 (Canada)
Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study
Purpose: To demonstrate the feasibility of photon energy-modulated radiotherapy during beam-on time. Methods: A cylindrical device made of aluminum was conceptually proposed as an energy modulator. The frame of the device was connected with 20 tubes through which mercury could be injected or drained to adjust the thickness of mercury along the beam axis. In Monte Carlo (MC) simulations, a flattening filter of 6 or 10 MV linac was replaced with the device. The thickness of mercury inside the device varied from 0 to 40 mm at the field sizes of 5 x 5 cm{sup 2} (FS5), 10 x 10 cm{sup 2} (FS10), and 20 x 20 cm{sup 2} (FS20). At least 5 billion histories were followed for each simulation to create phase space files at 100 cm source to surface distance (SSD). In-water beam data were acquired by additional MC simulations using the above phase space files. A treatment planning system (TPS) was commissioned to generate a virtual machine using the MC-generated beam data. Intensity modulated radiation therapy (IMRT) plans for six clinical cases were generated using conventional 6 MV, 6 MV flattening filter free, and energy-modulated photon beams of the virtual machine. Results: As increasing the thickness of mercury, Percentage depth doses (PDD) of modulated 6 and 10 MV after the depth of dose maximum were continuously increased. The amount of PDD increase at the depth of 10 and 20 cm for modulated 6 MV was 4.8% and 5.2% at FS5, 3.9% and 5.0% at FS10 and 3.2%-4.9% at FS20 as increasing the thickness of mercury from 0 to 20 mm. The same for modulated 10 MV was 4.5% and 5.0% at FS5, 3.8% and 4.7% at FS10 and 4.1% and 4.8% at FS20 as increasing the thickness of mercury from 0 to 25 mm. The outputs of modulated 6 MV with 20 mm mercury and of modulated 10 MV with 25 mm mercury were reduced into 30%, and 56% of conventional linac, respectively. The energy-modulated IMRT plans had less integral doses than 6 MV IMRT or 6 MV flattening filter free plans for tumors located in the periphery while maintaining the similar quality of target coverage, homogeneity, and conformity. Conclusions: The MC study for the designed energy modulator demonstrated the feasibility of energy-modulated photon beams available during beam-on time. The planning study showed an advantage of energy-and intensity modulated radiotherapy in terms of integral dose without sacrificing any quality of IMRT plan.
Park, Jong Min; Kim, Jung-in; Heon Choi, Chang; Chie, Eui Kyu; Kim, Il Han; Ye, Sung-Joon [Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744, Korea and Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of) and Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of); Interdiciplinary Program in Radiation Applied Life Science, Seoul National University, Seoul, 110-744 (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul, 110-744 (Korea, Republic of) and Department of Intelligent Convergence Systems, Seoul National University, Seoul, 151-742 (Korea, Republic of)
Fast patient-specific Monte Carlo brachytherapy dose calculations via the correlated sampling variance reduction technique
Purpose: To demonstrate potential of correlated sampling Monte Carlo (CMC) simulation to improve the calculation efficiency for permanent seed brachytherapy (PSB) implants without loss of accuracy. Methods: CMC was implemented within an in-house MC code family (PTRAN) and used to compute 3D dose distributions for two patient cases: a clinical PSB postimplant prostate CT imaging study and a simulated post lumpectomy breast PSB implant planned on a screening dedicated breast cone-beam CT patient exam. CMC tallies the dose difference, {Delta}D, between highly correlated histories in homogeneous and heterogeneous geometries. The heterogeneous geometry histories were derived from photon collisions sampled in a geometrically identical but purely homogeneous medium geometry, by altering their particle weights to correct for bias. The prostate case consisted of 78 Model-6711 {sup 125}I seeds. The breast case consisted of 87 Model-200 {sup 103}Pd seeds embedded around a simulated lumpectomy cavity. Systematic and random errors in CMC were unfolded using low-uncertainty uncorrelated MC (UMC) as the benchmark. CMC efficiency gains, relative to UMC, were computed for all voxels, and the mean was classified in regions that received minimum doses greater than 20%, 50%, and 90% of D{sub 90}, as well as for various anatomical regions. Results: Systematic errors in CMC relative to UMC were less than 0.6% for 99% of the voxels and 0.04% for 100% of the voxels for the prostate and breast cases, respectively. For a 1 x 1 x 1 mm{sup 3} dose grid, efficiency gains were realized in all structures with 38.1- and 59.8-fold average gains within the prostate and breast clinical target volumes (CTVs), respectively. Greater than 99% of the voxels within the prostate and breast CTVs experienced an efficiency gain. Additionally, it was shown that efficiency losses were confined to low dose regions while the largest gains were located where little difference exists between the homogeneous and heterogeneous doses. On an AMD 1090T processor, computing times of 38 and 21 sec were required to achieve an average statistical uncertainty of 2% within the prostate (1 x 1 x 1 mm{sup 3}) and breast (0.67 x 0.67 x 0.8 mm{sup 3}) CTVs, respectively. Conclusions: CMC supports an additional average 38-60 fold improvement in average efficiency relative to conventional uncorrelated MC techniques, although some voxels experience no gain or even efficiency losses. However, for the two investigated case studies, the maximum variance within clinically significant structures was always reduced (on average by a factor of 6) in the therapeutic dose range generally. CMC takes only seconds to produce an accurate, high-resolution, low-uncertainly dose distribution for the low-energy PSB implants investigated in this study.
Sampson, Andrew; Le Yi; Williamson, Jeffrey F. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)
A Unified Monte Carlo Approach to Fast Neutron Cross Section Data Evaluation - NUCLEAR DATA AND MEASUREMENT SERIES
NUCLEAR DATA AND MEASUREMENT SERIES NUCLEAR DATA AND MEASUREMENT SERIES ANL/NDM-166 A Unified Monte Carlo Approach to Fast Neutron Cross Section Data Evaluation Donald L. Smith January 2008 NUCLEAR ENGINEERING DIVISION ARGONNE NATIONAL LABORATORY 9700 SOUTH CASS AVENUE ARGONNE, ILLINOIS 60439, U.S.A. 1 About Argonne National Laboratory Argonne is a U.S. Department of Energy laboratory managed by UChicago Argonne, LLC under contract DE-AC02-06CH11357. The Laboratory's main facility is in the suburbs of Chicago at 9700 South Cass Avenue, Argonne, Illinois 60439. For information about Argonne National Laboratory see http://www.anl.gov. Availability of this Report This report is available, at no cost, at http://www.osti.gov/bridge. It is also available on paper from the U.S. Department of Energy and its contractors, for a processing fee, from:
Application of Distribution Transformer Thermal Life Models to Electrified Vehicle Charging Loads Using Monte-Carlo Method: Preprint
Application of Distribution Application of Distribution Transformer Thermal Life Models to Electrified Vehicle Charging Loads Using Monte-Carlo Method Preprint Michael Kuss, Tony Markel, and William Kramer Presented at the 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition Shenzhen, China November 5 - 9, 2010 Conference Paper NREL/CP-5400-48827 January 2011 NOTICE The submitted manuscript has been offered by an employee of the Alliance for Sustainable Energy, LLC (Alliance), a contractor of the US Government under Contract No. DE-AC36-08GO28308. Accordingly, the US Government and Alliance retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes.
Monte-Carlo and Variational Calculations of the Magnetic Phase Diagram of CuFeO2
Monte-Carlo and variational calculations are used to revise the phase diagram of the magnetically- frustrated material CuFeO2. For fields 50 T < H < 65 T, a new spin flop phase is predicted between a canted three-sublattice phase and the conventional conical spin-flop phase. This phase has wavevector Q (0.8 , 0.43 ) and is commensurate in the x direction but incommensurate in the y direction. A canted five-sublattice phase is predicted between the multiferroic phase and either a collinear five-sublattice phase for pure CuFeO2 or a canted three-sublattice phase for Al- or Ga-doped CuFeO2.
Fishman, Randy Scott [ORNL; Brown, Gregory [Florida State University; Haraldsen, Jason T [ORNL; Haraldsen, Jason T. [Los Alamos National Laboratory (LANL)
Monte Carlo calculations of the effective area and directional response of a polyethylene-moderated neutron counter
Two recent reports on Monte Carlo studies have examined the angular response of a multiple-rod neutron scintillator and the energy response of a moderated {sup 3}He neutron counter. This report extends those studies to provide calculations of the effective area and angular sensitivity of a polyethylene-moderated neutron detector that has multiple {sup 3}He tubes. The results (1) provide a more accurate and general determination of the sensor`s detection efficiency, (2) suggest new techniques for obtaining information about the source direction, and (3) allow evaluation of proposals to improve the high-energy detection efficiency by using the production of (n,2n) neutrons in high-density material added to the moderator.
Nuclear interactions of 160 MeV protons stopping in copper: A test of Monte Carlo nuclear models
To estimate the influence of nuclear interactions on dose or biological effect one uses Monte Carlo programs which include nuclear models. We introduce an experimental method to check these models at proton therapy energies. We have measured the distribution of charge deposited by 160 MeV protons stopping in a stack of insulated copper plates. A buildup region ahead of the main peak contains ?20% of the total charge and is entirely due to charged secondaries from inelastic nuclear interactions. The acceptance for charged secondaries is 100%. Therefore the data are a good benchmark for nuclear models. We have simulated the stack using GEANT with two nuclear models.FLUKA agrees fairly well with the measurement but GHEISHA
Bernard Gottschalk; Rachel Platais; Harald Paganetti
Benchmark of Atucha-2 PHWR RELAP5-3D control rod model by Monte Carlo MCNP5 core calculation
Atucha-2 is a Siemens-designed PHWR reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarities require the adoption of advanced Monte Carlo codes for performing realistic neutronic simulations. Therefore core models of Atucha-2 PHWR were developed using MCNP5. In this work a methodology was set up to collect the flux in the hexagonal mesh by which the Atucha-2 core is represented. The scope of this activity is to evaluate the effect of obliquely inserted control rod on neutron flux in order to validate the RELAP5-3D{sup C}/NESTLE three dimensional neutron kinetic coupled thermal-hydraulic model, applied by GRNSPG/UNIPI for performing selected transients of Chapter 15 FSAR of Atucha-2. (authors)
Pecchia, M.; D'Auria, F. [San Piero A Grado Nuclear Research Group GRNSPG, Univ. of Pisa, via Diotisalvi, 2, 56122 - Pisa (Italy); Mazzantini, O. [Nucleo-electrica Argentina Societad Anonima NA-SA, Buenos Aires (Argentina)
Monte Carlo Studies of Geomagnetic Field Effects on the Imaging Air Cherenkov Technique for the MAGIC Telescope Site
Imaging air Cherenkov telescopes (IACTs) detect the Cherenkov light from extensive air showers (EAS) initiated by very high energy (VHE) gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is vital. The influence of the geomagnetic field (GF) on the development of EAS can further complicate the imaging air Cherenkov technique. The amount and the angular distribution of Cherenkov light from EAS can be obtained by means of Monte Carlo (MC) simulations. Here we present the results from dedicated MC studies of GF effects on images from gamma-ray initiated EAS for the MAGIC telescope site, where the GF strength is ~40 micro Tesla. The results from the MC studies suggest that GF effects degrade not only measurements of very low energy gamma-rays below ~100 GeV but also those at TeV-energies.
S. C. Commichau; A. Biland; J. L. Contreras; R. de los Reyes; A. Moralejo; J. Sitarek; D. Sobczynska
Monte-Carlo Modeling of Parameters of a Subcritical Cascade Reactor Based on MSBR and LMFBR Technologies
Parameters of a subcritical cascade reactor driven by a proton accelerator and based on a primary lead-bismuth target, main reactor constructed analogously to the molten salt breeder (MSBR) reactor core and a booster-reactor analogous to the core of the BN-350 liquid metal cooled fast breeder reactor (LMFBR). It is shown by means of Monte-Carlo modeling that the reactor under study provides safe operation modes (k_{eff}=0.94-0.98), is apable to transmute effectively radioactive nuclear waste and reduces by an order of magnitude the requirements on the accelerator beam current. Calculations show that the maximal neutron flux in the thermal zone is 10^{14} cm^{12}\\cdot s^_{-1}, in the fast booster zone is 5.12\\cdot10^{15} cm^{12}\\cdot s{-1} at k_{eff}=0.98 and proton beam current I=2.1 mA.
Bznuni, S A; Zhamkochyan, V M; Polanski, A; Sosnin, A N; Khudaverdyan, A H
Efficient Estimation of Highly Structured Posteriors of Gravitational-Wave Signals with Markov-Chain Monte Carlo
We introduce a new Markov-Chain Monte Carlo (MCMC) approach designed for efficient sampling of highly correlated and multimodal posteriors. Parallel tempering, though effective, is a costly technique for sampling such posteriors. Our approach minimizes the use of parallel tempering, only using it for a short time to tune a new jump proposal. For complex posteriors we find efficiency improvements up to a factor of ~13. The estimation of parameters of gravitational-wave signals measured by ground-based detectors is currently done through Bayesian inference with MCMC one of the leading sampling methods. Posteriors for these signals are typically multimodal with strong non-linear correlations, making sampling difficult. As we enter the advanced-detector era, improved sensitivities and wider bandwidths will drastically increase the computational cost of analyses, demanding more efficient search algorithms to meet these challenges.
Farr, Benjamin; Luijten, Erik
On Monte Carlo modeling of megavoltage photon beams: A revisited study on the sensitivity of beam parameters
Purpose: To commission Monte Carlo beam models for five Varian megavoltage photon beams (4, 6, 10, 15, and 18 MV). The goal is to closely match measured dose distributions in water for a wide range of field sizes (from 2x2 to 35x35 cm{sup 2}). The second objective is to reinvestigate the sensitivity of the calculated dose distributions to variations in the primary electron beam parameters. Methods: The GEPTS Monte Carlo code is used for photon beam simulations and dose calculations. The linear accelerator geometric models are based on (i) manufacturer specifications, (ii) corrections made by Chibani and Ma [''On the discrepancies between Monte Carlo dose calculations and measurements for the 18 MV Varian photon beam,'' Med. Phys. 34, 1206-1216 (2007)], and (iii) more recent drawings. Measurements were performed using pinpoint and Farmer ionization chambers, depending on the field size. Phase space calculations for small fields were performed with and without angle-based photon splitting. In addition to the three commonly used primary electron beam parameters (E{sub AV} is the mean energy, FWHM is the energy spectrum broadening, and R is the beam radius), the angular divergence ({theta}) of primary electrons is also considered. Results: The calculated and measured dose distributions agreed to within 1% local difference at any depth beyond 1 cm for different energies and for field sizes varying from 2x2 to 35x35 cm{sup 2}. In the penumbra regions, the distance to agreement is better than 0.5 mm, except for 15 MV (0.4-1 mm). The measured and calculated output factors agreed to within 1.2%. The 6, 10, and 18 MV beam models use {theta}=0 deg., while the 4 and 15 MV beam models require {theta}=0.5 deg. and 0.6 deg., respectively. The parameter sensitivity study shows that varying the beam parameters around the solution can lead to 5% differences with measurements for small (e.g., 2x2 cm{sup 2}) and large (e.g., 35x35 cm{sup 2}) fields, while a perfect agreement is maintained for the 10x10 cm{sup 2} field. The influence of R on the central-axis depth dose and the strong influence of {theta} on the lateral dose profiles are demonstrated. Conclusions: Dose distributions for very small and very large fields were proved to be more sensitive to variations in E{sub AV}, R, and {theta} in comparison with the 10x10 cm{sup 2} field. Monte Carlo beam models need to be validated for a wide range of field sizes including small field sizes (e.g., 2x2 cm{sup 2}).
Chibani, Omar; Moftah, Belal; Ma, C.-M. Charlie [Department of Biomedical Physics, King Faisal Specialist Hospital and Research Center, Riyadh 11211 (Saudi Arabia) and Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States); Department of Biomedical Physics, King Faisal Specialist Hospital and Research Center, Riyadh 11211 (Saudi Arabia); Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)
Predicting fissile content of spent nuclear fuel assemblies with the passive neutron Albedo reactivity technique and Monte Carlo code emulation
There is a great need in the safeguards community to be able to nondestructively quantify the mass of plutonium of a spent nuclear fuel assembly. As part of the Next Generation of Safeguards Initiative, we are investigating several techniques, or detector systems, which, when integrated, will be capable of quantifying the plutonium mass of a spent fuel assembly without dismantling the assembly. This paper reports on the simulation of one of these techniques, the Passive Neutron Albedo Reactivity with Fission Chambers (PNAR-FC) system. The response of this system over a wide range of spent fuel assemblies with different burnup, initial enrichment, and cooling time characteristics is shown. A Monte Carlo method of using these modeled results to estimate the fissile content of a spent fuel assembly has been developed. A few numerical simulations of using this method are shown. Finally, additional developments still needed and being worked on are discussed.
Conlin, Jeremy Lloyd [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory
Electron Irradiation of Conjunctival Lymphoma-Monte Carlo Simulation of the Minute Dose Distribution and Technique Optimization
Purpose: External beam radiotherapy is the only conservative curative approach for Stage I non-Hodgkin lymphomas of the conjunctiva. The target volume is geometrically complex because it includes the eyeball and lid conjunctiva. Furthermore, the target volume is adjacent to radiosensitive structures, including the lens, lacrimal glands, cornea, retina, and papilla. The radiotherapy planning and optimization requires accurate calculation of the dose in these anatomical structures that are much smaller than the structures traditionally considered in radiotherapy. Neither conventional treatment planning systems nor dosimetric measurements can reliably determine the dose distribution in these small irradiated volumes. Methods and Materials: The Monte Carlo simulations of a Varian Clinac 2100 C/D and human eye were performed using the PENELOPE and PENEASYLINAC codes. Dose distributions and dose volume histograms were calculated for the bulbar conjunctiva, cornea, lens, retina, papilla, lacrimal gland, and anterior and posterior hemispheres. Results: The simulated results allow choosing the most adequate treatment setup configuration, which is an electron beam energy of 6 MeV with additional bolus and collimation by a cerrobend block with a central cylindrical hole of 3.0 cm diameter and central cylindrical rod of 1.0 cm diameter. Conclusions: Monte Carlo simulation is a useful method to calculate the minute dose distribution in ocular tissue and to optimize the electron irradiation technique in highly critical structures. Using a voxelized eye phantom based on patient computed tomography images, the dose distribution can be estimated with a standard statistical uncertainty of less than 2.4% in 3 min using a computing cluster with 30 cores, which makes this planning technique clinically relevant.
Brualla, Lorenzo, E-mail: email@example.com [NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Essen (Germany); Zaragoza, Francisco J.; Sempau, Josep [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Barcelona (Spain); Wittig, Andrea [Department of Radiation Oncology, University Hospital Giessen and Marburg, Philipps-University Marburg, Marburg (Germany); Sauerwein, Wolfgang [NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Essen (Germany)
Validation of a virtual source model for Monte Carlo dose calculations of a flattening filter free linac
Purpose: A linac delivering intensity-modulated radiotherapy (IMRT) can benefit from a flattening filter free (FFF) design which offers higher dose rates and reduced accelerator head scatter than for conventional (flattened) delivery. This reduction in scatter simplifies beam modeling, and combining a Monte Carlo dose engine with a FFF accelerator could potentially increase dose calculation accuracy. The objective of this work was to model a FFF machine using an adapted version of a previously published virtual source model (VSM) for Monte Carlo calculations and to verify its accuracy. Methods: An Elekta Synergy linear accelerator operating at 6 MV has been modified to enable irradiation both with and without the flattening filter (FF). The VSM has been incorporated into a commercially available treatment planning system (Monaco Trade-Mark-Sign v 3.1) as VSM 1.6. Dosimetric data were measured to commission the treatment planning system (TPS) and the VSM adapted to account for the lack of angular differential absorption and general beam hardening. The model was then tested using standard water phantom measurements and also by creating IMRT plans for a range of clinical cases. Results: The results show that the VSM implementation handles the FFF beams very well, with an uncertainty between measurement and calculation of <1% which is comparable to conventional flattened beams. All IMRT beams passed standard quality assurance tests with >95% of all points passing gamma analysis ({gamma} < 1) using a 3%/3 mm tolerance. Conclusions: The virtual source model for flattened beams was successfully adapted to a flattening filter free beam production. Water phantom and patient specific QA measurements show excellent results, and comparisons of IMRT plans generated in conventional and FFF mode are underway to assess dosimetric uncertainties and possible improvements in dose calculation and delivery.
Cashmore, Jason; Golubev, Sergey; Dumont, Jose Luis; Sikora, Marcin; Alber, Markus; Ramtohul, Mark [Hall-Edwards Radiotherapy Research Group, University Hospital Birmingham NHS Foundation Trust, United Kingdom, B15 2TH (United Kingdom); Elekta CMS Software, St. Louis, Missouri 63043 (United States); Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen 5021 (Norway); Section for Biomedical Physics, University Hospital for Radiation Oncology, Hoppe-Seyler-Str 3, 72076, Tuebingen (Germany); Hall-Edwards Radiotherapy Research Group, University Hospital Birmingham NHS Foundation Trust, United Kingdom, B15 2TH (United Kingdom)
Monte Carlo calculated TG-60 dosimetry parameters for the {beta}{sup -} emitter {sup 153}Sm brachytherapy source
Purpose: The formalism recommended by Task Group 60 (TG-60) of the American Association of Physicists in Medicine (AAPM) is applicable for {beta} sources. Radioactive biocompatible and biodegradable {sup 153}Sm glass seed without encapsulation is a {beta}{sup -} emitter radionuclide with a short half-life and delivers a high dose rate to the tumor in the millimeter range. This study presents the results of Monte Carlo calculations of the dosimetric parameters for the {sup 153}Sm brachytherapy source. Methods: Version 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate two-dimensional dose distributions around the source. The dosimetric parameters of AAPM TG-60 recommendations including the reference dose rate, the radial dose function, the anisotropy function, and the one-dimensional anisotropy function were obtained. Results: The dose rate value at the reference point was estimated to be 9.21{+-}0.6 cGy h{sup -1} {mu}Ci{sup -1}. Due to the low energy beta emitted from {sup 153}Sm sources, the dose fall-off profile is sharper than the other beta emitter sources. The calculated dosimetric parameters in this study are compared to several beta and photon emitting seeds. Conclusions: The results show the advantage of the {sup 153}Sm source in comparison with the other sources because of the rapid dose fall-off of beta ray and high dose rate at the short distances of the seed. The results would be helpful in the development of the radioactive implants using {sup 153}Sm seeds for the brachytherapy treatment.
Sadeghi, Mahdi; Taghdiri, Fatemeh; Hamed Hosseini, S.; Tenreiro, Claudio [Agricultural, Medical and Industrial School, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of); Engineering Faculty, Research and Science Campus, Islamic Azad University, Tehran (Iran, Islamic Republic of); Department of Energy Science, SungKyunKwan University, 300 Cheoncheon-dong, Suwon (Korea, Republic of)
Lower and upper bounds for the absolute free energy by the hypothetical scanning Monte Carlo method: Application to liquid argon and water
Lower and upper bounds for the absolute free energy by the hypothetical scanning Monte Carlo method The hypothetical scanning HS method is a general approach for calculating the absolute entropy S and free energy F to provide the free energy through the analysis of a single configuration. © 2004 American Institute
Meirovitch, Hagai
PHYSICAL REVIEW C 83, 064612 (2011) Advanced Monte Carlo modeling of prompt fission neutrons for thermal and fast neutron-induced
PHYSICAL REVIEW C 83, 064612 (2011) Advanced Monte Carlo modeling of prompt fission neutrons of the 6th All Union Conference on Neutron Physics, Kiev, 26 October 1983, p. 285, EXFOR entry 40871, A. F. Semenov, and B. I. Starostov, Proceedings of the 6th All Union Conference on Neutron Physics
Orange, California: Energy Resources | Open Energy Information
7877944°, -117.8531119° 7877944°, -117.8531119° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":33.7877944,"lon":-117.8531119,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Orange, Ohio: Energy Resources | Open Energy Information
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Orange County - OCHEEP! (Florida) | Open Energy Information
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Trusted Computer System Evaluation Criteria ["Orange Book"
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Changes in dose with segmentation of breast tissues in Monte Carlo calculations for low-energy brachytherapy
Purpose: To investigate the use of various breast tissue segmentation models in Monte Carlo dose calculations for low-energy brachytherapy. Methods: The EGSnrc user-code BrachyDose is used to perform Monte Carlo simulations of a breast brachytherapy treatment using TheraSeed Pd-103 seeds with various breast tissue segmentation models. Models used include a phantom where voxels are randomly assigned to be gland or adipose (randomly segmented), a phantom where a single tissue of averaged gland and adipose is present (averaged tissue), and a realistically segmented phantom created from previously published numerical phantoms. Radiation transport in averaged tissue while scoring in gland along with other combinations is investigated. The inclusion of calcifications in the breast is also studied in averaged tissue and randomly segmented phantoms. Results: In randomly segmented and averaged tissue phantoms, the photon energy fluence is approximately the same; however, differences occur in the dose volume histograms (DVHs) as a result of scoring in the different tissues (gland and adipose versus averaged tissue), whose mass energy absorption coefficients differ by 30%. A realistically segmented phantom is shown to significantly change the photon energy fluence compared to that in averaged tissue or randomly segmented phantoms. Despite this, resulting DVHs for the entire treatment volume agree reasonably because fluence differences are compensated by dose scoring differences. DVHs for the dose to only the gland voxels in a realistically segmented phantom do not agree with those for dose to gland in an averaged tissue phantom. Calcifications affect photon energy fluence to such a degree that the differences in fluence are not compensated for (as they are in the no calcification case) by dose scoring in averaged tissue phantoms. Conclusions: For low-energy brachytherapy, if photon transport and dose scoring both occur in an averaged tissue, the resulting DVH for the entire treatment volume is reasonably accurate because inaccuracies in photon energy fluence are compensated for by inaccuracies in localized dose scoring. If dose to fibroglandular tissue in the breast is of interest, then the inaccurate photon energy fluence calculated in an averaged tissue phantom will result in inaccurate DVHs and average doses for those tissues. Including calcifications necessitates the use of proper tissue segmentation.
Sutherland, J. G. H.; Thomson, R. M.; Rogers, D. W. O. [Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa K1S 5B6 (Canada)
Inference of the optimal pretarget electron beam parameters in a Monte Carlo virtual linac model through simulated annealing
The purpose of this study was to develop an efficient method to determine the optimal intensity distribution of the pretarget electron beam in a Monte Carlo (MC) accelerator model able to most accurately reproduce a set of measured photon field profiles for a given accelerator geometry and nominal photon beam energy. The method has the ability to reduce the number of simulations required to commission a MC accelerator model and has achieved better agreement with measurement than other methods described in literature. The method begins from a cylindrically symmetric pretarget electron beam (radius of 0.5 cm) of uniform intensity. This beam is subdivided into annular regions of fluence for which each region is individually transported through the accelerator head and into a water phantom. A simulated annealing search is then performed to determine the optimal combination of weights of the annular fluences that provide a best match between the measured dose distributions and the weighted sum of annular dose distributions for particular pretarget electron energy. When restricted to Gaussian intensity distributions, the optimization determined an optimal FWHM=1.34 mm for 18.0 MeV electrons, with a RMSE=0.49% on 40x40 cm{sup 2} lateral profiles. When allowed to deviate from Gaussian intensities a further reduction in RMSE was achieved. For our Clinac 21 EX accelerator MC model (based on the 1996 Varian Oncology Systems, Monte Carlo Project package), the optimal unrestricted intensity distribution was found to be a Gaussian-like solution (18.0 MeV, FWHM=1.10 mm, 40x40 cm{sup 2} profile, and RMSE=0.15%) with the presence of an extra focal halo contribution on the order of 10% of the maximum Gaussian intensity. Using the optimally derived intensity, 10x10 and 4x4 cm{sup 2} profiles were found to be in agreement with measurement with a maximum RMSE=0.49%. The optimized Gaussian and unrestricted values of the electron beam FWHM were both within the range of those inferred by focal spot image measurements performed by Jaffray et al.[''X-ray sources of medical linear accelerators: Focal and extra-focal radiation,'' Med. Phys. 20, 1417-1427 (1993)]. The inference of an extra focal pretarget electron component may be an indicator of a deficiency in the MC model and needs further investigation.
Bush, Karl; Zavgorodni, Sergei; Beckham, Wayne [Department of Physics and Astronomy, University of Victoria, P. O. Box 3055 STN CSC, Victoria, British Columbia V8W 3P6 (Canada); Department of Medical Physics, British Columbia Cancer Agency-Vancouver Island Center, Victoria, British Columbia V8R 6V5 (Canada) and Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8R 6V5 (Canada)
Validation of a Monte Carlo based depletion methodology via High Flux Isotope Reactor HEU post-irradiation examination measurements
The purpose of this study is to validate a Monte Carlo based depletion methodology by comparing calculated post-irradiation uranium isotopic compositions in the fuel elements of the High Flux Isotope Reactor (HFIR) core to values measured using uranium mass-spectrographic analysis. Three fuel plates were analyzed: two from the outer fuel element (OFE) and one from the inner fuel element (IFE). Fuel plates O-111-8, O-350-1, and I-417-24 from outer fuel elements 5-O and 21-O and inner fuel element 49-I, respectively, were selected for examination. Fuel elements 5-O, 21-O, and 49-1 were loaded into HFIR during cycles 4, 16, and 35, respectively (mid to late 1960s). Approximately one year after each of these elements were irradiated, they were transferred to the High Radiation Level Examination Laboratory (HRLEL) where samples from these fuel plates were sectioned and examined via uranium mass-spectrographic analysis. The isotopic composition of each of the samples was used to determine the atomic percent of the uranium isotopes. A Monte Carlo based depletion computer program, ALEPH, which couples the MCNP and ORIGEN codes, was utilized to calculate the nuclide inventory at the end-of-cycle (EOC). A current ALEPH/MCNP input for HFIR fuel cycle 400 was modified to replicate cycles 4, 16, and 35. The control element withdrawal curves and flux trap loadings were revised, as well as the radial zone boundaries and nuclide concentrations in the MCNP model. The calculated EOC uranium isotopic compositions for the analyzed plates were found to be in good agreement with measurements, which reveals that ALEPH/MCNP can accurately calculate burn-up dependent uranium isotopic concentrations for the HFIR core. The spatial power distribution in HFIR changes significantly as irradiation time increases due to control element movement. Accurate calculation of the end-of-life uranium isotopic inventory is a good indicator that the power distribution variation as a function of space and time is accurately calculated, i.e. an integral check. Hence, the time dependent heat generation source terms needed for reactor core thermal hydraulic analysis, if derived from this methodology, have been shown to be accurate for highly enriched uranium (HEU) fuel.
Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout
A detailed description of a compact Monte Carlo simulation code ''G3sim'' for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.
Mohanty, P. K.; Dugad, S. R.; Gupta, S. K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India)
A stochastic Monte Carlo approach to model real star cluster evolution; 2, Self-consistent models and primordial binaries
The new approach outlined in Paper I (Spurzem \\& Giersz 1996) to follow the individual formation and evolution of binaries in an evolving, equal point-mass star cluster is extended for the self-consistent treatment of relaxation and close three- and four-body encounters for many binaries (typically a few percent of the initial number of stars in the cluster). The distribution of single stars is treated as a conducting gas sphere with a standard anisotropic gaseous model. A Monte Carlo technique is used to model the motion of binaries, their formation and subsequent hardening by close encounters, and their relaxation (dynamical friction) with single stars and other binaries. The results are a further approach towards a realistic model of globular clusters with primordial binaries without using special hardware. We present, as our main result, the self-consistent evolution of a cluster consisting of 300.000 equal point-mass stars, plus 30.000 equal mass binaries over several hundred half-mass relaxation tim...
Giersz, M
Concentrated purchasing patterns of plug-in vehicles may result in localized distribution transformer overload scenarios. Prolonged periods of transformer overloading causes service life decrements, and in worst-case scenarios, results in tripped thermal relays and residential service outages. This analysis will review distribution transformer load models developed in the IEC 60076 standard, and apply the model to a neighborhood with plug-in hybrids. Residential distribution transformers are sized such that night-time cooling provides thermal recovery from heavy load conditions during the daytime utility peak. It is expected that PHEVs will primarily be charged at night in a residential setting. If not managed properly, some distribution transformers could become overloaded, leading to a reduction in transformer life expectancy, thus increasing costs to utilities and consumers. A Monte-Carlo scheme simulated each day of the year, evaluating 100 load scenarios as it swept through the following variables: number of vehicle per transformer, transformer size, and charging rate. A general method for determining expected transformer aging rate will be developed, based on the energy needs of plug-in vehicles loading a residential transformer.
Kuss, M.; Markel, T.; Kramer, W.
Time dependent simulations of multiwavelength variability of the blazar Mrk 421 with a Monte Carlo multi-zone code
(abridged) We present a new time-dependent multi-zone radiative transfer code and its application to study the SSC emission of Mrk 421. The code couples Fokker-Planck and Monte Carlo methods, in a 2D geometry. For the first time all the light travel time effects (LCTE) are fully considered, along with a proper treatment of Compton cooling, which depends on them. We study a set of simple scenarios where the variability is produced by injection of relativistic electrons as a `shock front' crosses the emission region. We consider emission from two components, with the second one either being pre-existing and co-spatial and participating in the evolution of the active region, or spatially separated and independent, only diluting the observed variability. Temporal and spectral results of the simulation are compared to the multiwavelength observations of Mrk 421 in March 2001. We find parameters that can adequately fit the observed SEDs and multiwavelength light curves and correlations. There remain however a few o...
Chen, Xuhui; Liang, Edison; Boettcher, Markus
ITS version 5.0 : the integrated TIGER series of coupled electron/photon Monte Carlo transport codes.
ITS is a powerful and user-friendly software package permitting state of the art Monte Carlo solution of linear time-independent couple electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fie