An exposure assessment survey of the Mont Belvieu polyethylene plant
Tucker, Thomas Franklin
1997-01-01T23:59:59.000Z
with exposure to each stressor. Exposure ratings and health effect ratings were combined on a matrix to give health-risk rankings. Stressors associated with each overall worker group and with individual tasks were ranked. These health-risk rankings were...
1. DNA microarray DNA (spot) . DNA probe , probe (hybridization) . DNA microarray cDNA oligonucleotide oligonucleotide cDNA probe . oligonucleotide microarray , DNA , probe . oligonucleotide microarray probe
Utility spot pricing, California
Schweppe, Fred C.
1982-01-01T23:59:59.000Z
The objective of the present spot pricing study carried out for SCE and PG&E is to develop the concepts which wculd lead to an experimental design for spot pricing in the two utilities. The report suggests a set of experiments ...
Rea, H. E.
1958-01-01T23:59:59.000Z
use of cultural methods supplemented by spot-spraying. Herbicidal oils and water solutions of sodium dalapon, sodium TCA and maleic hydrazide are some of the sprays used for spot-treating Johnsongrass. Oils are commonly applied to the crown. Water...-spraying is an effective and convenient method Ior killing Johnsongrass sprouts and seedlings that other- ~,\\iqe are neglected in row crops. Herbicidal oils ancl t\\atcr solutions of sodium dalapon, sodium TCA and 111,11eic hydrazide are some of the sprays used...
MAIN APPLICATIONS Spot welding
De Luca, Alessandro
IRB 6400 MAIN APPLICATIONS Spot welding Press tending Material handling Machine tending Palletizing N Poke welding All IRB 6400R-versions have Foundry Plus protection. For details, see under manipulator 6400PE 1600 kg Others 2060 - 2390 kg ENVIRONMENT Ambient temperature Manipulator 5 50°C Relative
Elliott, Fred C.; Norris, M. J.; Rea, H. E.
1955-01-01T23:59:59.000Z
I TEXAS AGRICULTURAL EXTENSIO-N SERVICE G. G. Gibson, Director, College Station, Texas [Blank Page in Original Bulletin] I the bast I ir used the low I . .. 1 the fol or mort , needed SPOT-OILING JOHNSONGRASS H. E. Rea, M. J. Norris..., and Fred C. Elliott* Texas A. & M. College System ~HNSONGRASS CAN BE killed to the i ground by the application of 1 / 3 teaspoonful of a herbicidal oil to the crown of each stem. Eradication of established Johnsongrass can be obtained in a single...
Dermoscopy of black-spot poison ivy
Rader, Ryan K; Mu, Ruipu; Shi, Honglan; Stoecker, William V; Hinton, Kristen A
2012-01-01T23:59:59.000Z
CT, Bean AS. Black-spot poison ivy: A rare phenomenon. J AmJG, Lucky AW. Black spot poison ivy: A report of 5 cases andis unique for black-spot poison ivy. The UFLC-MS/MS urushiol
Utility spot pricing study : Wisconsin
Caramanis, Michael C.
1982-01-01T23:59:59.000Z
Spot pricing covers a range of electric utility pricing structures which relate the marginal costs of electric generation to the prices seen by utility customers. At the shortest time frames prices change every five ...
Traps, Patches, Spots, and Stripes: Localized Solutions to Diffusive and
Ward, Michael Jeffrey
-Replicating Spot Behavior: I Experimental evidence of spot-splitting The Ferrocyanide-iodate-sulphite reaction
Why sulfonamides are contraindicated in Rocky Mountain spotted fever
Ren, Vicky; Hsu, Sylvia
2014-01-01T23:59:59.000Z
and mortality in cases of Rocky Mountain spotted fever. ClinNH. Experimental Rocky Mountain spotted fever and endemicRR. Experimental Rocky Mountain spotted fever: Results of
Hot and Cold Spots in the First plus Second Year COBE/DMR Maps
Laura Cayon; George Smoot
1995-04-20T23:59:59.000Z
Density perturbations at the decoupling epoch produce angular fluctuations in the temperature of the Cosmic Microwave Background (CMB) radiation that may appear as hot and cold spots. Observational data of the CMB includes instrumental noise in addition to the cosmological signal. One would like to determine which of the observed spots are produced by the noise and which correspond to signal. In this work we first present a statistical analysis of the first plus second year COBE/DMR map at 53 GHz that reveals the presence of cosmological signal in the data. The analysis is based on Harrison-Zeldovich Monte Carlo realizations and utilizes a generalized $\\chi^2$ statistic. The method is applied to the number of spots and the fraction of the total area that appear above/below a certain value of the dispersion of the noise, including and excluding the quadrupole, giving $Q_{rms-PS}=15^{+3}_{-6}$, $18^{+5}_{-7} \\mu K$ and $Q_{rms-PS}=18^{+3}_{-4}$, $21\\pm6 \\mu K$, at the $95\\%$ confidence level, respectively. The data taken by the COBE/DMR experiment during the first two years at three different frequencies (31, 53 and 90 GHz) are used to determine which of the spots observed at 53 GHz appear simultaneously in the other two channels. The significance of those spots is determined by comparison of their area and signal-to-noise with noise Monte Carlo simulations. We point out two cold spots and one hot spot at positions $(l,b)\\approx (-99^{\\circ},57^{\\circ}),(-21^{\\circ},-45^{\\circ}), (-81^{\\circ},-33^{\\circ})$ respectively, at the $95 \\%$ confidence level.
Oscillating Reaction-Diffusion Spots Aric Hagberg
Hagberg, Aric
, oscillating circular spots have also been found in the Ferrocyanide-Iodate-Sulfite reaction [4]. One kind
Regions for Select Spot Prices
Gasoline and Diesel Fuel Update (EIA)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23 362 334 318 706 802 1979-2013October 3, 2002 (next releaseCapacity Report JuneRegions for Select Spot
Resistance Spot Welding of Galvanized Steel: Part II. Mechanisms of Spot Weld Nugget Formation
Eagar, Thomas W.
( l Resistance Spot Welding of Galvanized Steel: Part II. Mechanisms of Spot Weld Nugget Formation S. A. GEDEON and T. W. EAGAR Dynamic inspection monitoring of the weld current, voltage, resistance of material variations and weld process parameter modifications on resistance spot welding of coated
HotSpot Software Configuration Management Plan
Walker, H; Homann, S G
2009-03-12T23:59:59.000Z
This Software Configuration Management Plan (SCMP) describes the software configuration management procedures used to ensure that the HotSpot dispersion model meets the requirements of its user base, which includes: (1) Users of the PC version of HotSpot for consequence assessment, hazard assessment and safety analysis calculations; and (2) Users of the NARAC Web and iClient software tools, which allow users to run HotSpot for consequence assessment modeling These users and sponsors of the HotSpot software and the organizations they represent constitute the intended audience for this document. This plan is intended to meet Critical Recommendations 1 and 3 from the Software Evaluation of HotSpot and DOE Safety Software Toolbox Recommendation for inclusion of HotSpot in the Department of Energy (DOE) Safety Software Toolbox. HotSpot software is maintained for the Department of Energy Office of Emergency Operations by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL). An overview of HotSpot and NARAC are provided.
Friction Stir Spot Welding of Advanced High Strength Steels ...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
does not contain any proprietary or confidential information Friction Stir Spot Welding of Advanced High Strength Steels (AHSS) (13056 ORNL, 13055 PNNL) Friction Stir Spot...
CMB Cold Spot from Inflationary Feature Scattering
Wang, Yi
2015-01-01T23:59:59.000Z
We propose a "feature-scattering" mechanism to explain the cosmic microwave background cold spot seen from {\\it WMAP} and {\\it Planck} maps. If there are hidden features in the potential of multi-field inflation, the inflationary trajectory can be scattered by such features. The scattering is controlled by the amount of isocurvature fluctuations, and thus can be considered as a mechanism to convert isocurvature fluctuations into curvature fluctuations. This mechanism predicts localized cold spots (instead of hot ones) on the CMB. In addition, it may also bridge a connection between the cold spot and a dip on the CMB power spectrum at $\\ell \\sim 20$.
Measuring microfocus focal spots using digital radiography
Fry, David A [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
Measurement of microfocus spot size can be important for several reasons: (1) Quality assurance during manufacture of microfocus tubes; (2) Tracking performance and stability of microfocus tubes; (3) Determining magnification (especially important for digital radiography where the native spatial resolution of the digital system is not adequate for the application); (4) Knowledge of unsharpness from the focal spot alone. The European Standard EN 12543-5 is based on a simple geometrical method of calculating focal spot size from unsharpness of high magnification film radiographs. When determining microfocus focal spot dimensions using unsharpness measurements both signal-to-noise (SNR) and magnification can be important. There is a maximum accuracy that is a function of SNR and therefore an optimal magnification. Greater than optimal magnification can be used but it will not increase accuracy.
2015 ORNL Audio Spots | ornl.gov
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
5 2015 ORNL Audio Spots 1-5 of 5 Results ORNL kicks off 2015 United Way campaign with agency fair ORNL kicks off 2015 United Way campaign with agency fair OAK RIDGE, Tenn., July...
The Stability and Dynamics of Localized Spot Patterns in the 2-D Gray-Scott Model
Ward, Michael Jeffrey
-Replicating Spots: Overview I Experimental evidence of spot-splitting The Ferrocyanide-iodate-sulphite reaction
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (Million Cubic Feet)setsManagementProton ChannelMedia3/2012Quantifying the AerosolQuantum Monte
Marcus, Ryan C. [Los Alamos National Laboratory
2012-07-25T23:59:59.000Z
MCMini is a proof of concept that demonstrates the possibility for Monte Carlo neutron transport using OpenCL with a focus on performance. This implementation, written in C, shows that tracing particles and calculating reactions on a 3D mesh can be done in a highly scalable fashion. These results demonstrate a potential path forward for MCNP or other Monte Carlo codes.
Quantum Gibbs ensemble Monte Carlo
Fantoni, Riccardo, E-mail: rfantoni@ts.infn.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Calle Larga S. Marta DD2137, I-30123 Venezia (Italy); Moroni, Saverio, E-mail: moroni@democritos.it [DEMOCRITOS National Simulation Center, Istituto Officina dei Materiali del CNR and SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy)
2014-09-21T23:59:59.000Z
We present a path integral Monte Carlo method which is the full quantum analogue of the Gibbs ensemble Monte Carlo method of Panagiotopoulos to study the gas-liquid coexistence line of a classical fluid. Unlike previous extensions of Gibbs ensemble Monte Carlo to include quantum effects, our scheme is viable even for systems with strong quantum delocalization in the degenerate regime of temperature. This is demonstrated by an illustrative application to the gas-superfluid transition of {sup 4}He in two dimensions.
TRANSIENT THERMAL BEHAVIOR IN RESISTANCE SPOT WELDING
Eagar, Thomas W.
temperature response during resistance spot welding was measured and discussed with various process parameters that the measurement of temperature profiles developed during the welding process is very important in this respect composition on galvanized steel, the temperature distribution during welding was monitored in a one
THE OCCURRENCE OF SPOT, LEIOSTOMUS XANTHURUS, AND
of postlarval spot and Atlantic croaker within the Cape Fear River estuary, N.C., above a steam electric power, National Marine Fisheries Service, NOAA, Beaufort, NC 28516. 'Brunswick Steam Electric Plant, Cape Fear. 'Brunswick Steam Electric Plant, Cape Fear Studies. Ocean larval fish, November 1976-1978. Environmental
Measuring microfocal spots using digital radiography
Fry, David A [Los Alamos National Laboratory; Ewert, Uwe [BAM
2009-01-01T23:59:59.000Z
Measurement of microfocus spot size can be important for several reasons: (1) Quality assurance during manufacture of microfocus tubes; (2) Tracking performance and stability of microfocus tubes; (3) Determining magnification is especially important for digital radiography where the native spatial resolution of the digital system is not adequate for the application; and (4) Knowledge of unsharpness from the focal spot alone. The European Standard EN 12543-5 is based on a simple geometrical method of calculating focal spot size from unsharpness of high magnification film radiographs. The following equations are used for the focal spot size measurement: By similar triangles the following equations are presupposed: f/a = U/b and M = (a+b)/a. These equations can be combined to yield the well known expression: U = f(M - 1). Solving for f, f = U/(M-1). Therefore, the focal spot size, f, can be calculated by measuring the radiographic unsharpness and magnification of a known object. This is the basis for these tests. The European standard actually uses one-half of the unsharpness (which are then added together) from both sides of the object to avoid additional unsharpness contributions due to edge transmission unsharpness of the round test object (the outside of the object is measured). So the equation becomes f = (1/2 U{sub 1} + 1/2 U{sub 2})/(M-1). In practice 1/2 U is measured from the 50% to the 90% signal points on the transition profile from ''black'' to ''white,'' (positive image) or attenuated to unattenuated portion of the image. The 50% to 90% points are chosen as a best fit to an assumed Gaussian radiation distribution from the focal spot and to avoid edge transmission effects. 1/2 U{sub 1} + 1/2 U{sub 2} corresponds about to the full width at half height of a Gaussian focal spot. A highly absorbing material (Tungsten, Tungsten Alloy, or Platinum) is used for the object. Either wires or a sphere are used as the object to eliminate alignment issues. One possibility is to use the wires in the ASTM E2002 unsharpness gage and take two orthogonal images. The signal levels in the image need to be linear with radiation exposure and so may need conversion if a nonlinear detector is used to acquire the image.
Friction Stir Spot Welding of Advanced High Strength Steels ...
Stir Spot Welding of Advanced High Strength Steels (AHSS) Friction Stir Spot Welding of Advanced High Strength Steels (AHSS) Presentation from the U.S. DOE Office of Vehicle...
Improving Diesel Engine Sweet-spot Efficiency and Adapting it...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Diesel Engine Sweet-spot Efficiency and Adapting it to Improve Duty-cycle MPG - plus Increasing Propulsion and Reducing Cost Improving Diesel Engine Sweet-spot Efficiency and...
Prediction of cooling rate and microstructure in laser spot welds
Cambridge, University of
during laser spot welding of low alloy steel. A transient heat transfer model that takes into account
Master thesis Spot Weldability of TRIP Steel with
Cambridge, University of
. Recent research on TRIP-assisted steel alloy with relatively high carbon and aluminium concentrationMaster thesis Spot Weldability of TRIP Steel with High Carbon, High Aluminium Content Jung, Geunsu 2011 #12; , TRIP Spot Weldability of TRIP Steel with High Carbon, High Aluminium Content #12;Spot
Robotic spotting of cDNA and oligonucleotide microarrays
Kreil, David
Robotic spotting of cDNA and oligonucleotide microarrays Richard P. Auburn1 , David P. Kreil1 recent techno- logical advances with a focus on spotted arrays. Robotic spotting still poses numerous popular one, micro- arrays for gene expression analysis. Microarrays can be manufactured using robotic
Population Assessment of the Northern Spotted Owl in
Owl Management Plan. Within our survey areas, Spotted Owl occupancy declined by 49% between 1992.C. Conservation Foundation Carla B. Lenihan, Ministry of Sustainable Resource Management #12;Population Assessment of the Northern Spotted Owl in British Columbia 1992-2001 Page 1 Abstract In 1997, the Spotted Owl Management Plan
Berkeley Lab's SPOT Suite Transforms Beamline Science
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports(Journal Article) |govInstrumentsmfrirt DocumentationSitesWeather Outreach HomeDeKalbAnnualAssemblyBasicsSecurity1Berkeley20/10GuestSPOT Suite
ClearSpot Energy | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaP aCentrotherm Photovoltaics AG JumpClean and Renewable Energy Home > CleanCleantechClearClearSpot
Is Monte Carlo embarrassingly parallel?
Hoogenboom, J. E. [Delft Univ. of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Delft Nuclear Consultancy, IJsselzoom 2, 2902 LB Capelle aan den IJssel (Netherlands)
2012-07-01T23:59:59.000Z
Monte Carlo is often stated as being embarrassingly parallel. However, running a Monte Carlo calculation, especially a reactor criticality calculation, in parallel using tens of processors shows a serious limitation in speedup and the execution time may even increase beyond a certain number of processors. In this paper the main causes of the loss of efficiency when using many processors are analyzed using a simple Monte Carlo program for criticality. The basic mechanism for parallel execution is MPI. One of the bottlenecks turn out to be the rendez-vous points in the parallel calculation used for synchronization and exchange of data between processors. This happens at least at the end of each cycle for fission source generation in order to collect the full fission source distribution for the next cycle and to estimate the effective multiplication factor, which is not only part of the requested results, but also input to the next cycle for population control. Basic improvements to overcome this limitation are suggested and tested. Also other time losses in the parallel calculation are identified. Moreover, the threading mechanism, which allows the parallel execution of tasks based on shared memory using OpenMP, is analyzed in detail. Recommendations are given to get the maximum efficiency out of a parallel Monte Carlo calculation. (authors)
An inequality for potentials and the “hot–spots” conjecture
2003-06-04T23:59:59.000Z
inequality, by the conformal invariance of Brownian motion, implies a result of Pascu [13] on “hot–spots” for certain symmetric convex domains. ?Supported in ...
Jefferson Lab Medical Imager Spots Breast Cancer | Jefferson...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Eric Rosen, Duke University Medical Center Jefferson Lab Medical Imager Spots Breast Cancer March 3, 2005 Newport News, VA - A study published in the February issue of the...
Friction Stir Spot Welding of Advanced High Strength Steels II...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Steels II Friction Stir Spot Welding of Advanced High Strength Steels II 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer...
Zimmerman, G.B.
1997-06-24T23:59:59.000Z
Monte Carlo methods appropriate to simulate the transport of x-rays, neutrons, ion and electrons in Inertial Confinement Fusion targets are described and analyzed. The Implicit Monte Carlo method of x-ray transport handles symmetry within indirect drive ICF hohlraums well, but can be improved 50X in efficiency by angular biasing the x-rays towards the fuel capsule. Accurate simulation of thermonuclear burns nd burn diagnostics involves detailed particle source spectra, charged particle ranges, inflight reaction kinematics, corrections for bulk and thermal Doppler effects and variance reduction to obtain adequate statistics for rare events. It is found that the effects of angular Coulomb scattering must be included in models of charged particle transport through heterogeneous materials.
Modified Fresnel zone plates that produce sharp Gaussian focal spots
Jahns, Jürgen
Modified Fresnel zone plates that produce sharp Gaussian focal spots Qing Cao and Ju¨rgen Jahns Fresnel zone plate that can produce an approximate Gaussian focal spot is proposed for the focusing of 7.7 nm can be produced by a modified Fresnel zone plate with a minimum structure size of 30 nm
Modelling spot and forward prices for energy companies
Bhulai, Sandjai
Modelling spot and forward prices for energy companies Dafydd Steele MSc Stochastics and Financial forward and spot prices for energy com- panies. The two main ways of modelling power prices are stochastic Mathematics dafydd.steele@edf-energy.com August 5, 2010 #12;Abstract The focus of this thesis is on modelling
Cinematography of Resistance Spot Welding of Galvanized Steel Sheet
Eagar, Thomas W.
Cinematography of Resistance Spot Welding of Galvanized Steel Sheet Preweld and postweld current modifications on the resistance spot welding of galvanized steel sheet ·are analyzed using high phenomena through· out the weld process are discussed. In addition. the duration of current modifi· cation
POWER '99 Conference 1 Stochastic Models of Electricity Spot Price
California at Berkeley. University of
risks in wholesale and retail markets. · Asset valuation, project selection and financing. Divestiture markets. POWER '99 Conference 4 Application (1): Derivative Pricing Examples: Call Option & Spark Spread electricity spot price spot price Power Marketer Transmission cost? COB: PCOB max( , )S K ST PV loss T COB
Statistical Modeling of Spot Instance Prices in Public Cloud Environments
Buyya, Rajkumar
Statistical Modeling of Spot Instance Prices in Public Cloud Environments Bahman Javadi, Ruppa K resources has introduced many trade-offs between price, per- formance and recently reliability. Amazon's Spot Instances (SIs) create a competitive bidding option for the public Cloud users at lower prices
Tenneco upgrades natural gasoline
O'Gorman, E.K.
1986-08-01T23:59:59.000Z
Tenneco Oil Co. recently completed a natural gasoline upgrading project at its LaPorte, Tex., facility. The project was started in October 1985. The purpose was to fractionate natural gasoline and isomerize the n-pentane component. Three factors made this a particularly attractive project for the LaPorte complex: 1. The phase down of lead in gasoline made further processing of natural gasoline desirable. 2. Idle equipment and trained personnel were available at the plant as a result of a switch of Tenneco's natural gas liquids (NGL) fractionation to its Mont Belvieu, Tex., facility. 3. The plant interconnects with Houston's local markets. It has pipelines to Mont Belvieu, Texas City, and plants along the Houston Ship Channel, as well as truck, tank car, and barge-loading facilities. Here are the details on the operation of the facilities, the changes which were required to enable the plant to operate successfully, and how this conversion was completed in a timely fashion.
Rocky Mountain Spotted Fever in a patient treated with anti-TNF-alpha inhibitors
Mays, Rana M; Gordon, Rachel A; Durham, K Celeste; LaPolla, Whitney J; Tyring, Stephen K
2013-01-01T23:59:59.000Z
SJ, Paddock CD. Rocky Mountain spotted fever: a clinician'sand Prevention. Rocky Mountain Spotted Fever . http://Demma LJ, et al. Rocky mountain spotted fever in the United
Monte Carlo Methods in Quantum Field Theory
I. Montvay
2007-05-30T23:59:59.000Z
In these lecture notes some applications of Monte Carlo integration methods in Quantum Field Theory - in particular in Quantum Chromodynamics - are introduced and discussed.
Feast or famine: 1992 spot market review
Not Available
1993-01-01T23:59:59.000Z
There was nothing temperate about the uranium spot market in 1992. It was a year of extremes. Demand took off at a brisk pace early in the year as utilities, enticed by low U3O8 prices and interest rates, stepped up their discretionary purchases. With the NUKEM price range sinking to an all-time low of US$6.75-7.70 in November 1991, utilities reckoned that prices had bottomed out and decided to buy and hold material. Indeed, the upper end of NUKEM's range remained below $8.00 per lb for much of the first half of 1992. The main cause of low prices was the flood of imports from the crumbling Soviet Union and its successor, the Commonwealth of Independent States [CIS]. The CIS republics quickly embraced a free-market philosophy to boost their faltering economies, and several hoped to use uranium as a source of badly-needed hard currency. But they were about to get a harsh introduction to capitalism. It came in the form of government intervention, in both the US and Europe. In May, the US Department of Commerce made its preliminary determination that the uranium-producing republics of the CIS were selling material in the US at less than fair market value. The antidumping case was eventually settled in October when the CIS republics [Russia, Ukraine, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan] signed suspension agreements subjecting CIS origin uranium to price and quantity quotas in the US.
Finite Cosmology and a CMB Cold Spot
Adler, R.J.; /Stanford U., HEPL; Bjorken, J.D.; /SLAC; Overduin, J.M.; /Stanford U., HEPL
2006-03-20T23:59:59.000Z
The standard cosmological model posits a spatially flat universe of infinite extent. However, no observation, even in principle, could verify that the matter extends to infinity. In this work we model the universe as a finite spherical ball of dust and dark energy, and obtain a lower limit estimate of its mass and present size: the mass is at least 5 x 10{sup 23}M{sub {circle_dot}} and the present radius is at least 50 Gly. If we are not too far from the dust-ball edge we might expect to see a cold spot in the cosmic microwave background, and there might be suppression of the low multipoles in the angular power spectrum. Thus the model may be testable, at least in principle. We also obtain and discuss the geometry exterior to the dust ball; it is Schwarzschild-de Sitter with a naked singularity, and provides an interesting picture of cosmogenesis. Finally we briefly sketch how radiation and inflation eras may be incorporated into the model.
Wall and laser spot motion in cylindrical hohlraums
Huser, G.; Courtois, C.; Monteil, M.-C. [CEA, DAM, DIF, F-91297 Arpajon (France)
2009-03-15T23:59:59.000Z
Wall and laser spot motion measurements in empty, propane-filled and plastic (CH)-lined gold coated cylindrical hohlraums were performed on the Omega laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. Wall motion was measured using axial two-dimensional (2D) x-ray imaging and laser spot motion was perpendicularly observed through a thinned wall using streaked hard x-ray imaging. Experimental results and 2D hydrodynamic simulations show that while empty targets exhibit on-axis plasma collision, CH-lined and propane-filled targets inhibit wall expansion, corroborated with perpendicular streaked imaging showing a slower motion of laser spots.
High-power-density spot cooling using bulk thermoelectrics
Zhang, Y; Shakouri, A; Zeng, G H
2004-01-01T23:59:59.000Z
model, the cooling power densities of the devices can alsothe cooling power densities 2–24 times. Experimentally, the14 4 OCTOBER 2004 High-power-density spot cooling using bulk
Spot Convenience Yield Models for Energy Michael Ludkovski
Ludkovski, Mike
. This is not true for some commodities, such as electricity. Even for mature markets like crude oil where spot on a continuously compounded basis. Intuitively, the convenience yield corresponds to dividend yield for stocks
Characterization of Resistance to Black Spot Disease of Rosa Spp.
Dong, Qianni
2014-12-01T23:59:59.000Z
(WPI) approach, indicated that these were well correlated. Thus either method could be used to assess the resistance of the plants to the BSD. Fifteen diploid hybrid populations from 10 parents segregating for black spot partial (horizontal) resistance...
A 9 Monte Carlo Simulations Michael Bachmann
Bachmann, Michael
generally called "thermal fluctua- tions") or "lose" energy by friction effects (dissipation). The total Reweighting methods 9 3.1 Single-histogram reweighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-ensemble Monte Carlo methods 12 4.1 Replica-exchange Monte Carlo method (parallel tempering
Imaging of semiconductors using a flying laser spot scanning system
Richardson, Thomas William
1982-01-01T23:59:59.000Z
IMAGING OF SEMICONDUCTORS USING A FLYING LASER SPOT SCANNING SYSTEM A Thesis by THOMAS WILLIAM RICHARDSON Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... December 1982 Major Subject: Electrical Engineering IMAGING OF SEMICONDUCTORS USING A PLYING LASER SPOT SCANNING SYSTEM A Thesis by THOMAS WILLIAM RICHARDSON Approved as to style and content by: D. L. Parker (Chairman) (EE) W. A. Porter (Member...
Applications of FLUKA Monte Carlo Code for Nuclear and Accelerator...
Office of Scientific and Technical Information (OSTI)
Journal Article: Applications of FLUKA Monte Carlo Code for Nuclear and Accelerator Physics Citation Details In-Document Search Title: Applications of FLUKA Monte Carlo Code for...
Monte Carlo simulation in systems biology
Schellenberger, Jan
2010-01-01T23:59:59.000Z
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
THE BEGINNING of the MONTE CARLO METHOD
. For a whole host of 125 #12;Monte Carlo reasons, he had become seriously inter- ested in the thermonuclear a preliminary computational model of a thermonuclear reaction for the ENIAC. He felt he could convince
Multiple quadrature by Monte Carlo techniques
Voss, John Dietrich
1966-01-01T23:59:59.000Z
of a multiple integral ordinarily hopeless to attempt by 1 classical methods. " In this paper the Monte Carlo Method of numerical quadrature is used to integrate some functions that are extremely difficult and tedious to integrate by any other known... and the table of known values can be extended. The method developed here may also be used to evaluate the distribution at any desired values of the parameters . C HAP TER II THEORETICAL CONSIDERATIONS Hammersley has said: "Every Monte Carlo computation...
LASER FLUOROSENSOR FOR OIL SPOT DETECTION R. Karpicza
Oldenburg, Carl von Ossietzky Universität
LASER FLUOROSENSOR FOR OIL SPOT DETECTION R. Karpicza , A. Dementjeva , Z. Kuprionisb , S of Oldenburg, Institute of Physics, D-26111 Oldenburg, Germany E-mail: vidgulb@ktl.mii.lt Oil and water to the fourth and third harmonics of a Nd:YAG laser. The oil spill detection fluorosensor designed for onshore
Quantifying intrapopulation variability in stable isotope data for Spotted Seatrout
111 Quantifying intrapopulation variability in stable isotope data for Spotted Seatrout (Cynoscion of the National Marine Fisheries Service, NOAA. Abstract--Stable isotope (SI) values of carbon (13C) and nitrogen patterns of enrichment in fish caught from coastal to off- shore sites and as a function of fish size
On super resolved spots in the near-field Proefschrift
as function of the laser power. Below the red line tagged with squares, super resolved spots are observed. #12.3 Current optical data storage market . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3.1 Video Transform approach . . . . . . . . . . . . . . . . . . . . . . . 10 2.3 Scalar threshold model for Super
SPOT PRICING FRAMEWORK FOR LOSS GUARANTEED INTERNET SERVICE CONTRACTS
Kalyanaraman, Shivkumar
. In a two-component approach to pricing, a nonlinear pricing scheme is used for cost recovery and a utility for cost recovery, and (ii) an options-based approach to price the risk of deviations in the loss based QoSPOT PRICING FRAMEWORK FOR LOSS GUARANTEED INTERNET SERVICE CONTRACTS Aparna Gupta Decision
A NONGAUSSIAN ORNSTEINUHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND
Kallsen, Jan
concepts from the HeathJarrowMorton theory for interest rates to electricity markets to modelA NONGAUSSIAN ORNSTEINUHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND DERIVATIVES for analytical pricing of electricity forward and futures contracts. Electricity forward and futures contracts
Raman Scattering from 1,3-Propanedithiol at a Hot Spot: Theory...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
from 1,3-Propanedithiol at a Hot Spot: Theory Meets Experiment. Raman Scattering from 1,3-Propanedithiol at a Hot Spot: Theory Meets Experiment. Abstract: We compute the Raman...
Fractured reservoir evaluation using Monte Carlo techniques
Sears, G.F.; Phillips, N.V.
1987-01-01T23:59:59.000Z
Pro forma cash-flow analysis of petroleum ventures usually is considered as a deterministic model. In the last 10 years, Monte Carlo analysis has allowed the introduction of probability distributions of input variables in place of single-valued functions. Reserve determination and rate scheduling in these current Monte Carlo techniques have relied on the volumetric formula, which works well in nonfractured reservoirs. Recent massive drilling in fractured reservoirs has rendered this approach unusable. This paper develops a variation of the Arps rate-cumulative equation as a basic model for the determination of the distribution of original reserves and the decline rates. Continuation of the Monte Carlo technique into net present value analysis and internal rate of return (IRR) is also developed.
Tian, Zhen; Folkerts, Michael; Shi, Feng; Jiang, Steve B; Jia, Xun
2015-01-01T23:59:59.000Z
Monte Carlo (MC) simulation is considered as the most accurate method for radiation dose calculations. Accuracy of a source model for a linear accelerator is critical for the overall dose calculation accuracy. In this paper, we presented an analytical source model that we recently developed for GPU-based MC dose calculations. A key concept called phase-space-ring (PSR) was proposed. It contained a group of particles that are of the same type and close in energy and radial distance to the center of the phase-space plane. The model parameterized probability densities of particle location, direction and energy for each primary photon PSR, scattered photon PSR and electron PSR. For a primary photon PSRs, the particle direction is assumed to be from the beam spot. A finite spot size is modeled with a 2D Gaussian distribution. For a scattered photon PSR, multiple Gaussian components were used to model the particle direction. The direction distribution of an electron PSRs was also modeled as a 2D Gaussian distributi...
OPTICAL SPECTROSCOPY OF CANDIDATE HOT SPOTS IN RADIO GALAXIES AND QUASARS
Martini, Paul
of a few hot spots (Simkin 1978), surveys by Saslaw, Tyson, & Crane (1978; STC) and Crane, Tyson, & Saslaw
Quantum Mechanical Single Molecule Partition Function from Path Integral Monte Carlo Simulations
Chempath, Shaji; Bell, Alexis T.; Predescu, Cristian
2008-01-01T23:59:59.000Z
calculated from path integral Monte Carlo(PIMC) and harmoniccalculated from path integral Monte Carlo (PIMC) andFunction from Path Integral Monte Carlo Simulations Shaji
Delivery and Hedging Delivery ties the futures price to the spot price.
Lyuu, Yuh-Dauh
Delivery and Hedging Â· Delivery ties the futures price to the spot price. Â· On the delivery date, the settlement price of the futures contract is determined by the spot price. Â· Hence, when the delivery period is reached, the futures price should be very close to the spot price. Â· Changes in futures prices usually
Noble, William Stafford
, such as when- ever it is inconvenient, unsafe, or impossible for the user to enter a search query using and the utterance being searched is beneficial for spoken keyword spotting. In this paper, we introduce several im- prove the performance of spoken keyword spotting. Index Terms-- Spoken keyword spotting, lattice
De Vany, Arthur; Walls, W. David
1992-01-01T23:59:59.000Z
Experimental Research on Deregulation, natural Gas Pipelineto MarketsFail: Pipeline Deregulation,Spot Markets,and theto Markets Fall: Deregulation, Spot Markets, And the
The Proton Therapy Nozzles at Samsung Medical Center: A Monte Carlo Simulation Study using TOPAS
Chung, Kwangzoo; Kim, Dae-Hyun; Ahn, Sunghwan; Han, Youngyih
2015-01-01T23:59:59.000Z
To expedite the commissioning process of the proton therapy system at Samsung Medical Center (SMC), we have developed a Monte Carlo simulation model of the proton therapy nozzles using TOPAS. At SMC proton therapy center, we have two gantry rooms with different types of nozzles; a multi-purpose nozzle and a dedicated scanning nozzle. Each nozzle has been modeled in detail following the geometry information provided by the manufacturer, Sumitomo Heavy Industries, Ltd. For this purpose, novel features of TOPAS, such as the time feature or the ridge filter class, have been used. And the appropriate physics models for proton nozzle simulation were defined. Dosimetric properties, like percent depth dose curve, spread-out Bragg peak (SOBP), beam spot size, have been simulated and verified against measured beam data. Beyond the Monte Carlo nozzle modeling, we have developed an interface between TOPAS and the treatment planning system (TPS), RayStation. An exported RT plan data from the TPS has been interpreted by th...
Magnetic fields, spots and weather in chemically peculiar stars
O. Kochukhov
2007-11-30T23:59:59.000Z
New observational techniques and sophisticated modelling methods has led to dramatic breakthroughs in our understanding of the interplay between the surface magnetism, atomic diffusion and atmospheric dynamics in chemically peculiar stars. Magnetic Doppler images, constructed using spectropolarimetric observations of Ap stars in all four Stokes parameters, reveal the presence of small-scale field topologies. Abundance Doppler mapping has been perfected to the level where distributions of many different chemical elements can be deduced self-consistently for one star. The inferred chemical spot structures are diverse and do not always trace underlying magnetic field geometry. Moreover, horizontal chemical inhomogeneities are discovered in non-magnetic CP stars and evolving chemical spots are observed for the first time in the bright mercury-manganese star alpha And. These results show that in addition to magnetic fields, another important non-magnetic structure formation mechanism acts in CP stars.
Multi-spot ignition in type Ia supernova models
Roepke, F K; Niemeyer, J C; Woosley, S E
2005-01-01T23:59:59.000Z
We present a systematic survey of the capabilities of type Ia supernova explosion models starting from a number of flame seeds distributed around the center of the white dwarf star. To this end we greatly improved the resolution of the numerical simulations in the initial stages. This novel numerical approach facilitates a detailed study of multi-spot ignition scenarios with up to hundreds of ignition sparks. Two-dimensional simulations are shown to be inappropriate to study the effects of initial flame configurations. Based on a set of three-dimensional models, we conclude that multi-spot ignition scenarios may improve type Ia supernova models towards better agreement with observations. The achievable effect reaches a maximum at a limited number of flame ignition kernels as shown by the numerical models and corroborated by a simple dimensional analysis.
Multi-spot ignition in type Ia supernova models
F. K. Roepke; W. Hillebrandt; J. C. Niemeyer; S. E. Woosley
2005-10-17T23:59:59.000Z
We present a systematic survey of the capabilities of type Ia supernova explosion models starting from a number of flame seeds distributed around the center of the white dwarf star. To this end we greatly improved the resolution of the numerical simulations in the initial stages. This novel numerical approach facilitates a detailed study of multi-spot ignition scenarios with up to hundreds of ignition sparks. Two-dimensional simulations are shown to be inappropriate to study the effects of initial flame configurations. Based on a set of three-dimensional models, we conclude that multi-spot ignition scenarios may improve type Ia supernova models towards better agreement with observations. The achievable effect reaches a maximum at a limited number of flame ignition kernels as shown by the numerical models and corroborated by a simple dimensional analysis.
Monte Carlo Tools for Jet Quenching
Korinna Zapp
2011-09-07T23:59:59.000Z
A thorough understanding of jet quenching on the basis of multi-particle final states and jet observables requires new theoretical tools. This talk summarises the status and propects of the theoretical description of jet quenching in terms of Monte Carlo generators.
Monte Carlo event reconstruction implemented with artificial neural networks
Tolley, Emma Elizabeth
2011-01-01T23:59:59.000Z
I implemented event reconstruction of a Monte Carlo simulation using neural networks. The OLYMPUS Collaboration is using a Monte Carlo simulation of the OLYMPUS particle detector to evaluate systematics and reconstruct ...
Imaging of semiconductors using a flying laser spot scanning system
Richardson, Thomas William
1982-01-01T23:59:59.000Z
in silicon p-n junctions was a direct result of this research. Verification of the experimental findings include analysis using other characterization techniques such as X-ray topo- graphy, electrical testing and preferential chemical etching... Image (I. R. Radiation) . . 22 Flying Spot Scanner Photo Image (Visible Radiation) . 23 15 Photo Image Showing Crystal Defects 24 16 Sirtl Etch Photomicrograph of Lattice Crystal Defects 25 17 Photo Image Showing Laser Induced Lifetime Changes 26...
Matrix phased array (MPA) imaging technology for resistance spot welds
Na, Jeong K.; Gleeson, Sean T. [Edison Welding Institute, 1250 Arthur E. Adams Drive, Columbus, OH 43221 (United States)
2014-02-18T23:59:59.000Z
A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.
John von Neumann Institute for Computing Monte Carlo Protein Folding
Hsu, Hsiao-Ping
John von Neumann Institute for Computing Monte Carlo Protein Folding: Simulations of Met://www.fz-juelich.de/nic-series/volume20 #12;#12;Monte Carlo Protein Folding: Simulations of Met-Enkephalin with Solvent-Accessible Area difficulties in applying Monte Carlo methods to protein folding. The solvent-accessible area method, a popular
Deterministic Simulation for Risk Management QuasiMonte Carlo beats
Papageorgiou, Anargyros
1 Deterministic Simulation for Risk Management QuasiMonte Carlo beats Monte Carlo for Value are widely used in pricing and risk management of complex financial instruments. Recently, quasiMonte Carlo and accuracy. In this paper we address the application of these deterministic methods to risk management. Our
Deterministic Simulation for Risk Management Quasi-Monte Carlo beats
Papageorgiou, Anargyros
1 Deterministic Simulation for Risk Management Quasi-Monte Carlo beats Monte Carlo for Value are widely used in pricing and risk management of complex financial instruments. Recently, quasi-Monte Carlo and accuracy. In this paper we address the application of these deterministic methods to risk management. Our
Peters, Richard
Top Spot is an intelligent advertising product that targets your most suitable listings to the right people by suburb and price. Top Spot listings appear at the top of the search results page estate agency both before and after signing up to Top Spot. 72% MORE VIEWS^ Advertising with Top Spot
Random number stride in Monte Carlo calculations
Hendricks, J.S.
1990-01-01T23:59:59.000Z
Monte Carlo radiation transport codes use a sequence of pseudorandom numbers to sample from probability distributions. A common practice is to start each source particle a predetermined number of random numbers up the pseudorandom number sequence. This number of random numbers skipped between each source particles the random number stride, S. Consequently, the jth source particle always starts with the j{center dot}Sth random number providing correlated sampling'' between similar calculations. A new machine-portable random number generator has been written for the Monte Carlo radiation transport code MCNP providing user's control of the random number stride. First the new MCNP random number generator algorithm will be described and then the effects of varying the stride will be presented. 2 refs., 1 fig.
Spot Prices for Crude Oil and Petroleum Products
Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23 362 334 318 706Production% of41.1Diesel pricesAdministrationpropanedrivers3 Outlook for GulfSpot
Transformation from spots to waves in a model of actin pattern formation
Stephen Whitelam; Till Bretschneider; Nigel J. Burroughs
2009-05-18T23:59:59.000Z
Actin networks in certain single-celled organisms exhibit a complex pattern-forming dynamics that starts with the appearance of static spots of actin on the cell cortex. Spots soon become mobile, executing persistent random walks, and eventually give rise to traveling waves of actin. Here we describe a possible physical mechanism for this distinctive set of dynamic transformations, by equipping an excitable reaction-diffusion model with a field describing the spatial orientation of its chief constituent (which we consider to be actin). The interplay of anisotropic actin growth and spatial inhibition drives a transformation at fixed parameter values from static spots to moving spots to waves.
Status of Monte-Carlo Event Generators
Hoeche, Stefan; /SLAC
2011-08-11T23:59:59.000Z
Recent progress on general-purpose Monte-Carlo event generators is reviewed with emphasis on the simulation of hard QCD processes and subsequent parton cascades. Describing full final states of high-energy particle collisions in contemporary experiments is an intricate task. Hundreds of particles are typically produced, and the reactions involve both large and small momentum transfer. The high-dimensional phase space makes an exact solution of the problem impossible. Instead, one typically resorts to regarding events as factorized into different steps, ordered descending in the mass scales or invariant momentum transfers which are involved. In this picture, a hard interaction, described through fixed-order perturbation theory, is followed by multiple Bremsstrahlung emissions off initial- and final-state and, finally, by the hadronization process, which binds QCD partons into color-neutral hadrons. Each of these steps can be treated independently, which is the basic concept inherent to general-purpose event generators. Their development is nowadays often focused on an improved description of radiative corrections to hard processes through perturbative QCD. In this context, the concept of jets is introduced, which allows to relate sprays of hadronic particles in detectors to the partons in perturbation theory. In this talk, we briefly review recent progress on perturbative QCD in event generation. The main focus lies on the general-purpose Monte-Carlo programs HERWIG, PYTHIA and SHERPA, which will be the workhorses for LHC phenomenology. A detailed description of the physics models included in these generators can be found in [8]. We also discuss matrix-element generators, which provide the parton-level input for general-purpose Monte Carlo.
Basden, Alastair
2015-01-01T23:59:59.000Z
The performance of a wide-field adaptive optics system depends on input design parameters. Here we investigate the performance of a multi-conjugate adaptive optics system design for the European Extremely Large Telescope, using an end-to-end Monte-Carlo adaptive optics simulation tool, DASP. We consider parameters such as the number of laser guide stars, sodium layer depth, wavefront sensor pixel scale, number of deformable mirrors, mirror conjugation and actuator pitch. We provide potential areas where costs savings can be made, and investigate trade-offs between performance and cost. We conclude that a 6 laser guide star system using 3 DMs seems to be a sweet spot for performance and cost compromise.
A Monte Carlo algorithm for degenerate plasmas
Turrell, A.E., E-mail: a.turrell09@imperial.ac.uk; Sherlock, M.; Rose, S.J.
2013-09-15T23:59:59.000Z
A procedure for performing Monte Carlo calculations of plasmas with an arbitrary level of degeneracy is outlined. It has possible applications in inertial confinement fusion and astrophysics. Degenerate particles are initialised according to the Fermi–Dirac distribution function, and scattering is via a Pauli blocked binary collision approximation. The algorithm is tested against degenerate electron–ion equilibration, and the degenerate resistivity transport coefficient from unmagnetised first order transport theory. The code is applied to the cold fuel shell and alpha particle equilibration problem of inertial confinement fusion.
Energy Monte Carlo (EMCEE) | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaP a g eWorksVillagesource History(RedirectedEl Segundo,EnerNOC Incsource History ViewEnergyEnergy Monte
Monte Carlo errors with less errors
Ulli Wolff
2006-11-29T23:59:59.000Z
We explain in detail how to estimate mean values and assess statistical errors for arbitrary functions of elementary observables in Monte Carlo simulations. The method is to estimate and sum the relevant autocorrelation functions, which is argued to produce more certain error estimates than binning techniques and hence to help toward a better exploitation of expensive simulations. An effective integrated autocorrelation time is computed which is suitable to benchmark efficiencies of simulation algorithms with regard to specific observables of interest. A Matlab code is offered for download that implements the method. It can also combine independent runs (replica) allowing to judge their consistency.
Marcus, Ryan C. [Los Alamos National Laboratory
2012-07-24T23:59:59.000Z
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.
Metodos de Monte Carlo Paulo Roberto de Carvalho Junior
JÂ´unior MÂ´etodos de Monte Carlo #12;Exemplo: CÂ´alculo de Paulo Roberto de Carvalho JÂ´unior MÂ´etodos de Monte Carlo #12;Exemplo: CÂ´alculo de EquaÂ¸c~ao da Circunfer^encia: x2 + y2 = r2 x2 + y2 = 1 AQ Paulo Roberto de Carvalho JÂ´unior MÂ´etodos de Monte Carlo #12;Algoritmo: CÂ´alculo de double calc
Kinetic lattice Monte Carlo simulations of interdiffusion in...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Abstract: Point-defect-mediated diffusion processes are investigated in strained SiGe alloys using kinetic lattice Monte Carlo *KLMC* simulation technique. The KLMC...
Monte Carlo Simulations of the Corrosion of Aluminoborosilicate...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Monte Carlo Simulations of the Corrosion of Aluminoborosilicate Glasses. Abstract: Aluminum is one of the most common components included in nuclear waste glasses. Therefore,...
Quantum Monte Carlo methods for nuclear physics
J. Carlson; S. Gandolfi; F. Pederiva; Steven C. Pieper; R. Schiavilla; K. E. Schmidt; R. B. Wiringa
2015-04-29T23:59:59.000Z
Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-body interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.
Quantum Monte Carlo methods for nuclear physics
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Carlson, Joseph A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gandolfi, Stefano [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pederiva, Francesco [Univ. of Trento (Italy); Pieper, Steven C. [Argonne National Lab. (ANL), Argonne, IL (United States); Schiavilla, Rocco [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Schmidt, K. E, [Arizona State Univ., Tempe, AZ (United States); Wiringa, Robert B. [Argonne National Lab. (ANL), Argonne, IL (United States)
2012-01-01T23:59:59.000Z
Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-body interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.
Quantum Monte Carlo methods for nuclear physics
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Carlson, Joseph A.; Gandolfi, Stefano; Pederiva, Francesco; Pieper, Steven C.; Schiavilla, Rocco; Schmidt, K. E,; Wiringa, Robert B.
2014-10-19T23:59:59.000Z
Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-bodymore »interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.« less
Metallic lithium by quantum Monte Carlo
Sugiyama, G.; Zerah, G.; Alder, B.J.
1986-12-01T23:59:59.000Z
Lithium was chosen as the simplest known metal for the first application of quantum Monte Carlo methods in order to evaluate the accuracy of conventional one-electron band theories. Lithium has been extensively studied using such techniques. Band theory calculations have certain limitations in general and specifically in their application to lithium. Results depend on such factors as charge shape approximations (muffin tins), pseudopotentials (a special problem for lithium where the lack of rho core states requires a strong pseudopotential), and the form and parameters chosen for the exchange potential. The calculations are all one-electron methods in which the correlation effects are included in an ad hoc manner. This approximation may be particularly poor in the high compression regime, where the core states become delocalized. Furthermore, band theory provides only self-consistent results rather than strict limits on the energies. The quantum Monte Carlo method is a totally different technique using a many-body rather than a mean field approach which yields an upper bound on the energies. 18 refs., 4 figs., 1 tab.
Ichthyophthirius multifiliis (White Spot) Infections in Ruth Francis-Floyd and Peggy Reed2
Watson, Craig A.
CIR920 Ichthyophthirius multifiliis (White Spot) Infections in Fish1 Ruth Francis-Floyd and Peggy that causes "Ich" or "white spot disease." This disease is a major prob- lem to aquarists and commercial fish producers world wide. Ichthyophthirius is an important disease of tropical fish, goldfish, and food fish
Stochastic Dominance Tests for Risk Lovers: with Application to Oil Spot and Futures Markets
Chaudhuri, Sanjay
Stochastic Dominance Tests for Risk Lovers: with Application to Oil Spot and Futures Markets for risk averters and risk lovers to study the performance of the oil spot and futures markets in both pre that there is no arbitrage opportunity between these two markets and conclude that market efficiency and market rationality
Resistance Spot Welding of Galvanized Steel: Part I. Material Variations and Process Modifications
Eagar, Thomas W.
( l Resistance Spot Welding of Galvanized Steel: Part I. Material Variations and Process to determine their effects on the acceptable range of resistance spot welding conditions for galvanized steel upsloping and downsloping of the weld current, preheat current, postheat current, electrode tip geometry
Control of Black Spot of Roses with Sulphur-Copper Dust.
Lyle, E. W. (Eldon W.)
1944-01-01T23:59:59.000Z
-off. Black spot was controlled with dusting (less than 0.1% of leaflet infection on September 23) and 3nt to ;easoll e and - - the CONTROL OF BLACK SPOT OF ROSES WITH SULPHUR-COPPER DUST 23 Table 10. Effect of time of cutting off understock tope...
Integration of Contracted Renewable Energy and Spot Market Supply to Serve
Oren, Shmuel S.
Integration of Contracted Renewable Energy and Spot Market Supply to Serve Flexible Loads Anthony-mail: oren@ieor.berkeley.edu). Abstract: We present a contract for integrating renewable energy supply and electricity spot markets for serving deferrable electric loads in order to mitigate renewable energy
AUTOMATIC HOT SPOT DETECTION AND SEGMENTATION IN WHOLE BODY FDG-PET IMAGES Haiying Guan1
California at Santa Barbara, University of
. Liver, bone marrow and spleen sometimes also have mildly high FDG uptake which is higher than someAUTOMATIC HOT SPOT DETECTION AND SEGMENTATION IN WHOLE BODY FDG-PET IMAGES Haiying Guan1 , Toshiro a system for automatic hot spots detection and segmentation in whole body FDG-PET images. The main
Subauroral proton spots visualize the Pc1 source A. G. Yahnin,1
California at Berkeley, University of
Subauroral proton spots visualize the Pc1 source A. G. Yahnin,1 T. A. Yahnina,1 and H. U. Frey2 observations from the IMAGE spacecraft revealed a new type of proton aurora Â subauroral proton spots, which map onto the vicinity of the plasmapause. It has been suggested that this proton aurora is produced
The Effects of the Dysfunctional Spot Market for Electricity in California
The Effects of the Dysfunctional Spot Market for Electricity in California on the Cost of Forward), the Consortium for Electric Reliability Technology Solutions (CERTS) program on Reliability and Markets at the U Cruz, California. #12;ABSTRACT The unexpectedly high spot prices for electricity in the summer of 2000
The NordPool Market The spot and electricity forward relation
Pfeifer, Holger
of the lectures 1. The Nordic Power Market NordPool 2. The spot and electricity forward relation Establishing some modelling HJM approach to forwards Conclusions The system price is the equilibrium Reference price and electricity forward relation Spot price modelling HJM approach to forwards Conclusions Historical system price
Dynamic Interactions in the Western United States Electricity Spot Markets Christine A. Jerko
Dynamic Interactions in the Western United States Electricity Spot Markets Christine A. Jerko Economic Research Analyst at Tractebel Electricity & Gas International, Houston, TX James W. Mjelde interactions between six electricity spot markets in the western United States are examined using time series
Morphological changes in ultrafast laser ablation plumes with varying spot size
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Harilal, S. S.; Diwakar, P. K.; Polek, M. P.; Phillips, M. C.
2015-06-04T23:59:59.000Z
We investigated the role of spot size on plume morphology during ultrafast laser ablation of metal targets. Our results show that the spatial features of fs LA plumes are strongly dependent on the focal spot size. Two-dimensional self-emission images showed that the shape of the ultrafast laser ablation plumes changes from spherical to cylindrical with an increasing spot size from 100 to 600 ?m. The changes in plume morphology and internal structures are related to ion emission dynamics from the plasma, where broader angular ion distribution and faster ions are noticed for the smallest spot size used. The present resultsmore »clearly show that the morphological changes in the plume with spot size are independent of laser pulse width.« less
SU-E-J-72: Geant4 Simulations of Spot-Scanned Proton Beam Treatment Plans
Kanehira, T; Sutherland, K; Matsuura, T; Umegaki, K; Shirato, H [Hokkaido University, Sapporo, Hokkaido (Japan)
2014-06-01T23:59:59.000Z
Purpose: To evaluate density inhomogeneities which can effect dose distributions for real-time image gated spot-scanning proton therapy (RGPT), a dose calculation system, using treatment planning system VQA (Hitachi Ltd., Tokyo) spot position data, was developed based on Geant4. Methods: A Geant4 application was developed to simulate spot-scanned proton beams at Hokkaido University Hospital. A CT scan (0.98 × 0.98 × 1.25 mm) was performed for prostate cancer treatment with three or four inserted gold markers (diameter 1.5 mm, volume 1.77 mm3) in or near the target tumor. The CT data was read into VQA. A spot scanning plan was generated and exported to text files, specifying the beam energy and position of each spot. The text files were converted and read into our Geant4-based software. The spot position was converted into steering magnet field strength (in Tesla) for our beam nozzle. Individual protons were tracked from the vacuum chamber, through the helium chamber, steering magnets, dose monitors, etc., in a straight, horizontal line. The patient CT data was converted into materials with variable density and placed in a parametrized volume at the isocenter. Gold fiducial markers were represented in the CT data by two adjacent voxels (volume 2.38 mm3). 600,000 proton histories were tracked for each target spot. As one beam contained about 1,000 spots, approximately 600 million histories were recorded for each beam on a blade server. Two plans were considered: two beam horizontal opposed (90 and 270 degree) and three beam (0, 90 and 270 degree). Results: We are able to convert spot scanning plans from VQA and simulate them with our Geant4-based code. Our system can be used to evaluate the effect of dose reduction caused by gold markers used for RGPT. Conclusion: Our Geant4 application is able to calculate dose distributions for spot scanned proton therapy.
Monte Carlo Evaluation of Resampling-Based Hypothesis Tests
Boos, Dennis
of rejections. At each alternative this Monte Carlo estimate will be unbiased for the true power function of the function ( ), where (A) = 1 if A is true and = 0 otherwise. The connection to measurement error methods 1998 Abstract Monte Carlo estimation of the power of tests that require resampling can be very com
CERN-TH.6275/91 Monte Carlo Event Generation
Sjöstrand, Torbjörn
CERN-TH.6275/91 Monte Carlo Event Generation for LHC T. Sj¨ostrand CERN -- Geneva Abstract The necessity of event generators for LHC physics studies is illustrated, and the Monte Carlo approach is outlined. A survey is presented of existing event generators, followed by a more detailed study
RADIATIVE HEAT TRANSFER WITH QUASI-MONTE CARLO METHODS
RADIATIVE HEAT TRANSFER WITH QUASI-MONTE CARLO METHODS A. Kersch1 W. Moroko2 A. Schuster1 1Siemens of Quasi-Monte Carlo to this problem. 1.1 Radiative Heat Transfer Reactors In the manufacturing of the problems which can be solved by such a simulation is high accuracy modeling of the radiative heat transfer
Monte Carlo techniques applied to PERT networks
McGowan, Lawrence Lee
1964-01-01T23:59:59.000Z
distribution is given by: f(t;A, B, , I!) = ~ (t-A) (B t) A t -B {5) n. P. (B-A) = 0 A 5+1 + B (r+I) The mean is given by elsewhere u-. lj'k+1) B-A I The variance is given by 2 (Ix+IF+2) (a+I+3) uB+ BA and the mode is given by II: The parameters...; Statistics MONTE CARLO TECHNIQUES APPLIED TO PERT NETWORKS A Thesis By IAWRENCE LEE MCGOWAN Approved as to style arid content by: Chairman Committee Head of Department Member of Comm'ttee Member of Committee i August 1964 '] i P 'f TABLE...
Exploring theory space with Monte Carlo reweighting
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gainer, James S.; Lykken, Joseph; Matchev, Konstantin T.; Mrenna, Stephen; Park, Myeonghun
2014-10-13T23:59:59.000Z
Theories of new physics often involve a large number of unknown parameters which need to be scanned. Additionally, a putative signal in a particular channel may be due to a variety of distinct models of new physics. This makes experimental attempts to constrain the parameter space of motivated new physics models with a high degree of generality quite challenging. We describe how the reweighting of events may allow this challenge to be met, as fully simulated Monte Carlo samples generated for arbitrary benchmark models can be effectively re-used. In particular, we suggest procedures that allow more efficient collaboration between theoristsmore »and experimentalists in exploring large theory parameter spaces in a rigorous way at the LHC.« less
Correlations in the Monte Carlo Glauber model
Jean-Paul Blaizot; Wojciech Broniowski; Jean-Yves Ollitrault
2014-09-12T23:59:59.000Z
Event-by-event fluctuations of observables are often modeled using the Monte Carlo Glauber model, in which the energy is initially deposited in sources associated with wounded nucleons. In this paper, we analyze in detail the correlations between these sources in proton-nucleus and nucleus-nucleus collisions. There are correlations arising from nucleon-nucleon correlations within each nucleus, and correlations due to the collision mechanism, which we dub twin correlations. We investigate this new phenomenon in detail. At the RHIC and LHC energies, correlations are found to have modest effects on size and eccentricity fluctuations, such that the Glauber model produces to a good approximation a collection of independent sources.
Parametric Learning and Monte Carlo Optimization
Wolpert, David H
2007-01-01T23:59:59.000Z
This paper uncovers and explores the close relationship between Monte Carlo Optimization of a parametrized integral (MCO), Parametric machine-Learning (PL), and `blackbox' or `oracle'-based optimization (BO). We make four contributions. First, we prove that MCO is mathematically identical to a broad class of PL problems. This identity potentially provides a new application domain for all broadly applicable PL techniques: MCO. Second, we introduce immediate sampling, a new version of the Probability Collectives (PC) algorithm for blackbox optimization. Immediate sampling transforms the original BO problem into an MCO problem. Accordingly, by combining these first two contributions, we can apply all PL techniques to BO. In our third contribution we validate this way of improving BO by demonstrating that cross-validation and bagging improve immediate sampling. Finally, conventional MC and MCO procedures ignore the relationship between the sample point locations and the associated values of the integrand; only th...
Exploring theory space with Monte Carlo reweighting
Gainer, James S. [Univ. of Florida, Gainesville, FL (United States); Lykken, Joseph [Fermi National Accelerator Laboratory, Batavia, IL (United States); Matchev, Konstantin T. [Univ. of Florida, Gainesville, FL (United States); Mrenna, Stephen [Fermi National Accelerator Laboratory, Batavia, IL (United States); Park, Myeonghun [The Univ. of Tokyo, Kashiwa (Japan)
2014-10-01T23:59:59.000Z
Theories of new physics often involve a large number of unknown parameters which need to be scanned. Additionally, a putative signal in a particular channel may be due to a variety of distinct models of new physics. This makes experimental attempts to constrain the parameter space of motivated new physics models with a high degree of generality quite challenging. We describe how the reweighting of events may allow this challenge to be met, as fully simulated Monte Carlo samples generated for arbitrary benchmark models can be effectively re-used. In particular, we suggest procedures that allow more efficient collaboration between theorists and experimentalists in exploring large theory parameter spaces in a rigorous way at the LHC.
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
Monte Carlo Methods for Uncertainty Quantification Mike Giles Mathematical Institute, University of Oxford ERCOFTAC course on Mathematical Methods and Tools in Uncertainty Management and Quantification Lecture 1: Introduction and Monte Carlo basics some model applications random number generation Monte
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
Monte Carlo Methods for Uncertainty Quantification Mike Giles Mathematical Institute, University of Oxford ERCOFTAC course on Mathematical Methods and Tools in Uncertainty Management and Quantification: Introduction and Monte Carlo basics some model applications random number generation Monte Carlo estimation
Christian, Richard Travis
1986-01-01T23:59:59.000Z
Stricter Measures Called For The TPWD Increases Regulations on Red and Spotted Seatrout Illegal Netting 61 65 66 Drum TABLE OF CONTENTS (continued) IV CASE FINDINGS (continued) The Opposition Increases The Legislative Process Economic Impact... and spotted seatrout caught in Texas February 12 May 19 H. B. 980 S. B. 139 Called for a halt to harvest of red drum and spotted seatrout in Texas by all persons February 12 killed Red drum and spotted seat rout to be made permanently illegal...
Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots
Zhang, Jian-Shi; Giometti, C.S.; Tollaksen, S.L.
1987-09-04T23:59:59.000Z
After two-dimensional electrophoresis of proteins or the like, resulting in a polyacrylamide gel slab having a pattern of protein gel spots thereon, an individual protein gel spot is cored out from the slab, to form a gel spot core which is placed in an extraction tube, with a dialysis membrane across the lower end of the tube. Replicate gel spots can be cored out from replicate gel slabs and placed in the extraction tube. Molten agarose gel is poured into the extraction tube where the agarose gel hardens to form an immobilizing gel, covering the gel spot cores. The upper end portion of the extraction tube is filled with a volume of buffer solution, and the upper end is closed by another dialysis membrane. Upper and lower bodies of a buffer solution are brought into contact with the upper and lower membranes and are provided with electrodes connected to the positive and negative terminals of a dc power supply, thereby producing an electrical current which flows through the upper membrane, the volume of buffer solution, the agarose, the gel spot cores and the lower membrane. The current causes the proteins to be extracted electrophoretically from the gel spot cores, so that the extracted proteins accumulate and are contained in the space between the agarose gel and the upper membrane. 8 figs.
Iterative acceleration methods for Monte Carlo and deterministic criticality calculations
Urbatsch, T.J.
1995-11-01T23:59:59.000Z
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.
Sequential Monte Carlo Methods for Protein Folding
Peter Grassberger
2004-08-26T23:59:59.000Z
We describe a class of growth algorithms for finding low energy states of heteropolymers. These polymers form toy models for proteins, and the hope is that similar methods will ultimately be useful for finding native states of real proteins from heuristic or a priori determined force fields. These algorithms share with standard Markov chain Monte Carlo methods that they generate Gibbs-Boltzmann distributions, but they are not based on the strategy that this distribution is obtained as stationary state of a suitably constructed Markov chain. Rather, they are based on growing the polymer by successively adding individual particles, guiding the growth towards configurations with lower energies, and using "population control" to eliminate bad configurations and increase the number of "good ones". This is not done via a breadth-first implementation as in genetic algorithms, but depth-first via recursive backtracking. As seen from various benchmark tests, the resulting algorithms are extremely efficient for lattice models, and are still competitive with other methods for simple off-lattice models.
Retinal response of Macaca mulatta to picosecond laser pulses of varying energy and spot size
Roach, William P.
We investigate the relationship between the laser beam at the retina (spot size) and the extent of retinal injury from single ultrashort laser pulses. From previous studies it is believed that the retinal effect of single ...
The influence of purification protocol and pH on tomato spotted wilt virions
Shimek, Christina Marie
1993-01-01T23:59:59.000Z
Two purification protocols were tested for their influence on yield of tomato spotted wilt virions. Protocol "A" was developed by Black et al (2), modified by Mohammed et al (34), and described by Gonsalves and Trujillo (16). Protocol "B...
Calculation of the fast ion tail distribution for a spherically symmetric hot spot
McDevitt, C. J.; Tang, X.-Z.; Guo, Z. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Berk, H. L. [Department of Physics, University of Texas, Austin, Texas 78712 (United States)
2014-10-15T23:59:59.000Z
The fast ion tail for a spherically symmetric hot spot is computed via the solution of a simplified Fokker-Planck collision operator. Emphasis is placed on describing the energy scaling of the fast ion distribution function in the hot spot as well as the surrounding cold plasma throughout a broad range of collisionalities and temperatures. It is found that while the fast ion tail inside the hot spot is significantly depleted, leading to a reduction of the fusion yield in this region, a surplus of fast ions is observed in the neighboring cold plasma region. The presence of this surplus of fast ions in the neighboring cold region is shown to result in a partial recovery of the fusion yield lost in the hot spot.
X-ray imaging with monochromatic and small focal spot size sources
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of x-ray energy and intensity (under investigation) Measurements at the Elettra (Trieste) synchrotron Edge Response Function at ATF * Spot size * He Pipe added * 10 7 10 8...
Statistical geometry of particle packings. II. ``Weak spots'' in liquids Srikanth Sastry,1,
Stillinger, Frank
at the heart of hydrodynamic flow and diffusion properties in liquids, attributes that are absent or at least- stances constitute ``weak spots'' that preferentially serve as nucleation sites for boiling or cavitation
Photovoltaic ground fault and blind spot electrical simulations.
Flicker, Jack David; Johnson, Jay
2013-06-01T23:59:59.000Z
Ground faults in photovoltaic (PV) systems pose a fire and shock hazard. To mitigate these risks, AC-isolated, DC grounded PV systems in the United States use Ground Fault Protection Devices (GFPDs), e.g., fuses, to de-energize the PV system when there is a ground fault. Recently the effectiveness of these protection devices has come under question because multiple fires have started when ground faults went undetected. In order to understand the limitations of fuse-based ground fault protection in PV systems, analytical and numerical simulations of different ground faults were performed. The numerical simulations were conducted with Simulation Program with Integrated Circuit Emphasis (SPICE) using a circuit model of the PV system which included the modules, wiring, switchgear, grounded or ungrounded components, and the inverter. The derivation of the SPICE model and the results of parametric fault current studies are provided with varying array topologies, fuse sizes, and fault impedances. Closed-form analytical approximations for GFPD currents from faults to the grounded current carrying conductor-known as %E2%80%9Cblind spot%E2%80%9D ground faults-are derived to provide greater understanding of the influence of array impedances on fault currents. The behavior of the array during various ground faults is studied for a range of ground fault fuse sizes to determine if reducing the size of the fuse improves ground fault detection sensitivity. The results of the simulations show that reducing the amperage rating of the protective fuse does increase fault current detection sensitivity without increasing the likelihood of nuisance trips to a degree. Unfortunately, this benefit reaches a limit as fuses become smaller and their internal resistance increases to the point of becoming a major element in the fault current circuit.
The economic feasibility of computerized spot markets for feeder cattle in Texas
Glazener, Gretchen
1979-01-01T23:59:59.000Z
THE ECONOMIC FEASIBILITY OP COMPUTERIZED SPOT MARKETS FOR FEEDER CATTLE IN TEXAS A Thesis by GRETCHEN GLAZENER Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1979 Major Subject: Agricultural Economics THE ECONOMIC FEASIBILITY OF COMPUTERIZED SPOT MARKETS FOR FEEDER CATTLE IN TEXAS A Thesis by Gretchen Glazener Approved as to style and content by: irman of Co ittee) (Hea f Depar ment...
Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots
Zhang, Jian-Shi (Shanghai, CN); Giometti, Carol S. (Glenview, IL); Tollaksen, Sandra L. (Montgomery, IL)
1989-01-01T23:59:59.000Z
After two-dimensional electrophoresis of proteins or the like, resulting in a polyacrylamide gel slab having a pattern of protein gel spots thereon, an individual protein gel spot is cored out from the slab, to form a gel spot core which is placed in an extraction tube, with a dialysis membrane across the lower end of the tube. Replicate gel spots can be cored out from replicate gel slabs and placed in the extraction tube. Molten agarose gel is poured into the extraction tube where the agarose gel hardens to form an immobilizing gel, covering the gel spot cores. The upper end portion of the extraction tube is filled with a volume of buffer solution, and the upper end is closed by another dialysis membrane. Upper and lower bodies of a buffer solution are brought into contact with the upper and lower membranes and are provided with electrodes connected to the positive and negative terminals of a DC power supply, thereby producing an electrical current which flows through the upper membrane, the volume of buffer solution, the agarose, the gel spot cores and the lower membrane. The current causes the proteins to be extracted electrophoretically from the gel spot cores, so that the extracted proteins accumulate and are contained in the space between the agarose gel and the upper membrane. A high percentage extraction of proteins is achieved. The extracted proteins can be removed and subjected to partial digestion by trypsin or the like, followed by two-dimensional electrophoresis, resulting in a gel slab having a pattern of peptide gel spots which can be cored out and subjected to electrophoretic extraction to extract individual peptides.
Variance Reduction Techniques for Implicit Monte Carlo Simulations
Landman, Jacob Taylor
2013-09-19T23:59:59.000Z
The Implicit Monte Carlo (IMC) method is widely used for simulating thermal radiative transfer and solving the radiation transport equation. During an IMC run a grid network is constructed and particles are sourced into the problem to simulate...
An Analysis Tool for Flight Dynamics Monte Carlo Simulations
Restrepo, Carolina 1982-
2011-05-20T23:59:59.000Z
and analysis work to understand vehicle operating limits and identify circumstances that lead to mission failure. A Monte Carlo simulation approach that varies a wide range of physical parameters is typically used to generate thousands of test cases...
Spot size dependence of laser accelerated protons in thin multi-ion foils
Liu, Tung-Chang, E-mail: tcliu@umd.edu; Shao, Xi; Liu, Chuan-Sheng [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Eliasson, Bengt [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); SUPA, Department of Physics, Strathclyde University, Glasgow G4 0NG (United Kingdom); Wang, Jyhpyng [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Department of Physics, National Central University, Taoyuan 32001, Taiwan (China); Chen, Shih-Hung [Department of Physics, National Central University, Taoyuan 32001, Taiwan (China)
2014-06-15T23:59:59.000Z
We present a numerical study of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi-monoenergetic protons in laser proton acceleration using a thin carbon-hydrogen foil. The used proton acceleration scheme is a combination of laser radiation pressure and shielded Coulomb repulsion due to the carbon ions. We observe that the spot size plays a crucial role in determining the net charge of the electron-shielded carbon ion foil and consequently the efficiency of proton acceleration. Using a laser pulse with fixed input energy and pulse length impinging on a carbon-hydrogen foil, a laser beam with smaller spot sizes can generate higher energy but fewer quasi-monoenergetic protons. We studied the scaling of the proton energy with respect to the laser spot size and obtained an optimal spot size for maximum proton energy flux. Using the optimal spot size, we can generate an 80?MeV quasi-monoenergetic proton beam containing more than 10{sup 8} protons using a laser beam with power 250?TW and energy 10?J and a target of thickness 0.15 wavelength and 49 critical density made of 90% carbon and 10% hydrogen.
Shift: A Massively Parallel Monte Carlo Radiation Transport Package
Pandya, Tara M [ORNL; Johnson, Seth R [ORNL; Davidson, Gregory G [ORNL; Evans, Thomas M [ORNL; Hamilton, Steven P [ORNL
2015-01-01T23:59:59.000Z
This paper discusses the massively-parallel Monte Carlo radiation transport package, Shift, de- veloped at Oak Ridge National Laboratory. It reviews the capabilities, implementation, and parallel performance of this code package. Scaling results demonstrate very good strong and weak scaling behavior of the implemented algorithms. Benchmark results from various reactor problems show that Shift results compare well to other contemporary Monte Carlo codes and experimental results.
Implications of Monte Carlo Statistical Errors in Criticality Safety Assessments
Pevey, Ronald E.
2005-09-15T23:59:59.000Z
Most criticality safety calculations are performed using Monte Carlo techniques because of Monte Carlo's ability to handle complex three-dimensional geometries. For Monte Carlo calculations, the more histories sampled, the lower the standard deviation of the resulting estimates. The common intuition is, therefore, that the more histories, the better; as a result, analysts tend to run Monte Carlo analyses as long as possible (or at least to a minimum acceptable uncertainty). For Monte Carlo criticality safety analyses, however, the optimization situation is complicated by the fact that procedures usually require that an extra margin of safety be added because of the statistical uncertainty of the Monte Carlo calculations. This additional safety margin affects the impact of the choice of the calculational standard deviation, both on production and on safety. This paper shows that, under the assumptions of normally distributed benchmarking calculational errors and exact compliance with the upper subcritical limit (USL), the standard deviation that optimizes production is zero, but there is a non-zero value of the calculational standard deviation that minimizes the risk of inadvertently labeling a supercritical configuration as subcritical. Furthermore, this value is shown to be a simple function of the typical benchmarking step outcomes--the bias, the standard deviation of the bias, the upper subcritical limit, and the number of standard deviations added to calculated k-effectives before comparison to the USL.
Lattice Monte Carlo Simulations of Polymer Melts
Hsiao-Ping Hsu
2015-03-03T23:59:59.000Z
We use Monte Carlo simulations to study polymer melts consisting of fully flexible and moderately stiff chains in the bond fluctuation model at a volume fraction $0.5$. In order to reduce the local density fluctuations, we test a pre-packing process for the preparation of the initial configurations of the polymer melts, before the excluded volume interaction is switched on completely. This process leads to a significantly faster decrease of the number of overlapping monomers on the lattice. This is useful for simulating very large systems, where the statistical properties of the model with a marginally incomplete elimination of excluded volume violations are the same as those of the model with strictly excluded volume. We find that the internal mean square end-to-end distance for moderately stiff chains in a melt can be very well described by a freely rotating chain model with a precise estimate of the bond-bond orientational correlation between two successive bond vectors in equilibrium. The plot of the probability distributions of the reduced end-to-end distance of chains of different stiffness also shows that the data collapse is excellent and described very well by the Gaussian distribution for ideal chains. However, while our results confirm the systematic deviations between Gaussian statistics for the chain structure factor $S_c(q)$ [minimum in the Kratky-plot] found by Wittmer et al.~\\{EPL {\\bf 77} 56003 (2007).\\} for fully flexible chains in a melt, we show that for the available chain length these deviations are no longer visible, when the chain stiffness is included. The mean square bond length and the compressibility estimated from collective structure factors depend slightly on the stiffness of the chains.
Olson, R. E. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Leeper, R. J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2013-09-15T23:59:59.000Z
The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ?34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid” (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry.
An investigation of the dynamic separation of spot welds under plane tensile pulses
Ma, Bohan; Fan, Chunlei; Chen, Danian, E-mail: chdnch@nbu.edu.cn; Wang, Huanran; Zhou, Fenghua [Mechanics and Materials Science Research Center, Ningbo University, Zhejiang 315211 (China)
2014-08-07T23:59:59.000Z
We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results.
The Monte Carlo method in quantum field theory
Colin Morningstar
2007-02-20T23:59:59.000Z
This series of six lectures is an introduction to using the Monte Carlo method to carry out nonperturbative studies in quantum field theories. Path integrals in quantum field theory are reviewed, and their evaluation by the Monte Carlo method with Markov-chain based importance sampling is presented. Properties of Markov chains are discussed in detail and several proofs are presented, culminating in the fundamental limit theorem for irreducible Markov chains. The example of a real scalar field theory is used to illustrate the Metropolis-Hastings method and to demonstrate the effectiveness of an action-preserving (microcanonical) local updating algorithm in reducing autocorrelations. The goal of these lectures is to provide the beginner with the basic skills needed to start carrying out Monte Carlo studies in quantum field theories, as well as to present the underlying theoretical foundations of the method.
Quantum Monte Carlo Calculations of Light Nuclei Using Chiral Potentials
J. E. Lynn; J. Carlson; E. Epelbaum; S. Gandolfi; A. Gezerlis; A. Schwenk
2014-11-09T23:59:59.000Z
We present the first Green's function Monte Carlo calculations of light nuclei with nuclear interactions derived from chiral effective field theory up to next-to-next-to-leading order. Up to this order, the interactions can be constructed in a local form and are therefore amenable to quantum Monte Carlo calculations. We demonstrate a systematic improvement with each order for the binding energies of $A=3$ and $A=4$ systems. We also carry out the first few-body tests to study perturbative expansions of chiral potentials at different orders, finding that higher-order corrections are more perturbative for softer interactions. Our results confirm the necessity of a three-body force for correct reproduction of experimental binding energies and radii, and pave the way for studying few- and many-nucleon systems using quantum Monte Carlo methods with chiral interactions.
Real-time spot size camera for pulsed high-energy radiographic machines
Watson, S.A.
1993-01-01T23:59:59.000Z
The focal spot size of an x-ray source is a critical parameter which degrades resolution in a flash radiograph. For best results, a small round focal spot is required. Therefore, a fast and accurate measurement of the spot size is highly desirable to facilitate machine tuning. This paper describes two systems developed for Los Alamos National Laboratory's Pulsed High-Energy Radiographic Machine Emitting X-rays (PHERMEX) facility. The first uses a CCD camera combined with high-brightness floors, while the second utilizes phosphor storage screens. Other techniques typically record only the line spread function on radiographic film, while systems in this paper measure the more general two-dimensional point-spread function and associated modulation transfer function in real time for shot-to-shot comparison.
Real-time spot size camera for pulsed high-energy radiographic machines
Watson, S.A.
1993-06-01T23:59:59.000Z
The focal spot size of an x-ray source is a critical parameter which degrades resolution in a flash radiograph. For best results, a small round focal spot is required. Therefore, a fast and accurate measurement of the spot size is highly desirable to facilitate machine tuning. This paper describes two systems developed for Los Alamos National Laboratory`s Pulsed High-Energy Radiographic Machine Emitting X-rays (PHERMEX) facility. The first uses a CCD camera combined with high-brightness floors, while the second utilizes phosphor storage screens. Other techniques typically record only the line spread function on radiographic film, while systems in this paper measure the more general two-dimensional point-spread function and associated modulation transfer function in real time for shot-to-shot comparison.
Electron depletion via cathode spot dispersion of dielectric powder into an overhead plasma
Gillman, Eric D. [Naval Research Laboratory, 4555 Overlook Ave SW, Washington, District of Columbia 20375 (United States)] [Naval Research Laboratory, 4555 Overlook Ave SW, Washington, District of Columbia 20375 (United States); Foster, John E. [Department of Nuclear Engineering and Radiological Sciences (NERS), University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, Michigan 48109 (United States)] [Department of Nuclear Engineering and Radiological Sciences (NERS), University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, Michigan 48109 (United States)
2013-11-15T23:59:59.000Z
The effectiveness of cathode spot delivered dielectric particles for the purpose of plasma depletion is investigated. Here, cathode spot flows kinetically entrain and accelerate dielectric particles originally at rest into a background plasma. The time variation of the background plasma density is tracked using a cylindrical Langmuir probe biased approximately at electron saturation. As inferred from changes in the electron saturation current, depletion fractions of up to 95% are observed. This method could be exploited as a means of communications blackout mitigation for manned and unmanned reentering spacecraft as well as any high speed vehicle enveloped by a dense plasma layer.
Six years of monitoring annual changes in a freshwater marsh with SPOT HRV data
Mackey, H.E. Jr.
1992-01-01T23:59:59.000Z
Fifteen dates of spring-time SPOT HRV data along with near-concurrent vertical aerial photographic and phenological data from spring 1987 through spring 1992 were analyzed to monitor annual changes in a 150-hectare, southeastern floodplain marsh. The marsh underwent rapid changes during the six years from a swamp dominated by non-persistent, thermally tolerant macrophytes to persistent macrophyte and shrub-scrub communities as reactor discharges declined to Pen Branch. Savannah River flooding was also important in the timing of the shift of these wetland communities. SPOT HRV data proved to be an efficient and effective method to monitor trends in these wetland community changes.
Six years of monitoring annual changes in a freshwater marsh with SPOT HRV data
Mackey, H.E. Jr.
1992-12-01T23:59:59.000Z
Fifteen dates of spring-time SPOT HRV data along with near-concurrent vertical aerial photographic and phenological data from spring 1987 through spring 1992 were analyzed to monitor annual changes in a 150-hectare, southeastern floodplain marsh. The marsh underwent rapid changes during the six years from a swamp dominated by non-persistent, thermally tolerant macrophytes to persistent macrophyte and shrub-scrub communities as reactor discharges declined to Pen Branch. Savannah River flooding was also important in the timing of the shift of these wetland communities. SPOT HRV data proved to be an efficient and effective method to monitor trends in these wetland community changes.
Monte Carlo sampling from the quantum state space. II
Yi-Lin Seah; Jiangwei Shang; Hui Khoon Ng; David John Nott; Berthold-Georg Englert
2015-04-27T23:59:59.000Z
High-quality random samples of quantum states are needed for a variety of tasks in quantum information and quantum computation. Searching the high-dimensional quantum state space for a global maximum of an objective function with many local maxima or evaluating an integral over a region in the quantum state space are but two exemplary applications of many. These tasks can only be performed reliably and efficiently with Monte Carlo methods, which involve good samplings of the parameter space in accordance with the relevant target distribution. We show how the Markov-chain Monte Carlo method known as Hamiltonian Monte Carlo, or hybrid Monte Carlo, can be adapted to this context. It is applicable when an efficient parameterization of the state space is available. The resulting random walk is entirely inside the physical parameter space, and the Hamiltonian dynamics enable us to take big steps, thereby avoiding strong correlations between successive sample points while enjoying a high acceptance rate. We use examples of single and double qubit measurements for illustration.
Kinetic Monte Carlo approach to modeling dislocation mobility
Cai, Wei
surface diffusion and growth processes [3], in which the energy barriers for the atomic mechanisms the evolution of a physical system through numerical sampling of (Markovian) sto- chastic processes. While the traditional Monte Carlo (MC) method is applied to sample systems in or close to the thermal equilibrium, k
A Monte Carlo Approach for Football Play Generation Kennard Laviers
Sukthankar, Gita Reese
A Monte Carlo Approach for Football Play Generation Kennard Laviers School of EECS U. of Central, adversarial games and demonstrate its utility at gen- erating American football plays for Rush Football 2008. In football, like in many other multi-agent games, the actions of all of the agents are not equally crucial
Evolutionary Monte Carlo for protein folding simulations Faming Lianga)
Liang, Faming
Evolutionary Monte Carlo for protein folding simulations Faming Lianga) Department of Statistics to simulations of protein folding on simple lattice models, and to finding the ground state of a protein. In all structures in protein folding. The numerical results show that it is drastically superior to other methods
Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations
Lisal, Martin
Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations C.M. COLINAa,b, *, C and speed of sound for carbon dioxide (CO2) in the supercritical region, using the fluctuation method based: Fluctuations; Carbon dioxide; 2CLJQ; JouleThomson coefficient; Speed of sound INTRODUCTION Simulation methods
Path Integral Monte-Carlo Calculations for Relativistic Oscillator
Alexandr Ivanov; Oleg Pavlovsky
2014-11-11T23:59:59.000Z
The problem of Relativistic Oscillator has been studied in the framework of Path Integral Monte-Carlo(PIMC) approach. Ultra-relativistic and non-relativistic limits have been discussed. We show that PIMC method can be effectively used for investigation of relativistic systems.
Calculating coherent pair production with Monte Carlo methods
Bottcher, C.; Strayer, M.R.
1989-01-01T23:59:59.000Z
We discuss calculations of the coherent electromagnetic pair production in ultra-relativistic hadron collisions. This type of production, in lowest order, is obtained from three diagrams which contain two virtual photons. We discuss simple Monte Carlo methods for evaluating these classes of diagrams without recourse to involved algebraic reduction schemes. 19 refs., 11 figs.
Monte Carlo Simulations of Thermal Conductivity in Nanoporous Si Membranes
1 Monte Carlo Simulations of Thermal Conductivity in Nanoporous Si Membranes Stefanie Wolf1 transport in Si nanomeshes. Phonons are treated semiclassically as particles of specific energy and velocity, ii) the roughness amplitude of the pore surfaces on the thermal conductivity of the nanomeshes. We
Nonlocal Monte Carlo algorithms for statistical physics applications
Janke, Wolfhard
magnets to polymers or proteins, to mention only a few classical problems. Quantum statistical problems different theoretical approaches such as field theory or series expansions, and, of course, with experimentsNonlocal Monte Carlo algorithms for statistical physics applications Wolfhard Janke1 Institut fu
Auxiliary field Monte Carlo for charged particles A. C. Maggs
Maggs, Anthony
~ . This is the wrong statistical weight for particles interacting via Coulomb's law. While evaluation of the energy; accepted 20 November 2003 This article describes Monte Carlo algorithms for charged systems using.1063/1.1642587 I. INTRODUCTION Fast methods for calculating Coulomb interactions are of the greatest importance
MCMs: Early History and The Basics Monte Carlo Methods
Mascagni, Michael
: Early History and The Basics The Stars Align at Los Alamos The Technology The Technology Simulation viaMCMs: Early History and The Basics Monte Carlo Methods: Early History and The Basics Prof. Michael: http://www.cs.fsu.edu/mascagni #12;MCMs: Early History and The Basics Outline of the Talk Early History
Monte Carlo: in the beginning and some great expectations
Metropolis, N.
1985-01-01T23:59:59.000Z
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.
ENVIRONMENTAL MODELING: 1 APPLICATIONS: MONTE CARLO SENSITIVITY SIMULATIONS
Dimov, Ivan
SIMULATIONS TO THE PROBLEM OF AIR POLLUTION TRANSPORT 3 1.1 The Danish Eulerian Model #12;Chapter 1 APPLICATIONS: MONTE CARLO SENSITIVITY SIMULATIONS TO THE PROBLEM OF AIR POLLUTION of pollutants in a real-live scenario of air-pollution transport over Europe. First, the developed technique
Romano, Paul K. (Paul Kollath)
2013-01-01T23:59:59.000Z
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 ...
Types of random numbers and Monte Carlo Methods Pseudorandom number generation
Mascagni, Michael
Types of random numbers and Monte Carlo Methods Pseudorandom number generation Quasirandom number generation Conclusions WE246: Random Number Generation A Practitioner's Overview Prof. Michael Mascagni #12;Types of random numbers and Monte Carlo Methods Pseudorandom number generation Quasirandom number
Guan, Fada 1982-
2012-04-27T23:59:59.000Z
Monte Carlo method has been successfully applied in simulating the particles transport problems. Most of the Monte Carlo simulation tools are static and they can only be used to perform the static simulations for the problems with fixed physics...
Thermoelectric transport perpendicular to thin-film heterostructures calculated using the Monte The Monte Carlo technique is used to calculate electrical as well as thermoelectric transport properties ballistic thermionic transport and fully diffusive thermoelectric transport is also described. DOI: 10
Details of the Electro-Mechanical (E/M) Impedance Health Monitoring of Spot-Welded Structural Joints
Giurgiutiu, Victor
1 Details of the Electro-Mechanical (E/M) Impedance Health Monitoring of Spot-Welded Structural sensors for health monitoring spot-welded structural joints. Experiments were performed on aluminum-electric transducer; Crack propagation; Crack detection. 1. INTRODUCTION Health monitoring of structural joints
Spot size dependence of laser accelerated protons in thin multi-ion foils Tung-Chang Liu,1,a)
polarized laser beam irradiates an ultra-thin foil and accelerates nearly the whole foil by the radiationSpot size dependence of laser accelerated protons in thin multi-ion foils Tung-Chang Liu,1,a) Xi of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi
Paris-Sud XI, Université de
Forecasting the conditional volatility of oil spot and futures prices with structural breaks of oil spot and futures prices using three GARCH-type models, i.e., linear GARCH, GARCH with structural that oil price fluctuations influence economic activity and financial sector (e.g., Jones and Kaul, 1996
DROPLET-BASED HOT SPOT COOLING USING TOPLESS DIGITAL MICROFLUIDICS ON A PRINTED CIRCUIT BOARD
Paris-Sud XI, Université de
DROPLET-BASED HOT SPOT COOLING USING TOPLESS DIGITAL MICROFLUIDICS ON A PRINTED CIRCUIT BOARD Phil demonstrated a cooling method on a "digital microfluidics" platform whereby discrete droplets are manipulated and the effective flow rate of the droplets. The results presented here suggest that digital microfluidics
Chemical markers of possible hot spots on Mars Ah-San Wong and Sushil K. Atreya
Atreya, Sushil
Chemical markers of possible hot spots on Mars Ah-San Wong and Sushil K. Atreya Department not be ruled out. If outgassing does occur somewhere on Mars, water, carbon dioxide, sulfur species, methane, and to a lesser extent, halogens would be the likely molecules of outgassing, based on terrestrial analogs
www.fruit.cornell.edu How do I manage Spotted Wing Drosophila (SWD)
Chen, Tsuhan
Fruit Resources www.fruit.cornell.edu 1 How do I manage Spotted Wing Drosophila (SWD) in my garden from Asia, showed up in California in 2008 and has since been reported in most states as well as parts vinegar flies. Adult flies are 2-3 mm in length, with red eyes and a tan- colored body with darker bands
Imaging seismic velocity structure beneath the Iceland hot spot: A finite frequency approach
Shen, Yang
Imaging seismic velocity structure beneath the Iceland hot spot: A finite frequency approach Shu and S wave speeds extending from shallow mantle to 400 km depth beneath Iceland. In reality, seismic waves anomaly beneath Iceland and its geodynamic implications. We developed a tomographic method that utilizes
Modified Fresnel zone plates with sharp Gaussian focal spots Qing Cao and Jurgen Jahns
Jahns, Jürgen
Modified Fresnel zone plates with sharp Gaussian focal spots Qing Cao and J¨urgen Jahns Traditional Fresnel zone plates (TFZPs) and photon sieves [1, 2, 3] can be used for the focusing and imaging of soft x.e. a modified Fresnel zone plate, MFZP) can realized the same functions as a photon sieve. In particular, we
Revised 1/11/05 SPOTTED SEAL (Phoca largha): Alaska Stock
during the breeding season, and only spotted seals are strongly associated with pack ice (Shaughnessy conducted over the Bering Sea pack ice in spring and along the western Alaska coast during summer (Rugh et overwinter in the Bering Sea along the ice edge and make east-west movements along the edge (Lowry et al
Preliminary Report Biology of the Spotted Seal (Phoca largha) in Alaska from 1962 to 2008
is present, spotted seals are found along the pack ice edge where the ice is loosely packed (Fay 1974 in that they prefer loose pack ice and they will readily haul out on land, which they do frequently in summer (e that are dependent on sea ice during some portion of the year; the other three species include the bearded seal
Title of Dissertation / Thesis: PERFORMANCE AND ANALYSIS OF SPOT TRUCK-LOAD
Bertini, Robert L.
ABSTRACT Title of Dissertation / Thesis: PERFORMANCE AND ANALYSIS OF SPOT TRUCK-LOAD PROCUREMENT MARKETS USING SEQUENTIAL AUCTIONS Miguel Andres Figliozzi, Ph.D., 2004 Dissertation / Thesis Directed By By Miguel Andres Figliozzi Dissertation submitted to the Faculty of the Graduate School of the University
Dynamical Spot Queries to Improve Specificity in P450s based Multi-Drugs Monitoring
De Micheli, Giovanni
Dynamical Spot Queries to Improve Specificity in P450s based Multi-Drugs Monitoring Sandro Carrara accurate and frequent monitoring of drugs metabolic response in living organisms during drug treatments monitoring of the patient's drug metabolism is essential as the metabolic pathways efficacy is highly
Predicting the Failure of Ultrasonic Spot Welds by Pull-out from Sheet Metal
Thouless, Michael
-mode fracture of the base metal, the cohesive parameters for ductile fracture of an aluminum alloy were parameters (characteristic strength and toughness) associated with the shear and normal modes of ductile, cohesive zone, fracture, cohesive strength, toughness. (March 2006) #12;2 1. Introduction Ultrasonic spot
Spot weldability of TRIP assisted steels with high carbon and aluminium contents
Cambridge, University of
Spot weldability of TRIP assisted steels with high carbon and aluminium contents G. S. Jung1 , K. Y of their aluminium concentrations of 3?5 or 5?6 wt-% and which also have high carbon contents of 0?3 or 0?4 wt-% when-ferrite, Ductility ratio, Weldability Introduction One variant of low alloy steel that benefits from transformation
Subauroral morning proton spots (SAMPS) as a result of plasmapause-ring-current interaction
Østgaard, Nikolai
Subauroral morning proton spots (SAMPS) as a result of plasmapause-ring-current interaction H. U) that rotate with 7095% of the Earth's corotation speed. Coincident particle measurements by DMSP confirm of the previous geomagnetic storm with the lowest latitude observations after the strongest storms. The rotation
On the Interaction of Jupiter's Great Red Spot and Zonal Jet Streams SUSHIL SHETTY
Marcus, Philip S.
On the Interaction of Jupiter's Great Red Spot and Zonal Jet Streams SUSHIL SHETTY Department- boring jet streams, the shear imposed on the GRS by the jet streams, and the vertical entropy gradient (i. The westward-going jet stream to the north of the GRS and the eastward-going jet stream to its south are each
Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules
Garnier, Josselin
Self-consistent analysis of the hot spot dynamics for inertial confinement fusion capsules J. Sanz Hydrodynamic stability of inertial confinement fusion ICF capsules during the deceleration stage has been re October 2005; published online 11 November 2005 In the context of the French Laser-Mégajoule fusion
A Scalable Soft Spot Analysis Methodology for Compound Noise Effects in Nano-meter Circuits
California at San Diego, University of
A Scalable Soft Spot Analysis Methodology for Compound Noise Effects in Nano-meter Circuits Chong methodology to study the vulnerability of digital ICs exposed to nano-meter noise and transient soft errors. First, we define "softness" as an important characteristic to gauge system vulnerability. Then several
Joint Modelling of Gas and Electricity spot prices N. Frikha1 , V. Lemaire2
Boyer, Edmond
Joint Modelling of Gas and Electricity spot prices N. Frikha1 , V. Lemaire2 October 13, 2010 for developing a risk management framework as well as pricing of options. Many derivatives on both electricity to price projects in energy (see [12] for an introduction). Thus, modelling jointly the evolution of gas
Joint Modelling of Gas and Electricity spot prices N. Frikha1 , V. Lemaire2
Joint Modelling of Gas and Electricity spot prices N. Frikha1 , V. Lemaire2 October 9, 2009 for developing a risk management framework as well as pricing of options. Many derivatives on both electricity to price projects in energy (see [10] for an introduction). Thus, modelling jointly the evolution of gas
Optimal Spot Market Inventory Strategies in the Presence of Cost and Price Risk
Guo, Xin
low and selling high... An energy storage plant puts a utility in a position to buy electricity whenOptimal Spot Market Inventory Strategies in the Presence of Cost and Price Risk X. Guo, P. Kaminsky the risk of higher than anticipated demand for goods (see, e.g., [31] and the ref- erences therein
A NON-GAUSSIAN ORNSTEIN-UHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND
Kallsen, Jan
concepts from the Heath-Jarrow-Morton theory for interest rates to electricity markets to modelA NON-GAUSSIAN ORNSTEIN-UHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND DERIVATIVES for analytical pricing of electricity forward and futures contracts. Electricity forward and futures contracts
Temperature-Aware MPSoC Scheduling for Reducing Hot Spots and Gradients
Coskun, Ayse
to manufacture reliable systems while meeting energy and performance constraints. In this work, we solve the task, San Diego Abstract-- Thermal hot spots and temperature gradients on the die need to be minimized is optimal. We compare our technique against optimal scheduling methods for energy minimization, energy
Futures pricing in electricity markets based on stable CARMA spot models
Gerkmann, Ralf
Futures pricing in electricity markets based on stable CARMA spot models Gernot M¨uller Vortrag im years, electricity markets throughout the world have undergone massive changes due to deregulations risk but also against price movements. Consequently, statistical modeling and estimation of electricity
Reduced form electricity spot price modeling with a view towards spike risk
Gerkmann, Ralf
Reduced form electricity spot price modeling with a view towards spike risk Prof. Dr. Meyer. Februar 2010, 16:15 Uhr Seminarraum, Ludwigstraße 33 I The recent deregulation of electricity markets has led to the creation of energy exchanges, where the electricity is freely traded. We study the most
Word Spotting for Handwritten Documents using Chamfer Distance and Dynamic Time Warping
El-Sana, Jihad
in libraries around the world. The desire to ac- cess, search, and explore these documents paves the way, taken from Juma'a Al Majid Center - Dubai, and obtained encouraging results. Keywords: Word Spotting to rare documents and old manuscripts, which are kept in brick-and-mortar libraries around the world
Spoken Keyword Spotting via Multi-Lattice Alignment Hui Lin, Alex Stupakov and Jeff Bilmes
Noble, William Stafford
, or impossible for the user to enter a search query using a standard keyboard. For example, speech queries and a second phone lattice repre- senting a long utterance needing to be searched. We implement this joint representation. Index Terms: speech lattice, keyword spotting, graphical mod- els, lattice alignment 1
Barrios, M. A.; Suter, L. J.; Glenn, S.; Benedetti, L. R.; Bradley, D. K.; Collins, G. W.; Hammel, B. A.; Izumi, N.; Ma, T.; Scott, H.; Smalyuk, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Regan, S. P.; Epstein, R. [Laboratory for Laser Energetics, University of Rochester 250 East River Road, Rochester, New York 14623-199 (United States)] [Laboratory for Laser Energetics, University of Rochester 250 East River Road, Rochester, New York 14623-199 (United States); Kyrala, G. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2013-07-15T23:59:59.000Z
Bright spots in the hot spot intensity profile of gated x-ray images of ignition-scale implosions at the National Ignition Facility [G. H. Miller et al., Opt. Eng. 443, (2004)] are observed. X-ray images of cryogenically layered deuterium-tritium (DT) and tritium-hydrogen-deuterium (THD) ice capsules, and gas filled plastic shell capsules (Symcap) were recorded along the hohlraum symmetry axis. Heterogeneous mixing of ablator material and fuel into the hot spot (i.e., hot-spot mix) by hydrodynamic instabilities causes the bright spots. Hot-spot mix increases the radiative cooling of the hot spot. Fourier analysis of the x-ray images is used to quantify the evolution of bright spots in both x- and k-space. Bright spot images were azimuthally binned to characterize bright spot location relative to known isolated defects on the capsule surface. A strong correlation is observed between bright spot location and the fill tube for both Symcap and cryogenically layered DT and THD ice targets, indicating the fill tube is a significant seed for the ablation front instability causing hot-spot mix. The fill tube is the predominant seed for Symcaps, while other capsule non-uniformities are dominant seeds for the cryogenically layered DT and THD ice targets. A comparison of the bright spot power observed for Si- and Ge-doped ablator targets shows heterogeneous mix in Symcap targets is mostly material from the doped ablator layer.
Srinivasan, Bhuvana, E-mail: srinbhu@vt.edu [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Aerospace and Ocean Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Tang, Xian-Zhu, E-mail: xtang@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-10-15T23:59:59.000Z
In an inertial confinement fusion target, energy loss due to thermal conduction from the hot-spot will inevitably ablate fuel ice into the hot-spot, resulting in a more massive but cooler hot-spot, which negatively impacts fusion yield. Hydrodynamic mix due to Rayleigh-Taylor instability at the gas-ice interface can aggravate the problem via an increased gas-ice interfacial area across which energy transfer from the hot-spot and ice can be enhanced. Here, this mix-enhanced transport effect on hot-spot fusion-performance degradation is quantified using contrasting 1D and 2D hydrodynamic simulations, and its dependence on effective acceleration, Atwood number, and ablation speed is identified.
Hot-spot mix in ignition-scale implosions on the NIF
Regan, S. P.; Epstein, R.; McCrory, R. L.; Meyerhofer, D. D.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); Hammel, B. A.; Suter, L. J.; Ralph, J.; Scott, H.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Cerjan, C.; Collins, G. W.; Dixit, S. N.; Doeppner, T.; Edwards, M. J.; Farley, D. R.; Glenn, S.; Glenzer, S. H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others
2012-05-15T23:59:59.000Z
Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National Ignition Facility (NIF) ignition targets consist of a plastic ablator surrounding a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. The Rev. 5 ablator is doped with Ge to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraum x-ray drive [D. S. Clark et al., Phys. Plasmas 17, 052703 (2010)]. Richtmyer-Meshkov and Rayleigh-Taylor hydrodynamic instabilities seeded by high-mode () ablator-surface perturbations can cause Ge-doped ablator to mix into the interior of the shell at the end of the acceleration phase [B. A. Hammel et al., Phys. Plasmas 18, 056310 (2011)]. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The Ge emission from tritium-hydrogen-deuterium (THD) and deuterium-tritium (DT) cryogenic targets and gas-filled plastic-shell capsules, which replace the THD layer with a mass-equivalent CH layer, was examined. The inferred amount of hot-spot-mix mass, estimated from the Ge K-shell line brightness using a detailed atomic physics code [J. J. MacFarlane et al., High Energy Density Phys. 3, 181 (2006)], is typically below the 75-ng allowance for hot-spot mix [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)]. Predictions of a simple mix model, based on linear growth of the measured surface-mass modulations, are consistent with the experimental results.
Hybrid Probabilistic Roadmap and Monte Carlo Methods for Biomolecule Conformational Changes
Han, Li
1 Hybrid Probabilistic Roadmap and Monte Carlo Methods for Biomolecule Conformational Changes Li Han 1 Keywords: Conformation space, conformational changes, Monte Carlo, probabilistic roadmaps. 1. In this work, we have developed a hybrid Probabilistic Roadmap and Monte Carlo planner for biomolecule
Dynamic properties along the neutral line of a delta spot inferred from high-resolution observations
Cristaldi, A.; Guglielmino, S. L.; Zuccarello, F.; Falco, M. [Dipartimento di Fisica e Astronomia-Sezione Astrofisica, Università di Catania, via S. Sofia 78, I-95123 Catania (Italy); Romano, P. [INAF-Osservatorio Astrofisico di Catania, via S. Sofia 78, I-95123 Catania (Italy); Rouppe van der Voort, L. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway); De la Cruz Rodríguez, J. [Institute for Solar Physics, Department of Astronomy, Stockholm University, Albanova University Center, SE-10691 Stockholm (Sweden); Ermolli, I. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monte Porzio Catone (Italy); Criscuoli, S. [NSO-National Solar Observatory, Sacramento Peak Box 62, Sunspot, NM 88349 (United States)
2014-07-10T23:59:59.000Z
Delta (?) spots are complex magnetic configurations of sunspots characterized by umbrae of opposite polarity sharing a common penumbra. In order to investigate the fine structure of the region separating the two magnetic polarities of a ? spot, we studied the morphology, the magnetic configuration, and the velocity field in such a region using observations of active region (AR) NOAA 11267 obtained with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish Solar Telescope on 2011 August 6. The analysis of CRISP data shows upflows and downflows of ? ± 3 km s{sup –1} in proximity of the ? spot polarity inversion line (PIL), and horizontal motions along the PIL of the order of ?1 km s{sup –1}. The results obtained from the SIR inversion of CRISP data also indicate that the transverse magnetic field in the brighter region separating the two opposite magnetic polarities of the ? spot is tilted about ?45° with respect to the PIL. Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations confirm the presence of motions of ? ± 3 km s{sup –1} in proximity of the PIL, which were observed to last 15 hr. From the data analyzed, we conclude that the steady, persistent, and subsonic motions observed along the ? spot PIL can be interpreted as being due to Evershed flows occurring in the penumbral filaments that show a curved, wrapped configuration. The fluting of the penumbral filaments and their bending, continuously increased by the approaching motion of the negative umbra toward the positive one, give rise to the complex line-of-sight velocity maps that we observed.
Dowdell, Stephen; Paganetti, Harald [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States)] [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Grassberger, Clemens [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 and Centre for Proton Therapy, Paul Scherrer Institut, 5232 Villigen-PSI (Switzerland)] [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 and Centre for Proton Therapy, Paul Scherrer Institut, 5232 Villigen-PSI (Switzerland)
2013-12-15T23:59:59.000Z
Purpose: To compare motion effects in intensity modulated proton therapy (IMPT) lung treatments with different levels of intensity modulation.Methods: Spot scanning IMPT treatment plans were generated for ten lung cancer patients for 2.5Gy(RBE) and 12Gy(RBE) fractions and two distinct energy-dependent spot sizes (??8–17 mm and ?2–4 mm). IMPT plans were generated with the target homogeneity of each individual field restricted to <20% (IMPT{sub 20%}). These plans were compared to full IMPT (IMPT{sub full}), which had no restriction on the single field homogeneity. 4D Monte Carlo simulations were performed upon the patient 4DCT geometry, including deformable image registration and incorporating the detailed timing structure of the proton delivery system. Motion effects were quantified via comparison of the results of the 4D simulations (4D-IMPT{sub 20%}, 4D-IMPT{sub full}) with those of a 3D Monte Carlo simulation (3D-IMPT{sub 20%}, 3D-IMPT{sub full}) upon the planning CT using the equivalent uniform dose (EUD), V{sub 95} and D{sub 1}-D{sub 99}. The effects in normal lung were quantified using mean lung dose (MLD) and V{sub 90%}.Results: For 2.5Gy(RBE), the mean EUD for the large spot size is 99.9%± 2.8% for 4D-IMPT{sub 20%} compared to 100.1%± 2.9% for 4D-IMPT{sub full}. The corresponding values are 88.6%± 8.7% (4D-IMPT{sub 20%}) and 91.0%± 9.3% (4D-IMPT{sub full}) for the smaller spot size. The EUD value is higher in 69.7% of the considered deliveries for 4D-IMPT{sub full}. The V{sub 95} is also higher in 74.7% of the plans for 4D-IMPT{sub full}, implying that IMPT{sub full} plans experience less underdose compared to IMPT{sub 20%}. However, the target dose homogeneity is improved in the majority (67.8%) of plans for 4D-IMPT{sub 20%}. The higher EUD and V{sub 95} suggests that the degraded homogeneity in IMPT{sub full} is actually due to the introduction of hot spots in the target volume, perhaps resulting from the sharper in-target dose gradients. The greatest variations between the IMPT{sub 20%} and IMPT{sub full} deliveries are observed for patients with the largest motion amplitudes. These patients would likely be treated using gating or another motion mitigation technique, which was not the focus of this study.Conclusions: For the treatment parameters considered in this study, the differences between IMPT{sub full} and IMPT{sub 20%} are only likely to be clinically significant for patients with large (>20 mm) motion amplitudes.
Batuman, O.; Kuo, Y.-W.; Palmieri, M.; Rojas, M. R.; Gilbertson, R. L.
2010-01-01T23:59:59.000Z
Tomato chocolate spot virus, a member of a new torradovirusRepublic of Guatemala this virus being the causal agent oflate-spot-associated virus, revealed a genome composed of
Thermoelectric Coolers G. Jeffrey Snyder, Marco Soto, Randy Alley, David Koester, Bob Conner Nextreme Thermal spot temperatures when efficiently integrated with a heat spreader. Embedded thermoelectric cooling (e by today's advanced processors. Keywords Localized hot spot cooling. Thermoelectric, Peltier Cooling
Cambridge, University of
Finite element simulation of laser spot welding A. De, S. K. Maiti, C. A. Walsh and H. K. D. H laser spot welding, taking into account the temperature dependence of the physical properties and latent formation during laser spot welding, although the `double ellipsoidal' representation requires an a priori
Molecular physics and chemistry applications of quantum Monte Carlo
Reynolds, P.J.; Barnett, R.N.; Hammond, B.L.; Lester, W.A. Jr.
1985-09-01T23:59:59.000Z
We discuss recent work with the diffusion quantum Monte Carlo (QMC) method in its application to molecular systems. The formal correspondence of the imaginary time Schroedinger equation to a diffusion equation allows one to calculate quantum mechanical expectation values as Monte Carlo averages over an ensemble of random walks. We report work on atomic and molecular total energies, as well as properties including electron affinities, binding energies, reaction barriers, and moments of the electronic charge distribution. A brief discussion is given on how standard QMC must be modified for calculating properties. Calculated energies and properties are presented for a number of molecular systems, including He, F, F , H2, N, and N2. Recent progress in extending the basic QMC approach to the calculation of ''analytic'' (as opposed to finite-difference) derivatives of the energy is presented, together with an H2 potential-energy curve obtained using analytic derivatives. 39 refs., 1 fig., 2 tabs.
The hybrid Monte Carlo Algorithm and the chiral transition
Gupta, R.
1987-01-01T23:59:59.000Z
In this talk the author describes tests of the Hybrid Monte Carlo Algorithm for QCD done in collaboration with Greg Kilcup and Stephen Sharpe. We find that the acceptance in the glubal Metropolis step for Staggered fermions can be tuned and kept large without having to make the step-size prohibitively small. We present results for the finite temperature transition on 4/sup 4/ and 4 x 6/sup 3/ lattices using this algorithm.
Testing trivializing maps in the Hybrid Monte Carlo algorithm
Georg P. Engel; Stefan Schaefer
2011-02-09T23:59:59.000Z
We test a recent proposal to use approximate trivializing maps in a field theory to speed up Hybrid Monte Carlo simulations. Simulating the CP^{N-1} model, we find a small improvement with the leading order transformation, which is however compensated by the additional computational overhead. The scaling of the algorithm towards the continuum is not changed. In particular, the effect of the topological modes on the autocorrelation times is studied.
Mont Vernon, New Hampshire: Energy Resources | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaPLawrence County,1980) | Open EnergyMonetta, South Carolina: EnergyMonroeMonroeMonroe,Monsey,Mont
Artificial neural networks for centroiding elongated spots in Shack-Hartmann wavefront sensors
Mello, A T; Guzman, D; Guesalaga, A
2014-01-01T23:59:59.000Z
The use of Adaptive Optics in Extremely Large Telescopes brings new challenges, one of which is the treatment of Shack-Hartmann Wavefront sensors images. When using this type of sensors in conjunction with laser guide stars for sampling the pupil of telescopes with 30+ m in diameter, it is necessary to compute the centroid of elongated spots, whose elongation angle and aspect ratio are changing across the telescope pupil. Existing techniques such as Matched Filter have been considered as the best technique to compute the centroid of elongated spots, however they are not good at coping with the effect of a variation in the Sodium profile. In this work we propose a new technique using artificial neural networks, which take advantage of the neural network's ability to cope with changing conditions, outperforming existing techniques in this context. We have developed comprehensive simulations to explore this technique and compare it with existing algorithms.
Projectile containing metastable intermolecular composites and spot fire method of use
Asay, Blaine W.; Son, Steven F.; Sanders, V. Eric; Foley, Timothy; Novak, Alan M.; Busse, James R.
2012-07-31T23:59:59.000Z
A method for altering the course of a conflagration involving firing a projectile comprising a powder mixture of oxidant powder and nanosized reductant powder at velocity sufficient for a violent reaction between the oxidant powder and the nanosized reductant powder upon impact of the projectile, and causing impact of the projectile at a location chosen to draw a main fire to a spot fire at such location and thereby change the course of the conflagration, whereby the air near the chosen location is heated to a temperature sufficient to cause a spot fire at such location. The invention also includes a projectile useful for such method and said mixture preferably comprises a metastable intermolecular composite.
Vertically-tapered optical waveguide and optical spot transformer formed therefrom
Bakke, Thor; Sullivan, Charles T.
2004-07-27T23:59:59.000Z
An optical waveguide is disclosed in which a section of the waveguide core is vertically tapered during formation by spin coating by controlling the width of an underlying mesa structure. The optical waveguide can be formed from spin-coatable materials such as polymers, sol-gels and spin-on glasses. The vertically-tapered waveguide section can be used to provide a vertical expansion of an optical mode of light within the optical waveguide. A laterally-tapered section can be added adjacent to the vertically-tapered section to provide for a lateral expansion of the optical mode, thereby forming an optical spot-size transformer for efficient coupling of light between the optical waveguide and a single-mode optical fiber. Such a spot-size transformer can also be added to a III-V semiconductor device by post processing.
Lamellar structures and self-replicating spots in a reaction-diffusion system
Lee, K.J.; Swinney, H.L. (Center for Nonlinear Dynamics and the Department of Physics, The Univeristy of Texas, Austin, Texas 78712 (United States))
1995-03-01T23:59:59.000Z
Experiments on a ferrocyanide-iodate-sulfite reaction-diffusion system reveal several different planar spatial patterns: stationary lamellae arising from a transverse front instability and a front interaction; spot patterns that undergo a continuous process of growth through replication and death through overcrowding; waves with a repulsive front interaction; and conventional excitable waves that annihilate upon collision. The patterns form in a thin gel layer that is in contact with a continuously fed stirred reservoir. Lamellae are observed in both multistable and monostable regimes of the gel layer, while the self-replicating spots are found in a monostable regime. Numerical simulations on a one-dimensional, four-species model of the ferrocyanide-iodate-sulfite reaction describe the observed front interaction phenomena and some aspects of the bifurcation sequences observed in the laboratory experiments.
Fourier-phase analysis of the orbiting bright-spot model for AGN variability
V. Karas
1997-01-13T23:59:59.000Z
Fourier power spectra and phases of a signal from a large number of radiating sources orbiting around a black hole are investigated. It is assumed that the individual sources (bright spots) are located in an accretion disc and their lifetime exceeds the corresponding orbital period. This model is relevant for the short-time X-ray variability of active galactic nuclei. Previous works on this subject were mostly concentrated on temporal characteristics and power spectra of observed light curves. In our present contribution, Fourier phases are brought into consideration and studied systematically for a broad range of input parameters. In particular, conditions for the phase coherence are discussed. It is shown that one can discriminate between the two classes of models which are currently under consideration--orbital motion of a large number of sources versus short-lived independent flares--although parameters of the model are not completely arbitrary. It is also shown that predicted power spectra depend rather strongly on the spot distribution across the disk surface. We conclude that the orbital motion of the spots cannot be the only reason for the source fluctuations, but it certainly influences observational properties of the source intrinsic variability.
S. J. Tingay; E. Lenc; G. Brunetti; M. Bondi
2008-10-02T23:59:59.000Z
Images made with the VLBA have resolved the region in a nearby radio galaxy, Pictor A, where the relativistic jet that originates at the nucleus terminates in an interaction with the intergalactic medium, a so-called radio galaxy hot spot. This image provides the highest spatial resolution view of such an object to date (16 pc), more than three times better than previous VLBI observations of similar objects. The north-west Pictor A hot spot is resolved into a complex set of compact components, seen to coincide with the bright part of the hot spot imaged at arcsecond-scale resolution with the VLA. In addition to a comparison with VLA data, we compare our VLBA results with data from the HST and Chandra telescopes, as well as new Spitzer data. The presence of pc-scale components in the hot spot, identifying regions containing strong shocks in the fluid flow, leads us to explore the suggestion that they represent sites of synchrotron X-ray production, contributing to the integrated X-ray flux of the hot spot, along with X-rays from synchrotron self-Compton scattering. This scenario provides a natural explanation for the radio morphology of the hot spot and its integrated X-ray emission, leading to very different predictions for the higher energy X-ray spectrum compared to previous studies. From the sizes of the individual pc-scale components and their angular spread, we estimate that the jet width at the hot spot is in the range 70 - 700 pc, which is comparable to similar estimates in PKS 2153-69, 3C 205, and 4C 41.17. The lower limit in this range arises from the suggestion that the jet may dither in its direction as it passes through hot spot backflow material close to the jet termination point, creating a "dentist drill" effect on the inside of a cavity 700 pc in diameter.
FZ2MC: A Tool for Monte Carlo Transport Code Geometry Manipulation
Hackel, B M; Nielsen Jr., D E; Procassini, R J
2009-02-25T23:59:59.000Z
The process of creating and validating combinatorial geometry representations of complex systems for use in Monte Carlo transport simulations can be both time consuming and error prone. To simplify this process, a tool has been developed which employs extensions of the Form-Z commercial solid modeling tool. The resultant FZ2MC (Form-Z to Monte Carlo) tool permits users to create, modify and validate Monte Carlo geometry and material composition input data. Plugin modules that export this data to an input file, as well as parse data from existing input files, have been developed for several Monte Carlo codes. The FZ2MC tool is envisioned as a 'universal' tool for the manipulation of Monte Carlo geometry and material data. To this end, collaboration on the development of plug-in modules for additional Monte Carlo codes is desired.
Properties of Reactive Oxygen Species by Quantum Monte Carlo
Andrea Zen; Bernhardt L. Trout; Leonardo Guidoni
2014-06-16T23:59:59.000Z
The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of Chemistry, Biology and Atmospheric Science. Nevertheless, the electronic structure of such species is a challenge for ab-initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as $N^3-N^4$, where $N$ is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.
Global neutrino parameter estimation using Markov Chain Monte Carlo
Steen Hannestad
2007-10-10T23:59:59.000Z
We present a Markov Chain Monte Carlo global analysis of neutrino parameters using both cosmological and experimental data. Results are presented for the combination of all presently available data from oscillation experiments, cosmology, and neutrinoless double beta decay. In addition we explicitly study the interplay between cosmological, tritium decay and neutrinoless double beta decay data in determining the neutrino mass parameters. We furthermore discuss how the inference of non-neutrino cosmological parameters can benefit from future neutrino mass experiments such as the KATRIN tritium decay experiment or neutrinoless double beta decay experiments.
Markov Chain Monte Carlo Method without Detailed Balance
Hidemaro Suwa; Synge Todo
2010-10-13T23:59:59.000Z
We present a specific algorithm that generally satisfies the balance condition without imposing the detailed balance in the Markov chain Monte Carlo. In our algorithm, the average rejection rate is minimized, and even reduced to zero in many relevant cases. The absence of the detailed balance also introduces a net stochastic flow in a configuration space, which further boosts up the convergence. We demonstrate that the autocorrelation time of the Potts model becomes more than 6 times shorter than that by the conventional Metropolis algorithm. Based on the same concept, a bounce-free worm algorithm for generic quantum spin models is formulated as well.
Validation of Phonon Physics in the CDMS Detector Monte Carlo
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.
2012-06-06T23:59:59.000Z
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.
Monte Carlo beam capture and charge breeding simulation
Kim, J.S.; Liu, C.; Edgell, D.H.; Pardo, R. [FAR-TECH, Inc., 10350 Science Center Drive, San Diego, California 92121 (United States); FAR-TECH, Inc., 10350 Science Center Drive, San Diego, California 92121 (United States) and University of Rochester, Rochester, New York (United States); Argonne National Laboratory, Argonne, Illinois (United States)
2006-03-15T23:59:59.000Z
A full six-dimensional (6D) phase space Monte Carlo beam capture charge-breeding simulation code examines the beam capture processes of singly charged ion beams injected to an electron cyclotron resonance (ECR) charge breeder from entry to exit. The code traces injected beam ions in an ECR ion source (ECRIS) plasma including Coulomb collisions, ionization, and charge exchange. The background ECRIS plasma is modeled within the current frame work of the generalized ECR ion source model. A simple sample case of an oxygen background plasma with an injected Ar +1 ion beam produces lower charge breeding efficiencies than experimentally obtained. Possible reasons for discrepancies are discussed.
Quantitative Monte Carlo-based holmium-166 SPECT reconstruction
Elschot, Mattijs; Smits, Maarten L. J.; Nijsen, Johannes F. W.; Lam, Marnix G. E. H.; Zonnenberg, Bernard A.; Bosch, Maurice A. A. J. van den; Jong, Hugo W. A. M. de [Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Viergever, Max A. [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)] [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)
2013-11-15T23:59:59.000Z
Purpose: Quantitative imaging of the radionuclide distribution is of increasing interest for microsphere radioembolization (RE) of liver malignancies, to aid treatment planning and dosimetry. For this purpose, holmium-166 ({sup 166}Ho) microspheres have been developed, which can be visualized with a gamma camera. The objective of this work is to develop and evaluate a new reconstruction method for quantitative {sup 166}Ho SPECT, including Monte Carlo-based modeling of photon contributions from the full energy spectrum.Methods: A fast Monte Carlo (MC) simulator was developed for simulation of {sup 166}Ho projection images and incorporated in a statistical reconstruction algorithm (SPECT-fMC). Photon scatter and attenuation for all photons sampled from the full {sup 166}Ho energy spectrum were modeled during reconstruction by Monte Carlo simulations. The energy- and distance-dependent collimator-detector response was modeled using precalculated convolution kernels. Phantom experiments were performed to quantitatively evaluate image contrast, image noise, count errors, and activity recovery coefficients (ARCs) of SPECT-fMC in comparison with those of an energy window-based method for correction of down-scattered high-energy photons (SPECT-DSW) and a previously presented hybrid method that combines MC simulation of photopeak scatter with energy window-based estimation of down-scattered high-energy contributions (SPECT-ppMC+DSW). Additionally, the impact of SPECT-fMC on whole-body recovered activities (A{sup est}) and estimated radiation absorbed doses was evaluated using clinical SPECT data of six {sup 166}Ho RE patients.Results: At the same noise level, SPECT-fMC images showed substantially higher contrast than SPECT-DSW and SPECT-ppMC+DSW in spheres ?17 mm in diameter. The count error was reduced from 29% (SPECT-DSW) and 25% (SPECT-ppMC+DSW) to 12% (SPECT-fMC). ARCs in five spherical volumes of 1.96–106.21 ml were improved from 32%–63% (SPECT-DSW) and 50%–80% (SPECT-ppMC+DSW) to 76%–103% (SPECT-fMC). Furthermore, SPECT-fMC recovered whole-body activities were most accurate (A{sup est}= 1.06 × A ? 5.90 MBq, R{sup 2}= 0.97) and SPECT-fMC tumor absorbed doses were significantly higher than with SPECT-DSW (p = 0.031) and SPECT-ppMC+DSW (p = 0.031).Conclusions: The quantitative accuracy of {sup 166}Ho SPECT is improved by Monte Carlo-based modeling of the image degrading factors. Consequently, the proposed reconstruction method enables accurate estimation of the radiation absorbed dose in clinical practice.
Monte Sereno, California: Energy Resources | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaPLawrence County,1980) | Open EnergyMonetta, SouthMontana CodeOpenOpen(Redirected fromMontauk,Monte
Monte Carlo Tools for charged Higgs boson production
K. Kovarik
2014-12-18T23:59:59.000Z
In this short review we discuss two implementations of the charged Higgs boson production process in association with a top quark in Monte Carlo event generators at next-to-leading order in QCD. We introduce the MC@NLO and the POWHEG method of matching next-to-leading order matrix elements with parton showers and compare both methods analyzing the charged Higgs boson production process in association with a top quark. We shortly discuss the case of a light charged Higgs boson where the associated charged Higgs production interferes with the charged Higgs production via t tbar-production and subsequent decay of the top quark.
Electron scattering in helium for Monte Carlo simulations
Khrabrov, Alexander V.; Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2012-09-15T23:59:59.000Z
An analytical approximation for differential cross-section of electron scattering on helium atoms is introduced. It is intended for Monte Carlo simulations, which, instead of angular distributions based on experimental data (or on first-principle calculations), usually rely on approximations that are accurate yet numerically efficient. The approximation is based on the screened-Coulomb differential cross-section with energy-dependent screening. For helium, a two-pole approximation of the screening parameter is found to be highly accurate over a wide range of energies.
Monte Carlo tests of Orbital-Free Density Functional Theory
D. I. Palade
2014-12-12T23:59:59.000Z
The relationship between the exact kinetic energy density in a quantum system in the frame of Density Functional Theory and the semiclassical functional expression for the same quantity is investigated. The analysis is performed with Monte Carlo simulations of the Kohn-Sham potentials. We find that the semiclassical form represents the statistical expectation value of the quantum nature. Based on the numerical results, we propose an empirical correction to the existing functional and an associated method to improve the Orbital-Free results.
A Look at general cavity theory through a code incorporating Monte Carlo techniques
Weyland, Mark Duffy
1989-01-01T23:59:59.000Z
material, the wall, being exponentially attenuated into the dosimeter, or the cavity. This assumption was investigated in this research using the Monte Carlo techniques in a modern computer code EGS4, Appropriate geometries were defined in the code and a... and relate the measured dose to that within the material, Monte Carlo techniques have been used to simulate the irradiation of various materials. The computer code EGS4 uses Monte Carlo techniques to simulate the randomness of radiation interactions...
Four-quark energies in SU(2) lattice Monte Carlo using a tetrahedral geometry
A. M. Green; J. Lukkarinen; P. Pennanen; C. Michael; S. Furui
1994-12-05T23:59:59.000Z
This contribution -- a continuation of earlier work -- reports on recent developments in the calculation and understanding of 4-quark energies generated using lattice Monte Carlo techniques.
Monte Carlo radiative heat transfer simulation on a reconfigurable computer
Gokhale, M. (Maya); Ahrens, C. M. (Christine Marie); Frigo, J. (Janette); Minnich, R. G. (Ronald G.); Tripp J. L. (Justin L.)
2004-01-01T23:59:59.000Z
Recently, the appearance of very large (3-10M gate) FPGAs with embedded arithmetic units has opened the door to the possibility of floating point computation on these devices. While previous researchers have described peak performance or kernel matrix operations, there is as yet little experience with mapping an application-specific floating point pipeline onto FPGAs. In this work, we port a supercomputer application benchmark onto Xilinx Virtex II and II Pro FPGAs and compare performance with comparable microprocessor implementation. Our results show that this application-specific pipeline, with 12 multiply, 10 add/subtract, one divide, and two compare modules of single precision floating point data type, shows speedup of 1.6x-1.7x. We analyze the trade-offs between hardware and software 'sweet spots' to characterize the algorithms that will perform well on current and future FPGA architectures.
Monte Carlo simulation of quantum Zeno effect in the brain
Danko Georgiev
2014-12-11T23:59:59.000Z
Environmental decoherence appears to be the biggest obstacle for successful construction of quantum mind theories. Nevertheless, the quantum physicist Henry Stapp promoted the view that the mind could utilize quantum Zeno effect to influence brain dynamics and that the efficacy of such mental efforts would not be undermined by environmental decoherence of the brain. To address the physical plausibility of Stapp's claim, we modeled the brain using quantum tunneling of an electron in a multiple-well structure such as the voltage sensor in neuronal ion channels and performed Monte Carlo simulations of quantum Zeno effect exerted by the mind upon the brain in the presence or absence of environmental decoherence. The simulations unambiguously showed that the quantum Zeno effect breaks down for timescales greater than the brain decoherence time. To generalize the Monte Carlo simulation results for any n-level quantum system, we further analyzed the change of brain entropy due to the mind probing actions and proved a theorem according to which local projections cannot decrease the von Neumann entropy of the unconditional brain density matrix. The latter theorem establishes that Stapp's model is physically implausible but leaves a door open for future development of quantum mind theories provided the brain has a decoherence-free subspace.
Monte Carlo model for electron degradation in methane
Bhardwaj, Anil
2015-01-01T23:59:59.000Z
We present a Monte Carlo model for degradation of 1-10,000 eV electrons in an atmosphere of methane. The electron impact cross sections for CH4 are compiled and analytical representations of these cross sections are used as input to the model.model.Yield spectra, which provides information about the number of inelastic events that have taken place in each energy bin, is used to calculate the yield (or population) of various inelastic processes. The numerical yield spectra, obtained from the Monte Carlo simulations, is represented analytically, thus generating the Analytical Yield Spectra (AYS). AYS is employed to obtain the mean energy per ion pair and efficiencies of various inelastic processes.Mean energy per ion pair for neutral CH4 is found to be 26 (27.8) eV at 10 (0.1) keV. Efficiency calculation showed that ionization is the dominant process at energies >50 eV, for which more than 50% of the incident electron energy is used. Above 25 eV, dissociation has an efficiency of 27%. Below 10 eV, vibrational e...
Khodabakhshi, F.; Kazeminezhad, M., E-mail: mkazemi@sharif.edu; Kokabi, A.H.
2012-07-15T23:59:59.000Z
Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel sheets. The ultra-fine grained sheets are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the sheets with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained sheet spot welds have been investigated in the present paper and the welding current and time of resistance spot welding process according to these subjects are optimized. Failure mode and failure load obtained in tensile-shear test, microhardness, X-ray diffraction, transmission electron microscope and scanning electron microscope images have been used to describe the performance of spot welds. The region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. The results show that optimum welding parameters (welding current and welding time) for ultra-fine grained sheets are shifted to lower values with respect to those for as-received specimens. In ultra-fine grained sheets, one new region is formed named recrystallized zone in addition to fusion zone, heat affected zone and base metal. It is shown that microstructures of different zones in ultra-fine grained sheets are finer than those of as-received sheets. - Highlights: Black-Right-Pointing-Pointer Resistance spot welding process is optimized for joining of UFG steel sheets. Black-Right-Pointing-Pointer Optimum welding current and time are decreased with increasing the CGP pass number. Black-Right-Pointing-Pointer Microhardness at BM, HAZ, FZ and recrystallized zone is enhanced due to CGP.
Control of Black Spot of Roses with Sulphur-Copper Dust.
Lyle, E. W. (Eldon W.)
1944-01-01T23:59:59.000Z
-type hand duster. Later a Root Model C2 "Challenge" hand-crank, rotary duster was used in large plots. Accu- rate records of the actual amounts of dust applied were kept by weighing the duster and fungicide before and after each treatment. In some cases... STATION A. B. CONNER, Director College Station, Texas BULLETIN NO. 648 APRIL, 1944 CONTROL OF BLACK SPOT OF ROSES WITH SULPHUR-COPPER DUST E. W. LYLE Division of Plant Pathology and Physiology l ,i- ' 7, r - . /.~ric[~i L~jj c,, J: . i...
The LaueUtil toolkit for Laue photocrystallography. II. Spot finding and integration
Kalinowski, Jaroslaw A.; Fournier, Bertrand; Makal, Anna; Coppens, Philip (SUNYB); (LBNL)
2012-09-11T23:59:59.000Z
A spot-integration method is described which does not require prior indexing of the reflections. It is based on statistical analysis of the values from each of the pixels on successive frames, followed for each frame by morphological analysis to identify clusters of high value pixels which form an appropriate mask corresponding to a reflection peak. The method does not require prior assumptions such as fitting of a profile or definition of an integration box. The results are compared with those of the seed-skewness method which is based on minimizing the skewness of the intensity distribution within a peak's integration box. Applications in Laue photocrystallography are presented.
Numerical studies of third-harmonic generation in laser filament in air perturbed by plasma spot
Feng Liubin [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190 (China); Institute of Atomic and Molecular Physics and Department of Physics, Sichuan University, Chengdu 610065 (China); Lu Xin; Liu Xiaolong; Li Yutong; Chen Liming; Ma Jinglong; Dong Quanli; Wang Weimin [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190 (China); Xi Tingting [College of Physical Sciences, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Sheng Zhengming; Zhang Jie [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190 (China); Key Laboratory for Laser Plasmas of the Ministry of Education of China and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); He Duanwei [Institute of Atomic and Molecular Physics and Department of Physics, Sichuan University, Chengdu 610065 (China)
2012-07-15T23:59:59.000Z
Third-harmonic emission from laser filament intercepted by plasma spot is studied by numerical simulations. Significant enhancement of the third-harmonic generation is obtained due to the disturbance of the additional plasma. The contribution of the pure plasma effect and the possible plasma-enhanced third-order susceptibility on the third-harmonic generation enhancement are compared. It is shown that the plasma induced cancellation of destructive interference [Y. Liu et al., Opt. Commun. 284, 4706 (2011)] of two-colored filament is the dominant mechanism of the enhancement of third-harmonic generation.
Ellison, Chad M. (Honeywell FM& T, Kansas City, MO); Perricone, Matthew J. (R.J. Lee Group, Inc., Monroeville, PA); Faraone, Kevin M. (BWX Technologies, Inc., Lynchburg, VA); Norris, Jerome T.
2007-10-01T23:59:59.000Z
Weld porosity is being investigated for long-pulse spot welds produced by high power continuous output lasers. Short-pulse spot welds (made with a pulsed laser system) are also being studied but to a much small extent. Given that weld area of a spot weld is commensurate with weld strength, the loss of weld area due to an undefined or unexpected pore results in undefined or unexpected loss in strength. For this reason, a better understanding of spot weld porosity is sought. Long-pulse spot welds are defined and limited by the slow shutter speed of most high output power continuous lasers. Continuous lasers typically ramp up to a simmer power before reaching the high power needed to produce the desired weld. A post-pulse ramp down time is usually present as well. The result is a pulse length tenths of a second long as oppose to the typical millisecond regime of the short-pulse pulsed laser. This study will employ a Lumonics JK802 Nd:YAG laser with Super Modulation pulse shaping capability and a Lasag SLS C16 40 W pulsed Nd:YAG laser. Pulse shaping will include square wave modulation of various peak powers for long-pulse welds and square (or top hat) and constant ramp down pulses for short-pulse welds. Characterization of weld porosity will be performed for both pulse welding methods.
Brachytherapy structural shielding calculations using Monte Carlo generated, monoenergetic data
Zourari, K.; Peppa, V.; Papagiannis, P., E-mail: ppapagi@phys.uoa.gr [Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 11527 Athens (Greece); Ballester, Facundo [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain)] [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Siebert, Frank-André [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel 24105 (Germany)] [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel 24105 (Germany)
2014-04-15T23:59:59.000Z
Purpose: To provide a method for calculating the transmission of any broad photon beam with a known energy spectrum in the range of 20–1090 keV, through concrete and lead, based on the superposition of corresponding monoenergetic data obtained from Monte Carlo simulation. Methods: MCNP5 was used to calculate broad photon beam transmission data through varying thickness of lead and concrete, for monoenergetic point sources of energy in the range pertinent to brachytherapy (20–1090 keV, in 10 keV intervals). The three parameter empirical model introduced byArcher et al. [“Diagnostic x-ray shielding design based on an empirical model of photon attenuation,” Health Phys. 44, 507–517 (1983)] was used to describe the transmission curve for each of the 216 energy-material combinations. These three parameters, and hence the transmission curve, for any polyenergetic spectrum can then be obtained by superposition along the lines of Kharrati et al. [“Monte Carlo simulation of x-ray buildup factors of lead and its applications in shielding of diagnostic x-ray facilities,” Med. Phys. 34, 1398–1404 (2007)]. A simple program, incorporating a graphical user interface, was developed to facilitate the superposition of monoenergetic data, the graphical and tabular display of broad photon beam transmission curves, and the calculation of material thickness required for a given transmission from these curves. Results: Polyenergetic broad photon beam transmission curves of this work, calculated from the superposition of monoenergetic data, are compared to corresponding results in the literature. A good agreement is observed with results in the literature obtained from Monte Carlo simulations for the photon spectra emitted from bare point sources of various radionuclides. Differences are observed with corresponding results in the literature for x-ray spectra at various tube potentials, mainly due to the different broad beam conditions or x-ray spectra assumed. Conclusions: The data of this work allow for the accurate calculation of structural shielding thickness, taking into account the spectral variation with shield thickness, and broad beam conditions, in a realistic geometry. The simplicity of calculations also obviates the need for the use of crude transmission data estimates such as the half and tenth value layer indices. Although this study was primarily designed for brachytherapy, results might also be useful for radiology and nuclear medicine facility design, provided broad beam conditions apply.
The Long Memory of Order Flow in the Foreign Exchange Spot Market
Gould, Martin D; Howison, Sam D
2015-01-01T23:59:59.000Z
We study the long memory of order flow for each of three liquid currency pairs on a large electronic trading platform in the foreign exchange (FX) spot market. Due to the extremely high levels of market activity on the platform, and in contrast to existing empirical studies of other markets, our data enables us to perform statistically stable estimation without needing to aggregate data from different trading days. We find strong evidence of long memory, with a Hurst exponent of approximately 0.7, for each of the three currency pairs and on each trading day in our sample. We repeat our calculations using data that spans different trading days, and we find no significant differences in our results. We test and reject the hypothesis that the apparent long memory of order flow is an artefact caused by structural breaks, in favour of the alternative hypothesis of true long memory. We therefore conclude that the long memory of order flow in the FX spot market is a robust empirical property that persists across dai...
Monitoring seasonal and annual wetland changes in a freshwater marsh with SPOT HRV data
Mackey, H.E. Jr.
1989-01-01T23:59:59.000Z
Eleven dates of SPOT HRV data along with near-concurrent vertical aerial photographic and phenological data for 1987, 1988, and 1989 were evaluated to determine seasonal and annual changes in a 400-hectare, southeastern freshwater marsh. Early April through mid-May was the best time to discriminate among the cypress (Taxodium distichum)/water tupelo (Nyssa acquatica) swamp forest and the non-persistent (Ludwigia spp.) and persistent (Typha spp.) stands in this wetlands. Furthermore, a ten-fold decrease in flow rate from 11 cubic meters per sec (cms) in 1987 to one cms in 1988 was recorded in the marsh followed by a shift to drier wetland communities. The Savannah River Site (SRS), maintained by the US Department of Energy, is a 777 km{sup 2} area located in south central South Carolina. Five tributaries of the Savannah River run southwest through the SRS and into the floodplain swamp of the Savannah River. This paper describes the use of SPOT HRV data to monitor seasonal and annual trends in one of these swamp deltas, Pen Branch Delta, during a three-year period, 1987--1989.
Monitoring seasonal and annual wetland changes in a freshwater marsh with SPOT HRV data
Mackey, H.E. Jr.
1989-12-31T23:59:59.000Z
Eleven dates of SPOT HRV data along with near-concurrent vertical aerial photographic and phenological data for 1987, 1988, and 1989 were evaluated to determine seasonal and annual changes in a 400-hectare, southeastern freshwater marsh. Early April through mid-May was the best time to discriminate among the cypress (Taxodium distichum)/water tupelo (Nyssa acquatica) swamp forest and the non-persistent (Ludwigia spp.) and persistent (Typha spp.) stands in this wetlands. Furthermore, a ten-fold decrease in flow rate from 11 cubic meters per sec (cms) in 1987 to one cms in 1988 was recorded in the marsh followed by a shift to drier wetland communities. The Savannah River Site (SRS), maintained by the US Department of Energy, is a 777 km{sup 2} area located in south central South Carolina. Five tributaries of the Savannah River run southwest through the SRS and into the floodplain swamp of the Savannah River. This paper describes the use of SPOT HRV data to monitor seasonal and annual trends in one of these swamp deltas, Pen Branch Delta, during a three-year period, 1987--1989.
DEFINING THE 'BLIND SPOT' OF HINODE EIS AND XRT TEMPERATURE MEASUREMENTS
Winebarger, Amy R.; Cirtain, Jonathan; Mulu-Moore, Fana [NASA Marshall Space Flight Center, VP 62, Huntsville, AL 35812 (United States); Warren, Harry P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Schmelz, Joan T. [Physics Department, University of Memphis, Memphis, TN 38152 (United States); Golub, Leon [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Kobayashi, Ken, E-mail: amy.r.winebarger@nasa.gov [Center for Space Plasma and Aeronomic Research, 320 Sparkman Dr, Huntsville, AL 35805 (United States)
2012-02-20T23:59:59.000Z
Observing high-temperature, low emission measure plasma is key to unlocking the coronal heating problem. With current instrumentation, a combination of EUV spectral data from Hinode Extreme-ultraviolet Imaging Spectrometer (EIS; sensitive to temperatures up to 4 MK) and broadband filter data from Hinode X-ray Telescope (XRT; sensitive to higher temperatures) is typically used to diagnose the temperature structure of the observed plasma. In this Letter, we demonstrate that a 'blind spot' exists in temperature-emission measure space for combined Hinode EIS and XRT observations. For a typical active region core with significant emission at 3-4 MK, Hinode EIS and XRT are insensitive to plasma with temperatures greater than {approx}6 MK and emission measures less than {approx}10{sup 27} cm{sup -5}. We then demonstrate that the temperature and emission measure limits of this blind spot depend upon the temperature distribution of the plasma along the line of sight by considering a hypothetical emission measure distribution sharply peaked at 1 MK. For this emission measure distribution, we find that EIS and XRT are insensitive to plasma with emission measures less than {approx}10{sup 26} cm{sup -5}. We suggest that a spatially and spectrally resolved 6-24 Angstrom-Sign spectrum would improve the sensitivity to these high-temperature, low emission measure plasma.
Schulze, Tim
An Energy Localization Principle and its Application to Fast Kinetic Monte Carlo Simulation of Michigan, Ann Arbor, MI 48109-1109 Abstract Simulation of heteroepitaxial growth using kinetic Monte Carlo (KMC) is often based on rates determined by differences in elastic energy between two configurations
MONTE CARLO SIMULATION METHOD By Ronald R. Charpentier and Timothy R. Klett
Laughlin, Robert B.
EMCEE and Emc2 are Monte-Carlo simulation programs for assessing undiscovered conventional oil and gasChapter MC MONTE CARLO SIMULATION METHOD By Ronald R. Charpentier and Timothy R. Klett in U in the toolbar to return. U.S. GEOLOGICAL SURVEY WORLD PETROLEUM ASSESSMENT 2000-- DESCRIPTION AND RESULTS U
Author's personal copy Monte Carlo methods for design and analysis of radiation detectors
Shultis, J. Kenneth
Author's personal copy Monte Carlo methods for design and analysis of radiation detectors William L Radiation detectors Inverse problems Detector design a b s t r a c t An overview of Monte Carlo as a practical method for designing and analyzing radiation detectors is provided. The emphasis is on detectors
BAYESIAN INFERENCE FOR MODELS OF TRANSCRIPTIONAL REGULATION USING MARKOV CHAIN MONTE CARLO SAMPLING
Opper, Manfred
]. In this contribution we present a Markov chain Monte Carlo (MCMC) sampler which infers the TF activity based on a modelBAYESIAN INFERENCE FOR MODELS OF TRANSCRIPTIONAL REGULATION USING MARKOV CHAIN MONTE CARLO SAMPLING]. Transcription of genes is controlled by proteins which can bind to particular base-sequences of DNA
Direct Monte Carlo simulation of chemical reaction systems: Simple bimolecular reactions
Anderson, James B.
Direct Monte Carlo simulation of chemical reaction systems: Simple bimolecular reactions Shannon D and understanding the behavior of gas phase chemical reaction systems. This Monte Carlo method, originated by Bird. Extension to chemical reactions offers a powerful tool for treating reaction systems with nonthermal
A New Monte Carlo Simulation Method for Tolerance Analysis of Kinematically Constrained Assemblies
A New Monte Carlo Simulation Method for Tolerance Analysis of Kinematically Constrained Assemblies Abstract A generalized Monte Carlo simulation method is presented for tolerance analysis of mechanical assemblies with small kinematic adjustments. This is a new tool for assembly tolerance analysis based
Path Integral Monte Carlo Calculation of the Deuterium Hugoniot B. Militzer and D. M. Ceperley
Militzer, Burkhard
Path Integral Monte Carlo Calculation of the Deuterium Hugoniot B. Militzer and D. M. Ceperley-Champaign, Urbana, IL 61801 (January 21, 2000) Restricted path integral Monte Carlo simulations have been used#11;ects and the dependence on the time step of the path integral. Further, we compare the results
Continuous Contour Monte Carlo for Marginal Density Estimation With an Application to a
Liang, Faming
; Gelman and Meng 1998), reverse logistic regression (Geyer 1994), marginal likelihood (Chib 1995; Chib; Reversible jump Markov chain Monte Carlo; Stochastic approximation; Wang-Landau algorithm. 1. INTRODUCTION;Continuous Contour Monte Carlo 609 variety of approaches including reversible jump MCMC (Green 1995; Green
Kinetic Monte Carlo simulations of the response of carbon nanotubes to electron irradiation
Krasheninnikov, Arkady V.
Kinetic Monte Carlo simulations of the response of carbon nanotubes to electron irradiation J of Technology, Finland (Dated: January 12, 2007) Irradiation is increasingly used nowadays to tailor of nanotubes to irradiation is still lacking, we have implemented the kinetic Monte Carlo method with Bortz
Population Monte Carlo algorithms Yukito Iba The Institute of Statistical Mathematics
Iba, Yukito
279 ¤ Population Monte Carlo algorithms Yukito Iba The Institute of Statistical Mathematics iba algorithm Summary 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
Hybrid Probabilistic RoadMap -Monte Carlo Motion Planning for Closed Chain Systems with
Han, Li
Hybrid Probabilistic RoadMap - Monte Carlo Motion Planning for Closed Chain Systems with Spherical@clarku.edu Abstract-- In this paper we propose a hybrid Probabilistic RoadMap - Monte Carlo (PRM-MC) motion planner and connect a large number of robot configurations in order to build a roadmap that reflects the properties
Benmakhlouf, Hamza, E-mail: hamza.benmakhlouf@karolinska.se [Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden, and Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)] [Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden, and Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden); Sempau, Josep [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Diagonal 647, E-08028, Barcelona (Spain)] [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Diagonal 647, E-08028, Barcelona (Spain); Andreo, Pedro [Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)] [Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)
2014-04-15T23:59:59.000Z
Purpose: To determine detector-specific output correction factors,k{sub Q} {sub c{sub l{sub i{sub n}}}} {sub ,Q} {sub m{sub s{sub r}}} {sup f{sub {sup {sub c}{sub l}{sub i}{sub n}{sub {sup ,f{sub {sup {sub m}{sub s}{sub r}{sub ,}}}}}}}} in 6 MV small photon beams for air and liquid ionization chambers, silicon diodes, and diamond detectors from two manufacturers. Methods: Field output factors, defined according to the international formalism published byAlfonso et al. [Med. Phys. 35, 5179–5186 (2008)], relate the dosimetry of small photon beams to that of the machine-specific reference field; they include a correction to measured ratios of detector readings, conventionally used as output factors in broad beams. Output correction factors were calculated with the PENELOPE Monte Carlo (MC) system with a statistical uncertainty (type-A) of 0.15% or lower. The geometries of the detectors were coded using blueprints provided by the manufacturers, and phase-space files for field sizes between 0.5 × 0.5 cm{sup 2} and 10 × 10 cm{sup 2} from a Varian Clinac iX 6 MV linac used as sources. The output correction factors were determined scoring the absorbed dose within a detector and to a small water volume in the absence of the detector, both at a depth of 10 cm, for each small field and for the reference beam of 10 × 10 cm{sup 2}. Results: The Monte Carlo calculated output correction factors for the liquid ionization chamber and the diamond detector were within about ±1% of unity even for the smallest field sizes. Corrections were found to be significant for small air ionization chambers due to their cavity dimensions, as expected. The correction factors for silicon diodes varied with the detector type (shielded or unshielded), confirming the findings by other authors; different corrections for the detectors from the two manufacturers were obtained. The differences in the calculated factors for the various detectors were analyzed thoroughly and whenever possible the results were compared to published data, often calculated for different accelerators and using the EGSnrc MC system. The differences were used to estimate a type-B uncertainty for the correction factors. Together with the type-A uncertainty from the Monte Carlo calculations, an estimation of the combined standard uncertainty was made, assigned to the mean correction factors from various estimates. Conclusions: The present work provides a consistent and specific set of data for the output correction factors of a broad set of detectors in a Varian Clinac iX 6 MV accelerator and contributes to improving the understanding of the physics of small photon beams. The correction factors cannot in general be neglected for any detector and, as expected, their magnitude increases with decreasing field size. Due to the reduced number of clinical accelerator types currently available, it is suggested that detector output correction factors be given specifically for linac models and field sizes, rather than for a beam quality specifier that necessarily varies with the accelerator type and field size due to the different electron spot dimensions and photon collimation systems used by each accelerator model.
Monte Carlo Simulation of Dense Polymer Melts Using Event Chain Algorithms
Tobias Alexander Kampmann; Horst-Holger Boltz; Jan Kierfeld
2015-07-23T23:59:59.000Z
We propose an efficient Monte Carlo algorithm for the off-lattice simulation of dense hard sphere polymer melts using cluster moves, called event chains, which allow for a rejection-free treatment of the excluded volume. Event chains also allow for an efficient preparation of initial configurations in polymer melts. We parallelize the event chain Monte Carlo algorithm to further increase simulation speeds and suggest additional local topology-changing moves ("swap" moves) to accelerate equilibration. By comparison with other Monte Carlo and molecular dynamics simulations, we verify that the event chain algorithm reproduces the correct equilibrium behavior of polymer chains in the melt. By comparing intrapolymer diffusion time scales, we show that event chain Monte Carlo algorithms can achieve simulation speeds comparable to optimized molecular dynamics simulations. The event chain Monte Carlo algorithm exhibits Rouse dynamics on short time scales. In the absence of swap moves, we find reptation dynamics on intermediate time scales for long chains.
SKIRT: the design of a suite of input models for Monte Carlo radiative transfer simulations
Baes, Maarten
2015-01-01T23:59:59.000Z
The Monte Carlo method is the most popular technique to perform radiative transfer simulations in a general 3D geometry. The algorithms behind and acceleration techniques for Monte Carlo radiative transfer are discussed extensively in the literature, and many different Monte Carlo codes are publicly available. On the contrary, the design of a suite of components that can be used for the distribution of sources and sinks in radiative transfer codes has received very little attention. The availability of such models, with different degrees of complexity, has many benefits. For example, they can serve as toy models to test new physical ingredients, or as parameterised models for inverse radiative transfer fitting. For 3D Monte Carlo codes, this requires algorithms to efficiently generate random positions from 3D density distributions. We describe the design of a flexible suite of components for the Monte Carlo radiative transfer code SKIRT. The design is based on a combination of basic building blocks (which can...
Single temperature for Monte Carlo optimization on complex landscapes
Tolkunov, Denis
2012-01-01T23:59:59.000Z
We propose a new strategy for Monte Carlo (MC) optimization on rugged multidimensional landscapes. The strategy is based on querying the statistical properties of the landscape in order to find the temperature at which the mean first passage time across the current region of the landscape is minimized. Thus, in contrast to other algorithms such as simulated annealing (SA), we explicitly match the temperature schedule to the statistics of landscape irregularities. In cases where this statistics is approximately the same over the entire landscape, or where non-local moves couple distant parts of the landscape, single-temperature MC will outperform any other MC algorithm with the same move set. We also find that in strongly anisotropic Coulomb spin glass and traveling salesman problems, the only relevant statistics (which we use to assign a single MC temperature) is that of irregularities in low-energy funnels. Our results may explain why protein folding in nature is efficient at room temperatures.
Monte Carlo Simulation Tool Installation and Operation Guide
Aguayo Navarrete, Estanislao; Ankney, Austin S.; Berguson, Timothy J.; Kouzes, Richard T.; Orrell, John L.; Troy, Meredith D.; Wiseman, Clinton G.
2013-09-02T23:59:59.000Z
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.
Improving multivariate Horner schemes with Monte Carlo tree search
J. Kuipers; J. A. M. Vermaseren; A. Plaat; H. J. van den Herik
2012-07-30T23:59:59.000Z
Optimizing the cost of evaluating a polynomial is a classic problem in computer science. For polynomials in one variable, Horner's method provides a scheme for producing a computationally efficient form. For multivariate polynomials it is possible to generalize Horner's method, but this leaves freedom in the order of the variables. Traditionally, greedy schemes like most-occurring variable first are used. This simple textbook algorithm has given remarkably efficient results. Finding better algorithms has proved difficult. In trying to improve upon the greedy scheme we have implemented Monte Carlo tree search, a recent search method from the field of artificial intelligence. This results in better Horner schemes and reduces the cost of evaluating polynomials, sometimes by factors up to two.
The Quantum Energy Density: Improved Efficiency for Quantum Monte Carlo
Krogel, Jaron T; Kim, Jeongnim; Ceperley, David M
2013-01-01T23:59:59.000Z
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.
Strain in the mesoscale kinetic Monte Carlo model for sintering
Bjørk, R; Tikare, V; Olevsky, E; Pryds, N
2014-01-01T23:59:59.000Z
Shrinkage strains measured from microstructural simulations using the mesoscale kinetic Monte Carlo (kMC) model for solid state sintering are discussed. This model represents the microstructure using digitized discrete sites that are either grain or pore sites. The algorithm used to simulate densification by vacancy annihilation removes an isolated pore site at a grain boundary and collapses a column of sites extending from the vacancy to the surface of sintering compact, through the center of mass of the nearest grain. Using this algorithm, the existing published kMC models are shown to produce anisotropic strains for homogeneous powder compacts with aspect ratios different from unity. It is shown that the line direction biases shrinkage strains in proportion the compact dimension aspect ratios. A new algorithm that corrects this bias in strains is proposed; the direction for collapsing the column is determined by choosing a random sample face and subsequently a random point on that face as the end point for...
Peelle's pertinent puzzle using the Monte Carlo technique
Kawano, Toshihiko [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory; Burr, Thomas [Los Alamos National Laboratory; Pan, Feng [Los Alamos National Laboratory
2009-01-01T23:59:59.000Z
We try to understand the long-standing problem of the Peelle's Pertinent Puzzle (PPP) using the Monte Carlo technique. We allow the probability density functions to be any kind of form to assume the impact of distribution, and obtain the least-squares solution directly from numerical simulations. We found that the standard least squares method gives the correct answer if a weighting function is properly provided. Results from numerical simulations show that the correct answer of PPP is 1.1 {+-} 0.25 if the common error is multiplicative. The thought-provoking answer of 0.88 is also correct, if the common error is additive, and if the error is proportional to the measured values. The least squares method correctly gives us the most probable case, where the additive component has a negative value. Finally, the standard method fails for PPP due to a distorted (non Gaussian) joint distribution.
Lifting -- A Nonreversible Markov Chain Monte Carlo Algorithm
Vucelja, Marija
2015-01-01T23:59:59.000Z
Markov Chain Monte Carlo algorithms are invaluable numerical tools for exploring stationary properties of physical systems -- in particular when direct sampling is not feasible. They are widely used in many areas of physics and other sciences. Most common implementations are done with reversible Markov chains -- Markov chains that obey detailed balance. Reversible Markov chains are sufficient in order for the physical system to relax to equilibrium, but it is not necessary. Here we review several works that use "lifted" or nonreversible Markov chains, which violate detailed balance, yet still converge to the correct stationary distribution (they obey the global balance condition). In certain cases, the acceleration is a square root improvement at most, to the conventional reversible Markov chains. We introduce the problem in a way that makes it accessible to non-specialists. We illustrate the method on several representative examples (sampling on a ring, sampling on a torus, an Ising model on a complete graph...
The neutron instrument Monte Carlo library MCLIB: Recent developments
Seeger, P.A.; Daemen, L.L.; Hjelm, R.P. Jr.; Thelliez, T.G.
1998-12-31T23:59:59.000Z
A brief review is given of the developments since the ICANS-XIII meeting made in the neutron instrument design codes using the Monte Carlo library MCLIB. Much of the effort has been to assure that the library and the executing code MC{_}RUN connect efficiently with the World Wide Web application MC-WEB as part of the Los Alamos Neutron Instrument Simulation Package (NISP). Since one of the most important features of MCLIB is its open structure and capability to incorporate any possible neutron transport or scattering algorithm, this document describes the current procedure that would be used by an outside user to add a feature to MCLIB. Details of the calling sequence of the core subroutine OPERATE are discussed, and questions of style are considered and additional guidelines given. Suggestions for standardization are solicited, as well as code for new algorithms.
Hybrid Monte Carlo simulation on the graphene hexagonal lattice
Richard Brower; Claudio Rebbi; David Schaich
2012-04-24T23:59:59.000Z
One of the many remarkable properties of graphene is that in the low energy limit the dynamics of its electrons can be effectively described by the massless Dirac equation. This has prompted investigations of graphene based on the lattice simulation of a system of 2-dimensional fermions on a square staggered lattice. We demonstrate here how to construct the path integral for graphene working directly on the graphene hexagonal lattice. For the nearest neighbor tight binding model interacting with a long range Coulomb interaction between the electrons, this leads to the hybrid Monte Carlo algorithm with no sign problem. The only approximation is the discretization of the Euclidean time. So as we extrapolate to the time continuum limit, the exact tight binding solution maybe found numerically to arbitrary precession on a finite hexagonal lattice. The potential for this approach is tested on a single hexagonal cell.
Improved version of the PHOBOS Glauber Monte Carlo
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Loizides, C.; Nagle, J.; Steinberg, P.
2015-09-01T23:59:59.000Z
“Glauber” models are used to calculate geometric quantities in the initial state of heavy ion collisions, such as impact parameter, number of participating nucleons and initial eccentricity. Experimental heavy-ion collaborations, in particular at RHIC and LHC, use Glauber Model calculations for various geometric observables for determination of the collision centrality. In this document, we describe the assumptions inherent to the approach, and provide an updated implementation (v2) of the Monte Carlo based Glauber Model calculation, which originally was used by the PHOBOS collaboration. The main improvement w.r.t. the earlier version (v1) (Alver et al. 2008) is the inclusion of Tritium,more »Helium-3, and Uranium, as well as the treatment of deformed nuclei and Glauber–Gribov fluctuations of the proton in p +A collisions. A users’ guide (updated to reflect changes in v2) is provided for running various calculations.« less
Quality assurance for the ALICE Monte Carlo procedure
M. Ajaz; Seforo Mohlalisi; Peter Hristov; Jean Pierre Revol
2009-04-10T23:59:59.000Z
We implement the already existing macro,$ALICE_ROOT/STEER /CheckESD.C that is ran after reconstruction to compute the physics efficiency, as a task that will run on proof framework like CAF. The task was implemented in a C++ class called AliAnalysisTaskCheckESD and it inherits from AliAnalysisTaskSE base class. The function of AliAnalysisTaskCheckESD is to compute the ratio of the number of reconstructed particles to the number of particle generated by the Monte Carlo generator.The class AliAnalysisTaskCheckESD was successfully implemented. It was used during the production for first physics and permitted to discover several problems (missing track in the MUON arm reconstruction, low efficiency in the PHOS detector etc.). The code is committed to the SVN repository and will become standard tool for quality assurance.
Koh, Wonshill
2013-02-22T23:59:59.000Z
The light propagation in highly scattering turbid media composed of the particles with different size distribution is studied using a Monte Carlo simulation model implemented in Standard C. Monte Carlo method has been widely utilized to study...
Komarov, V M; Charukhchev, A V [Public Limited Company "Scientific research Institute for Optoelectronic Instrument Engineering", Leningrad region (Russian Federation); Andreev, A A; Platonov, K Yu [Federal State Unitary Enterprise All-Russian Scientific Center "S.I.Vavilov State Optical Institute" (FSUE GOI), St.Petersburg (Russian Federation)
2014-12-31T23:59:59.000Z
We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10{sup 18} W cm{sup -2}. Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)
Straub, John E.
Statistical-Temperature Monte Carlo and Molecular Dynamics Algorithms Jaegil Kim,* John E. Straub. A novel molecular dynamics algorithm (STMD) applicable to complex systems and a Monte Carlo algorithmRevLett.97.050601 PACS numbers: 05.10.ÿa, 02.70.Rr, 87.18.Bb The Wang-Landau (WL) Monte Carlo (MC) algorithm
Using Stochastic Discounted Cash Flow and Real Option Monte Carlo Simulation to Analyse the Impacts in the presence of a windfall profits tax. Real options Monte Carlo simulation is used to characterise from the project. The results highlight that Monte Carlo simulation paired with the real option
Ultrasonic Spot Welding of AZ31B to Galvanized Mild Steel
Pan, Dr. Tsung-Yu [Ford Motor Company; Franklin, Teresa [University of Michigan; Pan, Professor Jwo [University of Michigan; Brown, Elliot [EB Scientific; Santella, Michael L [ORNL
2010-01-01T23:59:59.000Z
Ultrasonic spot welds were made between sheets of 0.8-mm-thick hot-dip-galvanized mild steel and 1.6-mm-thick AZ31B-H24. Lap-shear strengths of 3.0-4.2 kN were achieved with weld times of 0.3-1.2 s. Failure to achieve strong bonding of joints where the Zn coating was removed from the steel surface indicate that Zn is essential to the bonding mechanism. Microstructure characterization and microchemical analysis indicated temperatures at the AZ31-steel interfaces reached at least 344 C in less than 0.3 s. The elevated temperature conditions promoted annealing of the AZ31-H24 metal and chemical reactions between it and the Zn coating.
An investigation of the areal sweep efficiency of the developed five-spot well pattern
Edman, William Douglas
1965-01-01T23:59:59.000Z
(x+bx. y, t+bt))eD(x, y, t). (4) where A=1. 0 B s -(2+ y) C= i. o D(x) = -(P(x, y-Ay, t) - (2- y )P(x, y, t)+ P(x, y, tfty t)). Equation (4) is written for each grid point in a particular row. The pressure at each grid point at time (the...?"' sly it& +be io]lowing. l2 P I I I I SMSLLEST l%TTERN I UNIT OF SYMSIETRY I I I I I I I 0? I I I I 8 INJECTION WELL o PRODUCTION WELL I DEVELOPED FIVE-SPOT WELL PATTE RN FIGURE I the study. APer the pressure distx'ibution for a...
On the development of nugget growth model for resistance spot welding
Zhou, Kang, E-mail: zhoukang326@126.com, E-mail: melcai@ust.hk; Cai, Lilong, E-mail: zhoukang326@126.com, E-mail: melcai@ust.hk [Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)
2014-04-28T23:59:59.000Z
In this paper, we developed a general mathematical model to estimate the nugget growth process based on the heat energy delivered into the welds by the resistance spot welding. According to the principles of thermodynamics and heat transfer, and the effect of electrode force during the welding process, the shape of the nugget can be estimated. Then, a mathematical model between heat energy absorbed and nugget diameter can be obtained theoretically. It is shown in this paper that the nugget diameter can be precisely described by piecewise fractal polynomial functions. Experiments were conducted with different welding operation conditions, such as welding currents, workpiece thickness, and widths, to validate the model and the theoretical analysis. All the experiments confirmed that the proposed model can predict the nugget diameters with high accuracy based on the input heat energy to the welds.
Functional identification of the non-specific nuclease from white spot syndrome virus
Li Li [Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, SOA, 178 Daxue Road, Xiamen 361005 (China); Lin Shumei [School of life science, Xiamen University, Xiamen 361005 (China); Yanga Feng [Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, SOA, 178 Daxue Road, Xiamen 361005 (China)]. E-mail: mbiotech@public.xm.fj.cn
2005-07-05T23:59:59.000Z
The product encoded by the wsv191 gene from shrimp white spot syndrome virus (WSSV) is homologous with non-specific nucleases (NSN) of other organisms. To functionally identify the protein, the wsv191 gene was expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein with 6His-tag at C-terminal. The fusion protein (termed as rWSSV-NSN) was purified using Ni-NTA affinity chromatography under denatured conditions, renatured and characterized by three methods. The results showed that rWSSV-NSN could hydrolyze both DNA and RNA. 5'-RACE result revealed that the transcription initiation site of the wsv191 gene was located at nucleotide residue G of the predicted ATG triplet. Therefore, we concluded that the next ATG should be the genuine translation initiation codon of the wsv191 gene. Western blot analysis revealed that the molecular mass of natural WSSV-NSN was 37 kDa.
Empirical analysis of the spot market implications ofprice-elastic demand
Siddiqui, Afzal S.; Bartholomew, Emily S.; Marnay, Chris
2004-07-08T23:59:59.000Z
Regardless of the form of restructuring, deregulated electricity industries share one common feature: the absence of any significant, rapid demand-side response to the wholesale (or, spotmarket) price. For a variety of reasons, electricity industries continue to charge most consumers an average cost based on regulated retail tariff from the era of vertical integration, even as the retailers themselves are forced to purchase electricity at volatile wholesale prices set in open markets. This results in considerable price risk for retailers, who are sometimes forbidden by regulators from signing hedging contracts. More importantly, because end-users do not perceive real-time (or even hourly or daily) fluctuations in the wholesale price of electricity, they have no incentive to adjust their consumption in response to price signals. Consequently, demand for electricity is highly inelastic, and electricity generation resources can be stretched to the point where system stability is threatened. This, then, facilitates many other problems associated with electricity markets, such as market power and price volatility. Indeed, economic theory suggests that even modestly price-responsive demand can remove the stress on generation resources and decrease spot prices. To test this theory, we use actual generator bid data from the New York control area to construct supply stacks, and intersect them with demand curves of various slopes to approximate different levels of demand elasticity. We then estimate the potential impact of real-time pricing on the equilibrium spot price and quantity. These results indicate the immediate benefits that could be derived from a more price-elastic demand. Such analysis can provide policymakers with a measure of how effective price-elastic demand can potentially reduce prices and maintain consumption within the capability of generation resources.
Empirical Analysis of the Spot Market Implications ofPrice-Responsive Demand
Siddiqui, Afzal S.; Bartholomew, Emily S.; Marnay, Chris
2005-08-01T23:59:59.000Z
Regardless of the form of restructuring, deregulatedelectricity industries share one common feature: the absence of anysignificant, rapid demand-side response to the wholesale (or, spotmarket) price. For a variety of reasons, most electricity consumers stillpay an average cost based regulated retail tariff held over from the eraof vertical integration, even as the retailers themselves are oftenforced to purchase electricity at volatile wholesale prices set in openmarkets. This results in considerable price risk for retailers, who aresometimes additionally forbidden by regulators from signing hedgingcontracts. More importantly, because end-users do not perceive real-time(or even hourly or daily) fluctuations in the wholesale price ofelectricity, they have no incentive to adjust their consumptionaccordingly. Consequently, demand for electricity is highly inelastic,which together with the non storability of electricity that requiresmarket clearing over very short time steps spawn many other problemsassociated with electricity markets, such as exercise of market power andprice volatility. Indeed, electricity generation resources can bestretched to the point where system adequacy is threatened. Economictheory suggests that even modest price responsiveness can relieve thestress on generation resources and decrease spot prices. To quantify thiseffect, actual generator bid data from the New York control area is usedto construct supply stacks and intersect them with demand curves ofvarious slopes to approximate the effect of different levels of demandresponse. The potential impact of real-time pricing (RTP) on theequilibrium spot price and quantity is then estimated. These resultsindicate the immediate benefits that could be derived from a moreprice-responsive demand providing policymakers with a measure of howprices can be potentially reduced and consumption maintained within thecapability of generation assets.
Pappu, Hanu R.
Plant Disease Note 2004 | Iris Yellow Spot Virus in Onion Bulb and Seed Crops in Washington Yellow Spot Virus in Onion Bulb and Seed Crops in Washington. L. J. du Toit, Washington State University of the NP gene. In August 2003, symptoms of IYSV infection were observed in two onion bulb crops, each
Maini, Philip K.
Spots and stripes: Pleomorphic patterning of stem cells via p-ERK-dependent cell chemotaxis shown cells Placode ERK Mathematical modeling Chemotaxis A key issue in stem cell biology patterns, ranging from stripes to spots, can be obtained when the level of p-ERK activity is adjusted
Laughlin, Robert B.
Chapter V Docket No. PA02-2-000 Price Manipulation in Western MarketsV-1 V. The Influence of Electricity Spot Prices on Electricity Forward Prices Summary of Results The vital link between the spot price and forward price for a commodity is the ability to store the commodity. In essence, someone can meet future
Coupled Deterministic-Monte Carlo Transport for Radiation Portal Modeling
Smith, Leon E.; Miller, Erin A.; Wittman, Richard S.; Shaver, Mark W.
2008-01-14T23:59:59.000Z
Radiation portal monitors are being deployed, both domestically and internationally, to detect illicit movement of radiological materials concealed in cargo. Evaluation of the current and next generations of these radiation portal monitor (RPM) technologies is an ongoing process. 'Injection studies' that superimpose, computationally, the signature from threat materials onto empirical vehicle profiles collected at ports of entry, are often a component of the RPM evaluation process. However, measurement of realistic threat devices can be both expensive and time-consuming. Radiation transport methods that can predict the response of radiation detection sensors with high fidelity, and do so rapidly enough to allow the modeling of many different threat-source configurations, are a cornerstone of reliable evaluation results. Monte Carlo methods have been the primary tool of the detection community for these kinds of calculations, in no small part because they are particularly effective for calculating pulse-height spectra in gamma-ray spectrometers. However, computational times for problems with a high degree of scattering and absorption can be extremely long. Deterministic codes that discretize the transport in space, angle, and energy offer potential advantages in computational efficiency for these same kinds of problems, but the pulse-height calculations needed to predict gamma-ray spectrometer response are not readily accessible. These complementary strengths for radiation detection scenarios suggest that coupling Monte Carlo and deterministic methods could be beneficial in terms of computational efficiency. Pacific Northwest National Laboratory and its collaborators are developing a RAdiation Detection Scenario Analysis Toolbox (RADSAT) founded on this coupling approach. The deterministic core of RADSAT is Attila, a three-dimensional, tetrahedral-mesh code originally developed by Los Alamos National Laboratory, and since expanded and refined by Transpire, Inc. [1]. MCNP5 is used to calculate sensor pulse-height tallies. RADSAT methods, including adaptive, problem-specific energy-group creation, ray-effect mitigation strategies and the porting of deterministic angular flux to MCNP for individual particle creation are described in [2][3][4]. This paper discusses the application of RADSAT to the modeling of gamma-ray spectrometers in RPMs.
Perfetti, Christopher M [ORNL; Rearden, Bradley T [ORNL
2014-01-01T23:59:59.000Z
This work introduces a new approach for calculating sensitivity coefficients for generalized neutronic responses to nuclear data uncertainties using continuous-energy Monte Carlo methods. The approach presented in this paper, known as the GEAR-MC method, allows for the calculation of generalized sensitivity coefficients for multiple responses in a single Monte Carlo calculation with no nuclear data perturbations or knowledge of nuclear covariance data. The theory behind the GEAR-MC method is presented here, and proof of principle is demonstrated by using the GEAR-MC method to calculate sensitivity coefficients for responses in several 3D, continuous-energy Monte Carlo applications.
Franke, B. C. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Prinja, A. K. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131 (United States)
2013-07-01T23:59:59.000Z
The stochastic Galerkin method (SGM) is an intrusive technique for propagating data uncertainty in physical models. The method reduces the random model to a system of coupled deterministic equations for the moments of stochastic spectral expansions of result quantities. We investigate solving these equations using the Monte Carlo technique. We compare the efficiency with brute-force Monte Carlo evaluation of uncertainty, the non-intrusive stochastic collocation method (SCM), and an intrusive Monte Carlo implementation of the stochastic collocation method. We also describe the stability limitations of our SGM implementation. (authors)
A study of the contrast of a submerged disc using Monte Carlo techniques
Hagan, Donald Frank
1980-01-01T23:59:59.000Z
in the simulation of lioht interactions within the Earth's ocean system. Using the Monte Carlo computer program the contrast of a Secchi disc and its ocean background was calculated. A Secchi disc 1s a horizontal disc in the ocean that is v1ewed from the surface... of samples which requires more computation time. Before the advent of high speed computers, the Monte Carlo Method was generally useless because of the massive amount of computation it required. The Monte Carlo Method is fairly simple in application...
Enhanced physics design with hexagonal repeated structure tools using Monte Carlo methods
Carter, L L; Lan, J S; Schwarz, R A
1991-01-01T23:59:59.000Z
This report discusses proposed new missions for the Fast Flux Test Facility (FFTF) reactor which involve the use of target assemblies containing local hydrogenous moderation within this otherwise fast reactor. Parametric physics design studies with Monte Carlo methods are routinely utilized to analyze the rapidly changing neutron spectrum. An extensive utilization of the hexagonal lattice within lattice capabilities of the Monte Carlo Neutron Photon (MCNP) continuous energy Monte Carlo computer code is applied here to solving such problems. Simpler examples that use the lattice capability to describe fuel pins within a brute force'' description of the hexagonal assemblies are also given.
Chapman, Michael S.
www.octri.org/funding "Designing a Convenient and Precise Device for Home Dried Blood Spot-art methods require frequent laboratory visits for venous blood draws and subsequent analysis. There are no readily available methods for in-home collection of patient blood samples with the necessary accuracy
Umstadter, Donald
Repetitive petawatt-class laser with near-diffraction-limited focal spot and transform-loop feedback control systems in the temporal and spatial domains are used to yield Fourier-transform acceleration and x-ray generation. Keywords: petawatt, diffraction limited, transform limited, spatial
Harilal, S. S.
Ultrafast laser ablation ICP-MS: role of spot size, laser fluence, and repetition rate in signal,a Richard E. Russob and Ahmed Hassaneina Ultrafast laser ablation inductively coupled plasma mass system. Though ultrafast laser ablation sample introduction provides better accuracy and precision
Assessing the Degree of Spot Market Integration For U.S. Natural Gas: Evidence from Daily Price Data
to decouple the production and trading of the commodity natural gas from its transportation. Advocates arguedAssessing the Degree of Spot Market Integration For U.S. Natural Gas: Evidence from Daily Price Economics Abstract: This paper assesses the degree of market integration in the U.S. natural gas market
Strategic Behavior in Spot Markets for Electricity when Load is Stochastic T.D. Mount Department that the average price in 1999, when market-based offers were allowed, was twice as high as it was in the previous two seasons when offers had to be cost-based. The primary cause was that the price spikes in 1999 were
P~!ETRIC STUDY OF HEAT FLOW DURING RESISTANCE SPOT WELDING Euiwhan Kim and Thomas W. Eagar
Eagar, Thomas W.
i ...) P~!ETRIC STUDY OF HEAT FLOW DURING RESISTANCE SPOT WELDING Euiwhan Kim and Thomas W. Eagar case of resistance welding to see the effects of each parameter on the lobe shape. The parameters include material proper- ties, geometry of electrodes and work piece, weld time and current
Kuzmanovic, Aleksandar
Identifying HotSpots in Lung Cancer Data Using Association Rule Mining Ankit Agrawal and Alok, IL 60201, USA Email: {ankitag,choudhar}@eecs.northwestern.edu Abstract--We analyze the lung cancer. The resulting rules conform with existing biomedical knowledge and provide interesting insights into lung cancer
An Analysis of Price Volatility in Different Spot Markets for Electricity in the U.S.A.
An Analysis of Price Volatility in Different Spot Markets for Electricity in the U.S.A. by Tim for electricity in the USA vary in fundamental ways. In particular, markets in the East, such as New England, New in the new auction markets for electricity can be described by a stochastic regime-switching model
INVESTIGATION OF "HOT-SPOTS" AS A FUNCTION OF MATERIAL REMOVAL IN A LARGE-GRAIN NIOBIUM CAVITY
Gianluigi Ciovati; Peter Kneisel
2006-08-21T23:59:59.000Z
Poster - The performance of a single-cell cavity made of RRR > 200 large-grain niobium has been investigated as a function of material removal by buffered chemical polishing. Temperature maps of the cavity surface at 1.7 and 2.0 K were taken for each step of chemical etching and revealed several 'hot-spots', which contribute to the degradation of the cavity quality factor as a function of the RF surface field, mostly at high field levels. It was found that the number of 'hot-spots' decreased for larger material removal. Interestingly, the losses of the 'hot-spots' at different locations evolved differently for successive material removal. The cavity achieved peak surface magnetic fields of about of 130 mT and was limited mostly by thermal quench. By measuring the temperature dependence of the surface resistance at low field between 4.2 K and 1.7 K, the variation of niobium material parameters as a function of material removal could also be investigated. This contribution shows the results of the RF tests along with the temperature maps and the analysis of the losses caused by the 'hot-spots'.
treatment of the ge- ometry, but successive versions added such features as cross-section libraries and green above. As the temperature of the plasma decreases, lattice-like peaks begin to form in the pair
Monte Carlo sampling from the quantum state space. I
Jiangwei Shang; Yi-Lin Seah; Hui Khoon Ng; David John Nott; Berthold-Georg Englert
2015-04-27T23:59:59.000Z
High-quality random samples of quantum states are needed for a variety of tasks in quantum information and quantum computation. Searching the high-dimensional quantum state space for a global maximum of an objective function with many local maxima or evaluating an integral over a region in the quantum state space are but two exemplary applications of many. These tasks can only be performed reliably and efficiently with Monte Carlo methods, which involve good samplings of the parameter space in accordance with the relevant target distribution. We show how the standard strategies of rejection sampling, importance sampling, and Markov-chain sampling can be adapted to this context, where the samples must obey the constraints imposed by the positivity of the statistical operator. For a comparison of these sampling methods, we generate sample points in the probability space for two-qubit states probed with a tomographically incomplete measurement, and then use the sample for the calculation of the size and credibility of the recently-introduced optimal error regions [see New J. Phys. 15 (2013) 123026]. Another illustration is the computation of the fractional volume of separable two-qubit states.
Monte Carlo simulation of the terrestrial hydrogen exosphere
Hodges, R.R. Jr. [Univ. of Texas, Dallas, TX (United States)
1994-12-01T23:59:59.000Z
Methods for Monte Carlo simulation of planetary exospheres have evolved from early work on the lunar atmosphere, where the regolith surface provides a well defined exobase. A major limitation of the successor simulations of the exospheres of Earth and Venus is the use of an exobase surface as an artifice to separate the collisional processes of the thermosphere from a collisionles exosphere. In this paper a new generalized approach to exosphere simulation is described, wherein the exobase is replaced by a barometric depletion of the major constitents of the thermosphere. Exospheric atoms in the thermosphere-exosphere transition region, and in the outer exosphere as well, travel in ballistic trajectories that are interrupted by collisons with the background gas, and by charge exchange interactions with ionospheric particles. The modified simulator has been applied to the terrestrial hydrogen exosphere problem, using velocity dependent differential cross sections to provide statistically correct collisional scattering in H-O and H-H(+) interactions. Global models are presented for both solstice and equinox over the effective solar cycle range of the F{sub 10.7} index (80 to 230). Simulation results show significant differences with previous terrestrial exosphere models, as well as with the H distributions of the MSIS-86 thermosphere model.
Monte Carlo Simulations of Cosmic Rays Hadronic Interactions
Aguayo Navarrete, Estanislao; Orrell, John L.; Kouzes, Richard T.
2011-04-01T23:59:59.000Z
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%.
Monte Carlo Sampling of Negative-temperature Plasma States
John A. Krommes; Sharadini Rath
2002-07-19T23:59:59.000Z
A Monte Carlo procedure is used to generate N-particle configurations compatible with two-temperature canonical equilibria in two dimensions, with particular attention to nonlinear plasma gyrokinetics. An unusual feature of the problem is the importance of a nontrivial probability density function R0(PHI), the probability of realizing a set {Phi} of Fourier amplitudes associated with an ensemble of uniformly distributed, independent particles. This quantity arises because the equilibrium distribution is specified in terms of {Phi}, whereas the sampling procedure naturally produces particles states gamma; {Phi} and gamma are related via a gyrokinetic Poisson equation, highly nonlinear in its dependence on gamma. Expansion and asymptotic methods are used to calculate R0(PHI) analytically; excellent agreement is found between the large-N asymptotic result and a direct numerical calculation. The algorithm is tested by successfully generating a variety of states of both positive and negative temperature, including ones in which either the longest- or shortest-wavelength modes are excited to relatively very large amplitudes.
Monte Carlo simulations of lattice models for single polymer systems
Hsu, Hsiao-Ping, E-mail: hsu@mpip-mainz.mpg.de [Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz (Germany)
2014-10-28T23:59:59.000Z
Single linear polymer chains in dilute solutions under good solvent conditions are studied by Monte Carlo simulations with the pruned-enriched Rosenbluth method up to the chain length N?O(10{sup 4}). Based on the standard simple cubic lattice model (SCLM) with fixed bond length and the bond fluctuation model (BFM) with bond lengths in a range between 2 and ?(10), we investigate the conformations of polymer chains described by self-avoiding walks on the simple cubic lattice, and by random walks and non-reversible random walks in the absence of excluded volume interactions. In addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential. The persistence lengths of chains extracted from the orientational correlations are estimated for all cases. We show that chains based on the BFM are more flexible than those based on the SCLM for a fixed bending energy. The microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified. Our simulations clarify that a different mapping ratio between the coarse-grained models and the atomistically realistic description of polymers is required in a coarse-graining approach due to the different crossovers to the asymptotic behavior.
A review of Monte Carlo simulations of polymers with PERM
Hsiao-Ping Hsu; Peter Grassberger
2011-07-06T23:59:59.000Z
In this review, we describe applications of the pruned-enriched Rosenbluth method (PERM), a sequential Monte Carlo algorithm with resampling, to various problems in polymer physics. PERM produces samples according to any given prescribed weight distribution, by growing configurations step by step with controlled bias, and correcting "bad" configurations by "population control". The latter is implemented, in contrast to other population based algorithms like e.g. genetic algorithms, by depth-first recursion which avoids storing all members of the population at the same time in computer memory. The problems we discuss all concern single polymers (with one exception), but under various conditions: Homopolymers in good solvents and at the $\\Theta$ point, semi-stiff polymers, polymers in confining geometries, stretched polymers undergoing a forced globule-linear transition, star polymers, bottle brushes, lattice animals as a model for randomly branched polymers, DNA melting, and finally -- as the only system at low temperatures, lattice heteropolymers as simple models for protein folding. PERM is for some of these problems the method of choice, but it can also fail. We discuss how to recognize when a result is reliable, and we discuss also some types of bias that can be crucial in guiding the growth into the right directions.
Nuclear Force from Monte Carlo Simulations of Lattice Quantum Chromodynamics
S. Aoki; T. Hatsuda; N. Ishii
2008-10-24T23:59:59.000Z
The nuclear force acting between protons and neutrons is studied in the Monte Carlo simulations of the fundamental theory of the strong interaction, the quantum chromodynamics defined on the hypercubic space-time lattice. After a brief summary of the empirical nucleon-nucleon (NN) potentials which can fit the NN scattering experiments in high precision, we outline the basic formulation to derive the potential between the extended objects such as the nucleons composed of quarks. The equal-time Bethe-Salpeter amplitude is a key ingredient for defining the NN potential on the lattice. We show the results of the numerical simulations on a $32^4$ lattice with the lattice spacing $a \\simeq 0.137 $fm (lattice volume (4.4 fm)$^4$) in the quenched approximation. The calculation was carried out using the massively parallel computer Blue Gene/L at KEK. We found that the calculated NN potential at low energy has basic features expected from the empirical NN potentials; attraction at long and medium distances and the repulsive core at short distance. Various future directions along this line of research are also summarized.
Protein folding and phylogenetic tree reconstruction using stochastic approximation Monte Carlo
Cheon, Sooyoung
2007-09-17T23:59:59.000Z
folding problems. The numerical results indicate that it outperforms simulated annealing and conventional Monte Carlo algorithms as a stochastic optimization algorithm. We also propose one method for the use of secondary structures in protein folding...
Xu, Sheng, S.M. Massachusetts Institute of Technology
2013-01-01T23:59:59.000Z
In order to use Monte Carlo methods for reactor simulations beyond benchmark activities, the traditional way of preparing and using nuclear cross sections needs to be changed, since large datasets of cross sections at many ...
Monte Carlo and thermal hydraulic coupling using low-order nonlinear diffusion acceleration
Herman, Bryan R. (Bryan Robert)
2014-01-01T23:59:59.000Z
Monte Carlo (MC) methods for reactor analysis are most often employed as a benchmark tool for other transport and diffusion methods. In this work, we identify and resolve a few of the issues associated with using MC as a ...
Paris-Sud XI, Université de
Emission Computed Tomography (SPECT) images is degraded by physical effects, namely photon attenuation datasets are currently under investigation. Keywords : single photon emission computed tomography; Monte Emission Computed Tomography (SPECT), the qualitative and quantitative accuracy of images is degraded
APR1400 LBLOCA uncertainty quantification by Monte Carlo method and comparison with Wilks' formula
Hwang, M.; Bae, S.; Chung, B. D. [Korea Atomic Energy Research Inst., 150 Dukjin-dong, Yuseong-gu, Daejeon (Korea, Republic of)
2012-07-01T23:59:59.000Z
An analysis of the uncertainty quantification for the PWR LBLOCA by the Monte Carlo calculation has been performed and compared with the tolerance level determined by Wilks' formula. The uncertainty range and distribution of each input parameter associated with the LBLOCA accident were determined by the PIRT results from the BEMUSE project. The Monte-Carlo method shows that the 95. percentile PCT value can be obtained reliably with a 95% confidence level using the Wilks' formula. The extra margin by the Wilks' formula over the true 95. percentile PCT by the Monte-Carlo method was rather large. Even using the 3 rd order formula, the calculated value using the Wilks' formula is nearly 100 K over the true value. It is shown that, with the ever increasing computational capability, the Monte-Carlo method is accessible for the nuclear power plant safety analysis within a realistic time frame. (authors)
Show me the way to Monte Carlo: density-based trajectory Steven Strachan1
Murray-Smith, Roderick
with a combination of Global Positioning System data, a music player, inertial sen- sing, magnetic bearing data, magnetic bearing data and Monte Carlo samp- ling and modulates a listener's music in order to guide them
Improvements and applications of the Uniform Fission Site method in Monte Carlo
Hunter, Jessica Lynn
2014-01-01T23:59:59.000Z
Monte Carlo methods for reactor analysis have been in development with the eventual goal of full-core analysis. To attain results with reasonable uncertainties, large computational resources are needed. Variance reduction ...
Direct Monte Carlo simulation of chemical reaction systems: Dissociation and recombination
Anderson, James B.
Direct Monte Carlo simulation of chemical reaction systems: Dissociation and recombination Shannon Carlo simulations of a chemical reaction system with bimolecular and termolecular dissociation8 to be well suited for treating chemical reaction systems with nonequilibrium distributions, coupled gas
Physics-based Predictive Time Propagation Method for Monte Carlo Coupled Depletion Simulations
Johns, Jesse Merlin
2014-12-18T23:59:59.000Z
Monte Carlo techniques for numerical simulation has humble beginnings during the Manhattan project. They were developed to rein in intractable problems of nuclear implosion hydrodynamics, thermonuclear reactions, and computing neutron fluxes and core...
Combining Strategies for Parallel Stochastic Approximation Monte Carlo Algorithm of Big Data
Lin, Fang-Yu
2014-10-15T23:59:59.000Z
of iterations and is prone to get trapped into local optima. On the other hand, Stochastic Approximation in Monte Carlo algorithm (SAMC), a very sophisticated algorithm in theory and applications, can avoid getting trapped into local optima and produce more...
Walsh, Jonathan A. (Jonathan Alan)
2014-01-01T23:59:59.000Z
This thesis presents the development and analysis of computational methods for efficiently accessing and utilizing nuclear data in Monte Carlo neutron transport code simulations. Using the OpenMC code, profiling studies ...
Duo at Santa Fe's Monte del Sol Charter School takes top award...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
New Mexico Supercomputing Challenge Duo at Santa Fe's Monte del Sol Charter School takes top award in 25th New Mexico Supercomputing Challenge Meghan Hill and Katelynn James took...
Pasciak, Alexander Samuel
2007-04-25T23:59:59.000Z
Advancements in parallel and cluster computing have made many complex Monte Carlo simulations possible in the past several years. Unfortunately, cluster computers are large, expensive, and still not fast enough to make the ...
Physics-based Predictive Time Propagation Method for Monte Carlo Coupled Depletion Simulations
Johns, Jesse Merlin
2014-12-18T23:59:59.000Z
Monte Carlo techniques for numerical simulation has humble beginnings during the Manhattan project. They were developed to rein in intractable problems of nuclear implosion hydrodynamics, thermonuclear reactions, and computing neutron fluxes and core...
MARKOV CHAIN MONTE CARLO FOR AUTOMATED TRACKING OF GENEALOGY IN MICROSCOPY VIDEOS
MARKOV CHAIN MONTE CARLO FOR AUTOMATED TRACKING OF GENEALOGY IN MICROSCOPY VIDEOS KATHLEEN CHAMPION of the nuclei in the images and their genealogies. Evan Tice '09 has already developed some code that aims
Parallel Markov Chain Monte Carlo Methods for Large Scale Statistical Inverse Problems
Wang, Kainan
2014-04-18T23:59:59.000Z
but also the uncertainty of these estimations. Markov chain Monte Carlo (MCMC) is a useful technique to sample the posterior distribution and information can be extracted from the sampled ensemble. However, MCMC is very expensive to compute, especially...
Exponentially-convergent Monte Carlo for the One-dimensional Transport Equation
Peterson, Jacob Ross
2014-04-23T23:59:59.000Z
singular problems. Computational results are presented demonstrating the efficacy of the new approach. We tested our ECMC algorithm against standard Monte Carlo and found the ECMC method to be generally much more efficient. For a manufacture solution...
Fourth-order diffusion Monte Carlo algorithms for solving quantum many-body problems
Forbert, HA; Chin, Siu A.
2001-01-01T23:59:59.000Z
By decomposing the important sampled imaginary time Schrodinger evolution operator to fourth order with positive coefficients, we derived a number of distinct fourth-order diffusion Monte Carlo algorithms. These sophisticated algorithms require...
Radiative transfer in the earth's atmosphere-ocean system using Monte Carlo techniques
Bradley, Paul Andrew
1987-01-01T23:59:59.000Z
TRANSFER PROBLEM MONTE CARLO METHOD Assumptions of the Model Photon Pathlength Emulation Techniques Sampling Scattering Functions: Angles and Probabilities Emulation of an Interface Computing the Radiance by Statistical Estimation Determination... radiance values in both the atmosphere and the ocean from the scattering functions and other input data, with a Monte Carlo computer code. The polarization ot the radiation was taken into account by Kattawar et al. s in their computation...
PyMercury: Interactive Python for the Mercury Monte Carlo Particle Transport Code
Iandola, F N; O'Brien, M J; Procassini, R J
2010-11-29T23:59:59.000Z
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.
MONTE CARLO SIMULATION OF METASTABLE OXYGEN PHOTOCHEMISTRY IN COMETARY ATMOSPHERES
Bisikalo, D. V.; Shematovich, V. I. [Institute of Astronomy of the Russian Academy of Sciences, Moscow (Russian Federation); Gérard, J.-C.; Hubert, B. [Laboratory for Planetary and Atmospheric Physics (LPAP), University of Liège, Liège (Belgium); Jehin, E.; Decock, A. [Origines Cosmologiques et Astrophysiques (ORCA), University of Liège (Belgium); Hutsemékers, D. [Extragalactic Astrophysics and Space Observations (EASO), University of Liège (Belgium); Manfroid, J., E-mail: B.Hubert@ulg.ac.be [High Energy Astrophysics Group (GAPHE), University of Liège (Belgium)
2015-01-01T23:59:59.000Z
Cometary atmospheres are produced by the outgassing of material, mainly H{sub 2}O, CO, and CO{sub 2} from the nucleus of the comet under the energy input from the Sun. Subsequent photochemical processes lead to the production of other species generally absent from the nucleus, such as OH. Although all comets are different, they all have a highly rarefied atmosphere, which is an ideal environment for nonthermal photochemical processes to take place and influence the detailed state of the atmosphere. We develop a Monte Carlo model of the coma photochemistry. We compute the energy distribution functions (EDF) of the metastable O({sup 1}D) and O({sup 1}S) species and obtain the red (630 nm) and green (557.7 nm) spectral line shapes of the full coma, consistent with the computed EDFs and the expansion velocity. We show that both species have a severely non-Maxwellian EDF, that results in broad spectral lines and the suprathermal broadening dominates due to the expansion motion. We apply our model to the atmosphere of comet C/1996 B2 (Hyakutake) and 103P/Hartley 2. The computed width of the green line, expressed in terms of speed, is lower than that of the red line. This result is comparable to previous theoretical analyses, but in disagreement with observations. We explain that the spectral line shape does not only depend on the exothermicity of the photochemical production mechanisms, but also on thermalization, due to elastic collisions, reducing the width of the emission line coming from the O({sup 1}D) level, which has a longer lifetime.
Utility of Monte Carlo Modelling for Holdup Measurements.
Belian, Anthony P.; Russo, P. A. (Phyllis A.); Weier, Dennis R. (Dennis Ray),
2005-01-01T23:59:59.000Z
Non-destructive assay (NDA) measurements performed to locate and quantify holdup in the Oak Ridge K25 enrichment cascade used neutron totals counting and low-resolution gamma-ray spectroscopy. This facility housed the gaseous diffusion process for enrichment of uranium, in the form of UF{sub 6} gas, from {approx} 20% to 93%. Inventory of {sup 235}U inventory in K-25 is all holdup. These buildings have been slated for decontaminatino and decommissioning. The NDA measurements establish the inventory quantities and will be used to assure criticality safety and meet criteria for waste analysis and transportation. The tendency to err on the side of conservatism for the sake of criticality safety in specifying total NDA uncertainty argues, in the interests of safety and costs, for obtaining the best possible value of uncertainty at the conservative confidence level for each item of process equipment. Variable deposit distribution is a complex systematic effect (i.e., determined by multiple independent variables) on the portable NDA results for very large and bulk converters that contributes greatly to total uncertainty for holdup in converters measured by gamma or neutron NDA methods. Because the magnitudes of complex systematic effects are difficult to estimate, computational tools are important for evaluating those that are large. Motivated by very large discrepancies between gamma and neutron measurements of high-mass converters with gamma results tending to dominate, the Monte Carlo code MCNP has been used to determine the systematic effects of deposit distribution on gamma and neutron results for {sup 235}U holdup mass in converters. This paper details the numerical methodology used to evaluate large systematic effects unique to each measurement type, validates the methodology by comparison with measurements, and discusses how modeling tools can supplement the calibration of instruments used for holdup measurements by providing realistic values at well-defined confidence levels for dominating systematic effects.
Review of Monte Carlo simulations for backgrounds from radioactivity
Selvi, Marco [INFN - Sezione di Bologna (Italy)] [INFN - Sezione di Bologna (Italy)
2013-08-08T23:59:59.000Z
For all experiments dealing with the rare event searches (neutrino, dark matter, neutrino-less double-beta decay), the reduction of the radioactive background is one of the most important and difficult tasks. There are basically two types of background, electron recoils and nuclear recoils. The electron recoil background is mostly from the gamma rays through the radioactive decay. The nuclear recoil background is from neutrons from spontaneous fission, (?, n) reactions and muoninduced interactions (spallations, photo-nuclear and hadronic interaction). The external gammas and neutrons from the muons and laboratory environment, can be reduced by operating the detector at deep underground laboratories and by placing active or passive shield materials around the detector. The radioactivity of the detector materials also contributes to the background; in order to reduce it a careful screening campaign is mandatory to select highly radio-pure materials. In this review I present the status of current Monte Carlo simulations aimed to estimate and reproduce the background induced by gamma and neutron radioactivity of the materials and the shield of rare event search experiment. For the electromagnetic background a good level of agreement between the data and the MC simulation has been reached by the XENON100 and EDELWEISS experiments, using the GEANT4 toolkit. For the neutron background, a comparison between the yield of neutrons from spontaneous fission and (?, n) obtained with two dedicated softwares, SOURCES-4A and the one developed by Mei-Zhang-Hime, show a good overall agreement, with total yields within a factor 2 difference. The energy spectra from SOURCES-4A are in general smoother, while those from MZH presents sharp peaks. The neutron propagation through various materials has been studied with two MC codes, GEANT4 and MCNPX, showing a reasonably good agreement, inside 50% discrepancy.
New Hampshire, University of
Septoria, are two destructive tomato diseases which occur each year in the northeastern United States. Both. Septoria overwinters in crop debris. Tomato Leaf Spots Family, Home & Garden Education Center practical of lines in tan centers. Fruit spots on stem end, ½ inch No fruit spots. in diameter, dark, leathery
Direct Simulations of Homogeneous Bubble Nucleation: Agreement with CNT and no Local Hot Spots
Jürg Diemand; Raymond Angélil; Kyoko K. Tanaka; Hidekazu Tanaka
2014-10-24T23:59:59.000Z
We present results from direct, large-scale molecular dynamics (MD) simulations of homogeneous bubble (liquid-to-vapor) nucleation. The simulations contain half a billion Lennard-Jones (LJ) atoms and cover up to 56 million time-steps. The unprecedented size of the simulated volumes allows us to resolve the nucleation and growth of many bubbles per run in simple direct micro-canonical (NVE) simulations while the ambient pressure and temperature remain almost perfectly constant. We find bubble nucleation rates which are lower than in most of the previous, smaller simulations. It is widely believed that classical nucleation theory (CNT) generally underestimates bubble nucleation rates by very large factors. However, our measured rates are within two orders of magnitude of CNT predictions - only at very low temperatures does CNT underestimate the nucleation rate significantly. Introducing a small, positive Tolman length leads to very good agreement at all temperatures, as found in our recent vapor-to-liquid nucleation simulations. The critical bubbles sizes derived with the nucleation theorem agree well with the CNT predictions at all temperatures. Local hot spots reported in the literature are not seen: Regions where a bubble nucleation events will occur are not above the average temperature, and no correlation of temperature fluctuations with subsequent bubble formation is seen.
Statistical Analysis of Microarray Data with Replicated Spots: A Case Study withSynechococcusWH8102
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Thomas, E. V.; Phillippy, K. H.; Brahamsha, B.; Haaland, D. M.; Timlin, J. A.; Elbourne, L. D. H.; Palenik, B.; Paulsen, I. T.
2009-01-01T23:59:59.000Z
Until recently microarray experiments often involved relatively few arrays with only a single representation of each gene on each array. A complete genome microarray with multiple spots per gene (spread out spatially across the array) was developed in order to compare the gene expression of a marine cyanobacterium and a knockout mutant strain in a defined artificial seawater medium. Statistical methods were developed for analysis in the special situation of this case study where there is gene replication within an array and where relatively few arrays are used, which can be the case with current array technology. Due in partmore »to the replication within an array, it was possible to detect very small changes in the levels of expression between the wild type and mutant strains. One interesting biological outcome of this experiment is the indication of the extent to which the phosphorus regulatory system of this cyanobacterium affects the expression of multiple genes beyond those strictly involved in phosphorus acquisition.« less
Final Report: 06-LW-013, Nuclear Physics the Monte Carlo Way
Ormand, W E
2009-03-01T23:59:59.000Z
This is document reports the progress and accomplishments achieved in 2006-2007 with LDRD funding under the proposal 06-LW-013, 'Nuclear Physics the Monte Carlo Way'. The project was a theoretical study to explore a novel approach to dealing with a persistent problem in Monte Carlo approaches to quantum many-body systems. The goal was to implement a solution to the notorious 'sign-problem', which if successful, would permit, for the first time, exact solutions to quantum many-body systems that cannot be addressed with other methods. In this document, we outline the progress and accomplishments achieved during FY2006-2007 with LDRD funding in the proposal 06-LW-013, 'Nuclear Physics the Monte Carlo Way'. This project was funded under the Lab Wide LDRD competition at Lawrence Livermore National Laboratory. The primary objective of this project was to test the feasibility of implementing a novel approach to solving the generic quantum many-body problem, which is one of the most important problems being addressed in theoretical physics today. Instead of traditional methods based matrix diagonalization, this proposal focused a Monte Carlo method. The principal difficulty with Monte Carlo methods, is the so-called 'sign problem'. The sign problem, which will discussed in some detail later, is endemic to Monte Carlo approaches to the quantum many-body problem, and is the principal reason that they have not been completely successful in the past. Here, we outline our research in the 'shifted-contour method' applied the Auxiliary Field Monte Carlo (AFMC) method.
Hutto Fretty, Corneil Kimberly
2014-05-06T23:59:59.000Z
of translucency of the enamel, as a result of demineralization. No cavitation is usually evident, but the surface may feel rougher than normal when checked with a sharp instrument. Sliverstone described four distinct zones of a carious lesion in enamel... followed by shorter periods of remineralization, will result in cavitation of the enamel surface.2 Etiology of White Spot Lesions WSLs are caused by the accumulation of plaque and bacteria on the enamel surfaces of teeth, and are affected...
A Fano cavity test for Monte Carlo proton transport algorithms
Sterpin, Edmond, E-mail: esterpin@yahoo.fr [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels (Belgium)] [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels (Belgium); Sorriaux, Jefferson; Souris, Kevin [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Université catholique de Louvain, ICTEAM institute, Chemin du cyclotron 6, 1348 Louvain-la-Neuve (Belgium)] [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Université catholique de Louvain, ICTEAM institute, Chemin du cyclotron 6, 1348 Louvain-la-Neuve (Belgium); Vynckier, Stefaan [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Département de Radiothérapie, Cliniques Universitaires Saint-Luc, Avenue Hippocrate 54, 1200 Brussels (Belgium)] [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Département de Radiothérapie, Cliniques Universitaires Saint-Luc, Avenue Hippocrate 54, 1200 Brussels (Belgium); Bouchard, Hugo [Département de radio-oncologie, Centre hospitalier de l’Université de Montréal (CHUM), 1560 Sherbrooke est, Montréal, Québec H2L 4M1 (Canada)] [Département de radio-oncologie, Centre hospitalier de l’Université de Montréal (CHUM), 1560 Sherbrooke est, Montréal, Québec H2L 4M1 (Canada)
2014-01-15T23:59:59.000Z
Purpose: In the scope of reference dosimetry of radiotherapy beams, Monte Carlo (MC) simulations are widely used to compute ionization chamber dose response accurately. Uncertainties related to the transport algorithm can be verified performing self-consistency tests, i.e., the so-called “Fano cavity test.” The Fano cavity test is based on the Fano theorem, which states that under charged particle equilibrium conditions, the charged particle fluence is independent of the mass density of the media as long as the cross-sections are uniform. Such tests have not been performed yet for MC codes simulating proton transport. The objectives of this study are to design a new Fano cavity test for proton MC and to implement the methodology in two MC codes: Geant4 and PENELOPE extended to protons (PENH). Methods: The new Fano test is designed to evaluate the accuracy of proton transport. Virtual particles with an energy ofE{sub 0} and a mass macroscopic cross section of (?)/(?) are transported, having the ability to generate protons with kinetic energy E{sub 0} and to be restored after each interaction, thus providing proton equilibrium. To perform the test, the authors use a simplified simulation model and rigorously demonstrate that the computed cavity dose per incident fluence must equal (?E{sub 0})/(?) , as expected in classic Fano tests. The implementation of the test is performed in Geant4 and PENH. The geometry used for testing is a 10 × 10 cm{sup 2} parallel virtual field and a cavity (2 × 2 × 0.2 cm{sup 3} size) in a water phantom with dimensions large enough to ensure proton equilibrium. Results: For conservative user-defined simulation parameters (leading to small step sizes), both Geant4 and PENH pass the Fano cavity test within 0.1%. However, differences of 0.6% and 0.7% were observed for PENH and Geant4, respectively, using larger step sizes. For PENH, the difference is attributed to the random-hinge method that introduces an artificial energy straggling if step size is not small enough. Conclusions: Using conservative user-defined simulation parameters, both PENH and Geant4 pass the Fano cavity test for proton transport. Our methodology is applicable to any kind of charged particle, provided that the considered MC code is able to track the charged particle considered.
Fission matrix-based Monte Carlo criticality analysis of fuel storage pools
Farlotti, M. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Ecole Polytechnique, Palaiseau, F 91128 (France); Larsen, E. W. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)
2013-07-01T23:59:59.000Z
Standard Monte Carlo transport procedures experience difficulties in solving criticality problems in fuel storage pools. Because of the strong neutron absorption between fuel assemblies, source convergence can be very slow, leading to incorrect estimates of the eigenvalue and the eigenfunction. This study examines an alternative fission matrix-based Monte Carlo transport method that takes advantage of the geometry of a storage pool to overcome this difficulty. The method uses Monte Carlo transport to build (essentially) a fission matrix, which is then used to calculate the criticality and the critical flux. This method was tested using a test code on a simple problem containing 8 assemblies in a square pool. The standard Monte Carlo method gave the expected eigenfunction in 5 cases out of 10, while the fission matrix method gave the expected eigenfunction in all 10 cases. In addition, the fission matrix method provides an estimate of the error in the eigenvalue and the eigenfunction, and it allows the user to control this error by running an adequate number of cycles. Because of these advantages, the fission matrix method yields a higher confidence in the results than standard Monte Carlo. We also discuss potential improvements of the method, including the potential for variance reduction techniques. (authors)
Howard, M; Beltran, C; Herman, M [Mayo Clinic, Rochester, MN (United States)
2014-06-01T23:59:59.000Z
Purpose: To investigate the influence of the minimum monitor unit (MU) on the quality of clinical treatment plans for scanned proton therapy. Methods: Delivery system characteristics limit the minimum number of protons that can be delivered per spot, resulting in a min-MU limit. Plan quality can be impacted by the min-MU limit. Two sites were used to investigate the impact of min-MU on treatment plans: pediatric brain tumor at a depth of 5-10 cm; a head and neck tumor at a depth of 1-20 cm. Three field intensity modulated spot scanning proton plans were created for each site with the following parameter variations: min-MU limit range of 0.0000-0.0060; and spot spacing range of 0.5-2.0? of the nominal spot size at isocenter in water (?=4mm in this work). Comparisons were based on target homogeneity and normal tissue sparing. Results: The increase of the min-MU with a fixed spot spacing decreases plan quality both in homogeneous target coverage and in the avoidance of critical structures. Both head and neck and pediatric brain plans show a 20% increase in relative dose for the hot spot in the CTV and 10% increase in key critical structures when comparing min-MU limits of 0.0000 and 0.0060 with a fixed spot spacing of 1?. The DVHs of CTVs show min-MU limits of 0.0000 and 0.0010 produce similar plan quality and quality decreases as the min-MU limit increases beyond 0.0020. As spot spacing approaches 2?, degradation in plan quality is observed when no min-MU limit is imposed. Conclusion: Given a fixed spot spacing of ? 1? of the spot size in water, plan quality decreases as min- MU increases greater than 0.0020. The effect of min-MU should be taken into consideration while planning spot scanning proton therapy treatments to realize its full potential.
Bradford, Willis Warren
1954-01-01T23:59:59.000Z
. ................ LITERATURE CITED ......................... ACKNOWLEDGMENTS ......................... TABLES Table page 1. Distribution of F2 progeny of ZJ?1 x Acala among angular leaf spot grades for number of days from inoculation to infection..................... ...................... .. 19 2. Distribution of F2 progeny of ZJ?1 x Deltapine among angular leaf spot grades for number of days from inocula? tion to infection ........................... ? ? ? ? ? 20 3* Distribution of the disease grades of individual plants in F2...
A Proposal for a Standard Interface Between Monte Carlo Tools And One-Loop Programs
Binoth, T.; /Edinburgh U.; Boudjema, F.; /Annecy, LAPP; Dissertori, G.; Lazopoulos, A.; /Zurich, ETH; Denner, A.; /PSI, Villigen; Dittmaier, S.; /Freiburg U.; Frederix, R.; Greiner, N.; Hoeche, Stefan; /Zurich U.; Giele, W.; Skands, P.; Winter, J.; /Fermilab; Gleisberg, T.; /SLAC; Archibald, J.; Heinrich, G.; Krauss, F.; Maitre, D.; /Durham U., IPPP; Huber, M.; /Munich, Max Planck Inst.; Huston, J.; /Michigan State U.; Kauer, N.; /Royal Holloway, U. of London; Maltoni, F.; /Louvain U., CP3 /Milan Bicocca U. /INFN, Turin /Turin U. /Granada U., Theor. Phys. Astrophys. /CERN /NIKHEF, Amsterdam /Heidelberg U. /Oxford U., Theor. Phys.
2011-11-11T23:59:59.000Z
Many highly developed Monte Carlo tools for the evaluation of cross sections based on tree matrix elements exist and are used by experimental collaborations in high energy physics. As the evaluation of one-loop matrix elements has recently been undergoing enormous progress, the combination of one-loop matrix elements with existing Monte Carlo tools is on the horizon. This would lead to phenomenological predictions at the next-to-leading order level. This note summarises the discussion of the next-to-leading order multi-leg (NLM) working group on this issue which has been taking place during the workshop on Physics at TeV Colliders at Les Houches, France, in June 2009. The result is a proposal for a standard interface between Monte Carlo tools and one-loop matrix element programs.
Monte Carlo implementation of a guiding-center Fokker-Planck kinetic equation
Hirvijoki, E.; Snicker, A.; Kurki-Suonio, T. [Department of Applied Physics, Aalto University, FI-00076 Aalto (Finland)] [Department of Applied Physics, Aalto University, FI-00076 Aalto (Finland); Brizard, A. [Department of Physics, Saint Michael's College, Colchester, Vermont 05439 (United States)] [Department of Physics, Saint Michael's College, Colchester, Vermont 05439 (United States)
2013-09-15T23:59:59.000Z
A Monte Carlo method for the collisional guiding-center Fokker-Planck kinetic equation is derived in the five-dimensional guiding-center phase space, where the effects of magnetic drifts due to the background magnetic field nonuniformity are included. It is shown that, in the limit of a homogeneous magnetic field, our guiding-center Monte Carlo collision operator reduces to the guiding-center Monte Carlo Coulomb operator previously derived by Xu and Rosenbluth [Phys. Fluids B 3, 627 (1991)]. Applications of the present work will focus on the collisional transport of energetic ions in complex nonuniform magnetized plasmas in the large mean-free-path (collisionless) limit, where magnetic drifts must be retained.
Data decomposition of Monte Carlo particle transport simulations via tally servers
Romano, Paul K., E-mail: paul.k.romano@gmail.com [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Siegel, Andrew R., E-mail: siegala@mcs.anl.gov [Argonne National Laboratory, Theory and Computing Sciences, 9700 S Cass Ave., Argonne, IL 60439 (United States); Forget, Benoit, E-mail: bforget@mit.edu [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)] [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Smith, Kord, E-mail: kord@mit.edu [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)] [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)
2013-11-01T23:59:59.000Z
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 nodes into tracking processors and tally servers. The former are used to simulate the movement of particles through the domain while the latter continuously receive and update tally data. A performance model for this approach is developed, suggesting that, for a range of parameters relevant to LWR analysis, the tally server algorithm should perform with minimal overhead on contemporary supercomputers. An implementation of the algorithm in OpenMC is then tested on the Intrepid and Titan supercomputers, supporting the key predictions of the model over a wide range of parameters. We thus conclude that the tally server algorithm is a successful approach to circumventing classical on-node memory constraints en route to unprecedentedly detailed Monte Carlo reactor simulations.
Crossing the mesoscale no-mans land via parallel kinetic Monte Carlo.
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
2009-10-01T23:59:59.000Z
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.
General purpose dynamic Monte Carlo with continuous energy for transient analysis
Sjenitzer, B. L.; Hoogenboom, J. E. [Delft Univ. of Technology, Dept. of Radiation, Radionuclide and Reactors, Mekelweg 15, 2629JB Delft (Netherlands)
2012-07-01T23:59:59.000Z
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)
Calculation of radiation therapy dose using all particle Monte Carlo transport
Chandler, William P. (Tracy, CA); Hartmann-Siantar, Christine L. (San Ramon, CA); Rathkopf, James A. (Livermore, CA)
1999-01-01T23:59:59.000Z
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.
Calculation of radiation therapy dose using all particle Monte Carlo transport
Chandler, W.P.; Hartmann-Siantar, C.L.; Rathkopf, J.A.
1999-02-09T23:59:59.000Z
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. 57 figs.
Advanced Mesh-Enabled Monte carlo capability for Multi-Physics Reactor Analysis
Wilson, Paul; Evans, Thomas; Tautges, Tim
2012-12-24T23:59:59.000Z
This project will accumulate high-precision fluxes throughout reactor geometry on a non- orthogonal grid of cells to support multi-physics coupling, in order to more accurately calculate parameters such as reactivity coefficients and to generate multi-group cross sections. This work will be based upon recent developments to incorporate advanced geometry and mesh capability in a modular Monte Carlo toolkit with computational science technology that is in use in related reactor simulation software development. Coupling this capability with production-scale Monte Carlo radiation transport codes can provide advanced and extensible test-beds for these developments. Continuous energy Monte Carlo methods are generally considered to be the most accurate computational tool for simulating radiation transport in complex geometries, particularly neutron transport in reactors. Nevertheless, there are several limitations for their use in reactor analysis. Most significantly, there is a trade-off between the fidelity of results in phase space, statistical accuracy, and the amount of computer time required for simulation. Consequently, to achieve an acceptable level of statistical convergence in high-fidelity results required for modern coupled multi-physics analysis, the required computer time makes Monte Carlo methods prohibitive for design iterations and detailed whole-core analysis. More subtly, the statistical uncertainty is typically not uniform throughout the domain, and the simulation quality is limited by the regions with the largest statistical uncertainty. In addition, the formulation of neutron scattering laws in continuous energy Monte Carlo methods makes it difficult to calculate adjoint neutron fluxes required to properly determine important reactivity parameters. Finally, most Monte Carlo codes available for reactor analysis have relied on orthogonal hexahedral grids for tallies that do not conform to the geometric boundaries and are thus generally not well-suited to coupling with the unstructured meshes that are used in other physics simulations.
An Advanced Neutronic Analysis Toolkit with Inline Monte Carlo capability for BHTR Analysis
William R. Martin; John C. Lee
2009-12-30T23:59:59.000Z
Monte Carlo capability has been combined with a production LWR lattice physics code to allow analysis of high temperature gas reactor configurations, accounting for the double heterogeneity due to the TRISO fuel. The Monte Carlo code MCNP5 has been used in conjunction with CPM3, which was the testbench lattice physics code for this project. MCNP5 is used to perform two calculations for the geometry of interest, one with homogenized fuel compacts and the other with heterogeneous fuel compacts, where the TRISO fuel kernels are resolved by MCNP5.
Monte Carlo simulations of the HP model (the "Ising model" of protein folding)
Li, Ying Wai; Landau, David P; 10.1016/j.cpc.2010.12.049
2011-01-01T23:59:59.000Z
Using Wang-Landau sampling with suitable Monte Carlo trial moves (pull moves and bond-rebridging moves combined) we have determined the density of states and thermodynamic properties for a short sequence of the HP protein model. For free chains these proteins are known to first undergo a collapse "transition" to a globule state followed by a second "transition" into a native state. When placed in the proximity of an attractive surface, there is a competition between surface adsorption and folding that leads to an intriguing sequence of "transitions". These transitions depend upon the relative interaction strengths and are largely inaccessible to "standard" Monte Carlo methods.
FREYA-a new Monte Carlo code for improved modeling of fission chains
Hagmann, C A; Randrup, J; Vogt, R L
2012-06-12T23:59:59.000Z
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.
Matching NLO QCD with parton shower in Monte Carlo scheme - the KrkNLO method
S. Jadach; W. Placzek; S. Sapeta; A. Siodmok; M. Skrzypek
2015-05-11T23:59:59.000Z
A new method of including the complete NLO QCD corrections to hard processes in the LO parton-shower Monte Carlo (PSMC) is presented. This method, called KrkNLO, requires the use of parton distribution functions in a dedicated Monte Carlo factorization scheme, which is also discussed in this paper. In the future, it may simplify introduction of the NNLO corrections to hard processes and the NLO corrections to PSMC. Details of the method and numerical examples of its practical implementation, as well as comparisons with other calculations, such as MCFM, MC@NLO, POWHEG, for single $Z/\\gamma^*$-boson production at the LHC, are presented.
A Look at general cavity theory through a code incorporating Monte Carlo techniques
Weyland, Mark Duffy
1989-01-01T23:59:59.000Z
A LOOK AT GENERAL CAVITY THEORY THROUGH A CODE INCORPORATING MONTE CARLO TECHNIQUES A Thesis by MARK DUFFY WEYLAND Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 1989 Major Subject: Health Physics A LOOK AT GENERAL CAVITY THEORY THROUGH A CODE INCORPORATING MONTE CARLO TECHNIQUES A Thesis by MARK DUFFY WEYLAND Approved as to style and content by: I hn W. Po ton air of Committee...
Anderson, James B.
Direct Monte Carlo simulation of chemical reaction systems: Internal energy transfer and an energy a direct Monte Carlo simulation of an energy-dependent t&molecular reaction system of the type A+ B simulation of a unimo- lecular reaction with an energy-dependent rate constant k3 and with explicit treatment
Wu, Zhigang
Quantum Monte Carlo calculations of the energy-level alignment at hybrid interfaces: Role of many; published 29 May 2009 An approach is presented for obtaining a highly accurate description of the energy-level alignment at hybrid interfaces, using quantum Monte Carlo calculations to include many-body effects
Sailhac, Pascal
Inversion of surface nuclear magnetic resonance data by an adapted Monte Carlo method applied, France Abstract Inversion of surface nuclear magnetic resonance (SNMR) provides important information Science B.V. All rights reserved. Keywords: Inversion; Surface nuclear magnetic resonance; Monte Carlo 1
Mezei, Mihaly
An improved acceptance criterion for local move Monte Carlo method in which trial steps change only sevenEfficient Monte Carlo sampling for long molecular chains using local moves, tested on a solvated, New York University, New York, New York 10029 Received 20 February 2002; accepted 27 November 2002
Journal of Statistical Physics, Vol. 89, Nos. 5/6, 1997 Simulated Annealing Using Hybrid Monte Carlo
Toral, Raúl
of the system. It is known that if a system is heated to a very high temperature T and then it is slowly cooledJournal of Statistical Physics, Vol. 89, Nos. 5/6, 1997 Simulated Annealing Using Hybrid Monte global actualizationsvia the hybrid Monte Carloalgorithmin theirgeneralizedversion for the proposal
Chung, Kiwhan
1996-01-01T23:59:59.000Z
While the use of Monte Carlo method has been prevalent in nuclear engineering, it has yet to fully blossom in the study of solute transport in porous media. By using an etched-glass micromodel, an attempt is made to apply Monte Carlo method...
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Kellogg, Christina A.; Piceno, Yvette M.; Tom, Lauren M.; DeSantis, Todd Z.; Gray, Michael A.; Andersen, Gary L.; Mormile, Melanie R.
2014-10-07T23:59:59.000Z
Coral disease is one of the major causes of reef degradation. Dark Spot Syndrome (DSS) was described in the early 1990's as brown or purple amorphous areas of tissue on a coral and has since become one of the most prevalent diseases reported on Caribbean reefs. It has been identified in a number of coral species, but there is debate as to whether it is in fact the same disease in different corals. Further, it is questioned whether these macroscopic signs are in fact diagnostic of an infectious disease at all. The most commonly affected species in the Caribbean ismore »the massive starlet coral Siderastrea siderea. We sampled this species in two locations, Dry Tortugas National Park and Virgin Islands National Park. Tissue biopsies were collected from both healthy colonies and those with dark spot lesions. Microbial-community DNA was extracted from coral samples (mucus, tissue, and skeleton), amplified using bacterial-specific primers, and applied to PhyloChip G3 microarrays to examine the bacterial diversity associated with this coral. Samples were also screened for the presence of a fungal ribotype that has recently been implicated as a causative agent of DSS in another coral species, but the amplifications were unsuccessful. S. siderea samples did not cluster consistently based on health state (i.e., normal versus dark spot). Various bacteria, including Cyanobacteria and Vibrios, were observed to have increased relative abundance in the discolored tissue, but the patterns were not consistent across all DSS samples. Overall, our findings do not support the hypothesis that DSS in S. siderea is linked to a bacterial pathogen or pathogens. This dataset provides the most comprehensive overview to date of the bacterial community associated with the scleractinian coral S. siderea.« less
NONE
1998-01-01T23:59:59.000Z
The Bear Creek Valley Floodplain Hot Spot Removal Action Project Plan, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee (Y/ER-301) was prepared (1) to safely, cost-effectively, and efficiently evaluate the environmental impact of solid material in the two debris areas in the context of industrial land uses (as defined in the Bear Creek Valley Feasibility Study) to support the Engineering Evaluation/Cost Assessment and (2) to evaluate, define, and implement the actions to mitigate these impacts. This work was performed under Work Breakdown Structure 1.x.01.20.01.08.
A Scalable Parallel Monte Carlo Method for Free Energy Simulations of Molecular Systems
Chan, Derek Y C
A Scalable Parallel Monte Carlo Method for Free Energy Simulations of Molecular Systems MALEK O for problems where the energy dominates the entropy. An example is parallel tempering, in which simulations the free energy of the system as a direct output of the simulation. Traditional Metropolis MC samples phase
Introduction to Markov Chain Monte Carlo Simulations and their Statistical Analysis
Bernd A. Berg
2004-10-19T23:59:59.000Z
This article is a tutorial on Markov chain Monte Carlo simulations and their statistical analysis. The theoretical concepts are illustrated through many numerical assignments from the author's book on the subject. Computer code (in Fortran) is available for all subjects covered and can be downloaded from the web.
Monte Carlo study of a luminosity detector for the International Linear Collider
H. Abramowicz; R. Ingbir; S. Kananov; A. Levy
2005-08-11T23:59:59.000Z
This paper presents the status of Monte Carlo simulation of one of the luminosity detectors considered for the future e+e- International Linear Collider (ILC). The detector consists of a tungsten/silicon sandwich calorimeter with pad readout. The study was performed for Bhabha scattering events assuming a zero crossing angle for the beams.
Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study
Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study 11 January 2006; published 22 February 2006 Proton computed tomography pCT has been explored computed tomography pCT has several potential ad- vantages in medical applications. Its favorable dose
Collective enhancement of nuclear state densities by the shell model Monte Carlo approach
C. Özen; Y. Alhassid; H. Nakada
2015-01-22T23:59:59.000Z
The shell model Monte Carlo (SMMC) approach allows for the microscopic calculation of statistical and collective properties of heavy nuclei using the framework of the configuration-interaction shell model in very large model spaces. We present recent applications of the SMMC method to the calculation of state densities and their collective enhancement factors in rare-earth nuclei.
MonteCarloType Techniques for Processing Interval Uncertainty, and Their Geophysical and
Ward, Karen
MonteCarloType Techniques for Processing Interval Uncertainty, and Their Geophysical contact email vladik@cs.utep.edu Abstract To determine the geophysical structure of a region, we measure are independently normally distributed. Problem: the resulting accuracies are not in line with geophysical intuition
Monte-Carlo-Type Techniques for Processing Interval Uncertainty, and Their Geophysical and
Ward, Karen
Monte-Carlo-Type Techniques for Processing Interval Uncertainty, and Their Geophysical contact email vladik@cs.utep.edu Abstract To determine the geophysical structure of a region, we measure are independently normally distributed. Problem: the resulting accuracies are not in line with geophysical intuition
First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo
Anderson, James B.
First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo Arne Lu, Pennsylvania 16802 Received 20 May 1996; accepted 24 July 1996 Accurate ground state energies comparable FN-DQMC method. The residual energy, the nodal error due to the error in the nodal structure
A Combined Density Functional and Monte Carlo Study of Polycarbonate R. O. Jones and P. Ballone[*
A Combined Density Functional and Monte Carlo Study of Polycarbonate R. O. Jones and P. Ballone and reactivity for organic systems closely related to bisphenol-A-polycarbonate(BPA- PC). The results provide a detailed description of polymers, using bisphenol A polycarbonate (BPA- PC) as an example
Multivariate Population Balances via Moment and Monte Carlo Simulation Methods: An Important Sol application of current/future importance, a multivariate description is required, for which the existing, hopefully, motivate a broader attack on important multivariate population balance problems, including those
Alfè, Dario
Structural properties and enthalpy of formation of magnesium hydride from quantum Monte Carlo calculations to study the structural properties of magnesium hydride MgH2 , including the pressure. INTRODUCTION The energetics of metal hydrides has recently become an issue of large scientific
Thermodynamics and quark susceptibilities: a Monte-Carlo approach to the PNJL model
Weise, Wolfram
Thermodynamics and quark susceptibilities: a Monte-Carlo approach to the PNJL model M on the thermodynamics of the model, both in the case of pure gauge theory and including two quark flavors. In the two- flavor case, we calculate the second-order Taylor expansion coefficients of the thermodynamic grand
Explicit estimation of higher order modes in fission source distribution of Monte-Carlo calculation
Yamamoto, A.; Sakata, K.; Endo, T. [Nagoya University, Department of Materials, Physics and Energy Engineering, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)
2013-07-01T23:59:59.000Z
Magnitude of higher order modes in fission source distribution of a multi-group Monte-Carlo calculation is estimated using the orthogonal property of forward and adjoint fission source distributions. Calculation capability of the forward and adjoint fission source distributions for fundamental and higher order modes are implemented in the AEGIS code, which is a two-dimensional transport code based on the method of characteristics. With the calculation results of the AEGIS code, magnitudes of the first to fifth higher order modes in fission source distribution obtained by the multi-group Monte-Carlo code GMVP are estimated. There are two contributions in the present study - (1) establishment of a surrogate model, which represents convergence of fission source distribution taking into account the inherent statistical 'noise' of higher order modes of Monte-Carlo calculations and (2) independent confirmation of the estimated dominance ratio in a Monte-Carlo calculation. The surrogate model would contribute to studies of the inter-cycle correlation and estimation of sufficient number of inactive/active cycles. (authors)
Dose distribution close to metal implants in Gamma Knife Radiosurgery: A Monte Carlo study
Yu, K.N.
Detachable Coil GDC system was used to localize and obliterate the aneurysm.5 Soft platinum coils were8 II. METHODOLOGY The Monte Carlo system employed is the PRESTA Pa- rameter Reduced Electron be predicted correctly by the present treatment planning system, GammaPlan,1 be- cause the calculations
Bayes and Big Data: The Consensus Monte Carlo Algorithm Steven L. Scott1
Cortes, Corinna
Bayes and Big Data: The Consensus Monte Carlo Algorithm Steven L. Scott1 , Alexander W. Blocker1 of Business October 31, 2013 Abstract A useful definition of "big data" is data that is too big to comfortably by splitting data across multiple machines. Communication between large numbers of machines is expensive
Hale, Barbara N.
CALCULATION OF SCALED NUCLEATION RATES FOR WATER USING MONTE CARLO GENERATED CLUSTER FREE ENERGYMattio All Rights Reserved #12;iii ABSTRACT Helmholtz free energy differences, -dFn , are calculated inconsistent with the experimental properties of water. Summation of the scaled TIP4P free energy differences
Monte Carlo simulation of electron transport in degenerate and inhomogeneous semiconductors
Monte Carlo simulation of electron transport in degenerate and inhomogeneous semiconductors Mona concentrations up to 1020 cm-3 . De- generate semiconductors are important for thermoelectric and thermionic transport in degenerate semiconductor-based structures. If the electron wavelength is smaller than
K-effective of the world: and other concerns for Monte Carlo Eigenvalue calculations
Brown, Forrest B [Los Alamos National Laboratory
2010-01-01T23:59:59.000Z
Monte Carlo methods have been used to compute k{sub eff} and the fundamental model eigenfunction of critical systems since the 1950s. Despite the sophistication of today's Monte Carlo codes for representing realistic geometry and physics interactions, correct results can be obtained in criticality problems only if users pay attention to source convergence in the Monte Carlo iterations and to running a sufficient number of neutron histories to adequately sample all significant regions of the problem. Recommended best practices for criticality calculations are reviewed and applied to several practical problems for nuclear reactors and criticality safety, including the 'K-effective of the World' problem. Numerical results illustrate the concerns about convergence and bias. The general conclusion is that with today's high-performance computers, improved understanding of the theory, new tools for diagnosing convergence (e.g., Shannon entropy of the fission distribution), and clear practical guidance for performing calculations, practitioners will have a greater degree of confidence than ever of obtaining correct results for Monte Carlo criticality calculations.
Monte Carlo Simulation of Alzheimer's Disease in the United States: 2010-2060
Feres, Renato
Monte Carlo Simulation of Alzheimer's Disease in the United States: 2010-2060 Michael Blech concerns facing the United States over the next 50 years. This progressive disease is currently the sixth on the United States population, and second, the simulation models both prevalence and mortality. Both
Sequential Monte Carlo in Model Comparison: Example in Cellular Dynamics in Systems Biology
Richardson, David
: American Statistical Association (2009): 1274-1287. Abstract Sequential Monte Carlo analysis of time series. Mukherjee L. You M. West -- Published in: JSM Proceedings/Bayesian Statistical Science. Alexandria, VA statistical model assessment is really just beginning in this new field. Single cell time series data
A new approach to Monte Carlo simulations in statistical physics: Wang-Landau sampling
Holzwarth, Natalie
it to models exhibiting first-order or second-order phase transitions. © 2004 American Association of PhysicsA new approach to Monte Carlo simulations in statistical physics: Wang-Landau sampling D. P. Landau for doing simulations in classical statistical physics in a different way. Instead of sampling
NUCLEOSYNTHESIS IN THE EARLY GALAXY F. Montes,1,2,3
Cowan, John
NUCLEOSYNTHESIS IN THE EARLY GALAXY F. Montes,1,2,3 T. C. Beers,2,4 J. Cowan,5 T. Elliot,2,3,6 K the observations. Subject headinggs: Galaxy: abundances -- nuclear reactions, nucleosynthesis, abundances -- stars-abundances and subtracting them from the observed solar system abundances. If there is an addi- tional nucleosynthesis
arXiv:physics/000104722Jan2000 Path Integral Monte Carlo Calculation of the Deuterium Hugoniot
Militzer, Burkhard
arXiv:physics/000104722Jan2000 Path Integral Monte Carlo Calculation of the Deuterium Hugoniot B University of Illinois at Urbana-Champaign, Urbana, IL 61801 (January 21, 2000) Restricted path integral of the path integral. Further, we compare the results obtained with a free particle nodal restriction
Calculating Risk of Cost Using Monte Carlo Simulations with Fuzzy Parameters in Civil Engineering
Pownuk, Andrzej
Calculating Risk of Cost Using Monte Carlo Simulations with Fuzzy Parameters in Civil Engineering MICHAL BE¸TKOWSKI Department of Civil Engineering, Silesian University of Technology,Gliwice, Poland, mb@zeus.polsl.gliwice.pl ANDRZEJ POWNUK Department of Civil Engineering, Silesian University of Technology,Gliwice, Poland, pownuk
Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay,
Boyer, Edmond
Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay At least 100 fish species are known to be present in the intertidal areas (estuaries, mudflats and salt, such as estuaries and lagoons, play a nursery role for many fish species. However, in Europe little attention has
Performance Characteristics of Cathode Materials for Lithium-Ion Batteries: A Monte Carlo Strategy
Subramanian, Venkat
Performance Characteristics of Cathode Materials for Lithium-Ion Batteries: A Monte Carlo Strategy to study the performance of cathode materials in lithium-ion batteries. The methodology takes into account. Published September 26, 2008. Lithium-ion batteries are state-of-the-art power sources1 for por- table
Monte Carlo Tree Search for Simulated Car Racing Jacob Fischer1
Togelius, Julian
(TORCS) is a popular platform for experimenting with different AI methods in car racing. A va- rietyMonte Carlo Tree Search for Simulated Car Racing Jacob Fischer1 , Nikolaj Falsted1 , Mathias be modified to achieve this. In this paper, we investi- gate the application of MCTS to simulated car racing
Study of CANDU Thorium-based Fuel Cycles by Deterministic and Monte Carlo Methods
Paris-Sud XI, Université de
Study of CANDU Thorium-based Fuel Cycles by Deterministic and Monte Carlo Methods A. Nuttin1 , P, there is a renewal of interest in self-sustainable thorium fuel cycles applied to various concepts such as Molten here, with a shorter term view, to re-evaluate the economic competitiveness of once-through thorium
The polarized emissivity of a wind-roughened sea surface: A Monte Carlo model
Theiler, James
The polarized emissivity of a wind-roughened sea surface: A Monte Carlo model Bradley G. Henderson-infrared emissivity of a wind-roughened sea surface. The model includes the effects of both shadowing and the reflected component of surface emission. By using Stokes vectors to quantify the radiation along a given ray
Quantum Monte Carlo study of a disordered 2D Josephson junction array
Stroud, David
Quantum Monte Carlo study of a disordered 2D Josephson junction array W.A. Al-Saidi *, D. Stroud not be established even * Corresponding author. E-mail addresses: al-saidi.1@osu.edu (W.A. Al-Saidi), stroud
Sequential Monte Carlo for Simultaneous Passive Device-Free Tracking and Sensor Localization Using
Rabbat, Michael
Sequential Monte Carlo for Simultaneous Passive Device-Free Tracking and Sensor Localization Using Men Beijing Univ. Posts & Telecom. Beijing, China menad@bupt.edu.cn ABSTRACT This paper presents and evaluates a method for simulta- neously tracking a target while localizing the sensor nodes of a passive
A Methodological Comparison of Monte Carlo Simulation and Epoch-Era Analysis for
de Weck, Olivier L.
techniques, morphological analysis, scenario planning · Semi-quantitative methods (can be used to initialize%) Probabilistic risk assessment (PRA), Fault Tree Analysis (FTA), Hazards Analysis (HA), Failure modes and effectsA Methodological Comparison of Monte Carlo Simulation and Epoch-Era Analysis for Tradespace
Ryan, Dominic
Monte Carlo simulations of transverse spin freezing in the three-dimensional frustrated Heisenberg of the spins freeze leading to a noncollinear spin structure dominated by ferromagnetic correlations. The phase as the transverse degrees of freedom order.' Theoretical support for a transverse spin freezing tran- sition
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
rates exchange rates weather electricity/gas demand crude oil prices . . . Mike Giles (Oxford) Monte In computational finance, stochastic differential equations are used to model the behaviour of stocks interest31, 2013 5 / 33 #12;SDEs in Finance Examples: Geometric Brownian motion (Black-Scholes model for stock
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
exchange rates weather electricity/gas demand crude oil prices . . . Mike Giles (Oxford) Monte Carlo finance, stochastic differential equations are used to model the behaviour of stocks interest rates in Finance Examples: Geometric Brownian motion (Black-Scholes model for stock prices) dS = r S dt + S dW Cox
A Monte Carlo Method Used for the Identification of the Muscle Spindle
Rigas, Alexandros
the behavior of the muscle spindle by using a logistic regression model. The system receives input from. Key words: Exact logistic regression, likelihood function, Monte Carlo technique, muscle spin- dle. 21 is part of the skeletal muscles and is responsible for the initiation of move- ment and the maintenance
Ilan, Boaz
Monte-Carlo simulations of photon transport to predict the performance of LSCs based on "type-II" CdSe. In addition, when the LSC has CdSe-CdTe nanorods that are aligned perpendicular to the top surface, the escape.1063/1.3619809] I. INTRODUCTION Photovoltaic (PV) solar cells have become much more efficient over the past few
Usefulness of the reversible jump Markov chain Monte Carlo model in regional flood frequency
Ribatet, Mathieu
Usefulness of the reversible jump Markov chain Monte Carlo model in regional flood frequency; revised 3 May 2007; accepted 17 May 2007; published 3 August 2007. [1] Regional flood frequency analysis and the index flood approach. Results show that the proposed estimator is absolutely suited to regional
Instabilities in Molecular Dynamics Integrators used in Hybrid Monte Carlo Simulations
B. Joo; UKQCD Collaboration
2001-10-11T23:59:59.000Z
We discuss an instability in the leapfrog integration algorithm, widely used in current Hybrid Monte Carlo (HMC) simulations of lattice QCD. We demonstrate the instability in the simple harmonic oscillator (SHO) system where it is manifest. We demonstrate the instability in HMC simulations of lattic QCD with dynamical Wilson-Clover fermions and discuss implications for future simulations of lattice QCD.
Use of single scatter electron monte carlo transport for medical radiation sciences
Svatos, Michelle M. (Oakland, CA)
2001-01-01T23:59:59.000Z
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.
Monte Carlo Adaptive Technique for Sensitivity Analysis of a Large-scale Air Pollution Model
Dimov, Ivan
Monte Carlo Adaptive Technique for Sensitivity Analysis of a Large-scale Air Pollution Model Ivan of input parameters contribution into output variability of a large- scale air pollution model]. This model simulates the transport of air pollutants and has been developed by Dr. Z. Zlatev and his
Autologistic Regression Analysis of Spatial-Temporal Binary Data via Monte Carlo
Aukema, Brian
Autologistic Regression Analysis of Spatial-Temporal Binary Data via Monte Carlo Maximum Likelihood regression analysis of binary data that are measured on a spatial lattice and repeatedly over discrete time points. We propose a spatial- temporal autologistic regression model and draw statistical inference via
Baes, Maarten
2008-01-01T23:59:59.000Z
that is inherent in Monte Carlo radiative transfer simulations. As the typical detectors used in Monte Carlo negligible, we recommend the use of smart detectors in Monte Carlo radiative transfer simulations. Key wordsMon. Not. R. Astron. Soc. 391, 617623 (2008) doi:10.1111/j.1365-2966.2008.13941.x Smart detectors
Paris-Sud XI, Université de
, France and its relationship with Mont-Blanc glacier fluctuations M., Debret1, 2 , E., Chapron3, 2 , M large glaciers from the Mont Blanc Massif, and fluctuations in Rhone River flood supply in Lake Le Bourget is interpreted as resulting essentially from Mont Blanc Glacier activity during the Holocene
MHD processes during the cascade development of the neck and hot spot in an X-pinch
Ivanenkov, G. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Stepniewski, W. [Kaliski Institute of Plasma Physics and Laser Microfusion (Poland); Gus'kov, S. Yu. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
2008-08-15T23:59:59.000Z
Results are presented from two-dimensional MHD simulations of X-pinch implosion. The simulations were performed in the (r, z) and (x, y) geometries for homogeneous (dense plasma) and heterogeneous (core-corona) loads. The formation of a minidiode, the development of a neck and an X-radiating hot spot, and the influence of the plasma corona on the implosion dynamics of the dense X-pinch plasma were investigated. For through simulations, the conical neck model was used, whereas a detailed analysis of the X-ray burst was performed in the parabolic neck model. The MHD processes occurring during the implosion of oblique shock waves and the onset of instability of the plasma column were examined. It is found that, due to the quasi-periodic character of these processes, the neck compression proceeds in a cascade fashion. The plasma state in a hot spot just before the break of the neck is analyzed, and the possibility of generating fast particle beams is considered.
Takahiro Mizusaki; Noritaka Shimizu
2012-01-27T23:59:59.000Z
We propose a new variational Monte Carlo (VMC) method with an energy variance extrapolation for large-scale shell-model calculations. This variational Monte Carlo is a stochastic optimization method with a projected correlated condensed pair state as a trial wave function, and is formulated with the M-scheme representation of projection operators, the Pfaffian and the Markov-chain Monte Carlo (MCMC). Using this method, we can stochastically calculate approximated yrast energies and electro-magnetic transition strengths. Furthermore, by combining this VMC method with energy variance extrapolation, we can estimate exact shell-model energies.
Smart, Simon Daniel
2014-02-04T23:59:59.000Z
The use of spin-pure and non-orthogonal Hilbert spaces in Full Configuration Interaction Quantum Monte–Carlo Simon Smart Trinity College This dissertation is submitted for the degree of Doctor of Philosophy at the University of Cambridge, December... 2013 For my mother Diana Jean Smart 1956-2013 The use of spin-pure and non-orthogonal Hilbert spaces in Full Configuration Interaction Quantum Monte–Carlo Simon Smart Abstract Full Configuration Interaction Quantum Monte–Carlo (FCIQMC) al- lows...
MCViNE -- An object oriented Monte Carlo neutron ray tracing simulation package
Lin, Jiao Y Y; Granroth, Garrett E; Abernathy, Douglas L; Lumsden, Mark D; Winn, Barry; Aczel, Adam A; Aivazis, Michael; Fultz, Brent
2015-01-01T23:59:59.000Z
MCViNE (Monte-Carlo VIrtual Neutron Experiment) is a versatile Monte Carlo (MC) neutron ray-tracing program that provides researchers with tools for performing computer modeling and simulations that mirror real neutron scattering experiments. By adopting modern software engineering practices such as using composite and visitor design patterns for representing and accessing neutron scatterers, and using recursive algorithms for multiple scattering, MCViNE is flexible enough to handle sophisticated neutron scattering problems including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can take advantage of simulation components in linear-chain-based MC ray tracing packages widely used in instrument design and optimization, as well as NumPy-based components that make prototypes useful and easy to develop. These developments have enabled us to carry out detailed simulations of neutron scatteri...
The energy injection and losses in the Monte Carlo simulations of a diffusive shock
Wang, Xin
2011-01-01T23:59:59.000Z
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...
Miura, Shinichi [Institute for Molecular Science, 38 Myodaiji, Okazaki 444-8585 (Japan)
2007-03-21T23:59:59.000Z
In this paper, we present a path integral hybrid Monte Carlo (PIHMC) method for rotating molecules in quantum fluids. This is an extension of our PIHMC for correlated Bose fluids [S. Miura and J. Tanaka, J. Chem. Phys. 120, 2160 (2004)] to handle the molecular rotation quantum mechanically. A novel technique referred to be an effective potential of quantum rotation is introduced to incorporate the rotational degree of freedom in the path integral molecular dynamics or hybrid Monte Carlo algorithm. For a permutation move to satisfy Bose statistics, we devise a multilevel Metropolis method combined with a configurational-bias technique for efficiently sampling the permutation and the associated atomic coordinates. Then, we have applied the PIHMC to a helium-4 cluster doped with a carbonyl sulfide molecule. The effects of the quantum rotation on the solvation structure and energetics were examined. Translational and rotational fluctuations of the dopant in the superfluid cluster were also analyzed.
Rubery, M. S.; Horsfield, C. J. [Plasma Physics Department, AWE plc, Reading RG7 4PR (United Kingdom)] [Plasma Physics Department, AWE plc, Reading RG7 4PR (United Kingdom); Herrmann, H.; Kim, Y.; Mack, J. M.; Young, C.; Evans, S.; Sedillo, T.; McEvoy, A.; Caldwell, S. E. [Plasma Physics Department, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Plasma Physics Department, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Grafil, E.; Stoeffl, W. [Physics, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Physics, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Milnes, J. S. [Photek Limited UK, 26 Castleham Road, St. Leonards-on-sea TN38 9NS (United Kingdom)] [Photek Limited UK, 26 Castleham Road, St. Leonards-on-sea TN38 9NS (United Kingdom)
2013-07-15T23:59:59.000Z
The gas Cherenkov detectors at NIF and Omega measure several ICF burn characteristics by detecting multi-MeV nuclear ? emissions from the implosion. Of primary interest are ? bang-time (GBT) and burn width defined as the time between initial laser-plasma interaction and peak in the fusion reaction history and the FWHM of the reaction history respectively. To accurately calculate such parameters the collaboration relies on Monte Carlo codes, such as GEANT4 and ACCEPT, for diagnostic properties that cannot be measured directly. This paper describes a series of experiments performed at the High Intensity ? Source (HI?S) facility at Duke University to validate the geometries and material data used in the Monte Carlo simulations. Results published here show that model-driven parameters such as intensity and temporal response can be used with less than 50% uncertainty for all diagnostics and facilities.
Hard-sphere melting and crystallization with event-chain Monte Carlo
Isobe, Masaharu
2015-01-01T23:59:59.000Z
We simulate crystallization and melting with local Monte Carlo (LMC), event-chain Monte Carlo (ECMC), and with event-driven molecular dynamics (EDMD) in systems with up to one million three-dimensional hard spheres. We illustrate that our implementations of the three algorithms rigorously coincide in their equilibrium properties. We then study nucleation in the NVE ensemble from the fcc crystal into the homogeneous liquid phase and from the liquid into the homogeneous crystal. ECMC and EDMD both approach equilibrium orders of magnitude faster than LMC. ECMC is also notably faster than EDMD, especially for the equilibration into a crystal from a disordered initial condition at high density. ECMC can be trivially implemented for hard-sphere and for soft-sphere potentials, and we suggest possible applications of this algorithm for studying jamming and the physics of glasses, as well as disordered systems.
Rasch, Kevin M.; Hu, Shuming; Mitas, Lubos [Center for High Performance Simulation and Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)] [Center for High Performance Simulation and Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)
2014-01-28T23:59:59.000Z
We elucidate the origin of large differences (two-fold or more) in the fixed-node errors between the first- vs second-row systems for single-configuration trial wave functions in quantum Monte Carlo calculations. This significant difference in the valence fixed-node biases is studied across a set of atoms, molecules, and also Si, C solid crystals. We show that the key features which affect the fixed-node errors are the differences in electron density and the degree of node nonlinearity. The findings reveal how the accuracy of the quantum Monte Carlo varies across a variety of systems, provide new perspectives on the origins of the fixed-node biases in calculations of molecular and condensed systems, and carry implications for pseudopotential constructions for heavy elements.
M. A. Novotny; Shannon M. Wheeler
2002-11-02T23:59:59.000Z
We present the Monte Carlo with Absorbing Markov Chains (MCAMC) method for extremely long kinetic Monte Carlo simulations. The MCAMC algorithm does not modify the system dynamics. It is extremely useful for models with discrete state spaces when low-temperature simulations are desired. To illustrate the strengths and limitations of this algorithm we introduce a simple model involving random walkers on an energy landscape. This simple model has some of the characteristics of protein folding and could also be experimentally realizable in domain motion in nanoscale magnets. We find that even the simplest MCAMC algorithm can speed up calculations by many orders of magnitude. More complicated MCAMC simulations can gain further increases in speed by orders of magnitude.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Tringe, J. W.; Ileri, N.; Levie, H. W.; Stroeve, P.; Ustach, V.; Faller, R.; Renaud, P.
2015-08-01T23:59:59.000Z
We use Molecular Dynamics and Monte Carlo simulations to examine molecular transport phenomena in nanochannels, explaining four orders of magnitude difference in wheat germ agglutinin (WGA) protein diffusion rates observed by fluorescence correlation spectroscopy (FCS) and by direct imaging of fluorescently-labeled proteins. We first use the ESPResSo Molecular Dynamics code to estimate the surface transport distance for neutral and charged proteins. We then employ a Monte Carlo model to calculate the paths of protein molecules on surfaces and in the bulk liquid transport medium. Our results show that the transport characteristics depend strongly on the degree of molecular surface coverage.more »Atomic force microscope characterization of surfaces exposed to WGA proteins for 1000 s show large protein aggregates consistent with the predicted coverage. These calculations and experiments provide useful insight into the details of molecular motion in confined geometries.« less
Calculating alpha Eigenvalues in a Continuous-Energy Infinite Medium with Monte Carlo
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
2012-09-04T23:59:59.000Z
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.
Pérez-Andújar, Angélica [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)] [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Zhang, Rui; Newhauser, Wayne [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences at Houston, 6767 Bertner Avenue, Houston, Texas 77030 (United States)] [Department of Radiation Physics, Unit 1202, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences at Houston, 6767 Bertner Avenue, Houston, Texas 77030 (United States)
2013-12-15T23:59:59.000Z
Purpose: Stray neutron radiation is of concern after radiation therapy, especially in children, because of the high risk it might carry for secondary cancers. Several previous studies predicted the stray neutron exposure from proton therapy, mostly using Monte Carlo simulations. Promising attempts to develop analytical models have also been reported, but these were limited to only a few proton beam energies. The purpose of this study was to develop an analytical model to predict leakage neutron equivalent dose from passively scattered proton beams in the 100-250-MeV interval.Methods: To develop and validate the analytical model, the authors used values of equivalent dose per therapeutic absorbed dose (H/D) predicted with Monte Carlo simulations. The authors also characterized the behavior of the mean neutron radiation-weighting factor, w{sub R}, as a function of depth in a water phantom and distance from the beam central axis.Results: The simulated and analytical predictions agreed well. On average, the percentage difference between the analytical model and the Monte Carlo simulations was 10% for the energies and positions studied. The authors found that w{sub R} was highest at the shallowest depth and decreased with depth until around 10 cm, where it started to increase slowly with depth. This was consistent among all energies.Conclusion: Simple analytical methods are promising alternatives to complex and slow Monte Carlo simulations to predict H/D values. The authors' results also provide improved understanding of the behavior of w{sub R} which strongly depends on depth, but is nearly independent of lateral distance from the beam central axis.
Perfetti, Christopher M [ORNL] [ORNL; Martin, William R [University of Michigan] [University of Michigan; Rearden, Bradley T [ORNL] [ORNL; Williams, Mark L [ORNL] [ORNL
2012-01-01T23:59:59.000Z
Three methods for calculating continuous-energy eigenvalue sensitivity coefficients were developed and implemented into the SHIFT Monte Carlo code within the Scale code package. The methods were used for several simple test problems and were evaluated in terms of speed, accuracy, efficiency, and memory requirements. A promising new method for calculating eigenvalue sensitivity coefficients, known as the CLUTCH method, was developed and produced accurate sensitivity coefficients with figures of merit that were several orders of magnitude larger than those from existing methods.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Ibrahim, Ahmad M.; Wilson, Paul P.H.; Sawan, Mohamed E.; Mosher, Scott W.; Peplow, Douglas E.; Wagner, John C.; Evans, Thomas M.; Grove, Robert E.
2015-06-30T23:59:59.000Z
The CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques dramatically increase the efficiency of neutronics modeling, but their use in the accurate design analysis of very large and geometrically complex nuclear systems has been limited by the large number of processors and memory requirements for their preliminary deterministic calculations and final Monte Carlo calculation. Three mesh adaptivity algorithms were developed to reduce the memory requirements of CADIS and FW-CADIS without sacrificing their efficiency improvement. 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 muchmore »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. Using these algorithms 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 and, additionally, increased the efficiency of the Monte Carlo simulation by a factor of at least 3.4. The three algorithms enabled this difficult calculation to be accurately solved using an FW-CADIS simulation on a regular computer cluster, eliminating the need for a world-class super computer.« less
Monte Carlo Studies of the CALICE AHCAL Tiles Gaps and Non-uniformities
Felix Sefkow; Angela Lucaci-Timoce
2010-06-18T23:59:59.000Z
The CALICE analog HCAL is a highly granular calorimeter, proposed for the International Linear Collider. It is based on scintillator tiles, read out by silicon photomultipliers (SiPMs). The effects of gaps between the calorimeter tiles, as well as the non-uniform response of the tiles, in view of the impact on the energy resolution, are studied in Monte Carlo events. It is shown that these type of effects do not have a significant influence on the measurement of hadron showers.
Application of diffusion Monte Carlo to materials dominated by van der Waals interactions
Benali, Anouar [Argonne National Laboratory (ANL); Shulenburger, Luke [Sandia National Laboratory (SNL); Romero, Nichols [Argonne National Laboratory (ANL); Kim, Jeongnim [ORNL; Von Lilienfeld, Anatole [University of Basel
2014-01-01T23:59:59.000Z
Van der Waals forces are notoriously difficult to account for from first principles. We perform extensive calculation to assess the usefulness and validity of diffusion quantum Monte Carlo when applied to van der Waals forces. We present results for noble gas solids and clusters - archetypical van der Waals dominated assemblies, as well as a relevant pi-pi stacking supramolecular complex: DNA + intercalating anti-cancer drug Ellipticine.
Equation of state of strongly coupled quark--gluon plasma -- Path integral Monte Carlo results
V. S. Filinov; M. Bonitz; Y. B. Ivanov; V. V. Skokov; P. R. Levashov; V. E. Fortov
2009-05-04T23:59:59.000Z
A strongly coupled plasma of quark and gluon quasiparticles at temperatures from $ 1.1 T_c$ to $3 T_c$ is studied by path integral Monte Carlo simulations. This method extends previous classical nonrelativistic simulations based on a color Coulomb interaction to the quantum regime. We present the equation of state and find good agreement with lattice results. Further, pair distribution functions and color correlation functions are computed indicating strong correlations and liquid-like behavior.
Maximum likelihood parameter estimation in time series models using sequential Monte Carlo
Yildirim, Sinan
2013-06-11T23:59:59.000Z
, respectively. This approach is useful to handle the case where the columns of Y are generated sequentially in time, such as in audio signal processing. Usually very large number of columns in Y leads to the necessity of online algorithms to learn the model... .6 (dashed lines). For illustrative purposes, every 1000th estimate is shown . . . . . . . . . . . . . . . . . . . . . . . 130 6.1 Histograms of Monte Carlo estimates of gradients of log p?,?,?? (Y ?,?,?) w.r.t. the parameters of the ?-stable distribution...
Wang, Huihui; Meng, Lin; Liu, Dagang; Liu, Laqun [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)] [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)
2013-12-15T23:59:59.000Z
A particle-in-cell/Monte Carlo code is developed to rescale the microwave breakdown theory which is put forward by Vyskrebentsev and Raizer. The results of simulations show that there is a distinct error in this theory when the high energy tail of electron energy distribution function increases. A rescaling factor is proposed to modify this theory, and the change rule of the rescaling factor is presented.
Imaginary time correlations and the phaseless auxiliary field quantum Monte Carlo
Motta, M.; Galli, D. E.; Vitali, E. [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy)] [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Moroni, S. [IOM-CNR DEMOCRITOS National Simulation Center and SISSA, via Bonomea 265, 34136 Trieste (Italy)] [IOM-CNR DEMOCRITOS National Simulation Center and SISSA, via Bonomea 265, 34136 Trieste (Italy)
2014-01-14T23:59:59.000Z
The phaseless Auxiliary Field Quantum Monte Carlo (AFQMC) method provides a well established approximation scheme for accurate calculations of ground state energies of many-fermions systems. Here we address the possibility of calculating imaginary time correlation functions with the phaseless AFQMC. We give a detailed description of the technique and test the quality of the results for static properties and imaginary time correlation functions against exact values for small systems.
The Metropolis Monte Carlo method with CUDA enabled Graphic Processing Units
Hall, Clifford [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States) [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); Ji, Weixiao [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States)] [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); Blaisten-Barojas, Estela, E-mail: blaisten@gmu.edu [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States) [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States)
2014-02-01T23:59:59.000Z
We present a CPU–GPU system for runtime acceleration of large molecular simulations using GPU computation and memory swaps. The memory architecture of the GPU can be used both as container for simulation data stored on the graphics card and as floating-point code target, providing an effective means for the manipulation of atomistic or molecular data on the GPU. To fully take advantage of this mechanism, efficient GPU realizations of algorithms used to perform atomistic and molecular simulations are essential. Our system implements a versatile molecular engine, including inter-molecule interactions and orientational variables for performing the Metropolis Monte Carlo (MMC) algorithm, which is one type of Markov chain Monte Carlo. By combining memory objects with floating-point code fragments we have implemented an MMC parallel engine that entirely avoids the communication time of molecular data at runtime. Our runtime acceleration system is a forerunner of a new class of CPU–GPU algorithms exploiting memory concepts combined with threading for avoiding bus bandwidth and communication. The testbed molecular system used here is a condensed phase system of oligopyrrole chains. A benchmark shows a size scaling speedup of 60 for systems with 210,000 pyrrole monomers. Our implementation can easily be combined with MPI to connect in parallel several CPU–GPU duets. -- Highlights: •We parallelize the Metropolis Monte Carlo (MMC) algorithm on one CPU—GPU duet. •The Adaptive Tempering Monte Carlo employs MMC and profits from this CPU—GPU implementation. •Our benchmark shows a size scaling-up speedup of 62 for systems with 225,000 particles. •The testbed involves a polymeric system of oligopyrroles in the condensed phase. •The CPU—GPU parallelization includes dipole—dipole and Mie—Jones classic potentials.
An analysis of 4-quark energies in SU(2) lattice Monte Carlo
Sadataka Furui; Bilal Masud
1998-09-12T23:59:59.000Z
Energies of four-quark systems with the tetrahedral geometry measured by the static quenched SU(2) lattice Monte Carlo method are analyzed by parametrizing the gluon overlap factor in the form exp(-[bs EA+{\\sqrt bs}FP]) where A and P are the area and the perimeter defined mainly by the positions of the four quarks, bs is the string constant in the 2-quark potentials and E, F are constants.
Monte Carlo Study of Patchy Nanostructures Self-Assembled from a Single Multiblock Chain
Jakub Krajniak; Michal Banaszak
2014-10-15T23:59:59.000Z
We present a lattice Monte Carlo simulation for a multiblock copolymer chain of length N=240 and microarchitecture $(10-10)_{12}$.The simulation was performed using the Monte Carlo method with the Metropolis algorithm. We measured average energy, heat capacity, the mean squared radius of gyration, and the histogram of cluster count distribution. Those quantities were investigated as a function of temperature and incompatibility between segments, quantified by parameter {\\omega}. We determined the temperature of the coil-globule transition and constructed the phase diagram exhibiting a variety of patchy nanostructures. The presented results yield a qualitative agreement with those of the off-lattice Monte Carlo method reported earlier, with a significant exception for small incompatibilities,{\\omega}, and low temperatures, where 3-cluster patchy nanostructures are observed in contrast to the 2-cluster structures observed for the off-lattice $(10-10)_{12}$ chain. We attribute this difference to a considerable stiffness of lattice chains in comparison to that of the off-lattice chains.
Dornheim, Tobias; Groth, Simon; Filinov, Alexey; Bonitz, Michael
2015-01-01T23:59:59.000Z
The uniform electron gas (UEG) at finite temperature is of high current interest due to its key relevance for many applications including dense plasmas and laser excited solids. In particular, density functional theory heavily relies on accurate thermodynamic data for the UEG. Until recently, the only existing first-principle results had been obtained for $N=33$ electrons with restricted path integral Monte Carlo (RPIMC), for low to moderate density, $r_s = \\overline{r}/a_B \\gtrsim 1$. This data has been complemented by Configuration path integral Monte Carlo (CPIMC) simulations for $r_s \\leq 1$ that substantially deviate from RPIMC towards smaller $r_s$ and low temperature. In this work, we present results from an independent third method---the recently developed permutation blocking path integral Monte Carlo (PB-PIMC) approach [T. Dornheim \\textit{et al.}, NJP \\textbf{17}, 073017 (2015)] which we extend to the UEG. Interestingly, PB-PIMC allows us to perform simulations over the entire density range down to...
Alhassan, Erwin; Duan, Junfeng; Gustavsson, Cecilia; Koning, Arjan; Pomp, Stephan; Rochman, Dimitri; Österlund, Michael
2013-01-01T23:59:59.000Z
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.
Erwin Alhassan; Henrik Sjöstrand; Junfeng Duan; Cecilia Gustavsson; Arjan Koning; Stephan Pomp; Dimitri Rochman; Michael Österlund
2013-04-04T23:59:59.000Z
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.
Nonequilibrium candidate Monte Carlo: A new tool for efficient equilibrium simulation
Nilmeier, Jerome P.; Crooks, Gavin E.; Minh, David D. L.; Chodera, John D.
2011-11-08T23:59:59.000Z
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.
Kurebayashi, Shinya, 1976-
2004-01-01T23:59:59.000Z
Measurements from three classes of direct-drive implosions at the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] were combined with Monte-Carlo simulations to investigate models for determining ...
Stanley, H. Eugene
Liquid-Liquid Phase Transition in Confined Water: A Monte Carlo Study Martin Meyer and H. Eugene Stanley* Center for Polymer Studies and Department of Physics, Boston UniVersity, Boston, Massachusetts
Majumdar, Amit
there is interest to simulate enormously large Monte Carlo particle transport problems for neutron and photon.e., the end of a time step. Besides absorption, the photons may undergo Thompson scattering. The overall
Erickson, Lori
1995-01-01T23:59:59.000Z
Monte Carlo modeling techniques using mean information fields (MIF), developed by Torsten Hagerstrand in the 1950s, were integrated with a geographic information system (GIS) to simulate lost person behavior in wilderness areas. Big Bend Ranch State...
Tutt, Teresa Elizabeth
2009-05-15T23:59:59.000Z
Monte Carlo method is an invaluable tool in the field of radiation protection, used to calculate shielding effectiveness, as well as dose for medical applications. With few exceptions, most of the objects currently simulated have been homogeneous...
Li Li [Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, Xiamen (China); Xie Xixian [Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, Xiamen (China); Yang Feng [Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, Xiamen (China)]. E-mail: mbiotech@public.xm.fj.cn
2005-09-15T23:59:59.000Z
Based on a combination of SDS-PAGE and mass spectrometry, a protein with an apparent molecular mass of 31 kDa (termed as VP31) was identified from purified shrimp white spot syndrome virus (WSSV) envelope fraction. The resulting amino acid (aa) sequence matched an open reading frame (WSV340) of the WSSV genome. This ORF contained 783 nucleotides (nt), encoding 261 aa. A fragment of WSV340 was expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein with a 6His-tag, and then specific antibody was raised. Western blot analysis and the immunoelectron microscope method (IEM) confirmed that VP31 was present exclusively in the viral envelope fraction. The neutralization experiment suggested that VP31 might play an important role in WSSV infectivity.
A Monte-Carlo Method without Grid to Compute the Exchange Coefficient in the Double Porosity Model
Boyer, Edmond
Classification: 76S05 (65C05 76M35) Published in Monte Carlo Methods Appl.. 8:2, 129147, 2002 Archives, links Methods and Applications 8, 2 (2002) 129-147" #12;F. Campillo and A. Lejay / A Monte Carlo Method witouth consists in transforming (1) into a system: m Pm t = a-Pm - (Pm - Pf), m = Meas(m) Meas() f Pf t = a
A Positive-Weight Next-to-Leading-Order Monte Carlo for e+e- Annihilation to Hadrons
Oluseyi Latunde-Dada; Stefan Gieseke; Bryan Webber
2007-02-20T23:59:59.000Z
We apply the positive-weight Monte Carlo method of Nason for simulating QCD processes accurate to Next-To-Leading Order to the case of e+e- annihilation to hadrons. The method entails the generation of the hardest gluon emission first and then subsequently adding a `truncated' shower before the emission. We have interfaced our result to the Herwig++ shower Monte Carlo program and obtained better results than those obtained with Herwig++ at leading order with a matrix element correction.
Radiation doses in cone-beam breast computed tomography: A Monte Carlo simulation study
Yi Ying; Lai, Chao-Jen; Han Tao; Zhong Yuncheng; Shen Youtao; Liu Xinming; Ge Shuaiping; You Zhicheng; Wang Tianpeng; Shaw, Chris C. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)
2011-02-15T23:59:59.000Z
Purpose: In this article, we describe a method to estimate the spatial dose variation, average dose and mean glandular dose (MGD) for a real breast using Monte Carlo simulation based on cone beam breast computed tomography (CBBCT) images. We present and discuss the dose estimation results for 19 mastectomy breast specimens, 4 homogeneous breast models, 6 ellipsoidal phantoms, and 6 cylindrical phantoms. Methods: To validate the Monte Carlo method for dose estimation in CBBCT, we compared the Monte Carlo dose estimates with the thermoluminescent dosimeter measurements at various radial positions in two polycarbonate cylinders (11- and 15-cm in diameter). Cone-beam computed tomography (CBCT) images of 19 mastectomy breast specimens, obtained with a bench-top experimental scanner, were segmented and used to construct 19 structured breast models. Monte Carlo simulation of CBBCT with these models was performed and used to estimate the point doses, average doses, and mean glandular doses for unit open air exposure at the iso-center. Mass based glandularity values were computed and used to investigate their effects on the average doses as well as the mean glandular doses. Average doses for 4 homogeneous breast models were estimated and compared to those of the corresponding structured breast models to investigate the effect of tissue structures. Average doses for ellipsoidal and cylindrical digital phantoms of identical diameter and height were also estimated for various glandularity values and compared with those for the structured breast models. Results: The absorbed dose maps for structured breast models show that doses in the glandular tissue were higher than those in the nearby adipose tissue. Estimated average doses for the homogeneous breast models were almost identical to those for the structured breast models (p=1). Normalized average doses estimated for the ellipsoidal phantoms were similar to those for the structured breast models (root mean square (rms) percentage difference=1.7%; p=0.01), whereas those for the cylindrical phantoms were significantly lower (rms percentage difference=7.7%; p<0.01). Normalized MGDs were found to decrease with increasing glandularity. Conclusions: Our results indicate that it is sufficient to use homogeneous breast models derived from CBCT generated structured breast models to estimate the average dose. This investigation also shows that ellipsoidal digital phantoms of similar dimensions (diameter and height) and glandularity to actual breasts may be used to represent a real breast to estimate the average breast dose with Monte Carlo simulation. We have also successfully demonstrated the use of structured breast models to estimate the true MGDs and shown that the normalized MGDs decreased with the glandularity as previously reported by other researchers for CBBCT or mammography.
Barrera, C A; Moran, M J
2007-08-21T23:59:59.000Z
The Neutron Imaging System (NIS) is one of seven ignition target diagnostics under development for the National Ignition Facility. The NIS is required to record hot-spot (13-15 MeV) and downscattered (6-10 MeV) images with a resolution of 10 microns and a signal-to-noise ratio (SNR) of 10 at the 20% contour. The NIS is a valuable diagnostic since the downscattered neutrons reveal the spatial distribution of the cold fuel during an ignition attempt, providing important information in the case of a failed implosion. The present study explores the parameter space of several line-of-sight (LOS) configurations that could serve as the basis for the final design. Six commercially available organic scintillators were experimentally characterized for their light emission decay profile and neutron sensitivity. The samples showed a long lived decay component that makes direct recording of a downscattered image impossible. The two best candidates for the NIS detector material are: EJ232 (BC422) plastic fibers or capillaries filled with EJ399B. A Monte Carlo-based end-to-end model of the NIS was developed to study the imaging capabilities of several LOS configurations and verify that the recovered sources meet the design requirements. The model includes accurate neutron source distributions, aperture geometries (square pinhole, triangular wedge, mini-penumbral, annular and penumbral), their point spread functions, and a pixelated scintillator detector. The modeling results show that a useful downscattered image can be obtained by recording the primary peak and the downscattered images, and then subtracting a decayed version of the former from the latter. The difference images need to be deconvolved in order to obtain accurate source distributions. The images are processed using a frequency-space modified-regularization algorithm and low-pass filtering. The resolution and SNR of these sources are quantified by using two surrogate sources. The simulations show that all LOS configurations have a resolution of 7 microns or better. The 28 m LOS with a 7 x 7 array of 100-micron mini-penumbral apertures or 50-micron square pinholes meets the design requirements and is a very good design alternative.
Meyer, Jeff, E-mail: jmeye3@utsouthwestern.ed [University of Texas-M.D. Anderson Cancer Center, Houston, TX (United States); Bluett, Jaques; Amos, Richard [University of Texas-M.D. Anderson Cancer Center, Houston, TX (United States)
2010-10-01T23:59:59.000Z
Purpose: Conventional proton therapy with passively scattered beams is used to treat a number of tumor sites, including prostate cancer. Spot scanning proton therapy is a treatment delivery means that improves conformal coverage of the clinical target volume (CTV). Placement of individual spots within a target is dependent on traversed tissue density. Errors in patient alignment perturb dose distributions. Moreover, there is a need for a rational planning approach that can mitigate the dosimetric effect of random alignment errors. We propose a treatment planning approach and then analyze the consequences of various simulated alignment errors on prostate treatments. Methods and Materials: Ten control patients with localized prostate cancer underwent treatment planning for spot scanning proton therapy. After delineation of the clinical target volume, a scanning target volume (STV) was created to guide dose coverage. Errors in patient alignment in two axes (rotational and yaw) as well as translational errors in the anteroposterior direction were then simulated, and dose to the CTV and normal tissues were reanalyzed. Results: Coverage of the CTV remained high even in the setting of extreme rotational and yaw misalignments. Changes in the rectum and bladder V45 and V70 were similarly minimal, except in the case of translational errors, where, as a result of opposed lateral beam arrangements, much larger dosimetric perturbations were observed. Conclusions: The concept of the STV as applied to spot scanning radiation therapy and as presented in this report leads to robust coverage of the CTV even in the setting of extreme patient misalignments.
Fayer, Michael D.
J. Phys. Chem. 1993,97, 1901-1913 1901 Chemical Reaction Initiation and Hot-Spot Formation of chemical reactions has been the general lack of fundamental understanding of molecular level mechanical University,Stanford, California 94305 Daoa D.Dlott School of Chemical Sciences, University of Illinois
Tesfatsion, Leigh
electricity market. Once key variables such as water storage are accounted for, we show that our model can Spot Prices in Electricity Markets? Evidence from the New Zealand Electricity Market David Young1 , Stephen Poletti2 , Oliver Browne2 24th January 2012 Abstract Modelling price formation in electricity
Vernon, Zachary Isaac
2009-05-15T23:59:59.000Z
decisions affecting these disappearing systems. SPOT-5 imagery from 2005 was combined with Light Detection and Ranging (LiDAR) data from 2006 and several ancillary datasets to map a portion of the bottomland hardwood system found in the Sulphur River Basin...
Paris-Sud XI, Université de
the fourth International Polar Year (2007-2009) Jérôme Korona1 , Etienne Berthier*2,3 , Marc Bernard1. SPIRIT. SPOT 5 stereoscopic survey of Polar Ice: Reference Images and Topographies during the fourth International Polar Year (2007-2009). ISPRS J Photogramm, 64, 204-212, doi:10.1016/j.isprsjprs.2008.10.005, 2009
Charged-Particle Thermonuclear Reaction Rates: I. Monte Carlo Method and Statistical Distributions
Richard Longland; Christian Iliadis; Art Champagne; Joe Newton; Claudio Ugalde; Alain Coc; Ryan Fitzgerald
2010-04-23T23:59:59.000Z
A method based on Monte Carlo techniques is presented for evaluating thermonuclear reaction rates. We begin by reviewing commonly applied procedures and point out that reaction rates that have been reported up to now in the literature have no rigorous statistical meaning. Subsequently, we associate each nuclear physics quantity entering in the calculation of reaction rates with a specific probability density function, including Gaussian, lognormal and chi-squared distributions. Based on these probability density functions the total reaction rate is randomly sampled many times until the required statistical precision is achieved. This procedure results in a median (Monte Carlo) rate which agrees under certain conditions with the commonly reported recommended "classical" rate. In addition, we present at each temperature a low rate and a high rate, corresponding to the 0.16 and 0.84 quantiles of the cumulative reaction rate distribution. These quantities are in general different from the statistically meaningless "minimum" (or "lower limit") and "maximum" (or "upper limit") reaction rates which are commonly reported. Furthermore, we approximate the output reaction rate probability density function by a lognormal distribution and present, at each temperature, the lognormal parameters miu and sigma. The values of these quantities will be crucial for future Monte Carlo nucleosynthesis studies. Our new reaction rates, appropriate for bare nuclei in the laboratory, are tabulated in the second paper of this series (Paper II). The nuclear physics input used to derive our reaction rates is presented in the third paper of this series (Paper III). In the fourth paper of this series (Paper IV) we compare our new reaction rates to previous results.
Doebling, S.W.; Farrar, C.R. [Los Alamos National Lab., NM (United States); Cornwell, P.J. [Rose Hulman Inst. of Tech., Terre Haute, IN (United States)
1998-02-01T23:59:59.000Z
This paper presents a comparison of two techniques used to estimate the statistical confidence intervals on modal parameters identified from measured vibration data. The first technique is Monte Carlo simulation, which involves the repeated simulation of random data sets based on the statistics of the measured data and an assumed distribution of the variability in the measured data. A standard modal identification procedure is repeatedly applied to the randomly perturbed data sets to form a statistical distribution on the identified modal parameters. The second technique is the Bootstrap approach, where individual Frequency Response Function (FRF) measurements are randomly selected with replacement to form an ensemble average. This procedure, in effect, randomly weights the various FRF measurements. These weighted averages of the FRFs are then put through the modal identification procedure. The modal parameters identified from each randomly weighted data set are then used to define a statistical distribution for these parameters. The basic difference in the two techniques is that the Monte Carlo technique requires the assumption on the form of the distribution of the variability in the measured data, while the bootstrap technique does not. Also, the Monte Carlo technique can only estimate random errors, while the bootstrap statistics represent both random and bias (systematic) variability such as that arising from changing environmental conditions. However, the bootstrap technique requires that every frequency response function be saved for each average during the data acquisition process. Neither method can account for bias introduced during the estimation of the FRFs. This study has been motivated by a program to develop vibration-based damage identification procedures.
Monte-Carlo Simulation of Exclusive Channels in e+e- Annihilation at Low Energy
D. Anipko; S. Eidelman; A. Pak
2003-12-25T23:59:59.000Z
Software package for Monte-Carlo simulation of e+e- exclusive annihilation channels written in the C++ language for Linux/Solaris platforms has been developed. It incorporates matrix elements for several mechanisms of multipion production in a model of consequent two and three-body resonance decays. Possible charge states of intermediate and final particles are accounted automatically under the assumption of isospin conservation. Interference effects can be taken into acccount. Package structure allows adding new matrix elements written in a gauge-invariant form.
A Hybrid (Monte-Carlo/Deterministic) Approach for Multi-Dimensional Radiation Transport
Guillaume Bal; Anthony Davis; Ian Langmore
2011-05-07T23:59:59.000Z
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.
A Hybrid (Monte-Carlo/Deterministic) Approach for Multi-Dimensional Radiation Transport
Bal, Guillaume; Langmore, Ian
2011-01-01T23:59:59.000Z
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.
Kinetic lattice Monte Carlo simulations of interdiffusion in strained silicon germanium alloys
Chen, Renyu; Dunham, Scott T.
2010-03-03T23:59:59.000Z
Point-defect-mediated diffusion processes are investigated in strained SiGe alloys using kinetic lattice Monte Carlo *KLMC* simulation technique. The KLMC simulator incorporates an augmented lattice domain and includes defect structures, atomistic hopping mechanisms, and the stress dependence of transition rates obtained from density functional theory calculation results. Vacancy-mediated interdiffusion in strained SiGe alloys is analyzed, and the stress effect caused by the induced strain of germanium is quantified separately from that due to germanium-vacancy binding. The results indicate that both effects have substantial impact on interdiffusion. © 2010 American Vacuum Society.
Thermonuclear reaction rate of $^{18}$Ne($?$,$p$)$^{21}$Na from Monte-Carlo calculations
P. Mohr; R. Longland; C. Iliadis
2014-12-14T23:59:59.000Z
The $^{18}$Ne($\\alpha$,$p$)$^{21}$Na reaction impacts the break-out from the hot CNO-cycles to the $rp$-process in type I X-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte-Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.
Thermonuclear reaction rate of $^{18}$Ne($\\alpha$,$p$)$^{21}$Na from Monte-Carlo calculations
Mohr, P; Iliadis, C
2014-01-01T23:59:59.000Z
The $^{18}$Ne($\\alpha$,$p$)$^{21}$Na reaction impacts the break-out from the hot CNO-cycles to the $rp$-process in type I X-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte-Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.
A Monte Carlo study of the distribution of parameter estimators in a dual exponential decay model
Garcia, Raul
1969-01-01T23:59:59.000Z
of an estimate of the reliability of the parameter estimates calculated. In 1965, Bell and Garcia [2] developed a computer program which permits a solution of the parameters without the time-consuming effort of manual calcu- lations. The same year, Rossing [3...A MONTE CARLO STUDY OF THE DISTRIBUTION OF PARAMETER ESTIMATORS IN A DUAL EXPONENTIAL DECAY MODEL A Thesis by SAUL GARCIA Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree...
Monte Carlo calculations of the physical properties of RDX, {beta}-HMX, and TATB
Sewell, T.D.
1997-09-01T23:59:59.000Z
Atomistic Monte Carlo simulations in the NpT ensemble are used to calculate the physical properties of crystalline RDX, {beta}-HMX, and TATB. Among the issues being considered are the effects of various treatments of the intermolecular potential, inclusion of intramolecular flexibility, and simulation size dependence of the results. Calculations of the density, lattice energy, and lattice parameters are made over a wide range of pressures; thereby allowing for predictions of the bulk and linear coefficients of isothermal expansion of the crystals. Comparison with experiment is made where possible.
S. Frixione; E. Laenen; P. Motylinski; B. R. Webber
2007-02-20T23:59:59.000Z
We explain how angular correlations in leptonic decays of vector bosons and top quarks can be included in Monte Carlo parton showers, in particular those matched to NLO QCD computations. We consider the production of $n$ pairs of leptons, originating from the decays of $n$ electroweak vector bosons or of $n$ top quarks, in the narrow-width approximation. In the latter case, the information on the $n$ $b$ quarks emerging from the decays is also retained. We give results of implementing this procedure in MC@NLO
Perera, Meewanage Dilina N [ORNL; Li, Ying Wai [ORNL; Eisenbach, Markus [ORNL; Vogel, Thomas [Los Alamos National Laboratory (LANL); Landau, David P [University of Georgia, Athens, GA
2015-01-01T23:59:59.000Z
We describe the study of thermodynamics of materials using replica-exchange Wang Landau (REWL) sampling, a generic framework for massively parallel implementations of the Wang Landau Monte Carlo method. To evaluate the performance and scalability of the method, we investigate the magnetic phase transition in body-centered cubic (bcc) iron using the classical Heisenberg model parameterized with first principles calculations. We demonstrate that our framework leads to a significant speedup without compromising the accuracy and precision and facilitates the study of much larger systems than is possible with its serial counterpart.
Monte Carlo Generators for Studies of the 3D Structure of the Nucleon
Avagyan, Harut A. [JLAB
2015-01-01T23:59:59.000Z
Extraction of transverse momentum and space distributions of partons from measurements of spin and azimuthal asymmetries requires development of a self consistent analysis framework, accounting for evolution effects, and allowing control of systematic uncertainties due to variations of input parameters and models. Development of realistic Monte-Carlo generators, accounting for TMD evolution effects, spin-orbit and quark-gluon correlations will be crucial for future studies of quark-gluon dynamics in general and 3D structure of the nucleon in particular.
Monte-Carlo study of the phase transition in the AA-stacked bilayer graphene
A. A. Nikolaev; M. V. Ulybyshev
2014-12-04T23:59:59.000Z
Tight-binding model of the AA-stacked bilayer graphene with screened electron-electron interactions has been studied using the Hybrid Monte Carlo simulations on the original double-layer hexagonal lattice. Instantaneous screened Coulomb potential is taken into account using Hubbard-Stratonovich transformation. G-type antiferromagnetic ordering has been studied and the phase transition with spontaneous generation of the mass gap has been observed. Dependence of the antiferromagnetic condensate on the on-site electron-electron interaction is examined.
Temperature-extrapolation method for Implicit Monte Carlo - Radiation hydrodynamics calculations
McClarren, R. G. [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77802 (United States); Urbatsch, T. J. [XTD-5: Air Force Systems, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 77845 (United States)
2013-07-01T23:59:59.000Z
We present a method for implementing temperature extrapolation in Implicit Monte Carlo solutions to radiation hydrodynamics problems. The method is based on a BDF-2 type integration to estimate a change in material temperature over a time step. We present results for radiation only problems in an infinite medium and for a 2-D Cartesian hohlraum problem. Additionally, radiation hydrodynamics simulations are presented for an RZ hohlraum problem and a related 3D problem. Our results indicate that improvements in noise and general behavior are possible. We present considerations for future investigations and implementations. (authors)
The Imprints of IMBHs on the Structure of Globular Clusters: Monte-Carlo Simulations
Stefan Umbreit; John M. Fregeau; Frederic A. Rasio
2008-03-06T23:59:59.000Z
We present the first results of a series of Monte-Carlo simulations investigating the imprint of a central black hole on the core structure of a globular cluster. We investigate the three-dimensional and the projected density profile of the inner regions of idealized as well as more realistic globular cluster models, taking into account a stellar mass spectrum, stellar evolution and allowing for a larger, more realistic, number of stars than was previously possible with direct N-body methods. We compare our results to other N-body simulations published previously in the literature.
Alan M. Watson; William J. Henney
2001-08-30T23:59:59.000Z
We describe an efficient Monte Carlo algorithm for a restricted class of scattering problems in radiation transfer. This class includes many astrophysically interesting problems, including the scattering of ultraviolet and visible light by grains. The algorithm correctly accounts for multiply-scattered light. We describe the algorithm, present a number of important optimizations, and explicity show how the algorithm can be used to estimate quantities such as the emergent and mean intensity. We present two test cases, examine the importance of the optimizations, and show that this algorithm can be usefully applied to optically-thin problems, a regime sometimes considered limited to explicit single-scattering plus attenuation approximations.
Four-Quark Binding Energies from SU(2) Lattice Monte Carlo
A. M. Green; C. Michael; M. E. Sainio
1994-04-11T23:59:59.000Z
Energies of four-quark systems have been extracted in a static quenched SU(2) lattice Monte Carlo calculation for six different geometries, both planar and non-planar, with $\\beta=2.4$ and lattice size $16^3\\times 32$. In all cases, it is found that the binding energy is greatly enhanced when the four quarks can be partitioned in two ways with comparable energies. Also it is shown that the energies of the four-quark states cannot be understood simply in terms of two-quark potentials.
A new approach to hot particle dosimetry using a Monte Carlo transport code
Busche, Donna Marie
1989-01-01T23:59:59.000Z
Ci-hrs. This value assumes a threshold dose of 2000 rads to an area of 0. 1 cm&, at a depth of 100 ltm (NCRP 1988). The purpose of this research was evaluate the current methods used in industry to assess the doses from hot particles. A Monte Carlo electron... radioactivity being released from the site. Frisking, portal monitors, and step off pads are important HP areas and should involve overview and supervision. IDENTMCATION To properly assess the dose from these hot particles, the source strength, type...
Goncharov, V. N.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Follett, R. K.; Forrest, C. J.; Froula, D. H.; Glebov, V. Yu.; Harding, D. R.; Henchen, R. J.; Hu, S. X.; Igumenshchev, I. V.; Janezic, R.; Kelly, J. H. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others
2014-05-15T23:59:59.000Z
Reaching ignition in direct-drive (DD) inertial confinement fusion implosions requires achieving central pressures in excess of 100 Gbar. The OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] is used to study the physics of implosions that are hydrodynamically equivalent to the ignition designs on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)]. It is shown that the highest hot-spot pressures (up to 40 Gbar) are achieved in target designs with a fuel adiabat of ? ? 4, an implosion velocity of 3.8?×?10{sup 7}?cm/s, and a laser intensity of ?10{sup 15}?W/cm{sup 2}. These moderate-adiabat implosions are well understood using two-dimensional hydrocode simulations. The performance of lower-adiabat implosions is significantly degraded relative to code predictions, a common feature between DD implosions on OMEGA and indirect-drive cryogenic implosions on the NIF. Simplified theoretical models are developed to gain physical understanding of the implosion dynamics that dictate the target performance. These models indicate that degradations in the shell density and integrity (caused by hydrodynamic instabilities during the target acceleration) coupled with hydrodynamics at stagnation are the main failure mechanisms in low-adiabat designs. To demonstrate ignition hydrodynamic equivalence in cryogenic implosions on OMEGA, the target-design robustness to hydrodynamic instability growth must be improved by reducing laser-coupling losses caused by cross beam energy transfer.
Faisal, M.; Marzouk, M.S.; Smith, C.L.; Huggett, R.J. (Virginia Institute of Marine Science, School of Marine Science, College of William Mary, Gloucester Point (United States))
1991-01-01T23:59:59.000Z
The marine fish spot, Leiostomus xanthurus, was collected from five sites in the lower Chesapeake Bay system representing a gradient of sediment polycyclic aromatic hydrocarbon (PAH) concentrations. The proliferative responses to mitogens by anterior kidney lymphocytes were assessed using (3H)-thymidine uptake by replicating DNA. The data show two different mitogen-dependent lymphocytic responses as the sediment PAH levels increase at the sampling sites; a suppression of the response to the T cell mitogens, concanavalin A (Con A) and phytohemagglutinin, and a sharp augmentation of the response to B cell mitogen, lipopolysaccharide (LPS), as well as to poke weed mitogen and peanut agglutinin. The magnitude of the lymphoproliferative responses correlated strongly with the total sediment PAH concentrations (r2 greater than 0.8). A similar correlation was also observed with 15 selected individual PAH compounds regardless of their molecular weights. By maintaining the fish in clean York River water for up to 24 weeks, it was possible to reverse the augmented proliferative responses to LPS of fish from all sampling sites and to increase the reduced responses to Con A, in fish from three sites, and partially in two sites where sediments were highly contaminated with PAH. These results suggest that the proliferative responses of fish lymphocytes to mitogens may be a potentially sensitive biomarker of exposure to, and effects of xenobiotics.
Use of SCALE Continuous-Energy Monte Carlo Tools for Eigenvalue Sensitivity Coefficient Calculations
Perfetti, Christopher M [ORNL] [ORNL; Rearden, Bradley T [ORNL] [ORNL
2013-01-01T23:59:59.000Z
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.
Using Monte Carlo analyses in uptake models for evaluating risks to ecological receptors
Hayse, J.W.; Hlohowskyj, I. [Argonne National Lab., IL (United States). Environmental Assessment Div.
1995-12-31T23:59:59.000Z
A deterministic modeling approach was used to evaluate risks to wildlife receptors at a contaminated site in Maryland. Models to predict daily doses of contaminants to ecological receptors used single point estimates for media contaminant concentrations and for ecological exposure factors. Predicted doses exceeding contaminant- and species-specific dose values were considered to be indicative of adverse risk, and the model results are being used to develop and evaluate remedial alternatives for the site. Risk estimates based on the deterministic approach predicted daily contaminant doses exceeding acceptable dose levels for more than half of the modeled receptors. Ecological risks were also evaluated using a stochastic approach. In this approach the input parameters that most greatly affected the deterministic model outcome were identified using sensitivity analyses. Statistical distributions were assigned to these parameters, and Monte Carlo simulations of the models were conducted to generate probability density functions of contaminant doses. The resulting probability density functions were then used to quantify the probability that contaminant uptake would exceed the acceptable dose values. Models using Monte Carlo analyses identified only a low probability of exceeding the acceptable dose level for most of the contaminants and receptors. The differences in the risks predicted using the deterministic and stochastic models would likely result in the selection of different remediation goals and actions for the same area of contamination. Given the different interpretations that could result from these two modeling approaches, the authors recommend that both techniques be considered for estimating risks to ecological receptors.
An Evaluation of Monte Carlo Simulations of Neutron Multiplicity Measurements of Plutonium Metal
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
2012-06-21T23:59:59.000Z
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.
Massively parallel Monte Carlo for many-particle simulations on GPUs
Anderson, Joshua A.; Jankowski, Eric [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Grubb, Thomas L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Engel, Michael [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Glotzer, Sharon C., E-mail: sglotzer@umich.edu [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)
2013-12-01T23:59:59.000Z
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.
SIMDET - Version 4 A Parametric Monte Carlo for a TESLA Detector
M. Pohl; H. J. Schreiber
2002-06-05T23:59:59.000Z
A new release of the parametric detector Monte Carlo program \\verb+SIMDET+ (version 4.01) is now available. We describe the principles of operation and the usage of this program to simulate the response of a detector for the TESLA linear collider. The detector components are implemented according to the TESLA Technical Design Report. All detector component responses are treated in a realistic way using a parametrisation of results from the {\\em ab initio} Monte Carlo program \\verb+BRAHMS+. Pattern recognition is emulated using a complete cross reference between generated particles and detector response. Also, for charged particles, the covariance matrix and $dE/dx$ information are made available. An idealised energy flow algorithm defines the output of the program, consisting of particles generically classified as electrons, photons, muons, charged and neutral hadrons as well as unresolved clusters. The program parameters adjustable by the user are described in detail. User hooks inside the program and the output data structure are documented.
A Monte Carlo Study of Multiplicity Fluctuations in Pb-Pb Collisions at LHC Energies
Ramni Gupta
2015-01-15T23:59:59.000Z
With large volumes of data available from LHC, it has become possible to study the multiplicity distributions for the various possible behaviours of the multiparticle production in collisions of relativistic heavy ion collisions, where a system of dense and hot partons has been created. In this context it is important and interesting as well to check how well the Monte Carlo generators can describe the properties or the behaviour of multiparticle production processes. One such possible behaviour is the self-similarity in the particle production, which can be studied with the intermittency studies and further with chaoticity/erraticity, in the heavy ion collisions. We analyse the behaviour of erraticity index in central Pb-Pb collisions at centre of mass energy of 2.76 TeV per nucleon using the AMPT monte carlo event generator, following the recent proposal by R.C. Hwa and C.B. Yang, concerning the local multiplicity fluctuation study as a signature of critical hadronization in heavy-ion collisions. We report the values of erraticity index for the two versions of the model with default settings and their dependence on the size of the phase space region. Results presented here may serve as a reference sample for the experimental data from heavy ion collisions at these energies.
Bias-Variance Techniques for Monte Carlo Optimization: Cross-validation for the CE Method
Rajnarayan, Dev
2008-01-01T23:59:59.000Z
In this paper, we examine the CE method in the broad context of Monte Carlo Optimization (MCO) and Parametric Learning (PL), a type of machine learning. A well-known overarching principle used to improve the performance of many PL algorithms is the bias-variance tradeoff. This tradeoff has been used to improve PL algorithms ranging from Monte Carlo estimation of integrals, to linear estimation, to general statistical estimation. Moreover, as described by, MCO is very closely related to PL. Owing to this similarity, the bias-variance tradeoff affects MCO performance, just as it does PL performance. In this article, we exploit the bias-variance tradeoff to enhance the performance of MCO algorithms. We use the technique of cross-validation, a technique based on the bias-variance tradeoff, to significantly improve the performance of the Cross Entropy (CE) method, which is an MCO algorithm. In previous work we have confirmed that other PL techniques improve the perfomance of other MCO algorithms. We conclude that ...
Physics and Algorithm Enhancements for a Validated MCNP/X Monte Carlo Simulation Tool, Phase VII
McKinney, Gregg W [Los Alamos National Laboratory
2012-07-17T23:59:59.000Z
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.
Quantum Monte Carlo algorithms for electronic structure at the petascale; the endstation project.
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; Srinivasan, A
2008-10-01T23:59:59.000Z
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.
Monte Carlo Simulations of Globular Cluster Evolution. IV. Direct Integration of Strong Interactions
John M. Fregeau; Frederic A. Rasio
2006-12-06T23:59:59.000Z
We study the dynamical evolution of globular clusters containing populations of primordial binaries, using our newly updated Monte Carlo cluster evolution code with the inclusion of direct integration of binary scattering interactions. We describe the modifications we have made to the code, as well as improvements we have made to the core Monte Carlo method. We present several test calculations to verify the validity of the new code, and perform many comparisons with previous analytical and numerical work in the literature. We simulate the evolution of a large grid of models, with a wide range of initial cluster profiles, and with binary fractions ranging from 0 to 1, and compare with observations of Galactic globular clusters. We find that our code yields very good agreement with direct N-body simulations of clusters with primordial binaries, but yields some results that differ significantly from other approximate methods. Notably, the direct integration of binary interactions reduces their energy generation rate relative to the simple recipes used in Paper III, and yields smaller core radii. Our results for the structural parameters of clusters during the binary-burning phase are now in the tail of the range of parameters for observed clusters, implying that either clusters are born significantly more or less centrally concentrated than has been previously considered, or that there are additional physical processes beyond two-body relaxation and binary interactions that affect the structural characteristics of clusters.
Monte Carlo uncertainty reliability and isotope production calculations for a fast reactor
Miles, T.L.
1992-01-01T23:59:59.000Z
Statistical uncertainties in Monte Carlo calculations are typically determined by the first and second moments of the tally. For certain types of calculations, there is concern that the uncertainty estimate is significantly non-conservative. This is typically seen in reactor eigenvalue problems where the uncertainty estimate is aggravated by the generation-to-generation fission source. It has been speculated that optimization of the random walk, through biasing techniques, may increase the non-conservative nature of the uncertainty estimate. A series of calculations are documented here which quantify the reliability of the Monte Carlo Neutron and Photon (MCNP) mean and uncertainty estimates by comparing these estimates to the true mean. These calculations were made with a liquid metal fast reactor model, but every effort was made to isolate the statistical nature of the uncertainty estimates so that the analysis of the reliability of the MCNP estimates should be relevant for small thermal reactors as well. Also, preliminary reactor physics calculations for two different special isotope production test assemblies for irradiation in the Fast Flux Test Facility (FFTF) were performed using MCNP and are documented here. The effect of an yttrium-hydride moderator to tailor the neutron flux incident on the targets to maximize isotope production for different designs in different locations within the reactor is discussed. These calculations also demonstrate the useful application of MCNP in design iterations by utilizing many of the codes features.
Camden, Jon P
2013-07-16T23:59:59.000Z
A major component of this proposal is to elucidate the connection between optical and electron excitation of plasmon modes in metallic nanostructures. These accomplishments are reported: developed a routine protocol for obtaining spatially resolved, low energy EELS spectra, and resonance Rayleigh scattering spectra from the same nanostructures.; correlated optical scattering spectra and plasmon maps obtained using STEM/EELS.; and imaged electromagnetic hot spots responsible for single-molecule surface-enhanced Raman scattering (SMSERS).
Yousef, Adel K. M. [Faculty of Engineering , University of Diyala, Diyala-Baqouba (Iraq); Taha, Ziad A.; Shehab, Abeer A. [Institute of laser for postgraduate studies, Baghdad University, Baghdad (Iraq)
2011-01-17T23:59:59.000Z
This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.
Nakano, Y., E-mail: nakano.yuuji@c.mbox.nagoya-u.ac.jp; Yamazaki, A.; Watanabe, K.; Uritani, A. [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Ogawa, K.; Isobe, M. [National Institute for Fusion Science, Toki-city, GIFU 509-5292 (Japan)
2014-11-15T23:59:59.000Z
Neutron monitoring is important to manage safety of fusion experiment facilities because neutrons are generated in fusion reactions. Monte Carlo simulations play an important role in evaluating the influence of neutron scattering from various structures and correcting differences between deuterium plasma experiments and in situ calibration experiments. We evaluated these influences based on differences between the both experiments at Large Helical Device using Monte Carlo simulation code MCNP5. A difference between the both experiments in absolute detection efficiency of the fission chamber between O-ports is estimated to be the biggest of all monitors. We additionally evaluated correction coefficients for some neutron monitors.
Experimental Study and Monte Carlo Modeling of Calcium Borosilicate Glasses Leaching
Arab, Mehdi; Cailleteau, Celine; Angeli, Frederic [CEA/DTCD/SECM/Laboratoire d'etudes du Comportement a Long Terme, CEA Centre Valrho, BP 17171, Bagnols-sur-ceze, 30207 (France); Devreux, Francois [Laboratoire de Physique de la Matiere Condensee, CNRS and Ecole Polytechnique, Palaiseau Cedex, 91128 (France)
2007-07-01T23:59:59.000Z
During aqueous alteration of glass an alteration layer appears on the glass surface. The properties of this alteration layer are of great importance for understanding and predicting the long-term behavior of high-level radioactive waste glasses. Numerical modeling can be very useful for understanding the impact of the glass composition on its aqueous reactivity and long-term properties but it is quite difficult to model these complex glasses. In order to identify the effect of the calcium content on glass alteration, seven oxide glass compositions (57SiO{sub 2} 17B{sub 2}O{sub 3} (22-x)Na{sub 2}O{sub x}CaO 4ZrO{sub 2}; 0 < x < 11) were investigated and a Monte Carlo model was developed to describe their leaching behavior. The specimens were altered at constant temperature (T = 90 deg. C) at a glass-surface-area-to-solution-volume (SA/V) ratio of 15 cm-1 in a buffered solution (pH 9.2). Under these conditions all the variations observed in the leaching behavior are attributable to composition effects. Increasing the calcium content in the glass appears to be responsible for a sharp drop in the final leached boron fraction. In parallel with this experimental work, a Monte Carlo model was developed to investigate the effect of calcium content on the leaching behavior especially on the initial stage of alteration. Monte Carlo simulations performed with this model are in good agreement with the experimental results. The dependence of the alteration rate on the calcium content can be described by a quadratic function: fitting the simulated points gives a minimum alteration rate at about 7.7 mol% calcium. This value is consistent with the figure of 8.2 mol% obtained from the experimental work. The model was also used to investigate the role of calcium in the glass structure and it pointed out that calcium act preferentially as a network modifier rather than a charge compensator in this kind of glasses. (authors)
Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel; Fisher, Ryan; Tien, Chris; Simon, Steven L.; Bouville, Andre; 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, Yongin 446-701 (Korea, Republic of); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States); Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States)
2011-03-15T23:59:59.000Z
Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.
Multi-Scale Multi-physics Methods Development for the Calculation of Hot-Spots in the NGNP
Downar, Thomas; Seker, Volkan
2013-04-30T23:59:59.000Z
Radioactive gaseous fission products are released out of the fuel element at a significantly higher rate when the fuel temperature exceeds 1600°C in high-temperature gas-cooled reactors (HTGRs). Therefore, it is of paramount importance to accurately predict the peak fuel temperature during all operational and design-basis accident conditions. The current methods used to predict the peak fuel temperature in HTGRs, such as the Next-Generation Nuclear Plant (NGNP), estimate the average fuel temperature in a computational mesh modeling hundreds of fuel pebbles or a fuel assembly in a pebble-bed reactor (PBR) or prismatic block type reactor (PMR), respectively. Experiments conducted in operating HTGRs indicate considerable uncertainty in the current methods and correlations used to predict actual temperatures. The objective of this project is to improve the accuracy in the prediction of local "hot" spots by developing multi-scale, multi- physics methods and implementing them within the framework of established codes used for NGNP analysis. The multi-scale approach which this project will implement begins with defining suitable scales for a physical and mathematical model and then deriving and applying the appropriate boundary conditions between scales. The macro scale is the greatest length that describes the entire reactor, whereas the meso scale models only a fuel block in a prismatic reactor and ten to hundreds of pebbles in a pebble bed reactor. The smallest scale is the micro scale--the level of a fuel kernel of the pebble in a PBR and fuel compact in a PMR--which needs to be resolved in order to calculate the peak temperature in a fuel kernel.
Le Roy, Robert J.
Path-integral Monte Carlo simulation of 3 vibrational shifts for CO2 in ,,He...n clusters critically tests the HeCO2 potential energy surface Hui Li,1 Nicholas Blinov,2,3 Pierre-Nicholas Roy,1 2009; accepted 20 February 2009; published online 9 April 2009 Path-integral Monte Carlo simulations
Richardson, David
Directions for in-gel tryptic digestions of coomassie-stained 1D Bands and 2D Spots. NOTE: Although digestion should be done in a BSC or laminar flow hood. 2. Wear nitrile (not latex) gloves. 3. Wear a lab (for a single 2D gel spot, use 25-30 µL of 10 ng/µL trypsin). 9. Digest overnight for 16-18 hours at 37
Richardson, David
Directions for in-gel tryptic digestions of coomassie-stained 1D Bands and 2D Spots. NOTE: Although digestion should be done in a BSC or laminar flow hood. 2. Wear nitrile (not latex) gloves. 3. Wear a lab gel spot, use 25-30 µL of 10 ng/µL trypsin). 5. Digest overnight for 16-18 hours at 37°C. 6. Following
Application analysis of Monte Carlo to estimate the capacity of geothermal resources in Lawu Mount
Supriyadi, E-mail: supriyadi-uno@yahoo.co.nz [Physics, Faculty of Mathematics and Natural Sciences, University of Jember, Jl. Kalimantan Kampus Bumi Tegal Boto, Jember 68181 (Indonesia); Srigutomo, Wahyu [Complex system and earth physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Munandar, Arif [Kelompok Program Penelitian Panas Bumi, PSDG, Badan Geologi, Kementrian ESDM, Jl. Soekarno Hatta No. 444 Bandung 40254 (Indonesia)
2014-03-24T23:59:59.000Z
Monte Carlo analysis has been applied in calculation of geothermal resource capacity based on volumetric method issued by Standar Nasional Indonesia (SNI). A deterministic formula is converted into a stochastic formula to take into account the nature of uncertainties in input parameters. The method yields a range of potential power probability stored beneath Lawu Mount geothermal area. For 10,000 iterations, the capacity of geothermal resources is in the range of 139.30-218.24 MWe with the most likely value is 177.77 MWe. The risk of resource capacity above 196.19 MWe is less than 10%. The power density of the prospect area covering 17 km{sup 2} is 9.41 MWe/km{sup 2} with probability 80%.
A new time quantifiable Monte Carlo method in simulating magnetization reversal process
X. Z. Cheng; M. B. A. Jalil; H. K. Lee; Y. Okabe
2005-04-14T23:59:59.000Z
We propose a new time quantifiable Monte Carlo (MC) method to simulate the thermally induced magnetization reversal for an isolated single domain particle system. The MC method involves the determination of density of states, and the use of Master equation for time evolution. We derive an analytical factor to convert MC steps into real time intervals. Unlike a previous time quantified MC method, our method is readily scalable to arbitrarily long time scales, and can be repeated for different temperatures with minimal computational effort. Based on the conversion factor, we are able to make a direct comparison between the results obtained from MC and Langevin dynamics methods, and find excellent agreement between them. An analytical formula for the magnetization reversal time is also derived, which agrees very well with both numerical Langevin and time-quantified MC results, over a large temperature range and for parallel and oblique easy axis orientations.
Monte Carlo study of Lefschetz thimble structure in one-dimensional Thirring model at finite density
Fujii, Hirotsugu; Kikukawa, Yoshio
2015-01-01T23:59:59.000Z
We consider the one-dimensional massive Thirring model formulated on the lattice with staggered fermions and an auxiliary compact vector (link) field, which is exactly solvable and shows a phase transition with increasing the chemical potential of fermion number: the crossover at a finite temperature and the first order transition at zero temperature. We complexify its path-integration on Lefschetz thimbles and examine its phase transition by hybrid Monte Carlo simulations on the single dominant thimble. We observe a discrepancy between the numerical and exact results in the crossover region for small inverse coupling $\\beta$ and/or large lattice size $L$, while they are in good agreement at the lower and higher density regions. We also observe that the discrepancy persists in the continuum limit keeping the temperature finite and it becomes more significant toward the low-temperature limit. This numerical result is consistent with our analytical study of the model's thimble structure. And these results imply...
I. B. Bischofs; U. S. Schwarz
2006-01-16T23:59:59.000Z
Compliant environments can mediate interactions between mechanically active cells like fibroblasts. Starting with a phenomenological model for the behaviour of single cells, we use extensive Monte Carlo simulations to predict non-trivial structure formation for cell communities on soft elastic substrates as a function of elastic moduli, cell density, noise and cell position geometry. In general, we find a disordered structure as well as ordered string-like and ring-like structures. The transition between ordered and disordered structures is controlled both by cell density and noise level, while the transition between string- and ring-like ordered structures is controlled by the Poisson ratio. Similar effects are observed in three dimensions. Our results suggest that in regard to elastic effects, healthy connective tissue usually is in a macroscopically disordered state, but can be switched to a macroscopically ordered state by appropriate parameter variations, in a way that is reminiscent of wound contraction or diseased states like contracture.
Mergers of galaxies in clusters: Monte Carlo simulation of mass and angular momentum distribution
D. S. Krivitsky; V. M. Kontorovich
1997-03-04T23:59:59.000Z
A Monte Carlo simulation of mergers in clusters of galaxies is carried out. An ``explosive'' character of the merging process (an analog of phase transition), suggested earlier by Cavaliere et al. (1991), Kontorovich et al. (1992), is confirmed. In particular, a giant object similar to cD-galaxy is formed in a comparatively short time as a result of mergers. Mass and angular momentum distribution function for galaxies is calculated. An intermediate asymptotics of the mass function is close to a power law with the exponent $\\alpha\\approx2$. It may correspond to recent observational data for steep faint end of the luminosity function. The angular momentum distribution formed by mergers is close to Gaussian, the rms dimensionless angular momentum $S/(GM^3R)^{1/2}$ being approximately independent of mass, which is in accordance with observational data.
Resonating Valence Bond Quantum Monte Carlo: Application to the ozone molecule
Sam Azadi; Ranber Singh; Thomas D. Kühne
2015-02-24T23:59:59.000Z
We study the potential energy surface of the ozone molecule by means of Quantum Monte Carlo simulations based on the resonating valence bond concept. The trial wave function consists of an antisymmetrized geminal power arranged in a single-determinant that is multiplied by a Jastrow correlation factor. Whereas the determinantal part incorporates static correlation effects, the augmented real-space correlation factor accounts for the dynamics electron correlation. The accuracy of this approach is demonstrated by computing the potential energy surface for the ozone molecule in three vibrational states: symmetric, asymmetric and scissoring. We find that the employed wave function provides a detailed description of rather strongly-correlated multi-reference systems, which is in quantitative agreement with experiment.
Validation of GEANT4 Monte Carlo Models with a Highly Granular Scintillator-Steel Hadron Calorimeter
C. Adloff; J. Blaha; J. -J. Blaising; C. Drancourt; A. Espargilière; R. Gaglione; N. Geffroy; Y. Karyotakis; J. Prast; G. Vouters; K. Francis; J. Repond; J. Schlereth; J. Smith; L. Xia; E. Baldolemar; J. Li; S. T. Park; M. Sosebee; A. P. White; J. Yu; T. Buanes; G. Eigen; Y. Mikami; N. K. Watson; G. Mavromanolakis; M. A. Thomson; D. R. Ward; W. Yan; D. Benchekroun; A. Hoummada; Y. Khoulaki; J. Apostolakis; A. Dotti; G. Folger; V. Ivantchenko; V. Uzhinskiy; M. Benyamna; C. Cârloganu; F. Fehr; P. Gay; S. Manen; L. Royer; G. C. Blazey; A. Dyshkant; J. G. R. Lima; V. Zutshi; J. -Y. Hostachy; L. Morin; U. Cornett; D. David; G. Falley; K. Gadow; P. Göttlicher; C. Günter; B. Hermberg; S. Karstensen; F. Krivan; A. -I. Lucaci-Timoce; S. Lu; B. Lutz; S. Morozov; V. Morgunov; M. Reinecke; F. Sefkow; P. Smirnov; M. Terwort; A. Vargas-Trevino; N. Feege; E. Garutti; I. Marchesinik; M. Ramilli; P. Eckert; T. Harion; A. Kaplan; H. -Ch. Schultz-Coulon; W. Shen; R. Stamen; B. Bilki; E. Norbeck; Y. Onel; G. W. Wilson; K. Kawagoe; P. D. Dauncey; A. -M. Magnan; V. Bartsch; M. Wing; F. Salvatore; E. Calvo Alamillo; M. -C. Fouz; J. Puerta-Pelayo; B. Bobchenko; M. Chadeeva; M. Danilov; A. Epifantsev; O. Markin; R. Mizuk; E. Novikov; V. Popov; V. Rusinov; E. Tarkovsky; N. Kirikova; V. Kozlov; P. Smirnov; Y. Soloviev; P. Buzhan; A. Ilyin; V. Kantserov; V. Kaplin; A. Karakash; E. Popova; V. Tikhomirov; C. Kiesling; K. Seidel; F. Simon; C. Soldner; M. Szalay; M. Tesar; L. Weuste; M. S. Amjad; J. Bonis; S. Callier; S. Conforti di Lorenzo; P. Cornebise; Ph. Doublet; F. Dulucq; J. Fleury; T. Frisson; N. van der Kolk; H. Li; G. Martin-Chassard; F. Richard; Ch. de la Taille; R. Pöschl; L. Raux; J. Rouëné; N. Seguin-Moreau; M. Anduze; V. Boudry; J-C. Brient; D. Jeans; P. Mora de Freitas; G. Musat; M. Reinhard; M. Ruan; H. Videau; B. Bulanek; J. Zacek; J. Cvach; P. Gallus; M. Havranek; M. Janata; J. Kvasnicka; D. Lednicky; M. Marcisovsky; I. Polak; J. Popule; L. Tomasek; M. Tomasek; P. Ruzicka; P. Sicho; J. Smolik; V. Vrba; J. Zalesak; B. Belhorma; H. Ghazlane; T. Takeshita; S. Uozumi; M. Götze; O. Hartbrich; J. Sauer; S. Weber; C. Zeitnitz
2014-06-15T23:59:59.000Z
Calorimeters with a high granularity are a fundamental requirement of the Particle Flow paradigm. This paper focuses on the prototype of a hadron calorimeter with analog readout, consisting of thirty-eight scintillator layers alternating with steel absorber planes. The scintillator plates are finely segmented into tiles individually read out via Silicon Photomultipliers. The presented results are based on data collected with pion beams in the energy range from 8GeV to 100GeV. The fine segmentation of the sensitive layers and the high sampling frequency allow for an excellent reconstruction of the spatial development of hadronic showers. A comparison between data and Monte Carlo simulations is presented, concerning both the longitudinal and lateral development of hadronic showers and the global response of the calorimeter. The performance of several GEANT4 physics lists with respect to these observables is evaluated.
Monte-Carlo study of quasiparticle dispersion relation in monolayer graphene
P. V. Buividovich
2013-01-07T23:59:59.000Z
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.
Hybrid Monte-Carlo simulation of interacting tight-binding model of graphene
Dominik Smith; Lorenz von Smekal
2013-11-05T23:59:59.000Z
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.
Introduction to Computational Physics and Monte Carlo Simulations of Matrix Field Theory
Ydri, Badis
2015-01-01T23:59:59.000Z
This book is divided into two parts. In the first part we give an elementary introduction to computational physics consisting of 21 simulations which originated from a formal course of lectures and laboratory simulations delivered since 2010 to physics students at Annaba University. The second part is much more advanced and deals with the problem of how to set up working Monte Carlo simulations of matrix field theories which involve finite dimensional matrix regularizations of noncommutative and fuzzy field theories, fuzzy spaces and matrix geometry. The study of matrix field theory in its own right has also become very important to the proper understanding of all noncommutative, fuzzy and matrix phenomena. The second part, which consists of 9 simulations, was delivered informally to doctoral students who are working on various problems in matrix field theory. Sample codes as well as sample key solutions are also provided for convenience and completness. An appendix containing an executive arabic summary of t...
Thomas, Robert E; Overy, Catherine; Knowles, Peter J; Alavi, Ali; Booth, George H
2015-01-01T23:59:59.000Z
Unbiased stochastic sampling of the one- and two-body reduced density matrices is achieved in full configuration interaction quantum Monte Carlo with the introduction of a second, "replica" ensemble of walkers, whose population evolves in imaginary time independently from the first, and which entails only modest additional computational overheads. The matrices obtained from this approach are shown to be representative of full configuration-interaction quality, and hence provide a realistic opportunity to achieve high-quality results for a range of properties whose operators do not necessarily commute with the hamiltonian. A density-matrix formulated quasi-variational energy estimator having been already proposed and investigated, the present work extends the scope of the theory to take in studies of analytic nuclear forces, molecular dipole moments and polarisabilities, with extensive comparison to exact results where possible. These new results confirm the suitability of the sampling technique and, where suf...
Monte Carlo and Renormalization Group Effective Potentials in Scalar Field Theories
J. R. Shepard; V. Dmitrašinovi?; J. A. McNeil
1994-12-29T23:59:59.000Z
We study constraint effective potentials for various strongly interacting $\\phi^4$ theories. Renormalization group (RG) equations for these quantities are discussed and a heuristic development of a commonly used RG approximation is presented which stresses the relationships among the loop expansion, the Schwinger-Dyson method and the renormalization group approach. We extend the standard RG treatment to account explicitly for finite lattice effects. Constraint effective potentials are then evaluated using Monte Carlo (MC) techniques and careful comparisons are made with RG calculations. Explicit treatment of finite lattice effects is found to be essential in achieving quantitative agreement with the MC effective potentials. Excellent agreement is demonstrated for $d=3$ and $d=4$, O(1) and O(2) cases in both symmetric and broken phases.
Ab-initio molecular dynamics simulation of liquid water by Quantum Monte Carlo
Andrea Zen; Ye Luo; Guglielmo Mazzola; Leonardo Guidoni; Sandro Sorella
2015-04-21T23:59:59.000Z
Although liquid water is ubiquitous in chemical reactions at roots of life and climate on the earth, the prediction of its properties by high-level ab initio molecular dynamics simulations still represents a formidable task for quantum chemistry. In this article we present a room temperature simulation of liquid water based on the potential energy surface obtained by a many-body wave function through quantum Monte Carlo (QMC) methods. The simulated properties are in good agreement with recent neutron scattering and X-ray experiments, particularly concerning the position of the oxygen-oxygen peak in the radial distribution function, at variance of previous Density Functional Theory attempts. Given the excellent performances of QMC on large scale supercomputers, this work opens new perspectives for predictive and reliable ab-initio simulations of complex chemical systems.
Update of the MCSANC Monte Carlo Integrator, v.1.20
A. Arbuzov; D. Bardin; S. Bondarenko; P. Christova; L. Kalinovskaya; U. Klein; V. Kolesnikov; R. Sadykov; A. Sapronov; F. Uskov
2015-09-10T23:59:59.000Z
This article presents new features of the MCSANC v.1.20 program, a Monte Carlo tool for calculation of the next-to-leading order electroweak and QCD corrections to various Standard Model processes. The extensions concern implementation of Drell--Yan-like processes and include a systematic treatment of the photon-induced contribution in proton--proton collisions and electroweak corrections beyond NLO approximation. There are also technical improvements such as calculation of the forward-backward asymmetry for the neutral current Drell--Yan process. The updated code is suitable for studies of the effects due to EW and QCD radiative corrections to Drell--Yan (and several other) processes at the LHC and for forthcoming high energy proton--proton colliders.
Auxiliary field Monte-Carlo simulation of strong coupling lattice QCD for QCD phase diagram
Terukazu Ichihara; Akira Ohnishi; Takashi Z. Nakano
2014-10-07T23:59:59.000Z
We study the QCD phase diagram in the strong coupling limit with fluctuation effects by using the auxiliary field Monte-Carlo method. We apply the chiral angle fixing technique in order to obtain finite chiral condensate in the chiral limit in finite volume. The behavior of order parameters suggests that chiral phase transition is the second order or crossover at low chemical potential and the first order at high chemical potential. Compared with the mean field results, the hadronic phase is suppressed at low chemical potential, and is extended at high chemical potential as already suggested in the monomer-dimer-polymer simulations. We find that the sign problem originating from the bosonization procedure is weakened by the phase cancellation mechanism; a complex phase from one site tends to be canceled by the nearest neighbor site phase as long as low momentum auxiliary field contributions dominate.
The tau leptons theory and experimental data: Monte Carlo, fits, software and systematic errors
Zbigniew Was
2014-12-09T23:59:59.000Z
Status of tau lepton decay Monte Carlo generator TAUOLA is reviewed. Recent efforts on development of new hadronic currents are presented. Multitude new channels for anomalous tau decay modes and parametrization based on defaults used by BaBar collaboration are introduced. Also parametrization based on theoretical considerations are presented as an alternative. Lesson from comparison and fits to the BaBar and Belle data is recalled. It was found that as in the past, in particular at a time of comparisons with CLEO and ALEPH data, proper fitting, to as detailed as possible representation of the experimental data, is essential for appropriate developments of models of tau decays. In the later part of the presentation, use of the TAUOLA program for phenomenology of W,Z,H decays at LHC is adressed. Some new results, relevant for QED bremsstrahlung in such decays are presented as well.
Bianco, Federica B; Oh, Seung Man; Fierroz, David; Liu, Yuqian; Kewley, Lisa; Graur, Or
2015-01-01T23:59:59.000Z
We present the open-source Python code pyMCZ that determines oxygen abundance and its distribution from strong emission lines in the standard metallicity scales, based on the original IDL code of Kewley & Dopita (2002) with updates from Kewley & Ellison (2008), and expanded to include more recently developed scales. The standard strong-line diagnostics have been used to estimate the oxygen abundance in the interstellar medium through various emission line ratios in many areas of astrophysics, including galaxy evolution and supernova host galaxy studies. We introduce a Python implementation of these methods that, through Monte Carlo (MC) sampling, better characterizes the statistical reddening-corrected oxygen abundance confidence region. Given line flux measurements and their uncertainties, our code produces synthetic distributions for the oxygen abundance in up to 13 metallicity scales simultaneously, as well as for E(B-V), and estimates their median values and their 66% confidence regions. In additi...
Quantum Monte Carlo calculation of the equation of state of neutron matter
Gandolfi, S.; Illarionov, A. Yu.; Schmidt, K. E.; Pederiva, F.; Fantoni, S. [International School for Advanced Studies, SISSA Via Beirut 2/4 I-34014 Trieste (Italy) and INFN, Sezione di Trieste, Trieste (Italy); Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Dipartimento di Fisica dell'Universita di Trento, via Sommarive 14, I-38050 Povo, Trento (Italy) and INFN, Gruppo Collegato di Trento, Trento (Italy); International School for Advanced Studies, SISSA Via Beirut 2/4 I-34014 Trieste (Italy); INFN, Sezione di Trieste, Trieste, Italy and INFM DEMOCRITOS National Simulation Center, Via Beirut 2/4 I-34014 Trieste (Italy)
2009-05-15T23:59:59.000Z
We calculated the equation of state of neutron matter at zero temperature by means of the auxiliary field diffusion Monte Carlo (AFDMC) method combined with a fixed-phase approximation. The calculation of the energy was carried out by simulating up to 114 neutrons in a periodic box. Special attention was given to reducing finite-size effects at the energy evaluation by adding to the interaction the effect due to the truncation of the simulation box, and by performing several simulations using different numbers of neutrons. The finite-size effects due to kinetic energy were also checked by employing the twist-averaged boundary conditions. We considered a realistic nuclear Hamiltonian containing modern two- and three-body interactions of the Argonne and Urbana family. The equation of state can be used to compare and calibrate other many-body calculations and to predict properties of neutron stars.
Monte Carlo procedure for protein folding in lattice model. Conformational rigidity
Olivier Collet
1999-07-19T23:59:59.000Z
A rigourous Monte Carlo method for protein folding simulation on lattice model is introduced. We show that a parameter which can be seen as the rigidity of the conformations has to be introduced in order to satisfy the detailed balance condition. Its properties are discussed and its role during the folding process is elucidated. This method is applied on small chains on two-dimensional lattice. A Bortz-Kalos-Lebowitz type algorithm which allows to study the kinetic of the chains at very low temperature is implemented in the presented method. We show that the coefficients of the Arrhenius law are in good agreement with the value of the main potential barrier of the system.
Ground State Calculations of Confined Hydrogen Molecule H_2 Using Variational Monte Carlo Method
Doma, S B; Amer, A A
2015-01-01T23:59:59.000Z
The variational Monte Carlo method is used to evaluate the ground-state energy of the confined hydrogen molecule, H_2. Accordingly, we considered the case of hydrogen molecule confined by a hard prolate spheroidal cavity when the nuclear positions are clamped at the foci (on-focus case). Also, the case of off-focus nuclei in which the two nuclei are not clamped to the foci is studied. This case provides flexibility for the treatment of the molecular properties by selecting an arbitrary size and shape of the confining spheroidal box. An accurate trial wave function depending on many variational parameters is used for this purpose. The obtained results are in good agreement with the most recent results.
MaGe - a Geant4-based Monte Carlo framework for low-background experiments
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
2008-02-06T23:59:59.000Z
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.