An exposure assessment survey of the Mont Belvieu polyethylene plant
Tucker, Thomas Franklin
1997-01-01
Evaluation of ever changing, complex workplaces can be accomplished with a sound, logical exposure assessment survey (EAS). An EAS was conducted at a polyethylene plant located in southeast Texas to determine the risk of adverse health effects...
Utility spot pricing, California
Schweppe, Fred C.
1982-01-01
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 ...
Wang, Kai
3.3 Word recognition . . . . . . . .Chapter 3 Word-spotting in the wild . . . . . . . . . 3.1recognition . . . . . 3.3.2 Word configuration . . . . . .
Dermoscopy of black-spot poison ivy
Rader, Ryan K; Mu, Ruipu; Shi, Honglan; Stoecker, William V; Hinton, Kristen A
2012-01-01
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.
1982-01-01
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
spot marketss The impact of heat waves on electricity spot
Oldenburg, Carl von Ossietzky Universität
: Electricity Market, Heat Wave, Germany, Climate Change JEL: Q41, Q54 Department of Economics, Carl von power production. During the 2006 heat wave, record electricity spot mar- ket prices of e 2,000 per conomi nburg, D urg D in E ves on nna Pec aus Eise 357 June 20 ics D-2611 Discu cono n electr han
Why sulfonamides are contraindicated in Rocky Mountain spotted fever
Ren, Vicky; Hsu, Sylvia
2014-01-01
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
1995-04-20
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
ARM - Datastreams - aosaeth2spot
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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Comments? We would love to hear from you! Send use0nrwptempmomDatastreamsaosaeth2spot Documentation Data Quality
HotSpot Software Configuration Management Plan
Walker, H; Homann, S G
2009-03-12
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.
The twin spot generator for differential Drosophila
Cai, Long
The twin spot generator for differential Drosophila lineage analysis Ruth Griffin1, Anne Sustar2 based strategies generate mosaic flies with positive readout for only one daughter cell after division. To differentially label both daughter cells, we developed the twin spot generator (TSG) technique, which through
Niayesh Afshordi; Anže Slosar; Yi Wang
2010-12-25
We present a simple inflationary scenario that can produce arbitrarily large spherical underdense or overdense regions embedded in a standard Lambda cold dark matter paradigm, which we refer to as bubbles. We analyze the effect such bubbles would have on the Cosmic Microwave Background (CMB). For super-horizon sized bubble in the vicinity of the last scattering surface, a signal is imprinted onto CMB via a combination of Sach-Wolfe and an early integrated Sach-Wolfe (ISW) effects. Smaller, sub-horizon sized bubbles at lower redshifts (during matter domination and later) can imprint secondary anisotropies on the CMB via Rees-Sciama, late-time ISW and Ostriker-Vishniac effects. Our scenario, and arguably most similar inflationary models, produce bubbles which are over/underdense in potential: in density such bubbles are characterized by having a distinct wall with the interior staying at the cosmic mean density. We show that such models can potentially, with only moderate fine tuning, explain the \\emph{cold spot}, a non-Gaussian feature identified in the Wilkinson Microwave Anisotropy Probe (WMAP) data by several authors. However, more detailed comparisons with current and future CMB data are necessary to confirm (or rule out) this scenario.
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...
Investigations of initiation spot size effects
Clarke, Steven A; Akinci, Adrian A; Leichty, Gary; Schaffer, Timothy; Murphy, Michael J; Munger, Alan; Thomas, Keith A
2010-01-01
As explosive components become smaller, a greater understanding of the effect of initiation spot size on detonation becomes increasingly critical. A series of tests of the effect of initiation spot size will be described. A series of DOI (direct optical initiation) detonators with initiation spots sizes from {approx}50 um to 1000um have been tested to determine laser parameters for threshold firing of low density PETN pressings. Results will be compared with theoretical predictions. Outputs of the initiation source (DOI ablation) have been characterized by a suite of diagnostics including PDV and schlieren imaging. Outputs of complete detonators have been characterized using PDV, streak, and/or schlieren imaging. At present, we have not found the expected change in the threshold energy to spot size relationship for DOI type detonators found in similar earlier for projectiles, slappers and EBWs. New detonators designs (Type C) are currently being tested that will allow the determination of the threshold for spot sizes from 250 um to 105um, where we hope to see change in the threshold vs. spot size relationship. Also, one test of an extremely small diameter spot size (50um) has resulted in preliminary NoGo only results even at energy densities as much as 8 times the energy density of the threshold results presented here. This gives preliminary evidence that 50um spot may be beyond the critical initiation diameter. The constant threshold energy to spot size relationship in the data to date does however still give some insight into the initiation mechanism of DOI detonators. If the DOI initiation mechanism were a 1D mechanism similar to a slapper or a flyer impact, the expected inflection point in the graph would have been between 300um and 500um diameter spot size, within the range of the data presented here. The lack of that inflection point indicates that the DOI initiation mechanism is more likely a 2D mechanism similar to a sphere or rod projectile. We expect to see a three region response as the results from the smaller spot size Type C detonators are completed.
2013-04-18
The HotSpot Health Physics Codes were created to provide emergency response personnel and emergency planners with a fast, field-portable set of software tools for evaluating insidents involving redioactive material. The software is also used for safety-analysis of facilities handling nuclear material. HotSpot provides a fast and usually conservative means for estimation the radiation effects associated with the short-term (less than 24 hours) atmospheric release of radioactive materials.
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
Marcus, Ryan C. [Los Alamos National Laboratory
2012-07-25
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.
Measuring microfocal spots using digital radiography
Fry, David A [Los Alamos National Laboratory; Ewert, Uwe [BAM
2009-01-01
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.
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...
Friction Stir Spot Welding of Advanced High Strength Steels II...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Friction Stir Spot Welding of Advanced High Strength Steels II Friction Stir Spot Welding of Advanced High Strength Steels II 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle...
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
Matías Montes Huidobro: His Theatre
Colecchia, Francesca
1980-07-01
and Carlos Miguel Suárez Radillo, eds., Teatro contempo ráneo hispanoamericano (Madrid: Escelicer, 1971), Vol. Ill, pp. 120-121. (Translations by the author.) 2. Rodríguez Sardinas, p. 121. 3. Matías Montes Huidobro, El tiro por la culata (Cuba... and Carlos Miguel Suárez Radillo, eds., Teatro contempo ráneo hispanoamericano (Madrid: Escelicer, 1971), Vol. Ill, pp. 120-121. (Translations by the author.) 2. Rodríguez Sardinas, p. 121. 3. Matías Montes Huidobro, El tiro por la culata (Cuba...
Modelling of friction stir spot welding
Reilly, Aidan
2013-07-09
1.2 Friction stir process descriptions . . . . . . . . . . . . . . . . . 5 1.2.1 Friction stir welding . . . . . . . . . . . . . . . . . . . 5 1.2.2 Friction stir spot welding (FSSW) . . . . . . . . . . . . 7 1.2.3 Pinless FSSW... processes . . . . . . . 25 2.3.5 Empirical testing and validation . . . . . . . . . . . . . 39 vii 2.3.6 Microstructural modelling . . . . . . . . . . . . . . . . 41 2.3.7 Modelling of related non-welding processes . . . . . . . 42 2.4 Constitutive data...
Friction Stir Spot Welding of Advanced High Strength Steels
Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.
2009-11-13
Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spot welding in advanced high strength steels.
Dynamic Characterization of Spot Welds | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Welds Dynamic Characterization of Spot Welds Presentation from the U.S. DOE Office of Vehicle Technologies "Mega" Merit Review 2008 on February 25, 2008 in Bethesda, Maryland....
An inequality for potentials and the “hot–spots” conjecture
2003-06-04
inequality, by the conformal invariance of Brownian motion, implies a result of Pascu [13] on “hot–spots” for certain symmetric convex domains. ?Supported in ...
Reconfigurability in Embedded Systems using SunSPOT Technology
Simunic, Tajana
Reconfigurability in Embedded Systems using SunSPOT Technology Benjamin Lee Tony Tran Tajana Simunic Rosing Sponsored by: Sun Microsystems #12;Abstract Easy run-time reconfigurability is a very sensor node, SunSPOT, can significantly extend its set of capabilities through run-time reconfiguration
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
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
A NONGAUSSIAN ORNSTEINUHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND
Kallsen, Jan
A NONGAUSSIAN ORNSTEINUHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND DERIVATIVES for analytical pricing of electricity forward and futures contracts. Electricity forward and futures contracts to capture the observed dynamics of electricity spot prices. We also discuss the pricing of European call
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
Zimmerman, G.B.
1997-06-24
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.
Friction Stir Spot Welding of DP780 Carbon Steel
Santella, M. L.; Hovanski, Yuri; Frederick, Alan; Grant, Glenn J.; Dahl, Michael E.
2009-09-15
Friction stir spot welds were made in uncoated and galvannneled DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1-10 s. Increasing tool rotation speed from 800 to 1600 rpm increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap-shear strengths exceeding 10.3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.
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
2013-01-01
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
Finite Cosmology and a CMB Cold Spot
Adler, R.J.; Bjorken, J.D.; Overduin, J.M.; /Stanford U., HEPL
2006-03-20
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.
Hot spot generation in energetic materials created by long-wavelength...
Office of Scientific and Technical Information (OSTI)
Hot spot generation in energetic materials created by long-wavelength infrared radiation Citation Details In-Document Search Title: Hot spot generation in energetic materials...
Wall and laser spot motion in cylindrical hohlraums
Huser, G.; Courtois, C.; Monteil, M.-C.
2009-03-15
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.
Vocal mimicry in the spotted bowerbird Ptilonorhynchus maculatus
Kelley, Laura A
2010-01-01
Vocal mimicry is well documented in songbirds, yet the function of this behaviour is poorly understood. I studied vocal mimicry in a wild population of male spotted bowerbirds Ptilonorhynchus maculatus to determine whether ...
Hot spot-derived shock initiation phenomena in heterogeneous...
Office of Scientific and Technical Information (OSTI)
one type of hot spot 'seed' on the initiation behaviors of explosive formulations. Gas gun-driven plate impact experiments are used to produce well-defined shock inputs into...
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
A Hardware-Driven Profiling Scheme for Identifying Program Hot Spots to Support Runtime Optimization
Hwu, Wen-mei W.
;Motivation and Hot Spot Definition Program Behavior Observations Execution often occurs in distinct phases
Jefferson Lab finds its man Mont (Inside Business) | Jefferson...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
https:www.jlab.orgnewsarticlesjefferson-lab-finds-its-man-mont-inside-business Jefferson Lab finds its man Mont Hugh Montgomery Hugh Montgomery, a British nuclear physicist...
Applications of FLUKA Monte Carlo Code for Nuclear and Accelerator...
Office of Scientific and Technical Information (OSTI)
Applications of FLUKA Monte Carlo Code for Nuclear and Accelerator Physics Citation Details In-Document Search Title: Applications of FLUKA Monte Carlo Code for Nuclear and...
Friction Stir Spot Welding of DP780 Carbon Steel
Santella, Michael L [ORNL; Hovanski, Yuri [ORNL; Frederick, David Alan [ORNL; Grant, Glenn J [ORNL; Dahl, Michael E [ORNL
2010-01-01
Friction stir spot welds were made in uncoated and galvannealed DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1 to 10 s. Increasing tool rotation speed from 800 to 1600 rev min{sup -1} increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap shear strengths exceeding 10 {center_dot} 3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.
FRICTION STIR SPOT WELDING OF 6016 ALUMINUM ALLOY
Mishra, Rajiv S.; Webb, S.; Freeney, T. A.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.; Herling, Darrell R.
2007-01-08
Friction stir spot welding (FSSW) of 6016 aluminum alloy was evaluated with conventional pin tool and new off-center feature tools. The off-center feature tool provides significant control over the joint area. The tool rotation rate was varied between 1000 and 2500 rpm. Maximum failure strength was observed in the tool rotation range of 1200-1500 rpm. The results are interpreted in the context of material flow in the joint and influence of thermal input on microstructural changes. The off-center feature tool concept opens up new possibilities for plunge-type friction stir spot welding.
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
Monte Carlo simulation in systems biology
Schellenberger, Jan
2010-01-01
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
Multiple quadrature by Monte Carlo techniques
Voss, John Dietrich
1966-01-01
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...
REAL TIME ULTRASONIC ALUMINUM SPOT WELD MONITORING SYSTEM
Regalado, W. Perez; Chertov, A. M.; Maev, R. Gr. [Institute for Diagnostic Imaging Research, Physics Department, University of Windsor, 292 Essex Hall, 401 Sunset Ave. N9B 3P4 Windsor, Ontario (Canada)
2010-02-22
Aluminum alloys pose several properties that make them one of the most popular engineering materials: they have excellent corrosion resistance, and high weight-to-strength ratio. Resistance spot welding of aluminum alloys is widely used today but oxide film and aluminum thermal and electrical properties make spot welding a difficult task. Electrode degradation due to pitting, alloying and mushrooming decreases the weld quality and adjustment of parameters like current and force is required. To realize these adjustments and ensure weld quality, a tool to measure weld quality in real time is required. In this paper, a real time ultrasonic non-destructive evaluation system for aluminum spot welds is presented. The system is able to monitor nugget growth while the spot weld is being made. This is achieved by interpreting the echoes of an ultrasound transducer located in one of the welding electrodes. The transducer receives and transmits an ultrasound signal at different times during the welding cycle. Valuable information of the weld quality is embedded in this signal. The system is able to determine the weld nugget diameter by measuring the delays of the ultrasound signals received during the complete welding cycle. The article presents the system performance on aluminum alloy AA6022.
Spot Convenience Yield Models for Energy Michael Ludkovski
Ludkovski, Mike
is more appropriate for energy commodities. Because a commodity can be consumed its price is a combinationSpot Convenience Yield Models for Energy Assets Michael Ludkovski and Ren´e Carmona August 2003 1 Introduction As the energy markets continue to evolve, valuation of energy-linked assets has been one
PASSIVE BEHAVIOR BY THE SPOTTED DOLPHIN, STENELLA ATTENUATA, IN
PASSIVE BEHAVIOR BY THE SPOTTED DOLPHIN, STENELLA ATTENUATA, IN TUNA PURSE SEINE NETS The purse and then recognized for its contribution to incidental mortality in 1975 is termed here "passive" behavior were recorded after each ofthe 25 net sets in which the rescue raft was used. The underwater passive
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
Janée, Greg
how far off-nadir the focus point is. For the SPOT HRV sensors it can range from -27 (west) to +27 (east) of the ground track. In SCIE metadata records the mirror angle is described by an integer "mirror and incidence angle values recorded in the SCIE metadata, respectively, and if s is the incidence angle computed
WPP, No.111: Syllabification, Sonority, and Spoken Word Segmentation: Evidence from Word-Spotting
Bishop, Jason; Toda, Kristen
2012-01-01
segmentation in French: Word- spotting data. Brain andH. Mitterer. 2010. Possible words and fixed stress in theAmherst. McQueen, J. 1996. Word Spotting. Language and
An Activity-Based Sensor Networks Course for Undergraduates with Sun SPOT Devices
Bulusu, Nirupama
An Activity-Based Sensor Networks Course for Undergraduates with Sun SPOT Devices Damon Tyman that had previously been entirely lecture-based. For the laboratory exercises, we utilized Sun's Java-programmable Sun SPOT [7] sensor network technology. We found the Sun SPOT based laboratory activities to be quite
FROM WORD-SPOTTING TO OOV MODELING Paul Fitzpatrick (6345g11)
1 FROM WORD-SPOTTING TO OOV MODELING Paul Fitzpatrick (6345g11) 6.345, Automatic Speech Recognition, Spring 2001 1 Introduction This paper explores one dimension along which word spotting and speech recognition differ: the nature of the background model. In word spotting, a relatively small number
Animation and Visualization of Spot Prices via Quadratized Power Flow Analysis
Animation and Visualization of Spot Prices via Quadratized Power Flow Analysis A. P. Sakis@attbi.com Abstract This paper presents a new model for efficient calculation of spot prices and animation and visualization of spot price evolution as the system operating point is changing. The computational method
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
Magnetic fields, spots and weather in chemically peculiar stars
O. Kochukhov
2007-11-30
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.
Quantum Mechanical Single Molecule Partition Function from Path Integral Monte Carlo Simulations
Chempath, Shaji; Bell, Alexis T.; Predescu, Cristian
2008-01-01
calculated from path integral Monte Carlo(PIMC) and harmoniccalculated from path integral Monte Carlo (PIMC) andFunction from Path Integral Monte Carlo Simulations Shaji
Imaging of semiconductors using a flying laser spot scanning system
Richardson, Thomas William
1982-01-01
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)
2014-02-18
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.
Monte Carlo Tools for Jet Quenching
Korinna Zapp
2011-09-07
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
2011-01-01
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 ...
A MONTE CARLO SIMULATION OF WATER FLOW IN VARIABLY ...
1910-10-30
Se utiliza un m?etodo de simulaci?on Monte Carlo para estudiar el flujo de aguas ... A Monte Carlo simulation method is employed to study groundwater flow in ...
Smart detectors for Monte Carlo radiative transfer
Maarten Baes
2008-09-11
Many optimization techniques have been invented to reduce the noise that is inherent in Monte Carlo radiative transfer simulations. As the typical detectors used in Monte Carlo simulations do not take into account all the information contained in the impacting photon packages, there is still room to optimize this detection process and the corresponding estimate of the surface brightness distributions. We want to investigate how all the information contained in the distribution of impacting photon packages can be optimally used to decrease the noise in the surface brightness distributions and hence to increase the efficiency of Monte Carlo radiative transfer simulations. We demonstrate that the estimate of the surface brightness distribution in a Monte Carlo radiative transfer simulation is similar to the estimate of the density distribution in an SPH simulation. Based on this similarity, a recipe is constructed for smart detectors that take full advantage of the exact location of the impact of the photon packages. Several types of smart detectors, each corresponding to a different smoothing kernel, are presented. We show that smart detectors, while preserving the same effective resolution, reduce the noise in the surface brightness distributions compared to the classical detectors. The most efficient smart detector realizes a noise reduction of about 10%, which corresponds to a reduction of the required number of photon packages (i.e. a reduction of the simulation run time) of 20%. As the practical implementation of the smart detectors is straightforward and the additional computational cost is completely negligible, we recommend the use of smart detectors in Monte Carlo radiative transfer simulations.
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
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
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
Quantum Monte Carlo Calculations of Light Nuclei
Steven C. Pieper
2004-10-27
Variational Monte Carlo and Green's function Monte Carlo are powerful tools for calculations of properties of light nuclei using realistic two-nucleon and three-nucleon potentials. Recently the GFMC method has been extended to multiple states with the same quantum numbers. The combination of the Argonne v_18 two-nucleon and Illinois-2 three-nucleon potentials gives a good prediction of many energies of nuclei up to 12C. A number of other recent results are presented: comparison of binding energies with those obtained by the no-core shell model; the incompatibility of modern nuclear Hamiltonians with a bound tetra-neutron; difficulties in computing RMS radii of very weakly bound nuclei, such as 6He; center-of-mass effects on spectroscopic factors; and the possible use of an artificial external well in calculations of neutron-rich isotopes.
Quantum Monte Carlo by message passing
Bonca, J.; Gubernatis, J.E.
1993-01-01
We summarize results of quantum Monte Carlo simulations of the degenerate single-impurity Anderson model using the impurity algorithm of Hirsch and Fye. Using methods of Bayesian statistical inference, coupled with the principle of maximum entropy, we extracted the single-particle spectral density from the imaginary-time Green's function. The variations of resulting spectral densities with model parameters agree qualitatively with the spectral densities predicted by NCA calculations. All the simulations were performed on a cluster of 16 IBM R6000/560 workstations under the control of the message-passing software PVM. We described the trivial parallelization of our quantum Monte Carlo code both for the cluster and the CM-5 computer. Other issues for effective parallelization of the impurity algorithm are also discussed.
Quantum Monte Carlo by message passing
Bonca, J.; Gubernatis, J.E.
1993-05-01
We summarize results of quantum Monte Carlo simulations of the degenerate single-impurity Anderson model using the impurity algorithm of Hirsch and Fye. Using methods of Bayesian statistical inference, coupled with the principle of maximum entropy, we extracted the single-particle spectral density from the imaginary-time Green`s function. The variations of resulting spectral densities with model parameters agree qualitatively with the spectral densities predicted by NCA calculations. All the simulations were performed on a cluster of 16 IBM R6000/560 workstations under the control of the message-passing software PVM. We described the trivial parallelization of our quantum Monte Carlo code both for the cluster and the CM-5 computer. Other issues for effective parallelization of the impurity algorithm are also discussed.
March market review. [Spot market prices for uranium (1993)
Not Available
1993-04-01
The spot market price for uranium in unrestricted markets weakened further during March, and at month end, the NUEXCO Exchange Value had fallen $0.15, to $7.45 per pound U3O8. The Restricted American Market Penalty (RAMP) for concentrates increased $0.15, to $2.55 per pound U3O8. Ample UF6 supplies and limited demand led to a $0.50 decrease in the UF6 Value, to $25.00 per kgU as UF6, while the RAMP for UF6 increased $0.75, to $5.25 per kgU. Nine near-term uranium transactions were reported, totalling almost 3.3 million pounds equivalent U3O8. This is the largest monthly spot market volume since October 1992, and is double the volume reported in January and February. The March 31 Conversion Value was $4.25 per kgU as UF6. Beginning with the March 31 Value, NUEXCO now reports its Conversion Value in US dollars per kilogram of uranium (US$/kgU), reflecting current industry practice. The March loan market was inactive with no transactions reported. The Loan Rate remained unchanged at 3.0 percent per annum. Low demand and increased competition among sellers led to a one-dollar decrease in the SWU Value, to $65 per SWU, and the RAMP for SWU declined one dollar, to $9 per SWU.
Transformation from spots to waves in a model of actin pattern formation
Stephen Whitelam; Till Bretschneider; Nigel J. Burroughs
2009-05-18
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.
Basden, Alastair
2015-01-01
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.
Status of Monte-Carlo Event Generators
Hoeche, Stefan; /SLAC
2011-08-11
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.
A Monte Carlo algorithm for degenerate plasmas
Turrell, A.E. Sherlock, M.; Rose, S.J.
2013-09-15
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.
Marcus, Ryan C. [Los Alamos National Laboratory
2012-07-24
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.
Monte Carlo errors with less errors
Ulli Wolff
2006-11-29
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.
Multicanonical hybrid Monte Carlo for compact QED
G. Arnold; Th. Lippert; K. Schilling
1999-09-14
We demonstrate that substantial progress can be achieved in the study of the phase structure of 4-dimensional compact QED by a joint use of hybrid Monte Carlo and multicanonical algorithms, through an efficient parallel implementation. This is borne out by the observation of considerable speedup of tunnelling between the metastable states, close to the phase transition, on the Wilson line. Our approach leads to a general parallelization scheme for the efficient stochastic sampling of systems where (a part of) the Hamiltonian involves the total action or energy in each update step.
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 QA:QA J-E-1 SECTION J APPENDIX ECoopButtePowerEdisto Electric Coop, Incsource History View New PagesMonte Carlo (EMCEE)
Eolica Montes de Cierzo | 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 QA:QA J-E-1 SECTION J APPENDIX E LIST OFAMERICA'SHeavy Electricals LtdEcowindEnvironmental SolarMontes de Cierzo Jump
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
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
Spot Convenience Yield Models for the Energy Markets Rene Carmona and Michael Ludkovski
Carmona, Rene
. We review that part of the literature on energy spot price models which involves convenience yield and phrases. Spot price, convenience yield, energy markets. 1 #12;2 REN´E CARMONA AND MICHAEL LUDKOVSKI is more appropriate for energy commodities. Because a commodity can be consumed, its price
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
Fan, Jianqing
2008-01-01
Statistics and Its Interface Volume 1 (2008) 279288 Spot volatility estimation for high-frequency data Jianqing Fan and Yazhen Wang The availability of high-frequency intraday data allows us and volatility of an asset and investigates kernel type estimators of spot volatility based on high-frequency
A NON-GAUSSIAN ORNSTEIN-UHLENBECK PROCESS FOR ELECTRICITY SPOT PRICE MODELING AND
Kallsen, Jan
A 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 to capture the observed dynamics of electricity spot prices. We also discuss the pricing of European call
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
Evaluation of Monte Carlo Electron-Transport Algorithms in the...
Office of Scientific and Technical Information (OSTI)
Evaluation of Monte Carlo Electron-Transport Algorithms in the Integrated Tiger Series Codes for Stochastic-Media Simulations. Citation Details In-Document Search Title: Evaluation...
Quantum Monte Carlo Calculations of Light Nuclei Using Chiral...
Office of Scientific and Technical Information (OSTI)
Details In-Document Search This content will become publicly available on November 4, 2015 Title: Quantum Monte Carlo Calculations of Light Nuclei Using Chiral Potentials...
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.
2015-06-04
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
Multilevel Monte Carlo simulation of Coulomb collisions
Rosin, M.S.; Ricketson, L.F.; Dimits, A.M.; Caflisch, R.E.; Cohen, B.I.
2014-10-01
We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ?, the computational cost of the method is O(?{sup ?2}) or O(?{sup ?2}(ln?){sup 2}), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(?{sup ?3}) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ?=10{sup ?5}. We discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.
Quantum Monte Carlo methods for nuclear physics
J. Carlson; S. Gandolfi; F. Pederiva; Steven C. Pieper; R. Schiavilla; K. E. Schmidt; R. B. Wiringa
2015-04-29
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.
Metallic lithium by quantum Monte Carlo
Sugiyama, G.; Zerah, G.; Alder, B.J.
1986-12-01
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.
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.
2014-10-19
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
Quantum Monte Carlo methods for nuclear physics
Carlson, Joseph A.; Gandolfi, Stefano; Pederiva, Francesco; Pieper, Steven C.; Schiavilla, Rocco; Schmidt, K. E,; Wiringa, Robert B.
2014-10-19
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.
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)
2014-06-01
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.
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
Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots
Zhang, Jian-Shi; Giometti, C.S.; Tollaksen, S.L.
1987-09-04
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.
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)
2014-10-01
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.
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
2014-10-13
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
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
May market review. [Spot market prices for uranium (1993)
Not Available
1993-06-01
Seven uranium transactions totalling nearly three million pounds equivalent U3O8 were reported during May, but only two, totalling less than 200 thousand pounds equivalent U3O8, involved concentrates. As no discretionary buying occurred during the month, and as near-term supply and demand were in relative balance, prices were steady, while both buyers and sellers appeared to be awaiting some new market development to signal the direction of future spot-market prices. The May 31, 1993, Exchange Value and the Restricted American market Penalty (RAMP) for concentrates were both unchanged at $7.10, and $2.95 per pound U3O8, respectively. NUEXCO's judgement was that transactions for significant quantities of uranium concentrates that were both deliverable in and intended for consumption in the USA could have been concluded on May 31 at $10.05 per pound U3O8. Two near-term concentrate transactions were reported in which one US utility purchased less than 200 thousand pounds equivalent U3O8 from two separate sellers. These sales occurred at price levels at or near the May 31 Exchange Value plus RAMP. No long-term uranium transactions were reported during May. Consequently, the UF6 Value decreased $0.20 to $24.30 per kgU as UF6, reflecting some weakening of the UF6 market outside the USA.
DRAMATIC CHANGE IN JUPITER'S GREAT RED SPOT FROM SPACECRAFT OBSERVATIONS
Simon, Amy A.; Wong, Michael H.; De Pater, Imke; Rogers, John H.; Orton, Glenn S.; Carlson, Robert W.; Asay-Davis, Xylar; Marcus, Philip S.
2014-12-20
Jupiter's Great Red Spot (GRS) is one of its most distinct and enduring features. Since the advent of modern telescopes, keen observers have noted its appearance and documented a change in shape from very oblong to oval, confirmed in measurements from spacecraft data. It currently spans the smallest latitude and longitude size ever recorded. Here we show that this change has been accompanied by an increase in cloud/haze reflectance as sensed in methane gas absorption bands, increased absorption at wavelengths shorter than 500 nm, and increased spectral slope between 500 and 630 nm. These changes occurred between 2012 and 2014, without a significant change in internal tangential wind speeds; the decreased size results in a 3.2 day horizontal cloud circulation period, shorter than previously observed. As the GRS has narrowed in latitude, it interacts less with the jets flanking its north and south edges, perhaps allowing for less cloud mixing and longer UV irradiation of cloud and aerosol particles. Given its long life and observational record, we expect that future modeling of the GRS's changes, in concert with laboratory flow experiments, will drive our understanding of vortex evolution and stability in a confined flow field crucial for comparison with other planetary atmospheres.
WE-E-BRE-04: Dual Focal Spot Dose Painting for Precision Preclinical Radiobiological Investigations
Stewart, J; Lindsay, P; Jaffray, D
2014-06-15
Purpose: Recent progress in small animal radiotherapy systems has provided the foundation for delivering the heterogeneous, millimeter scale dose distributions demanded by preclinical radiobiology investigations. Despite advances in preclinical dose planning, delivery of highly heterogeneous dose distributions is constrained by the fixed collimation systems and large x-ray focal spot common in small animal radiotherapy systems. This work proposes a dual focal spot dose optimization and delivery method with a large x-ray focal spot used to deliver homogeneous dose regions and a small focal spot to paint spatially heterogeneous dose regions. Methods: Two-dimensional dose kernels were measured for a 1 mm circular collimator with radiochromic film at 10 mm depth in a solid water phantom for the small and large x-ray focal spots on a recently developed small animal microirradiator. These kernels were used in an optimization framework which segmented a desired dose distribution into low- and high-spatial frequency regions for delivery by the large and small focal spot, respectively. For each region, the method determined an optimal set of stage positions and beam-on times. The method was demonstrated by optimizing a bullseye pattern consisting of 0.75 mm radius circular target and 0.5 and 1.0 mm wide rings alternating between 0 and 2 Gy. Results: Compared to a large focal spot technique, the dual focal spot technique improved the optimized dose distribution: 69.2% of the optimized dose was within 0.5 Gy of the intended dose for the large focal spot, compared to 80.6% for the dual focal spot method. The dual focal spot design required 14.0 minutes of optimization, and will require 178.3 minutes for automated delivery. Conclusion: The dual focal spot optimization and delivery framework is a novel option for delivering conformal and heterogeneous dose distributions at the preclinical level and provides a new experimental option for unique radiobiological investigations. Funding Support: this work is supported by funding the National Sciences and Engineering Research Council of Canada, and a Mitacs-accelerate fellowship. Conflict of Interest: Dr. Lindsay and Dr. Jaffray are listed as inventors of the small animal microirradiator described herein. This system has been licensed for commercial development.
Iterative acceleration methods for Monte Carlo and deterministic criticality calculations
Urbatsch, T.J.
1995-11-01
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.
Calculation of the fast ion tail distribution for a spherically symmetric hot spot
McDevitt, C. J.; Tang, X.-Z.; Guo, Z.; Berk, H. L.
2014-10-15
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.
Informing the DebateInforming the DebateInforming the Debate Stored Blood Spots
Riley, Shawn J.
blood draw. Sometimes a nurse or technician might offer a brief word of explanation as to why the blood, who could be an adult now, gave informed consent for this research to be done with their blood spots
Assessment of Prices of Natural Gas Futures Contracts As A Predictor of Realized Spot Prices, An
Reports and Publications (EIA)
2005-01-01
This article compares realized Henry Hub spot market prices for natural gas during the three most recent winters with futures prices as they evolve from April through the following February, when trading for the March contract ends.
Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems...
Office of Scientific and Technical Information (OSTI)
Hot Spots in Thermal Process Off-Gas Systems Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and...
April market review. [Spot market prices for uranium (1993)
Not Available
1993-05-01
The spot market price for uranium outside the USA weakened further during April, and at month end, the NUEXCO Exchange Value had fallen $0.35, to $7.10 per pound U3O8. This is the lowest Exchange Value observed in nearly twenty years, comparable to Values recorded during the low price levels of the early 1970s. The Restricted American Market Penalty (RAMP) for concentrates increased $0.40, to $2.95 per pound U3O8. Transactions for significant quantities of uranium concentrates that are both deliverable in and intended for consumption in the USA could have been concluded on April 30 at $10.05 per pound U3O8, up $0.05 from the sum of corresponding March Values. Four near-term concentrates transactions were reported, totalling nearly 1.5 million pounds equivalent U3O8. One long-term sale was reported. The UF6 Value also declined, as increased competition among sellers led to a $0.50 decrease, to $24.50 per kgU as UF6. However, the RAMP for UF6 increased $0.65, to $5.90 per kgU as UF6, reflecting an effective US market level of $30.40 per kgU. Two near term transactions were reported totalling approximately 1.1 million pounds equivalent U3O8. In total, eight uranium transactions totalling 28 million pounds equivalent U3O8 were reported, which is about average for April market activity.
The economic feasibility of computerized spot markets for feeder cattle in Texas
Glazener, Gretchen
1979-01-01
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...
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)
2014-06-15
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.
Kinetic Monte Carlo simulations of nanocrystalline film deposition
Ruan, Shiyun
A full diffusion kinetic Monte Carlo algorithm is used to model nanocrystalline film deposition, and study the mechanisms of grain nucleation and microstructure formation in such films. The major finding of this work is ...
Monte Carlo Hauser-Feshbach Calculations of Prompt Fission Neutrons...
Office of Scientific and Technical Information (OSTI)
Technical Report: Monte Carlo Hauser-Feshbach Calculations of Prompt Fission Neutrons and Gamma Rays: Application to Thermal Neutron-Induced Fission Reactions on U-235 and Pu-239...
A Monte Carlo tool for multi-node reliability evaluation
Thalasila, Chander Pravin
1993-01-01
-Area Reliability Program(NARP) is based on the random sampling of generator and transmission line status for each hour. Monte Carlo Approach for Estimating Contingency Statistics along with the Evaluation Subroutine(MACS-ES) advances the generation...
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
2015-01-01
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.
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)
2013-09-15
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 Wang, Huanran; Zhou, Fenghua
2014-08-07
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.
Experimental comparison of various techniques for spot size measurement of high-energy x-ray source
Wang, Yi; Chen, Nan; Cheng, Jinming; Li, Chenggang; Dai, Wenhua; Li, Hong; Long, Quanhong; Shi, Jinshui; Deng, Jianjun
2015-01-01
In the experiment of flash-radiography, the quality of acquired image strongly depends on the focal size of the x-ray source spot. A variety of techniques based on imaging of pinhole, slit and rollbar are adopted to measure the focal spot size of the Dragon-I linear induction accelerator. The image of pinhole provides a two-dimensional distribution of the x-ray spot, while those of slit and rollbar give a line-spread distribution and an edge-spread distribution, respectively. The spot size characterized by full-width at half-maximum and that characterized by the LANL definition are calculated for comparison.
Real-time spot size camera for pulsed high-energy radiographic machines
Watson, S.A.
1993-06-01
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.
1993-01-01
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.
A dynamical model for the CSO-MSO-FRII evolution: hints from hot spot properties
M. Perucho; J. M. Marti
2004-07-28
Compact Symmetric Objects (CSOs) are considered the young counterparts of large doubles according to advance speeds measured or inferred from spectral ageing. Here we present a simple power law model for the CSO/FRII evolution based on the study of sources with well defined hot-spots. The luminosity of the hot spots is estimated under minimum energy conditions. The advance of the source is considered to proceed in ram pressure equilibrium with the ambient medium. Finally, we also assume that the jets feeding the hot spots are relativistic and have a time dependent power. Comparison with observational data allows to interpret the CSO-FRII evolution in terms of decreasing jet power with time.
Chemical spots and their dynamical evolution on HgMn stars
Korhonen, Heidi; Briquet, Maryline; Gonzalez, Federico; Savanov, Igor
2010-01-01
Our recent studies of late B-type stars with HgMn peculiarity revealed for the first time the presence of fast dynamical evolution of chemical spots on their surfaces. These observations suggest a hitherto unknown physical process operating in the stars with radiative outer envelopes. Furthermore, we have also discovered existence of magnetic fields on these stars that have up to now been thought to be non-magnetic. Here we will discuss the dynamical spot evolution on HD 11753 and our new results on magnetic fields on AR Aur.
Six years of monitoring annual changes in a freshwater marsh with SPOT HRV data
Mackey, H.E. Jr.
1992-12-01
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.
1992-01-01
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.
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)
2013-11-15
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.
Wang, Z; Gao, M
2014-06-01
Purpose: Monte Carlo simulation plays an important role for proton Pencil Beam Scanning (PBS) technique. However, MC simulation demands high computing power and is limited to few large proton centers that can afford a computer cluster. We study the feasibility of utilizing cloud computing in the MC simulation of PBS beams. Methods: A GATE/GEANT4 based MC simulation software was installed on a commercial cloud computing virtual machine (Linux 64-bits, Amazon EC2). Single spot Integral Depth Dose (IDD) curves and in-air transverse profiles were used to tune the source parameters to simulate an IBA machine. With the use of StarCluster software developed at MIT, a Linux cluster with 2–100 nodes can be conveniently launched in the cloud. A proton PBS plan was then exported to the cloud where the MC simulation was run. Results: The simulated PBS plan has a field size of 10×10cm{sup 2}, 20cm range, 10cm modulation, and contains over 10,000 beam spots. EC2 instance type m1.medium was selected considering the CPU/memory requirement and 40 instances were used to form a Linux cluster. To minimize cost, master node was created with on-demand instance and worker nodes were created with spot-instance. The hourly cost for the 40-node cluster was $0.63 and the projected cost for a 100-node cluster was $1.41. Ten million events were simulated to plot PDD and profile, with each job containing 500k events. The simulation completed within 1 hour and an overall statistical uncertainty of < 2% was achieved. Good agreement between MC simulation and measurement was observed. Conclusion: Cloud computing is a cost-effective and easy to maintain platform to run proton PBS MC simulation. When proton MC packages such as GATE and TOPAS are combined with cloud computing, it will greatly facilitate the pursuing of PBS MC studies, especially for newly established proton centers or individual researchers.
Quantum Monte Carlo Calculations of Light Nuclei Using Chiral Potentials
J. E. Lynn; J. Carlson; E. Epelbaum; S. Gandolfi; A. Gezerlis; A. Schwenk
2014-11-09
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.
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
Assessing the Degree of Spot Market Integration For U.S. Natural Gas: Evidence from Daily Price Data
Assessing 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: Zhongmin.wang@BusEco.monash.edu.au #12;Assessing the Degree of Spot Market Integration For U.S. Natural Gas
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 University e-mail: tdm2@cornell.edu Abstract Earlier research has shown that the behavior of spot prices. This model captures the observed price spikes that occur in these markets, particularly during the summer
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
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
The spotted seatrout (Cynoscion neb-ulosus) is an estuarine-dependent
(Fish and Mowbray, 1970; Mok and Gilmore, 1983). Direct involvement of sound production with spawning@mrd.dnr.state.sc.us Myra C. Brouwer South Atlantic Fishery Management Council One Southpark Center; suite 306 Charleston. Daniel III and M. W. Sprague. 1999. Characterization of critical spawning habitats of weakfish, spotted
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
Automatic Feedback-Directed Object Inlining in the Java HotSpotTM Virtual Machine
Mössenböck, Hanspeter
to be replaced by address arithmetic. We implemented this optimization for Sun Microsystems' Java HotSpotTM VM analysis. The garbage collector ensures that groups of colocated objects are not split: it copies groups This work was supported by Sun Microsystems, Inc. c ACM, 2007. This is the author's version of the work
Chandra Observations of Cygnus A: Magnetic Field Strengths in the Hot Spots of a Radio Galaxy
A. S. Wilson; A. J. Young; P. L. Shopbell
2000-09-19
We report X-ray observations of the powerful radio galaxy Cygnus A with the Chandra X-ray Observatory. This letter focuses on the radio hot spots, all four of which are detected in X-rays with a very similar morphology to their radio structure. X-ray spectra have been obtained for the two brighter hot spots (A and D). Both are well described by a power law with photon index \\Gamma = 1.8 \\pm 0.2 absorbed by the Galactic column in the direction of Cygnus A. Thermal X-ray models require too high gas densities and may be ruled out. The images and spectra strongly support synchrotron self-Compton models of the X-ray emission, as proposed by Harris, Carilli & Perley on the basis of ROSAT imaging observations. Such models indicate that the magnetic field in each of the brighter hot spots is 1.5 \\times 10^-4 gauss, with an uncertainty of a few tens of percent. This value is close to the equipartition field strengths assuming no protons are present. The possibility that the X-rays are synchrotron radiation is briefly discussed, but not favored. We speculate that production of the \\gamma \\sim 10^7 electrons necessary for X-ray synchrotron radiation from hot spots is inhibited when the external gas density is high, as is the case when the radio galaxy is within a cooling flow.
An accurate performance model of shared buffer ATM switches under hot spot traffic
Atiquzzaman, Mohammed
An accurate performance model of shared buffer ATM switches under hot spot traffic M. Saleha , M Abstract Asynchronous transfer mode (ATM) switches based on shared buffering are known to have better performance and buffer utilization than input or output queued switches. Shared buffer switches do not suffer
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
Water ice in the dark dune spots of Richardson crater on Mars
Kereszturi, A; Schmidt, F
2010-01-01
In this study we assess the presence, nature and properties of ices - in particular water ice - that occur within these spots using HIRISE and CRISM observations, as well as the LMD Global Climate Model. Our studies focus on Richardson crater (72{\\deg}S, 179{\\deg}E) and cover southern spring and summer (LS 175{\\deg} - 17 341{\\deg}). Three units have been identified of these spots: dark core, gray ring and bright halo. Each unit show characteristic changes as the season progress. In winter, the whole area is covered by CO2 ice with H2O ice contamination. Dark spots form during late winter and early spring. During spring, the dark spots are located in a 10 cm thick depression compared to the surrounding bright ice-rich layer. They are spectrally characterized by weak CO2 ice signatures that probably result from spatial mixing of CO2 ice rich and ice free regions within pixels, and from mixing of surface signatures due to aerosols scattering. The bright halo shaped by winds shows stronger CO2 absorptions than th...
Dynamic Interactions in the Western United States Electricity Spot Markets Christine A. Jerko
are balanced on a knife-edge with weather grid reliability, grid dynamics, transmission dynamicsDynamic 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
Integration of Contracted Renewable Energy and Spot Market Supply to Serve
Oren, Shmuel S.
. In close analogy to the policy coordination that is taking place for renewable energy integration, demandIntegration 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
On the mechanism of operation of a cathode spot cell in a vacuum arc
Mesyats, G. A.; Petrov, A. A.; Bochkarev, M. B.; Barengolts, S. A.
2014-05-05
The erosive structures formed on a tungsten cathode as a result of the motion of the cathode spot of a vacuum arc over the cathode surface have been examined. It has been found that the average mass of a cathode microprotrusion having the shape of a solidified jet is approximately equal to the mass of ions removed from the cathode within the lifetime of a cathode spot cell carrying a current of several amperes. The time of formation of a new liquid-metal jet under the action of the reactive force of the plasma ejected by the cathode spot is about 10?ns, which is comparable to the lifetime of a cell. The growth rate of a liquid-metal jet is ?10{sup 4}?cm/s. The geometric shape and size of a solidified jet are such that a new explosive emission center (spot cell) can be initiated within several nanoseconds during the interaction of the jet with the dense cathode plasma. This is the underlying mechanism of the self-sustained operation of a vacuum arc.
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
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
IEEE TRANSACTIONS ON SERVICES COMPUTING, 201X 1 Spot Transit: Cheaper Internet Transit
Li, Baochun
Internet transit market, where transit is sold using the under-utilized backbone capacity at a lower price capacity is sold at a lower price to compliment the traditional contract-based market. To serve the spot. The providers can improve profit by capitalizing the perishable capacity, and customers can buy transit
Demography of the California Spotted Owl in the Sierra National Forest and
/or deformed live trees, and decaying wood on the forest floor. Pairs in Sierra conifer forests use home ranges than local in scope, such as weather and/or prey populations. Local forest management may compound and timber harvest, weather, and prey availability. California spotted owls (Strix occidentalis occidentalis
Optimal Spot Market Inventory Strategies in the Presence of Cost and Price Risk
Guo, Xin
it is cheapest..." Thus, consider a utility that purchases electricity on the spot market in anticipation, consider a firm that owns electric power storage technology. Initially, firms considered such technology as a way to improve the efficiency of electricity generation technology, but as observed in [30
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
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
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
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
Feature-Independent Action Spotting Without Human Localization, Segmentation or Frame-wise Tracking
Foroosh, Hassan
Feature-Independent Action Spotting Without Human Localization, Segmentation or Frame-wise Tracking Chuan Sun, Marshall Tappen, Hassan Foroosh Department of EECS, Division of Computer Science, University solution requires no human localization, segmentation, or framewise tracking. This is achieved by treating
Draft 1e ESTIMATING THE VOLATILITY OF SPOT PRICES IN RESTRUCTURED ELECTRICITY MARKETS depends critically on the specification and estimation of the stochastic process that describes the price path. Accurate valuation of claims based on competitive electricity prices has proved problematic
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
Physical parameters in the hot spots and jets of Compact Symmetric Objects
Manuel Perucho; Jose Maria Marti
2001-11-30
We present a model to determine the physical parameters of jets and hot spots of a sample of CSOs under very basic assumptions like synchrotron emission and minimum energy conditions. Based on this model we propose a simple evolutionary scenario for these sources assuming that they evolve in ram pressure equilibrium with the external medium and constant jet power. The parameters of our model are constrained from fits of observational data (radio luminosity, hot spot radius and hot spot advance speed) versus projected linear size. From these plots we conclude that CSOs evolve self-similarly and that their radio luminosity increases with linear size along the first kiloparsec. Assuming that the jets feeding CSOs are relativistic from both kinematical and thermodynamical points of view, we use the values of the pressure and particle number density within the hot spots to estimate the fluxes of momentum (thrust), energy, and particles of these relativistic jets. The mean jet power obtained in this way is within an order of magnitude that inferred for FRII sources, which is consistent with CSOs being the possible precursors of large doubles. The inferred flux of particles corresponds to, for a barionic jet, about a 10% of the mass accreted by a black hole of $10^8 {\\rm M_{\\odot}}$ at the Eddington limit, pointing towards a very efficient conversion of accretion flow into ejection, or to a leptonic composition of jets.
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
Srinivasan, Bhuvana; Tang, Xian-Zhu
2014-10-15
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.
The Halo, Hot Spots and Jet/Cloud Interaction of PKS 2153--69
A. J. Young; A. S. Wilson; S. J. Tingay; S. Heinz
2004-12-21
We report Chandra X-ray Observatory and 1.4 GHz Australian Long Baseline Array (LBA) observations of the radio galaxy PKS 2153--69 and its environment. The Chandra image reveals a roughly spherical halo of hot gas extending out to 30 kpc around PKS 2153--69. Two depressions in the surface brightness of the X-ray halo correspond to the large scale radio lobes, and interpreting these as cavities inflated with radio plasma we infer a jet power of 4x10^42 erg/s. Both radio lobes contain hot spots that are detected by Chandra. In addition, the southern hot spot is detected in the 1.4 GHz LBA observation, providing the highest linear resolution image of a radio lobe hot spot to date. The northern hot spot was not detected in the LBA observation. The radio to X-ray spectra of the hot spots are consistent with a simple power law emission model. The nucleus has an X-ray spectrum typical of a type 1 active galactic nucleus, and the LBA observation shows a one-sided nuclear jet on 0.1" scales. Approximately 10" northeast of the nucleus, X-ray emission is associated with an extra-nuclear cloud. The X-ray emission from the cloud can be divided into two regions, an unresolved western component associated with a knot of radio emission (in a low resolution map), and a spatially extended eastern component aligned with the pc-scale jet and associated with highly ionized optical line-emitting clouds. The X-ray spectrum of the eastern component is very soft (Gamma > 4.0 for a power law model or kT ~0.22 keV for a thermal plasma). The LBA observation did not detect compact radio emission from the extra-nuclear cloud. (Abstract truncated).
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)
2014-07-10
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.
Monte Carlo: in the beginning and some great expectations
Metropolis, N.
1985-01-01
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.
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
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
Path Integral Monte-Carlo Calculations for Relativistic Oscillator
Alexandr Ivanov; Oleg Pavlovsky
2014-11-11
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.
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
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
Particle Physics Phenomenology 1. Introduction and Monte Carlo techniques
Sjöstrand, Torbjörn
Particle Physics Phenomenology 1. Introduction and Monte Carlo techniques Torbj¨orn Sj: Introduction and MC techniques slide 2/81 #12;Course objectives Improve understanding of how physics at the LHC¨ostrand Department of Astronomy and Theoretical Physics Lund University S¨olvegatan 14A, SE-223 62 Lund, Sweden Lund
Monte Carlo sampling from the quantum state space. II
Yi-Lin Seah; Jiangwei Shang; Hui Khoon Ng; David John Nott; Berthold-Georg Englert
2015-04-27
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.
Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations
Lisal, Martin
and speed of sound for carbon dioxide (CO2) in the supercritical region, using the fluctuation method based properties of CO2 at supercritical conditions. The molecular simulation results are compared to an analytical on Monte Carlo simu- lations in the isothermalisobaric ensemble. We model CO2 as a quadrupolar two
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
Romano, Paul K. (Paul Kollath)
2013-01-01
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 ...
Batuman, O.; Kuo, Y.-W.; Palmieri, M.; Rojas, M. R.; Gilbertson, R. L.
2010-01-01
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
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
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
Vertically-tapered optical waveguide and optical spot transformer formed therefrom
Bakke, Thor; Sullivan, Charles T.
2004-07-27
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))
1995-03-01
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.
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.
2012-07-31
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.
Influence of hot spot features on the initiation characteristics of heterogeneous nitromethane
Dattelbaum, Dana M; Sheffield, Stephen A; Stahl, David B; Dattelbaum, Andrew M; Engelke, Ray
2010-01-01
To gain insights into the critical hot spot features influencing energetic materials initiation characteristics, well-defined micron-scale particles have been intentionally introduced into the homogeneous explosive nitromethane (NM). Two types of potential hot spot origins have been examined - shock impedance mismatches using solid silica beads, and porosity using hollow microballoons - as well as their sizes and inter-particle separations. Here, we present the results of several series of gas gun-driven plate impact experiments on NM/particle mixtures with well-controlled shock inputs. Detailed insights into the nature of the reactive flow during the build-up to detonation have been obtained from the response of in-situ electromagnetic gauges, and the data have been used to establish Pop-plots (run-distance-to-detonation vs. shock input pressure) for the mixtures. Comparisons of sensitization effects and energy release characteristics relative to the initial shock front between the solid and hollow beads are presented.
Eutectic structures in friction spot welding joint of aluminum alloy to copper
Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Solid-State Joining Processes, Max-Planck-Str. 1, 21502 Geesthacht (Germany)
2014-05-12
A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.
Macrophyte mapping in ten lakes of South Carolina with multispectral SPOT HRV data
Mackey, H.E. Jr.
1989-01-01
Fall and spring multispectral SPOT HRV data for 1987 and 1988 were used to evaluate the macrophyte distributions in ten freshwater reservoirs of South Carolina. The types of macrophyte and wetland communities present along the shoreline of the lakes varied depending on the age, water level fluctuations, water quality, and basin morphology. Seasonal satellite data were important for evaluation of the extent of persistent versus non-persistent macrophyte communities in the lakes. This paper contains only the view graphs of this process.
SU-E-T-73: Commissioning of a Treatment Planning System for Proton Spot Scanning
Saini, J; Kang, Y; Schultz, L; Nicewonger, D; Herrera, M; Wong, T; Bowen, S; Bloch, C
2014-06-01
Purpose: A treatment planning system (TPS) was commissioned for clinical use with a fixed beam line proton delivery system. An outline of the data collection, modeling, and verification is provided. Methods: Beam data modeling for proton spot scanning in CMS Xio TPS requires the following measurements: (i) integral depth dose curves (IDDCs); (ii) absolute dose calibration; and (iii) beam spot characteristics. The IDDCs for 18 proton energies were measured using an integrating detector in a single spot field in a water phantom. Absolute scaling of the IDDCs were performed based on ion chamber measurements in mono-energetic 10×10 cm{sup 2} fields in water. Beam spot shapes were measured in air using a flat panel scintillator detector at multiple planes. For beam model verification, more than 45 uniform dose phantom and patient plans were generated. These plans were used to measure range, point dose, and longitudinal and lateral profiles. Tolerances employed for verification are: point dose and longitudinal profiles, ±2%; range, ±1 mm; FWHM for lateral profiles, ±2 mm; and patient plan dose distribution, gamma index of >90% at 3%/3 mm criteria. Results: More than 97% of the point dose measurements out of 115 were within +/-2% with maximum deviation of 3%. 98% of the ranges measured were within 1 mm with maximum deviation of 1.4mm. The normalized depth doses were within 2% at all depths. The maximum error in FWHM of lateral profiles was found to be less than 2mm. For 5 patient plans representing different anatomic sites, a total of 38 planes for 12 beams were analyzed for gamma index with average value of 99% and minimum of 94%. Conclusions: The planning system is successfully commissioned and can be safely deployed for clinical use. Measurements of IDDCs on user beam are highly recommended instead of using standard beam IDDCs.
Molecular physics and chemistry applications of quantum Monte Carlo
Reynolds, P.J.; Barnett, R.N.; Hammond, B.L.; Lester, W.A. Jr.
1985-09-01
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.
Friction Stir Spot Welding (FSSW) of Advanced High Strength Steel (AHSS)
Santella, M. L.; Hovanski, Yuri; Pan, Tsung-Yu
2012-04-16
Friction stir spot welding (FSSW) is applied to join advanced high strength steels (AHSS): galvannealed dual phase 780 MPa steel (DP780GA), transformation induced plasticity 780 MPa steel (TRIP780), and hot-stamped boron steel (HSBS). A low-cost Si3N4 ceramic tool was developed and used for making welds in this study instead of polycrystalline cubic boron nitride (PCBN) material used in earlier studies. FSSW has the advantages of solid-state, low-temperature process, and the ability of joining dissimilar grade of steels and thicknesses. Two different tool shoulder geometries, concave with smooth surface and convex with spiral pattern, were used in the study. Welds were made by a 2-step displacement control process with weld time of 4, 6, and 10 seconds. Static tensile lap-shear strength achieved 16.4 kN for DP780GA-HSBS and 13.2kN for TRIP780-HSBS, above the spot weld strength requirements by AWS. Nugget pull-out was the failure mode of the joint. The joining mechanism was illustrated from the cross-section micrographs. Microhardness measurement showed hardening in the upper sheet steel (DP780GA or TRIP780) in the weld, but softening of HSBS in the heat-affect zone (HAZ). The study demonstrated the feasibility of making high-strength AHSS spot welds with low-cost tools.
Calculations of pair production by Monte Carlo methods
Bottcher, C.; Strayer, M.R.
1991-01-01
We describe some of the technical design issues associated with the production of particle-antiparticle pairs in very large accelerators. To answer these questions requires extensive calculation of Feynman diagrams, in effect multi-dimensional integrals, which we evaluate by Monte Carlo methods on a variety of supercomputers. We present some portable algorithms for generating random numbers on vector and parallel architecture machines. 12 refs., 14 figs.
The hybrid Monte Carlo Algorithm and the chiral transition
Gupta, R.
1987-01-01
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
2011-02-09
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.
South El Monte, 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| Open Energy Information Serbia-Enhancing Capacity forSiliciumEnergy IncAshburnham,BoundChicagoEl Monte, California:
S. J. Tingay; E. Lenc; G. Brunetti; M. Bondi
2008-10-02
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.
Stewart, Leah Beth
2013-02-22
Variation in nuclear-encoded microsatellite loci was examined among 162 spotted seatrout (Cynoscion nebulosus) sampled from three localities in the northern Gulf of Mexico (Gulf) and one locality along the southeastern ...
Wang, Wei-wei
1998-01-01
A system of finite element modeling combined with graphics. elastogram generation was used to study the detection of hard spots in beef rations. Finite element was used to model the structural deformation of beef steaks ...
Unknown
2011-09-05
The results of annealing on the residual resistance ratio (RRR) of five (5) composite aluminum cryoconductor wires and mechanical properties on fifteen (15) aluminum cryoconductor wires are presented. The independent ...
Eddings, James Richard
2009-06-02
reacts with the clay and creates a unique glaze on the surface of the piece. Wood firing is similar to soda firing except that wood is the fuel to fire the kiln and the wood ash reacts with the clay to create a glaze on the surface of the piece. Through... soda or wood ash. The pasing of flame and the addition of soda are visualy recorded on the surface of the piece. Sandblasting, like natural erosion, takes away the outer skin and reveals the subsurface and cone 04 oxidation and painting increase...
FZ2MC: A Tool for Monte Carlo Transport Code Geometry Manipulation
Hackel, B M; Nielsen Jr., D E; Procassini, R J
2009-02-25
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
Zen, Andrea; Trout, Bernhardt L.; Guidoni, Leonardo
2014-07-07
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{sup 3} ? N{sup 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.
MODELING OF HIGH SPEED FRICTION STIR SPOT WELDING USING A LAGRANGIAN FINITE ELEMENT APPROACH
Miles, Michael; Karki, U.; Woodward, C.; Hovanski, Yuri
2013-09-03
Friction stir spot welding (FSSW) has been shown to be capable of joining steels of very high strength, while also being very flexible in terms of controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding (RSW) if tool life is sufficiently high, and if machine spindle loads are sufficiently low so that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11-14 kN. Therefore, in the current work tool speeds of 3000 rpm and higher were employed, in order to generate heat more quickly and to reduce welding loads to acceptable levels. The FSSW process was modeled using a finite element approach with the Forge® software package. An updated Lagrangian scheme with explicit time integration was employed to model the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate [3]. The modeling approach can be described as two-dimensional, axisymmetric, but with an aspect of three dimensions in terms of thermal boundary conditions. Material flow was calculated from a velocity field which was two dimensional, but heat generated by friction was computed using a virtual rotational velocity component from the tool surface. An isotropic, viscoplastic Norton-Hoff law was used to model the evolution of material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures and the movement of the joint interface with reasonable accuracy for the welding of a dual phase 980 steel.
Global neutrino parameter estimation using Markov Chain Monte Carlo
Steen Hannestad
2007-10-10
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.
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)
2013-11-15
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 Carlo tests of Orbital-Free Density Functional Theory
D. I. Palade
2014-12-12
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.
Quantum Monte Carlo Simulation of Overpressurized Liquid {sup 4}He
Vranjes, L.; Boronat, J.; Casulleras, J.; Cazorla, C.
2005-09-30
A diffusion Monte Carlo simulation of superfluid {sup 4}He at zero temperature and pressures up to 275 bar is presented. Increasing the pressure beyond freezing ({approx}25 bar), the liquid enters the overpressurized phase in a metastable state. In this regime, we report results of the equation of state and the pressure dependence of the static structure factor, the condensate fraction, and the excited-state energy corresponding to the roton. Along this large pressure range, both the condensate fraction and the roton energy decrease but do not become zero. The roton energies obtained are compared with recent experimental data in the overpressurized regime.
Markov Chain Monte Carlo Method without Detailed Balance
Hidemaro Suwa; Synge Todo
2010-10-13
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.
2012-06-06
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 Tools for charged Higgs boson production
K. Kovarik
2014-12-18
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.
Multicanonical Hybrid Monte Carlo: Boosting Simulations of Compact QED
G. Arnold; Th. Lippert; K. Schilling
1998-09-21
We demonstrate that substantial progress can be achieved in the study of the phase structure of 4-dimensional compact QED by a joint use of hybrid Monte Carlo and multicanonical algorithms, through an efficient parallel implementation. This is borne out by the observation of considerable speedup of tunnelling between the metastable states, close to the phase transition, on the Wilson line. We estimate that the creation of adequate samples (with order 100 flip-flops) becomes a matter of half a year's runtime at 2 Gflops sustained performance for lattices of size up to 24^4.
Khodabakhshi, F.; Kazeminezhad, M., E-mail: mkazemi@sharif.edu; Kokabi, A.H.
2012-07-15
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.
A Look at general cavity theory through a code incorporating Monte Carlo techniques
Weyland, Mark Duffy
1989-01-01
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...
Moffitt, John Russell
1972-01-01
for finite atmospheres with phase functions ranging from isotropic to the extremely anisotropic nimbo- stratus model. The main advantages of the Monte Carlo method were illustrated. One such advantage is that parameters, such as the single scattering... as an isotropic one. Another is that a single "computer run" can produce radiance values for a large number of ground albedos for any reasonable number of detectors placed at any desired depth in the atmosphere. 2. The Monte Carlo Method Monte Carlo, in all...
Quantum Monte Carlo calculations of spectroscopic overlaps in $A \\leq 7$ nuclei
I. Brida; Steven C. Pieper; R. B. Wiringa
2011-06-15
We present Green's function Monte Carlo calculations of spectroscopic overlaps for $A \\leq 7$ nuclei. The realistic Argonne v18 two-nucleon and Illinois-7 three-nucleon interactions are used to generate the nuclear states. The overlap matrix elements are extrapolated from mixed estimates between variational Monte Carlo and Green's function Monte Carlo wave functions. The overlap functions are used to obtain spectroscopic factors and asymptotic normalization coefficients, and they can serve as an input for low-energy reaction calculations.
Control of Black Spot of Roses with Sulphur-Copper Dust.
Lyle, E. W. (Eldon W.)
1944-01-01
of the same treatment were replicated in each field. Data were taken from 5 consecutive plants in the middle row of each plot for black-spot counts and from 10 plants for weights. ?Swan Brand (conditioned) sulphur; all other mixtures made with Owl Brand....5 3.4 3.3 3.0 2.8 2.8 2.8 3.2 2.9 2.9 2.9 2.7 2.5 12 BULLETIN NO. 648, TEXAS AGRICULTURAL EXPERIMENT STATION fungicides during this season. In most cases an unconditioned 325-mesh sulphur (Owl Brand) was found as suitable for the sulphur...
Numerical studies of third-harmonic generation in laser filament in air perturbed by plasma spot
Feng Liubin; Lu Xin; Liu Xiaolong; Li Yutong; Chen Liming; Ma Jinglong; Dong Quanli; Wang Weimin; Xi Tingting; Sheng Zhengming; Zhang Jie; He Duanwei
2012-07-15
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.
Novel approach for deriving genome wide SNP analysis data from archived blood spots
Fowler, Katie E.; Reitter, Chris P.; Walling, Grant A.; Griffin, Darren K.
2012-09-13
SNP d blood spots en K Griffin1 temperature in low volumes has the advantage of apted filter papers are popular for this, with FTA ing one of the most recent. Plant material, plasmids, and transported successfully using this technology, hatmanTM cards... ://www.biomedcentral.com/1756-0500/5/503GA (before amplification, concentrations too low :A280 WGA Allele size(s) after WGA and microsatellite PCR Do direct extraction and WGA microsatellite results match? 119 ? 182 ? 119, 142 ? 121 ? 119, 139 ? 119, 149 ? 120, 140 ? 119, 137...
Hybrid NDE Method for Spot Weld Quality Evaluation | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 Delicious Rank EERE:FinancingPetroleum12,ExecutiveFinancingR Walls - BuildingofDepartmentHybirdNDE Method for Spot Weld
Four-quark energies in SU(2) lattice Monte Carlo using a tetrahedral geometry
A. M. Green; J. Lukkarinen; P. Pennanen; C. Michael; S. Furui
1994-12-05
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 model for electron degradation in methane
Bhardwaj, Anil
2015-01-01
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...
Chemical accuracy from quantum Monte Carlo for the Benzene Dimer
Azadi, Sam
2015-01-01
We report an accurate study of interactions between Benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory (DFT) using different van der Waals (vdW) functionals. In our QMC calculations, we use accurate correlated trial wave functions including three-body Jastrow factors, and backflow transformations. We consider two benzene molecules in the parallel displaced (PD) geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of -2.3(4) and -2.7(3) kcal/mol, respectively. The best estimate of the CCSD(T)/CBS limit is -2.65(2) kcal/mol [E. Miliordos et al, J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, compar...
Monte Carlo simulation of quantum Zeno effect in the brain
Danko Georgiev
2014-12-11
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.
Quantum Monte Carlo calculations of $A=9,10$ nuclei
Steven C. Pieper; K. Varga; R. B. Wiringa
2002-06-24
We report on quantum Monte Carlo calculations of the ground and low-lying excited states of $A=9,10$ nuclei using realistic Hamiltonians containing the Argonne $v_{18}$ two-nucleon potential alone or with one of several three-nucleon potentials, including Urbana IX and three of the new Illinois models. The calculations begin with correlated many-body wave functions that have an $\\alpha$-like core and multiple p-shell nucleons, $LS$-coupled to the appropriate $(J^{\\pi};T)$ quantum numbers for the state of interest. After optimization, these variational trial functions are used as input to a Green's function Monte Carlo calculation of the energy, using a constrained path algorithm. We find that the Hamiltonians that include Illinois three-nucleon potentials reproduce ten states in $^9$Li, $^9$Be, $^{10}$Be, and $^{10}$B with an rms deviation as little as 900 keV. In particular, we obtain the correct 3$^+$ ground state for $^{10}$B, whereas the Argonne $v_{18}$ alone or with Urbana IX predicts a 1$^+$ ground state. In addition, we calculate isovector and isotensor energy differences, electromagnetic moments, and one- and two-body density distributions.
Joint strength in high speed friction stir spot welded DP 980 steel
Saunders, Nathan; Miles, Michael; Hartman, Trent; Hovanski, Yuri; Hong, Sung Tae; Steel, Russell
2014-05-01
High speed friction stir spot welding was applied to 1.2 mm thick DP 980 steel sheets under different welding conditions, using PCBN tools. The range of vertical feed rates used during welding was 2.5 mm – 102 mm per minute, while the range of spindle speeds was 2500 – 6000 rpm. Extended testing was carried out for five different sets of welding conditions, until tool failure. These welding conditions resulted in vertical welding loads of 3.6 – 8.2 kN and lap shear tension failure loads of 8.9 – 11.1 kN. PCBN tools were shown, in the best case, to provide lap shear tension fracture loads at or above 9 kN for 900 spot welds, after which tool failure caused a rapid drop in joint strength. Joint strength was shown to be strongly correlated to bond area, which was measured from weld cross sections. Failure modes of the tested joints were a function of bond area and softening that occurred in the heat-affected zone.
Wear testing of friction stir spot welding tools for joining of DP 980 Steel
Ridges, Chris; Miles, Michael; Hovanski, Yuri; Peterson, Jeremy; Steel, Russell
2011-06-06
Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Several tooling materials have been evaluated in prior studies, including silicon nitride and polycrystalline cubic boron nitride (PCBN). Recently a new tool alloy has been developed, where a blend of PCBN and tungsten rhenium (W-Re) was used in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re (designated as Q60), and one with 70% PCBN and 30% W-Re (designated at Q70). The sheet material used for all wear testing was DP 980. Tool profiles were measured periodically during the testing process in order to show the progression of wear as a function of the number of spots produced. Lap shear testing was done each time a tool profile was taken in order to show the relationship between tool wear and joint strength. For the welding parameters chosen for this study the Q70 tool provided the best combination of wear resistance and joint strength.
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)
2012-02-20
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.
The Long Memory of Order Flow in the Foreign Exchange Spot Market
Gould, Martin D; Howison, Sam D
2015-01-01
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.
1989-12-31
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.
1989-01-01
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.
Possible hot spots excited by the relativistic jets of Cygnus X-3
J. Marti; D. Perez-Ramirez; J. L. Garrido; P. Luque-Escamilla; J. M. Paredes
2005-05-20
We present the results of a deep search for associated radio features in the vicinity of the microquasar Cygnus X-3. The motivation behind is to find out evidence for interaction between its relativistic jets and the surrounding interstellar medium, which could eventually allow us to perform calorimetry of the total energy released by this microquasar during its flaring lifetime. Remarkably, two radio sources with mJy emission level at centimeter wavelengths have been detected in excellent alignment with the position angle of the inner radio jets. We propose that these objects could be the hot spots where the relativitic outflow collides with the ambient gas in analogy with Fanaroff-Riley II radio galaxies. These candidate hot spots are within a few arc-minutes of Cygnus X-3 and, if physically related, the full linear extent of the jet would reach tens of parsecs. We discuss here the evidence currently available to support this hypothesis based on both archival data and our own observations.
Pappu, Hanu R.
Report of Iris yellow spot virus on Onion (Allium cepa) in Texas. M. E. Miller and R. R. Saldana, Texas A
Brachytherapy structural shielding calculations using Monte Carlo generated, monoenergetic data
Zourari, K.; Peppa, V.; Papagiannis, P.; Ballester, Facundo; Siebert, Frank-André
2014-04-15
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.
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
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
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
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
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
THEORETICAL STUDY OF MULTILAYER LUMINESCENT SOLAR CONCENTRATORS USING A MONTE CARLO APPROACH
cost is subject to highly volatile market. Solar concentrators usually make use of mobile mirrors ableTHEORETICAL STUDY OF MULTILAYER LUMINESCENT SOLAR CONCENTRATORS USING A MONTE CARLO APPROACH a theoretical study of luminescent solar concentrators (LSCs) based on a ray-tracing technique with a Monte
Communication: Monte Carlo calculation of the exchange energy Roi Baer and Daniel Neuhauser
Baer, Roi
Communication: Monte Carlo calculation of the exchange energy Roi Baer and Daniel Neuhauser subject to AIP license or copyright; see http://jcp.aip.org/about/rights_and_permissions #12;THE JOURNAL OF CHEMICAL PHYSICS 137, 051103 (2012) Communication: Monte Carlo calculation of the exchange energy Roi Baer1
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
Carlo Mike Giles (Oxford) Monte Carlo methods May 3031, 2013 2 / 33 SDEs in Finance In computational finance, stochastic differential equations are used to model the behaviour of stocks interest rates exchange rates weather electricity/gas demand crude oil prices . . . Mike Giles (Oxford) Monte Carlo
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
Carlo Mike Giles (Oxford) Monte Carlo methods May 3031, 2013 2 / 33 #12;SDEs in Finance In computational finance, stochastic differential equations are used to model the behaviour of stocks interest rates exchange rates weather electricity/gas demand crude oil prices . . . Mike Giles (Oxford) Monte
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
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
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
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
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
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)
2014-12-31
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)
Monte Carlo Simulation of Dense Polymer Melts Using Event Chain Algorithms
Tobias Alexander Kampmann; Horst-Holger Boltz; Jan Kierfeld
2015-07-23
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.
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.
2013-09-02
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.
Improved version of the PHOBOS Glauber Monte Carlo
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Loizides, C.; Nagle, J.; Steinberg, P.
2015-09-01
“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
The Quantum Energy Density: Improved Efficiency for Quantum Monte Carlo
Krogel, Jaron T; Kim, Jeongnim; Ceperley, David M
2013-01-01
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
2014-01-01
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...
Quantum Monte Carlo Calculations of $A\\leq6$ Nuclei
B. S. Pudliner; V. R. Pandharipande; J. Carlson; R. B. Wiringa
1995-02-13
The energies of $^{3}H$, $^{3}He$, and $^{4}He$ ground states, the ${\\frac{3}{2}}^{-}$ and ${\\frac{1}{2}}^{-}$ scattering states of $^{5}He$, the ground states of $^{6}He$, $^{6}Li$, and $^{6}Be$ and the $3^{+}$ and $0^{+}$ excited states of $^{6}Li$ have been accurately calculated with the Green's function Monte Carlo method using realistic models of two- and three-nucleon interactions. The splitting of the $A=3$ isospin $T=\\frac{1}{2}$ and $A=6$ isospin $T=1$, $J^{\\pi} = 0^{+}$ multiplets is also studied. The observed energies and radii are generally well reproduced, however, some definite differences between theory and experiment can be identified.
Quantum Monte Carlo simulation of spin-polarized H
Markic, L. Vranjes; Boronat, J.; Casulleras, J.
2007-02-01
The ground-state properties of spin polarized hydrogen H{down_arrow} are obtained by means of diffusion Monte Carlo calculations. Using the most accurate to date ab initio H{down_arrow}-H{down_arrow} interatomic potential we have studied its gas phase, from the very dilute regime until densities above its freezing point. At very small densities, the equation of state of the gas is very well described in terms of the gas parameter {rho}a{sup 3}, with a the s-wave scattering length. The solid phase has also been studied up to high pressures. The gas-solid phase transition occurs at a pressure of 173 bar, a much higher value than suggested by previous approximate descriptions.
Improving multivariate Horner schemes with Monte Carlo tree search
J. Kuipers; J. A. M. Vermaseren; A. Plaat; H. J. van den Herik
2012-07-30
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.
Lifting -- A Nonreversible Markov Chain Monte Carlo Algorithm
Vucelja, Marija
2015-01-01
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...
SU-E-T-188: Film Dosimetry Verification of Monte Carlo Generated Electron Treatment Plans
Enright, S; Asprinio, A; Lu, L
2014-06-01
Purpose: The purpose of this study was to compare dose distributions from film measurements to Monte Carlo generated electron treatment plans. Irradiation with electrons offers the advantages of dose uniformity in the target volume and of minimizing the dose to deeper healthy tissue. Using the Monte Carlo algorithm will improve dose accuracy in regions with heterogeneities and irregular surfaces. Methods: Dose distributions from GafChromic{sup ™} EBT3 films were compared to dose distributions from the Electron Monte Carlo algorithm in the Eclipse{sup ™} radiotherapy treatment planning system. These measurements were obtained for 6MeV, 9MeV and 12MeV electrons at two depths. All phantoms studied were imported into Eclipse by CT scan. A 1 cm thick solid water template with holes for bonelike and lung-like plugs was used. Different configurations were used with the different plugs inserted into the holes. Configurations with solid-water plugs stacked on top of one another were also used to create an irregular surface. Results: The dose distributions measured from the film agreed with those from the Electron Monte Carlo treatment plan. Accuracy of Electron Monte Carlo algorithm was also compared to that of Pencil Beam. Dose distributions from Monte Carlo had much higher pass rates than distributions from Pencil Beam when compared to the film. The pass rate for Monte Carlo was in the 80%–99% range, where the pass rate for Pencil Beam was as low as 10.76%. Conclusion: The dose distribution from Monte Carlo agreed with the measured dose from the film. When compared to the Pencil Beam algorithm, pass rates for Monte Carlo were much higher. Monte Carlo should be used over Pencil Beam for regions with heterogeneities and irregular surfaces.
Chromospheric activity of ROSAT discovered weaklined T Tauri stars D. Montes 1;2 , L.W. Ramsey 1
Complutense de Madrid, Universidad
Chromospheric activity of ROSAT discovered weaklined T Tauri stars D. Montes 1;2 , L.W. Ramsey 1 1 are available (see Feigelson et al. 1994; Welty 1995; Welty & Ramsey 1995, 1998; Poncet et al. 1998; Montes
Koh, Wonshill
2013-02-22
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...
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)
2014-04-28
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.
Impact of tool wear on joint strength in friction stir spot welding of DP 980 steel
Miles, Michael; Ridges, Chris; Hovanski, Yuri; Peterson, Jeremy; Santella, M. L.; Steel, Russel
2011-09-14
Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Recently a new tool alloy has been developed, using a blend of PCBN and tungsten rhenium (W-Re) in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re, and one with 70% PCBN and 30% W-Re. The sheet material used for all wear testing was 1.4 mm DP 980. Lap shear testing was used to show the relationship between tool wear and joint strength. The Q70 tool provided the best combination of wear resistance and joint strength.
Electric rate that shifts hourly may foretell spot-market kWh
Springer, N.
1985-11-25
Four California industrial plants have cut their electricity bills up to 16% by shifting from the traditional time-of-use rates to an experimental real-time program (RTP) that varies prices hourly. The users receive a price schedule reflecting changing generating costs one day in advance to encourage them to increase power consumption during the cheapest time periods. Savings during the pilot program range between $11,000 and $32,000 per customer. The hourly cost breakdown encourages consumption during the night and early morning. The signalling system could be expanded to cogenerators and independent small power producers. If an electricity spot market develops, forecasters think a place on the stock exchanges for future-delivery contracts could develop in the future.
Ultrasonic Spot Welding of AZ31B to Galvanized Mild Steel
Pan, Dr. Tsung-Yu; Franklin, Teresa; Pan, Professor Jwo; Brown, Elliot; Santella, Michael L
2010-01-01
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.
Deflected Jets or Hot Spots? Conical Correlations of Hard Trigger Particles
Barbara Betz
2010-12-20
The double-peak structure observed in soft-hard dihadron correlations was recently studied intensively in order to learn more about the jet-induced medium excitation in ultrarelativistic heavy-ion collisions. Experimental data shows that the double-peak structure obtained for soft trigger particles coalesces into one peak for harder trigger particles. We demonstrate that this effect occurs when averaging over many jet events in a transversally expanding background, while a hot spot scenario always leads to two distinct peaks. This suggests to study soft-hard correlations induced by heavy-flavor jets with those generated by light-flavor jets at RHIC and LHC in order to really disentangle medium effects from jets.
Automatic Generation of a JET 3D Neutronics Model from CAD Geometry Data for Monte Carlo Calculations
Heat-affected zone liquation crack on resistance spot welded TWIP steels
Saha, Dulal Chandra [Department of Advanced Materials Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Chang, InSung [Automotive Production Development Division, Hyundai Motor Company (Korea, Republic of); Park, Yeong-Do, E-mail: ypark@deu.ac.kr [Department of Advanced Materials Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)
2014-07-01
In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.
Landsat and SPOT data for oil exploration in North-Western China
Nishidai, Takashi
1996-07-01
Satellite remote sensing technology has been employed by Japex to provide information related to oil exploration programs for many years. Since the beginning of the 1980`s, regional geological interpretation through to advanced studies using satellite imagery with high spectral and spatial resolutions (such as Landsat TM and SPOT HRV), have been carried out, for both exploration programs and for scientific research. Advanced techniques (including analysis of airborne hyper-multispectral imaging sensor data) as well as conventional photogeological techniques were used throughout these programs. The first program using remote sensing technology in China focused on the Tarim Basin, Xinjiang Uygur Autonomous Region, and was carried out using Landsat MSS data. Landsat MSS imagery allows us to gain useful preliminary geological information about an area of interest, prior to field studies. About 90 Landsat scenes cover the entire Xinjiang Uygru Autonomous Region, this allowed us to give comprehensive overviews of 3 hydrocarbon-bearing basins (Tarim, Junggar, and Turpan-Hami) in NW China. The overviews were based on the interpretations and assessments of the satellite imagery and on a synthesis of the most up-to-date accessible geological and geophysical data as well as some field works. Pairs of stereoscopic SPOT HRV images were used to generate digital elevation data with a 40 in grid cover for part of the Tarim Basin. Topographic contour maps, created from this digital elevation data, at scales of 1:250,000 and 1:100,000 with contour intervals of 100 m and 50 m, allowed us to make precise geological interpretation, and to carry out swift and efficient geological field work. Satellite imagery was also utilized to make medium scale to large scale image maps, not only to interpret geological features but also to support field workers and seismic survey field operations.
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
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
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
Many anglers now use the practice of Catch and Release to help ensure that their favorite fishing spot has plenty of fish to catch. Catch and Release fishing is a great way for anglers to enjoy their sport, and still maintain adequate stocks of fish and a healthy ecosystem for future anglers. Some
Post-Harvest Control of Two-Spotted Spider Mites in Nikki Rothwell, District Fruit IPM Educator
red mite (ERM), ERM tends to be rounded and not quite as long as TSSM. TSSM also have fewer "bristles" than ERM and obvious black spots. ERM are often red, but color differences are not always as dramatic bronzing caused by TSSM is often more gray in color than bronzing by ERM. Although bronzing presents
Strategic Behavior in Spot Markets for Electricity when Load is Stochastic T.D. Mount Department of market power to raise prices above competitive levels in the UK market for electricity has been discussed in an electricity market. In spite of this abundant evidence, regulators in the USA have been relatively unconcerned
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
White, Douglas R.
of an efficient and stable wholesale power market. If the retail market were to achieve a comparable efficiencyMBS 97-07 Open Transmission and Spot Markets for Power: Models of Power and Transmission Pricing markets for electric power by requiring utilities to open their transmission systems to wholesale power
Complete Monte Carlo Simulation of Neutron Scattering Experiments
Drosg, M.
2011-12-13
In the far past, it was not possible to accurately correct for the finite geometry and the finite sample size of a neutron scattering set-up. The limited calculation power of the ancient computers as well as the lack of powerful Monte Carlo codes and the limitation in the data base available then prevented a complete simulation of the actual experiment. Using e.g. the Monte Carlo neutron transport code MCNPX [1], neutron scattering experiments can be simulated almost completely with a high degree of precision using a modern PC, which has a computing power that is ten thousand times that of a super computer of the early 1970s. Thus, (better) corrections can also be obtained easily for previous published data provided that these experiments are sufficiently well documented. Better knowledge of reference data (e.g. atomic mass, relativistic correction, and monitor cross sections) further contributes to data improvement. Elastic neutron scattering experiments from liquid samples of the helium isotopes performed around 1970 at LANL happen to be very well documented. Considering that the cryogenic targets are expensive and complicated, it is certainly worthwhile to improve these data by correcting them using this comparatively straightforward method. As two thirds of all differential scattering cross section data of {sup 3}He(n,n){sup 3}He are connected to the LANL data, it became necessary to correct the dependent data measured in Karlsruhe, Germany, as well. A thorough simulation of both the LANL experiments and the Karlsruhe experiment is presented, starting from the neutron production, followed by the interaction in the air, the interaction with the cryostat structure, and finally the scattering medium itself. In addition, scattering from the hydrogen reference sample was simulated. For the LANL data, the multiple scattering corrections are smaller by a factor of five at least, making this work relevant. Even more important are the corrections to the Karlsruhe data due to the inclusion of the missing outgoing self-attenuation that amounts to up to 15%.
A study of the contrast of a submerged disc using Monte Carlo techniques
Hagan, Donald Frank
1980-01-01
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...
Auxiliary Field Diffusion Monte Carlo calculation of nuclei with A<40 with tensor interactions
S. Gandolfi; F. Pederiva; S. Fantoni; K. E. Schmidt
2007-04-13
We calculate the ground-state energy of 4He, 8He, 16O, and 40Ca using the auxiliary field diffusion Monte Carlo method in the fixed phase approximation and the Argonne v6' interaction which includes a tensor force. Comparison of our light nuclei results to those of Green's function Monte Carlo calculations shows the accuracy of our method for both open and closed shell nuclei. We also apply it to 16O and 40Ca to show that quantum Monte Carlo methods are now applicable to larger nuclei.
Perfetti, Christopher M [ORNL; Rearden, Bradley T [ORNL
2014-01-01
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.
Monte Carlo simulation of the terrestrial hydrogen exosphere
Hodges, R.R. Jr. [Univ. of Texas, Dallas, TX (United States)
1994-12-01
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.
Nuclear Force from Monte Carlo Simulations of Lattice Quantum Chromodynamics
S. Aoki; T. Hatsuda; N. Ishii
2008-10-24
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.
Performance of three-photon PET imaging: Monte Carlo simulations
Kacperski, K; Kacperski, Krzysztof; Spyrou, Nicholas M.
2005-01-01
We have recently introduced the idea of making use of three-photon positron annihilations in positron emission tomography. In this paper the basic characteristics of the three-gamma imaging in PET are studied by means of Monte Carlo simulations and analytical computations. Two typical configurations of human and small animal scanners are considered. Three-photon imaging requires high energy resolution detectors. Parameters currently attainable by CdZnTe semiconductor detectors, the technology of choice for the future development of radiation imaging, are assumed. Spatial resolution is calculated as a function of detector energy resolution and size, position in the field of view, scanner size, and the energies of the three gamma annihilation photons. Possible ways to improve the spatial resolution obtained for nominal parameters: 1.5 cm and 3.2 mm FWHM for human and small animal scanners, respectively, are indicated. Counting rates of true and random three-photon events for typical human and small animal scann...
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
White, Alexander J.; Gorshkov, Vyacheslav N.; Tretiak, Sergei; Mozyrsky, Dmitry
2015-07-07
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficientmore »as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems.« less
High order Chin actions in path integral Monte Carlo
Sakkos, K.; Casulleras, J.; Boronat, J.
2009-05-28
High order actions proposed by Chin have been used for the first time in path integral Monte Carlo simulations. Contrary to the Takahashi-Imada action, which is accurate to the fourth order only for the trace, the Chin action is fully fourth order, with the additional advantage that the leading fourth-order error coefficients are finely tunable. By optimizing two free parameters entering in the new action, we show that the time step error dependence achieved is best fitted with a sixth order law. The computational effort per bead is increased but the total number of beads is greatly reduced and the efficiency improvement with respect to the primitive approximation is approximately a factor of 10. The Chin action is tested in a one-dimensional harmonic oscillator, a H{sub 2} drop, and bulk liquid {sup 4}He. In all cases a sixth-order law is obtained with values of the number of beads that compare well with the pair action approximation in the stringent test of superfluid {sup 4}He.
Monte Carlo sampling from the quantum state space. I
Jiangwei Shang; Yi-Lin Seah; Hui Khoon Ng; David John Nott; Berthold-Georg Englert
2015-04-27
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.
Ensemble bayesian model averaging using markov chain Monte Carlo sampling
Vrugt, Jasper A; Diks, Cees G H; Clark, Martyn P
2008-01-01
Bayesian model averaging (BMA) has recently been proposed as a statistical method to calibrate forecast ensembles from numerical weather models. Successful implementation of BMA however, requires accurate estimates of the weights and variances of the individual competing models in the ensemble. In their seminal paper (Raftery etal. Mon Weather Rev 133: 1155-1174, 2(05)) has recommended the Expectation-Maximization (EM) algorithm for BMA model training, even though global convergence of this algorithm cannot be guaranteed. In this paper, we compare the performance of the EM algorithm and the recently developed Differential Evolution Adaptive Metropolis (DREAM) Markov Chain Monte Carlo (MCMC) algorithm for estimating the BMA weights and variances. Simulation experiments using 48-hour ensemble data of surface temperature and multi-model stream-flow forecasts show that both methods produce similar results, and that their performance is unaffected by the length of the training data set. However, MCMC simulation with DREAM is capable of efficiently handling a wide variety of BMA predictive distributions, and provides useful information about the uncertainty associated with the estimated BMA weights and variances.
Monte Carlo Simulations of Lattice Models for Single Polymer Systems
Hsiao-Ping Hsu
2015-03-03
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 $N \\sim {\\cal O}(10^4)$. 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 $\\sqrt{10}$, we investigate the conformations of polymer chains described by self-avoiding walks (SAWs) on the simple cubic lattice, and by random walks (RWs) and non-reversible random walks (NRRWs) in the absence of excluded volume (EV) 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
2011-07-06
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.
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
2014-04-18
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
2014-04-23
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...
Improvements and applications of the Uniform Fission Site method in Monte Carlo
Hunter, Jessica Lynn
2014-01-01
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 ...
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)
2012-07-01
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)
Walsh, Jonathan A. (Jonathan Alan)
2014-01-01
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 ...
Pasciak, Alexander Samuel
2007-04-25
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 ...
Wang, Li-Fang, Ph. D. Massachusetts Institute of Technology
2007-01-01
In this thesis research, a coherent scattering model for microwave remote sensing of vegetation canopy is developed on the basis of Monte Carlo simulations. An accurate model of vegetation structure is essential for the ...
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
Matrix Elements with Vetoes in the CASCADE Monte Carlo Event Generator
Michal Deak; Francesco Hautmann; Hannes Jung; Krzysztof Kutak
2012-06-08
We illustrate a study based on a veto technique to match parton showers and matrix elements in the Cascade Monte Carlo event generator, and present a numerical application to gluon matrix elements for jet production.
Shifting Preferences and Time-Varying Parameters in Demand Analysis: A Monte Carlo Study
Kanyama, Isaac Kalonda
2011-05-31
Using Monte Carlo experiments, I address two issues in demand analysis. The first relates to the performance of local flexible functional forms in recovering the time-varying elasticities of a true model, and in correctly identifying goods...
Monte Carlo and thermal hydraulic coupling using low-order nonlinear diffusion acceleration
Herman, Bryan R. (Bryan Robert)
2014-01-01
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 ...
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
Xu, Sheng, S.M. Massachusetts Institute of Technology
2013-01-01
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 ...
Protein folding and phylogenetic tree reconstruction using stochastic approximation Monte Carlo
Cheon, Sooyoung
2007-09-17
Recently, the stochastic approximation Monte Carlo algorithm has been proposed by Liang et al. (2005) as a general-purpose stochastic optimization and simulation algorithm. An annealing version of this algorithm was developed for real small protein...
Northum, Jeremy Dell
2011-08-08
The purpose of this study was to determine how well the Monte Carlo transport code FLUKA can simulate a tissue-equivalent proportional counter (TEPC) and produce the expected delta ray events when exposed to high energy ...
Quadratic Diffusion Monte-Carlo Algorithms for Solving Atomic Many-Body Problems
Chin, Siu A.
1990-01-01
The diffusion Monte Carlo algorithm with and without importance sampling is analyzed in terms of the algorithm's underlying transfer matrix. The crucial role played by the Langevin algorithm in the importance-sampling ...
Fourth-order diffusion Monte Carlo algorithms for solving quantum many-body problems
Forbert, HA; Chin, Siu A.
2001-01-01
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 ...
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
Radiative transfer in the earth's atmosphere-ocean system using Monte Carlo techniques
Bradley, Paul Andrew
1987-01-01
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...
Fessler, Jeffrey A.
, bibli- ography, etc., are within this material only unless specified otherwise. I. ROBUSTNESS OF MONTE
High explosive spot test analyses of samples from Operable Unit (OU) 1111
McRae, D.; Haywood, W.; Powell, J.; Harris, B.
1995-01-01
A preliminary evaluation has been completed of environmental contaminants at selected sites within the Group DX-10 (formally Group M-7) area. Soil samples taken from specific locations at this detonator facility were analyzed for harmful metals and screened for explosives. A sanitary outflow, a burn pit, a pentaerythritol tetranitrate (PETN) production outflow field, an active firing chamber, an inactive firing chamber, and a leach field were sampled. Energy dispersive x-ray fluorescence (EDXRF) was used to obtain semi-quantitative concentrations of metals in the soil. Two field spot-test kits for explosives were used to assess the presence of energetic materials in the soil and in items found at the areas tested. PETN is the major explosive in detonators manufactured and destroyed at Los Alamos. No measurable amounts of PETN or other explosives were detected in the soil, but items taken from the burn area and a high-energy explosive (HE)/chemical sump were contaminated. The concentrations of lead, mercury, and uranium are given.
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.
2009-01-01
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
Direct Simulations of Homogeneous Bubble Nucleation: Agreement with CNT and no Local Hot Spots
Jürg Diemand; Raymond Angélil; Kyoko K. Tanaka; Hidekazu Tanaka
2014-10-24
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.
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.
2009-01-01
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
PyMercury: Interactive Python for the Mercury Monte Carlo Particle Transport Code
Iandola, F N; O'Brien, M J; Procassini, R J
2010-11-29
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.
Quantum Monte Carlo methods and lithium cluster properties
Owen, R.K.
1990-12-01
Properties of small lithium clusters with sizes ranging from n = 1 to 5 atoms were investigated using quantum Monte Carlo (QMC) methods. Cluster geometries were found from complete active space self consistent field (CASSCF) calculations. A detailed development of the QMC method leading to the variational QMC (V-QMC) and diffusion QMC (D-QMC) methods is shown. The many-body aspect of electron correlation is introduced into the QMC importance sampling electron-electron correlation functions by using density dependent parameters, and are shown to increase the amount of correlation energy obtained in V-QMC calculations. A detailed analysis of D-QMC time-step bias is made and is found to be at least linear with respect to the time-step. The D-QMC calculations determined the lithium cluster ionization potentials to be 0.1982(14) [0.1981], 0.1895(9) [0.1874(4)], 0.1530(34) [0.1599(73)], 0.1664(37) [0.1724(110)], 0.1613(43) [0.1675(110)] Hartrees for lithium clusters n = 1 through 5, respectively; in good agreement with experimental results shown in the brackets. Also, the binding energies per atom was computed to be 0.0177(8) [0.0203(12)], 0.0188(10) [0.0220(21)], 0.0247(8) [0.0310(12)], 0.0253(8) [0.0351(8)] Hartrees for lithium clusters n = 2 through 5, respectively. The lithium cluster one-electron density is shown to have charge concentrations corresponding to nonnuclear attractors. The overall shape of the electronic charge density also bears a remarkable similarity with the anisotropic harmonic oscillator model shape for the given number of valence electrons.
Quantum Monte Carlo methods and lithium cluster properties. [Atomic clusters
Owen, R.K.
1990-12-01
Properties of small lithium clusters with sizes ranging from n = 1 to 5 atoms were investigated using quantum Monte Carlo (QMC) methods. Cluster geometries were found from complete active space self consistent field (CASSCF) calculations. A detailed development of the QMC method leading to the variational QMC (V-QMC) and diffusion QMC (D-QMC) methods is shown. The many-body aspect of electron correlation is introduced into the QMC importance sampling electron-electron correlation functions by using density dependent parameters, and are shown to increase the amount of correlation energy obtained in V-QMC calculations. A detailed analysis of D-QMC time-step bias is made and is found to be at least linear with respect to the time-step. The D-QMC calculations determined the lithium cluster ionization potentials to be 0.1982(14) (0.1981), 0.1895(9) (0.1874(4)), 0.1530(34) (0.1599(73)), 0.1664(37) (0.1724(110)), 0.1613(43) (0.1675(110)) Hartrees for lithium clusters n = 1 through 5, respectively; in good agreement with experimental results shown in the brackets. Also, the binding energies per atom was computed to be 0.0177(8) (0.0203(12)), 0.0188(10) (0.0220(21)), 0.0247(8) (0.0310(12)), 0.0253(8) (0.0351(8)) Hartrees for lithium clusters n = 2 through 5, respectively. The lithium cluster one-electron density is shown to have charge concentrations corresponding to nonnuclear attractors. The overall shape of the electronic charge density also bears a remarkable similarity with the anisotropic harmonic oscillator model shape for the given number of valence electrons.
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)
2015-01-01
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.
Hutto Fretty, Corneil Kimberly
2014-05-06
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...
Final Report: 06-LW-013, Nuclear Physics the Monte Carlo Way
Ormand, W E
2009-03-01
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.
Marin Herrera, Mario A.
2010-08-11
Four experimental classifications of coastal mangroves in Belize were developed using Definiens software using various combinations of SPOT multispectral data and ALOS L-band PALSAR data combined with digital surface models ...
CROSS-WORD SUB-WORD UNITS FOR LOW-RESOURCE KEYWORD SPOTTING William Hartmann, Lori Lamel, and Jean-Luc Gauvain Spoken Language Processing Group, LIMSI-CNRS 91403 Orsay, France {hartmann, lamel, gauvain
Howard, M; Beltran, C; Herman, M
2014-06-01
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.
Fission matrix-based Monte Carlo criticality analysis of fuel storage pools
Farlotti, M.; Larsen, E. W.
2013-07-01
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)
Jamieson, Bruce
International Snow Science Workshop Grenoble Chamonix Mont-Blanc 2013 Stability tests the avalanche danger, professionals and experienced recreationists rely on observations from snow profiles
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
2009-10-01
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.
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)
2013-09-15
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.
A Proposal for a Standard Interface Between Monte Carlo Tools And One-Loop Programs
Binoth, T.; Boudjema, F.; Dissertori, G.; Lazopoulos, A.; Denner, A.; Dittmaier, S.; Frederix, R.; Greiner, N.; Hoeche, Stefan; Giele, W.; Skands, P.; Winter, J.; Gleisberg, T.; Archibald, J.; Heinrich, G.; Krauss, F.; Maitre, D.; Huber, M.; Huston, J.; Kauer, N.; 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.
2011-11-11
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.
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)
1999-01-01
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.
1999-02-09
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
2012-12-24
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.
Monte Carlo techniques of simulation applied to a single item inventory system
Aldred, William Murray
1965-01-01
of MASTER OF SCIENCE August 1965 Major SubJect: Computer Science MONTE CARLO TECHNIQUES OF SIMULATION APPLIED TO A SINGLE ITEM INVENTORY SYSTEM A Thesis By WILLIAM MURRAY ALDRED, JR. Approved as to style and content by: (Chairman of Committee (Head... as it operates. Now that the basic principles and requirements of a simulati. on study have been outlined, it seems appropriate to discuss one of the better methods of reducing the data to a form suitable for simulation by a computer. Monte Carlo Technique...
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
2011-01-01
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.
Spin-orbit induced backflow in neutron matter with auxiliary field diffusion Monte Carlo
L. Brualla; S. Fantoni; A. Sarsa; K. E Schmidt; S. A. Vitiello
2003-04-14
The energy per particle of zero-temperature neutron matter is investigated, with particular emphasis on the role of the $\\vec L\\cdot\\vec S$ interaction. An analysis of the importance of explicit spin--orbit correlations in the description of the system is carried out by the auxiliary field diffusion Monte Carlo method. The improved nodal structure of the guiding function, constructed by explicitly considering these correlations, lowers the energy. The proposed spin--backflow orbitals can conveniently be used also in Green's Function Monte Carlo calculations of light nuclei.
Miles, Michael; Karki, U.; Hovanski, Yuri
2014-10-01
Friction-stir spot welding (FSSW) has been shown to be capable of joining advanced high-strength steel, with its flexibility in controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding if tool life is sufficiently high, and if machine spindle loads are sufficiently low that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8 kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11–14 kN. Therefore, in the current work, tool speeds of 5000 rpm were employed to generate heat more quickly and to reduce welding loads to acceptable levels. Si3N4 tools were used for the welding experiments on 1.2-mm DP 980 steel. The FSSW process was modeled with a finite element approach using the Forge* software. An updated Lagrangian scheme with explicit time integration was employed to predict the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate. Material flow was calculated from a velocity field that is two-dimensional, but heat generated by friction was computed by a novel approach, where the rotational velocity component imparted to the sheet by the tool surface was included in the thermal boundary conditions. An isotropic, viscoplastic Norton-Hoff law was used to compute the material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures to within percent, and the position of the joint interface to within 10 percent, of the experimental results.
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.
2014-10-07
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
Lillaney, Prasheel; Shin, Mihye; Conolly, Steven M.; Fahrig, Rebecca
2012-09-15
Purpose: Combining x-ray fluoroscopy and MR imaging systems for guidance of interventional procedures has become more commonplace. By designing an x-ray tube that is immune to the magnetic fields outside of the MR bore, the two systems can be placed in close proximity to each other. A major obstacle to robust x-ray tube design is correcting for the effects of the magnetic fields on the x-ray tube focal spot. A potential solution is to design active shielding that locally cancels the magnetic fields near the focal spot. Methods: An iterative optimization algorithm is implemented to design resistive active shielding coils that will be placed outside the x-ray tube insert. The optimization procedure attempts to minimize the power consumption of the shielding coils while satisfying magnetic field homogeneity constraints. The algorithm is composed of a linear programming step and a nonlinear programming step that are interleaved with each other. The coil results are verified using a finite element space charge simulation of the electron beam inside the x-ray tube. To alleviate heating concerns an optimized coil solution is derived that includes a neodymium permanent magnet. Any demagnetization of the permanent magnet is calculated prior to solving for the optimized coils. The temperature dynamics of the coil solutions are calculated using a lumped parameter model, which is used to estimate operation times of the coils before temperature failure. Results: For a magnetic field strength of 88 mT, the algorithm solves for coils that consume 588 A/cm{sup 2}. This specific coil geometry can operate for 15 min continuously before reaching temperature failure. By including a neodymium magnet in the design the current density drops to 337 A/cm{sup 2}, which increases the operation time to 59 min. Space charge simulations verify that the coil designs are effective, but for oblique x-ray tube geometries there is still distortion of the focal spot shape along with deflections of approximately 3 mm in the radial and circumferential directions on the anode. Conclusions: Active shielding is an attractive solution for correcting the effects of magnetic fields on the x-ray focal spot. If extremely long fluoroscopic exposure times are required, longer operation times can be achieved by including a permanent magnet with the active shielding design.
NONE
1998-01-01
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.
Chung, Kiwhan
1996-01-01
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...
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
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
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
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
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
Introduction to Markov Chain Monte Carlo Simulations and their Statistical Analysis
Bernd A. Berg
2004-10-19
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.
Calculating Risk of Cost Using Monte Carlo Simulations with Fuzzy Parameters in Civil Engineering
Pownuk, Andrzej
of project, contractor's lack experience, poor labor productivity, project changes [10, 6]. The risk of costCalculating Risk of Cost Using Monte Carlo Simulations with Fuzzy Parameters in Civil Engineering@zeus.polsl.gliwice.pl, http://zeus.polsl.gliwice.pl/ pownuk August 1, 2004 Abstract. Risk is a part of almost all civil
Use of single scatter electron monte carlo transport for medical radiation sciences
Svatos, Michelle M. (Oakland, CA)
2001-01-01
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.
Assessing fire risk using Monte Carlo simulations of fire spread Yohay Carmel a,
Assessing fire risk using Monte Carlo simulations of fire spread Yohay Carmel a, *, Shlomit Paz b of Haifa, Haifa, Israel 1. Introduction Fires are a major source of forest destruction in the Mediterranean., 2000). Mediterranean fires are largely determined by climatic conditions; long, dry summers with high
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
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
Monte-Carlo simulations of polymer crystallization in dilute solution C.-M. Chena)
Chen, Chi-Ming
carbon atoms, and we also investigate chain folding of very long polymers. For monodisperse flexibleMonte-Carlo simulations of polymer crystallization in dilute solution C.-M. Chena) and Paul G Received 7 July 1997; accepted 8 December 1997 Polymer crystallization in dilute solution is studied
Monte Carlo Tree Search for Simulated Car Racing Jacob Fischer1
Togelius, Julian
Monte 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 algorithm. Similarly, simulated car racing presents interesting challenges to artificial intelligence (AI
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
Alcouffe, R.E.
1985-01-01
A difficult class of problems for the discrete-ordinates neutral particle transport method is to accurately compute the flux due to a spatially localized source. Because the transport equation is solved for discrete directions, the so-called ray effect causes the flux at space points far from the source to be inaccurate. Thus, in general, discrete ordinates would not be the method of choice to solve such problems. It is better suited for calculating problems with significant scattering. The Monte Carlo method is suited to localized source problems, particularly if the amount of collisional interactions in minimal. However, if there are many scattering collisions and the flux at all space points is desired, then the Monte Carlo method becomes expensive. To take advantage of the attributes of both approaches, we have devised a first collision source method to combine the Monte Carlo and discrete-ordinates solutions. That is, particles are tracked from the source to their first scattering collision and tallied to produce a source for the discrete-ordinates calculation. A scattered flux is then computed by discrete ordinates, and the total flux is the sum of the Monte Carlo and discrete ordinates calculated fluxes. In this paper, we present calculational results using the MCNP and TWODANT codes for selected two-dimensional problems that show the effectiveness of this method.
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
Monte Carlo simulation of liquid bridge rupture: Application to lung physiology Adriano M. Alencar,1
Alencar, Adriano Mesquita
Monte Carlo simulation of liquid bridge rupture: Application to lung physiology Adriano M. Alencar of certain lung diseases, the surface properties and the amount of fluids coating the airways changes of similar bridges that exist in diseased lungs. DOI: 10.1103/PhysRevE.74.026311 PACS number s : 47.90 a, 04
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
10,000 STANDARD SOLAR MODELS: A MONTE CARLO SIMULATION John N. Bahcall1
Bahcall, John
if a given prediction from solar models agrees or disagrees with a measured value. We proceed by constructing quanti- ties to describe the statistical significance of comparisons between solar model predictions systematic attempt to use Monte Carlo simula- tions to determine the uncertainties in solar model predictions
10,000 STANDARD SOLAR MODELS: A MONTE CARLO SIMULATION John N. Bahcall 1
Bahcall, John
if a given prediction from solar models agrees or disagrees with a measured value. We proceed by constructing quanti ties to describe the statistical significance of comparisons between solar model predictions systematic attempt to use Monte Carlo simula tions to determine the uncertainties in solar model predictions
Jamieson, Bruce
International Snow Science Workshop Grenoble Chamonix Mont-Blanc - 2013 Weather preceding rapid mass loading via precipitation or wind transported snow or from snowpack warming by air. INTRODUCTION Weather is one of the most important factors in snow slab avalanche formation, as it creates
Monte Carlo Methods for Equilibrium and Nonequilibrium Problems in Interfacial Electrochemistry
Gregory Brown; Per Arne Rikvold; S. J. Mitchell; M. A. Novotny
1998-05-11
We present a tutorial discussion of Monte Carlo methods for equilibrium and nonequilibrium problems in interfacial electrochemistry. The discussion is illustrated with results from simulations of three specific systems: bromine adsorption on silver (100), underpotential deposition of copper on gold (111), and electrodeposition of urea on platinum (100).
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
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
MUSiC - An Automated Scan for Deviations between Data and Monte Carlo Simulation
Meyer, Arnd
2010-02-10
A model independent analysis approach is presented, systematically scanning the data for deviations from the standard model Monte Carlo expectation. Such an analysis can contribute to the understanding of the CMS detector and the tuning of event generators. The approach is sensitive to a variety of models of new physics, including those not yet thought of.
Monte Carlo Characterization of a Pulsed Laser-Wakefield Driven Monochromatic
Umstadter, Donald
Monte Carlo Characterization of a Pulsed Laser-Wakefield Driven Monochromatic X-Ray Source S. D facility at the University of Nebraska- Lincoln (UNL) is a 100-TW, 30-fs pulsed Ti:sapphire laser system. Diocles is routinely used to accelerate electron beams by means of laser-wakefield acceleration, which
Menut, Laurent
the a priori uncertainties in anthropogenic NOx and volatile organic compounds (VOC) emissions: (1) The a posteriori probability density function (pdf) for NOx emissions is not modified in its averageBayesian Monte Carlo analysis applied to regional-scale inverse emission modeling for reactive
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
A quantum Monte Carlo calculation of the ground state energy of the hydrogen molecule
Anderson, James B.
A quantum Monte Carlo calculation of the ground state energy of the hydrogen molecule Carol A report here calculations of the ground state energy for the relatively simple system of the hydrogen-1264 (Received 20 August 1990; accepted 6 November 1990) We have calculated the ground state energy
Improved quantum Monte Carlo calculation of the ground-state energy of the hydrogen molecule
Anderson, James B.
Improved quantum Monte Carlo calculation of the ground-state energy of the hydrogen molecule Bin Carlo calculation of the nonrelativistic ground-state energy of the hydrogen molecule, without the use calculations of the energy of the hydrogen molecule and increasingly accurate experimental measurements
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
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
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
Auxiliary Field Diffusion Monte Carlo calculation of ground state properties of neutron drops
Francesco Pederiva; A. Sarsa; K. E. Schmidt; S. Fantoni
2004-03-23
The Auxiliary Field Diffusion Monte Carlo method has been applied to simulate droplets of 7 and 8 neutrons. Results for realistic nucleon-nucleon interactions, which include tensor, spin--orbit and three--body forces, plus a standard one--body confining potential, have been compared with analogous calculations obtained with Green's Function Monte Carlo methods. We have studied the dependence of the binding energy, the one--body density and the spin--orbit splittings of $^7n$ on the depth of the confining potential. The results obtained show an overall agreement between the two quantum Monte Carlo methods, although there persist differences in the evaluation of spin--orbit forces, as previously indicated by bulk neutron matter calculations. Energy density functional models, largely used in astrophysical applications, seem to provide results significantly different from those of quantum simulations. Given its scaling behavior in the number of nucleons, the Auxiliary Field Diffusion Monte Carlo method seems to be one of the best candidate to perform {\\sl ab initio} calculations on neutron rich nuclei.
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
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
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
/ 24 #12;SDEs in Finance In computational finance, stochastic differential equations are used to model the behaviour of stocks interest rates exchange rates weather electricity/gas demand crude oil prices . . . Mike Giles (Oxford) Monte Carlo methods 2 3 / 24 #12;SDEs in Finance Stochastic differential equations
Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford
Giles, Mike
in Finance In computational finance, stochastic differential equations are used to model the behaviour of stocks interest rates exchange rates weather electricity/gas demand crude oil prices . . . Mike Giles (Oxford) Monte Carlo methods 2 3 / 24 SDEs in Finance Stochastic differential equations are just ordinary
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
Rotating and static sources for gamma knife radiosurgery systems: Monte Carlo studies
Yu, Peter K.N.
Rotating and static sources for gamma knife radiosurgery systems: Monte Carlo studies J. Y. C of the 201 static sources Leksell gamma knife, LGK . The rotating sources of RGSs simulate an infinite number by the surrounding normal brain tissues, which is a resultant of 201 static 60 Co sources. Each individual beam
QUEEG: A Monte Carlo Event Generator for Quasielastic Scattering on Deuterium
Gilfoyle, Jerry
QUEEG: A Monte Carlo Event Generator for Quasielastic Scattering on Deuterium G.P. Gilfoyle1 , J. Examples of the use of the event generator are shown. The source and Makefiles are available in the CLAS12 an event generator for quasielastic scattering off nucleons in deuterium. This work was motivated
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
Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous
Pasko, Victor
Monte Carlo model for analysis of thermal runaway electrons in streamer tips in transient luminous in transient luminous events (TLEs) termed sprites, which occur in the altitude range 4090 km in the Earth modeling results indicate that the $10 Ek fields are able to accelerate a fraction of low-energy (several e
Monte Carlo study of a luminosity detector for the International Linear Collider
H. Abramowicz; R. Ingbir; S. Kananov; A. Levy
2005-08-11
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.
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
Ab-initio Kinetic Monte Carlo Model of Ionic Conduction in Bulk Yttria-stabilized Zirconia
Cai, Wei
Ab-initio Kinetic Monte Carlo Model of Ionic Conduction in Bulk Yttria-stabilized Zirconia Eunseok in bulk single crystal Yttria-stabilized Zirconia. An interacting energy barrier model is developed dynamics to simulate the vacancy diffusion in Yttria-stabilized Zirconia (YSZ). They concluded
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
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
Local and chain dynamics in miscible polymer blends: A Monte Carlo simulation study
Luettmer-Strathmann, Jutta
44325-4001 Received 7 November 2005; accepted 1 March 2006; published online 5 May 2006 Local chain of the chains. These are combined with a local mobility determined from the acceptance rate and the effectiveLocal and chain dynamics in miscible polymer blends: A Monte Carlo simulation study Jutta Luettmer
Coupled Electron-Ion Monte Carlo Calculations of Dense Metallic Hydrogen Carlo Pierleoni,1
May 2004; published 27 September 2004) We present an efficient new Monte Carlo method which couples structure and higher melting temperatures of the proton crystal than do Car-Parrinello molecular dynamics is unsatisfactory because energy differences among differ- ent crystalline phases are small requiring accurate total
Green's function Monte Carlo calculation for the ground state of helium trimers
Cabral, F.; Kalos, M.H.
1981-02-01
The ground state energy of weakly bound boson trimers interacting via Lennard-Jones (12,6) pair potentials is calculated using a Monte Carlo Green's Function Method. Threshold coupling constants for self binding are obtained by extrapolation to zero binding.
Instabilities in Molecular Dynamics Integrators used in Hybrid Monte Carlo Simulations
B. Joo; UKQCD Collaboration
2001-10-11
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.
The effects of mapping CT images to Monte Carlo materials on GEANT4 proton simulation accuracy
Barnes, Samuel; McAuley, Grant; Slater, James; Wroe, Andrew
2013-04-15
Purpose: Monte Carlo simulations of radiation therapy require conversion from Hounsfield units (HU) in CT images to an exact tissue composition and density. The number of discrete densities (or density bins) used in this mapping affects the simulation accuracy, execution time, and memory usage in GEANT4 and other Monte Carlo code. The relationship between the number of density bins and CT noise was examined in general for all simulations that use HU conversion to density. Additionally, the effect of this on simulation accuracy was examined for proton radiation. Methods: Relative uncertainty from CT noise was compared with uncertainty from density binning to determine an upper limit on the number of density bins required in the presence of CT noise. Error propagation analysis was also performed on continuously slowing down approximation range calculations to determine the proton range uncertainty caused by density binning. These results were verified with Monte Carlo simulations. Results: In the presence of even modest CT noise (5 HU or 0.5%) 450 density bins were found to only cause a 5% increase in the density uncertainty (i.e., 95% of density uncertainty from CT noise, 5% from binning). Larger numbers of density bins are not required as CT noise will prevent increased density accuracy; this applies across all types of Monte Carlo simulations. Examining uncertainty in proton range, only 127 density bins are required for a proton range error of <0.1 mm in most tissue and <0.5 mm in low density tissue (e.g., lung). Conclusions: By considering CT noise and actual range uncertainty, the number of required density bins can be restricted to a very modest 127 depending on the application. Reducing the number of density bins provides large memory and execution time savings in GEANT4 and other Monte Carlo packages.
Baes, Maarten
2008-01-01
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
Miura, Shinichi [Institute for Molecular Science, 38 Myodaiji, Okazaki 444-8585 (Japan)
2007-03-21
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.
Numerical thermalization in particle-in-cell simulations with Monte-Carlo collisions
Lai, P. Y.; Lin, T. Y.; Lin-Liu, Y. R.; Chen, S. H.
2014-12-15
Numerical thermalization in collisional one-dimensional (1D) electrostatic (ES) particle-in-cell (PIC) simulations was investigated. Two collision models, the pitch-angle scattering of electrons by the stationary ion background and large-angle collisions between the electrons and the neutral background, were included in the PIC simulation using Monte-Carlo methods. The numerical results show that the thermalization times in both models were considerably reduced by the additional Monte-Carlo collisions as demonstrated by comparisons with Turner's previous simulation results based on a head-on collision model [M. M. Turner, Phys. Plasmas 13, 033506 (2006)]. However, the breakdown of Dawson's scaling law in the collisional 1D ES PIC simulation is more complicated than that was observed by Turner, and the revised scaling law of the numerical thermalization time with numerical parameters are derived on the basis of the simulation results obtained in this study.
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
2012-09-04
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.
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)
2014-01-28
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.
Quantum Monte Carlo calculations of excited states in A = 6--8 nuclei
Steven C. Pieper; R. B. Wiringa; J. Carlson
2004-10-13
A variational Monte Carlo method is used to generate sets of orthogonal trial functions, Psi_T(J^pi,T), for given quantum numbers in various light p-shell nuclei. These Psi_T are then used as input to Green's function Monte Carlo calculations of first, second, and higher excited (J^pi,T) states. Realistic two- and three-nucleon interactions are used. We find that if the physical excited state is reasonably narrow, the GFMC energy converges to a stable result. With the combined Argonne v_18 two-nucleon and Illinois-2 three-nucleon interactions, the results for many second and higher states in A = 6--8 nuclei are close to the experimental values.
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.
2015-08-01
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
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
2015-01-01
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...
Monte Carlo simulation to investigate the formation of molecular hydrogen and its deuterated forms
Sahu, DIpen; Majumdar, Liton; Chakrabarti, Sandip K
2015-01-01
$H_2$ is the most abundant interstellar species. Its deuterated forms ($HD$ and $D_2$) are also significantly abundant. Huge abundances of these molecules could be explained by considering the chemistry occurring on the interstellar dust. Because of its simplicity, Rate equation method is widely used to study the formation of grain-surface species. However, since recombination efficiency of formation of any surface species are heavily dependent on various physical and chemical parameters, Monte Carlo method would be best method suited to take care of randomness of the processes. We perform Monte Carlo simulation to study the formation of $H_2$, $HD$ and $D_2$ on interstellar ices. Adsorption energies of surface species are the key inputs for the formation of any species on interstellar dusts but binding energies of deuterated species are yet to known with certainty. A zero point energy correction exists between hydrogenated and deuterated species which should be considered while modeling the chemistry on the ...
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)
2013-07-15
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.
A Monte Carlo study of double logarithms in the small x region
Chachamis, G
2015-01-01
We investigate the effect of the resummation of collinear double logarithms in the BFKL gluon Green function using the Monte Carlo event generator BFKLex. The resummed collinear terms in transverse momentum space were calculated in Ref. [1] and correspond to the addition to the NLO BFKL kernel of a Bessel function of the first kind whose argument contains the strong coupling and a double logarithm of the ratio of the squared transverse momenta of the reggeized gluons. We discuss how these additional terms improve the collinear convergence of the whole approach and reduce the asymptotic growth with energy of cross sections. Taking advantage of the Monte Carlo implementation, we show how the new results reduce the diffusion of the gluon ladder into infrared and ultraviolet transverse momentum scales, while strongly affecting final state configurations by reducing the mini-jet multiplicity.
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)
2014-02-01
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.
Fully Differential Monte-Carlo Generator Dedicated to TMDs and Bessel-Weighted Asymmetries
Aghasyan, Mher M.; Avakian, Harut A.
2013-10-01
We present studies of double longitudinal spin asymmetries in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator, which includes quark intrinsic transverse momentum within the generalized parton model based on the fully differential cross section for the process. Additionally, we apply Bessel-weighting to the simulated events to extract transverse momentum dependent parton distribution functions and also discuss possible uncertainties due to kinematic correlation effects.
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
2009-05-04
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.
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)
2013-12-15
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.
An analysis of 4-quark energies in SU(2) lattice Monte Carlo
Sadataka Furui; Bilal Masud
1998-09-12
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.
Hybrid Monte Carlo with Wilson Dirac operator on the Fermi GPU
Abhijit Chakrabarty; Pushan Majumdar
2012-07-10
In this article we present our implementation of a Hybrid Monte Carlo algorithm for Lattice Gauge Theory using two degenerate flavours of Wilson-Dirac fermions on a Fermi GPU. We find that using registers instead of global memory speeds up the code by almost an order of magnitude. To map the array variables to scalars, so that the compiler puts them in the registers, we use code generators. Our final program is more than 10 times faster than a generic single CPU.
Maximum likelihood parameter estimation in time series models using sequential Monte Carlo
Yildirim, Sinan
2013-06-11
, 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...
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.
2015-06-30
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
Using a Monte-Carlo-based approach to evaluate the uncertainty on fringe projection technique
Molimard, Jérôme
2013-01-01
A complete uncertainty analysis on a given fringe projection set-up has been performed using Monte-Carlo approach. In particular the calibration procedure is taken into account. Two applications are given: at a macroscopic scale, phase noise is predominant whilst at microscopic scale, both phase noise and calibration errors are important. Finally, uncertainty found at macroscopic scale is close to some experimental tests (~100 {\\mu}m).
NuWro Monte Carlo generator of neutrino interactions - first electron scattering results
Jakub Zmuda; Krzysztof M. Graczyk; Cezary Juszczak; Jan T. Sobczyk
2015-11-05
NuWro Monte Carlo generator of events is presented. It is a numerical environment containing all necessary ingredients to simulate interactions of neutrinos with nucleons and nuclei in realistic experimental situation in wide neutrino energy range. It can be used both for data analysis as well as studies of nuclear effects in neutrino interactions. The first results and functionalities of eWro - module of NuWro dedicated to electron nucleus scattering - are also presented.
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)
2013-12-15
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
2012-01-01
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.
Study of predominant hadronic modes of $?$-lepton using a Monte Carlo generator TAUOLA
O. Shekhovtsova
2015-08-22
TAUOLA is a Monte Carlo generator dedicated to generating tau-lepton decays and it is used in the analysis of experimental data both at B-factories and LHC. TAUOLA is a long-term project that started in the 90's and has been under development up to now. In this note we discuss the status of the predominant hadronic tau-lepton decays into two ($Br \\simeq 25.52\\%$) and three pions ($Br \\simeq 18.67\\%$).
Tesfatsion, Leigh
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 markets is a notoriously difficult process, due to physical constraints on electricity generation and flow
Korhonen, H; Briquet, M; Soriano, M Flores; Hubrig, S; Savanov, I; Hackman, T; Ilyin, I V; Eulaers, E; Pessemier, W
2013-01-01
Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods: High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. Results: We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals som...
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
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
Dornheim, Tobias; Groth, Simon; Filinov, Alexey; Bonitz, Michael
2015-01-01
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...
Hart, S. W. D.; Maldonado, G. Ivan; Celik, Cihangir; Leal, Luiz C
2014-01-01
For many Monte Carlo codes cross sections are generally only created at a set of predetermined temperatures. This causes an increase in error as one moves further and further away from these temperatures in the Monte Carlo model. This paper discusses recent progress in the Scale Monte Carlo module KENO to create problem dependent, Doppler broadened, cross sections. Currently only broadening the 1D cross sections and probability tables is addressed. The approach uses a finite difference method to calculate the temperature dependent cross-sections for the 1D data, and a simple linear-logarithmic interpolation in the square root of temperature for the probability tables. Work is also ongoing to address broadening theS (alpha , beta) tables. With the current approach the temperature dependent cross sections are Doppler broadened before transport starts, and, for all but a few isotopes, the impact on cross section loading is negligible. Results can be compared with those obtained by using multigroup libraries, as KENO currently does interpolation on the multigroup cross sections to determine temperature dependent cross-sections. Current results compare favorably with these expected results.
Nonequilibrium candidate Monte Carlo: A new tool for efficient equilibrium simulation
Nilmeier, Jerome P.; Crooks, Gavin E.; Minh, David D. L.; Chodera, John D.
2011-11-08
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.
Alhassan, Erwin; Duan, Junfeng; Gustavsson, Cecilia; Koning, Arjan; Pomp, Stephan; Rochman, Dimitri; Österlund, Michael
2013-01-01
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
2013-04-04
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.
Jamieson, Bruce
International Snow Science Workshop Grenoble - Chamonix Mont-Blanc - 2013 Validating. INTRODUCTION Snow avalanche risk assessments for development in avalanche terrain require estimates of not just extreme (100 to 300 year), but interim (Snow
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
Xu, Zao
We present a numerical study of the near-surface underwater solar light statistics using the state-of-the-art Monte Carlo radiative transfer (RT) simulations in the coupled atmosphere-ocean system. Advanced variance-reduction ...
Kurebayashi, Shinya, 1976-
2004-01-01
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 ...
Tutt, Teresa Elizabeth
2009-05-15
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 ...
Erickson, Lori
1995-01-01
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...
A Positive-Weight Next-to-Leading-Order Monte Carlo for e+e- Annihilation to Hadrons
Oluseyi Latunde-Dada; Stefan Gieseke; Bryan Webber
2007-02-20
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.
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
Barrera, C A; Moran, M J
2007-08-21
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.
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.
2011-02-15
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.
Wayne Chuko; Jerry Gould
2002-07-08
This report describes work accomplished in the project, titled ''Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels.'' The Phase 1 of the program involved development of in-situ temper diagrams for two gauges of representative dual-phase and martensitic grades of steels. The results showed that tempering is an effective way of reducing hold-time sensitivity (HTS) in hardenable high-strength sheet steels. In Phase 2, post-weld cooling rate techniques, incorporating tempering, were evaluated to reduce HTS for the same four steels. Three alternative methods, viz., post-heating, downsloping, and spike tempering, for HTS reduction were investigated. Downsloping was selected for detailed additional study, as it appeared to be the most promising of the cooling rate control methods. The downsloping maps for each of the candidate steels were used to locate the conditions necessary for the peak response. Three specific downslope conditions (at a fix ed final current for each material, timed for a zero-, medium-, and full-softening response) were chosen for further metallurgical and mechanical testing. Representative samples, were inspected metallographically, examining both local hardness variations and microstructures. The resulting downslope diagrams were found to consist largely of a C-curve. The softening observed in these curves, however, was not supported by subsequent metallography, which showed that all welds made, regardless of material and downslope condition, were essentially martensitic. CCT/TTT diagrams, generated based on microstructural modeling done at Oak Ridge National Laboratories, showed that minimum downslope times of 2 and 10 s for the martensitic and dual-phase grades of steels, respectively, were required to avoid martensite formation. These times, however, were beyond those examined in this study. These results show that downsloping is not an effective means of reducing HTS for production resistance spot welding (RSW). The necessary downslope times (2-10s) are prohibited by the welding rates currently used today (up to 60 welds/s). Based on the observations made in this study, spike tempering appears to be the best compromise of microstructural improvement and short cycle time. It is recommended that future work be focused on exploring the robustness of this approach, and its applicability for a wider range of steels.
Wu, May; Zhang, Zhonglong
2015-09-01
Using the Soil and Water Assessment Tool (SWAT) for large-scale watershed modeling could be useful for evaluating the quality of the water in regions that are dominated by nonpoint sources in order to identify potential “hot spots” for which mitigating strategies could be further developed. An analysis of water quality under future scenarios in which changes in land use would be made to accommodate increased biofuel production was developed for the Missouri River Basin (MoRB) based on a SWAT model application. The analysis covered major agricultural crops and biofuel feedstock in the MoRB, including pasture land, hay, corn, soybeans, wheat, and switchgrass. The analysis examined, at multiple temporal and spatial scales, how nitrate, organic nitrogen, and total nitrogen; phosphorus, organic phosphorus, inorganic phosphorus, and total phosphorus; suspended sediments; and water flow (water yield) would respond to the shifts in land use that would occur under proposed future scenarios. The analysis was conducted at three geospatial scales: (1) large tributary basin scale (two: Upper MoRB and Lower MoRB); (2) regional watershed scale (seven: Upper Missouri River, Middle Missouri River, Middle Lower Missouri River, Lower Missouri River, Yellowstone River, Platte River, and Kansas River); and (3) eight-digit hydrologic unit (HUC-8) subbasin scale (307 subbasins). Results showed that subbasin-level variations were substantial. Nitrogen loadings decreased across the entire Upper MoRB, and they increased in several subbasins in the Lower MoRB. Most nitrate reductions occurred in lateral flow. Also at the subbasin level, phosphorus in organic, sediment, and soluble forms was reduced by 35%, 45%, and 65%, respectively. Suspended sediments increased in 68% of the subbasins. The water yield decreased in 62% of the subbasins. In the Kansas River watershed, the water quality improved significantly with regard to every nitrogen and phosphorus compound. The improvement was clearly attributable to the conversion of a large amount of land to switchgrass. The Middle Lower Missouri River and Lower Missouri River were identified as hot regions. Further analysis identified four subbasins (10240002, 10230007, 10290402, and 10300200) as being the most vulnerable in terms of sediment, nitrogen, and phosphorus loadings. Overall, results suggest that increasing the amount of switchgrass acreage in the hot spots should be considered to mitigate the nutrient loads. The study provides an analytical method to support stakeholders in making informed decisions that balance biofuel production and water sustainability.
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
2014-05-15
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))
1991-01-01
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.
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)
1998-02-01
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.
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
2010-04-23
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.
Transport in open spin chains: A Monte Carlo wave-function approach
Mathias Michel; Ortwin Hess; Hannu Wichterich; Jochen Gemmer
2008-03-07
We investigate energy transport in several two-level atom or spin-1/2 models by a direct coupling to heat baths of different temperatures. The analysis is carried out on the basis of a recently derived quantum master equation which describes the nonequilibrium properties of internally weakly coupled systems appropriately. For the computation of the stationary state of the dynamical equations, we employ a Monte Carlo wave-function approach. The analysis directly indicates normal diffusive or ballistic transport in finite models and hints toward an extrapolation of the transport behavior of infinite models.
S. Frixione; E. Laenen; P. Motylinski; B. R. Webber
2007-02-20
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
Monte Carlo Generators for Studies of the 3D Structure of the Nucleon
Avagyan, Harut A. [JLAB
2015-01-01
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 simulations of channeling spectra recorded for samples containing complex defects
Jagielski, Jacek; Turos, Prof. Andrzej; Nowicki, Lech; Jozwik, P.; Shutthanandan, Vaithiyalingam; Zhang, Yanwen; Sathish, N.; Thome, Lionel; Stonert, A.; Jozwik-Biala, Iwona
2012-01-01
The aim of the present paper is to describe the current status of the development of McChasy, a Monte Carlo simulation code, to make it suitable for the analysis of dislocations and dislocation loops in crystals. Such factors like the shape of the bent channel and geometrical distortions of the crystalline structure in the vicinity of dislocation has been discussed. The results obtained demonstrate that the new procedure applied to the spectra recorded on crystals containing dislocation yields damage profiles which are independent of the energy of the analyzing beam.
Monte Carlo simulations of channeling spectra recorded for samples containing complex defects
Jagielski, Jacek K.; Turos, Andrzej W.; Nowicki, L.; Jozwik, Przemyslaw A.; Shutthanandan, V.; Zhang, Yanwen; Sathish, N.; Thome, Lionel; Stonert, A.; Jozwik Biala, Iwona
2012-02-15
The main aim of the present paper is to describe the current status of the development of McChasy, a Monte Carlo simulation code, to make it suitable for the analysis of dislocations and dislocation loops in crystals. Such factors like the shape of the bent channel and geometrical distortions of the crystalline structure in the vicinity of dislocation has been discussed. Several examples of the analysis performed at different energies of analyzing ions are presented. The results obtained demonstrate that the new procedure applied to the spectra recorded on crystals containing dislocation yields damage profiles which are independent of the energy of the analyzing beam.
The Imprints of IMBHs on the Structure of Globular Clusters: Monte-Carlo Simulations
Stefan Umbreit; John M. Fregeau; Frederic A. Rasio
2008-03-06
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.
Four-Quark Binding Energies from SU(2) Lattice Monte Carlo
A. M. Green; C. Michael; M. E. Sainio
1994-04-11
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.
Study of DCX reaction on medium nuclei with Monte-Carlo Shell Model
Wu, H. C.; Gibbs, W. R.
2010-08-04
In this work a method is introduced to calculate the DCX reaction in the framework of Monte-Carlo Shell Model (MCSM). To facilitate the use of Zero-temperature formalism of MCSM, the Double-Isobaric-Analog State (DIAS) is derived from the ground state by using isospin shifting operator. The validity of this method is tested by comparing the MCSM results to those of the SU(3) symmetry case. Application of this method to DCX on {sup 56}Fe and {sup 93}Nb is discussed.
Monte-Carlo study of the phase transition in the AA-stacked bilayer graphene
A. A. Nikolaev; M. V. Ulybyshev
2014-12-04
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.
Monte Carlo generators for studies of the 3D structure of the nucleon
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Avakian, Harut; D'Alesio, U.; Murgia, F.
2015-01-23
In this study, 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.
Nuclear Level Density of ${}^{161}$Dy in the Shell Model Monte Carlo Method
Cem Özen; Yoram Alhassid; Hitoshi Nakada
2012-06-27
We extend the shell-model Monte Carlo applications to the rare-earth region to include the odd-even nucleus ${}^{161}$Dy. The projection on an odd number of particles leads to a sign problem at low temperatures making it impractical to extract the ground-state energy in direct calculations. We use level counting data at low energies and neutron resonance data to extract the shell model ground-state energy to good precision. We then calculate the level density of ${}^{161}$Dy and find it in very good agreement with the level density extracted from experimental data.
A Hybrid (Monte-Carlo/Deterministic) Approach for Multi-Dimensional Radiation Transport
Guillaume Bal; Anthony Davis; Ian Langmore
2011-05-07
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
2011-01-01
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.
Quantized vortices in {sup 4}He droplets: A quantum Monte Carlo study
Sola, E.; Casulleras, J.; Boronat, J.
2007-08-01
We present a diffusion Monte Carlo study of a vortex line excitation attached to the center of a {sup 4}He droplet at zero temperature. The vortex energy is estimated for droplets of increasing number of atoms, from N=70 up to 300, showing a monotonous increase with N. The evolution of the core radius and its associated energy, the core energy, is also studied as a function of N. The core radius is {approx}1 A in the center and increases when approaching the droplet surface; the core energy per unit volume stabilizes at a value 2.8 K{sigma}{sup -3} ({sigma}=2.556 A) for N{>=}200.
Quantum Monte Carlo simulation of a two-dimensional Bose gas
Pilati, S.; Boronat, J.; Casulleras, J.; Giorgini, S.
2005-02-01
The equation of state of a homogeneous two-dimensional Bose gas is calculated using quantum Monte Carlo methods. The low-density universal behavior is investigated using different interatomic model potentials, both finite ranged and strictly repulsive and zero ranged, supporting a bound state. The condensate fraction and the pair distribution function are calculated as a function of the gas parameter, ranging from the dilute to the strongly correlated regime. In the case of the zero-range pseudopotential we discuss the stability of the gaslike state for large values of the two-dimensional scattering length, and we calculate the critical density where the system becomes unstable against cluster formation.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Betzler, Benjamin R.; Kiedrowski, Brian C.; Brown, Forrest B.; Martin, William R.
2015-08-28
The time-dependent behavior of the energy spectrum in neutron transport was investigated with a formulation, based on continuous-time Markov processes, for computing ? eigenvalues and eigenvectors in an infinite medium. In this study, a research Monte Carlo code called “TORTE” (To Obtain Real Time Eigenvalues) was created and used to estimate elements of a transition rate matrix. TORTE is capable of using both multigroup and continuous-energy nuclear data, and verification was performed. Eigenvalue spectra for infinite homogeneous mixtures were obtained, and an eigenfunction expansion was used to investigate transient behavior of the neutron energy spectrum.
Theory of melting at high pressures: Amending density functional theory with quantum Monte Carlo
Shulenburger, L.; Desjarlais, M. P.; Mattsson, T. R.
2014-10-01
We present an improved first-principles description of melting under pressure based on thermodynamic integration comparing Density Functional Theory (DFT) and quantum Monte Carlo (QMC) treatments of the system. The method is applied to address the longstanding discrepancy between density functional theory (DFT) calculations and diamond anvil cell (DAC) experiments on the melting curve of xenon, a noble gas solid where van der Waals binding is challenging for traditional DFT methods. The calculations show excellent agreement with data below 20 GPa and that the high-pressure melt curve is well described by a Lindemann behavior up to at least 80 GPa, a finding in stark contrast to DAC data.
Boris Tomasik
2009-01-09
A Monte Carlo generator of the final state of hadrons emitted from an ultrarelativistic nuclear collision is introduced. An important feature of the generator is a possible fragmentation of the fireball and emission of the hadrons from fragments. Phase space distribution of the fragments is based on the blast wave model extended to azimuthally non-symmetric fireballs. Parameters of the model can be tuned and this allows to generate final states from various kinds of fireballs. A facultative output in the OSCAR1999A format allows for a comprehensive analysis of phase-space distributions and/or use as an input for an afterburner.
Thermonuclear reaction rate of $^{18}$Ne($\\alpha$,$p$)$^{21}$Na from Monte-Carlo calculations
Mohr, P; Iliadis, C
2014-01-01
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($?$,$p$)$^{21}$Na from Monte-Carlo calculations
P. Mohr; R. Longland; C. Iliadis
2014-12-14
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.
Monte-Carlo Simulation of Exclusive Channels in e+e- Annihilation at Low Energy
D. Anipko; S. Eidelman; A. Pak
2003-12-25
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.
Perera, Meewanage Dilina N; Li, Ying Wai; Eisenbach, Markus; Vogel, Thomas; Landau, David P
2015-01-01
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.
Camden, Jon P
2013-07-16
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).
Künstler, A; Strassmeier, K G
2015-01-01
Solar spots appear to decay linearly proportional to their size. The decay rate of solar spots is directly related to magnetic diffusivity, which itself is a key quantity for the length of a magnetic-activity cycle. Is a linear spot decay also seen on other stars, and is this in agreement with the large range of solar and stellar activity cycle lengths? We investigate the evolution of starspots on the rapidly-rotating ($P_{\\rm rot}$ $\\approx$ 24 d) K0 giant XX Tri, using consecutive time-series Doppler images. Our aim is to obtain a well-sampled movie of the stellar surface over many years, and thereby detect and quantify a starspot decay law for further comparison with the Sun. We obtained continuous high-resolution and phase-resolved spectroscopy with the 1.2-m robotic STELLA telescope on Tenerife over six years. For each observing season, we obtained between 5 to 7 independent Doppler images, one per stellar rotation, making up a total of 36 maps. To quantify starspot area decay and growth, we match the ob...
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)
2011-01-17
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.
Physics and Algorithm Enhancements for a Validated MCNP/X Monte Carlo Simulation Tool, Phase VII
McKinney, Gregg W [Los Alamos National Laboratory
2012-07-17
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
2008-10-01
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.
Berg, John M.; Veirs, D. Kirk; Vaughn, Randolph B.; Cisneros, Michael R.; Smith, Coleman A.
2000-06-01
Standard modeling approaches can produce the most likely values of the formation constants of metal-ligand complexes if a particular set of species containing the metal ion is known or assumed to exist in solution equilibrium with complexing ligands. Identifying the most likely set of species when more than one set is plausible is a more difficult problem to address quantitatively. A Monte Carlo method of data analysis is described that measures the relative abilities of different speciation models to fit optical spectra of open-shell actinide ions. The best model(s) can be identified from among a larger group of models initially judged to be plausible. The method is demonstrated by analyzing the absorption spectra of aqueous Pu(IV) titrated with nitrate ion at constant 2 molal ionic strength in aqueous perchloric acid. The best speciation model supported by the data is shown to include three Pu(IV) species with nitrate coordination numbers 0, 1, and 2. Formation constants are {beta}{sub 1}=3.2{+-}0.5 and {beta}{sub 2}=11.2{+-}1.2, where the uncertainties are 95% confidence limits estimated by propagating raw data uncertainties using Monte Carlo methods. Principal component analysis independently indicates three Pu(IV) complexes in equilibrium. (c) 2000 Society for Applied Spectroscopy.
Monte Carlo Simulations of Globular Cluster Evolution. IV. Direct Integration of Strong Interactions
John M. Fregeau; Frederic A. Rasio
2006-12-06
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 simulations of neutron shielding for the ATLAS forward region
Stekl, I; Kovalenko, V E; Vorobel, V; Leroy, C; Piquemal, F; Eschbach, R; Marquet, C
2000-01-01
The effectiveness of different types of neutron shielding for the ATLAS forward region has been studied by means of Monte-Carlo simulations and compared with the results of an experiment performed at the CERN PS. The simulation code is based on GEANT, FLUKA, MICAP and GAMLIB. GAMLIB is a new library including processes with gamma-rays produced in (n, gamma), (n, n'gamma) neutron reactions and is interfaced to the MICAP code. The effectiveness of different types of shielding against neutrons and gamma-rays, composed from different types of material, such as pure polyethylene, borated polyethylene, lithium-filled polyethylene, lead and iron, were compared. The results from Monte-Carlo simulations were compared to the results obtained from the experiment. The simulation results reproduce the experimental data well. This agreement supports the correctness of the simulation code used to describe the generation, spreading and absorption of neutrons (up to thermal energies) and gamma-rays in the shielding materials....
Energy density matrix formalism for interacting quantum systems: a quantum Monte Carlo study
Krogel, Jaron T; Kim, Jeongnim; Reboredo, Fernando A
2014-01-01
We develop an energy density matrix that parallels the one-body reduced density matrix (1RDM) for many-body quantum systems. Just as the density matrix gives access to the number density and occupation numbers, the energy density matrix yields the energy density and orbital occupation energies. The eigenvectors of the matrix provide a natural orbital partitioning of the energy density while the eigenvalues comprise a single particle energy spectrum obeying a total energy sum rule. For mean-field systems the energy density matrix recovers the exact spectrum. When correlation becomes important, the occupation energies resemble quasiparticle energies in some respects. We explore the occupation energy spectrum for the finite 3D homogeneous electron gas in the metallic regime and an isolated oxygen atom with ground state quantum Monte Carlo techniques imple- mented in the QMCPACK simulation code. The occupation energy spectrum for the homogeneous electron gas can be described by an effective mass below the Fermi level. Above the Fermi level evanescent behavior in the occupation energies is observed in similar fashion to the occupation numbers of the 1RDM. A direct comparison with total energy differences demonstrates a quantita- tive connection between the occupation energies and electron addition and removal energies for the electron gas. For the oxygen atom, the association between the ground state occupation energies and particle addition and removal energies becomes only qualitative. The energy density matrix provides a new avenue for describing energetics with quantum Monte Carlo methods which have traditionally been limited to total energies.
M. Alvioli; H. -J. Drescher; M. Strikman
2009-09-04
We developed a Monte Carlo event generator for production of nucleon configurations in complex nuclei consistently including effects of Nucleon-Nucleon (NN) correlations. Our approach is based on the Metropolis search for configurations satisfying essential constraints imposed by short- and long-range NN correlations, guided by the findings of realistic calculations of one- and two-body densities for medium-heavy nuclei. The produced event generator can be used for Monte Carlo (MC) studies of pA and AA collisions. We perform several tests of consistency of the code and comparison with previous models, in the case of high energy proton-nucleus scattering on an event-by-event basis, using nucleus configurations produced by our code and Glauber multiple scattering theory both for the uncorrelated and the correlated configurations; fluctuations of the average number of collisions are shown to be affected considerably by the introduction of NN correlations in the target nucleus. We also use the generator to estimate maximal possible gluon nuclear shadowing in a simple geometric model.
Cosmological parameters from CMB and other data: a Monte-Carlo approach
Antony Lewis; Sarah Bridle
2002-10-14
We present a fast Markov Chain Monte-Carlo exploration of cosmological parameter space. We perform a joint analysis of results from recent CMB experiments and provide parameter constraints, including sigma_8, from the CMB independent of other data. We next combine data from the CMB, HST Key Project, 2dF galaxy redshift survey, supernovae Ia and big-bang nucleosynthesis. The Monte Carlo method allows the rapid investigation of a large number of parameters, and we present results from 6 and 9 parameter analyses of flat models, and an 11 parameter analysis of non-flat models. Our results include constraints on the neutrino mass (m_nu < 0.3eV), equation of state of the dark energy, and the tensor amplitude, as well as demonstrating the effect of additional parameters on the base parameter constraints. In a series of appendices we describe the many uses of importance sampling, including computing results from new data and accuracy correction of results generated from an approximate method. We also discuss the different ways of converting parameter samples to parameter constraints, the effect of the prior, assess the goodness of fit and consistency, and describe the use of analytic marginalization over normalization parameters.
Use of SCALE Continuous-Energy Monte Carlo Tools for Eigenvalue Sensitivity Coefficient Calculations
Perfetti, Christopher M [ORNL] [ORNL; Rearden, Bradley T [ORNL] [ORNL
2013-01-01
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.
Surface Structures of Cubo-octahedral Pt-Mo Catalyst Nanoparticles from Monte Carlo Simulations
Wang, Guofeng; Van Hove, M.A.; Ross, P.N.; Baskes, M.I.
2005-03-31
The surface structures of cubo-octahedral Pt-Mo nanoparticles have been investigated using the Monte Carlo method and modified embedded atom method potentials that we developed for Pt-Mo alloys. The cubo-octahedral Pt-Mo nanoparticles are constructed with disordered fcc configurations, with sizes from 2.5 to 5.0 nm, and with Pt concentrations from 60 to 90 at. percent. The equilibrium Pt-Mo nanoparticle configurations were generated through Monte Carlo simulations allowing both atomic displacements and element exchanges at 600 K. We predict that the Pt atoms weakly segregate to the surfaces of such nanoparticles. The Pt concentrations in the surface are calculated to be 5 to 14 at. percent higher than the Pt concentrations of the nanoparticles. Moreover, the Pt atoms preferentially segregate to the facet sites of the surface, while the Pt and Mo atoms tend to alternate along the edges and vertices of these nanoparticles. We found that decreasing the size or increasing the Pt concentration leads to higher Pt concentrations but fewer Pt-Mo pairs in the Pt-Mo nanoparticle surfaces.
A Monte Carlo Study of Multiplicity Fluctuations in Pb-Pb Collisions at LHC Energies
Ramni Gupta
2015-01-15
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.
SIMDET - Version 4 A Parametric Monte Carlo for a TESLA Detector
M. Pohl; H. J. Schreiber
2002-06-05
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.
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)
2013-12-01
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.
Ibrahim, Ahmad M; Wilson, P.; Sawan, M.; Mosher, Scott W; Peplow, Douglas E.; Grove, Robert E
2013-01-01
Three mesh adaptivity algorithms were developed to facilitate and expedite the use of the CADIS and FW-CADIS hybrid Monte Carlo/deterministic techniques in accurate full-scale neutronics simulations of fusion energy systems with immense sizes and complicated geometries. First, a macromaterial approach enhances the fidelity of the deterministic models without changing the mesh. Second, a deterministic mesh refinement algorithm generates meshes that capture as much geometric detail as possible without exceeding a specified maximum number of mesh elements. Finally, a weight window coarsening algorithm decouples the weight window mesh and energy bins from the mesh and energy group structure of the deterministic calculations in order to remove the memory constraint of the weight window map from the deterministic mesh resolution. The three algorithms were used to enhance an FW-CADIS calculation of the prompt dose rate throughout the ITER experimental facility and resulted in a 23.3% increase in the number of mesh tally elements in which the dose rates were calculated in a 10-day Monte Carlo calculation. Additionally, because of the significant increase in the efficiency of FW-CADIS simulations, the three algorithms enabled this difficult calculation to be accurately solved on a regular computer cluster, eliminating the need for a world-class super computer.
Multi-Scale Multi-physics Methods Development for the Calculation of Hot-Spots in the NGNP
Downar, Thomas; Seker, Volkan
2013-04-30
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.
Pugh, Thomas J. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Munsell, Mark F. [Department of Biostatistics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Choi, Seungtaek; Nguyen, Quyhn Nhu; Mathai, Benson [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Zhu, X. Ron; Sahoo, Narayan; Gillin, Michael; Johnson, Jennifer L.; Amos, Richard A. [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Dong, Lei [Scripps Proton Therapy Center, San Diego, California (United States); Mahmood, Usama; Kuban, Deborah A.; Frank, Steven J.; Hoffman, Karen E.; McGuire, Sean E. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Lee, Andrew K., E-mail: aklee@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
2013-12-01
Purpose: To report quality of life (QOL)/toxicity in men treated with proton beam therapy for localized prostate cancer and to compare outcomes between passively scattered proton therapy (PSPT) and spot-scanning proton therapy (SSPT). Methods and Materials: Men with localized prostate cancer enrolled on a prospective QOL protocol with a minimum of 2 years' follow-up were reviewed. Comparative groups were defined by technique (PSPT vs SSPT). Patients completed Expanded Prostate Cancer Index Composite questionnaires at baseline and every 3-6 months after proton beam therapy. Clinically meaningful differences in QOL were defined as ?0.5 × baseline standard deviation. The cumulative incidence of modified Radiation Therapy Oncology Group grade ?2 gastrointestinal (GI) or genitourinary (GU) toxicity and argon plasma coagulation were determined by the Kaplan-Meier method. Results: A total of 226 men received PSPT, and 65 received SSPT. Both PSPT and SSPT resulted in statistically significant changes in sexual, urinary, and bowel Expanded Prostate Cancer Index Composite summary scores. Only bowel summary, function, and bother resulted in clinically meaningful decrements beyond treatment completion. The decrement in bowel QOL persisted through 24-month follow-up. Cumulative grade ?2 GU and GI toxicity at 24 months were 13.4% and 9.6%, respectively. There was 1 grade 3 GI toxicity (PSPT group) and no other grade ?3 GI or GU toxicity. Argon plasma coagulation application was infrequent (PSPT 4.4% vs SSPT 1.5%; P=.21). No statistically significant differences were appreciated between PSPT and SSPT regarding toxicity or QOL. Conclusion: Both PSPT and SSPT confer low rates of grade ?2 GI or GU toxicity, with preservation of meaningful sexual and urinary QOL at 24 months. A modest, yet clinically meaningful, decrement in bowel QOL was seen throughout follow-up. No toxicity or QOL differences between PSPT and SSPT were identified. Long-term comparative results in a larger patient cohort are warranted.
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
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Mayers, Matthew Z.; Berkelbach, Timothy C.; Hybertsen, Mark S.; Reichman, David R.
2015-10-09
Ground-state diffusion Monte Carlo is used to investigate the binding energies and intercarrier radial probability distributions of excitons, trions, and biexcitons in a variety of two-dimensional transition-metal dichalcogenide materials. We compare these results to approximate variational calculations, as well as to analogous Monte Carlo calculations performed with simplified carrier interaction potentials. Our results highlight the successes and failures of approximate approaches as well as the physical features that determine the stability of small carrier complexes in monolayer transition-metal dichalcogenide materials. In conclusion, we discuss points of agreement and disagreement with recent experiments.
Pilati, S.; Giorgini, S.; Sakkos, K.; Boronat, J.; Casulleras, J.
2006-10-15
By using exact path-integral Monte Carlo methods we calculate the equation of state of an interacting Bose gas as a function of temperature both below and above the superfluid transition. The universal character of the equation of state for dilute systems and low temperatures is investigated by modeling the interatomic interactions using different repulsive potentials corresponding to the same s-wave scattering length. The results obtained for the energy and the pressure are compared to the virial expansion for temperatures larger than the critical temperature. At very low temperatures we find agreement with the ground-state energy calculated using the diffusion Monte Carlo method.
Nakano, Y. Yamazaki, A.; Watanabe, K.; Uritani, A.; Ogawa, K.; Isobe, M.
2014-11-15
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.
MAIN APPLICATIONS Spot welding
De Luca, Alessandro
and speed over the entire working envelope. Adaptability IRB 6400 is designed to be compact with a small interference radius to ensure flexible installations in areas with high density of production equipment a quick return to full production. Reliability and safety IRB 6400 features robust all-steel construction
Rea, H. E.
1958-01-01
-56, hack off the stems and treat 8-inch stubs of grass in the bloom stage. Use 3 gallons of HCA (90 percent hexachloroace- tone) in 100 gallons of kerosene or other suitable oils for combined contact and residual effectiveness in con- trolling...
Elliott, Fred C.; Norris, M. J.; Rea, H. E.
1955-01-01
-treat Johnsongrass in cotton in 19 54. Power-driven sprayers normally used for in- tect control in row crops were modified for Yose. A spray pressure of 12 pounds re inch was used. Two systems of the grass were tried. In one system the crenr applying the oil... crown-oilings with naphtha, 83 percent in 7 tests by 3 oil- ings, 95 percent in 6 tests by 4 oilings and 98 percent in 4 tests by 5 to 7 oilings. The use of mixtures of 50 percent naphtha and 50 per- cent kerosene or diesel fuel oil reduced...
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
Glyde, Henry R.
, dense Bose liquid and the connection between BEC in an ideal gas and superfluidity was not at all clearNatural orbitals and Bose-Einstein condensates in traps: A diffusion Monte Carlo analysis J. L. Du diffusion Monte Carlo methods and it is diagonalized to obtain the ``natural'' single-particle orbitals
Alfè, Dario
of 76 kJ/mole.2 The kinetics of hydrogen intake by Mg is quite slow because of a relatively large energyHydrogen dissociation on Mg(0001) studied via quantum Monte Carlo calculations M. Pozzo1,2 and D have used diffusion Monte Carlo DMC simulations to calculate the energy barrier for H2 dissociation