Sample records for dynamic simulation tool

  1. Dynamic wind turbine models in power system simulation tool

    E-Print Network [OSTI]

    Dynamic wind turbine models in power system simulation tool DIgSILENT Anca D. Hansen, Florin Iov Iov, Poul Sørensen, Nicolaos Cutululis, Clemens Jauch, Frede Blaabjerg Title: Dynamic wind turbine system simulation tool PowerFactory DIgSILENT for different wind turbine concepts. It is the second

  2. ulvacsim.paper.doc 08/20/99 p. 1 of 23 Dynamic Simulation of a Multichamber CVD Cluster Tool

    E-Print Network [OSTI]

    Rubloff, Gary W.

    ulvacsim.paper.doc 08/20/99 p. 1 of 23 Dynamic Simulation of a Multichamber CVD Cluster Tool N-level dynamic simulator for an 8" CVD cluster tool (ULVAC-ERA1000). The simulator incorporates models, and volumes to reflect actual behavior, validated against experiments on the Ulvac tool. The process simulator

  3. An Analysis Tool for Flight Dynamics Monte Carlo Simulations

    E-Print Network [OSTI]

    Restrepo, Carolina 1982-

    2011-05-20T23:59:59.000Z

    and analysis work to understand vehicle operating limits and identify circumstances that lead to mission failure. A Monte Carlo simulation approach that varies a wide range of physical parameters is typically used to generate thousands of test cases...

  4. Tools for dynamic model development

    E-Print Network [OSTI]

    Schaber, Spencer Daniel

    2014-01-01T23:59:59.000Z

    For this thesis, several tools for dynamic model development were developed and analyzed. Dynamic models can be used to simulate and optimize the behavior of a great number of natural and engineered systems, from the ...

  5. Automating Dynamic Decoupling in Object-Oriented Modelling and Simulation Tools

    E-Print Network [OSTI]

    Como, Giacomo

    a Modelica transla- tor. Simulation tests demonstrate the technique, and the re- alised implementation than of simulation theory. In this work we refer as "EOO Modelling Tool" to a Modelica translator, to allow exemplifying the (more general) presented ideas. For a Modelica translator, the EOO modelling

  6. Developing an integrated building design tool by coupling building energy simulation and computational fluid dynamics programs

    E-Print Network [OSTI]

    Zhai, Zhiqiang, 1971-

    2003-01-01T23:59:59.000Z

    Building energy simulation (ES) and computational fluid dynamics (CFD) can play important roles in building design by providing essential information to help design energy-efficient, thermally comfortable and healthy ...

  7. Calibration and Validation of a Spar-Type Floating Offshore Wind Turbine Model using the FAST Dynamic Simulation Tool: Preprint

    SciTech Connect (OSTI)

    Browning, J. R.; Jonkman, J.; Robertson, A.; Goupee, A. J.

    2012-11-01T23:59:59.000Z

    In 2007, the FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL), was expanded to include capabilities that are suitable for modeling floating offshore wind turbines. In an effort to validate FAST and other offshore wind energy modeling tools, DOE funded the DeepCwind project that tested three prototype floating wind turbines at 1/50th scale in a wave basin, including a semisubmersible, a tension-leg platform, and a spar buoy. This paper describes the use of the results of the spar wave basin tests to calibrate and validate the FAST offshore floating simulation tool, and presents some initial results of simulated dynamic responses of the spar to several combinations of wind and sea states.

  8. Molecular dynamics simulation: a tool for exploration and discovery using simple models

    E-Print Network [OSTI]

    D. C. Rapaport

    2014-11-13T23:59:59.000Z

    Emergent phenomena share the fascinating property of not being obvious consequences of the design of the system in which they appear. This characteristic is no less relevant when attempting to simulate such phenomena, given that the outcome is not always a foregone conclusion. The present survey focuses on several simple model systems that exhibit surprisingly rich emergent behavior, all studied by MD simulation. The examples are taken from the disparate fields of fluid dynamics, granular matter and supramolecular self-assembly. In studies of fluids modeled at the detailed microscopic level using discrete particles, the simulations demonstrate that complex hydrodynamic phenomena in rotating and convecting fluids, the Taylor-Couette and Rayleigh-B\\'enard instabilities, can not only be observed within the limited length and time scales accessible to MD, but even quantitative agreement can be achieved. Simulation of highly counterintuitive segregation phenomena in granular mixtures, again using MD methods, but now augmented by forces producing damping and friction, leads to results that resemble experimentally observed axial and radial segregation in the case of a rotating cylinder, and to a novel form of horizontal segregation in a vertically vibrated layer. Finally, when modeling self-assembly processes analogous to the formation of the polyhedral shells that package spherical viruses, simulation of suitably shaped particles reveals the ability to produce complete, error-free assembly, and leads to the important general observation that reversible growth steps contribute to the high yield. While there are limitations to the MD approach, both computational and conceptual, the results offer a tantalizing hint of the kinds of phenomena that can be explored, and what might be discovered when sufficient resources are brought to bear on a problem.

  9. FASTBUS simulation tools

    SciTech Connect (OSTI)

    Dean, T.D. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Haney, M.J. (Illinois Univ., Urbana, IL (United States))

    1991-10-01T23:59:59.000Z

    A generalized model of a FASTBUS master is presented. The model is used with simulation tools to aid in the specification, design, and production of FASTBUS slave modules. The model provides a mechanism to interact with the electrical schematics and software models to predict performance. The model is written in the IEEE std 1076-1987 hardware description language VHDL. A model of the ATC logic is also presented. VHDL was chosen to provide portability to various platforms and simulation tools. The models, in conjunction with most commercially available simulators, will perform all of the transactions specified in IEEE std 960-1989. The models may be used to study the behavior of electrical schematics and other software models and detect violations of the FASTBUS protocol. For example, a hardware design of a slave module could be studied, protocol violations detected and corrected before committing money to prototype development. The master model accepts a stream of high level commands from an ASCII file to initiate FASTBUS transactions. The high level command language is based on the FASTBUS standard routines listed in IEEE std 1177-1989. Using this standard-based command language to direct the model of the master, hardware engineers can simulate FASTBUS transactions in the language used by physicists and programmers to operate FASTBUS systems. 15 refs., 6 figs.

  10. Dynamic Positioning Simulator Dynamic Positioning Simulator

    E-Print Network [OSTI]

    Vuik, Kees

    Simulator 5 / 24 #12;Dynamic Positioning Simulator Dynamic Positioning Why Dynamic Positioning? Advantages Dynamic Positioning: No tugboats needed; Offshore set-up is quick; Power saving; Precision situations more on Ship: Wind Force Fw = 1 2 air V 2 rw CXw (rw )AT 1 2 air V 2 rw CYw (rw )AL Mw = 1 2 air V 2 rw CMw (rw

  11. The Xygra gun simulation tool.

    SciTech Connect (OSTI)

    Garasi, Christopher Joseph; Lamppa, Derek C.; Aubuchon, Matthew S.; Shirley, David Noyes; Robinson, Allen Conrad; Russo, Thomas V.

    2008-12-01T23:59:59.000Z

    Inductive electromagnetic launchers, or coilguns, use discrete solenoidal coils to accelerate a coaxial conductive armature. To date, Sandia has been using an internally developed code, SLINGSHOT, as a point-mass lumped circuit element simulation tool for modeling coilgun behavior for design and verification purposes. This code has shortcomings in terms of accurately modeling gun performance under stressful electromagnetic propulsion environments. To correct for these limitations, it was decided to attempt to closely couple two Sandia simulation codes, Xyce and ALEGRA, to develop a more rigorous simulation capability for demanding launch applications. This report summarizes the modifications made to each respective code and the path forward to completing interfacing between them.

  12. Next generation computational tools for extreme-scale simulation of dynamic fracture and fragmentation in three dimensions

    E-Print Network [OSTI]

    Seagraves, Andrew Nathan

    2013-01-01T23:59:59.000Z

    The accurate modeling of dynamic fracture and fragmentation remains one of the most difficult challenges in computational mechanics research. As part of this thesis, a scalable algorithm for modeling dynamic fracture and ...

  13. Optimization of naïve dynamic binary instrumentation Tools/

    E-Print Network [OSTI]

    Kleckner, Reid (Reid N.)

    2011-01-01T23:59:59.000Z

    The proliferation of dynamic program analysis tools has done much to ease the burden of developing complex software. However, creating such tools remains a challenge. Dynamic binary instrumentation frameworks such as ...

  14. 2013 IREP Symposium-Bulk Power System Dynamics and Control IX (IREP), August 25-30, 2013, Rethymnon, Greece A Production Simulation Tool for Systems with an Integrated Concentrated Solar

    E-Print Network [OSTI]

    Gross, George

    , Rethymnon, Greece A Production Simulation Tool for Systems with an Integrated Concentrated Solar Plant2013 IREP Symposium-Bulk Power System Dynamics and Control ­IX (IREP), August 25-30, 2013 with Thermal Energy Storage Ti Xu George Gross University of Illinois at Urbana-Champaign University

  15. DLFM library tools for large scale dynamic applications.

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    DLFM library tools for large scale dynamic applications DLFM library tools for large scale dynamic applications Large scale Python and other dynamic applications may spend huge...

  16. Development of Design and Simulation Tool for Hybrid Geothermal...

    Broader source: Energy.gov (indexed) [DOE]

    Development of Design and Simulation Tool for Hybrid Geothermal Heat Pump System Development of Design and Simulation Tool for Hybrid Geothermal Heat Pump System This project will...

  17. Debris Disk Radiative Transfer Simulation Tool (DDS)

    E-Print Network [OSTI]

    S. Wolf; L. A. Hillenbrand

    2005-06-17T23:59:59.000Z

    A WWW interface for the simulation of spectral energy distributions of optically thin dust configurations with an embedded radiative source is presented. The density distribution, radiative source, and dust parameters can be selected either from an internal database or defined by the user. This tool is optimized for studying circumstellar debris disks where large grains are expected to determine the far-infrared through millimeter dust reemission spectral energy distribution. The tool is available at http://aida28.mpia-hd.mpg.de/~swolf/dds

  18. A Smart Home Simulation Tool The Development of a Simulation Tool for Measuring

    E-Print Network [OSTI]

    resources such as wind turbines and solar panels. The key focus areas of the developed simulation tool prices that vary during the day based on the energy available. In order to motivate people to shift of simulating the effects of varying energy prices in private homes. Therefore this thesis develops a prototype

  19. SPINEVOLUTION: A powerful tool for the simulation of solid and liquid state NMR experiments

    E-Print Network [OSTI]

    Griffin, Robert G.

    SPINEVOLUTION: A powerful tool for the simulation of solid and liquid state NMR experiments Mikhail and dynamic information from the spectra. Simulations of solid-state magic angle spinning (MAS) experiments for the simulation of experiments with complex pulse sequences and multi-spin systems in solids, SPINEVO- LUTION

  20. A Groundwater Dynamic Simulation Model: Application to the Upper San Pedro Basin

    E-Print Network [OSTI]

    Fay, Noah

    A Groundwater Dynamic Simulation Model: Application to the Upper San Pedro Basin Report Prepared by using tools such as tracers to determine groundwater travel times and this dynamic simulation modeling

  1. Design tools for complex dynamic security systems.

    SciTech Connect (OSTI)

    Byrne, Raymond Harry; Rigdon, James Brian; Rohrer, Brandon Robinson; Laguna, Glenn A.; Robinett, Rush D. III (.; ); Groom, Kenneth Neal; Wilson, David Gerald; Bickerstaff, Robert J.; Harrington, John J.

    2007-01-01T23:59:59.000Z

    The development of tools for complex dynamic security systems is not a straight forward engineering task but, rather, a scientific task where discovery of new scientific principles and math is necessary. For years, scientists have observed complex behavior but have had difficulty understanding it. Prominent examples include: insect colony organization, the stock market, molecular interactions, fractals, and emergent behavior. Engineering such systems will be an even greater challenge. This report explores four tools for engineered complex dynamic security systems: Partially Observable Markov Decision Process, Percolation Theory, Graph Theory, and Exergy/Entropy Theory. Additionally, enabling hardware technology for next generation security systems are described: a 100 node wireless sensor network, unmanned ground vehicle and unmanned aerial vehicle.

  2. Modeling Molecular Dynamics from Simulations

    SciTech Connect (OSTI)

    Hinrichs, Nina Singhal (University of Chicago) [University of Chicago

    2009-01-28T23:59:59.000Z

    Many important processes in biology occur at the molecular scale. A detailed understanding of these processes can lead to significant advances in the medical and life sciences. For example, many diseases are caused by protein aggregation or misfolding. One approach to studying these systems is to use physically-based computational simulations to model the interactions and movement of the molecules. While molecular simulations are computationally expensive, it is now possible to simulate many independent molecular dynamics trajectories in a parallel fashion by using super- or distributed- computing methods such as Folding@Home or Blue Gene. The analysis of these large, high-dimensional data sets presents new computational challenges. In this seminar, I will discuss a novel approach to analyzing large ensembles of molecular dynamics trajectories to generate a compact model of the dynamics. This model groups conformations into discrete states and describes the dynamics as Markovian, or history-independent, transitions between the states. I will discuss why the Markovian state model (MSM) is suitable for macromolecular dynamics, and how it can be used to answer many interesting and relevant questions about the molecular system. I will also discuss many of the computational and statistical challenges in building such a model, such as how to appropriately cluster conformations, determine the statistical reliability, and efficiently design new simulations.

  3. adaptive simulation tool: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    tools used for planning, design and supervision of power plants. Using the example of the power plant simulation system Ebsilon Professional, which is established in the market...

  4. Analysis of the influence of tool dynamics in diamond turning

    SciTech Connect (OSTI)

    Fawcett, S.C.; Luttrell, D.E.; Keltie, R.F.

    1988-12-01T23:59:59.000Z

    This report describes the progress in defining the role of machine and interface dynamics on the surface finish in diamond turning. It contains a review of literature from conventional and diamond machining processes relating tool dynamics, material interactions and tool wear to surface finish. Data from experimental measurements of tool/work piece interface dynamics are presented as well as machine dynamics for the DTM at the Center.

  5. Accelerated Molecular Dynamics Simulation of Thermal Desorption.

    E-Print Network [OSTI]

    Becker, Kelly

    2008-01-01T23:59:59.000Z

    ??Desorption is a process ubiquitous in phenomena involving surfaces. However, it has rarely been simulated on the molecular level. Molecular dynamics simulation can provide the… (more)

  6. Improving Dynamic Load and Generator Response PerformanceTools

    SciTech Connect (OSTI)

    Lesieutre, Bernard C.

    2005-11-01T23:59:59.000Z

    This report is a scoping study to examine research opportunities to improve the accuracy of the system dynamic load and generator models, data and performance assessment tools used by CAISO operations engineers and planning engineers, as well as those used by their counterparts at the California utilities, to establish safe operating margins. Model-based simulations are commonly used to assess the impact of credible contingencies in order to determine system operating limits (path ratings, etc.) to ensure compliance with NERC and WECC reliability requirements. Improved models and a better understanding of the impact of uncertainties in these models will increase the reliability of grid operations by allowing operators to more accurately study system voltage problems and the dynamic stability response of the system to disturbances.

  7. DHARMA: A Tool for Evaluating Dynamic Scheduling Algorithms for Realtime Multiprocessor Systems

    E-Print Network [OSTI]

    Manimaran, Govindarasu

    , and the related issues of fault­tolerance and resource reclaiming. Section 3 reviews the earlier work on dynamic scheduling algorithms. In Section 4, we discuss our dynamic scheduling and reclaiming algorithms. Section 5 simulation results obtained using the tool are presented in Section 6 and in Section 7, some concluding

  8. Web Based Simulations for Virtual Scientific Experiment: Methodology and Tools

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    . These are the keywords. Web based simulation, Virtual Scientific Experiment, e-learning 1. INTRODUCTION Until now Technology for Enhanced Learning 1 #12;Web Based Simulations for Virtual Scientific Experiment: MethodologyWeb Based Simulations for Virtual Scientific Experiment: Methodology and Tools Giovannina Albano

  9. New Automotive Air Conditioning System Simulation Tool Developed in MATLAB/Simulink

    SciTech Connect (OSTI)

    Kiss, T.; Chaney, L.; Meyer, J.

    2013-07-01T23:59:59.000Z

    Further improvements in vehicle fuel efficiency require accurate evaluation of the vehicle's transient total power requirement. When operated, the air conditioning (A/C) system is the largest auxiliary load on a vehicle; therefore, accurate evaluation of the load it places on the vehicle's engine and/or energy storage system is especially important. Vehicle simulation software, such as 'Autonomie,' has been used by OEMs to evaluate vehicles' energy performance. A transient A/C simulation tool incorporated into vehicle simulation models would also provide a tool for developing more efficient A/C systems through a thorough consideration of the transient A/C system performance. The dynamic system simulation software Matlab/Simulink was used to develop new and more efficient vehicle energy system controls. The various modeling methods used for the new simulation tool are described in detail. Comparison with measured data is provided to demonstrate the validity of the model.

  10. The simulation of free surface flows with Computational Fluid Dynamics B. Godderidge1

    E-Print Network [OSTI]

    1 The simulation of free surface flows with Computational Fluid Dynamics B. Godderidge1 A of these applications make their simulation with computational fluid dynamics particularly challenging. The successful Computational fluid dynamics is a powerful and versatile tool for the analysis of flow problems encountered

  11. Molecular dynamics simulation of threshold displacement energies...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    experimental estimates in ceramics. Citation: Moreira PA, R Devanathan, J Yu, and WJ Weber.2009."Molecular dynamics simulation of threshold displacement energies in...

  12. Molecular dynamics simulation studies of electrolytes andelectrolyte...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. es40smith.pdf More Documents & Publications Molecular Dynamics Simulation Studies of...

  13. Molecular Dynamics Simulation of the AgCl/Electrolyte Interfacial...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Simulation of the AgClElectrolyte Interfacial Capacity. Molecular Dynamics Simulation of the AgClElectrolyte Interfacial Capacity. Abstract: Molecular dynamics simulation of the...

  14. DEMAND SIMULATION FOR DYNAMIC TRAFFIC ASSIGNMENT

    E-Print Network [OSTI]

    Bierlaire, Michel

    of the response of travelers to real-time pre- trip information. The demand simulator is an extension of dynamicDEMAND SIMULATION FOR DYNAMIC TRAFFIC ASSIGNMENT Constantinos Antoniou, Moshe Ben-Akiva, Michel Bierlaire, and Rabi Mishalani Massachusetts Institute of Technology, Cambridge, MA 02139 Abstract

  15. Model Validation with Hybrid Dynamic Simulation

    SciTech Connect (OSTI)

    Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.

    2006-06-18T23:59:59.000Z

    Abstract—Model validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation.

  16. VALIDATION OF MASSIVELY PARALLEL SIMULATIONS OF DYNAMIC FRACTURE AND

    E-Print Network [OSTI]

    Barr, Al

    VALIDATION OF MASSIVELY PARALLEL SIMULATIONS OF DYNAMIC FRACTURE AND FRAGMENTATION OF BRITTLE element simulations of dynamic fracture and fragmentation of brittle solids are presented. Fracture the results of massively parallel numerical simulations of dynamic fracture and fragmentation in brittle

  17. Molecular dynamics simulation and ab intio studies of electrolytes...

    Broader source: Energy.gov (indexed) [DOE]

    Molecular dynamics simulation and ab intio studies of electrolytes and electrolyteelectrode interfaces Molecular dynamics simulation and ab intio studies of electrolytes and...

  18. Atomic detail brownian dynamics simulations of concentrated protein...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    detail brownian dynamics simulations of concentrated protein solutions with a mean field treatment of hydrodynamic Atomic detail brownian dynamics simulations of concentrated...

  19. Molecular Dynamics Simulation of Macromolecules Using Graphics Processing Unit

    E-Print Network [OSTI]

    Ji Xu; Ying Ren; Wei Ge; Xiang Yu; Xiaozhen Yang; Jinghai Li

    2010-01-21T23:59:59.000Z

    Molecular dynamics (MD) simulation is a powerful computational tool to study the behavior of macromolecular systems. But many simulations of this field are limited in spatial or temporal scale by the available computational resource. In recent years, graphics processing unit (GPU) provides unprecedented computational power for scientific applications. Many MD algorithms suit with the multithread nature of GPU. In this paper, MD algorithms for macromolecular systems that run entirely on GPU are presented. Compared to the MD simulation with free software GROMACS on a single CPU core, our codes achieve about 10 times speed-up on a single GPU. For validation, we have performed MD simulations of polymer crystallization on GPU, and the results observed perfectly agree with computations on CPU. Therefore, our single GPU codes have already provided an inexpensive alternative for macromolecular simulations on traditional CPU clusters and they can also be used as a basis to develop parallel GPU programs to further speedup the computations.

  20. RTSTEP regional transportation simulation tool for emergency planning - final report.

    SciTech Connect (OSTI)

    Ley, H.; Sokolov, V.; Hope, M.; Auld, J.; Zhang, K.; Park, Y.; Kang, X. (Energy Systems)

    2012-01-20T23:59:59.000Z

    Large-scale evacuations from major cities during no-notice events - such as chemical or radiological attacks, hazardous material spills, or earthquakes - have an obvious impact on large regions rather than on just the directly affected area. The scope of impact includes the accommodation of emergency evacuation traffic throughout a very large area; the planning of resources to respond appropriately to the needs of the affected population; the placement of medical supplies and decontamination equipment; and the assessment and determination of primary escape routes, as well as routes for incoming emergency responders. Compared to events with advance notice, such as evacuations based on hurricanes approaching an affected area, the response to no-notice events relies exclusively on pre-planning and general regional emergency preparedness. Another unique issue is the lack of a full and immediate understanding of the underlying threats to the population, making it even more essential to gain extensive knowledge of the available resources, the chain of command, and established procedures. Given the size of the area affected, an advanced understanding of the regional transportation systems is essential to help with the planning for such events. The objectives of the work described here (carried out by Argonne National Laboratory) is the development of a multi-modal regional transportation model that allows for the analysis of different evacuation scenarios and emergency response strategies to build a wealth of knowledge that can be used to develop appropriate regional emergency response plans. The focus of this work is on the effects of no-notice evacuations on the regional transportation network, as well as the response of the transportation network to the sudden and unusual demand. The effects are dynamic in nature, with scenarios changing potentially from minute to minute. The response to a radiological or chemical hazard will be based on the time-delayed dispersion of such materials over a large area, with responders trying to mitigate the immediate danger to the population in a variety of ways that may change over time (e.g., in-place evacuation, staged evacuations, and declarations of growing evacuation zones over time). In addition, available resources will be marshaled in unusual ways, such as the repurposing of transit vehicles to support mass evacuations. Thus, any simulation strategy will need to be able to address highly dynamic effects and will need to be able to handle any mode of ground transportation. Depending on the urgency and timeline of the event, emergency responders may also direct evacuees to leave largely on foot, keeping roadways as clear as possible for emergency responders, logistics, mass transport, and law enforcement. This RTSTEP project developed a regional emergency evacuation modeling tool for the Chicago Metropolitan Area that emergency responders can use to pre-plan evacuation strategies and compare different response strategies on the basis of a rather realistic model of the underlying complex transportation system. This approach is a significant improvement over existing response strategies that are largely based on experience gained from small-scale events, anecdotal evidence, and extrapolation to the scale of the assumed emergency. The new tool will thus add to the toolbox available to emergency response planners to help them design appropriate generalized procedures and strategies that lead to an improved outcome when used during an actual event.

  1. Molecular Dynamics Simulations of Supported Pt Nanoclusters

    E-Print Network [OSTI]

    Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

    ¤Introduction and Background ¤Constructing a Physical Model ¤Details of the Simulation ¤Results and Conclusions · Petroleum reformation · Gasification of biomass for biofuels #12;Previous Investigation of NanoclustersMolecular Dynamics Simulations of Supported Pt Nanoclusters Jeffrey Moore #12;A Brief Outline

  2. Physical simulation study of dynamic voltage instability

    SciTech Connect (OSTI)

    Tso, S.K.; Zhu, T.X. [Univ. of Hong Kong (Hong Kong); Zeng, Q.Y. [Electric Power Research Inst., Beijing (China); Lo, K.L. [Univ. of Strathclyde, Glasgow (United Kingdom). Dept. of Electrical and Electrical Engineering

    1995-12-31T23:59:59.000Z

    This paper presents a physical simulation of the dynamic behavior of voltage instability in an interconnected multimachine environment. The dynamic evolving process leading to eventual voltage collapse, the scenario of the progressive reactive support reduction resulting from the MXL protection relays, the OLTC operation, and the effect of switched-in capacitor banks are examined using physical facilities in the laboratory. The physical simulation results are also compared with digital simulation results. This physical investigation provides a reliable foundation for the effective development of assessment approaches and countermeasures.

  3. Monte Carlo Simulation Tool Installation and Operation Guide

    SciTech Connect (OSTI)

    Aguayo Navarrete, Estanislao; Ankney, Austin S.; Berguson, Timothy J.; Kouzes, Richard T.; Orrell, John L.; Troy, Meredith D.; Wiseman, Clinton G.

    2013-09-02T23:59:59.000Z

    This document provides information on software and procedures for Monte Carlo simulations based on the Geant4 toolkit, the ROOT data analysis software and the CRY cosmic ray library. These tools have been chosen for its application to shield design and activation studies as part of the simulation task for the Majorana Collaboration. This document includes instructions for installation, operation and modification of the simulation code in a high cyber-security computing environment, such as the Pacific Northwest National Laboratory network. It is intended as a living document, and will be periodically updated. It is a starting point for information collection by an experimenter, and is not the definitive source. Users should consult with one of the authors for guidance on how to find the most current information for their needs.

  4. Selector: A tool for dynamic service selection and management

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -awareness while discovering and selecting web service. The main idea of the proposed web service oriented architecture consists in the ontology Context-aware Quality Semantic Web Service called (CxQWS). At the firstSelector: A tool for dynamic service selection and management ALTI Adel, BOUKERRAM Abdallah, ROOSE

  5. New Simulation Tool Could Help Add More Solar to the Nation¹s...

    Broader source: Energy.gov (indexed) [DOE]

    Simulation Tool Could Help Add More Solar to the Nations Electric Grid New Simulation Tool Could Help Add More Solar to the Nations Electric Grid April 17, 2014 - 11:26am...

  6. Application of Various HVAC Simulation Programs and Visual Tools to Commissioning

    E-Print Network [OSTI]

    Zheng, M.; Pan, S.

    2007-01-01T23:59:59.000Z

    Various existing HVAC system simulation programs and visualization tools are considered to be potentially powerful tools for commissioning. Although not originally developed as commissioning tools, these programs facilitate the confirmation...

  7. Simulating the Effect of Modulated Tool-Path Chip Breaking On Surface Texture and Chip Length

    SciTech Connect (OSTI)

    Smith, K.S.; McFarland, J.T.; Tursky, D. A.; Assaid, T. S.; Barkman, W. E.; Babelay, Jr., E. F.

    2010-04-30T23:59:59.000Z

    One method for creating broken chips in turning processes involves oscillating the cutting tool in the feed direction utilizing the CNC machine axes. The University of North Carolina at Charlotte and the Y-12 National Security Complex have developed and are refining a method to reliably control surface finish and chip length based on a particular machine's dynamic performance. Using computer simulations it is possible to combine the motion of the machine axes with the geometry of the cutting tool to predict the surface characteristics and map the surface texture for a wide range of oscillation parameters. These data allow the selection of oscillation parameters to simultaneously ensure broken chips and acceptable surface characteristics. This paper describes the machine dynamic testing and characterization activities as well as the computational method used for evaluating and predicting chip length and surface texture.

  8. CgWind: A high-order accurate simulation tool for wind turbines and wind farms

    SciTech Connect (OSTI)

    Chand, K K; Henshaw, W D; Lundquist, K A; Singer, M A

    2010-02-22T23:59:59.000Z

    CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

  9. Westinghouse Waste Simulation and Optimization Software Tool - 13493

    SciTech Connect (OSTI)

    Mennicken, Kim [Westinghouse Electric Germany GmbH, Global Waste Management, Dudenstrasse 44, D-68167 Mannheim (Germany)] [Westinghouse Electric Germany GmbH, Global Waste Management, Dudenstrasse 44, D-68167 Mannheim (Germany); Aign, Joerg [Westinghouse Electric Germany GmbH, Global Waste Management, Tarpenring 6, D-22419 Hamburg (Germany)] [Westinghouse Electric Germany GmbH, Global Waste Management, Tarpenring 6, D-22419 Hamburg (Germany)

    2013-07-01T23:59:59.000Z

    Radioactive waste is produced during NPP operation and NPP D and D. Different kinds of waste with different volumes and properties have to be treated. Finding a technically and commercially optimized waste treatment concept is a difficult and time consuming process. The Westinghouse waste simulation and optimization software tool is an approach to study the total life cycle cost of any waste management facility. The tool enables the user of the simulation and optimization software to plan processes and storage buildings and to identify bottlenecks in the overall waste management design before starting detailed planning activities. Furthermore, application of the software enables the user to optimize the number of treatment systems, to determine the minimum design capacity for onsite storage facilities, to identify bottlenecks in the overall design and to identify the most cost-effective treatment paths by maintaining optimal waste treatment technologies. In combination with proven waste treatment equipment and integrated waste management solutions, the waste simulation and optimization software provides reliable qualitative results that lead to an effective planning and minimization of the total project planning risk of any waste management activity. (authors)

  10. A Simulation Tool for Analysis of Alternative Paradigms for the New Electricity Business

    E-Print Network [OSTI]

    A Simulation Tool for Analysis of Alternative Paradigms for the New Electricity Business Thomas J preliminary results on the development of a simulation tool to perform this analysis. Since power systems are ultimately governed by the laws of physics, the heart of the tool is a power system simulation engine, valid

  11. A SOFTWARE TOOL TO COMPARE MEASURED AND SIMULATED BUILDING ENERGY PERFORMANCE

    E-Print Network [OSTI]

    LBNL-6184E A SOFTWARE TOOL TO COMPARE MEASURED AND SIMULATED BUILDING ENERGY PERFORMANCE DATA of California. #12;A SOFTWARE TOOL TO COMPARE MEASURED AND SIMULATED BUILDING ENERGY PERFORMANCE DATA Tobias and simulated performance data. In context of this method, we developed a software tool that provides graphing

  12. Dynamic procedure for filtered gyrokinetic simulations

    SciTech Connect (OSTI)

    Morel, P.; Banon Navarro, A.; Albrecht-Marc, M.; Carati, D. [Statistical and Plasma Physics Laboratory, Universite Libre de Bruxelles, Bruxelles 1050 (Belgium); Merz, F.; Goerler, T.; Jenko, F. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)

    2012-01-15T23:59:59.000Z

    Large eddy simulations (LES) of gyrokinetic plasma turbulence are investigated as interesting candidates to decrease the computational cost. A dynamic procedure is implemented in the gene code, allowing for dynamic optimization of the free parameters of the LES models (setting the amplitudes of dissipative terms). Employing such LES methods, one recovers the free energy and heat flux spectra obtained from highly resolved direct numerical simulations. Systematic comparisons are performed for different values of the temperature gradient and magnetic shear, parameters which are of prime importance in ion temperature gradient driven turbulence. Moreover, the degree of anisotropy of the problem, which can vary with parameters, can be adapted dynamically by the method that shows gyrokinetic large eddy simulation to be a serious candidate to reduce numerical cost of gyrokinetic solvers.

  13. Eddy current NDE performance demonstrations using simulation tools

    SciTech Connect (OSTI)

    Maurice, L. [EDF - CEIDRE, 2 rue Ampere, 93206 Saint-Denis Cedex 1 (France); Costan, V.; Guillot, E.; Thomas, P. [EDF - R and D, THEMIS, 1, avenue du General de Gaulle, 92141 Clamart (France)

    2013-01-25T23:59:59.000Z

    To carry out performance demonstrations of the Eddy-Current NDE processes applied on French nuclear power plants, EDF studies the possibility of using simulation tools as an alternative to measurements on steam generator tube mocks-up. This paper focuses on the strategy led by EDF to assess and use code{sub C}armel3D and Civa, on the case of Eddy-Current NDE on wears problem which may appear in the U-shape region of steam generator tubes due to the rubbing of anti-vibration bars.

  14. A visual simulation playground for engineering dynamics

    E-Print Network [OSTI]

    Fong, Donald Brian

    2008-10-10T23:59:59.000Z

    A VISUAL SIMULATION PLAYGROUND FOR ENGINEERING DYNAMICS A Thesis by DONALD BRIAN FONG Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER OF SCIENCE August 2008 Major... Subject: Visualization Sciences A VISUAL SIMULATION PLAYGROUND FOR ENGINEERING DYNAMICS A Thesis by DONALD BRIAN FONG Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER...

  15. Model Validation with Hybrid Dynamic Simulation

    SciTech Connect (OSTI)

    Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.

    2006-06-22T23:59:59.000Z

    Abstract—Model validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation. A few methods to define model quality indices have been proposed to quantify model error for model validation criteria development.

  16. Battery Lifetime Analysis and Simulation Tool (BLAST) Documentation

    SciTech Connect (OSTI)

    Neubauer, J.

    2014-12-01T23:59:59.000Z

    The deployment and use of lithium-ion batteries in automotive and stationary energy storage applications must be optimized to justify their high up-front costs. Given that batteries degrade with use and storage, such optimizations must evaluate many years of operation. As the degradation mechanisms are sensitive to temperature, state-of-charge histories, current levels, and cycle depth and frequency, it is important to model both the battery and the application to a high level of detail to ensure battery response is accurately predicted. To address these issues, the National Renewable Energy Laboratory has developed the Battery Lifetime Analysis and Simulation Tool (BLAST) suite of tools. This suite of tools pairs NREL's high-fidelity battery degradation model with a battery electrical and thermal performance model, application-specific electrical and thermal performance models of the larger system (e.g., an electric vehicle), application-specific system use data (e.g., vehicle travel patterns and driving data), and historic climate data from cities across the United States. This provides highly realistic, long-term predictions of battery response and thereby enables quantitative comparisons of varied battery use strategies.

  17. Building design and thermal renovation measures proposal by means of regression models issued from dynamic simulations

    E-Print Network [OSTI]

    Boyer, Edmond

    comparison between different energy reduction strategies, like improving the insulation levels or increasing the thermal inertia. An example of their use and a data comparison with a dynamic simulation is shown in last;Nowadays, the most reliable solutions to calculate the energy demand are the simulation energy tools

  18. Dynamic simulation of a reverse Brayton refrigerator

    SciTech Connect (OSTI)

    Peng, N.; Xiong, L. Y.; Dong, B.; Liu, L. Q. [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, CAS, Beijing, 100190 (China); Lei, L. L.; Tang, J. C. [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, CAS, Beijing, 100190 China and Graduate University of Chinese Academy of Sciences, Beijing, 100190 (China)

    2014-01-29T23:59:59.000Z

    A test refrigerator based on the modified Reverse Brayton cycle has been developed in the Chinese Academy of Sciences recently. To study the behaviors of this test refrigerator, a dynamic simulation has been carried out. The numerical model comprises the typical components of the test refrigerator: compressor, valves, heat exchangers, expander and heater. This simulator is based on the oriented-object approach and each component is represented by a set of differential and algebraic equations. The control system of the test refrigerator is also simulated, which can be used to optimize the control strategies. This paper describes all the models and shows the simulation results. Comparisons between simulation results and experimental data are also presented. Experimental validation on the test refrigerator gives satisfactory results.

  19. Simulating Field-Scale Soil Organic Carbon Dynamics Using EPIC

    SciTech Connect (OSTI)

    Causarano, Hector J.; Shaw, Joey N.; Franzluebbers, A. J.; reeves, D. W.; Raper, Randy L.; Balkcom, Kipling S.; Norfleet, M. L.; Izaurralde, R Cesar

    2007-07-01T23:59:59.000Z

    Simulation models integrate our knowledge of soil organic C (SOC) dynamics and are useful tools for evaluating impacts of crop management on soil C sequestration; yet, they require local calibration. Our objectives were to calibrate the Environmental Policy Integrated Climate (EPIC) model, and evaluate its performance for simulating SOC fractions as affected by soil landscape and management. An automated parameter optimization procedure was used to calibrate the model for a site-specific experiment in the Coastal Plain of central Alabama. The ability of EPIC to predict corn (Zea mays L.) and cotton (Gossypium hirsutum L.) yields and SOC dynamics on different soil landscape positions (summit, sideslope and drainageway) during the initial period of conservation tillage adoption (5 years) was evaluated using regression and mean squared deviations. Simulated yield explained 88% of measured yield variation, with greatest disagreement on the sideslope position and highest agreement in the drainageway. Simulations explained approximately 1, 34 and 40% of the total variation in microbial biomass C (MBC), particulate organic C (POC) and total organic C (TOC), respectively. Lowest errors on TOC simulations (0-20 cm) were found on the sideslope and summit. We conclude that the automated parameterization was generally successful, although further work is needed to refine the MBC and POC fractions, and to improve EPIC predictions of SOC dynamics with depth. Overall, EPIC was sensitive to spatial differences in C fractions that resulted from differing soil landscape positions. The model needs additional refinement for accurate simulations of field-scale SOC dynamics affected by short-term management decisions.

  20. Simulation of plasmaneutral dynamics for radiation cooling

    E-Print Network [OSTI]

    Najmabadi, Farrokh

    the heat flux effectively for future power plants. That is, radiation due to impurities will lower and increase the required pumping speed con- siderably in a power plant. In principle, the plasma energySimulation of plasma­neutral dynamics for radiation cooling Bong Ju Lee , F. Najmabadi Fusion

  1. 2. Unit Operation Dynamic simulation Unit operation

    E-Print Network [OSTI]

    Hong, Deog Ki

    specification . 2.2 Heat transfer equipment Air cooler, cooler/heater, heat exchanger, fired heater LNG multi flow heat exchanger . 2.3 Piping equipment Mixer, tee, pipe, gas pipe, valve, relief valve . 2.4 Rotating equipment Centrifugal compressor or expander, reciprocating compressor pump ,dynamic simulation

  2. Dynamic simulation of polyester mooring lines

    E-Print Network [OSTI]

    Kim, Min Suk

    2004-09-30T23:59:59.000Z

    A numerical scheme, known as CABLE3D, originally developed for the simulation of dynamics of steel chain-wire mooring lines is extended to allow for the large elongation in a mooring line, the dependence of the modulus on tension, and energy...

  3. A Framework like a tool for specify motivating Collaborative Learning Participatory Simulations

    E-Print Network [OSTI]

    Antunes, Pedro

    1 A Framework like a tool for specify motivating Collaborative Learning Participatory Simulations that collaborative participatory simulations improve teaching and learning, increasing motivation inside. Keywords: Handhelds. Gestures, Sketches. Collaborative Learning. Participatory Simulation. 1. Introduction

  4. Molecular dynamics simulation of hydration in myoglobin

    SciTech Connect (OSTI)

    Gu, Wei [New Mexico Univ., Albuquerque, NM (United States). Dept. of Biochemistry; Schoenborn, B.P. [Los Alamos National Lab., NM (United States)

    1995-09-01T23:59:59.000Z

    This study was carried out to evaluate the stability of the 89 bound water molecules that were observed in the neutron diffraction study of CO myoglobin. The myoglobin structure derived from the neutron analysis was used as the starting point in the molecular dynamics simulation using the software package CHARMM. After salvation of the protein, energy minimization and equilibration of the system, 50 pico seconds of Newtonian dynamics was performed. This data showed that only 4 water molecules are continously bound during the length of this simulation while the other solvent molecules exhibit considerable mobility and are breaking and reforming hydrogen bonds with the protein. At any instant during the simulation, 73 of the hydration sites observed in the neutron structure are occupied by water.

  5. Perturbation centrality: a novel centrality measure obtained by the general network dynamics tool, Turbine

    E-Print Network [OSTI]

    Szalay, Kristof Z

    2013-01-01T23:59:59.000Z

    Analysis of network dynamics became increasingly important to understand the mechanisms and consequences of changes in biological systems from macromolecules to cells and organisms. Currently available network dynamics tools are mostly tailored for specific tasks such as calculation of molecular or neural dynamics. Our Turbine software offers a generic framework enabling the simulation of any algorithmically definable dynamics of any network. Turbine is also optimized for handling very large networks in the range of millions of nodes and edges. Using a perturbation transmission model inspired by communicating vessels, here we introduce a novel centrality measure termed as perturbation centrality. Perturbation centrality is the reciprocal of the time needed to dissipate a starting perturbation in the network. Hubs and inter-modular nodes proved to be highly efficient in perturbation propagation. High perturbation centrality nodes of the Met-tRNA synthetase protein structure network were identified as amino aci...

  6. Simulation of Complex Fluids using Dissipative Particle Dynamics

    E-Print Network [OSTI]

    ... Dynamics Abstract: Dissipative Particle Dynamics (DPD) is a relatively new mesoscopic method particularly suitable for simulating biopolymers. It is a coarsed ...

  7. Molecular dynamics simulation and ab intio studies of electrolytes...

    Broader source: Energy.gov (indexed) [DOE]

    DFT calculations on molecular clusters and electrode surfaces, reactive molecular dynamics simulations allowing modeling of SEI formation, and classical molecular dynamics...

  8. Molecular dynamics simulations of ion range profiles for heavy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    simulations of ion range profiles for heavy ions in light targets. Molecular dynamics simulations of ion range profiles for heavy ions in light targets. Abstract: The determination...

  9. Molecular Dynamics Simulations of Uranyl and Uranyl Carbonate...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Simulations of Uranyl and Uranyl Carbonate Adsorption at Alumino-silicate Surfaces. Molecular Dynamics Simulations of Uranyl and Uranyl Carbonate Adsorption at Alumino-silicate...

  10. Computer Simulation of Quantum Dynamics in a Classical Spin Environment

    E-Print Network [OSTI]

    Alessandro Sergi

    2014-04-24T23:59:59.000Z

    In this paper a formalism for studying the dynamics of quantum systems coupled to classical spin environments is reviewed. The theory is based on generalized antisymmetric brackets and naturally predicts open-path off-diagonal geometric phases in the evolution of the density matrix. It is shown that such geometric phases must also be considered in the quantum-classical Liouville equation for a classical bath with canonical phase space coordinates; this occurs whenever the adiabatics basis is complex (as in the case of a magnetic field coupled to the quantum subsystem). When the quantum subsystem is weakly coupled to the spin environment, non-adiabatic transitions can be neglected and one can construct an effective non-Markovian computer simulation scheme for open quantum system dynamics in classical spin environments. In order to tackle this case, integration algorithms based on the symmetric Trotter factorization of the classical-like spin propagator are derived. Such algorithms are applied to a model comprising a quantum two-level system coupled to a single classical spin in an external magnetic field. Starting from an excited state, the population difference and the coherences of this two-state model are simulated in time while the dynamics of the classical spin is monitored in detail. It is the author's opinion that the numerical evidence provided in this paper is a first step toward developing the simulation of quantum dynamics in classical spin environments into an effective tool. In turn, the ability to simulate such a dynamics can have a positive impact on various fields, among which, for example, nano-science.

  11. Physics results from dynamical overlap fermion simulations

    E-Print Network [OSTI]

    Shoji Hashimoto

    2008-11-08T23:59:59.000Z

    I summarize the physics results obtained from large-scale dynamical overlap fermion simulations by the JLQCD and TWQCD collaborations. The numerical simulations are performed at a fixed global topological sector; the physics results in the theta-vacuum is reconstructed by correcting the finite volume effect, for which the measurement of the topological susceptibility is crucial. Physics applications we studied so far include a calculation of chiral condensate, pion mass, decay constant, form factors, as well as (vector and axial-vector) vacuum polarization functions and nucleon sigma term.

  12. A versatile simulation tool for the design and verification of military vehicle power systems

    E-Print Network [OSTI]

    Lipscomb, Melissa Anne

    2005-11-01T23:59:59.000Z

    modes of operation and system scenarios) and system performance in a dynamic, realistic environment. This thesis proposes a new tool to analyze and design military vehicle platforms: the Advanced Mobile Integrated Power System (AMPS). This tool is useful...

  13. Activity-based costing simulation as a tool for construction process optimization

    E-Print Network [OSTI]

    Son, Junghye

    1999-01-01T23:59:59.000Z

    to develop the scope of time-cost optimization in this research. Optimization tools, such as neural networks, genetic algorithms, and simulation methods were analyzed to determine an effective tool for the optimization based on the planning and execution...

  14. Using Product Specific Simulation Models in a Tool for Manual Commissioning of Air Handling Units

    E-Print Network [OSTI]

    Eriksson, J.

    2003-01-01T23:59:59.000Z

    This short paper describes an outline of a tool for manual commissioning of air handling units. The prototype tool is implemented EES professional version that can generate standalone programs. The idea is to use the benefit of simulation models...

  15. NREL Developing a Numerical Simulation Tool to Study Hydrokinetic Energy Conversion Devices and Arrays (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2012-02-01T23:59:59.000Z

    New code will help accelerate design improvements by providing a high-fidelity simulation tool to study power performance, structural loading, and the interactions between devices in arrays.

  16. Ice-Floe Simulation Viewer Tool Justin Adams

    E-Print Network [OSTI]

    Peters, Dennis

    such as Google Sketchup so that new users feel comfortable when utilizing the tool. Figure 1 shows a screenshot

  17. Co-Simulation Tools for Networked Control Systems

    E-Print Network [OSTI]

    Branicky, Michael S.

    Modelica and ns-2. For each tool, we present demonstrative case studies that highlight its capabilities. 1

  18. Method and apparatus for characterizing and enhancing the dynamic performance of machine tools

    DOE Patents [OSTI]

    Barkman, William E; Babelay, Jr., Edwin F

    2013-12-17T23:59:59.000Z

    Disclosed are various systems and methods for assessing and improving the capability of a machine tool. The disclosure applies to machine tools having at least one slide configured to move along a motion axis. Various patterns of dynamic excitation commands are employed to drive the one or more slides, typically involving repetitive short distance displacements. A quantification of a measurable merit of machine tool response to the one or more patterns of dynamic excitation commands is typically derived for the machine tool. Examples of measurable merits of machine tool performance include dynamic one axis positional accuracy of the machine tool, dynamic cross-axis stability of the machine tool, and dynamic multi-axis positional accuracy of the machine tool.

  19. Brownian Dynamics Simulation of Protein Solutions: Structural and Dynamical Properties

    SciTech Connect (OSTI)

    Mereghetti, Paolo; Gabdoulline, Razif; Wade, Rebecca C.

    2010-12-01T23:59:59.000Z

    The study of solutions of biomacromolecules provides an important basis for understanding the behavior of many fundamental cellular processes, such as protein folding, self-assembly, biochemical reactions, and signal transduction. Here, we describe a Brownian dynamics simulation procedure and its validation for the study of the dynamic and structural properties of protein solutions. In the model used, the proteins are treated as atomically detailed rigid bodies moving in a continuum solvent. The protein-protein interaction forces are described by the sum of electrostatic interaction, electrostatic desolvation, nonpolar desolvation, and soft-core repulsion terms. The linearized Poisson-Boltzmann equation is solved to compute electrostatic terms. Simulations of homogeneous solutions of three different proteins with varying concentrations, pH, and ionic strength were performed. The results were compared to experimental data and theoretical values in terms of long-time self-diffusion coefficients, second virial coefficients, and structure factors. The results agree with the experimental trends and, in many cases, experimental values are reproduced quantitatively. There are no parameters specific to certain protein types in the interaction model, and hence the model should be applicable to the simulation of the behavior of mixtures of macromolecules in cell-like crowded environments.

  20. Dynamic Simulators | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesDataTranslocationDiurnalCommitteeDurableElectronDynamic Simulators

  1. USING VIDEO FOR ANALYZING DAYLIGHT SIMULATION TOOLS Daniel C. Glaser1

    E-Print Network [OSTI]

    Varela, Carlos

    USING VIDEO FOR ANALYZING DAYLIGHT SIMULATION TOOLS Daniel C. Glaser1 , F. Whitney Smith2 , Barb socio-technical techniques can be employed to analyze video data of people using daylight simulation, a classic daylighting analysis tool; and in the second a lighting professional is asked to use a new data

  2. Computer simulations to classrooms: tools for change Noah S. Podolefsky, Katherine K. Perkins, & Wendy K. Adams

    E-Print Network [OSTI]

    Colorado at Boulder, University of

    Computer simulations to classrooms: tools for change Noah S. Podolefsky, Katherine K. Perkins-0390 Abstract. This paper situates PhET computer simulations (sims) in a socio-cultural-historical context. Sims learning through exploration. We focus on interactions between three scales of tools: representations

  3. A New Motorcycle Simulator Platform: Mechatronics Design, Dynamics Modeling

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    A New Motorcycle Simulator Platform: Mechatronics Design, Dynamics Modeling and Control L. Nehaoua of these techniques to other simulators (cars and motorcycles) is possible but not direct. Indeed, the dynamics motorcycle driving simulators were build. The first prototype was developed by Honda in 1988

  4. Development of Design and Simulation Tool for Hybrid Geothermal...

    Broader source: Energy.gov (indexed) [DOE]

    * Estimated funding for FY10 is 225,000 - Barriers * Lack of sufficient design and energy analysis tool for hybrid ground source heat pump (HGSHP) systems - Partners * James...

  5. Plasticity of metal wires in torsion: molecular dynamics and dislocation dynamics simulations

    E-Print Network [OSTI]

    Cai, Wei

    Plasticity of metal wires in torsion: molecular dynamics and dislocation dynamics simulations-4040 Abstract The orientation dependent plasticity in metal nanowires is investigated using molecular dynamics metal wires controls the mechanisms of plastic deformation. For wires oriented along 110 , dislocations

  6. Molecular dynamics simulation and ab intio studies of electrolytes...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation es058smith2011o.pdf More Documents & Publications Molecular Dynamics Simulation Studies of...

  7. Molecular Dynamics Simulation Studies of Electrolytes and Electrolyte...

    Broader source: Energy.gov (indexed) [DOE]

    and is lower than the barrier for opening EC cyclic radical. ReaxFF molecular dynamics simulations show similar barriers in gas and condensed phases for these reactions....

  8. Games, Role-Playing, Tools and Models as a Learning Process to Simulate Groundwater Management Negotiation

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Games, Role-Playing, Tools and Models as a Learning Process to Simulate Groundwater Management in answering this question at a local level. A negotiation support simulator for a regional project is proposed which includes the numerous actors involved in water resource management projects. This simulator

  9. CADS:Cantera Aerosol Dynamics Simulator.

    SciTech Connect (OSTI)

    Moffat, Harry K.

    2007-07-01T23:59:59.000Z

    This manual describes a library for aerosol kinetics and transport, called CADS (Cantera Aerosol Dynamics Simulator), which employs a section-based approach for describing the particle size distributions. CADS is based upon Cantera, a set of C++ libraries and applications that handles gas phase species transport and reactions. The method uses a discontinuous Galerkin formulation to represent the particle distributions within each section and to solve for changes to the aerosol particle distributions due to condensation, coagulation, and nucleation processes. CADS conserves particles, elements, and total enthalpy up to numerical round-off error, in all of its formulations. Both 0-D time dependent and 1-D steady state applications (an opposing-flow flame application) have been developed with CADS, with the initial emphasis on developing fundamental mechanisms for soot formation within fires. This report also describes the 0-D application, TDcads, which models a time-dependent perfectly stirred reactor.

  10. Services inside the Smart Home A Simulation and Visualization tool

    E-Print Network [OSTI]

    Aiello, Marco

    SketchUp (http://sketchup.google.com) with a set of tools that extend its visual representation as a set of plug-ins for Google SketchUp, the communication mechanism is based on the Ruby SOAP

  11. Abaqus Simulations of Rock Response to Dynamic Loading

    SciTech Connect (OSTI)

    Steedman, David W. [Los Alamos National Laboratory; Coblentz, David [Los Alamos National Laboratory

    2012-08-15T23:59:59.000Z

    The LANL Geodynamics Team has been applying Abaqus modeling to achieve increasingly complex simulations. Advancements in Abaqus model building and simulation tools allows this progress. We use Lab-developed constitutive models, the fully coupled CEL Abaqus and general contact to simulate response of realistic sites to explosively driven shock.

  12. A Dynamic Waste Isolation Pilot Plant Performance Assessment Tool - 12490

    SciTech Connect (OSTI)

    Scopatz, Anthony M.; March, Jonathan; Weckesser, Warren; Jones, Eric [Enthought Inc, Austin, Texas, 78701 (United States); Lee, Moo; Camphouse, Chris [Sandia National Laboratories, Carlsbad, NM, 88220 (United States)

    2012-07-01T23:59:59.000Z

    The Waste Isolation Pilot Plant (WIPP) Performance Assessment (PA) methodology comprises a toolbox used to demonstrate regulatory compliance of the repository after facility closure. The PA framework rests upon an extensive suite of computational codes. In some cases, significant alteration of code inputs is a tedious and difficult task. Due to the nature of the application for which they are used, PA codes used in support of WIPP regulatory compliance demonstration must satisfy stringent quality assurance requirements. Consequently, many of the coding practices used during original code development are still implemented today. A more efficient workflow configuration has the potential to alleviate difficulties associated with extensive code input modifications. Here, this potential is assessed via an implementation of a more flexible scientific workflow system for a subset of the codes used in WIPP PA. The scientific workflow approach taken here for a dynamic PA system enables users from disparate backgrounds to dramatically shorten the time between hypothesis and analysis by decreasing the amount of a priori knowledge, from a range of disciplines, needed to execute the code. Having smaller iteration times allows for more ideas to be tested and explored, which leads to safer and more optimized systems. Note that these high-level, dynamic tools are intended only for initial scoping studies on the personal computer of a researcher. Full, regulatory compliance calculations may occur only within a qualified computing environment. However, the WIPP PA tools here may guide future research and indicate regions of the analysis space that are worth further study. This next generation of PA software provides the ability to perform scoping investigations of repository performance quickly and easily, and has an accessible and useful interface to a variety of users, such as fuel cycle systems designers, domain experts such as repository modelers, and policy makers. The purview of this project allows for many opportunities for future work. Foremost among these is the desire to implement the full BRAGFLO suite within the workflow. This will entail porting or wrapping Genmesh, Matset, LHS, and ICSet within Python. Moreover, unifying the two GUIs into a single driver application would be a natural next step. Once the BRAGFLO suite is completed, other portions of WIPP PA could be implemented with corresponding and inter-operable work-flows. Likely first candidates for this are those codes that are similarly computationally intensive, such as the one used to generate complementary cumulative distribution functions used to demonstrate regulatory compliance (code CCDFGF). (authors)

  13. Parallel implementation of three-dimensional molecular dynamic simulation for laser-cluster interaction

    SciTech Connect (OSTI)

    Holkundkar, Amol R. [Department of Physics, Birla Institute of Technology and Science, Pilani-333 031 (India)] [Department of Physics, Birla Institute of Technology and Science, Pilani-333 031 (India)

    2013-11-15T23:59:59.000Z

    The objective of this article is to report the parallel implementation of the 3D molecular dynamic simulation code for laser-cluster interactions. The benchmarking of the code has been done by comparing the simulation results with some of the experiments reported in the literature. Scaling laws for the computational time is established by varying the number of processor cores and number of macroparticles used. The capabilities of the code are highlighted by implementing various diagnostic tools. To study the dynamics of the laser-cluster interactions, the executable version of the code is available from the author.

  14. A Qualitative Simulation Approach for Fuzzy Dynamical Models

    E-Print Network [OSTI]

    Bontempi, Gianluca

    .g., a nuclear power plant in unexpected emergency situations) or because if does not yet exist (eA Qualitative Simulation Approach for Fuzzy Dynamical Models ANDREA BONARINI and GIANLUCA BONTEMPI Politecnico di Milano This article deal with simulation of approximate models of dynamic systems. We propose

  15. Study of residential dehumidifiers results in practical performance curves for use in whole-building simulation tools.

    E-Print Network [OSTI]

    -building simulation tools. Dehumidifiers remove moisture from a home's indoor environment, thereby increasing occupant dehumidifier to be simulated in whole-building analysis tools. NREL researchers also defined a new, generalized determine moisture removal capacities and efficiencies.Whole-building simulation tool performance curves

  16. Computer simulation as a NOx reduction design tool

    SciTech Connect (OSTI)

    Liu, G.; Higgins, B.S. [Nalco Mobotec (United States)

    2008-10-15T23:59:59.000Z

    Nalco Mobotec engineers were charged with reducing emissions on a utility boiler converted from burning oil to eastern bituminous coal using the company's Rotamix selective noncatalytic reduction (SNCR) system which injects urea into the furnace. A CFD simulation of the existing boiler was first conducted and then the furnace was simulated with the SNCR system added and the design was optimised. Operating and capital costs were minimised by optimal placement of 50 injector ports. 6 figs., 2 tabs.

  17. P2VSIM: A SIMULATION AND VISUALIZATION TOOL FOR THE P2V COMPILER

    E-Print Network [OSTI]

    Almeida, Oscar

    2010-07-14T23:59:59.000Z

    P2VSIM: A SIMULATION AND VISUALIZATION TOOL FOR THE P2V COMPILER A Thesis by OSCAR MICHAEL ALMEIDA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE May 2009 Major Subject: Computer Engineering P2VSIM: A SIMULATION AND VISUALIZATION TOOL FOR THE P2V COMPILER A Thesis by OSCAR MICHAEL ALMEIDA Submitted to the Office of Graduate Studies...

  18. A PRODUCTION SIMULATION TOOL FOR SYSTEMS WITH INTEGRATED WIND ENERGY RESOURCES

    E-Print Network [OSTI]

    Gross, George

    A PRODUCTION SIMULATION TOOL FOR SYSTEMS WITH INTEGRATED WIND ENERGY RESOURCES BY NICOLAS BENOIT the energy output of a wind farm in a single location and of those in multiple locations. In this way, we for such planning tools. The incorporation of the wind energy model requires the extension of the widely used

  19. Nonequilibrium candidate Monte Carlo: A new tool for efficient equilibrium simulation

    SciTech Connect (OSTI)

    Nilmeier, Jerome P.; Crooks, Gavin E.; Minh, David D. L.; Chodera, John D.

    2011-11-08T23:59:59.000Z

    Metropolis Monte Carlo simulation is a powerful tool for studying the equilibrium properties of matter. In complex condensed-phase systems, however, it is difficult to design Monte Carlo moves with high acceptance probabilities that also rapidly sample uncorrelated configurations. Here, we introduce a new class of moves based on nonequilibrium dynamics: candidate configurations are generated through a finite-time process in which a system is actively driven out of equilibrium, and accepted with criteria that preserve the equilibrium distribution. The acceptance rule is similar to the Metropolis acceptance probability, but related to the nonequilibrium work rather than the instantaneous energy difference. Our method is applicable to sampling from both a single thermodynamic state or a mixture of thermodynamic states, and allows both coordinates and thermodynamic parameters to be driven in nonequilibrium proposals. While generating finite-time switching trajectories incurs an additional cost, driving some degrees of freedom while allowing others to evolve naturally can lead to large enhancements in acceptance probabilities, greatly reducing structural correlation times. Using nonequilibrium driven processes vastly expands the repertoire of useful Monte Carlo proposals in simulations of dense solvated systems.

  20. Laser shocks: A tool for experimental simulation of damage into materials

    SciTech Connect (OSTI)

    Boustie, M.; Cuq Lelandais, J. P.; Berthe, L.; Ecault, R. [Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France); CEA-DAM Valduc, 21120 Is-sur-Tille (France); Laboratoire Procedes et Ingenierie en Mecanique et Materiaux (CNRS), Arts et Metiers ParisTech, 151 bd de l'Hopital, 75013 PARIS (France); Institut PPRIME, Departement Physique et Mecanique des Materiaux, CNRS-ENSMA-Universite de Poitiers, 1 av Clement Ader, 86961 FUTUROSCOPE Cedex (France)

    2012-07-30T23:59:59.000Z

    High power laser irradiation of solids results in a strong shock wave propagation, driving very high amplitude pressure loadings with very short durations. These particular characteristics offer the possibility to study the behaviour of matter under extreme dynamic conditions in continuity with what is possible with the conventional generators of shock (launchers of projectiles, explosives). An advantage of laser shocks is a possible recovery of the shocked samples presenting the metallurgical effects of the shock in most cases. We introduce the principle of the laser shock generation, the characterization of these shocks, the principal mechanisms and effects associated with their propagation in the solids. We show how laser shocks can be a laboratory tool for simulating shock effects at ultra high strain rate, providing a high in information experimental layout for validation of damage modelling on an extended strain rate range compared to conventional shock generators. New data have been obtained with ultra short femtosecond range irradiation. Experimental data gathered through post mortem observation, time resolved velocity measurement are shown along with numerical associated simulations, showing the possibility to predict the damage behaviour of metallic targets under extreme strain rate up to 10{sup 8} s{sup -1}.

  1. Development of simulation tools for virus shell assembly. Final report

    SciTech Connect (OSTI)

    Berger, Bonnie

    2001-01-05T23:59:59.000Z

    Prof. Berger's major areas of research have been in applying computational and mathematical techniques to problems in biology, and more specifically to problems in protein folding and genomics. Significant progress has been made in the following areas relating to virus shell assembly: development has been progressing on a second-generation self-assembly simulator which provides a more versatile and physically realistic model of assembly; simulations are being developed and applied to a variety of problems in virus assembly; and collaborative efforts have continued with experimental biologists to verify and inspire the local rules theory and the simulator. The group has also worked on applications of the techniques developed here to other self-assembling structures in the material and biological sciences. Some of this work has been conducted in conjunction with Dr. Sorin Istrail when he was at Sandia National Labs.

  2. Kinetic simulations of plasmoid chain dynamics

    SciTech Connect (OSTI)

    Markidis, S. [High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden)] [High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden); Henri, P. [Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d'Azur, Nice (France)] [Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d'Azur, Nice (France); Lapenta, G. [Centrum voor Plasma-Astrofysica, Department Wiskunde, Katholieke Universiteit Leuven, Leuven (Belgium)] [Centrum voor Plasma-Astrofysica, Department Wiskunde, Katholieke Universiteit Leuven, Leuven (Belgium); Divin, A. [Swedish Institute of Space Physics, Uppsala (Sweden)] [Swedish Institute of Space Physics, Uppsala (Sweden); Goldman, M.; Newman, D. [Department of Physics and CIPS, University of Colorado, Boulder 80309-0390 (United States)] [Department of Physics and CIPS, University of Colorado, Boulder 80309-0390 (United States); Laure, E. [PDC and High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden)] [PDC and High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden)

    2013-08-15T23:59:59.000Z

    The dynamics of a plasmoid chain is studied with three dimensional Particle-in-Cell simulations. The evolution of the system with and without a uniform guide field, whose strength is 1/3 the asymptotic magnetic field, is investigated. The plasmoid chain forms by spontaneous magnetic reconnection: the tearing instability rapidly disrupts the initial current sheet generating several small-scale plasmoids that rapidly grow in size coalescing and kinking. The plasmoid kink is mainly driven by the coalescence process. It is found that the presence of guide field strongly influences the evolution of the plasmoid chain. Without a guide field, a main reconnection site dominates and smaller reconnection regions are included in larger ones, leading to an hierarchical structure of the plasmoid-dominated current sheet. On the contrary in presence of a guide field, plasmoids have approximately the same size and the hierarchical structure does not emerge, a strong core magnetic field develops in the center of the plasmoid in the direction of the existing guide field, and bump-on-tail instability, leading to the formation of electron holes, is detected in proximity of the plasmoids.

  3. Annual Report 1999 Environmental Dynamics and Simulation

    SciTech Connect (OSTI)

    NS Foster-Mills

    2000-06-28T23:59:59.000Z

    This annual report describes selected 1999 research accomplishments for the Environmental Dynamics and Simulation (ED and S) directorate, one of six research organizations in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). These accomplishments are representative of the different lines of research underway in the ED and S directorate. EMSL is one of US Department of Energy's (DOE) national scientific user facilities and is the centerpiece of DOE's commitment to providing world-class experimental, theoretical, and computational capabilities for solving the nation's environmental problems. Capabilities in the EMSL include over 100 major instrument systems for use by the resident research staff, their collaborators, and users of the EMSL. These capabilities are used to address the fundamental science that will be the basis for finding solutions to national environmental issues such as cleaning up contamianted areas at DOE sites across the country and developing green technologies that will reduce or eliminate future pollution production. The capabilities are also used to further the understanding of global climate change and environmental issues relevant to energy production and use and health effects resulting from exposure to contaminated environments.

  4. Accelerating atomistic simulations of defect dynamics: Hyperdynamics, parallel replica dynamics, and temperature-accelerated dynamics

    SciTech Connect (OSTI)

    Voter, A.F.; Soerensen, M.R.

    1999-07-01T23:59:59.000Z

    Obtaining a good atomistic description of diffusion dynamics in materials remains a daunting task due to the time-scale limitations of the molecular dynamics method. The authors discuss new methods, derived from transition state theory, for accelerating molecular dynamics simulations of these infrequent-event processes. Two of these methods (hyperdynamics and parallel replica dynamics) have been presented previously, and are briefly reviewed here. The third, temperature-accelerated dynamics (TAD), is presented in detail. In TAD, the system temperature is raised to stimulate more rapid escape out of each potential basin, but attempted transitions are filtered to allow only those that would have occurred at the normal temperature. The characteristics of the methods are compared.

  5. Portable Graphical Tools for Concurrent Plasma Simulation October 18, 1996

    E-Print Network [OSTI]

    Conference Plasma Reactor A Standardized Reactor Design for Research Purposes Experimental Model (left Faculty Sponsor: Dr. Stephen Taylor Abstract Low pressure reactors (less than 1.5 Torr) are used for large­scale simulations of these reactors. In order for Hawk to be convenient for the process engineers

  6. SPINEVOLUTION: A powerful tool for the simulation of solid and liquid state NMR experiments

    E-Print Network [OSTI]

    Griffin, Robert G.

    SPINEVOLUTION: A powerful tool for the simulation of solid and liquid state NMR experiments Mikhail. Simulations of solid-state magic angle spinning (MAS) experiments can be particularly demanding both with complex pulse sequences and multi-spin systems in solids, SPINEVO- LUTION is a versatile and easy to use

  7. A Simulation Tool for Real-time Systems using Environmental Energy Harvesting Maryline CHETTO

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    , the system operates in a so-called energy neutral mode by consuming only as much energy as harvested. The simulator enables to construct an optimal schedule for any task set, battery capacity and energy sourceA Simulation Tool for Real-time Systems using Environmental Energy Harvesting Maryline CHETTO

  8. HYBRID GROUND SOURCE HEAT PUMP SYSTEM SIMULATION USING VISUAL MODELING TOOL FOR HVACSIM+

    E-Print Network [OSTI]

    HYBRID GROUND SOURCE HEAT PUMP SYSTEM SIMULATION USING VISUAL MODELING TOOL FOR HVACSIM+ M.H. Khan, 74078, USA ABSTRACT This paper presents a simulation of a hybrid ground source heat pump system, performed using a new graphical user interface for HVACSIM+. Hybrid ground source heat pump systems

  9. ECMI2008 Abstract Agent-Based Simulation as a Novel Decision Support Tool for Retail Managers

    E-Print Network [OSTI]

    Aickelin, Uwe

    ECMI2008 Abstract Agent-Based Simulation as a Novel Decision Support Tool for Retail Managers Dr Strategy, Learning & Change (LUBS), Leeds, LS2 9JT, UK Abstract: Intelligent agents offer a new and exciting way of understanding the world of work. We apply agent-based simulation to investigate a set

  10. 9/28/98 9:58:58 am, Journal of Non-Crystalline Solids MOLECULAR DYNAMICS SIMULATION OF VITREOUS SILICA STRUCTURES

    E-Print Network [OSTI]

    Goddard III, William A.

    Dynamics (MD) techniques to simulate glass structures has become a valuable tool for gaining insight1 9/28/98 9:58:58 am, Journal of Non-Crystalline Solids MOLECULAR DYNAMICS SIMULATION OF VITREOUS SILICA STRUCTURES Norman T. Huff*, Owens Corning Science and Technology Center, 2790 Columbus Road

  11. DHARMA: A Tool for Evaluating Dynamic Scheduling Algorithms for Realtime Multiprocessor Systems

    E-Print Network [OSTI]

    Manimaran, Govindarasu

    ­tolerance and resource reclaiming. Section 3 reviews the earlier work on dynamic scheduling algorithms. In Section 4, we discuss our dynamic scheduling and reclaiming algorithms. Section 5 discusses the software architectureDHARMA: A Tool for Evaluating Dynamic Scheduling Algorithms for Real­time Multiprocessor Systems G

  12. NREL Evaluates the Thermal Performance of Uninsulated Walls to Improve the Accuracy of Building Energy Simulation Tools (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2012-01-01T23:59:59.000Z

    This technical highlight describes NREL research to develop models of uninsulated wall assemblies that help to improve the accuracy of building energy simulation tools when modeling potential energy savings in older homes. Researchers at the National Renewable Energy Laboratory (NREL) have developed models for evaluating the thermal performance of walls in existing homes that will improve the accuracy of building energy simulation tools when predicting potential energy savings of existing homes. Uninsulated walls are typical in older homes where the wall cavities were not insulated during construction or where the insulating material has settled. Accurate calculation of heat transfer through building enclosures will help determine the benefit of energy efficiency upgrades in order to reduce energy consumption in older American homes. NREL performed detailed computational fluid dynamics (CFD) analysis to quantify the energy loss/gain through the walls and to visualize different airflow regimes within the uninsulated cavities. The effects of ambient outdoor temperature, radiative properties of building materials, and insulation level were investigated. The study showed that multi-dimensional airflows occur in walls with uninsulated cavities and that the thermal resistance is a function of the outdoor temperature - an effect not accounted for in existing building energy simulation tools. The study quantified the difference between CFD prediction and the approach currently used in building energy simulation tools over a wide range of conditions. For example, researchers found that CFD predicted lower heating loads and slightly higher cooling loads. Implementation of CFD results into building energy simulation tools such as DOE2 and EnergyPlus will likely reduce the predicted heating load of homes. Researchers also determined that a small air gap in a partially insulated cavity can lead to a significant reduction in thermal resistance. For instance, a 4-in. tall air gap (Figure 1a) led to a 15% reduction in resistance. Similarly, a 2-ft tall air gap (Figure 1c) led to 54% reduction in thermal resistance. NREL researchers plan to extend this study to include additional wall configurations, and also to evaluate the performance of attic spaces with different insulation levels. NREL's objective is to address each potential issue that leads to inaccuracies in building energy simulation tools to improve the predictions.

  13. Development of a dynamic simulator for a natural gas combined cycle (NGCC) power plant with post-combustion carbon capture

    SciTech Connect (OSTI)

    Liese, E.; Zitney, S.

    2012-01-01T23:59:59.000Z

    The AVESTAR Center located at the U.S. Department of Energy’s National Energy Technology Laboratory and West Virginia University is a world-class research and training environment dedicated to using dynamic process simulation as a tool for advancing the safe, efficient and reliable operation of clean energy plants with CO{sub 2} capture. The AVESTAR Center was launched with a high-fidelity dynamic simulator for an Integrated Gasification Combined Cycle (IGCC) power plant with pre-combustion carbon capture. The IGCC dynamic simulator offers full-scope Operator Training Simulator (OTS) Human Machine Interface (HMI) graphics for realistic, real-time control room operation and is integrated with a 3D virtual Immersive Training Simulator (ITS), thus allowing joint control room and field operator training. The IGCC OTS/ITS solution combines a “gasification with CO{sub 2} capture” process simulator with a “combined cycle” power simulator into a single high-performance dynamic simulation framework. This presentation will describe progress on the development of a natural gas combined cycle (NGCC) dynamic simulator based on the syngas-fired combined cycle portion of AVESTAR’s IGCC dynamic simulator. The 574 MW gross NGCC power plant design consisting of two advanced F-class gas turbines, two heat recovery steam generators (HRSGs), and a steam turbine in a multi-shaft 2x2x1 configuration will be reviewed. Plans for integrating a post-combustion carbon capture system will also be discussed.

  14. Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations

    E-Print Network [OSTI]

    Brenner, Donald W.

    Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations J 2004) An ad hoc thermostating procedure that couples a molecular dynamics (MD) simulation

  15. Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene

    E-Print Network [OSTI]

    Yi, Peng

    Using a realistic united-atom force field, molecular dynamics simulations were performed to study homogeneous nucleation of the crystal phase at about 30% supercooling from the melts of n-pentacontahectane (C150) and a ...

  16. Ab Initio Molecular Dynamics Simulations of Low-Energy Recoil...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    than the ions on lattice sites in perfect MO2. Citation: Xiao HY, Y Zhang, and WJ Weber.2012."Ab Initio Molecular Dynamics Simulations of Low-Energy Recoil Eventsin ThO2,...

  17. Molecular Dynamics Simulation Studies of Electrolytes andElectrolyte...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C. es058smith2010p.pdf More Documents & Publications Molecular dynamics simulation and ab intio...

  18. Ab initio molecular dynamics simulations of low energy recoil...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of low energy recoil events in ceramics . Ab initio molecular dynamics simulations of low energy recoil events in ceramics . Abstract: The recent progress in the use of large-scale...

  19. Molecular simulation as a tool for studying lignin

    SciTech Connect (OSTI)

    Sangha, Amandeep K [ORNL; Petridis, Loukas [ORNL; Smith, Jeremy C [ORNL; Ziebell, Angela L [ORNL; Parks, Jerry M [ORNL

    2012-01-01T23:59:59.000Z

    Lignocellulosic biomass provides a sustainable source of sugars for biofuel and biomaterial production. However, biomass resistance to degradation imposes difficulties for economical conversion of plant carbohydrates to fermentable sugars. One of the key contributors to recalcitrance is lignin. Understanding the properties of lignin macromolecules in the cell wall matrix is useful for manipulating biomass structure to generate more easily degradable biomass. Along with experimental techniques such as 2D-NMR and mass spectrometry, computational techniques can be useful for characterizing the structural and energetic properties of the biomass assembly and its individual constituents. Here, we provide a brief introduction to lignin, review some of the recent, relevant scientific literature, and give our perspectives on the role of molecular simulation in understanding lignin structure.

  20. Field Test Best Practices: A Dynamic Web Tool for Practical Guidance

    Energy Savers [EERE]

    b y t he A lliance f or S ustainable E nergy, L LC. Field Test Best Practices A dynamic web tool for practical guidance BA Webinar Lieko Earle & Bethany Sparn March 18, 2015...

  1. CGILua: A MultiParadigmatic Tool for Creating Dynamic WWW Pages

    E-Print Network [OSTI]

    Ierusalimschy, Roberto

    CGILua: A Multi­Paradigmatic Tool for Creating Dynamic WWW Pages Anna M. Hester Renato Borges'' to mark fields to be filled in. When the page is accessed, the template feeds a pre­processor that creates

  2. Computational Fluid Dynamics Simulation of Fluidized Bed Polymerization Reactors

    SciTech Connect (OSTI)

    Rong Fan

    2006-08-09T23:59:59.000Z

    Fluidized beds (FB) reactors are widely used in the polymerization industry due to their superior heat- and mass-transfer characteristics. Nevertheless, problems associated with local overheating of polymer particles and excessive agglomeration leading to FB reactors defluidization still persist and limit the range of operating temperatures that can be safely achieved in plant-scale reactors. Many people have been worked on the modeling of FB polymerization reactors, and quite a few models are available in the open literature, such as the well-mixed model developed by McAuley, Talbot, and Harris (1994), the constant bubble size model (Choi and Ray, 1985) and the heterogeneous three phase model (Fernandes and Lona, 2002). Most these research works focus on the kinetic aspects, but from industrial viewpoint, the behavior of FB reactors should be modeled by considering the particle and fluid dynamics in the reactor. Computational fluid dynamics (CFD) is a powerful tool for understanding the effect of fluid dynamics on chemical reactor performance. For single-phase flows, CFD models for turbulent reacting flows are now well understood and routinely applied to investigate complex flows with detailed chemistry. For multiphase flows, the state-of-the-art in CFD models is changing rapidly and it is now possible to predict reasonably well the flow characteristics of gas-solid FB reactors with mono-dispersed, non-cohesive solids. This thesis is organized into seven chapters. In Chapter 2, an overview of fluidized bed polymerization reactors is given, and a simplified two-site kinetic mechanism are discussed. Some basic theories used in our work are given in detail in Chapter 3. First, the governing equations and other constitutive equations for the multi-fluid model are summarized, and the kinetic theory for describing the solid stress tensor is discussed. The detailed derivation of DQMOM for the population balance equation is given as the second section. In this section, monovariate population balance, bivariate population balance, aggregation and breakage equation and DQMOM-Multi-Fluid model are described. In the last section of Chapter 3, numerical methods involved in the multi-fluid model and time-splitting method are presented. Chapter 4 is based on a paper about application of DQMOM to polydisperse gas-solid fluidized beds. Results for a constant aggregation and breakage kernel and a kernel developed from kinetic theory are shown. The effect of the aggregation success factor and the fragment distribution function are investigated. Chapter 5 shows the work on validation of mixing and segregation phenomena in gas-solid fluidized beds with a binary mixture or a continuous size distribution. The simulation results are compared with available experiment data and discrete-particle simulation. Chapter 6 presents the project with Univation Technologies on CFD simulation of a Polyethylene pilot-scale FB reactor, The fluid dynamics, mass/heat transfer and particle size distribution are investigated through CFD simulation and validated with available experimental data. The conclusions of this study and future work are discussed in Chapter 7.

  3. N-body simulations in modified Newtonian dynamics

    E-Print Network [OSTI]

    Carlo Nipoti; Pasquale Londrillo; Luca Ciotti

    2008-11-18T23:59:59.000Z

    We describe some results obtained with N-MODY, a code for N-body simulations of collisionless stellar systems in modified Newtonian dynamics (MOND). We found that a few fundamental dynamical processes are profoundly different in MOND and in Newtonian gravity with dark matter. In particular, violent relaxation, phase mixing and galaxy merging take significantly longer in MOND than in Newtonian gravity, while dynamical friction is more effective in a MOND system than in an equivalent Newtonian system with dark matter.

  4. Accelerated molecular dynamics and equation-free methods for simulating diffusion in solids.

    SciTech Connect (OSTI)

    Deng, Jie; Zimmerman, Jonathan A.; Thompson, Aidan Patrick; Brown, William Michael (Oak Ridge National Laboratories, Oak Ridge, TN); Plimpton, Steven James; Zhou, Xiao Wang; Wagner, Gregory John; Erickson, Lindsay Crowl

    2011-09-01T23:59:59.000Z

    Many of the most important and hardest-to-solve problems related to the synthesis, performance, and aging of materials involve diffusion through the material or along surfaces and interfaces. These diffusion processes are driven by motions at the atomic scale, but traditional atomistic simulation methods such as molecular dynamics are limited to very short timescales on the order of the atomic vibration period (less than a picosecond), while macroscale diffusion takes place over timescales many orders of magnitude larger. We have completed an LDRD project with the goal of developing and implementing new simulation tools to overcome this timescale problem. In particular, we have focused on two main classes of methods: accelerated molecular dynamics methods that seek to extend the timescale attainable in atomistic simulations, and so-called 'equation-free' methods that combine a fine scale atomistic description of a system with a slower, coarse scale description in order to project the system forward over long times.

  5. Modeling ramp compression experiments using large-scale molecular dynamics simulation.

    SciTech Connect (OSTI)

    Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)

    2011-10-01T23:59:59.000Z

    Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.

  6. Plasticity of metal wires in torsion: Molecular dynamics and dislocation dynamics simulations

    E-Print Network [OSTI]

    Cai, Wei

    Plasticity of metal wires in torsion: Molecular dynamics and dislocation dynamics simulations t The orientation dependent plasticity in metal nanowires is investigated using molecular dynamics and dislocation wires controls the mechanisms of plastic deformation. For wires oriented along /1 1 0S, dislocations

  7. Plasticity of metallic nanostructures : molecular dynamics simulations 

    E-Print Network [OSTI]

    Healy, Con

    2014-11-27T23:59:59.000Z

    During high speed cutting processes, metals are subject to high strains and strain rates. The dynamic nature of the deformation during high speed cutting makes it difficult to detect atomic scale deformation mechanisms ...

  8. Dynamic Ball & Socket Joint Force Simulator

    E-Print Network [OSTI]

    Farmer, Ryan Neal

    2011-07-26T23:59:59.000Z

    The stability of an implant in the bone, one factor in joint replacement survival, is usually tested using biaxial fatigue loading. These loading protocols do not replicate physiological loading conditions. The Dynamic ...

  9. Reptational dynamics in dissipative particle dynamics simulations of polymer melts

    E-Print Network [OSTI]

    P. Nikunen; I. Vattulainen; M. Karttunen

    2005-12-12T23:59:59.000Z

    Understanding the complex viscoelastic properties of polymeric liquids remains a challenge in materials science and soft matter physics. Here, we present a simple and computationally efficient criterion for the topological constraints in polymeric liquids using the Dissipative Particle Dynamics (DPD). The same approach is also applicable in other soft potential models. For short chains the model correctly reproduces Rouse-like dynamics whereas for longer chains the dynamics becomes reptational as the chain length is increased - something that is not attainable using standard DPD or other coarse-grained soft potential methods. Importantly, no new length scales or forces need to be added.

  10. Research Paper j Using Petri Net Tools to Study Properties and Dynamics of

    E-Print Network [OSTI]

    Rubin, Daniel L.

    Research Paper j Using Petri Net Tools to Study Properties and Dynamics of Biological Systems MOR PELEG, PHD, DANIEL RUBIN, MD, MSC, RUSS B. ALTMAN, MD, PHD A b s t r a c t Petri Nets (PNs concurrent dynamic systems is Petri Nets (PNs).1 An advantage of PNs is that they can represent system

  11. Exceptional tools for studying the structure and dynamics of materials at the molecular level

    E-Print Network [OSTI]

    Exceptional tools for studying the structure and dynamics of materials at the molecular level, complementary to x-rays, in under- standing the structure and dynamics of materials at the molecular level · Soft matter · Magnetism and superconductivity · Life sciences · Structural biology · Complex fluids

  12. Dynamic simulation of a proposed ITER tritium processing system

    SciTech Connect (OSTI)

    Kuan, W.; Abdou, M.A. [Univ. of California, Los Angeles, CA (United States); Scott W.R. [Los Alamos National Lab., NM (United States)

    1995-10-01T23:59:59.000Z

    Dynamically simulating the fuel cycle in a fusion reactor is crucial to developing a better understanding of the safe and reliable operation of this complex system. In this work, we propose a tritium processing system for ITER`s plasma exhaust. The dynamic simulation of this proposed system is then performed with the TRUFFLES (TRitiUm Fusion Fuel cycLE dynamic Simulation) model. The fuel management, storage, and fueling operations are developed and coupled with previous cryopump and fuel cleanup unit subsystems to fully realize the complete torus exhaust flow cycle. Results show that tritium inventories will vary widely depending upon reactor operation, individual subsystem and unit operation designs. A diverse collection of batch-controlled subsystems with changes in their processing parameters are simulated in this work. In particular, the effects from the fuel management subsystem`s fuel reserve and tank switching times are quantified using sensitivity studies. 6 refs., 10 figs., 2 tabs.

  13. Building Design Advisor: Automated integration of multiple simulation tools K. Papamichael, J. LaPorta, H. Chauvet

    E-Print Network [OSTI]

    LBNL-40591 Preprint Building Design Advisor: Automated integration of multiple simulation tools K Design Advisor (BDA) is a software environment that supports the integrated use of multiple analysis

  14. Efficient tools for the simulation of flapping wing flows Jeff D. Eldredge

    E-Print Network [OSTI]

    Eldredge, Jeff

    of novel strategies for lift and propulsion using flapping wings requires the use of computational tools for an artificial boundary treatment. Results of the dynamically shed vorticity and the forces exerted are presented as the explicit introduction of an artificial boundary condition to ensure the correct behavior at infinity

  15. Irish Fisheries Investigations No. 17 F-PRESS: A Stochastic Simulation Tool for

    E-Print Network [OSTI]

    Codling, Edward A.

    to fit in with the ICES conceptual framework for software development. F-PRESS can be used to developIrish Fisheries Investigations No. 17 F-PRESS: A Stochastic Simulation Tool for Developing ........................................................................................................................... 32 Appendix I - Summary of F-PRESS key points

  16. Fluid Simulation as a Tool for Painterly Rendering Sven C. Olsen

    E-Print Network [OSTI]

    Maxwell, Bruce

    Fluid Simulation as a Tool for Painterly Rendering Sven C. Olsen Swarthmore College Bruce A fields in the context of stroke based non- photorealistic rendering allows us to produce stroke behaviors a painterly rendering system very similar to that in [Litwinowicz 1997]. We can create animations based

  17. Projective Dynamics: Fusing Constraint Projections for Fast Simulation Sofien Bouaziz

    E-Print Network [OSTI]

    Plotkin, Joshua B.

    energy potentials that can be solved efficiently using an alternating optimization approach. Inspired Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics--Animation; I.6.8 [Simulation and Modeling of deformable material has become an in- dispensable tool in many areas of computer graphics. Virtual worlds

  18. Massively parallel molecular dynamics simulations of

    E-Print Network [OSTI]

    Berne, Bruce J.

    experimental studies pioneered by Dobson and coworkers have shown that amyloids and fibrils can be formed of their three- dimensional (3D) structure and dynamics at the atomic level. This understanding can not only from the traditional beta-amyloid peptides but also from almost any proteins, such as lysozyme

  19. Programmable quantum simulation by dynamic Hamiltonian engineering

    E-Print Network [OSTI]

    David L. Hayes; Steven T. Flammia; Michael J. Biercuk

    2014-06-18T23:59:59.000Z

    Quantum simulation is a promising near term application for mesoscale quantum information processors, with the potential to solve computationally intractable problems at the scale of just a few dozen interacting quantum systems. Recent experiments in a range of technical platforms have demonstrated the basic functionality of quantum simulation applied to quantum magnetism, quantum phase transitions, and relativistic quantum mechanics. In all cases, the underlying hardware platforms restrict the achievable inter-particle interaction, forming a serious constraint on the ability to realize a versatile, programmable quantum simulator. In this work, we address this problem by developing novel sequences of unitary operations that engineer desired effective Hamiltonians in the time-domain. The result is a hybrid programmable analog simulator permitting a broad class of interacting spin-lattice models to be generated starting only with an arbitrary long-range native inter-particle interaction and single-qubit addressing. Specifically, our approach permits the generation of all symmetrically coupled translation-invariant two-body Hamiltonians with homogeneous on-site terms, a class which includes all spin-1/2 XYZ chains, but generalized to include long-range couplings. Building on previous work proving that universal simulation is possible using both entangling gates and single-qubit unitaries, we show that determining the "program" of unitary pulses to implement an arbitrary spin Hamiltonian can be formulated as a linear program that runs in polynomial time and scales efficiently in hardware resources. Our analysis extends from circuit model quantum information to adiabatic quantum evolutions, where our approach allows for the creation of non-native ground state solutions to a computation.

  20. Modeling and simulation of consumer response to dynamic pricing.

    SciTech Connect (OSTI)

    Valenzuela, J.; Thimmapuram, P.; Kim, J (Decision and Information Sciences); (Auburn Univ.)

    2012-08-01T23:59:59.000Z

    Assessing the impacts of dynamic-pricing under the smart grid concept is becoming extremely important for deciding its full deployment. In this paper, we develop a model that represents the response of consumers to dynamic pricing. In the model, consumers use forecasted day-ahead prices to shift daily energy consumption from hours when the price is expected to be high to hours when the price is expected to be low while maintaining the total energy consumption as unchanged. We integrate the consumer response model into the Electricity Market Complex Adaptive System (EMCAS). EMCAS is an agent-based model that simulates restructured electricity markets. We explore the impacts of dynamic-pricing on price spikes, peak demand, consumer energy bills, power supplier profits, and congestion costs. A simulation of an 11-node test network that includes eight generation companies and five aggregated consumers is performed for a period of 1 month. In addition, we simulate the Korean power system.

  1. Lessons Learned From Dynamic Simulations of Advanced Fuel Cycles

    SciTech Connect (OSTI)

    Steven J. Piet; Brent W. Dixon; Jacob J. Jacobson; Gretchen E. Matthern; David E. Shropshire

    2009-04-01T23:59:59.000Z

    Years of performing dynamic simulations of advanced nuclear fuel cycle options provide insights into how they could work and how one might transition from the current once-through fuel cycle. This paper summarizes those insights from the context of the 2005 objectives and goals of the Advanced Fuel Cycle Initiative (AFCI). Our intent is not to compare options, assess options versus those objectives and goals, nor recommend changes to those objectives and goals. Rather, we organize what we have learned from dynamic simulations in the context of the AFCI objectives for waste management, proliferation resistance, uranium utilization, and economics. Thus, we do not merely describe “lessons learned” from dynamic simulations but attempt to answer the “so what” question by using this context. The analyses have been performed using the Verifiable Fuel Cycle Simulation of Nuclear Fuel Cycle Dynamics (VISION). We observe that the 2005 objectives and goals do not address many of the inherently dynamic discriminators among advanced fuel cycle options and transitions thereof.

  2. Coupled displacive and orderdisorder dynamics in LiNbO3 by molecular-dynamics simulation

    E-Print Network [OSTI]

    Gopalan, Venkatraman

    .1063/1.1669063 Ferroelectric lithium niobate (LiNbO3) has emerged as an important material in surface acoustic wave devices1 the structure and properties of materials. Indeed, atomic-level simulations have been used previously-dynamics MD simulations described here we treat the Coulomb interactions using a direct summation method

  3. DYNAMIC SIMULATION OF INEXTENSIBLE CLOTH Jan Bender, Daniel Bayer and Raphael Diziol

    E-Print Network [OSTI]

    Prautzsch, Hartmut

    DYNAMIC SIMULATION OF INEXTENSIBLE CLOTH Jan Bender, Daniel Bayer and Raphael Diziol Institut für-based modelling, impulse-based simulation, inelastic textiles 1. INTRODUCTION The dynamic simulation of cloth an efficient simulation. For example, Georgii and Westermann (2005) describe a method for a fast dynamic

  4. Simulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine

    E-Print Network [OSTI]

    Rapaport, Dennis C.

    centuries ago and an early competitor of the steam engine, continues to attract interest owing to itsSimulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine D 2009; published 30 April 2009 A nanoscale-sized Stirling engine with an atomistic working fluid has

  5. A Molecular Dynamics Simulation of Hydrogen Storage with SWNTs

    E-Print Network [OSTI]

    Maruyama, Shigeo

    A Molecular Dynamics Simulation of Hydrogen Storage with SWNTs S. Maruyama and T. Kimura, Bunkyo-ku, Tokyo 113-8656, Japan The mechanism of efficient hydrogen storage (1) with SWNTs (2, and the storage amount became about 5 wt % regardless of the tube radius. The number of absorbed hydrogen

  6. Dynamic Simulation of DFIG Wind Turbines on FPGA Boards

    E-Print Network [OSTI]

    Zambreno, Joseph A.

    Dynamic Simulation of DFIG Wind Turbines on FPGA Boards Hao Chen, Student Member, IEEE, Song Sun is a friction coefficient. The wind turbine model is based on the relation between the upstream wind speed V w + 1 where p is the air density; Rw is the wind turbine radius; cp (A, (3) is the performance

  7. Molecular dynamics simulations of boronnitride nanotubes embedded in

    E-Print Network [OSTI]

    Ferrari, Patrik L.

    , theoretical studies suggest that BN nanotubes exhibit an energy gap of about 4--5 eV independent of chiralityMolecular dynamics simulations of boron­nitride nanotubes embedded in amorphous Si­B­N Michael In this article, we examine the elastic properties of boron­nitride nanotubes, which are embedded in amorphous

  8. MOLECULAR DYNAMICS SIMULATION OF THERMAL BOUNDARY CONDUCTANCE BETWEEN SWNT AND

    E-Print Network [OSTI]

    Maruyama, Shigeo

    MOLECULAR DYNAMICS SIMULATION OF THERMAL BOUNDARY CONDUCTANCE BETWEEN SWNT AND SURROUNDING FLUIDS JinHyeok Cha, Shohei Chiashi, Junichiro Shiomi, and Shigeo Maruyama* Department of Mechanical applications. In particular, the thermal boundary conductance (TBC) K between an SWNT and surrounding fluid

  9. adhesive dynamics simulation: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    adhesive dynamics simulation First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 A composite time...

  10. Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation

    E-Print Network [OSTI]

    Brenner, Donald W.

    Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation S.J.V. Frankland *, D hydrogen in individual single-shell carbon nanotubes and nanotube ropes using a semiclassical model. The calculations predict that isolated hydrogen molecules inside of nanotubes have a Raman frequency that increases

  11. Modifying the Soil and Water Assessment Tool to Simulate Cropland Carbon Flux: Model Development and Initial Evaluation

    SciTech Connect (OSTI)

    Zhang, Xuesong; Izaurralde, Roberto C.; Arnold, Jeffrey; Williams, Jimmy R.; Srinivasan, Raghavan

    2013-10-01T23:59:59.000Z

    Climate change is one of the most compelling modern issues and has important implications for almost every aspect of natural and human systems. The Soil and Water Assessment Tool (SWAT) model has been applied worldwide to support sustainable land and water management in a changing climate. However, the inadequacies of the existing carbon algorithm in SWAT limit its application in assessing impacts of human activities on CO2 emission, one important source of greenhouse gases (GHGs) that traps heat in the earth system and results in global warming. In this research, we incorporate a revised version of the CENTURY carbon model into SWAT to describe dynamics of soil organic matter (SOM)- residue and simulate land-atmosphere carbon exchange.

  12. Application of Dynamic Monte Carlo Technique in Proton Beam Radiotherapy using Geant4 Simulation Toolkit

    E-Print Network [OSTI]

    Guan, Fada 1982-

    2012-04-27T23:59:59.000Z

    Monte Carlo method has been successfully applied in simulating the particles transport problems. Most of the Monte Carlo simulation tools are static and they can only be used to perform the static simulations for the problems with fixed physics...

  13. SPEE: A Secure Program Execution Environment Tool Using Static and Dynamic Code Verification

    E-Print Network [OSTI]

    Simha, Rahul

    SPEE: A Secure Program Execution Environment Tool Using Static and Dynamic Code Verification Olga those using the Internet and exploiting the vul- nerabilities in the software and applications, software ­ for software integrity protection and authentication and presents performance results. Our system architecture

  14. UNH Jerard/Fussell 1 Project Summary -Dynamic Evaluation of Machine Tool Process Capability

    E-Print Network [OSTI]

    New Hampshire, University of

    UNH ­ Jerard/Fussell 1 Project Summary - Dynamic Evaluation of Machine Tool Process Capability large and small plant operations and decisions. For example, we show some real world examples where part, annual expenditures on machining operations total more than $200 Billion or about 2% of GDP. · Self

  15. Generic solar photovoltaic system dynamic simulation model specification.

    SciTech Connect (OSTI)

    Ellis, Abraham; Behnke, Michael Robert; Elliott, Ryan Thomas

    2013-10-01T23:59:59.000Z

    This document is intended to serve as a specification for generic solar photovoltaic (PV) system positive-sequence dynamic models to be implemented by software developers and approved by the WECC MVWG for use in bulk system dynamic simulations in accordance with NERC MOD standards. Two specific dynamic models are included in the scope of this document. The first, a Central Station PV System model, is intended to capture the most important dynamic characteristics of large scale (> 10 MW) PV systems with a central Point of Interconnection (POI) at the transmission level. The second, a Distributed PV System model, is intended to represent an aggregation of smaller, distribution-connected systems that comprise a portion of a composite load that might be modeled at a transmission load bus.

  16. Simulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine

    E-Print Network [OSTI]

    Rapaport, D C

    2009-01-01T23:59:59.000Z

    A nanoscale-sized Stirling engine with an atomistic working fluid has been modeled using molecular dynamics simulation. The design includes heat exchangers based on thermostats, pistons attached to a flywheel under load, and a regenerator. Key aspects of the behavior, including the time-dependent flows, are described. The model is shown to be capable of stable operation while producing net work at a moderate level of efficiency.

  17. Transient Solid Dynamics Simulations on the Sandia/Intel Teraflop Computer

    E-Print Network [OSTI]

    Hendrickson, Bruce

    and structure of PRONTO. In Section 3 we explain why transient dynamics simulations have been difficultTransient Solid Dynamics Simulations on the Sandia/Intel Teraflop Computer Stephen Attaway \\Lambda Plimpton \\Lambda and Courtenay Vaughan \\Lambda Abstract Transient solid dynamics simulations are among

  18. Molecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single crystals

    E-Print Network [OSTI]

    Southern California, University of

    Molecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single Abstract The oxidation of aluminum single crystals is studied using molecular dynamics (MD) simulations with dynamic charge transfer between atoms. The simulations are performed on three aluminum low-index surfaces

  19. MODELING PLANT COMPETITION WITH THE GAPS OBJECT-ORIENTED DYNAMIC SIMULATION MODEL

    E-Print Network [OSTI]

    Rossiter, D G "David"

    MODELING PLANT COMPETITION WITH THE GAPS OBJECT-ORIENTED DYNAMIC SIMULATION MODEL David G. Rossiter of Agronomy, Inc. #12;MODELING PLANT COMPETITION WITH THE GAPS OBJECT-ORIENTED DYNAMIC SIMULATION MODEL Abstract Modeling inter-species competition is a natural application for dynamic simulation models

  20. Large-Scale Molecular Dynamics Simulations for Highly Parallel Infrastructures

    E-Print Network [OSTI]

    Pazúriková, Jana

    2014-01-01T23:59:59.000Z

    Computational chemistry allows researchers to experiment in sillico: by running a computer simulations of a biological or chemical processes of interest. Molecular dynamics with molecular mechanics model of interactions simulates N-body problem of atoms$-$it computes movements of atoms according to Newtonian physics and empirical descriptions of atomic electrostatic interactions. These simulations require high performance computing resources, as evaluations within each step are computationally demanding and billions of steps are needed to reach interesting timescales. Current methods decompose the spatial domain of the problem and calculate on parallel/distributed infrastructures. Even the methods with the highest strong scaling hit the limit at half a million cores: they are not able to cut the time to result if provided with more processors. At the dawn of exascale computing with massively parallel computational resources, we want to increase the level of parallelism by incorporating parallel-in-time comput...

  1. New Structural-Dynamics Module for Offshore Multimember Substructures within the Wind Turbine Computer-Aided Engineering Tool FAST: Preprint

    SciTech Connect (OSTI)

    Song, H.; Damiani, R.; Robertson, A.; Jonkman, J.

    2013-08-01T23:59:59.000Z

    FAST, developed by the National Renewable Energy Laboratory (NREL), is a computer-aided engineering (CAE) tool for aero-hydro-servo-elastic analysis of land-based and offshore wind turbines. This paper discusses recent upgrades made to FAST to enable loads simulations of offshore wind turbines with fixed-bottom, multimember support structures (e.g., jackets and tripods, which are commonly used in transitional-depth waters). The main theory and strategies for the implementation of the multimember substructure dynamics module (SubDyn) within the new FAST modularization framework are introduced. SubDyn relies on two main engineering schematizations: 1) a linear frame finite-element beam (LFEB) model and 2) a dynamics system reduction via Craig-Bampton's method. A jacket support structure and an offshore system consisting of a turbine atop a jacket substructure were simulated to test the SubDyn module and to preliminarily assess results against results from a commercial finite-element code.

  2. E-Print Network 3.0 - alliances simulation platform Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and analysis tool capable of analyzing floating platform concepts for offshore wind turbines. The new modeling... dynamic simulation tool will enable the development of...

  3. Molecular Dynamics Simulations from SNL's Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Plimpton, Steve; Thompson, Aidan; Crozier, Paul

    LAMMPS (http://lammps.sandia.gov/index.html) stands for Large-scale Atomic/Molecular Massively Parallel Simulator and is a code that can be used to model atoms or, as the LAMMPS website says, as a parallel particle simulator at the atomic, meso, or continuum scale. This Sandia-based website provides a long list of animations from large simulations. These were created using different visualization packages to read LAMMPS output, and each one provides the name of the PI and a brief description of the work done or visualization package used. See also the static images produced from simulations at http://lammps.sandia.gov/pictures.html The foundation paper for LAMMPS is: S. Plimpton, Fast Parallel Algorithms for Short-Range Molecular Dynamics, J Comp Phys, 117, 1-19 (1995), but the website also lists other papers describing contributions to LAMMPS over the years.

  4. Structure and dynamics of nonaqueous mixtures of dipolar liquids. II. Molecular dynamics simulations

    E-Print Network [OSTI]

    2000 Molecular dynamics simulations have been used to study mixtures of acetone/methanol, acetonitrile/ methanol, and acetone/acetonitrile over their entire composition range. Using the effective pair potentials in these two papers is on the nonaqueous dipolar liquid mixtures of acetone/methanol, acetonitrile

  5. An Introduction to MolecularAn Introduction to Molecular Dynamics SimulationsDynamics Simulations

    E-Print Network [OSTI]

    Mura, Cameron

    details · Strengths & weaknesses · Force fields · Available software; pros & cons; how to do a simulation) from Talkington, Siuzdak, Williamson, Nature v438 (2005) CameronMura;May2007 #12;Background) systems: noble gas elements, etc. theoretical and organic chemistry fields; 196070s theoretical

  6. Dynamic Simulation and Optimization of Nuclear Hydrogen Production Systems

    SciTech Connect (OSTI)

    Paul I. Barton; Mujid S. Kaximi; Georgios Bollas; Patricio Ramirez Munoz

    2009-07-31T23:59:59.000Z

    This project is part of a research effort to design a hydrogen plant and its interface with a nuclear reactor. This project developed a dynamic modeling, simulation and optimization environment for nuclear hydrogen production systems. A hybrid discrete/continuous model captures both the continuous dynamics of the nuclear plant, the hydrogen plant, and their interface, along with discrete events such as major upsets. This hybrid model makes us of accurate thermodynamic sub-models for the description of phase and reaction equilibria in the thermochemical reactor. Use of the detailed thermodynamic models will allow researchers to examine the process in detail and have confidence in the accurary of the property package they use.

  7. Accurate direct Eulerian simulation of dynamic elastic-plastic flow

    SciTech Connect (OSTI)

    Kamm, James R [Los Alamos National Laboratory; Walter, John W [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    The simulation of dynamic, large strain deformation is an important, difficult, and unsolved computational challenge. Existing Eulerian schemes for dynamic material response are plagued by unresolved issues. We present a new scheme for the first-order system of elasto-plasticity equations in the Eulerian frame. This system has an intrinsic constraint on the inverse deformation gradient. Standard Godunov schemes do not satisfy this constraint. The method of Flux Distributions (FD) was devised to discretely enforce such constraints for numerical schemes with cell-centered variables. We describe a Flux Distribution approach that enforces the inverse deformation gradient constraint. As this approach is new and novel, we do not yet have numerical results to validate our claims. This paper is the first installment of our program to develop this new method.

  8. Learning environment simulator: a tool for local decision makers and first responders

    SciTech Connect (OSTI)

    Leclaire, Rene J [Los Alamos National Laboratory; Hirsch, Gary B [CLE, INCORPORATED

    2009-01-01T23:59:59.000Z

    The National Infrastructure Simulation and Analysis Center (NISAC) has developed a prototype learning environment simulator (LES) based on the Critical Infrastructure Protection Decision Support System (CIPDSS) infrastructure and scenario models. The LES is designed to engage decision makers at the grass-roots level (local/city/state) to deepen their understanding of an evolving crisis, enhance their intuition and allow them to test their own strategies for events before they occur. An initial version is being developed, centered on a pandemic influenza outbreak and has been successfully tested with a group of hospital administrators and first responders. LES is not a predictive tool but rather a simulated environment allowing the user to experience the complexities of a crisis before it happens. Users can contrast various approaches to the crisis, competing with alternative strategies of their own or other participants. LES is designed to assist decision makers in making informed choices by functionally representing relevant scenarios before they occur, including impacts to critical infrastructures with their interdependencies, and estimating human health & safety and economic impacts. In this paper a brief overview of the underlying models are given followed by a description of the LES, its interface and usage and an overview of the experience testing LES with a group of hospital administrators and first responders. The paper concludes with a brief discussion of the work remaining to make LES operational.

  9. Reservoir Modeling by Data Integration via Intermediate Spaces and Artificial Intelligence Tools in MPS Simulation Frameworks

    SciTech Connect (OSTI)

    Ahmadi, Rouhollah, E-mail: rouhollahahmadi@yahoo.com [Amirkabir University of Technology, PhD Student at Reservoir Engineering, Department of Petroleum Engineering (Iran, Islamic Republic of)] [Amirkabir University of Technology, PhD Student at Reservoir Engineering, Department of Petroleum Engineering (Iran, Islamic Republic of); Khamehchi, Ehsan [Amirkabir University of Technology, Faculty of Petroleum Engineering (Iran, Islamic Republic of)] [Amirkabir University of Technology, Faculty of Petroleum Engineering (Iran, Islamic Republic of)

    2013-12-15T23:59:59.000Z

    Conditioning stochastic simulations are very important in many geostatistical applications that call for the introduction of nonlinear and multiple-point data in reservoir modeling. Here, a new methodology is proposed for the incorporation of different data types into multiple-point statistics (MPS) simulation frameworks. Unlike the previous techniques that call for an approximate forward model (filter) for integration of secondary data into geologically constructed models, the proposed approach develops an intermediate space where all the primary and secondary data are easily mapped onto. Definition of the intermediate space, as may be achieved via application of artificial intelligence tools like neural networks and fuzzy inference systems, eliminates the need for using filters as in previous techniques. The applicability of the proposed approach in conditioning MPS simulations to static and geologic data is verified by modeling a real example of discrete fracture networks using conventional well-log data. The training patterns are well reproduced in the realizations, while the model is also consistent with the map of secondary data.

  10. Molecular Dynamics Simulations of Solutions at Constant Chemical Potential

    E-Print Network [OSTI]

    Perego, Claudio; Parrinello, Michele

    2015-01-01T23:59:59.000Z

    Molecular Dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, that range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, that influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a Grand-Canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work we propose the C$\\mu$MD method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the C$\\mu$MD method to the paradigmatic case of urea crystall...

  11. Molecular Dynamics Simulation of Collisions between Hydrogen and Graphite

    E-Print Network [OSTI]

    A. Ito; H. Nakamura

    2006-04-26T23:59:59.000Z

    Hydrogen adsorption by graphite is examined by classical molecular dynamics simulation using a modified Brenner REBO potential. Such interactions are typical in chemical sputtering experiments, and knowledge of the fundamental behavior of hydrogen and graphene in collisional conditions is essential for modeling the sputtering mechanism. The hydrogen adsorption rate is found to be dependent on the incident hydrogen energy and not on graphene temperature. Rather than destroying the graphene, hydrogen incidence at energies of less than 100 eV can be classified into three regimes of adsorption, reflection and penetration through one or more graphene layers. Incidence at the lowest energies is shown to distort the graphene structure.

  12. With faster processors and better numerical techniques, computational fluid dynamics (CFD) tools have revolutionized engineering design and optimization--

    E-Print Network [OSTI]

    Chapman, Clark R.

    With faster processors and better numerical techniques, computational fluid dynamics (CFD) tools have revolutionized engineering design and optimization-- limiting expensive experimentation and Engineering Division (GED) at Southwest Research Institute® (SwRI®) has extensive experience and capabilities

  13. Spatially resolved dynamic structure factor of finite systems from molecular dynamics simulations

    SciTech Connect (OSTI)

    Raitza, Thomas; Roepke, Gerd; Reinholz, Heidi; Morozov, Igor [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Institut fuer Theoretische Physik, Johannes-Kepler-Universitaet Linz, A-4040 Linz, Austria and Institute of Physics, University of Western Australia, Perth, WA 6009 (Australia); Joint Institute for High Temperatures of RAS, 13 Izhorskaya Street, Building 2, Moscow RU-125412 (Russian Federation)

    2011-09-15T23:59:59.000Z

    The dynamical response of metallic clusters up to 10{sup 3} atoms is investigated using the restricted molecular dynamics simulations scheme. Exemplarily, a sodium like material is considered. Correlation functions are evaluated to investigate the spatial structure of collective electron excitations and the optical response of laser-excited clusters. In particular, the spectrum of bilocal correlation functions shows resonances representing different modes of collective excitations inside the nano plasma. The spatial structure, the resonance energy, and the width of the eigenmodes have been investigated for various values of electron density, temperature, cluster size, and ionization degree. Comparison with bulk properties is performed and the dispersion relation of collective excitations is discussed.

  14. Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes Shigeo MARUYAMA1,2

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes * Shigeo-8656 The hydrogen storage mechanism of SWNTs was studied through molecular dynamics simulations. Assuming the simple : Molecular Dynamics Method, Hydrogen Storage, Single Walled Carbon Nanotubes, Lennard-Jones, Adsorption

  15. Semiclassical molecular dynamics simulations of excited state double-proton transfer in 7-azaindole dimers

    E-Print Network [OSTI]

    Miller, William H.

    Semiclassical molecular dynamics simulations of excited state double-proton transfer in 7-azaindole chemical re- action. In this paper we report the first application of molecular dynamics simulation methods to model the excited state double-proton transfer dynamics involved in the tau- tomerization reaction

  16. Modeling dilute sediment suspension using large-eddy simulation with a dynamic mixed model

    E-Print Network [OSTI]

    Fringer, Oliver B.

    Modeling dilute sediment suspension using large-eddy simulation with a dynamic mixed model Yi Transport of suspended sediment in high Reynolds number channel flows Re=O 600 000 is simulated using large-eddy simulation along with a dynamic-mixed model DMM . Because the modeled sediment concentration is low

  17. HyPro: A Financial Tool for Simulating Hydrogen Infrastructure Development, Final Report

    SciTech Connect (OSTI)

    Brian D. James, Peter O. Schmidt, Julie Perez

    2008-12-01T23:59:59.000Z

    This report summarizes a multi-year Directed Technologies Inc. (DTI) project to study the build-out of hydrogen production facilities during the transition from gasoline internal combustion engine vehicle to hydrogen fuel cell vehicles. The primary objectives of the project are to develop an enhanced understanding of hydrogen production issues during the transition period (out to 2050) and to develop recommendations for the DOE on areas of further study. These objectives are achieved by conducting economic and scenario analysis to predict how industry would provide the hydrogen production, delivery and dispensing capabilities necessary to satisfy increased hydrogen demand. The primary tool used for the analysis is a custom created MatLab simulation tool entitled HyPro (short for Hydrogen Production). This report describes the calculation methodology used in HyPro, the baseline assumptions, the results of the baseline analysis and several corollary studies. The appendices of this report included a complete listing of model assumptions (capital costs, efficiencies, feedstock prices, delivery distances, etc.) and a step-by-step manual on the specific operation of the HyPro program. This study was made possible with funding from the U.S. Department of Energy (DOE).

  18. Equilibration of experimentally determined protein structures for molecular dynamics simulation Emily B. Walton and Krystyn J. VanVliet*

    E-Print Network [OSTI]

    Van Vliet, Krystyn J.

    Equilibration of experimentally determined protein structures for molecular dynamics simulation well studied, ranging from refinements of static x-ray crystallog- raphy structures to dynamic Preceding molecular dynamics simulations of biomolecular interactions, the molecule of interest is often

  19. Physics and Algorithm Enhancements for a Validated MCNP/X Monte Carlo Simulation Tool, Phase VII

    SciTech Connect (OSTI)

    McKinney, Gregg W [Los Alamos National Laboratory

    2012-07-17T23:59:59.000Z

    Currently the US lacks an end-to-end (i.e., source-to-detector) radiation transport simulation code with predictive capability for the broad range of DHS nuclear material detection applications. For example, gaps in the physics, along with inadequate analysis algorithms, make it difficult for Monte Carlo simulations to provide a comprehensive evaluation, design, and optimization of proposed interrogation systems. With the development and implementation of several key physics and algorithm enhancements, along with needed improvements in evaluated data and benchmark measurements, the MCNP/X Monte Carlo codes will provide designers, operators, and systems analysts with a validated tool for developing state-of-the-art active and passive detection systems. This project is currently in its seventh year (Phase VII). This presentation will review thirty enhancements that have been implemented in MCNPX over the last 3 years and were included in the 2011 release of version 2.7.0. These improvements include 12 physics enhancements, 4 source enhancements, 8 tally enhancements, and 6 other enhancements. Examples and results will be provided for each of these features. The presentation will also discuss the eight enhancements that will be migrated into MCNP6 over the upcoming year.

  20. Design and Evaluation of SOCR Tools for Simulation in Undergraduate Probability and Statistics Courses

    E-Print Network [OSTI]

    Christou, Nicolas; Dinov, Ivo D; Sanchez, Juana

    2007-01-01T23:59:59.000Z

    simulation based applets can enhance students’ learning,of simulations in relation to the students’ learning styles.use simulations only for one or the other learning style

  1. Atomistic simulation of structure and dynamics of columnar phases of hexabenzocoronene derivatives

    E-Print Network [OSTI]

    Denis Andrienko; Valentina Marcon; Kurt Kremer

    2006-07-27T23:59:59.000Z

    Using atomistic molecular dynamics simulations we study solid and liquid crystalline columnar discotic phases formed by alkyl-substituted hexabenzocoronene mesogens. Correlations between the molecular structure, packing, and dynamical properties of these materials are established.

  2. The Effect of Model Parameters on the Simulation of Fire Dynamics 

    E-Print Network [OSTI]

    Jahn, Wolfram; Rein, Guillermo; Torero, Jose L

    2008-01-01T23:59:59.000Z

    The sensitivity of computer fire modelling using results from NIST’s Fire Dynamics Simulator (FDS) to a set of input parameters related to fire growth has been analyzed. The scenario simulated is the real-scale Dalmarnock ...

  3. Evaluation of servo, geometric and dynamic error sources on five axis high-speed machine tool

    E-Print Network [OSTI]

    Andolfatto, Loïc; Mayer, René

    2011-01-01T23:59:59.000Z

    Many sources of errors exist in the manufacturing process of complex shapes. Some approximations occur at each step from the design geometry to the machined part. The aim of the paper is to present a method to evaluate the effect of high speed and high dynamic load on volumetric errors at the tool center point. The interpolator output signals and the machine encoder signals are recorded and compared to evaluate the contouring errors resulting from each axis follow-up error. The machine encoder signals are also compared to the actual tool center point position as recorded with a non-contact measuring instrument called CapBall to evaluate the total geometric errors. The novelty of the work lies in the method that is proposed to decompose the geometric errors in two categories: the quasi-static geometric errors independent from the speed of the trajectory and the dynamic geometric errors, dependent on the programmed feed rate and resulting from the machine structure deflection during the acceleration of its axes...

  4. Development of an object-oriented dynamics simulator for a LFR DEMO

    SciTech Connect (OSTI)

    Ponciroli, R.; Bortot, S.; Lorenzi, S.; Cammi, A. [Politecnico di Milano, Dept. of Energy, CeSNEF-Nuclear Engineering Div., via Ponzio 34/3, 20133 Milano (Italy)

    2012-07-01T23:59:59.000Z

    A control-oriented dynamics simulator for a Generation IV Lead-cooled Fast Reactor (LFR) demonstrator (DEMO) has been developed aimed at providing a flexible, simple and fast-running tool allowing to perform design-basis transient and stability analyses, and to lay the foundations for the study of the system control strategy. For such purposes, a model representing a compromise between accuracy and straightforwardness has been necessarily sought, and in this view an object-oriented approach based on the Modelica language has been adopted. The reactor primary and secondary systems have been implemented by assembling both component models already available in a specific thermal-hydraulic library, and ad hoc developed nuclear component models suitably modified according to the specific DEMO configuration. The resulting overall plant simulator, incorporating also the balance of plant, consists in the following essential parts: core, integrated steam generator/primary pump block, cold and hot legs, primary coolant cold pool, turbine, heat sink, secondary coolant pump. Afterwards, the reactor response to typical transient initiators has been investigated: feedwater mass flow rate and temperature enhancement, turbine admission valve coefficient variation, increase of primary coolant mass flow rate, and transient of overpower have been simulated; results have been compared with the outcomes of analogous analyses performed by employing a lumped-parameter DEMO plant model. (authors)

  5. Experimental simulation of charge conservation violation and Majorana dynamics

    E-Print Network [OSTI]

    R. Keil; C. Noh; A. Rai; S. Stützer; S. Nolte; D. G. Angelakis; A. Szameit

    2014-04-22T23:59:59.000Z

    Unphysical particles are commonly ruled out from the solution of physical equations, as they fundamentally cannot exist in any real system and, hence, cannot be examined experimentally in a direct fashion. One of the most celebrated equations that allows unphysical solutions is the relativistic Majorana equation\\cite{Majorana} which might describe neutrinos and other exotic particles beyond the Standard Model. The equation's physical solutions, the Majorana fermions, are predicted to be their own anti-particles and as a consequence they have to be neutrally charged; the charged version however (called Majoranon) is, due to charge non-conservation, unphysical and cannot exist. On the other hand, charge conservation violation has been contemplated in alternative theories associated with higher spacetime dimensions or a non-vanishing photon mass; theories whose exotic nature makes experimental testing with current technology an impossible task. In our work, we present an experimental scheme based on optics with which we simulate the dynamics of a Majoranon, involving the implementation of unphysical charge conjugation and complex conjugation. We show that the internal dynamics of the Majoranon is fundamentally different from that of its close cousin, the Dirac particle, to illustrate the nature of the unphysical operations. For this we exploit the fact that in quantum mechanics the wave function itself is not a measurable quantity. Therefore, wave functions of real physical particles, in our case Dirac particles with opposite masses, can be superposed to a wave function of an unphysical particle, the Majoranon. Our results open a new front in the field of quantum simulations of exotic phenomena, with possible applications in condensed matter physics, topological quantum computing, and testing theories within and beyond the Standard Model with existing technology.

  6. Localized dynamic subgrid closure for simulation of magnetohydrodynamic turbulence

    SciTech Connect (OSTI)

    Miki, Kenji; Menon, Suresh [Georgia Institute of Technology, School of Aerospace Engineering, Atlanta, Georgia 30332-0150 (United States)

    2008-07-15T23:59:59.000Z

    A local dynamic kinetic energy model (LDKM) for large-eddy simulation (LES) of magnetohydrodynamic (MHD) turbulence is proposed. The proposed MHD turbulence model evaluates all model coefficients locally and dynamically without any ad hoc averaging. This model also does not assume low magnetic Reynolds numbers. The turbulent residual-helicity effect ({alpha}-effect) appearing in the magnetic induction equation is successfully modeled. For validation, high-Re decaying isotropic decay turbulence with and without a mean magnetic field are studied using LES. The effect of rotation is also studied. For the case without rotation, it is observed that the energy spectrum follows a k{sup -5/3} law. For the case with rotation, it is shown that two mechanisms, phase scrambling due to frame rotation and Joule dissipation, are competing, and two distinct regimes with respect to rotation rate are observed. There is a critical rotation rate at which the energy decays most in MHD turbulence. It is also shown that this MHD-LDKM model is applicable to wide variety of high/low magnetic Reynolds number applications.

  7. RECENT PROGRESS IN DYNAMIC PROCESS SIMULATION OF CRYOGENIC REFRIGERATORS

    SciTech Connect (OSTI)

    Kuendig, A. [Linde Kryotechnik AG, Dattlikonerstrasse 5, CH-8422 Pfungen (Switzerland)

    2008-03-16T23:59:59.000Z

    At the CEC 2005 a paper with the title 'Helium refrigerator design for pulsed heat load in Tokamaks' was presented. That paper highlighted the control requirements for cryogenic refrigerators to cope with the expected load variations of future nuclear fusion reactors. First dynamic computer simulations have been presented.In the mean time, the computer program is enhanced and a new series of process simulations are available. The new program considers not only the heat flows and the temperature variations within the heat exchangers, but also the variation of mass flows and pressure drops. The heat transfer numbers now are calculated in dependence of the flow speed and the gas properties. PI-controllers calculate the necessary position of specific valves for maintaining pressures, temperatures and the rotation speed of turbines.Still unsatisfactory is the fact, that changes in the process arrangement usually are attended by adjustments in the program code. It is the main objective of the next step of development a more flexible code which enables that any user defined process arrangements can be assembled by input data.

  8. Molecular Dynamics Simulation of Thermodynamic Properties in Uranium Dioxide

    SciTech Connect (OSTI)

    Wang, Xiangyu; Wu, Bin; Gao, Fei; Li, Xin; Sun, Xin; Khaleel, Mohammad A.; Akinlalu, Ademola V.; Liu, L.

    2014-03-01T23:59:59.000Z

    In the present study, we investigated the thermodynamic properties of uranium dioxide (UO2) by molecular dynamics (MD) simulations. As for solid UO2, the lattice parameter, density, and enthalpy obtained by MD simulations were in good agreement with existing experimental data and previous theoretical predictions. The calculated thermal conductivities matched the experiment results at the midtemperature range but were underestimated at very low and very high temperatures. The calculation results of mean square displacement represented the stability of uranium at all temperatures and the high mobility of oxygen toward 3000 K. By fitting the diffusivity constant of oxygen with the Vogel-Fulcher-Tamman law, we noticed a secondary phase transition near 2006.4 K, which can be identified as a ‘‘strong’’ to ‘‘fragile’’ supercooled liquid or glass phase transition in UO2. By fitting the oxygen diffusion constant with the Arrhenius equation, activation energies of 2.0 and 2.7 eV that we obtained were fairly close to the recommended values of 2.3 to 2.6 eV. Xiangyu Wang, Bin Wu, Fei Gao, Xin Li, Xin Sun, Mohammed A. Khaleel, Ademola V. Akinlalu and Li Liu

  9. Photoionization analysis of chemo-dynamical dwarf galaxies simulations

    E-Print Network [OSTI]

    Melekh, B; Hensler, G; Buhajenko, O

    2015-01-01T23:59:59.000Z

    Photoionization modelling allows to follow the transport, the emergence, and the absorption of photons taking into account all important processes in nebular plasmas. Such modelling needs the spatial distribution of density, chemical abundances and temperature, that can be provided by chemo-dynamical simulations (ChDS) of dwarf galaxies. We perform multicomponent photoionization modelling (MPhM) of the ionized gas using 2-D ChDSs of dwarf galaxies. We calculate emissivity maps for important nebular emission lines. Their intensities are used to derive the chemical abundance of oxygen by the so-called Te- and R23-methods. Some disagreements are found between oxygen abundances calculated with these methods and the ones coming from the ChDSs. We investigate the fraction of ionizing radiation emitted in the star-forming region which is able to leak out the galaxy. The time- and direction-averaged escape fraction in our simulation is 0.35-0.4. Finally, we have calculated the total Halpha lumi- nosity of our model g...

  10. Molecular dynamics simulation studies of structural and dynamical properties of rapidly quenched Al

    SciTech Connect (OSTI)

    Shen, B. [Fudan University; Liu, C. Y. [Zhengzhou University; Jia, Y. [Zhengzhou University; Yue, G. Q. [Fudan University; Ke, F. S. [Fudan University; Zhao, H. B. [Fudan University; Chen, L. Y. [Fudan University; Wang, S. Y. [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Ho, Kai-Ming [Ames Laboratory

    2013-06-11T23:59:59.000Z

    The structural and dynamical properties of rapidly quenched Al are studied by molecular dynamics simulations. The pair-correlation function of high temperature liquid Al agrees well with the experimental results. Different cooling rates are applied with high cooling rates leading to glass formation, while low cooling rates leading to crystallization. The local structures are characterized by Honeycutt–Andersen indices and Voronoi tessellation analysis. The results show that for high cooling rates, the local structures of the liquid and glassy Al are predominated by icosahedral clusters, together with considerable amount of face-centered cubic and hexagonal close packed short-range orders. These short-range order results are further confirmed using the recently developed atomic cluster alignment method. Moreover, the atomic cluster alignment clearly shows the crystal nucleation process in supercooled liquid of Al. Finally, the mean square displacement for the liquid is also analyzed, and the corresponding diffusion coefficient as a function of temperature is calculated.

  11. A Molecular Dynamics Simulation of Hydrogen Storage by SWNTs Tatsuto Kimuraa

    E-Print Network [OSTI]

    Maruyama, Shigeo

    A Molecular Dynamics Simulation of Hydrogen Storage by SWNTs Tatsuto Kimuraa and Shigeo Maruyamab of efficient hydrogen storage [1] with SWNTs [2,3] was studied through classical molecular dynamics simulations adsorbed hydrogen molecules was almost proportional to the number of carbon atoms, and the storage amount

  12. Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Molecular Dynamics Simulation of Hydrogen Storage with Single Walled Carbon Nanotubes Shigeo MARUYAMA #12;The hydrogen storage mechanism of SWNTs was studied through molecular dynamics simulations,12) Fig. 6 Hydrogen storage inside each SWNT #12;Table 1 Potential parameters between SWNTs Tube d0 [Ã?

  13. A Numerical Model for the Dynamic Simulation of a Recirculation Single-Effect Absorption Chiller

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    A Numerical Model for the Dynamic Simulation of a Recirculation Single- Effect Absorption Chiller A dynamic model for the simulation of a new single-effect water/lithium bromide absorption chiller is developed. The chiller is driven by two distinct heat sources, includes a custom integrated falling film

  14. Molecular Dynamics Simulations of Laser Induced Incandescence Dr. Adri van Duin

    E-Print Network [OSTI]

    Bjørnstad, Ottar Nordal

    Molecular Dynamics Simulations of Laser Induced Incandescence (LII) Dr. Adri van Duin Associate of Engineering. Laser Induced Incandescence (LII) is a popular method to estimate the properties of soot. Molecular Dynamics Simulations of Laser-Induced Incandescence of Soot Using an Extended ReaxFF Reactive

  15. Molecular dynamics simulations of the elastic properties of polymer/carbon nanotube composites

    E-Print Network [OSTI]

    Elliott, James

    Molecular dynamics simulations of the elastic properties of polymer/carbon nanotube composites Yue composite. However, improvements in properties are by no means guaranteed, and the results are often in the composite. In this paper, we present classical molecular dynamics (MD) simulations of model polymer

  16. Molecular Dynamics Simulation of Nucleation of SWNT from a Metal Particle on a Substrate

    E-Print Network [OSTI]

    Maruyama, Shigeo

    a transition metal cluster on a substrate is studied using classical molecular dynamics (MD) simulations between pure metal and metal-carbide. Graphite structure gradually precipitates from the edgeMolecular Dynamics Simulation of Nucleation of SWNT from a Metal Particle on a Substrate Yasushi

  17. Coupling of a multizone airflow simulation program with computational fluid dynamics for indoor environmental analysis

    E-Print Network [OSTI]

    Gao, Yang, 1974-

    2002-01-01T23:59:59.000Z

    Current design of building indoor environment comprises macroscopIC approaches, such as CONT AM multizone airflow analysis tool, and microscopic approaches that apply Computational Fluid Dynamics (CFD). Each has certain ...

  18. An Energy-Aware Simulation Model and Transaction Protocol for Dynamic Workload Distribution in Mobile Ad Hoc Networks1

    E-Print Network [OSTI]

    Pedram, Massoud

    An Energy-Aware Simulation Model and Transaction Protocol for Dynamic Workload Distribution California {tari, prong, pedram}@usc.edu Abstract This paper introduces a network simulation model

  19. Verifiable Fuel Cycle Simulation Model (VISION): A Tool for Analyzing Nuclear Fuel Cycle Futures

    SciTech Connect (OSTI)

    Jacob J. Jacobson; Steven J. Piet; Gretchen E. Matthern; David E. Shropshire; Robert F. Jeffers; A. M. Yacout; Tyler Schweitzer

    2010-11-01T23:59:59.000Z

    The nuclear fuel cycle consists of a set of complex components that are intended to work together. To support the nuclear renaissance, it is necessary to understand the impacts of changes and timing of events in any part of the fuel cycle system such as how the system would respond to each technological change, a series of which moves the fuel cycle from where it is to a postulated future state. The system analysis working group of the United States research program on advanced fuel cycles (formerly called the Advanced Fuel Cycle Initiative) is developing a dynamic simulation model, VISION, to capture the relationships, timing, and changes in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model components and some examples of how to use VISION. For example, VISION users can now change yearly the selection of separation or reactor technologies, the performance characteristics of those technologies, and/or the routing of material among separation and reactor types - with the model still operating on a PC in <5 min.

  20. Note: Local thermal conductivities from boundary driven non-equilibrium molecular dynamics simulations

    SciTech Connect (OSTI)

    Bresme, F., E-mail: f.bresme@imperial.ac.uk [Department of Chemistry, Chemical Physics Section, Imperial College London, London SW7 2AZ (United Kingdom); Department of Chemistry, Norwegian University of Science and Technology, Trondheim (Norway); Armstrong, J., E-mail: j.armstrong@imperial.ac.uk [Department of Chemistry, Chemical Physics Section, Imperial College London, London SW7 2AZ (United Kingdom)

    2014-01-07T23:59:59.000Z

    We report non-equilibrium molecular dynamics simulations of heat transport in models of molecular fluids. We show that the “local” thermal conductivities obtained from non-equilibrium molecular dynamics simulations agree within numerical accuracy with equilibrium Green-Kubo computations. Our results support the local equilibrium hypothesis for transport properties. We show how to use the local dependence of the thermal gradients to quantify the thermal conductivity of molecular fluids for a wide range of thermodynamic states using a single simulation.

  1. Dynamic simulation of dual-speed wind turbine generation

    SciTech Connect (OSTI)

    Muljadi, E.; Butterfield, C.P.

    1996-10-01T23:59:59.000Z

    Induction generators have been used since the early development of utility-scale wind turbine generation. An induction generator is the generator of choice because of its ruggedness, and low cost. With an induction generator, the operating speed of the wind turbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using two induction generators with two different rated speeds. With single- speed operation, the wind turbine operates at different power coefficients (Cp) as the wind speed varies. The operation at maximum Cp can occur only at a single wind speed. However, if the wind speed varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the wind turbine to operate at near maximum Cp over a wider range of wind-speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative to capture more energy than single-speed operation. In this paper, dual-speed operation of a wind turbine will be investigated. One type of control algorithm for dual- speed operation is proposed. Results from a dynamic simulation will be presented to show how the control algorithm works and how power, current and torque of the system vary as the wind turbine is exposed to varying wind speeds.

  2. Semiclassical Molecular Dynamics Simulations of the Excited State Photodissociation Dynamics of H2O in the A1B1 Band

    E-Print Network [OSTI]

    Wu, Yinghua

    Semiclassical Molecular Dynamics Simulations of the Excited State Photodissociation Dynamics of H2O modeled in terms of classical molecular dynamics simulations.9,12 However, the photodissociation from The photodissociation dynamics of H2O in the A1 B1 band is investigated by implementing a recently developed time

  3. Diffusive Dynamics of Water inside Hydrophobic Carbon Micropores Studied by Neutron Spectroscopy and Molecular Dynamics Simulation

    E-Print Network [OSTI]

    S. O. Diallo; L. Vlcek; E. Mamontov; J. K. Keum; Jihua Chen; J. S. Hayes Jr.; A. A. Chialvo

    2014-12-15T23:59:59.000Z

    When water molecules are confined to nanoscale spacings, such as in the nanometer size pores of activated carbon fiber (ACF), their freezing point gets suppressed down to very low temperatures ($\\sim$ 150 K), leading to a metastable liquid state with remarkable physical properties. We have investigated the ambient pressure diffusive dynamics of water in microporous Kynol\\texttrademark ACF-10 (average pore size $\\sim$11.6 {\\AA}, with primarily slit-like pores) from temperature $T=$ 280 K in its stable liquid state down to $T=$ 230 K into the metastable supercooled phase. The observed characteristic relaxation times and diffusion coefficients are found to be respectively higher and lower than those in bulk water, indicating a slowing down of the water mobility with decreasing temperature. The observed temperature-dependent average relaxation time $$ when compared to previous findings indicate that it is the size of the confining pores - not their shape - that primarily affects the dynamics of water for pore sizes larger than 10 {\\AA}. The experimental observations are compared to complementary molecular dynamics simulations of a model system, in which we studied the diffusion of water within the 11.6 {\\AA} gap of two parallel graphene sheets. We find generally a reasonable agreement between the observed and calculated relaxation times at the low momentum transfer $Q$ ($Q\\le 0.9$ \\AA${^{-1}}$). At high $Q$ however, where localized dynamics becomes relevant, this ideal system does not satisfactorily reproduce the measurements. The best agreement is obtained for the diffusion parameter $D$ associated with the hydrogen-site when a representative stretched exponential function, rather than the standard bi-modal exponential model, is used to parameterize the self-correlation function $I(Q,t)$.

  4. On the modeling and simulation of reaction-transfer dynamics in semiconductor-electrolyte solar cells

    E-Print Network [OSTI]

    Ren, Kui

    -performance semiconductor-liquid junction solar cells. We propose in this work a macroscopic mathematical model, a sys- tem-liquid junction, solar cell simulation, naso-scale device modeling. 1 Introduction The mathematical modeling by the increasing need of simulation tools for designing efficient solar cells to harvest sunlight for clean energy

  5. Development of Design and Simulation Tool for Hybrid Geothermal Heat Pump System

    Broader source: Energy.gov [DOE]

    This project will expand Expand eQUEST, a building energy analysis software with latest implementation of DOE-2, for simulations of HGSHP systems and improve its existing simulation capabilities for ordinary GSHP systems.

  6. Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Horizontal Window Frames with Internal Cavities

    SciTech Connect (OSTI)

    Gustavsen, Arlid; Kohler, Christian; Dalehaug, Arvid; Arasteh, Dariush

    2008-12-01T23:59:59.000Z

    This paper assesses the accuracy of the simplified frame cavity conduction/convection and radiation models presented in ISO 15099 and used in software for rating and labeling window products. Temperatures and U-factors for typical horizontal window frames with internal cavities are compared; results from Computational Fluid Dynamics (CFD) simulations with detailed radiation modeling are used as a reference. Four different frames were studied. Two were made of polyvinyl chloride (PVC) and two of aluminum. For each frame, six different simulations were performed, two with a CFD code and four with a building-component thermal-simulation tool using the Finite Element Method (FEM). This FEM tool addresses convection using correlations from ISO 15099; it addressed radiation with either correlations from ISO 15099 or with a detailed, view-factor-based radiation model. Calculations were performed using the CFD code with and without fluid flow in the window frame cavities; the calculations without fluid flow were performed to verify that the CFD code and the building-component thermal-simulation tool produced consistent results. With the FEM-code, the practice of subdividing small frame cavities was examined, in some cases not subdividing, in some cases subdividing cavities with interconnections smaller than five millimeters (mm) (ISO 15099) and in some cases subdividing cavities with interconnections smaller than seven mm (a breakpoint that has been suggested in other studies). For the various frames, the calculated U-factors were found to be quite comparable (the maximum difference between the reference CFD simulation and the other simulations was found to be 13.2 percent). A maximum difference of 8.5 percent was found between the CFD simulation and the FEM simulation using ISO 15099 procedures. The ISO 15099 correlation works best for frames with high U-factors. For more efficient frames, the relative differences among various simulations are larger. Temperature was also compared, at selected locations on the frames. Small differences was found in the results from model to model. Finally, the effectiveness of the ISO cavity radiation algorithms was examined by comparing results from these algorithms to detailed radiation calculations (from both programs). Our results suggest that improvements in cavity heat transfer calculations can be obtained by using detailed radiation modeling (i.e. view-factor or ray-tracing models), and that incorporation of these strategies may be more important for improving the accuracy of results than the use of CFD modeling for horizontal cavities.

  7. Quantify Water Extraction by TBP/Dodecane via Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    Khomami, Bamin [Univ. of Tennessee, Knoxville, TN (United States); Cui, Shengting [Univ. of Tennessee, Knoxville, TN (United States); de Almeida, Valmor F. [Oak Ridge National Lab., Oak Ridge, TN (United States); Felker, Kevin [Oak Ridge National Lab., Oak Ridge, TN (United States)

    2013-05-16T23:59:59.000Z

    The purpose of this project is to quantify the interfacial transport of water into the most prevalent nuclear reprocessing solvent extractant mixture, namely tri-butyl- phosphate (TBP) and dodecane, via massively parallel molecular dynamics simulations on the most powerful machines available for open research. Specifically, we will accomplish this objective by evolving the water/TBP/dodecane system up to 1 ms elapsed time, and validate the simulation results by direct comparison with experimentally measured water solubility in the organic phase. The significance of this effort is to demonstrate for the first time that the combination of emerging simulation tools and state-of-the-art supercomputers can provide quantitative information on par to experimental measurements for solvent extraction systems of relevance to the nuclear fuel cycle. Results: Initially, the isolated single component, and single phase systems were studied followed by the two-phase, multicomponent counterpart. Specifically, the systems we studied were: pure TBP; pure n-dodecane; TBP/n-dodecane mixture; and the complete extraction system: water-TBP/n-dodecane two phase system to gain deep insight into the water extraction process. We have completely achieved our goal of simulating the molecular extraction of water molecules into the TBP/n-dodecane mixture up to the saturation point, and obtained favorable comparison with experimental data. Many insights into fundamental molecular level processes and physics were obtained from the process. Most importantly, we found that the dipole moment of the extracting agent is crucially important in affecting the interface roughness and the extraction rate of water molecules into the organic phase. In addition, we have identified shortcomings in the existing OPLS-AA force field potential for long-chain alkanes. The significance of this force field is that it is supposed to be optimized for molecular liquid simulations. We found that it failed for dodecane and/or longer chains for this particular solvent extraction application. We have proposed a simple way to circumvent the artificial crystallization of the chains at ambient temperature.

  8. Finite Element Modelling and Molecular Dynamic Simulations of Carbon nanotubes/ Polymer Composites

    E-Print Network [OSTI]

    Gaddamanugu, Dhatri

    2010-07-14T23:59:59.000Z

    Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading...

  9. Parallel Simulation of Subsonic Fluid Dynamics on a Cluster of Workstations

    E-Print Network [OSTI]

    Skordos, Panayotis A.

    1995-12-01T23:59:59.000Z

    An effective approach of simulating fluid dynamics on a cluster of non- dedicated workstations is presented. The approach uses local interaction algorithms, small communication capacity, and automatic migration of parallel ...

  10. Molecular Dynamics Simulation of the Transport Properties of Molten Transuranic Chloride Salts

    E-Print Network [OSTI]

    Baty, Austin Alan

    2013-02-06T23:59:59.000Z

    are critical to modeling both the neutronics and heat transfer of an ADSMS system. There is a lack of experimental data on the density, heat capacity, electrical and thermal conductivities, and viscosity of TRUCl3 salt systems. Molecular dynamics simulations...

  11. Nonequilibrium molecular dynamics simulations of confined fluids in contact with the bulk

    E-Print Network [OSTI]

    Zhang, Luzheng

    Nonequilibrium molecular dynamics simulations of confined fluids in contact with the bulk Luzheng Zhang, Ramkumar Balasundaram,a) and Stevin H. Gehrke Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506 Shaoyi Jiangb) Department of Chemical Engineering, University

  12. Building Dynamic Models of Service Compositions with Simulation of Provision Resources

    E-Print Network [OSTI]

    Dustdar, Schahram

    Building Dynamic Models of Service Compositions with Simulation of Provision Resources Dragan compositions depends both on the composition structure, and on planning and management of compu- tational resources necessary for provision. Resource constraints on the service provider side have impact

  13. Instructor authoring tool : a step towards promoting dynamic lecture-style classrooms

    E-Print Network [OSTI]

    Chen, Jessie I

    2006-01-01T23:59:59.000Z

    The Instructor Authoring Tool of the Classroom Learning Partner project provides an efficient tool for university professors and other teachers of lecture-style classrooms to construct lecture slides that can easily ...

  14. Self-similar multiscale structure of lignin revealed by neutron scattering and molecular dynamics simulation

    SciTech Connect (OSTI)

    Petridis, Loukas [ORNL; Pingali, Sai Venkatesh [ORNL; Urban, Volker S [ORNL; Heller, William T [ORNL; O'Neill, Hugh Michael [ORNL; Foston, Marcus [Georgia Institute of Technology; Ragauskas, A J [Georgia Institute of Technology; Smith, Jeremy C [ORNL

    2011-01-01T23:59:59.000Z

    Lignin, a major polymeric component of plant cell walls, forms aggregates in vivo and poses a barrier to cellulosic ethanol production. Here, neutron scattering experiments and molecular dynamics simulations reveal that lignin aggregates are characterized by a surface fractal dimension that is invariant under change of scale from ~1 1000 . The simulations also reveal extensive water penetration of the aggregates and heterogeneous chain dynamics corresponding to a rigid core with a fluid surface.

  15. Experimental characterization of energetic material dynamics for multiphase blast simulation.

    SciTech Connect (OSTI)

    Beresh, Steven Jay; Wagner, Justin L.; Kearney, Sean Patrick; Wright, Elton K.; Baer, Melvin R.; Pruett, Brian Owen Matthew

    2011-09-01T23:59:59.000Z

    Currently there is a substantial lack of data for interactions of shock waves with particle fields having volume fractions residing between the dilute and granular regimes, which creates one of the largest sources of uncertainty in the simulation of energetic material detonation. To close this gap, a novel Multiphase Shock Tube has been constructed to drive a planar shock wave into a dense gas-solid field of particles. A nearly spatially isotropic field of particles is generated in the test section by a gravity-fed method that results in a spanwise curtain of spherical 100-micron particles having a volume fraction of about 19%. Interactions with incident shock Mach numbers of 1.66, 1.92, and 2.02 were achieved. High-speed schlieren imaging simultaneous with high-frequency wall pressure measurements are used to reveal the complex wave structure associated with the interaction. Following incident shock impingement, transmitted and reflected shocks are observed, which lead to differences in particle drag across the streamwise dimension of the curtain. Shortly thereafter, the particle field begins to propagate downstream and spread. For all three Mach numbers tested, the energy and momentum fluxes in the induced flow far downstream are reduced about 30-40% by the presence of the particle field. X-Ray diagnostics have been developed to penetrate the opacity of the flow, revealing the concentrations throughout the particle field as it expands and spreads downstream with time. Furthermore, an X-Ray particle tracking velocimetry diagnostic has been demonstrated to be feasible for this flow, which can be used to follow the trajectory of tracer particles seeded into the curtain. Additional experiments on single spherical particles accelerated behind an incident shock wave have shown that elevated particle drag coefficients can be attributed to increased compressibility rather than flow unsteadiness, clarifying confusing results from the historical database of shock tube experiments. The development of the Multiphase Shock Tube and associated diagnostic capabilities offers experimental capability to a previously inaccessible regime, which can provide unprecedented data concerning particle dynamics of dense gas-solid flows.

  16. Hybrid Electro-Mechanical Simulation Tool for Wind Turbine Generators: Preprint

    SciTech Connect (OSTI)

    Singh, M.; Muljadi, E.; Jonkman, J.

    2013-05-01T23:59:59.000Z

    This paper describes the use of MATLAB/Simulink to simulate the electrical and grid-related aspects of a WTG and the FAST aero-elastic wind turbine code to simulate the aerodynamic and mechanical aspects of the WTG. The combination of the two enables studies involving both electrical and mechanical aspects of the WTG.

  17. Simulation of Borehole Resistivity Tools Through Metal Casing at Different Frequencies Using a Goal

    E-Print Network [OSTI]

    Torres-Verdín, Carlos

    the efficiency and accuracy of the method, allowing for high-accuracy simulations of logging instruments-FEM that accurately simulates these logging instruments. This approach is needed to design and predict the behavior, Manuscript received January 20, 2005. This work was supported by the oil-company Baker-Atlas. we provide

  18. Molecular dynamics simulation of Li surface erosion and bubble formation

    E-Print Network [OSTI]

    Harilal, S. S.

    .49.Sf Keywords: Liquid metal; Lithium; Ion-surface interactions 1. Introduction Bombardment Structure and dynamical properties of liquid Li containing He atoms were studied by the Molecular Dynamics characteristics of light low-energy ions on a liquid Li surface and their diffusion properties have attracted much

  19. AB INITIO MOLECULAR-DYNAMICS SIMULATIONS OF DYE MOLECULES ON SURFACES

    E-Print Network [OSTI]

    Entel, P.

    AB INITIO MOLECULAR-DYNAMICS SIMULATIONS OF DYE MOLECULES ON SURFACES M. SUGIHARA1 , H. MEYER2 , P, Austria We have performed ab initio total energy calculations and molecular-dynamics sim- ulations of dye molecules on NaCl(100) surfaces and in water. The flat dye molecule trimethine, [C19H17N2O2]+, which forms

  20. Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense Helium

    E-Print Network [OSTI]

    Militzer, Burkhard

    Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense integral Monte Carlo (PIMC) and density func- tional molecular dynamics (DFT-MD), are applied to study hot excitation mecha- nisms that determine their behavior at high temperature. The helium atom has two ionization

  1. CFD Simulation of Dynamic Thrust and Radial Forces on a Vertical Axis Wind Turbine Blade

    E-Print Network [OSTI]

    Tullis, Stephen

    CFD Simulation of Dynamic Thrust and Radial Forces on a Vertical Axis Wind Turbine Blade K. Mc vibration source of a small scale vertical axis wind turbine. The dynamic loading on the blades of the turbine, as they rotate about the central shaft and travel through a range of relative angles of attack

  2. Hybrid approach for including electronic and nuclear quantum effects in molecular dynamics simulations of hydrogen transfer

    E-Print Network [OSTI]

    Hammes-Schiffer, Sharon

    Hybrid approach for including electronic and nuclear quantum effects in molecular dynamics January 2001 A hybrid approach for simulating proton and hydride transfer reactions in enzymes coefficient and to investigate the real-time dynamics of reactive trajectories. This hybrid approach includes

  3. On the self-similarity assumption in dynamic models for large eddy simulations

    E-Print Network [OSTI]

    Van Den Eijnden, Eric

    that the present formulation of the DP is usually incompatible with its under- lying self-similarity assumption SSAOn the self-similarity assumption in dynamic models for large eddy simulations Daniele Carati eddy simulations and their underlying self-similarity assumption is discussed. The interpretation

  4. A Simulation Approach to Dynamic Portfolio Choice with an Application to Learning

    E-Print Network [OSTI]

    Stroud, Jonathan

    A Simulation Approach to Dynamic Portfolio Choice with an Application to Learning About Return 2000 This Draft: December 2003 Abstract We present a simulation-based method for solving discrete, parameter and model uncertainty, and learning. We first establish the properties of the method

  5. FORCulator: a micromagnetic tool for simulating first-order reversal curve diagrams

    E-Print Network [OSTI]

    Harrison, Richard J.

    2014-12-05T23:59:59.000Z

    parameters [Dunlop, 2002a, 2002b] can often lead to an ambiguous or misleading assessment of a rock’s magnetic mineralogy. FORC diagrams, on the other hand, offer the possibility of unambiguous domain-state fingerprinting, extraction of domain... to geometry-specific signatures in FORC diagrams that inform our understanding of the underlying magnetic mineralogy. 2. FORC Simulation Approaches: Pros and Cons Several methods for simulating FORC diagrams have been successfully employed in the past. Here we...

  6. SIMULATING MARKET TRANSFORMATION DYNAMICS USING A HYBRID ENERGY ECONOMY MODEL

    E-Print Network [OSTI]

    AT THE ADOPTION OF HYDROGEN FUEL CELL VEHICLES by Jimena Eyzaguirre M.Sc. Geology, University of Western Ontario, to develop policy-relevant information about dynamics in consumer preferences for hydrogen fuel cell vehicles

  7. PARALLEL DYNAMICMESH LAGRANGIAN METHOD FOR SIMULATION FLOWS WITH DYNAMIC INTERFACES

    E-Print Network [OSTI]

    Antaki, James F.

    the aerospace, automotive, biomedical, chemical, marine, materials, wind engineering sciences. These include, material description motion results in dynamic meshes, become hopelessly distorted unless regularly large­amplitude vibrations such flexible aerodynamic components high aspect wings blades; mixtures

  8. Molecular dynamics simulation of phosphorylation-induced conformational transitions in the mycobacterium tuberculosis response regulator PrrA

    SciTech Connect (OSTI)

    Chen, Guo [Los Alamos National Laboratory; Mcmahon, Benjamin H [Los Alamos National Laboratory; Tung, Chang - Shung [Los Alamos National Laboratory

    2008-01-01T23:59:59.000Z

    Phosphorylation-activated modulation of response regulators (RR) is predominantly used by bacteria as a strategy in regulating their two-component signaling (TCS) systems, the underlying molecular mechanisms are however far from fully understood. In this work we have conducted a molecular dynamics (MD) simulation of the phosphorylation-induced conformational transitions of RRs with the Mycobacterium Tuberculosis PrrA as a particular example. Starting from the full-length inactive structure of PrrA we introduced a local disturbance by phosphorylating the conserved aspartic acid residue, Asp-58, in the regulatory domain. A Go-model-type algorithm packaged with AMBER force fields was then applied to simulate the dynamics upon phosphorylation. The MD simulation shows that the phosphorylation of Asp-58 facilitates PrrA, whose inactive state has a compact conformation with a closed interdomain interface, to open up with its interdomain separation being increased by an average of about 1.5 {angstrom} for a simulation of 20 ns. The trans-activation loop, which is completely buried within the interdomain interface in the inactive PrrA, is found to become more exposed with the phosphorylated structure as well. These results provide more structural details of how the phosphorylation of a local aspartate activates PrrA to undergo a global conformational rearrangement toward its extended active state. This work also indicates that MD simulations can serve as a fast tool to unravel the regulation mechanisms of all RRs, which is especially valuable when the structures of full-length active RRs are currently unavailable.

  9. A Quasi-Dynamic HVAC and Building Simulation Methodology

    E-Print Network [OSTI]

    Davis, Clinton Paul

    2012-07-16T23:59:59.000Z

    to their design and simulated in a computationally efficient manner. The methodology represents a system as interconnected, object-oriented sub-models known as components. Fluids and their local properties are modeled using discrete, incompressible objects known...

  10. Multiplatform Dynamic System Simulation of a DC-DC Converter.

    E-Print Network [OSTI]

    Song, Wenpeng

    2012-01-01T23:59:59.000Z

    ??The work presented in this paper focuses on the usability testing for the Open-Modelica. The modeling and simulation of the BMR450 DC-DC converter is also… (more)

  11. Fluidic Catalytic Cracking Power Recovery Dynamic Computer Simulation

    E-Print Network [OSTI]

    Samurin, N. A.

    1980-01-01T23:59:59.000Z

    Fluidic Cat Crackers (FCC) using the catalyst regeneration cycle are candidates for more power efficient operation by the use of high temperature dirty gas expanders. In a previous paper, a computer simulation was described for the steady state...

  12. Molecular Dynamics Simulations of Heat Transfer In Nanoscale Liquid Films

    E-Print Network [OSTI]

    Kim, Bo Hung

    2010-07-14T23:59:59.000Z

    is almost a constant for ??f /? parabolic temperature profiles in the domain with temperature jumps due to the Kapitza resistance at the liquid/solid interfaces. Using the energy dissipation rates predicted by MD simulations...

  13. Design and Simulation for Architectural Geometry Figure 1: Daytime and nighttime scenes of designed roof by using the developed computational tools

    E-Print Network [OSTI]

    roof by using the developed computational tools 031.PDF Keywords: Architectural Geometry, Procedural an innovative computational design tool used to edit architectural geometry interactively and demonstratesDesign and Simulation for Architectural Geometry Figure 1: Daytime and nighttime scenes of designed

  14. Extended Lagrangian quantum molecular dynamics simulations of shock-induced chemistry in hydrocarbons

    SciTech Connect (OSTI)

    Sanville, Edward J [Los Alamos National Laboratory; Bock, Nicolas [Los Alamos National Laboratory; Challacombe, William M [Los Alamos National Laboratory; Cawkwell, Marc J [Los Alamos National Laboratory; Niklasson, Anders M N [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Stephen [Los Alamos National Laboratory; Sewell, Thomas D [UNIV OF MISSOURI

    2010-01-01T23:59:59.000Z

    A set of interatomic potentials for hydrocarbons that are based upon the self-consistent charge transfer tight-binding approximation to density functional theory have been developed and implemented into the quantum molecular dynamics code ''LATTE''. The interatomic potentials exhibit an outstanding level of transferability and have been applied in molecular dynamics simulations of tert-butylacetylene under thermodynamic conditions that correspond to its single-shock Hugoniot. We have achieved precise conservation of the total energy during microcanonical molecular dynamics trajectories under incomplete convergence via the extended Lagrangian Born-Oppenheimer molecular dynamics formalism. In good agreement with the results of a series of flyer-plate impact experiments, our SCC-TB molecular dynamics simulations show that tert-butylactylene molecules polymerize at shock pressures around 6.1 GPa.

  15. Dynamic Human Reliability Analysis: Benefits and Challenges of Simulating Human Performance

    SciTech Connect (OSTI)

    R. L. Boring

    2007-06-01T23:59:59.000Z

    To date, there has been considerable work on dynamic event trees and other areas related to dynamic probabilistic safety assessment (PSA). The counterpart to these efforts in human reliability analysis (HRA) has centered on the development of specific methods to account for the dynamic nature of human performance. In this paper, the author posits that the key to dynamic HRA is not in the development of specific methods but in the utilization of cognitive modeling and simulation to produce a framework of data that may be used in quantifying the likelihood of human error. This paper provides an overview of simulation approaches to HRA; reviews differences between first, second, and dynamic generation HRA; and outlines potential benefits and challenges of this approach.

  16. An investigation of soil-tool interaction theories as they apply to a Lunar soil simulant

    E-Print Network [OSTI]

    Willman, Brian Michael

    1992-01-01T23:59:59.000Z

    developed for finding the force required to fail soil with a blade, given the appropriate parameters of the blade, the soil, and their interaction. The properties of interest in the Lunar soil are presented in this thesis. Then the parameters of a... terrestrial analog of the true Lunar soil is determined. Given these, the predictive models are implemented to predict the required force to fail the Lunar soil simulant with a flat blade. An apparatus is developed to fail the prepared Lunar soil simulant...

  17. A dynamic process model of a natural gas combined cycle -- Model development with startup and shutdown simulations

    SciTech Connect (OSTI)

    Liese, Eric [U.S. DOE; Zitney, Stephen E. [U.S. DOE

    2013-01-01T23:59:59.000Z

    Research in dynamic process simulation for integrated gasification combined cycles (IGCC) with carbon capture has been ongoing at the National Energy Technology Laboratory (NETL), culminating in a full operator training simulator (OTS) and immersive training simulator (ITS) for use in both operator training and research. A derivative work of the IGCC dynamic simulator has been a modification of the combined cycle section to more closely represent a typical natural gas fired combined cycle (NGCC). This paper describes the NGCC dynamic process model and highlights some of the simulator’s current capabilities through a particular startup and shutdown scenario.

  18. A Micro-Grid Simulator Tool (SGridSim) using Effective Node-to-Node Complex Impedance (EN2NCI) Models

    SciTech Connect (OSTI)

    Udhay Ravishankar; Milos manic

    2013-08-01T23:59:59.000Z

    This paper presents a micro-grid simulator tool useful for implementing and testing multi-agent controllers (SGridSim). As a common engineering practice it is important to have a tool that simplifies the modeling of the salient features of a desired system. In electric micro-grids, these salient features are the voltage and power distributions within the micro-grid. Current simplified electric power grid simulator tools such as PowerWorld, PowerSim, Gridlab, etc, model only the power distribution features of a desired micro-grid. Other power grid simulators such as Simulink, Modelica, etc, use detailed modeling to accommodate the voltage distribution features. This paper presents a SGridSim micro-grid simulator tool that simplifies the modeling of both the voltage and power distribution features in a desired micro-grid. The SGridSim tool accomplishes this simplified modeling by using Effective Node-to-Node Complex Impedance (EN2NCI) models of components that typically make-up a micro-grid. The term EN2NCI models means that the impedance based components of a micro-grid are modeled as single impedances tied between their respective voltage nodes on the micro-grid. Hence the benefit of the presented SGridSim tool are 1) simulation of a micro-grid is performed strictly in the complex-domain; 2) faster simulation of a micro-grid by avoiding the simulation of detailed transients. An example micro-grid model was built using the SGridSim tool and tested to simulate both the voltage and power distribution features with a total absolute relative error of less than 6%.

  19. Ion and Electron Dynamics in Nonlinear PIC Simulations

    SciTech Connect (OSTI)

    Jolliet, S.; Angelino, P.; Tran, T. M.; McMillan, B. F.; Sauter, O.; Villard, L. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland); Bottino, A.; Peeters, A. G.; Poli, E. [Max Planck Institut fuer Plasmaphysik, IPP-EURATOM Association, Garching (Germany); Hatzky, R. [Computer Center of the Max-Planck-Gesellschaft, D 85748 Garching (Germany)

    2006-11-30T23:59:59.000Z

    ITG and ETG turbulence is investigated with the nonlinear global PIC code ORB5. The large variety of numerical schemes and simulations domains used has sometimes lead to important discrepancies in the transport predictions. In order to discuss these disagreements, emphasis must be put on ways to check the numerical accuracy, such as energy conservation and numerical noise measurement. This paper therefore presents benchmarks, new algorithms and a noise diagnostic. After having demonstrated the numerical quality of our simulations, 2 topics are visited: the unclear role of the parallel nonlinearity and the transport level in ETG turbulence, for which predictions differing by one order of magnitude had been made elsewhere.

  20. From Balanced Initial Occupant Distribution to Balanced Exit Usage in a Simulation Model of Pedestrian Dynamics

    E-Print Network [OSTI]

    Kretz, Tobias

    2012-01-01T23:59:59.000Z

    It is tested in this contribution if and to which extend a method of a pedestrian simulation tool that attempts to make pedestrians walk into the direction of estimated earliest arrival can help to automatically distribute pedestrians - who are initially distributed arbitrarily in the scenario - equally on the various exits of the scenario.

  1. Integrated Dynamic Simulation for Process Optimization and Control

    E-Print Network [OSTI]

    Rubloff, Gary W.

    wherever possible ­ Radiative heat transfer ­ Mass balance ­ Boundary layer transport ­ Surface adsorption;Schematics of Polysilicon RT-CVD Reactor MFC gas cylinder heating lamps RTP reactor RTP pumps 1st stage 2nd-level description ­ Reduced-order models to represent high complexity (e.g., reactor fluid dynamics, heat transfer

  2. Darlington tritium removal facility and station upgrading plant dynamic process simulation

    SciTech Connect (OSTI)

    Busigin, A. [NITEK USA, Inc., 6405 NW 77 PL, Parkland, FL 33067 (United States); Williams, G. I. D.; Wong, T. C. W.; Kulczynski, D.; Reid, A. [Ontario Power Generation Nuclear, Box 4000, Bowmanville, ON L1C 3Z8 (Canada)

    2008-07-15T23:59:59.000Z

    Ontario Power Generation Nuclear (OPGN) has a 4 x 880 MWe CANDU nuclear station at its Darlington Nuclear Div. located in Bowmanville. The station has been operating a Tritium Removal Facility (TRF) and a D{sub 2}O station Upgrading Plant (SUP) since 1989. Both facilities were designed with a Distributed Control System (DCS) and programmable logic controllers (PLC) for process control. This control system was replaced with a DCS only, in 1998. A dynamic plant simulator was developed for the Darlington TRF (DTRF) and the SUP, as part of the computer control system replacement. The simulator was used to test the new software, required to eliminate the PLCs. The simulator is now used for operator training and testing of process control software changes prior to field installation. Dynamic simulation will be essential for the ITER isotope separation system, where the process is more dynamic than the relatively steady-state DTRF process. This paper describes the development and application of the DTRF and SUP dynamic simulator, its benefits, architecture, and the operational experience with the simulator. (authors)

  3. Molecular Dynamics Simulations to Study Protein Folding and Unfolding

    E-Print Network [OSTI]

    Caflisch, Amedeo

    and results are essential in validating the force fields (V7 10/11 13:29) VCH/G J-1079 Buchner I PMU: WSL data is conditio sine qua non to validate the simulation results and very helpful for improv- ing force

  4. EnergyGauge USA: A Residential Building Energy Simulation Design Tool

    E-Print Network [OSTI]

    Fairey, P.; Vieira, R. K.; Parker, D. S.; Hanson, B.; Broman, P. A.; Grant, J. B.; Fuehrlein, B.; Gu, L.

    2002-01-01T23:59:59.000Z

    of EnergyGauge USA with significant impact on measures that effect sensible loads. The development of the new correlations is described in Henderson (1998a) and is based on empirical assessment of current generation heating and cooling equipment... moisture capacitance model for the simulation to damp out unrealistic variations in air enthalpy that were observed with the current model. The model, described in Henderson (1998b) assumes that the building has a moisture capacitance that is twenty...

  5. Molecular dynamics simulation of chains mobility in polyethylene crystal

    E-Print Network [OSTI]

    V. I. Sultanov; V. V. Atrazhev; D. V. Dmitriev; S. F. Burlatsky

    2014-01-17T23:59:59.000Z

    The mobility of polymer chains in perfect polyethylene (PE) crystal was calculated as a function of temperature and chain length through Molecular dynamics (MD) in united atom approximation. The results demonstrate that the chain mobility drastically increases in the vicinity of the phase transition from the orthorhombic to quasi-hexagonal phase. In the quasi-hexagonal phase, the chain mobility is almost independent on temperature and inversely proportional to the chain length.

  6. Helmet Streamers with Triple Structures: Simulations of resistive dynamics

    E-Print Network [OSTI]

    T. Wiegelmann; K. Schindler; T. Neukirch

    2008-01-21T23:59:59.000Z

    Recent observations of the solar corona with the LASCO coronagraph on board of the SOHO spacecraft have revealed the occurrence of triple helmet streamers even during solar minimum, which occasionally go unstable and give rise to large coronal mass ejections. There are also indications that the slow solar wind is either a combination of a quasi-stationary flow and a highly fluctuating component or may even be caused completely by many small eruptions or instabilities. As a first step we recently presented an analytical method to calculate simple two-dimensional stationary models of triple helmet streamer configurations. In the present contribution we use the equations of time- dependent resistive magnetohydrodynamics to investigate the stability and the dynamical behaviour of these configurations. We particularly focus on the possible differences between the dynamics of single isolated streamers and triple streamers and on the way in which magnetic reconnection initiates both small scale and large scale dynamical behaviour of the streamers. Our results indicate that small eruptions at the helmet streamer cusp may incessantly accelerate small amounts of plasma without significant changes of the equilibrium configuration and might thus contribute to the non-stationary slow solar wind. On larger time and length scales, large coronal eruptions can occur as a consequence of large scale magnetic reconnection events inside the streamer configuration. Our results also show that triple streamers are usually more stable than a single streamer.

  7. Simulation of aerosol dynamics: a comparative review of mathematical models

    SciTech Connect (OSTI)

    Seigneur, C.; Hudischewskyj, A.B.; Seinfeld, J.H.; Whitby, K.T.; Whitby, E.R.

    1986-01-01T23:59:59.000Z

    Three modeling approaches used are based-continuous, discrete (sectional), and parameterized representations of the aerosol size distribution. Simulations of coagulation and condensation are performed with the three models for clear, hazy, and urban atmospheric conditions. Relative accuracies and computational costs are compared. Reference for the comparison is the continuous approach. The results of the study provide useful information for the selection of an aerosol model, depending on the accuracy requirements and computational constraints associated with a specific application.

  8. Virtual control system environment: A modeling and simulation tool for process control systems

    SciTech Connect (OSTI)

    Lee, E.; Michalski, J.; Sholander, P.; Van Leeuwen, B. [Sandia National Laboratories, Albuquerque, NM 87111 (United States)

    2006-07-01T23:59:59.000Z

    The development of tools and techniques for security testing and performance testing of Process Control Systems (PCS) is needed since those systems are vulnerable to the same classes of threats as other networked computer systems. In practice, security testing is difficult to perform on operational PCS because it introduces an unacceptable risk of disruption to the critical systems (e.g., power grids) that they control. In addition, the hardware used in PCS is often expensive, making full-scale mockup systems for live experiments impractical. A more flexible approach to these problems can be provided through test beds that provide the proper mix of real, emulated, and virtual elements to model large, complex systems such as critical infrastructures. This paper describes a 'Virtual Control System Environment' that addresses these issues. (authors)

  9. Langevin dynamics simulations of biomolecules on graphics processors

    E-Print Network [OSTI]

    A. Zhmurov; R. I. Dima; Y. Kholodov; V. Barsegov

    2010-03-04T23:59:59.000Z

    Due to the very long timescales involved (us-s), theoretical modeling of fundamental biological processes including folding, misfolding, and mechanical unraveling of biomolecules, under physiologically relevant conditions, is challenging even for distributed computing systems. Graphics Processing Units (GPUs) are emerging as an alternative programming platform to the more traditional CPUs as they provide high raw computational power that can be utilized in a wide range of scientific applications. Using a coarse-grained Self Organized Polymer (SOP) model, we have developed and tested the GPU-based implementation of Langevin simulations for proteins (SOP-GPU program). Simultaneous calculation of forces for all particles is implemented using either the particle based or the interacting pair based parallelization, which leads to a ~30-fold acceleration compared to an optimized CPU version of the program. We assess the computational performance of an end-to-end application of the SOP-GPU program, where all steps of the algorithm are running on the GPU, by profiling the associated simulation time and memory usage for a number of small proteins, long protein fibers, and large-size protein assemblies. The SOP-GPU package can now be used in the theoretical exploration of the mechanical properties of large-size protein systems to generate the force-extension and force-indentation profiles under the experimental conditions of force application, and to relate the results of single-molecule experiments in vitro and in silico.

  10. Anomalous Scaling of Structure Functions and Dynamic Constraints on Turbulence Simulations

    E-Print Network [OSTI]

    Victor Yakhot; Katepalli R. Sreenivasan

    2005-06-20T23:59:59.000Z

    The connection between anomalous scaling of structure functions (intermittency) and numerical methods for turbulence simulations is discussed. It is argued that the computational work for direct numerical simulations (DNS) of fully developed turbulence increases as $Re^{4}$, and not as $Re^{3}$ expected from Kolmogorov's theory, where $Re$ is a large-scale Reynolds number. Various relations for the moments of acceleration and velocity derivatives are derived. An infinite set of exact constraints on dynamically consistent subgrid models for Large Eddy Simulations (LES) is derived from the Navier-Stokes equations, and some problems of principle associated with existing LES models are highlighted.

  11. Using dynamic simulations and automated decision tools to design lunar habitats

    E-Print Network [OSTI]

    Kortenkamp, David

    be useful for systems analyses much earlier in the system development life cycle than has previously been-time integrated control in designing and sizing habitat life support systems. The integration of these three implications for general systems analyses and for life support systems. It is likely that transient models

  12. Policy Strategies and Paths to promote Sustainable Energy Systems - The dynamic Invert Simulation Tool

    E-Print Network [OSTI]

    Stadler, Michael; Kranzl, Lukas; Huber, Claus; Haas, Reinhard; Tsioliaridou, Elena

    2006-01-01T23:59:59.000Z

    Schemes for sustainable energy systems”. InternationalPaths to promote Sustainable Energy Systems - The dynamicmoney - for promoting sustainable energy systems - be spent

  13. Policy Strategies and Paths to promote Sustainable Energy Systems - The dynamic Invert Simulation Tool

    E-Print Network [OSTI]

    Stadler, Michael; Kranzl, Lukas; Huber, Claus; Haas, Reinhard; Tsioliaridou, Elena

    2006-01-01T23:59:59.000Z

    strongly dominating the energy mix for heating in Vienna.premium) on the energy carrier mix, CO 2 reductions anddevelopment of the energy carrier mix is presented in Figure

  14. Policy Strategies and Paths to promote Sustainable Energy Systems - The dynamic Invert Simulation Tool

    E-Print Network [OSTI]

    Stadler, Michael; Kranzl, Lukas; Huber, Claus; Haas, Reinhard; Tsioliaridou, Elena

    2006-01-01T23:59:59.000Z

    grid comes from waste incineration and CHP. This supportsprimarily form waste incineration and gas CHP, the related

  15. Policy Strategies and Paths to promote Sustainable Energy Systems - The dynamic Invert Simulation Tool

    E-Print Network [OSTI]

    Stadler, Michael; Kranzl, Lukas; Huber, Claus; Haas, Reinhard; Tsioliaridou, Elena

    2006-01-01T23:59:59.000Z

    promotion of the use of bio-fuels or other renewable fuelsCHP, district heating, bio- fuels, solar thermal systems,electricity and transport (bio-fuel) sector till 2020. This

  16. Policy Strategies and Paths to promote Sustainable Energy Systems - The dynamic Invert Simulation Tool

    E-Print Network [OSTI]

    Stadler, Michael; Kranzl, Lukas; Huber, Claus; Haas, Reinhard; Tsioliaridou, Elena

    2006-01-01T23:59:59.000Z

    DSM, RES-E, RES-CHP, district heating, bio- fuels, solarcorresponding E.g. missing district heating grid, in urbanHeating plus DHW) dh district heating connection is in

  17. Policy Strategies and Paths to promote Sustainable Energy Systems - The dynamic Invert Simulation Tool

    E-Print Network [OSTI]

    Stadler, Michael; Kranzl, Lukas; Huber, Claus; Haas, Reinhard; Tsioliaridou, Elena

    2006-01-01T23:59:59.000Z

    solar thermal systems (30% for DHW systems; 40% for combined systems space heating and DHW). • Soft loans

  18. Impact of Resolution on Simulation of Closed Mesoscale Cellular Convection Identified by Dynamically Guided Watershed Segmentation

    SciTech Connect (OSTI)

    Martini, Matus; Gustafson, William I.; Yang, Qing; Xiao, Heng

    2014-11-27T23:59:59.000Z

    Organized mesoscale cellular convection (MCC) is a common feature of marine stratocumulus that forms in response to a balance between mesoscale dynamics and smaller scale processes such as cloud radiative cooling and microphysics. We use the Weather Research and Forecasting model with chemistry (WRF-Chem) and fully coupled cloud-aerosol interactions to simulate marine low clouds during the VOCALS-REx campaign over the southeast Pacific. A suite of experiments with 3- and 9-km grid spacing indicates resolution-dependent behavior. The simulations with finer grid spacing have smaller liquid water paths and cloud fractions, while cloud tops are higher. The observed diurnal cycle is reasonably well simulated. To isolate organized MCC characteristics we develop a new automated method, which uses a variation of the watershed segmentation technique that combines the detection of cloud boundaries with a test for coincident vertical velocity characteristics. This ensures that the detected cloud fields are dynamically consistent for closed MCC, the most common MCC type over the VOCALS-REx region. We demonstrate that the 3-km simulation is able to reproduce the scaling between horizontal cell size and boundary layer height seen in satellite observations. However, the 9-km simulation is unable to resolve smaller circulations corresponding to shallower boundary layers, instead producing invariant MCC horizontal scale for all simulated boundary layers depths. The results imply that climate models with grid spacing of roughly 3 km or smaller may be needed to properly simulate the MCC structure in the marine stratocumulus regions.

  19. Development and application of chemical tools for investigating dynamic processes in cell migration

    E-Print Network [OSTI]

    Goguen, Brenda Nicole

    2011-01-01T23:59:59.000Z

    Cell migration is a dynamic process essential for many fundamental physiological functions, including wound repair and the immune response. Migration relies on precisely orchestrated events that are regulated in a spatially ...

  20. Coupled Dynamic Analysis of Multiple Unit Floating Offshore Wind Turbine

    E-Print Network [OSTI]

    Bae, Yoon Hyeok

    2013-04-23T23:59:59.000Z

    In the present study, a numerical simulation tool has been developed for the rotor-floater-tether coupled dynamic analysis of Multiple Unit Floating Offshore Wind Turbine (MUFOWT) in the time domain including aero-blade-tower dynamics and control...

  1. A dynamic organic soil biogeochemical model for simulating the effects of wildfire on soil environmental

    E-Print Network [OSTI]

    Wagner, Diane

    of surface energy balance [Liu et al., 2005], soil thermal and hydrological regimes [MacKay, 1995; Burn, 1998A dynamic organic soil biogeochemical model for simulating the effects of wildfire on soil not comprehensively considered how interactions among fire disturbance, soil environmental conditions

  2. Interaction potentials for alumina and molecular dynamics simulations of amorphous and liquid alumina

    E-Print Network [OSTI]

    Southern California, University of

    Interaction potentials for alumina and molecular dynamics simulations of amorphous and liquid for preventing crystalliza- tion and giving chemical stability and durability to a glaze, for instance. Due been identified.4 A review of these crystal structures and their pre- cursors can be found in the work

  3. Dynamical chaos and critical behavior in Vlasov simulations of nuclear multifragmentation

    E-Print Network [OSTI]

    A. Atalmi; M. Baldo; G. F. Burgio; A. Rapisarda

    1996-02-26T23:59:59.000Z

    We discuss the presence of both dynamical chaos and signals of a second--order phase transition in numerical Vlasov simulations of nuclear multifragmentation. We find that chaoticity and criticality are strongly related and play a crucial role in the process of fragments formation. This connection is not limited to our model and seems a rather general feature.

  4. Molecular Dynamics Simulation of Amyloid b Dimer Formation B. Urbanc,* L. Cruz,* F. Ding,*y

    E-Print Network [OSTI]

    Stanley, H. Eugene

    of amyloid plaques. Hence, finding the conformation of these oligo- meric forms of Ab may be important; Thompson, 2003). The most common view is that Ab(1­40) and Ab(1­ 42) in fibrils form parallel bMolecular Dynamics Simulation of Amyloid b Dimer Formation B. Urbanc,* L. Cruz,* F. Ding,*y D

  5. Non-adiabatic molecular dynamics simulation of ultrafast solar cell electron transfer

    E-Print Network [OSTI]

    confinement devices [1­5]. Solar cells of the Graetzel type [6,7] are based on dye sensitized nanocrystalline in solar cells, photocatalysis and photoelectrolysis. The electronic structure of the dye cell; Ultrafast electron transfer; Non-adiabatic molecular dynamics simulation; Dye sensitized titanium

  6. Gas Phase Reaction with FT-ICR and Molecular Dynamics Simulation of Precursor Clusters for SWNTs

    E-Print Network [OSTI]

    Maruyama, Shigeo

    of the random cage delayed the annealing of the cage. Number of Carbon Atoms Intensity(arbitrary) NiC38 ­ CoC38 dynamics simulations of metal-containing carbon cluster formation were performed. Metal-carbon binary clusters were generated by the laser vaporization of Ni/Co or Ni/Y loaded carbon materials used

  7. Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Window Frames

    E-Print Network [OSTI]

    1 Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer Arasteh and Dragan Curcija ABSTRACT Accurately analyzing heat transfer in window frame cavities radiation heat-transfer effects.) We examine three representative complex cavity cross-section profiles

  8. Effect of the sliding orientation on the tribological properties of polyethylene in molecular dynamics simulations

    E-Print Network [OSTI]

    Sawyer, Wallace

    Effect of the sliding orientation on the tribological properties of polyethylene in molecular properties of polyethylene PE is investigated by using classical molecular dynamics simulations. Cross: 10.1063/1.2900884 I. INTRODUCTION Polyethylene PE is one of the most widely used poly- mers because

  9. The Value of Optimization in Dynamic Ride-Sharing: a Simulation Study in Metro Atlanta

    E-Print Network [OSTI]

    Erera, Alan

    of travelers per vehicle trip by effective usage of empty car seats by ride-sharing may of course enhance, and pollution. Moreover, ride-sharing allows users to share car-related expenses such as fuel costs. 1 #12;ByThe Value of Optimization in Dynamic Ride-Sharing: a Simulation Study in Metro Atlanta Niels Agatz

  10. Molecular Dynamics Simulation of Nucleation Process of Single-Walled Carbon Nanotubes

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Molecular Dynamics Simulation of Nucleation Process of Single-Walled Carbon Nanotubes YASUSHI SHIBUTA, SHIGEO MARUYAMA Nucleation process of single-walled carbon nanotubes by the catalytic chemical of a cap-structure of a nanotube. When the catalytic cluster reaches saturation with carbon atoms

  11. Precomputed Wave Simulation for Real-Time Sound Propagation of Dynamic Sources in Complex Scenes

    E-Print Network [OSTI]

    North Carolina at Chapel Hill, University of

    Precomputed Wave Simulation for Real-Time Sound Propagation of Dynamic Sources in Complex Scenes of North Carolina at Chapel Hill Abstract We present a method for real-time sound propagation that captures all wave effects, including diffraction and reverberation, for multi- ple moving sources and a moving

  12. Molecular Simulation of Multistate Peptide Dynamics: A Comparison Between Microsecond Timescale Sampling

    E-Print Network [OSTI]

    Sorin, Eric J.

    , Alberta T2N 1N4, Canada 2 Centre for Biomolecular Interdisciplinary Studies and Industrial ApplicationsMolecular Simulation of Multistate Peptide Dynamics: A Comparison Between Microsecond Timescale energy landscape and the kinetics of the equilibrium is high- lighted by principal component analysis

  13. Ecological Modelling 180 (2004) 135151 Simulating forest fuel and fire risk dynamics across

    E-Print Network [OSTI]

    He, Hong S.

    fuel module tracks fine fuel, coarse fuel and live fuel for each cell on a landscape. Fine fuel age (the oldest age cohorts) in combination with disturbance history. Live fuels, also called canopyEcological Modelling 180 (2004) 135­151 Simulating forest fuel and fire risk dynamics across

  14. Adaptive Accelerated ReaxFF Reactive Dynamics with Validation from Simulating Hydrogen Combustion

    E-Print Network [OSTI]

    Goddard III, William A.

    Adaptive Accelerated ReaxFF Reactive Dynamics with Validation from Simulating Hydrogen Combustion concept (BB), which we validate here for describing hydrogen combustion. The bond order, undercoordination determined the detailed sequence of reactions for hydrogen combustion with and without the BB. We validate

  15. Cooling energy demand evaluation by means of regression models obtained from dynamic simulations

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Cooling energy demand evaluation by means of regression models obtained from dynamic simulations Ph, Université Lyon1, FRANCE ABSTRACT The forecast of the energy heating/cooling demand would be a good indicator between simple and complex methods of evaluating the cooling energy demand we have proposed to use energy

  16. A Simple Interface to Computational Fluid Dynamics Programs for Building Environment Simulations

    E-Print Network [OSTI]

    Chen, Qingyan "Yan"

    . SCI can be easily integrated into new CFD programs. Introduction Advanced building design requests and pressure distributions that are crucial for thermal comfort and building structure designs. TraditionallyA Simple Interface to Computational Fluid Dynamics Programs for Building Environment Simulations

  17. Building Dynamic Models of Service Compositions With Simulation of Provision Resources

    E-Print Network [OSTI]

    Politécnica de Madrid, Universidad

    Building Dynamic Models of Service Compositions With Simulation of Provision Resources Dragan of service compositions depends both on the composition structure, and on planning and management of compu- tational resources necessary for provision. Resource constraints on the service provider side have impact

  18. The robust dynamical contribution to precipitation extremes in idealized warming simulations

    E-Print Network [OSTI]

    Chen, Gang

    The robust dynamical contribution to precipitation extremes in idealized warming simulations across shift under climate warming on the distribution of precipitation extremes and the associated sensitivity in the frequency of the most extreme categories of the precipitation events at the poleward side of the midlatitude

  19. Using regression equations to determine the relative importance of inputs to energy simulation tools

    SciTech Connect (OSTI)

    O'Neill, P.J.; Crawley, D.B.; Schliesing, J.S.

    1991-08-01T23:59:59.000Z

    A set of statistical regression equations was developed to predict relative heating and cooling loads of external zones of commercial buildings. The equations were derived from the coil loads predicted by several thousand DOE-2 simulations. These equations formed the basis for the building envelope criteria in ASHRAE/IES Standard 90.1-1989, Energy Efficient Design of New Commercial Buildings Except Low-Rise Residential Buildings.'' Because these equations predict relative loads, they can be used to determine the relative importance of a broad range of envelope parameters across a variety of climate types. This paper presents the procedure used to develop the equations. The relative importance of all the major loads input variables are discussed for a sample office building, for a broad range of climates. A load sensitivity analysis is then performed, which permits direct comparison of key envelope parameters. The analysis results provide general guidance to DOE-2 users as to the relative importance of specific loads input variables. 6 refs., 8 figs.

  20. Using femtosecond electron pulses as an imaging tool, we can probe ultrafast dynamics by taking snapshots at different time delays. By using femtosecond electron diffraction (FED),

    E-Print Network [OSTI]

    Weston, Ken

    Abstract Using femtosecond electron pulses as an imaging tool, we can probe ultrafast dynamics correlation. Additionally, ultrafast electron shadow imaging (UESI) can explore the dynamics of laser induced System The femtosecond "camera" mentioned above is comprised of an amplified femtosecond pulsed laser

  1. Molecular Dynamics Simulations of CO2 Formation in Interstellar Ices

    E-Print Network [OSTI]

    Arasa, Carina; van Dishoeck, Ewine F; Kroes, Geert-Jan

    2013-01-01T23:59:59.000Z

    CO2 ice is one of the most abundant components in ice-coated interstellar ices besides H2O and CO, but the most favorable path to CO2 ice is still unclear. Molecular dynamics calculations on the ultraviolet photodissociation of different kinds of CO-H2O ice systems have been performed at 10 K in order to demonstrate that the reaction between CO and an OH molecule resulting from H2O photodissociation through the first excited state is a possible route to form CO2 ice. However, our calculations, which take into account different ice surface models, suggest that there is another product with a higher formation probability ((3.00+-0.07)x10-2), which is the HOCO complex, whereas the formation of CO2 has a probability of only (3.6+-0.7)x10-4. The initial location of the CO is key to obtain reaction and form CO2: the CO needs to be located deep into the ice. The HOCO complex becomes trapped in the cold ice surface in the trans-HOCO minimum because it quickly loses its internal energy to the surrounding ice, preventi...

  2. Open systems dynamics: Simulating master equations in the computer

    E-Print Network [OSTI]

    Carlos Navarrete-Benlloch

    2015-04-21T23:59:59.000Z

    Master equations are probably the most fundamental equations for anyone working in quantum optics in the presence of dissipation. In this context it is then incredibly useful to have efficient ways of coding and simulating such equations in the computer, and in this notes I try to introduce in a comprehensive way how do I do so, focusing on Matlab, but making it general enough so that it can be directly translated to any other language or software of choice. I inherited most of my methods from Juan Jos\\'{e} Garc\\'{\\i}a-Ripoll (whose numerical abilities I cannot praise enough), changing them here and there to accommodate them to the way my (fairly limited) numerical brain works, and to connect them as much as possible to how I understand the theory behind them. At present, the notes focus on how to code master equations and find their steady state, but I hope soon I will be able to update them with time evolution methods, including how to deal with time-dependent master equations. During the last 4 years I've tested these methods in various different contexts, including circuit quantum electrodynamics, the laser problem, optical parametric oscillators, and optomechanical systems. Comments and (constructive) criticism are greatly welcome, and will be properly credited and acknowledged.

  3. Long-time protein folding dynamics from short-time molecular dynamics simulations

    E-Print Network [OSTI]

    Chodera, J D; Swope, W C; Pitera, J W; Dill, Ken A

    2006-01-01T23:59:59.000Z

    On the simulation of protein folding by short time scaleand W. A. Eaton, The protein folding “speed limit,” Curr.and T. Head-Gordon, Protein folding by distributed computing

  4. The VENUS/NWChem Software Package. Tight Coupling Between Chemical Dynamics Simulations and Electronic Structure Theory

    SciTech Connect (OSTI)

    Lourderaj, Upakarasamy; Sun, Rui; De Jong, Wibe A.; Windus, Theresa L.; Hase, William L.

    2014-03-01T23:59:59.000Z

    The interface for VENUS and NWChem, and the resulting software package for direct dynamics simulations are described. The coupling of the two codes is considered to be a tight coupling. The two codes are compiled and linked together and act as one executable with data being passed between the two codes through routine calls. The advantages of this type of coupling are discussed. The interface has been designed to have as little interference as possible with the core codes of both VENUS and NWChem. VENUS is the code that propagates the direct dynamics trajectories and, therefore, is the program that drives the overall execution of VENUS/NWChem. VENUS has remained an essentially sequential code, which uses the highly parallel structure of NWChem. Subroutines of the interface which accomplish the data transmission and communication between the two computer programs are described. Recent examples of the use of VENUS/NWChem for direct dynamics simulations are summarized.

  5. Molecular dynamics simulations of coherent optical photon emission from shock waves in Evan J. Reed,1,2,

    E-Print Network [OSTI]

    Soljaèiæ, Marin

    Molecular dynamics simulations of coherent optical photon emission from shock waves in crystals, 013904 2006 . In this work, we present analysis and molecular dynamics simulations of shock waves subject to a shock wave or solitonlike propagating excitation E. J. Reed et al., Phys. Rev. Lett. 96

  6. X-AND W-BAND EPR SPECTROSCOPY COMBINED WITH MOLECULAR DYNAMICS SIMULATIONS UNRAVEL THE STRUCTURE AND STRUCTURAL

    E-Print Network [OSTI]

    Steinhoff, Heinz-Jürgen

    X- AND W-BAND EPR SPECTROSCOPY COMBINED WITH MOLECULAR DYNAMICS SIMULATIONS UNRAVEL THE STRUCTURE (EPR) spectroscopy is combined with molecular dynamics (MD) simulations to study the structure and thus the EPR spectral line shape contain direct information about the secondary and tertiary structure

  7. Meridional circulation dynamics from 3D MHD global simulations of solar convection

    E-Print Network [OSTI]

    Passos, Dario; Miesch, Mark

    2015-01-01T23:59:59.000Z

    The form of the solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. Yet a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic techniques is challenging. In this work we use results from 3D global simulations of solar convection to infer the dynamical behavior of the established meridional circulation. We make a direct comparison between the meridional circulation that arises in these simulations and the latest observations. Based on our results we argue that there should be an equatorward flow at the base of the convection zone at mid latitudes, below the current maximum depth helioseismic measures can probe (0.75 R). We also provide physical arguments to justify this behaviour. The simulations indicate that the meridional circulation undergoes substantial changes in morphology as the magnetic cycle unfolds. We close by discussing the importance of these dynamical changes for current methods of obse...

  8. Quantum walks and quantum simulation of wavepacket dynamics with twisted photons

    E-Print Network [OSTI]

    Filippo Cardano; Francesco Massa; Hammam Qassim; Ebrahim Karimi; Sergei Slussarenko; Domenico Paparo; Corrado de Lisio; Fabio Sciarrino; Enrico Santamato; Robert W. Boyd; Lorenzo Marrucci

    2014-07-21T23:59:59.000Z

    The "quantum walk" has emerged recently as a paradigmatic process for the dynamic simulation of complex quantum systems, entanglement production and quantum computation. Hitherto, photonic implementations of quantum walks have mainly been based on multi-path interferometric schemes in real space. Here, we report the experimental realization of a discrete quantum walk taking place in the orbital angular momentum space of light, both for a single photon and for two simultaneous photons. In contrast to previous implementations, the whole process develops in a single light beam, with no need of interferometers; it requires optical resources scaling linearly with the number of steps; and it allows flexible control of input and output superposition states. Exploiting the latter property, we also simulated the quantum dynamics of Gaussian wavepackets, exploring the system dispersion relation in momentum space and the associated spin-orbit topological features. Our demonstration introduces a novel versatile photonic platform for quantum simulations.

  9. A parallel algorithm for transient solid dynamics simulations with contact detection

    SciTech Connect (OSTI)

    Attaway, S.; Hendrickson, B.; Plimpton, S.; Gardner, D.; Vaughan, C.; Heinstein, M.; Peery, J.

    1996-06-01T23:59:59.000Z

    Solid dynamics simulations with Lagrangian finite elements are used to model a wide variety of problems, such as the calculation of impact damage to shipping containers for nuclear waste and the analysis of vehicular crashes. Using parallel computers for these simulations has been hindered by the difficulty of searching efficiently for material surface contacts in parallel. A new parallel algorithm for calculation of arbitrary material contacts in finite element simulations has been developed and implemented in the PRONTO3D transient solid dynamics code. This paper will explore some of the issues involved in developing efficient, portable, parallel finite element models for nonlinear transient solid dynamics simulations. The contact-detection problem poses interesting challenges for efficient implementation of a solid dynamics simulation on a parallel computer. The finite element mesh is typically partitioned so that each processor owns a localized region of the finite element mesh. This mesh partitioning is optimal for the finite element portion of the calculation since each processor must communicate only with the few connected neighboring processors that share boundaries with the decomposed mesh. However, contacts can occur between surfaces that may be owned by any two arbitrary processors. Hence, a global search across all processors is required at every time step to search for these contacts. Load-imbalance can become a problem since the finite element decomposition divides the volumetric mesh evenly across processors but typically leaves the surface elements unevenly distributed. In practice, these complications have been limiting factors in the performance and scalability of transient solid dynamics on massively parallel computers. In this paper the authors present a new parallel algorithm for contact detection that overcomes many of these limitations.

  10. RAVEN AS A TOOL FOR DYNAMIC PROBABILISTIC RISK ASSESSMENT: SOFTWARE OVERVIEW

    SciTech Connect (OSTI)

    Alfonsi Andrea; Mandelli Diego; Rabiti Cristian; Joshua Cogliati; Robert Kinoshita

    2013-05-01T23:59:59.000Z

    RAVEN is a software tool under development at the Idaho National Laboratory (INL) that acts as the control logic driver and post-processing tool for the newly developed Thermo-Hydraylic code RELAP- 7. The scope of this paper is to show the software structure of RAVEN and its utilization in connection with RELAP-7. A short overview of the mathematical framework behind the code is presented along with its main capabilities such as on-line controlling/monitoring and Monte-Carlo sampling. A demo of a Station Black Out PRA analysis of a simplified Pressurized Water Reactor (PWR) model is shown in order to demonstrate the Monte-Carlo and clustering capabilities.

  11. Computational Particle Dynamic Simulations on Multicore Processors (CPDMu) Final Report â?? Phase I

    SciTech Connect (OSTI)

    Mark S. Schmalz

    2011-07-24T23:59:59.000Z

    Statement of Problem - Department of Energy has many legacy codes for simulation of computational particle dynamics and computational fluid dynamics applications that are designed to run on sequential processors and are not easily parallelized. Emerging high-performance computing architectures employ massively parallel multicore architectures (e.g., graphics processing units) to increase throughput. Parallelization of legacy simulation codes is a high priority, to achieve compatibility, efficiency, accuracy, and extensibility. General Statement of Solution - A legacy simulation application designed for implementation on mainly-sequential processors has been represented as a graph G. Mathematical transformations, applied to G, produce a graph representation {und G} for a high-performance architecture. Key computational and data movement kernels of the application were analyzed/optimized for parallel execution using the mapping G {yields} {und G}, which can be performed semi-automatically. This approach is widely applicable to many types of high-performance computing systems, such as graphics processing units or clusters comprised of nodes that contain one or more such units. Phase I Accomplishments - Phase I research decomposed/profiled computational particle dynamics simulation code for rocket fuel combustion into low and high computational cost regions (respectively, mainly sequential and mainly parallel kernels), with analysis of space and time complexity. Using the research team's expertise in algorithm-to-architecture mappings, the high-cost kernels were transformed, parallelized, and implemented on Nvidia Fermi GPUs. Measured speedups (GPU with respect to single-core CPU) were approximately 20-32X for realistic model parameters, without final optimization. Error analysis showed no loss of computational accuracy. Commercial Applications and Other Benefits - The proposed research will constitute a breakthrough in solution of problems related to efficient parallel computation of particle and fluid dynamics simulations. These problems occur throughout DOE, military and commercial sectors: the potential payoff is high. We plan to license or sell the solution to contractors for military and domestic applications such as disaster simulation (aerodynamic and hydrodynamic), Government agencies (hydrological and environmental simulations), and medical applications (e.g., in tomographic image reconstruction). Keywords - High-performance Computing, Graphic Processing Unit, Fluid/Particle Simulation. Summary for Members of Congress - Department of Energy has many simulation codes that must compute faster, to be effective. The Phase I research parallelized particle/fluid simulations for rocket combustion, for high-performance computing systems.

  12. Ab-initio molecular dynamics simulation of liquid water by Quantum Monte Carlo

    E-Print Network [OSTI]

    Andrea Zen; Ye Luo; Guglielmo Mazzola; Leonardo Guidoni; Sandro Sorella

    2014-12-09T23:59:59.000Z

    Despite liquid water is ubiquitous in chemical reactions at roots of life and climate on earth, the prediction of its properties by high-level ab initio molecular dynamics simulations still represents a formidable task for quantum chemistry. In this article we present a room temperature simulation of liquid water based on the potential energy surface obtained by a many-body wave function through quantum Monte Carlo (QMC) methods. The simulated properties are in excellent agreement with recent neutron scattering and X-ray experiments, particularly concerning the position of the oxygen-oxygen peak in the radial distribution function, at variance of previous Density Functional Theory attempts. Given the excellent performances of QMC on large scale supercomputers, this work opens new perspectives for predictive and reliable ab-initio simulations of complex chemical systems.

  13. Researchers at the National Renewable Energy Laboratory (NREL) develop a new complex modeling and analysis tool

    E-Print Network [OSTI]

    and analysis tool capable of analyzing floating platform concepts for offshore wind turbines. The new modeling tool combines the computational methodologies used to analyze land-based wind turbines dynamic simulation tool will enable the development of cost-effective offshore technologies capable

  14. Abstract--This paper describes a web-based electric power market simulation tool called POWERWEB. It can be used as an

    E-Print Network [OSTI]

    also be used very This work was supported in part by the Power Systems Engineering Research Center1 Abstract--This paper describes a web-based electric power market simulation tool called POWERWEB structure with the operational and reliability aspects of the underlying power system. Index Terms--Power

  15. The dynamic information architecture system : an advanced simulation framework for military and civilian applications.

    SciTech Connect (OSTI)

    Campbell, A. P.; Hummel, J. R.

    1998-01-08T23:59:59.000Z

    DIAS, the Dynamic Information Architecture System, is an object-oriented simulation system that was designed to provide an integrating framework in which new or legacy software applications can operate in a context-driven frame of reference. DIAS provides a flexible and extensible mechanism to allow disparate, and mixed language, software applications to interoperate. DIAS captures the dynamic interplay between different processes or phenomena in the same frame of reference. Finally, DIAS accommodates a broad range of analysis contexts, with widely varying spatial and temporal resolutions and fidelity.

  16. Probabilistic quantum phase-space simulation of Bell violations and their dynamical evolution

    E-Print Network [OSTI]

    Laura Rosales-Zárate; Bogdan Opanchuk; Peter D. Drummond; Margaret D. Reid

    2014-07-09T23:59:59.000Z

    Quantum simulations of Bell inequality violations are numerically obtained using probabilistic phase space methods, namely the positive P-representation. In this approach the moments of quantum observables are evaluated as moments of variables that have values outside the normal eigenvalue range. There is thus a parallel with quantum weak measurements and weak values. Nevertheless, the representation is exactly equivalent to quantum mechanics. A number of states violating Bell inequalities are sampled, demonstrating that these quantum paradoxes can be treated with probabilistic methods. We treat quantum dynamics by simulating the time evolution of the Bell state formed via parametric down-conversion, and discuss multi-mode generalizations.

  17. The computer BESK and an early attempt to simulate galactic dynamics

    E-Print Network [OSTI]

    Lindblad, Per Olof

    2015-01-01T23:59:59.000Z

    The first N-body simulation of interacting galaxies, even producing spiral arms, was performed by Erik Holmberg in Lund (1941), not with a numerical computer, but by his arrangement of movable light-bulbs and photocells to measure the luminosity at each bulb and thereby estimate the gravitational force. A decade later, and with the arrival of the first programable computers, computations of galactic dynamics were performed, which were later transferred into a N-body simulation movie. I present here the background details for this work with a description of the important elements to note in the movie which may be retrieved at http://ttt.astro.su.se/~po .

  18. On the modeling and simulation of of reaction-transfer dynamics in semiconductor-electrolyte solar cells

    E-Print Network [OSTI]

    -performance semiconductor-liquid junction solar cells. We propose in this work a macroscopic mathematical model, a sys- tem-liquid junction, solar cell simulation, naso-scale device modeling. 1 Introduction The mathematical modeling by the increasing need of simulation tools for designing efficient solar cells to harvest sunlight for clean energy

  19. Efficient Molecular Dynamics Simulations of Multiple Radical Center Systems Based on the Fragment Molecular Orbital Method

    SciTech Connect (OSTI)

    Nakata, Hiroya [Tokyo Institute of Technology; Schmidt, Michael W [Ames Laboratory; Fedorov, Dmitri G [National Institute of Advanced Industrial Science and Technology (AIST); Kitaura, Kazuo [Kobe University; Nakamura, Shinichiro [Nakamura Lab; Gordon, Mark S [Ames Laboratory

    2014-10-16T23:59:59.000Z

    The fully analytic energy gradient has been developed and implemented for the restricted open-shell Hartree–Fock (ROHF) method based on the fragment molecular orbital (FMO) theory for systems that have multiple open-shell molecules. The accuracy of the analytic ROHF energy gradient is compared with the corresponding numerical gradient, illustrating the accuracy of the analytic gradient. The ROHF analytic gradient is used to perform molecular dynamics simulations of an unusual open-shell system, liquid oxygen, and mixtures of oxygen and nitrogen. These molecular dynamics simulations provide some insight about how triplet oxygen molecules interact with each other. Timings reveal that the method can calculate the energy gradient for a system containing 4000 atoms in only 6 h. Therefore, it is concluded that the FMO-ROHF method will be useful for investigating systems with multiple open shells.

  20. Simulation of aerosol dynamics: A comparative review of algorithms used in air quality models

    SciTech Connect (OSTI)

    Zhang, Y.; Seigneur, C.; Seinfeld, J.H.; Jacobson, M.Z.; Binkowski, F.S.

    1999-01-01T23:59:59.000Z

    A comparative review of algorithms currently used in air quality models to simulate aerosol dynamics is presented. This review addresses coagulation, condensational growth, nucleation, and gas/particle mass transfer. Two major approaches are used in air quality models to represent the particle size distribution: (1) the sectional approach in which the size distribution is discretized into sections and particle properties are assumed to be constant over particle size sections and (2) the modal approach in which the size distribution is approximated by several modes and particle properties are assumed to be uniform in each mode. The results of this study provide useful information to select algorithms to simulate aerosol dynamics in air quality models and to improve the accuracy of existing algorithms.

  1. A framework for simulating and estimating the state and functional topology of complex dynamic geometric networks

    E-Print Network [OSTI]

    Marius Buibas; Gabriel A. Silva

    2010-06-22T23:59:59.000Z

    We present a framework for simulating signal propagation in geometric networks (i.e. networks that can be mapped to geometric graphs in some space) and for developing algorithms that estimate (i.e. map) the state and functional topology of complex dynamic geometric net- works. Within the framework we define the key features typically present in such networks and of particular relevance to biological cellular neural networks: Dynamics, signaling, observation, and control. The framework is particularly well-suited for estimating functional connectivity in cellular neural networks from experimentally observable data, and has been implemented using graphics processing unit (GPU) high performance computing. Computationally, the framework can simulate cellular network signaling close to or faster than real time. We further propose a standard test set of networks to measure performance and compare different mapping algorithms.

  2. Spin Dynamics Simulations of Multiple Echo Spacing Pulse Sequences in Grossly Inhomogeneous Fields

    SciTech Connect (OSTI)

    Heidler, R.; Bachman, H. N.; Johansen, Y. [Schlumberger Oilfield Services, Sugar Land, TX 77478 (United States)

    2008-12-05T23:59:59.000Z

    Pulse sequences with multiple lengths of echo spacings are used in oilfield NMR logging for diffusion-based NMR applications such as rock and fluid characterization. One specific implementation is the so-called diffusion editing sequence comprising two long echo spacings followed by a standard CPMG at a shorter echo spacing. The echoes in the CPMG portion contain signal from both the direct and stimulated echoes.Modern oilfield NMR logging tools are designed for continuous depth logging of earth formations by projecting both the static (B{sub 0}) and dynamic (B{sub 1}) fields into the formation. Both B{sub 0} and B{sub 1} profiles are grossly inhomogeneous which results in non-steady-state behavior in the early echoes. The spin dynamics effects present a challenge for processing the echo amplitudes to measure porosity (amplitude extrapolated to zero time) and attenuations for fluid or pore size characterization.In this work we describe a calculation of the spin dynamics of the diffusion editing sequence with two long echo spacings. The calculation takes into account full B{sub 1} and B{sub 0} field maps, and comparisons will be made for sensors and parameters typical of oilfield logging tools and environments.

  3. Ultrapdeep water blowouts: COMASim dynamic kill simulator validation and best practices recommendations

    E-Print Network [OSTI]

    Noynaert, Samuel F.

    2005-02-17T23:59:59.000Z

    64 3 14 30 6 8 4 3 180 Total 26.7% 35.6% 1.7% 7.8% 16.7% 3.3% 4.4% 2.2% 1.7% 100.0% * External causes are typical; storm, military activity, ship collision, fire and earthquake. Fig. 1.10 clearly shows the most blowouts occur... 1 ULTRADEEP WATER BLOWOUTS: COMASIM DYNAMIC KILL SIMULATOR VALIDATION AND BEST PRACTICES RECOMMENDATIONS A Thesis by SAMUEL F. NOYNAERT...

  4. A Gaussian process-based approach for handling uncertainty in vehicle dynamics simulation.

    SciTech Connect (OSTI)

    Schmitt, K.; Madsen, J.; Anitescu, M.; Negrut, D.; Mathematics and Computer Science; Univ. of Wisconsin at Madison

    2009-01-01T23:59:59.000Z

    Advances in vehicle modeling and simulation in recent years have led to designs that are safer, easier to handle, and less sensitive to external factors. Yet, the potential of simulation is adversely impacted by its limited ability to predict vehicle dynamics in the presence of uncertainty. A commonly occurring source of uncertainty in vehicle dynamics is the road-tire friction interaction, typically represented through a spatially distributed stochastic friction coefficient. The importance of its variation becomes apparent on roads with ice patches, where if the stochastic attributes of the friction coefficient are correctly factored into real time dynamics simulation, robust control strategies could be designed to improve transportation safety. This work concentrates on correctly accounting in the nonlinear dynamics of a car model for the inherent uncertainty in friction coefficient distribution at the road/tire interface. The outcome of this effort is the ability to quantify the effect of input uncertainty on a vehicle's trajectory and the associated escalation of risk in driving. By using a space-dependent Gaussian process, the statistical representation of the friction coefficient allows for consistent space dependence of randomness. The approach proposed allows for the incorporation of noise in the observed data and a nonzero mean for inhomogeneous distribution of the friction coefficient. Based on the statistical model considered, consistent friction coefficient sample distributions are generated over large spatial domains of interest. These samples are subsequently used to compute and characterize the statistics associated with the dynamics of a nonlinear vehicle model. The information concerning the state of the road and thus the friction coefficient is assumed available (measured) at a limited number of points by some sensing device that has a relatively homogeneous noise field (satellite picture or ground sensors, for instance). The methodology proposed can be modified to incorporate information that is sensed by each individual car as it advances along its trajectory.

  5. Using Simulations and kinetic network models to reveal the dynamics and functions of Riboswitches

    E-Print Network [OSTI]

    Jong-Chin Lin; Jeseong Yoon; Changbong Hyeon; D. Thirumalai

    2014-10-02T23:59:59.000Z

    Riboswitches, RNA elements found in the untranslated region, regulate gene expression by binding to target metaboloites with exquisite specificity. Binding of metabolites to the conserved aptamer domain allosterically alters the conformation in the downstream expression platform. The fate of gene expression is determined by the changes in the downstream RNA sequence. As the metabolite-dependent cotranscriptional folding and unfolding dynamics of riboswitches is the key determinant of gene expression, it is important to investigate both the thermodynamics and kinetics of riboswitches both in the presence and absence of metabolite. Single molecule force experiments that decipher the free energy landscape of riboswitches from their mechanical responses, theoretical and computational studies have recently shed light on the distinct mechanism of folding dynamics in different classes of riboswitches. Here we first discuss the dynamics of water around riboswitch, highlighting that water dynamics can enhance the fluctuation of nucleic acid structure. To go beyond native state fluctuations we used the Self-Organized Polymer (SOP) model to predict the dynamics of add adenine riboswitch under mechanical forces. In addition to quantitatively predicting the folding landscape of add-riboswitch our simulations also explain the difference in the dynamics between pbuE adenine- and add adenine-riboswitches. In order to probe the function {\\it in vivo} we use the folding landscape to propose a system level kinetic network model to quantitatively predict how gene expression is regulated for riboswitches that are under kinetic control.

  6. Molecular Dynamic Simulation of Sodium in 7-Pin LMFBR Bundle Under Hypothetical Accident Conditions

    SciTech Connect (OSTI)

    Bottoni, Maurizio [University of Ferrara, Physics Department, Via Paradiso 12, I-44100 Ferrara (Italy); Bottoni, Claudio; Scanu, John [University of Pisa, Lungarno Pacinotti, 43 - 56126 Pisa (Italy)

    2006-07-01T23:59:59.000Z

    In the frame of safety analysis of liquid metal fast breeder reactors (LMFBRs) under hypothetical Unprotected Loss of Flow (ULOF) conditions two-phase flow of sodium is simulated in a 7-pin bundle, with hexagonal lattice. Molecular dynamics, with the application of the Direct Simulation Monte Carlo (DSMC) method, and a macroscopic model describing rewetting sequences due to the flow of a sodium liquid film along the pin surfaces, are applied to simulate the coolant in the bundle. The pin surfaces and the inner surface of the hexagonal canning are treated in the Monte Carlo simulation as diffusively reflecting surfaces. Collisions of sodium molecules are computed with the 'hard-sphere' model. With respect to previous work the following improvements of the computational code were made: i) The full bundle is simulated, thus allowing for asymmetries, like a skewed power distribution, to be accounted for; ii) A pin model calculates detailed temperature distributions in the pins, so that temperature boundary conditions are computed and not imposed; iii) Post processing visualisation of computed results was developed. An out of pile sodium boiling experiment run at the Nuclear Research Center of Karlsruhe, Germany, is simulated and conclusions are drawn about the applicability of the methodology in computer codes dedicated to breeder reactors safety analysis. (authors)

  7. Computer simulation study of surface wave dynamics at the crystal--melt interface

    E-Print Network [OSTI]

    Jorge Benet; Luis G. MacDowell; Eduardo Sanz

    2014-10-01T23:59:59.000Z

    We study, by means of computer simulations, the crystal-melt interface of three different systems: hard-spheres, Lennard Jones and the TIP4P/2005 water model. In particular, we focus on the dynamics of surface waves. We observe that the processes involved in the relaxation of surface waves are characterized by distinct time scales: a slow one related to the continuous recrystallization and melting, that is governed by capillary forces; and a fast one which we suggest to be due to a combination of processes that quickly cause small perturbations to the shape of the interface (like e. g. Rayleigh waves, subdiffusion, or attachment/detachment of particles to/from the crystal). The relaxation of surface waves becomes dominated by the slow process as the wavelength increases. Moreover, we see that the slow relaxation is not influenced by the details of the microscopic dynamics. In a time scale characteristic for the diffusion of the liquid phase, the relaxation dynamics of the crystal-melt interface of water is around one order of magnitude slower than that of Lennard Jones or hard spheres, which we ascribe to the presence of orientational degrees of freedom in the water molecule. Finally, we estimate the rate of crystal growth from our analysis of the capillary wave dynamics and compare it with previous simulation studies and with experiments for the case of water.

  8. A molecular dynamics simulation of DNA damage induction by ionizing radiation

    E-Print Network [OSTI]

    Abolfath, Ramin M; Chen, Zhe J; Nath, Ravinder

    2013-01-01T23:59:59.000Z

    We present a multi-scale simulation of early stage of DNA damages by the indirect action of hydroxyl ($^\\bullet$OH) free radicals generated by electrons and protons. The computational method comprises of interfacing the Geant4-DNA Monte Carlo with the ReaxFF molecular dynamics software. A clustering method was employed to map the coordinates of $^\\bullet$OH-radicals extracted from the ionization track-structures onto nano-meter simulation voxels filled with DNA and water molecules. The molecular dynamics simulation provides the time evolution and chemical reactions in individual simulation voxels as well as the energy-landscape accounted for the DNA-$^\\bullet$OH chemical reaction that is essential for the first principle enumeration of hydrogen abstractions, chemical bond breaks, and DNA-lesions induced by collection of ions in clusters less than the critical dimension which is approximately 2-3 \\AA. We show that the formation of broken bonds leads to DNA base and backbone damages that collectively propagate ...

  9. An adaptively refined phase-space element method for cosmological simulations and collisionless dynamics

    E-Print Network [OSTI]

    Hahn, Oliver

    2015-01-01T23:59:59.000Z

    Dark matter numerical simulations and the N-body method are essential for understanding how structure forms and evolves in the Universe. However, the discrete nature of N-body simulations can affect its accuracy when modelling collisionless systems. We introduce a new approach to simulate the gravitational evolution of cold collisionless fluids by solving the Vlasov-Poisson equations in terms of adaptively refineable "Lagrangian phase space elements". These geometrical elements are piecewise smooth maps between three-dimensional Lagrangian space and six-dimensional Eulerian phase space and approximate the continuum structure of the distribution function. They allow for dynamical adaptive splitting to follow the evolution even in regions of very strong mixing. We discuss various test problems which demonstrate the correctness and performance of our method. We show that it has several advantages compared to standard N-body algorithms by i) explicitly tracking the fine-grained distribution function, ii) naturall...

  10. Molecular dynamics simulation of complex molecules at interfaces: dendritic surfactants in clay and amyloid peptides near lipid bilayers

    E-Print Network [OSTI]

    Han, Kunwoo

    2009-06-02T23:59:59.000Z

    We apply a molecular dynamics (MD) simulation technique to complex molecules at interfaces. Partitioning of dendritic surfactants into clay gallery and Ab protein behavior near hydrated lipids are chosen for the purpose. Using a full atomistic model...

  11. Influence of temperature and viscosity on anthracene rotational diffusion in organic solvents: Molecular dynamics simulations and fluorescence anisotropy study

    E-Print Network [OSTI]

    Jas, Gouri S.; Wang, Yan; Pauls, Steven W.; Johnson, Carey K.; Kuczera, Krzysztof

    1997-01-01T23:59:59.000Z

    Molecular dynamics simulations and fluorescenceanisotropy decay measurements are used to investigate the rotational diffusion of anthracene in two organic solvents—cyclohexane and 2-propanol—at several temperatures. Molecular ...

  12. The Molecular Structure of a Phosphatidylserine Bilayer Determined by Scattering and Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    Pan, Jianjun [University of South Florida, Tampa (USF)] [University of South Florida, Tampa (USF); Cheng, Xiaolin [ORNL] [ORNL; Monticelli, Luca [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France] [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France; Heberle, Frederick A [ORNL] [ORNL; Kucerka, Norbert [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,] [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,; Tieleman, D. Peter [University of Calgary, ALberta, Canada] [University of Calgary, ALberta, Canada; Katsaras, John [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    Phosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 A2 at 25 C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger KA than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions.

  13. Interfacial water on crystalline silica: A comparative molecular dynamics simulation study

    SciTech Connect (OSTI)

    Ho, Tuan A. [University of Oklahoma, Norman; Argyris, D. [University of Oklahoma, Norman; Cole, David [Ohio State University; Striolo, Alberto [Oklahoma University

    2011-01-01T23:59:59.000Z

    All-atom molecular dynamics simulations were conducted to study the dynamics of aqueous electrolyte solutions confined in slit-shaped silica nanopores of various degrees of protonation. Five degrees of protonation were prepared by randomly removing surface hydrogen atoms from fully protonated crystalline silica surfaces. Aqueous electrolyte solutions containing NaCl or CsCl salt were simulated at ambient conditions. In all cases, the ionic concentration was 1 M. The results were quantified in terms of atomic density distributions within the pores, and the self-diffusion coefficient along the direction parallel to the pore surface. We found evidence for ion-specific properties that depend on ion surface, water ion, and only in some cases ion ion correlations. The degree of protonation strongly affects the structure, distribution, and the dynamic behavior of confined water and electrolytes. Cl ions adsorb on the surface at large degrees of protonation, and their behavior does not depend significantly on the cation type (either Na+ or Cs+ ions are present in the systems considered). The cations show significant ion-specific behavior. Na+ ions occupy different positions within the pore as the degree of protonation changes, while Cs+ ions mainly remain near the pore center at all conditions considered. For a given degree of protonation, the planar self-diffusion coefficient of Cs+ is always greater than that of Na+ ions. The results are useful for better understanding transport under confinement, including brine behavior in the subsurface, with important applications such as environmental remediation.

  14. Modeling, simulation, and testing of the mechanical dynamics of and RF MEMS switch.

    SciTech Connect (OSTI)

    Sumali, Hartono; Epp, David S.; Massad, Jordan Elias; Dyck, Christopher William; Starr, Michael James

    2005-07-01T23:59:59.000Z

    Mechanical dynamics can be a determining factor for the switching speed of radio-frequency microelectromechanical systems (RF MEMS) switches. This paper presents the simulation of the mechanical motion of a microswitch under actuation. The switch has a plate suspended by springs. When an electrostatic actuation is applied, the plate moves toward the substrate and closes the switch. Simulations are calculated via a high-fidelity finite element model that couples solid dynamics with electrostatic actuation. It incorporates non-linear coupled dynamics and accommodates fabrication variations. Experimental modal analysis gives results in the frequency domain that verifies the natural frequencies and mode shapes predicted by the model. An effective 1D model is created and used to calculate an actuation voltage waveform that minimizes switch velocity at closure. In the experiment, the switch is actuated with this actuation voltage, and the displacements of the switch at various points are measured using a laser Doppler velocimeter through a microscope. The experiments are repeated on several switches from different batches. The experimental results verify the model.

  15. Spin dynamics simulation of electron spin relaxation in Ni{sup 2+}(aq)

    SciTech Connect (OSTI)

    Rantaharju, Jyrki, E-mail: jjrantaharju@gmail.com; Mareš, Ji?í, E-mail: jiri.mares@oulu.fi; Vaara, Juha, E-mail: juha.vaara@iki.fi [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014 (Finland)

    2014-07-07T23:59:59.000Z

    The ability to quantitatively predict and analyze the rate of electron spin relaxation of open-shell systems is important for electron paramagnetic resonance and paramagnetic nuclear magnetic resonance spectroscopies. We present a combined molecular dynamics (MD), quantum chemistry (QC), and spin dynamics simulation method for calculating such spin relaxation rates. The method is based on the sampling of a MD trajectory by QC calculations, to produce instantaneous parameters of the spin Hamiltonian used, in turn, to numerically solve the Liouville-von Neumann equation for the time evolution of the spin density matrix. We demonstrate the approach by simulating the relaxation of electron spin in an aqueous solution of Ni{sup 2+} ion. The spin-lattice (T{sub 1}) and spin-spin (T{sub 2}) relaxation rates are extracted directly from the simulations of the time dependence of the longitudinal and transverse magnetization, respectively. Good agreement with the available, indirectly obtained experimental data is obtained by our method.

  16. Numerical Simulation of Squeeze Film Dampers and Study of the Effect of Central Groove on the Dynamic Pressure Distribution

    E-Print Network [OSTI]

    Boppa, Praneetha

    2012-10-19T23:59:59.000Z

    . The behavior of dynamic pressure profiles at different operating conditions, and the effect of a central groove on dynamic pressure profiles were also studied. Simulation results of a 3D case which is similar to the one experimentally studied by Delgado were...

  17. Fast and Informative Flow Simulations in a Building by Using Fast Fluid Dynamics Model on Graphics Processing Unit

    E-Print Network [OSTI]

    Chen, Qingyan "Yan"

    Fast and Informative Flow Simulations in a Building by Using Fast Fluid Dynamics Model on Graphics solve Navier-Stokes equations and other transportation equations for energy and species at a speed of 50 it in parallel on a Graphics Processing Unit (GPU). This study validated the FFD on the GPU by simulating

  18. Leveraging on Easy Java Simulation tool and open source computer simulation library to create interactive digital media for mass customization of high school physics curriculum

    E-Print Network [OSTI]

    Wee, Loo Kang

    2012-01-01T23:59:59.000Z

    This paper highlights the diverse possibilities in the rich community of educators from the Conceptual Learning of Science (CoLoS) and Open Source Physics (OSP) movement to engage, enable and empower educators and students, to create interactive digital media through computer modeling. This concept revolves around a paradigmatic shift towards participatory learning through immersive computer modeling, as opposed to using technology for information transmission. We aim to engage high school educators to professionally develop themselves by creating and customizing simulations possible through Easy Java Simulation (Ejs) and its learning community. Ejs allows educators to be designers of learning environments through modifying source codes of the simulation. Educators can conduct lessons with students' using these interactive digital simulations and rapidly enhance the simulation through changing the source codes personally. Ejs toolkit, its library of simulations and growing community contributed simulation cod...

  19. Canonicalization and symplectic simulation of the gyrocenter dynamics in time-independent magnetic fields

    SciTech Connect (OSTI)

    Zhang, Ruili; Tang, Yifa; Zhu, Beibei [LSEC, ICMSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China)] [LSEC, ICMSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Jian, E-mail: jliuphy@ustc.edu.cn; Xiao, Jianyuan [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Qin, Hong [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China) [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

    2014-03-15T23:59:59.000Z

    The gyrocenter dynamics of charged particles in time-independent magnetic fields is a non-canonical Hamiltonian system. The canonical description of the gyrocenter has both theoretical and practical importance. We provide a general procedure of the gyrocenter canonicalization, which is expressed by the series of a small variable ? depending only on the parallel velocity u and can be expressed in a recursive manner. We prove that the truncation of the series to any given order generates a set of exact canonical coordinates for a system, whose Lagrangian approximates to that of the original gyrocenter system in the same order. If flux surfaces exist for the magnetic field, the series stops simply at the second order and an exact canonical form of the gyrocenter system is obtained. With the canonicalization schemes, the canonical symplectic simulation of gyrocenter dynamics is realized for the first time. The canonical symplectic algorithm has the advantage of good conservation properties and long-term numerical accuracy, while avoiding numerical instability. It is worth mentioning that explicitly expressing the canonical Hamiltonian in new coordinates is usually difficult and impractical. We give an iteration procedure that is easy to implement in the original coordinates associated with the coordinate transformation. This is crucial for modern large-scale simulation studies in plasma physics. The dynamics of gyrocenters in the dipole magnetic field and in the toroidal geometry are simulated using the canonical symplectic algorithm by comparison with the higher-order non symplectic Runge-Kutta scheme. The overwhelming superiorities of the symplectic method for the gyrocenter system are evidently exhibited.

  20. Numerical simulation of the stochastic dynamics of inclusions in biomembranes in presence of surface tension

    E-Print Network [OSTI]

    H. Rafii-Tabar; H. R. Sepangi

    2005-08-30T23:59:59.000Z

    The stochastic dynamics of inclusions in a randomly fluctuating biomembrane is simulated. These inclusions can represent the embedded proteins and the external particles arriving at a cell membrane. The energetics of the biomembrane is modelled via the Canham-Helfrich Hamiltonian. The contributions of both the bending elastic-curvature energy and the surface tension of the biomembrane are taken into account. The biomembrane is treated as a two-dimensional sheet whose height variations from a reference frame is treated as a stochastic Wiener process. The lateral diffusion parameter associated with this Wiener process coupled with the longitudinal diffusion parameter obtained from the standard Einsteinian diffusion theory completely determine the stochastic motion of the inclusions. It is shown that the presence of surface tension significantly affects the overall dynamics of the inclusions, particularly the rate of capture of the external inclusions, such as drug particles, at the site of the embedded inclusions, such as the embedded proteins.

  1. Quantum molecular dynamics simulation of shock-wave experiments in aluminum

    SciTech Connect (OSTI)

    Minakov, D. V.; Khishchenko, K. V.; Fortov, V. E. [Joint Institute for High Temperatures RAS, Izhorskaya 13 Bldg 2, Moscow 125412 (Russian Federation); Moscow Institute of Physics and Technology, Institutskii per. 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); Levashov, P. R. [Joint Institute for High Temperatures RAS, Izhorskaya 13 Bldg 2, Moscow 125412 (Russian Federation); Tomsk State University, 36 Lenin Prospekt, Tomsk 634050 (Russian Federation)

    2014-06-14T23:59:59.000Z

    We present quantum molecular dynamics calculations of principal, porous, and double shock Hugoniots, release isentropes, and sound velocity behind the shock front for aluminum. A comprehensive analysis of available shock-wave data is performed; the agreement and discrepancies of simulation results with measurements are discussed. Special attention is paid to the melting region of aluminum along the principal Hugoniot; the boundaries of the melting zone are estimated using the self-diffusion coefficient. Also, we make a comparison with a high-quality multiphase equation of state for aluminum. Independent semiempirical and first-principle models are very close to each other in caloric variables (pressure, density, particle velocity, etc.) but the equation of state gives higher temperature on the principal Hugoniot and release isentropes than ab initio calculations. Thus, the quantum molecular dynamics method can be used for calibration of semiempirical equations of state in case of lack of experimental data.

  2. Driving Down HB-LED Costs: Implementation of Process Simulation Tools and Temperature Control Methods of High Yield MOCVD Growth

    SciTech Connect (OSTI)

    William Quinn

    2012-04-30T23:59:59.000Z

    The overall objective of this multi-faceted program is to develop epitaxial growth systems that meet a goal of 75% (4X) cost reduction in the epitaxy phase of HB-LED manufacture. A 75% reduction in yielded epitaxy cost is necessary in order to achieve the cost goals for widespread penetration of HB-LEDâ??s into back-lighting units (BLU) for LCD panels and ultimately for solid-state lighting (SSL). To do this, the program will address significant improvements in overall equipment Cost of Ownership, or CoO. CoO is a model that includes all costs associated with the epitaxy portion of production. These aspects include cost of yield, capital cost, operational costs, and maintenance costs. We divide the program into three phases where later phases will incorporate the gains of prior phases. Phase one activities are enabling technologies. In collaboration with Sandia National Laboratories we develop a Fluent-compatible chemistry predictive model and a set of mid-infrared and near-ultraviolet pyrometer monitoring tools. Where previously the modeling of the reactor dynamics were studied within FLUENT alone, here, FLUENT and Chemkin are integrated into a comprehensive model of fluid dynamics and the most advanced transport equations developed for Chemkin. Specifically, the Chemkin model offered the key reaction terms for gas-phase nucleation, a key consideration in the optimization of the MOCVD process. This new predictive model is used to design new MOCVD reactors with optimized growth conditions and the newly developed pyrometers are used monitor and control the MOCVD process temperature to within 0.5°C run-to-run and within each wafer. This portion of the grant is in collaboration with partners at Sandia National Laboratories. Phase two activities are continuous improvement projects which extend the current reactor platform along the lines of improved operational efficiency, improved systems control for throughput, and carrier modifications for increased yield. Programmatically, improvements made in Phase I are applied to developments of Phase II when applicable. Phase three is the culmination of the individual tasks from both phases one and two applied to proposed production platforms. We selectively combine previously demonstrated tasks and other options to develop a high-volume production-worthy MOCVD system demonstrating >3x throughput, 1.3x capital efficiency, and 0.7x cost of ownership. In a parallel demonstration we validate the concept of an improved, larger deposition system which utilizes the predictive modeling of chemistry-based flow analysis and extensions of the improvements demonstrated on the current platforms. This validation includes the build and testing of a prototype version of the hardware and demonstration of 69% reduction in the cost of ownership. Also, in this phase we present a stand-alone project to develop a high-temperature system which improves source efficiency by 30% while concurrently increasing growth rate by 1.3x. The material quality is held to the same material quality specifications of our existing baseline processes. The merits of other line item tasks in phase three are discussed for inclusion on next-generation platforms.

  3. Temperature-dependent mechanical properties of single-layer molybdenum disulphide: Molecular dynamics nanoindentation simulations

    SciTech Connect (OSTI)

    Zhao, Junhua, E-mail: junhua.zhao@uni-weimar.de [Jiangsu Province Key Laboratory of Advanced Manufacturing Equipment and Technology of Food, Jiangnan University, 214122 Wuxi (China) [Jiangsu Province Key Laboratory of Advanced Manufacturing Equipment and Technology of Food, Jiangnan University, 214122 Wuxi (China); Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); Jiang, Jin-Wu, E-mail: jwjiang5918@hotmail.com [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany)] [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); Rabczuk, Timon, E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany) [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, 136-701 Seoul (Korea, Republic of)

    2013-12-02T23:59:59.000Z

    The temperature-dependent mechanical properties of single-layer molybdenum disulphide (MoS{sub 2}) are obtained using molecular dynamics (MD) nanoindentation simulations. The Young's moduli, maximum load stress, and maximum loading strain decrease with increasing temperature from 4.2?K to 500?K. The obtained Young's moduli are in good agreement with those using our MD uniaxial tension simulations and the available experimental results. The tendency of maximum loading strain with different temperature is opposite with that of metal materials due to the short range Stillinger-Weber potentials in MoS{sub 2}. Furthermore, the indenter tip radius and fitting strain effect on the mechanical properties are also discussed.

  4. Analog and digital dynamic simulations of a rigid body aircraft in straight and level flight

    E-Print Network [OSTI]

    Stroman, Morris Michael

    1973-01-01T23:59:59.000Z

    . , Texas A&M University Directed by: Dr. Balusu M. Rao A study of the dynamic response characteristics of an aircraft at low approach speeds was conducted using both a digital and an analog computer to simulate a DeHavilland "Beaver" DHC-2 in flight... to produce more sideslip and yawing motions than the rudder with analytical solutions. The problem areas of the STOL aircraft at low approach speeds as a result of a study of the DeHavilland "Beaver" were in lateral stability. The aircraft's response...

  5. Solvent-Driven Preferential Association of Lignin with Regions of Crystalline Cellulose in Molecular Dynamics Simulation

    SciTech Connect (OSTI)

    Lindner, Benjamin [ORNL] [ORNL; Petridis, Loukas [ORNL] [ORNL; Schulz, Roland [ORNL] [ORNL; Smith, Jeremy C [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    The precipitation of lignin onto cellulose after pretreatment of lignocellulosic biomass is an obstacle to economically viable cellulosic ethanol production. Here, 750 ns nonequilibrium molecular dynamics simulations are reported of a system of lignin and cellulose in aqueous solution. Lignin is found to strongly associate with itself and the cellulose. However, noncrystalline regions of cellulose are observed to have a lower tendency to associate with lignin than crystalline regions, and this is found to arise from stronger hydration of the noncrystalline chains. The results suggest that the recalcitrance of crystalline cellulose to hydrolysis arises not only from the inaccessibility of inner fibers but also due to the promotion of lignin adhesion.

  6. Use of Aria to simulate laser weld pool dynamics for neutron generator production.

    SciTech Connect (OSTI)

    Noble, David R.; Notz, Patrick K.; Martinez, Mario J.; Kraynik, Andrew Michael

    2007-09-01T23:59:59.000Z

    This report documents the results for the FY07 ASC Integrated Codes Level 2 Milestone number 2354. The description for this milestone is, 'Demonstrate level set free surface tracking capabilities in ARIA to simulate the dynamics of the formation and time evolution of a weld pool in laser welding applications for neutron generator production'. The specialized boundary conditions and material properties for the laser welding application were implemented and verified by comparison with existing, two-dimensional applications. Analyses of stationary spot welds and traveling line welds were performed and the accuracy of the three-dimensional (3D) level set algorithm is assessed by comparison with 3D moving mesh calculations.

  7. PuReMD-GPU: A reactive molecular dynamics simulation package for GPUs

    SciTech Connect (OSTI)

    Kylasa, S.B., E-mail: skylasa@purdue.edu [Department of Elec. and Comp. Eng., Purdue University, West Lafayette, IN 47907 (United States); Aktulga, H.M., E-mail: hmaktulga@lbl.gov [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, MS 50F-1650, Berkeley, CA 94720 (United States); Grama, A.Y., E-mail: ayg@cs.purdue.edu [Department of Computer Science, Purdue University, West Lafayette, IN 47907 (United States)

    2014-09-01T23:59:59.000Z

    We present an efficient and highly accurate GP-GPU implementation of our community code, PuReMD, for reactive molecular dynamics simulations using the ReaxFF force field. PuReMD and its incorporation into LAMMPS (Reax/C) is used by a large number of research groups worldwide for simulating diverse systems ranging from biomembranes to explosives (RDX) at atomistic level of detail. The sub-femtosecond time-steps associated with ReaxFF strongly motivate significant improvements to per-timestep simulation time through effective use of GPUs. This paper presents, in detail, the design and implementation of PuReMD-GPU, which enables ReaxFF simulations on GPUs, as well as various performance optimization techniques we developed to obtain high performance on state-of-the-art hardware. Comprehensive experiments on model systems (bulk water and amorphous silica) are presented to quantify the performance improvements achieved by PuReMD-GPU and to verify its accuracy. In particular, our experiments show up to 16× improvement in runtime compared to our highly optimized CPU-only single-core ReaxFF implementation. PuReMD-GPU is a unique production code, and is currently available on request from the authors.

  8. Game-based dynamic simulations supporting technical education and training iJOE International Journal of Online Engineering -www.i-joe.org 1

    E-Print Network [OSTI]

    Foss, Bjarne A.

    . SIMULATIONS AND GAMES FOR LEARNING PURPOSES The development of ICT solutions has allowed for more complex and advanced representations of learning material. In this context, dynamic simulators can be regardedGame-based dynamic simulations supporting technical education and training iJOE International

  9. Study on the thermal resistance in secondary particles chain of silica aerogel by molecular dynamics simulation

    SciTech Connect (OSTI)

    Liu, M. [Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing100190 (China); Department of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Qiu, L., E-mail: qiulin111@sina.com, E-mail: jzzhengxinghua@163.com; Zheng, X. H., E-mail: qiulin111@sina.com, E-mail: jzzhengxinghua@163.com; Zhu, J.; Tang, D. W. [Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing100190 (China)

    2014-09-07T23:59:59.000Z

    In this article, molecular dynamics simulation was performed to study the heat transport in secondary particles chain of silica aerogel. The two adjacent particles as the basic heat transport unit were modelled to characterize the heat transfer through the calculation of thermal resistance and vibrational density of states (VDOS). The total thermal resistance of two contact particles was predicted by non-equilibrium molecular dynamics simulations (NEMD). The defects were formed by deleting atoms in the system randomly first and performing heating and quenching process afterwards to achieve the DLCA (diffusive limited cluster-cluster aggregation) process. This kind of treatment showed a very reasonable prediction of thermal conductivity for the silica aerogels compared with the experimental values. The heat transport was great suppressed as the contact length increased or defect concentration increased. The constrain effect of heat transport was much significant when contact length fraction was in the small range (<0.5) or the defect concentration is in the high range (>0.5). Also, as the contact length increased, the role of joint thermal resistance played in the constraint of heat transport was increasing. However, the defect concentration did not affect the share of joint thermal resistance as the contact length did. VDOS of the system was calculated by numerical method to characterize the heat transport from atomic vibration view. The smaller contact length and greater defect concentration primarily affected the longitudinal acoustic modes, which ultimately influenced the heat transport between the adjacent particles.

  10. Simulations of the dissociation of small helium clusters with ab initio molecular dynamics in electronically excited states

    SciTech Connect (OSTI)

    Closser, Kristina D.; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu [Department of Chemistry, University of California Berkeley, Berkeley, California 94720 (United States) [Department of Chemistry, University of California Berkeley, Berkeley, California 94720 (United States); Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Gessner, Oliver [Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2014-04-07T23:59:59.000Z

    The dynamics resulting from electronic excitations of helium clusters were explored using ab initio molecular dynamics. The simulations were performed with configuration interaction singles and adiabatic classical dynamics coupled to a state-following algorithm. 100 different configurations of He{sub 7} were excited into the 2s and 2p manifold for a total of 2800 trajectories. While the most common outcome (90%) was complete fragmentation to 6 ground state atoms and 1 excited state atom, 3% of trajectories yielded bound, He {sub 2}{sup *}, and <0.5% yielded an excited helium trimer. The nature of the dynamics, kinetic energy release, and connections to experiments are discussed.

  11. Dynamic simulations of geologic materials using combined FEM/DEM/SPH analysis

    SciTech Connect (OSTI)

    Morris, J P; Johnson, S M

    2008-03-26T23:59:59.000Z

    An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geologic materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such as projectile penetration into rock, concrete targets, and boulder fields, require a combination of continuum and discrete methods in order to predict the formation and interaction of the fragments produced. In an effort to model this class of problems, LDEC now includes implementations of Cosserat point theory and cohesive elements. This approach directly simulates the transition from continuum to discontinuum behavior, thereby allowing for dynamic fracture within a combined finite element/discrete element framework. In addition, there are many application involving geologic materials where fluid-structure interaction is important. To facilitate solution of this class of problems a Smooth Particle Hydrodynamics (SPH) capability has been incorporated into LDEC to simulate fully coupled systems involving geologic materials and a saturating fluid. We will present results from a study of a broad range of geomechanical problems that exercise the various components of LDEC in isolation and in tandem.

  12. Simulation of dynamic fracture using peridynamics, finite element modeling, and contact.

    SciTech Connect (OSTI)

    Littlewood, David John

    2010-11-01T23:59:59.000Z

    Peridynamics is a nonlocal extension of classical solid mechanics that allows for the modeling of bodies in which discontinuities occur spontaneously. Because the peridynamic expression for the balance of linear momentum does not contain spatial derivatives and is instead based on an integral equation, it is well suited for modeling phenomena involving spatial discontinuities such as crack formation and fracture. In this study, both peridynamics and classical finite element analysis are applied to simulate material response under dynamic blast loading conditions. A combined approach is utilized in which the portion of the simulation modeled with peridynamics interacts with the finite element portion of the model via a contact algorithm. The peridynamic portion of the analysis utilizes an elastic-plastic constitutive model with linear hardening. The peridynamic interface to the constitutive model is based on the calculation of an approximate deformation gradient, requiring the suppression of possible zero-energy modes. The classical finite element portion of the model utilizes a Johnson-Cook constitutive model. Simulation results are validated by direct comparison to expanding tube experiments. The coupled modeling approach successfully captures material response at the surface of the tube and the emerging fracture pattern. The coupling of peridynamics and finite element analysis via a contact algorithm has been shown to be a viable means for simulating material fracture in a high-velocity impact experiment. A combined peridynamics/finite element approach was applied to model an expanding tube experiment performed by Vogler, et al., in which loading on the tube is a result of Lexan slugs impacting inside the tube. The Lexan portion of the simulation was modeled with finite elements and a Johnson-Cook elastic-plastic material model in conjunction with an equation-of-state law. The steel tube portion of the simulation was modeled with peridynamics, an elastic-plastic material model, and a critical stretch bond damage model. The application of peridynamics to the tube portion of the model allowed the capture of the formation of cracks and eventual fragmentation of the tube. The simulation results yielded good agreement with the experimental results published by Vogler, et al., for the velocity and displacement profiles on the surface of the tube and the resulting fragment distribution. Numerical difficulties were encountered that required removal of hexahedron elements from the Lexan portion of the model over the course of the simulation. The significant number of inverted and nearly-inverted elements appearing over the course of the simulation is believed to be a result of irregularities in the contact between the Lexan and AerMet portions of the model, and was likely exacerbated by the ultra-high strength of the AerMet tube. Future simulations are planned in which the Lexan portion of the simulation is modeled with peridynamics, or with an alternative method such as smoothed particle hydrodynamics, with the goal of reducing these numerical difficulties.

  13. 3.021J / 1.021J / 10.333J / 18.361J / 22.00J Introduction to Modeling and Simulation, Spring 2011

    E-Print Network [OSTI]

    Buehler, Markus

    This subject provides an introduction to modeling and simulation (IM/S), covering continuum methods, atomistic and molecular simulation (e.g. molecular dynamics) as well as quantum mechanics. These tools play an increasingly ...

  14. Abstract --The simulation of Proton Exchange Membrane Fuel Cells (PEMFC) may work as a powerful tool in the

    E-Print Network [OSTI]

    Simões, Marcelo Godoy

    the conventional sources. Among the energy sources considered, (such as wind power, photovoltaic power and small aggression to the environment, excellent dynamic response, and superior reliability and durability. Among

  15. Development Plan for the Fuel Cycle Simulator

    SciTech Connect (OSTI)

    Brent Dixon

    2011-09-01T23:59:59.000Z

    The Fuel Cycle Simulator (FCS) project was initiated late in FY-10 as the activity to develop a next generation fuel cycle dynamic analysis tool for achieving the Systems Analysis Campaign 'Grand Challenge.' This challenge, as documented in the Campaign Implementation Plan, is to: 'Develop a fuel cycle simulator as part of a suite of tools to support decision-making, communication, and education, that synthesizes and visually explains the multiple attributes of potential fuel cycles.'

  16. Development of an operational tool to simulate pesticide transfer through vegetated strips: the 2D runoff part

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    dimensions. Materiel and method This tool uses Richards and Kinematic wave equations to describe respectively tables. Kinematic wave calculations are solved in two-dimensional form, using a finite volume method the most famous test to check if a code solving the kinematic wave is robust against hard changes of slopes

  17. Deployment of a Suite of High-Performance Computational Tools for Multi-scale Multi-physics Simulation of Generation IV Reactors

    SciTech Connect (OSTI)

    Michael Z. Podowski

    2013-01-03T23:59:59.000Z

    The overall objective of this project has been to deploy advanced simulation capabilities for next generation reactor systems utilizing newly available, high-performance computing facilities. The approach includes the following major components: The development of new simulation capabilities using state-of-the-art computer codes of different scales: molecular dynamics (MD) level, DNS (FronTier and PHASTA) and CFD (NPHASE-CMFD); The development of advanced numerical solvers for large-size computational problems; The deployment of a multiple-code computational platform for multiscale simulations of gas/liquid two-phase flow during reactor transients and accidents; and Application of the new computational methodology to study the progression of loss-of-flow accident in sodium fast reactor (SFR).

  18. Simulation studies of slow dynamics of hydration water in lysozyme : hydration level dependence and comparison with experiment using new time domain analysis

    E-Print Network [OSTI]

    Kim, Chansoo, S.M. Massachusetts Institute of Technology

    2008-01-01T23:59:59.000Z

    A series of Molecular Dynamics (MD) simulations using the GROMACS® package has been performed in this thesis. It is used to mimic and simulate the hydration water in Lysozyme with three different hydration levels (h = 0.3, ...

  19. Simulation as a Tool to Develop Guidelines of Envelope Design of a Typical Office Building in Egypt

    E-Print Network [OSTI]

    Samaan, M.M.; Ahmed, A.N.; Farag, O.M.A.; El-Sayed Khalil, M.

    2011-01-01T23:59:59.000Z

    This paper describes the use of building performance simulation software in order to develop guidelines for designing energy-efficient office building. In Egypt energy codes for all building types are being under development. On the other hand...

  20. Development of EEM based silicon–water and silica–water wall potentials for non-reactive molecular dynamics simulations

    SciTech Connect (OSTI)

    Kim, Junghan; Iype, Eldhose; Frijns, Arjan J.H.; Nedea, Silvia V.; Steenhoven, Anton A. van

    2014-07-01T23:59:59.000Z

    Molecular dynamics simulations of heat transfer in gases are computationally expensive when the wall molecules are explicitly modeled. To save computational time, an implicit boundary function is often used. Steele's potential has been used in studies of fluid–solid interface for a long time. In this work, the conceptual idea of Steele's potential was extended in order to simulate water–silicon and water–silica interfaces. A new wall potential model is developed by using the electronegativity-equalization method (EEM), a ReaxFF empirical force field and a non-reactive molecular dynamics package PumMa. Contact angle simulations were performed in order to validate the wall potential model. Contact angle simulations with the resulting tabulated wall potentials gave a silicon–water contact angle of 129°, a quartz–water contact angle of 0°, and a cristobalite–water contact angle of 40°, which are in reasonable agreement with experimental values.

  1. The Melting Temperature of Bulk Silicon from ab initio Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    Yoo, Soohaeng; Xantheas, Sotiris S.; Zeng, Xiao Cheng

    2009-10-19T23:59:59.000Z

    We estimated a melting temperature of Tm ~ 1540 ± 90 K at zero pressure for silicon from constant enthalpy and constant pressure (NPH) Born-Oppenheimer Molecular Dynamics (BOMD) simulations of a coexisting crystalline-liquid phase. The computed Tm is below the experimental melting point of 1685 K, but it is consistent with a previously predicted first-order liquid-liquid phase transition (LLPT) at a critical point Tc ~ 1232 K and Pc ~ - 12kB [Ganesh and Widom, Phys. Rev. Lett. 102, 075701 (2009)], which is in a highly supercooled state. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Chemical Sciences program. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  2. Solvent Electrostriction Driven Peptide Folding revealed by Quasi-Gaussian Entropy Theory and Molecular Dynamics Simulation

    SciTech Connect (OSTI)

    Noe, F [University of Heidelberg; Daidone, Isabella [University of Heidelberg; Smith, Jeremy C [ORNL; DiNola, Alfredo [University of Rome; Amadei, Andrea [University of Rome 'Tor Vergata', Rome, Italy

    2008-06-01T23:59:59.000Z

    A quantitative understanding of the complex relationship between microscopic structure and the thermodynamics driving peptide and protein folding is a major goal of biophysical chemistry. Here, we present a methodology comprising the use of an extended quasi-Gaussian entropy theory parametrized using molecular dynamics simulation that provides a complete description of the thermodynamics of peptide conformational states. The strategy is applied to analyze the conformational thermodynamics of MR121-GSGSW, a peptide well characterized in experimental studies. The results demonstrate that the extended state of the peptide possesses the lowest partial molar entropy. The origin of this entropy decrease is found to be in the increase of the density and orientational order of the hydration water molecules around the peptide, induced by the 'unfolding'. While such a reduction of the configurational entropy is usually associated with the hydrophobic effect, it is here found to be mainly due to the interaction of the solute charges with the solvent, that is, electrostriction.

  3. Solvent Electrostriction-Driven Peptide Folding Revealed by Quasi Gaussian Entropy Theory and Molecular Dynamics Simulation

    SciTech Connect (OSTI)

    Noe, F [University of Heidelberg; Daidone, Isabella [University of Heidelberg; Smith, Jeremy C [ORNL; DiNola, Alfredo [University of Rome; Amadei, Andrea [University of Rome 'Tor Vergata', Rome, Italy

    2008-08-01T23:59:59.000Z

    A quantitative understanding of the complex relationship between microscopic structure and the thermodynamics driving peptide and protein folding is a major goal of biophysical chemistry. Here, we present a methodology comprising the use of an extended quasi-Gaussian entropy theory parametrized using molecular dynamics simulation that provides a complete description of the thermodynamics of peptide conformational states. The strategy is applied to analyze the conformational thermodynamics of MR121-GSGSW, a peptide well characterized in experimental studies. The results demonstrate that the extended state of the peptide possesses the lowest partial molar entropy. The origin of this entropy decrease is found to be in the increase of the density and orientational order of the hydration water molecules around the peptide, induced by the 'unfolding'. While such a reduction of the configurational entropy is usually associated with the hydrophobic effect, it is here found to be mainly due to the interaction of the solute charges with the solvent, that is, electrostriction.

  4. Molecular dynamics simulations of oscillatory Couette flows with slip boundary conditions

    E-Print Network [OSTI]

    Nikolai V. Priezjev

    2012-08-27T23:59:59.000Z

    The effect of interfacial slip on steady-state and time-periodic flows of monatomic liquids is investigated using non-equilibrium molecular dynamics simulations. The fluid phase is confined between atomically smooth rigid walls, and the fluid flows are induced by moving one of the walls. In steady shear flows, the slip length increases almost linearly with shear rate. We found that the velocity profiles in oscillatory flows are well described by the Stokes flow solution with the slip length that depends on the local shear rate. Interestingly, the rate dependence of the slip length obtained in steady shear flows is recovered when the slip length in oscillatory flows is plotted as a function of the local shear rate magnitude. For both types of flows, the friction coefficient at the liquid-solid interface correlates well with the structure of the first fluid layer near the solid wall.

  5. Polymer segregation under confinement: Free energy calculations and segregation dynamics simulations

    E-Print Network [OSTI]

    James M. Polson; Logan G. Montgomery

    2014-10-09T23:59:59.000Z

    Monte Carlo simulations are used to study the behavior of two polymers under confinement in a cylindrical tube. Each polymer is modeled as a chain of hard spheres. We measure the free energy of the system, F, as a function of the distance between the centers of mass of the polymers, lambda, and examine the effects on the free energy functions of varying the channel diameter D and length L, as well as the polymer length N and bending rigidity, kappa. For infinitely long cylinders, F is a maximum at lambda=0, and decreases with lambda until the polymers are no longer in contact. For flexible chains, the polymers overlap along the cylinder for low lambda, while above some critical value of lambda they are longitudinally compressed and non-overlapping while still in contact. We find that the free energy barrier height, scales as Delta F/k_BT~ND^{-1.93+/-0.01}. In addition, the overlap free energy scales as F/k_BT=Nf(lambda/N;D), where f is a function parameterized by D. For channels of finite L, the free energy barrier height increases with increasing confinement aspect ratio L/D at fixed volume fraction phi, and it decreases with increasing phi at fixed L/D. Increasing the polymer bending rigidity kappa monotonically reduces the overlap free energy. For strongly confined systems, F varies linearly with lambda with a slope that scales as F'(lambda)~-k_BT D^{-beta} P^{-alpha}, where beta approx 2 and alpha approx 0.37 for N=200 chains. These exponent values deviate slightly from those predicted using a simple model, possibly due to insufficiently satisfying the conditions defining the Odijk regime. Finally, we use Monte Carlo dynamics simulations to examine polymer segregation dynamics for fully flexible chains and observe segregation rates that decrease with decreasing entropic force magnitude. The polymers are not conformationally relaxed at later times during segregation.

  6. Plant-wide dynamic simulation of an IGCC plant with CO2 capture

    SciTech Connect (OSTI)

    Bhattacharyya, D.; Turton, R.; Zitney, S.

    2009-01-01T23:59:59.000Z

    To eliminate the harmful effects of greenhouse gases, especially that of CO2, future coalfired power plants need to consider the option for CO2 capture. The loss in efficiency for CO2 capture is less in an Integrated Gasification Combined Cycle (IGCC) plant compared to other conventional coal combustion processes. However, no IGCC plant with CO2 capture currently exists in the world. Therefore, it is important to consider the operability and controllability issues of such a plant before it is commercially built. With this objective in mind, a detailed plant-wide dynamic simulation of an IGCC plant with CO2 capture has been developed. The plant considers a General Electric Energy (GEE)-type downflow radiant-only gasifier followed by a quench section. A two-stage water gas shift (WGS) reaction is considered for conversion of about 96 mol% of CO to CO2. A two-stage acid gas removal (AGR) process based on a physical solvent is simulated for selective capture of H2S and CO2. The clean syngas is sent to a gas turbine (GT) followed by a heat recovery steam generator (HRSG). The steady state results are validated with data from a commercial gasifier. A 5 % ramp increase in the flowrate of coal is introduced to study the system dynamics. To control the conversion of CO at a desired level in the WGS reactors, the steam/CO ratio is manipulated. This strategy is found to be efficient for this operating condition. In the absence of an efficient control strategy in the AGR process, the environmental emissions exceeded the limits by a great extent.

  7. 15.872 System Dynamics II, Fall 2010

    E-Print Network [OSTI]

    Sterman, John

    15.872 is a continuation of 15.871 Introduction to System Dynamics. It emphasizes tools and methods needed to apply systems thinking and simulation modeling successfully in complex real-world settings. The course uses ...

  8. Statechart Simulator for Modeling Architectural Dynamics1 Alexander Egyed Dave Wile

    E-Print Network [OSTI]

    Egyed, Alexander

    support for simulation. For instance, Darwin/LTSA [10,11] provides a simulator for executing labeled

  9. Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions

    SciTech Connect (OSTI)

    Oberhofer, Harald; Blumberger, Jochen [Department of Chemistry, University of Cambridge, Cambridge CB2 1EW (United Kingdom)

    2009-08-14T23:59:59.000Z

    We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following the earlier work of Wu and Van Voorhis [Phys. Rev. A 72, 024502 (2005)], the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge and present expressions for the constraint forces. The method is applied to the Ru{sup 2+}-Ru{sup 3+} electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. The smaller value for the reorganization free energy can be explained by the fact that the Ru-O distances of the divalent and trivalent Ru hexahydrates are predicted to be more similar in the electron transfer complex than for the separated aqua ions.

  10. Molecular Dynamics Simulation of Cascade-Induced Ballistic Helium Resolutioning from Bubbles in Iron

    SciTech Connect (OSTI)

    Stoller, Roger E [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    Molecular dynamics simulations have been used to assess the ability of atomic displacement cascades to eject helium from small bubbles in iron. This study of the ballistic resolutioning mechanism employed a recently-developed Fe-He interatomic potential in concert with an iron potential developed by Ackland and co-workers. The primary variables examined were: irradiation temperature (100 and 600K), cascade energy (5 and 20 keV), bubble radius (0.5 and 1.0 nm), and He-to-vacancy ratio in the bubble (0.25, 0.5 and 1.0). Systematic trends were observed for each of these variables. For example, ballistic resolutioning leads to a greater number of helium atoms being displaced from larger bubbles and from bubbles that have a higher He/vacancy ratio (bubble pressure). He resolutioning was reduced at 600K relative to 100K, and for 20 keV cascades relative to 5 keV cascades. Overall, the results indicate a modest level of He removal by ballistic resolutioning. The results can be used to provide guidance in selection of a resolution parameter that can be employed in cluster dynamics models to predict the bubble size distribution that evolves under irradiation.

  11. Experiment and Simulation of Dynamic Voltage Regulation in Multiple Distributed Energy Resources Systems

    SciTech Connect (OSTI)

    Xu, Yan [ORNL; Li, Fangxing [ORNL; Kueck, John D [ORNL; Rizy, D Tom [ORNL

    2007-01-01T23:59:59.000Z

    Distributed energy (DE) resources are power sources located near load centers and equipped with power electronics converters to interface with the grid, therefore it is feasible for DE to provide reactive power (along with active power) locally for dynamic voltage regulation. In this paper, a synchronous condenser and a microturbine with an inverter interface are implemented in parallel in a distribution system to regulate the local voltage. Developed voltage control schemes for the inverter and the synchronous condenser are presented. Experimental results show that both the inverter and the synchronous condenser can regulate the local voltage instantaneously although the dynamic response of the inverter is much faster than the synchronous condenser. In a system with multiple DEs performing local voltage regulation, the interaction between the DEs is studied. The simulation results show the relationship between the voltages in the system and the reactive power required for the voltage regulation. Also, integrated voltage regulation (multiple DEs performing voltage regulation) can increase the voltage regulation capability of DEs and reduce the capital and operating costs.

  12. The use of dynamic adaptive chemistry in combustion simulation of gasoline surrogate fuels

    SciTech Connect (OSTI)

    Liang, Long; Raman, Sumathy; Farrell, John T. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Stevens, John G. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Department of Mathematical Sciences, Montclair State University, Montclair, NJ 07043 (United States)

    2009-07-15T23:59:59.000Z

    A computationally efficient dynamic adaptive chemistry (DAC) scheme is described that permits on-the-fly mechanism reduction during reactive flow calculations. The scheme reduces a globally valid full mechanism to a locally, instantaneously applicable smaller mechanism. Previously we demonstrated its applicability to homogeneous charge compression ignition (HCCI) problems with n-heptane [L. Liang, J.G. Stevens, J.T. Farrell, Proc. Combust. Inst. 32 (2009) 527-534]. In this work we demonstrate the broader utility of the DAC scheme through the simulation of HCCI and shock tube ignition delay times (IDT) for three gasoline surrogates, including two- and three-component blends of primary reference fuels (PRF) and toluene reference fuels (TRF). Both a detailed 1099-species mechanism and a skeletal 150-species mechanism are investigated as the full mechanism to explore the impact of fuel complexity on the DAC scheme. For all conditions studied, pressure and key species profiles calculated using the DAC scheme are in excellent agreement with the results obtained using the full mechanisms. For the HCCI calculations using the 1099- and 150-species mechanisms, the DAC scheme achieves 70- and 15-fold CPU time reductions, respectively. For the IDT problems, corresponding speed-up factors of 10 and two are obtained. Practical guidance is provided for choosing the search-initiating species set, selecting the threshold, and implementing the DAC scheme in a computational fluid dynamics (CFD) framework. (author)

  13. Molecular dynamics simulation of shock induced ejection on fused silica surface

    SciTech Connect (OSTI)

    Su, Rui [College of Physical Science and Technology, Sichuan University, Chengdu 610064 (China); Xiang, Meizhen; Jiang, Shengli [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Chen, Jun, E-mail: jun-chen@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Center for Applied Physics and Technology, Peking University, Beijing 100087 (China); Wei, Han [Research Center of Laser Fusion, Mianyang 621900 (China)

    2014-05-21T23:59:59.000Z

    Shock response and surface ejection behaviors of fused silica are studied by using non-equilibrium molecular dynamics combining with the Tersoff potential. First, bulk structure and Hugoniot curves of fused silica are calculated and compared with experimental results. Then, the dynamical process of surface ejection behavior is simulated under different loading velocities ranging from 3.5 to 5.0?km?s, corresponding to shock wave velocities from 7.1 to 8.8?km?s. The local atomistic shear strain parameter is used to describe the local plastic deformation under conditions of shock compression or releasing. Our result shows that the shear strain is localized in the bottom area of groove under the shock compression. Surface ejection is observed when the loading velocity exceeds 4.0?km?s. Meanwhile, the temperature of the micro-jet is ?5574.7?K, which is close to experiment measurement. Several kinds of structural defects including non-bridging oxygen are found in the bulk area of the sample after ejection.

  14. Dynamic Simulation of Shipping Package Subjected to Torque Load and Sequential Impacts

    SciTech Connect (OSTI)

    Wu, T

    2006-04-17T23:59:59.000Z

    A numerical technique has been developed to simulate the structural responses of radioactive material packaging components requiring closure-tightening torque to the scenarios of the hypothetical accident conditions (HAC) defined in the Code of Federal Regulations Title 10 part 71 (10CFR 71). A rigorous solution to this type of problem poses a considerable mathematical challenge. Conventional methods for evaluating the residue stresses due to the torque load are either inaccurate or not applicable to dynamic analyses. In addition, the HAC events occur sequentially and the cumulative damage to the package needs to be evaluated. Commonly, individual HAC events are analyzed separately and the cumulative damage is not addressed. As a result, strict compliance of the package with the requirements specified in 10CFR 71 is usually demonstrated by physical testing. The proposed technique utilizes the combination of kinematic constraints, rigid-body motions and structural deformations to overcome some of the difficulties encountered in modeling the effect of cumulative damage in numerical solutions. The analyses demonstrating use of this technique were performed to determine the cumulative damage of torque preload, a 30-foot drop, a 30-foot dynamic crush and a 40-inch free fall onto a mild steel pipe.

  15. Properties of liquid clusters in large-scale molecular dynamics nucleation simulations

    SciTech Connect (OSTI)

    Angélil, Raymond; Diemand, Jürg [Institute for Theoretical Physics, University of Zurich, 8057 Zurich (Switzerland)] [Institute for Theoretical Physics, University of Zurich, 8057 Zurich (Switzerland); Tanaka, Kyoko K.; Tanaka, Hidekazu [Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819 (Japan)] [Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819 (Japan)

    2014-02-21T23:59:59.000Z

    We have performed large-scale Lennard-Jones molecular dynamics simulations of homogeneous vapor-to-liquid nucleation, with 10{sup 9} atoms. This large number allows us to resolve extremely low nucleation rates, and also provides excellent statistics for cluster properties over a wide range of cluster sizes. The nucleation rates, cluster growth rates, and size distributions are presented in Diemand et al. [J. Chem. Phys. 139, 74309 (2013)], while this paper analyses the properties of the clusters. We explore the cluster temperatures, density profiles, potential energies, and shapes. A thorough understanding of the properties of the clusters is crucial to the formulation of nucleation models. Significant latent heat is retained by stable clusters, by as much as ?kT = 0.1? for clusters with size i = 100. We find that the clusters deviate remarkably from spherical—with ellipsoidal axis ratios for critical cluster sizes typically within b/c = 0.7 ± 0.05 and a/c = 0.5 ± 0.05. We examine cluster spin angular momentum, and find that it plays a negligible role in the cluster dynamics. The interfaces of large, stable clusters are thinner than planar equilibrium interfaces by 10%?30%. At the critical cluster size, the cluster central densities are between 5% and 30% lower than the bulk liquid expectations. These lower densities imply larger-than-expected surface areas, which increase the energy cost to form a surface, which lowers nucleation rates.

  16. Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

    E-Print Network [OSTI]

    Andrade, Xavier; De Giovannini, Umberto; Larsen, Ask Hjorth; Oliveira, Micael J T; Alberdi-Rodriguez, Joseba; Varas, Alejandro; Theophilou, Iris; Helbig, Nicole; Verstraete, Matthieu; Stella, Lorenzo; Nogueira, Fernando; Aspuru-Guzik, Alán; Castro, Alberto; Marques, Miguel A L; Rubio, Ángel

    2015-01-01T23:59:59.000Z

    Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schr\\"odinger equation for low-dimensionality systems.

  17. Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

    SciTech Connect (OSTI)

    Chang, Ho-Myung; Park, Chan Woo [Hong Ik University, Department of Mechanical Engineering, Seoul, 121-791 (Korea, Republic of); Yang, Hyung Suk; Hwang, Si Dole [KEPCO Research Institute, Daejeon, 305-760 (Korea, Republic of)

    2014-01-29T23:59:59.000Z

    Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1?3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

  18. Ratcheted molecular-dynamics simulations identify efficiently the transition state of protein folding

    E-Print Network [OSTI]

    Guido Tiana; Carlo Camilloni

    2012-07-05T23:59:59.000Z

    The atomistic characterization of the transition state is a fundamental step to improve the understanding of the folding mechanism and the function of proteins. From a computational point of view, the identification of the conformations that build out the transition state is particularly cumbersome, mainly because of the large computational cost of generating a statistically-sound set of folding trajectories. Here we show that a biasing algorithm, based on the physics of the ratchet-and-pawl, can be used to identify efficiently the transition state. The basic idea is that the algorithmic ratchet exerts a force on the protein when it is climbing the free-energy barrier, while it is inactive when it is descending. The transition state can be identified as the point of the trajectory where the ratchet changes regime. Besides discussing this strategy in general terms, we test it within a protein model whose transition state can be studied independently by plain molecular dynamics simulations. Finally, we show its power in explicit-solvent simulations, obtaining and characterizing a set of transition--state conformations for ACBP and CI2.

  19. Molecular Dynamics Simulations of Uranyl and Uranyl Carbonate Adsorption at Alumino-silicate Surfaces

    SciTech Connect (OSTI)

    Kerisit, Sebastien N.; Liu, Chongxuan

    2014-03-03T23:59:59.000Z

    Adsorption at mineral surfaces is a critical factor controlling the mobility of uranium(VI) in aqueous environments. Therefore, molecular dynamics (MD) simulations were performed to investigate uranyl(VI) adsorption onto two neutral alumino-silicate surfaces, namely the orthoclase (001) surface and the octahedral aluminum sheet of the kaolinite (001) surface. Although uranyl preferentially adsorbed as a bi-dentate innersphere complex on both surfaces, the free energy of adsorption at the orthoclase surface (-15 kcal mol-1) was significantly more favorable than that at the kaolinite surface (-3 kcal mol-1), which was attributed to differences in surface functional groups and to the ability of the orthoclase surface to dissolve a surface potassium ion upon uranyl adsorption. The structures of the adsorbed complexes compared favorably with X-ray absorption spectroscopy results. Simulations of the adsorption of uranyl complexes with up to three carbonate ligands revealed that uranyl complexes coordinated to up to 2 carbonate ions are stable on the orthoclase surface whereas uranyl carbonate surface complexes are unfavored at the kaolinite surface. Combining the MD-derived equilibrium adsorption constants for orthoclase with aqueous equilibrium constants for uranyl carbonate species indicates the presence of adsorbed uranium complexes with one or two carbonates in alkaline conditions, in support of current uranium(VI) surface complexation models.

  20. BEAM DYNAMICS SIMULATIONS OF SARAF ACCELERATOR INCLUDING ERROR PROPAGATION AND IMPLICATIONS FOR THE EURISOL DRIVER

    E-Print Network [OSTI]

    J. Rodnizki, D. Berkovits, K. Lavie, I. Mardor, A. Shor and Y. Yanay (Soreq NRC, Yavne), K. Dunkel, C. Piel (ACCEL, Bergisch Gladbach), A. Facco (INFN/LNL, Legnaro, Padova), V. Zviagintsev (TRIUMF, Vancouver)

    AbstractBeam dynamics simulations of SARAF (Soreq Applied Research Accelerator Facility) superconducting RF linear accelerator have been performed in order to establish the accelerator design. The multi-particle simulation includes 3D realistic electromagnetic field distributions, space charge forces and fabrication, misalignment and operation errors. A 4 mA proton or deuteron beam is accelerated up to 40 MeV with a moderated rms emittance growth and a high real-estate gradient of 2 MeV/m. An envelope of 40,000 macro-particles is kept under a radius of 1.1 cm, well below the beam pipe bore radius. The accelerator design of SARAF is proposed as an injector for the EURISOL driver accelerator. The Accel 176 MHZ ?0=0.09 and ?0=0.15 HWR lattice was extended to 90 MeV based on the LNL 352 MHZ ?0=0.31 HWR. The matching between both lattices ensures smooth transition and the possibility to extend the accelerator to the required EURISOL ion energy.

  1. Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates

    SciTech Connect (OSTI)

    Guseva, D. V., E-mail: d.v.guseva@tue.nl [Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven (Netherlands); Physics Department, Chair of Polymer and Crystal Physics, M. V. Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Komarov, P. V. [Department of Theoretical Physics, Tver State University, Sadovyj per. 35, 170002 Tver, Russia and Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova st. 28, 119991 Moscow (Russian Federation)] [Department of Theoretical Physics, Tver State University, Sadovyj per. 35, 170002 Tver, Russia and Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova st. 28, 119991 Moscow (Russian Federation); Lyulin, Alexey V. [Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven (Netherlands)] [Theory of Polymers and Soft Matter, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB, Eindhoven (Netherlands)

    2014-03-21T23:59:59.000Z

    Constant temperature–constant pressure (NpT) molecular-dynamics computer simulations have been carried out for the united-atom model of a non-crosslinked (1,4) cis-polyisoprene (PI) melt confined between two amorphous, fully coordinated silica surfaces. The Lennard-Jones 12-6 potential was implemented to describe the polymer–silica interactions. The thickness H of the produced PI–silica film has been varied in a wide range, 1 < H/R{sub g} < 8, where R{sub g} is the individual PI chain radius of gyration measured under the imposed confinement. After a thorough equilibration, the PI film stratified structure and polymer segmental dynamics have been studied. The chain structure in the middle of the films resembles that in a corresponding bulk, but the polymer-density profile shows a pronounced ordering of the polymer segments in the vicinity of silica surfaces; this ordering disappears toward the film middles. Tremendous slowing down of the polymer segmental dynamics has been observed in the film surface layers, with the segmental relaxation more than 150 times slower as compared to that in a PI bulk. This effect increases with decreasing the polymer-film thickness. The segmental relaxation in the PI film middles shows additional relaxation process which is absent in a PI bulk. Even though there are fast relaxation processes in the film middle, its overall relaxation is slower as compared to that in a bulk sample. The interpretation of the results in terms of polymer glassy bridges has been discussed.

  2. AVESTAR Center: Dynamic simulation-based collaboration toward achieving opertional excellence for IGCC plants with crbon capture

    SciTech Connect (OSTI)

    Zitney, Strphen E. [U.S. DOE; Liese, Eric A. [U.S. DOE; Mahapatra, Priyadarshi [URS; Turton, Richard [WVU; Bhattacharyya, Debangsu [WVU; Provost, Graham [Fossil Consulting Services

    2012-01-01T23:59:59.000Z

    To address challenges in attaining operational excellence for clean energy plants, the National Energy Technology Laboratory has launched a world-class facility for Advanced Virtual Energy Simulation Training And Research (AVESTAR(TM)). The AVESTAR Center brings together state-of-the-art, real-time, high-fidelity dynamic simulators with operator training systems and 3D virtual immersive training systems into an integrated energy plant and control room environment. This paper will highlight the AVESTAR Center simulators, facilities, and comprehensive training, education, and research programs focused on the operation and control of an integrated gasification combined cycle power plant (IGCC) with carbon dioxide capture.

  3. Development and simulation of a cylindrical cusped-field thruster and a diagnostics tool for plasma-materials interactions

    E-Print Network [OSTI]

    Pang, Anthony

    2013-01-01T23:59:59.000Z

    A low power, Hall-effect type plasma thruster known as the MIT-Cylindrical Cusped- Field Thruster (MIT-CCFT) has been developed and simulated using a fully-kinetic plasma model, the Plasma Thruster particle-in-cell (PTpic) ...

  4. New capability will help accelerate design improvements by providing a high-fidelity simulation tool to study power

    E-Print Network [OSTI]

    New capability will help accelerate design improvements by providing a high-fidelity simulation augmentation and use of the combined LES-hydroelastic code will help accelerate the development of effective, efficient, and reliable hydrokinetic energy conversion technologies, thus helping to lower the cost

  5. Molecular Dynamics Simulation of Heat Transfer Issues of Nanotubes. > Yasuhiro Igarashi, Yuki Taniguchi, Yasushi Shibuta and Shigeo Maruyama

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Molecular Dynamics Simulation of Heat Transfer Issues of Nanotubes. ·> Yasuhiro Igarashi, Yuki 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Heat transfer between single-walled carbon nanotubes, which was 0.105 µm. In other words, when the length of SWNT is 0.105 µm, the radial heat transfer

  6. Simulation of shock-induced melting of Ni using molecular dynamics coupled to a two-temperature model

    E-Print Network [OSTI]

    Zhigilei, Leonid V.

    Department, University of Uppsala, Box 530, SE-751 21 Uppsala, Sweden 2Lawrence Livermore National Laboratory, Livermore, California 94550, USA 3National Centre for Laser Applications, Galway, Ireland 4Department at the National Ignition Facility NIF . Molecular dynamics MD simulations have been success- fully employed

  7. Solvation of Magnesium Dication: Molecular Dynamics Simulation and Vibrational Spectroscopic Study of Magnesium Chloride in Aqueous Solutions

    E-Print Network [OSTI]

    Solvation of Magnesium Dication: Molecular Dynamics Simulation and Vibrational Spectroscopic Study of Magnesium Chloride in Aqueous Solutions Karen M. Callahan, Nadia N. Casillas-Ituarte, Martina Roeselova 26, 2010 Magnesium dication plays many significant roles in biochemistry. While it is available

  8. Structural relaxation of polydisperse hard spheres: comparison of the mode-coupling theory to a Langevin dynamics simulation

    E-Print Network [OSTI]

    F. Weysser; A. M. Puertas; M. Fuchs; Th. Voigtmann

    2010-10-15T23:59:59.000Z

    We analyze the slow, glassy structural relaxation as measured through collective and tagged-particle density correlation functions obtained from Brownian dynamics simulations for a polydisperse system of quasi-hard spheres in the framework of the mode-coupling theory of the glass transition (MCT). Asymptotic analyses show good agreement for the collective dynamics when polydispersity effects are taken into account in a multi-component calculation, but qualitative disagreement at small $q$ when the system is treated as effectively monodisperse. The origin of the different small-$q$ behaviour is attributed to the interplay between interdiffusion processes and structural relaxation. Numerical solutions of the MCT equations are obtained taking properly binned partial static structure factors from the simulations as input. Accounting for a shift in the critical density, the collective density correlation functions are well described by the theory at all densities investigated in the simulations, with quantitative agreement best around the maxima of the static structure factor, and worst around its minima. A parameter-free comparison of the tagged-particle dynamics however reveals large quantiative errors for small wave numbers that are connected to the well-known decoupling of self-diffusion from structural relaxation and to dynamical heterogeneities. While deviations from MCT behaviour are clearly seen in the tagged-particle quantities for densities close to and on the liquid side of the MCT glass transition, no such deviations are seen in the collective dynamics.

  9. Incremental Integration Tools for Chemical Engineering: An Industrial Application of Triple Graph

    E-Print Network [OSTI]

    Westfechtel, Bernhard

    and the components of the chemical plant, simulation models for steady-state and dynamic simulations, etc. Design representations of a chemical plant have to be kept consistent with each other. Incremental integration tools). In chemical engineering design, a chemical plant is described from different per- spectives by a set

  10. Computational Tools to Accelerate Commercial Development

    SciTech Connect (OSTI)

    Miller, David C.

    2013-01-01T23:59:59.000Z

    The goals of the work reported are: to develop new computational tools and models to enable industry to more rapidly develop and deploy new advanced energy technologies; to demonstrate the capabilities of the CCSI Toolset on non-proprietary case studies; and to deploy the CCSI Toolset to industry. Challenges of simulating carbon capture (and other) processes include: dealing with multiple scales (particle, device, and whole process scales); integration across scales; verification, validation, and uncertainty; and decision support. The tools cover: risk analysis and decision making; validated, high-fidelity CFD; high-resolution filtered sub-models; process design and optimization tools; advanced process control and dynamics; process models; basic data sub-models; and cross-cutting integration tools.

  11. Brittle dynamic fracture of crystalline cubic silicon carbide ,,3C-SiC... via molecular dynamics simulation

    E-Print Network [OSTI]

    Southern California, University of

    Brittle dynamic fracture of crystalline cubic silicon carbide ,,3C-SiC... via molecular dynamics for three low-index crack surfaces, i.e., 110 , 111 , and 100 , in crystalline cubic silicon carbide 3C Institute of Physics. DOI: 10.1063/1.2135896 I. INTRODUCTION Potential applications of silicon carbide Si

  12. Final technical report [ACCELERATED MOLECULAR DYNAMICS SIMULATIONS OF REACTIVE HYDROCARBON SYSTEMS

    SciTech Connect (OSTI)

    Stuart, Steven J.

    2014-02-25T23:59:59.000Z

    The research activities in this project consisted of four different sub-projects. Three different accelerated dynamics techniques (parallel replica dynamics, hyperdynamics, and temperature-accelerated dynamics) were applied to the modeling of pyrolysis of hydrocarbons. In addition, parallel replica dynamics was applied to modeling of polymerization.

  13. Calculation of unsteady turbulent flow around obstacles using the large eddy simulation turbulence model

    E-Print Network [OSTI]

    Helton, Donald McLean

    2002-01-01T23:59:59.000Z

    The premise of the work presented here is to use a common analytical tool, Computational Fluid Dynamics (CFD), along with a prevalent turbulence model, Large Eddy Simulation (LES), to study the flow past rectangular cylinders. In an attempt to use...

  14. Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

    SciTech Connect (OSTI)

    Zhang, Wenjin; Peng, Yufeng [College of Physics and electronic Engineering, Henan Normal University, Xinxiang, 453007 (China)] [College of Physics and electronic Engineering, Henan Normal University, Xinxiang, 453007 (China); Liu, Zhongli, E-mail: zhongliliu@yeah.net [College of Physics and Electric Information, Luoyang Normal University, Luoyang, 471002 (China)] [College of Physics and Electric Information, Luoyang Normal University, Luoyang, 471002 (China)

    2014-05-15T23:59:59.000Z

    The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fitting the well-known Simon equation to our melting data, we yielded the melting curves for NiAl: 1783(1 + P/9.801){sup 0.298} (one-phase approach), 1850(1 + P/12.806){sup 0.357} (two-phase approach). The good agreement of the resulting equation of states and the zero-pressure melting point (calc., 1850 ± 25 K, exp., 1911 K) with experiment proved the correctness of these results. These melting data complemented the absence of experimental high-pressure melting of NiAl. To check the transferability of this EAM potential, we have also predicted the melting curves of pure nickel and pure aluminum. Results show the calculated melting point of Nickel agrees well with experiment at zero pressure, while the melting point of aluminum is slightly higher than experiment.

  15. Use of a dynamic simulation model to understand nitrogen cycling in the middle Rio Grande, NM.

    SciTech Connect (OSTI)

    Meixner, Tom (University of Arizona, Tucson, AZ); Tidwell, Vincent Carroll; Oelsner, Gretchen (University of Arizona, Tucson, AZ); Brooks, Paul (University of Arizona, Tucson, AZ); Roach, Jesse D.

    2008-08-01T23:59:59.000Z

    Water quality often limits the potential uses of scarce water resources in semiarid and arid regions. To best manage water quality one must understand the sources and sinks of both solutes and water to the river system. Nutrient concentration patterns can identify source and sink locations, but cannot always determine biotic processes that affect nutrient concentrations. Modeling tools can provide insight into these large-scale processes. To address questions about large-scale nitrogen removal in the Middle Rio Grande, NM, we created a system dynamics nitrate model using an existing integrated surface water--groundwater model of the region to evaluate our conceptual models of uptake and denitrification as potential nitrate removal mechanisms. We modeled denitrification in groundwater as a first-order process dependent only on concentration and used a 5% denitrification rate. Uptake was assumed to be proportional to transpiration and was modeled as a percentage of the evapotranspiration calculated within the model multiplied by the nitrate concentration in the water being transpired. We modeled riparian uptake as 90% and agricultural uptake as 50% of the respective evapotranspiration rates. Using these removal rates, our model results suggest that riparian uptake, agricultural uptake and denitrification in groundwater are all needed to produce the observed nitrate concentrations in the groundwater, conveyance channels, and river as well as the seasonal concentration patterns. The model results indicate that a total of 497 metric tons of nitrate-N are removed from the Middle Rio Grande annually. Where river nitrate concentrations are low and there are no large nitrate sources, nitrate behaves nearly conservatively and riparian and agricultural uptake are the most important removal mechanisms. Downstream of a large wastewater nitrate source, denitrification and agricultural uptake were responsible for approximately 90% of the nitrogen removal.

  16. Molecular dynamics simulation study of the high frequency sound waves in the fragile glass former ortho-terphenyl

    E-Print Network [OSTI]

    S. Mossa; G. Monaco; G. Ruocco; M. Sampoli; F. Sette

    2001-04-07T23:59:59.000Z

    Using a realistic flexible molecule model of the fragile glass former orthoterphenyl, we calculate via molecular dynamics simulation the collective dynamic structure factor, recently measured in this system by Inelastic X-ray Scattering. The comparison of the simulated and measured dynamic structure factor, and the study of its properties in an extended momentum, frequency and temperature range allows: i) to conclude that the utilized molecular model gives rise to a dynamic structure factor in agreement with the experimental data, for those thermodynamic states and momentum values where the latter are available; ii) to confirm the existence of a slope discontinuity on the T-dependence of the sound velocity that, at finite Q, takes place at a temperature T_x higher than the calorimetric glass transition temperature T_g; iii) to find that the values of T_x is Q-dependent and that its vanishing Q limit is consistent with T_g. The latter finding is interpreted within the framework of the current description of the dynamics of supercooled liquids in terms of exploration of the potential energy landscape.

  17. A comparative study of Lotka-Volterra and system dynamics models for simulation of technology industry dynamics

    E-Print Network [OSTI]

    Ünver, Hakk? Özgür

    2008-01-01T23:59:59.000Z

    Scholars have developed a range of qualitative and quantitative models for generalizing the dynamics of technological innovation and identifying patterns of competition between rivals. This thesis compares two predominant ...

  18. The influence of surface properties on the plasma dynamics in radio-frequency driven oxygen plasmas: Measurements and simulations

    SciTech Connect (OSTI)

    Greb, Arthur; Niemi, Kari; O'Connell, Deborah; Gans, Timo [York Plasma Institute, Department of Physics, University of York, York, YO10 5DD (United Kingdom)] [York Plasma Institute, Department of Physics, University of York, York, YO10 5DD (United Kingdom)

    2013-12-09T23:59:59.000Z

    Plasma parameters and dynamics in capacitively coupled oxygen plasmas are investigated for different surface conditions. Metastable species concentration, electronegativity, spatial distribution of particle densities as well as the ionization dynamics are significantly influenced by the surface loss probability of metastable singlet delta oxygen (SDO). Simulated surface conditions are compared to experiments in the plasma-surface interface region using phase resolved optical emission spectroscopy. It is demonstrated how in-situ measurements of excitation features can be used to determine SDO surface loss probabilities for different surface materials.

  19. A Robust Four-Fluid Transient Flow Simulator as an Analysis and Decision Making Tool for Dynamic Kill Operation

    E-Print Network [OSTI]

    Haghshenas, Arash

    2013-04-24T23:59:59.000Z

    The worst scenario of drilling operation is blowout which is uncontrolled flow of formation fluid into the wellbore. Blowouts result in environmental damage with potential risk of injuries and fatalities. Although not all blowouts result in disaster...

  20. An Occupant-Based Dynamic Simulation Tool for Predicting Residential Power Demand and Quantifying the Impact of Residential Demand Response.

    E-Print Network [OSTI]

    Johnson, Brandon Jeffrey

    2013-01-01T23:59:59.000Z

    ?? With their large impact on the power system and widespread distribution, residential loads provide vast resources that if utilized correctly have the potential to… (more)

  1. Does fluoride disrupt hydrogen bond network in cationic lipid bilayer? Time-dependent fluorescence shift of Laurdan and molecular dynamics simulations

    SciTech Connect (OSTI)

    Pokorna, Sarka; Jurkiewicz, Piotr; Hof, Martin, E-mail: martin.hof@jh-inst.cas.cz [J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Dolejskova 3, 18223 Prague 8 (Czech Republic); Vazdar, Mario [Division of Organic Chemistry and Biochemistry, Rudjer Boškovi? Institute, P.O.B. 180, HR-10002 Zagreb (Croatia); Cwiklik, Lukasz [J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic v.v.i., Dolejskova 3, 18223 Prague 8 (Czech Republic); Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6 (Czech Republic); Jungwirth, Pavel [Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6 (Czech Republic); Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland)

    2014-12-14T23:59:59.000Z

    Time-dependent fluorescence shift (TDFS) of Laurdan embedded in phospholipid bilayers reports on hydration and mobility of the phospholipid acylgroups. Exchange of H{sub 2}O with D{sub 2}O prolongs the lifetime of lipid-water and lipid-water-lipid interactions, which is reflected in a significantly slower TDFS kinetics. Combining TDFS measurements in H{sub 2}O and D{sub 2}O hydrated bilayers with atomistic molecular dynamics (MD) simulations provides a unique tool for characterization of the hydrogen bonding at the acylgroup level of lipid bilayers. In this work, we use this approach to study the influence of fluoride anions on the properties of cationic bilayers composed of trimethylammonium-propane (DOTAP). The results obtained for DOTAP are confronted with those for neutral phosphatidylcholine (DOPC) bilayers. Both in DOTAP and DOPC H{sub 2}O/D{sub 2}O exchange prolongs hydrogen-bonding lifetime and does not disturb bilayer structure. These results are confirmed by MD simulations. TDFS experiments show, however, that for DOTAP this effect is cancelled in the presence of fluoride ions. We interpret these results as evidence that strongly hydrated fluoride is able to steal water molecules that bridge lipid carbonyls. Consequently, when attracted to DOTAP bilayer, fluoride disrupts the local hydrogen-bonding network, and the differences in TDFS kinetics between H{sub 2}O and D{sub 2}O hydrated bilayers are no longer observed. A distinct behavior of fluoride is also evidenced by MD simulations, which show different lipid-ion binding for Cl{sup ?} and F{sup ?}.

  2. A comparison of neutron scattering studies and computer simulations of polymer melts

    E-Print Network [OSTI]

    Utah, University of

    A comparison of neutron scattering studies and computer simulations of polymer melts G.D. Smith a; in ®nal form 22 May 2000 Abstract Neutron scattering and computer simulations are powerful tools in particular. When neutron scattering studies and quan- titative atomistic molecular dynamics simulations

  3. MOLECULAR DYNAMICS SIMULATION OF HETEROGENEOUS NUCLEATION OF LIQUID DROPLET ON SOLID SURFACE

    E-Print Network [OSTI]

    Maruyama, Shigeo

    such as the quantum dot generation. We have simulated the equilibrium liquid droplet on the solid surface simulation on the bubble nucleation process on the solid surface [2]. In the meantime, direct molecular

  4. Simulation of hydrology and population dynamics of Anopheles mosquitoes around the Koka Reservoir in Ethiopia

    E-Print Network [OSTI]

    Endo, Noriko S.M. Massachusetts Institute of Technology

    2014-01-01T23:59:59.000Z

    This thesis applies the HYDRology, Entomology and MAlaria Transmission Simulator (HYDREMATS) to the environment around a water resources reservoir in Ethiopia. HYDREMATS was modified to simulate the local hydrology and the ...

  5. The Trp Cage: Folding Kinetics and Unfolded State Topology via Molecular Dynamics Simulations

    E-Print Network [OSTI]

    Snow, Christopher

    , ) 91 ps-1). The Folding@Home distributed computing project was used to generate an aggregate simulation

  6. Nonlinear Theoretical Tools for Fusion-related Microturbulence: Historical Evolution, and Recent Applications to Stochastic Magnetic Fields, Zonal-flow Dynamics, and Intermittency

    SciTech Connect (OSTI)

    J.A. Krommes

    2009-05-19T23:59:59.000Z

    Fusion physics poses an extremely challenging, practically complex problem that does not yield readily to simple paradigms. Nevertheless, various of the theoretical tools and conceptual advances emphasized at the KaufmanFest 2007 have motivated and/or found application to the development of fusion-related plasma turbulence theory. A brief historical commentary is given on some aspects of that specialty, with emphasis on the role (and limitations) of Hamiltonian/symplectic approaches, variational methods, oscillation-center theory, and nonlinear dynamics. It is shown how to extract a renormalized ponderomotive force from the statistical equations of plasma turbulence, and the possibility of a renormalized K-? theorem is discussed. An unusual application of quasilinear theory to the problem of plasma equilibria in the presence of stochastic magnetic fields is described. The modern problem of zonal-flow dynamics illustrates a confluence of several techniques, including (i) the application of nonlinear-dynamics methods, especially center-manifold theory, to the problem of the transition to plasma turbulence in the face of self-generated zonal flows; and (ii) the use of Hamiltonian formalism to determine the appropriate (Casimir) invariant to be used in a novel wave-kinetic analysis of systems of interacting zonal flows and drift waves. Recent progress in the theory of intermittent chaotic statistics and the generation of coherent structures from turbulence is mentioned, and an appeal is made for some new tools to cope with these interesting and difficult problems in nonlinear plasma physics. Finally, the important influence of the intellectually stimulating research environment fostered by Prof. Allan Kaufman on the author's thinking and teaching methodology is described.

  7. Buildings Performance Database Analysis Tools | Department of...

    Broader source: Energy.gov (indexed) [DOE]

    Save Consumers Billions Tools EnergyPlus Whole Building Energy Simulation OpenStudio Energy Simulation Application Suite Buildings Performance Database Building Energy...

  8. Challenges in Simulation of Aerodynamics, Hydrodynamics, and Mooring-Line Dynamics of Floating Offshore Wind Turbines

    SciTech Connect (OSTI)

    Matha, D.; Schlipf, M.; Cordle, A.; Pereira, R.; Jonkman, J.

    2011-10-01T23:59:59.000Z

    This paper presents the current major modeling challenges for floating offshore wind turbine design tools and describes aerodynamic and hydrodynamic effects due to rotor and platform motions and usage of non-slender support structures.

  9. Early maturation processes in coal. Part 2: Reactive dynamics simulations using the ReaxFF reactive force field on Morwell Brown coal structures

    E-Print Network [OSTI]

    Goddard III, William A.

    for each source rock. This allowed the bulk rate of oil and gas generation for a source rockEarly maturation processes in coal. Part 2: Reactive dynamics simulations using the ReaxFF reactive

  10. Investigation of Protein Folding by Using Combined Method of Molecular Dynamics and Monte Carlo Simulations.

    E-Print Network [OSTI]

    Liao, Jun-min

    2006-01-01T23:59:59.000Z

    ??We used the combination of molecular dynamics and Monte Carlo method to investigate protein folding problems. The environments of proteins are very big, and often… (more)

  11. User Guide for PV Dynamic Model Simulation Written on PSCAD Platform

    SciTech Connect (OSTI)

    Muljadi, E.; Singh, M.; Gevorgian, V.

    2014-11-01T23:59:59.000Z

    This document describes the dynamic photovoltaic model developed by the National Renewable Energy Laboratory and is intended as a guide for users of these models.

  12. Dynamic Simulation Studies of the Frequency Response of the Three U.S. Interconnections with Increased Wind Generation

    SciTech Connect (OSTI)

    Mackin, Peter; Daschmans, R.; Williams, B.; Haney, B.; Hung, R.; Ellis, J.

    2010-12-20T23:59:59.000Z

    Utility Systems Efficiencies, Inc. was tasked by Lawrence Berkeley National Laboratory (LBNL) to conduct dynamic simulation studies of the three U.S. interconnections (Eastern, Western, and Texas). The simulations were prepared in support of LBNL's project for the Federal Energy Regulatory Commission to study frequency-response-related issues that must be addressed to operate the power system reliably with large amounts of variable renewable generation. The objective of the simulation studies of each interconnection was to assess the effects of different amounts of wind generation on frequency behavior of each interconnection following a sudden loss of generation. The scenarios created to study these effects considered an operating circumstance in which system load is at or close to its minimum. The event studied was the sudden loss of the largest amount of generation recorded within each interconnection. The simulations calculated the impact of this event on interconnection frequency for three levels of wind generation. In addition to varying the amount of wind generation, the simulations varied the amount of operating reserves between a high level representative of current operating practices and a low level representative of the minimum required by present operating rules.

  13. advanced beam-dynamics simulation: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    . . . . 18 3.4.1 Heat Exchanger - Code description . . . . . . . . . . . . . . . 18 3.4.2 Simulation ResultsADVANCED POWER PLANT MODELING WITH APPLICATIONS TO THE ADVANCED BOILING...

  14. Best practices for system dynamics model design and construction with powersim studio.

    SciTech Connect (OSTI)

    Malczynski, Leonard A.

    2011-06-01T23:59:59.000Z

    This guide addresses software quality in the construction of Powersim{reg_sign} Studio 8 system dynamics simulation models. It is the result of almost ten years of experience with the Powersim suite of system dynamics modeling tools (Constructor and earlier Studio versions). It is a guide that proposes a common look and feel for the construction of Powersim Studio system dynamics models.

  15. Parallel contact detection algorithm for transient solid dynamics simulations using PRONTO3D

    SciTech Connect (OSTI)

    Attaway, S.W.; Hendrickson, B.A.; Plimpton, S.J. [and others

    1996-09-01T23:59:59.000Z

    An efficient, scalable, parallel algorithm for treating material surface contacts in solid mechanics finite element programs has been implemented in a modular way for MIMD parallel computers. The serial contact detection algorithm that was developed previously for the transient dynamics finite element code PRONTO3D has been extended for use in parallel computation by devising a dynamic (adaptive) processor load balancing scheme.

  16. Results of a Neutronic Simulation of HTR-Proteus Core 4.2 using PEBBED and other INL Reactor Physics Tools: FY-09 Report

    SciTech Connect (OSTI)

    Hans D. Gougar

    2009-08-01T23:59:59.000Z

    The Idaho National Laboratory’s deterministic neutronics analysis codes and methods were applied to the computation of the core multiplication factor of the HTR-Proteus pebble bed reactor critical facility. A combination of unit cell calculations (COMBINE-PEBDAN), 1-D discrete ordinates transport (SCAMP), and nodal diffusion calculations (PEBBED) were employed to yield keff and flux profiles. Preliminary results indicate that these tools, as currently configured and used, do not yield satisfactory estimates of keff. If control rods are not modeled, these methods can deliver much better agreement with experimental core eigenvalues which suggests that development efforts should focus on modeling control rod and other absorber regions. Under some assumptions and in 1D subcore analyses, diffusion theory agrees well with transport. This suggests that developments in specific areas can produce a viable core simulation approach. Some corrections have been identified and can be further developed, specifically: treatment of the upper void region, treatment of inter-pebble streaming, and explicit (multiscale) transport modeling of TRISO fuel particles as a first step in cross section generation. Until corrections are made that yield better agreement with experiment, conclusions from core design and burnup analyses should be regarded as qualitative and not benchmark quality.

  17. Comparison of four models simulating phosphorus dynamics in LakeVnern,Sweden Hydrology and Earth System Sciences, 8(6), 11531163 (2004) EGU

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Comparison of four models simulating phosphorus dynamics in LakeVänern,Sweden 1153 Hydrology dynamics in Lake Vänern, Sweden Magnus Dahl1 and B. Charlotta Pers2 1 Department of Chemical Engineering, Karlstad University, SE651 88 Karlstad, Sweden 2 Swedish Meteorological and Hydrological Institute, SE601

  18. WAKE-FIELDS AND BEAM DYNAMICS SIMULATIONS C.J. Glasman & R.M. Jones; Cockcroft Institute, Daresbury, WA4 4AD, UK;

    E-Print Network [OSTI]

    /m and is known as the baseline configura- tion document (BCD). However, here we investigate the electromagnetic simulated in detail using paral- lel finite difference and finite element codes [7, 8] and this data has been used as input for beam dynamics simulations, using the code LIAR [9], which tracks multi

  19. Ab initio molecular dynamics simulations of ion-solid interactions in Gd2Zr2O7 and Gd2Ti2O7

    SciTech Connect (OSTI)

    Wang, X J [University of Electronic Science and Technology of China (UESTC); Xiao, Haiyan [University of Tennessee, Knoxville (UTK); Zu, X T [University of Electronic Science and Technology of China (UESTC); Zhang, Yanwen [ORNL; Weber, William J [ORNL

    2013-01-01T23:59:59.000Z

    The development of ab initio molecular dynamics (AIMD) method has made it a powerful tool in describing ion-solid interactions in materials, with identification determination of threshold displacement energies with ab initio accuracy, and prediction of new mechanism for defect generation and new defective states that are different from classical molecular dynamics (MD) simulations. In the present work, this method is employed to study the low energy recoil events in Gd2Zr2O7 and Gd2Ti2O7. The weighted average threshold displacement energies in Gd2Zr2O7 are determined to be 38.8 eV for Gd, 41.4 eV for Zr, 18.6 eV for O48f, and 15.6 eV for O8b, which are smaller than the respective values of 41.8, >53.8, 22.6 and 16.2 eV in Gd2Ti2O7. It reveals that all the ions in Gd2Zr2O7 are more easily displaced than those in Gd2Ti2O7, and anion order-disorder are more likely to be involved in the displacement events than cation disordering. The average charge transfer from the primary knock-on atom to its neighbors is estimated to be ~0.15, ~0.11-0.27 and ~0.1-0.13 |e| for Gd, Zr (or Ti), and O, respectively. Negligence of the charge transfer in the interatomic potentials may result in the larger threshold displacement energies in classical MD.

  20. Anharmonic lattice dynamics of Ag2O studied by inelastic neutron scattering and first-principles molecular dynamics simulations

    SciTech Connect (OSTI)

    Lan, Tian [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Li, Chen [ORNL] [ORNL; Niedziela, Jennifer L [ORNL] [ORNL; Smith, Hillary [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Abernathy, Douglas L [ORNL] [ORNL; Rossman, George [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Fultz, B. [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena

    2014-01-01T23:59:59.000Z

    Inelastic neutron scattering measurements on silver oxide (Ag2O) with the cuprite structure were performed at temperatures from 40 to 400 K, and Fourier transform far-infrared spectra were measured from 100 to 300 K. The measured phonon densities of states and the infrared spectra showed unusually large energy shifts with temperature, and large linewidth broadenings. First principles molecular dynamics (MD) calculations were performed at various temperatures, successfully accounting for the negative thermal expansion (NTE) and local dynamics. Using the Fourier-transformed velocity autocorrelation method, the MD calculations reproduced the large anharmonic effects of Ag2O, and were in excellent agreement with the neutron scattering data. The quasiharmonic approximation (QHA) was less successful in accounting for much of the phonon behavior. The QHA could account for some of the NTE below 250 K, although not at higher temperatures. Strong anharmonic effects were found for both phonons and for the NTE. The lifetime broadenings of Ag2O were explained by anharmonic perturbation theory, which showed rich interactions between the Ag-dominated modes and the O-dominated modes in both up- and down-conversion processes.

  1. Large scale test simulations using the Virtual Environment for Test Optimization (VETO)

    SciTech Connect (OSTI)

    Klenke, S.E.; Heffelfinger, S.R.; Bell, H.J.; Shierling, C.L.

    1997-10-01T23:59:59.000Z

    The Virtual Environment for Test Optimization (VETO) is a set of simulation tools under development at Sandia to enable test engineers to do computer simulations of tests. The tool set utilizes analysis codes and test information to optimize design parameters and to provide an accurate model of the test environment which aides in the maximization of test performance, training, and safety. Previous VETO effort has included the development of two structural dynamics simulation modules that provide design and optimization tools for modal and vibration testing. These modules have allowed test engineers to model and simulate complex laboratory testing, to evaluate dynamic response behavior, and to investigate system testability. Further development of the VETO tool set will address the accurate modeling of large scale field test environments at Sandia. These field test environments provide weapon system certification capabilities and have different simulation requirements than those of laboratory testing.

  2. A new shared-memory programming paradigm for molecular dynamics simulations on the Intel Paragon

    SciTech Connect (OSTI)

    D`Azevedo, E.F.; Romine, C.H.

    1994-12-01T23:59:59.000Z

    This report describes the use of shared memory emulation with DOLIB (Distributed Object Library) to simplify parallel programming on the Intel Paragon. A molecular dynamics application is used as an example to illustrate the use of the DOLIB shared memory library. SOTON-PAR, a parallel molecular dynamics code with explicit message-passing using a Lennard-Jones 6-12 potential, is rewritten using DOLIB primitives. The resulting code has no explicit message primitives and resembles a serial code. The new code can perform dynamic load balancing and achieves better performance than the original parallel code with explicit message-passing.

  3. A low diffusive Lagrange-remap scheme for the simulation of violent air-water free-surface flows.

    E-Print Network [OSTI]

    Boyer, Edmond

    . The evolution of the interfaces between phases and the consecutive complex dynamics need to be simulatedA low diffusive Lagrange-remap scheme for the simulation of violent air-water free-surface flows. Introduction Simulation of free surface flows knows an increasing interest as an essential predictive tool

  4. Evaluating the learning effectiveness of using simulations in software project management education: results from a twice replicated experiment

    E-Print Network [OSTI]

    Krivobokova, Tatyana

    Evaluating the learning effectiveness of using simulations in software project management education replicated experiment that evaluates the learning effectiveness of using a process simulation model a System Dynamics simulation model, the control group used the well-known COCOMO model as a predictive tool

  5. Study of iron structure stability in high temperature molten lead-bismuth eutectic with oxygen injection using molecular dynamics simulation

    SciTech Connect (OSTI)

    Arkundato, Artoto [Physics Department, Faculty of Mathematical and Natural Sciences, Jember University, Jl. Kalimantan 37 Jember (Indonesia); Su'ud, Zaki [Physics Department, Faculty of Mathematical and Natural Sciences, Bandung Institute of Technology, Jl. Ganesha 10, Bandung (Indonesia); Sudarko [Chemistry Department, Faculty of Mathematical and Natural Sciences, Jember University, Jl. Kalimantan 37 Jember (Indonesia); Shafii, Mohammad Ali [Physics Department, Faculty of Mathematical and Natural Sciences, Andalas University, Padang (Indonesia); Celino, Massimo [ENEA, CR Casaccia, Via Anguillarese 301, Rome (Italy)

    2014-09-30T23:59:59.000Z

    Corrosion of structural materials in high temperature molten lead-bismuth eutectic is a major problem for design of PbBi cooled reactor. One technique to inhibit corrosion process is to inject oxygen into coolant. In this paper we study and focus on a way of inhibiting the corrosion of iron using molecular dynamics method. For the simulation results we concluded that effective corrosion inhibition of iron may be achieved by injection 0.0532 wt% to 0.1156 wt% oxygen into liquid lead-bismuth. At this oxygen concentration the structure of iron material will be maintained at about 70% in bcc crystal structure during interaction with liquid metal.

  6. Simulation of the dynamic behaviour of a geared transmission on hydrodynamic journal bearings

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    and bearings, oil injection, thermal effects, non Newtonian lubricant, etc. On the other hand, the dynamic whose reactions are calculated solving the lubrication equation presented in [3] under the short bearing

  7. Dynamics of a globular protein and its hydration water studied by neutron scattering and MD simulations

    E-Print Network [OSTI]

    Chen, Sow-Hsin

    2010-01-01T23:59:59.000Z

    This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling ...

  8. On the Consistency of Approximate Quantum Dynamics Simulation Methods for Vibrational Spectra in the Condensed Phase

    E-Print Network [OSTI]

    Rossi, Mariana; Paesani, Francesco; Bowman, Joel; Ceriotti, Michele

    2014-01-01T23:59:59.000Z

    Including quantum mechanical effects on the dynamics of nuclei in the condensed phase is challenging, because the complexity of exact methods grows exponentially with the number of quantum degrees of freedom. Efforts to circumvent these limitations can be traced down to two approaches: methods that treat a small subset of the degrees of freedom with rigorous quantum mechanics, considering the rest of the system as a static or classical environment, and methods that treat the whole system quantum mechanically, but using approximate dynamics. Here we perform a systematic comparison between these two philosophies for the description of quantum effects in vibrational spectroscopy, taking the Embedded Local Monomer (LMon) model and a mixed quantum-classical (MQC) model as representatives of the first family of methods, and centroid molecular dynamics (CMD) and thermostatted ring polymer molecular dynamics (TRPMD) as examples of the latter. We use as benchmarks D$_2$O doped with HOD and pure H$_2$O at three distinc...

  9. Trends in Ln(III) Sorption to Quartz Assessed by Molecular Dynamics Simulations and Laser Induced Flourescence Studies

    SciTech Connect (OSTI)

    Kuta, Jadwiga; Wander, Matthew C F.; Wang, Zheming; Jiang, Siduo; Wall, Nathalie; Clark, Aurora E.

    2011-11-08T23:59:59.000Z

    Molecular dynamics simulations were performed to examine trends in trivalent lanthanide [Ln(III)] sorption to quartz surface SiOH0 and SiO- sites across the 4f period. Complementary laser induced fluorescence studies examined Eu(III) sorption to quartz at varying ionic strength such that the surface sorbed species could be extrapolated at zero ionic strength, the conditions under which the simulations are performed. This allowed for direct comparison of the data, enabling a molecular understanding of the surface sorbed species and the role of the ion surface charge density upon the interfacial reactivity. Thus, this combined theoretical and experimental approach aids in the prediction of the fate of trivalent radioactive contaminants at temporary and permanent nuclear waste storage sites. Potential of mean force molecular dynamics, as well as simulations of pre-sorbed Ln(III) species agrees with the spectroscopic study of Eu(III) sorption, indicating that strongly bound inner-sphere complexes are formed upon sorption to an SiO- site. The coordination shell of the ion contains 6-7 waters of hydration and it is predicted that surface OH groups dissociate from the quartz and bind within the inner coordination shell of Eu(III). Molecular simulations predict less-strongly bound inner2 sphere species in early lanthanides and more strongly bound species in late lanthanides, following trends in the ionic radius of the 4f ions. The participation of surface dissociated OHgroups within the inner coordination shell of the Ln(III) ion is, however, consistent across the series studied. Sorption to a fully protonated quartz surface is not predicted to be favorable by any Ln(III), except perhaps Lu.

  10. A Finite Element-Multibody Dynamics Co-simulation Methodology Applied to FAST

    E-Print Network [OSTI]

    Suryakumar, Vishvas Samuel

    2013-05-02T23:59:59.000Z

    . To synchronize the coupling variables, a Gauss-Seidel type iterative algorithm is used. The resulting fixed-point iterations are accelerated using Aitken’s adaptive relaxation technique. The methodology is evaluated for FAST, a wind turbine aeroelastic simulation...

  11. A microphysical and dynamical comparison of the observed and simulated structure of a Florida area thunderstorm

    E-Print Network [OSTI]

    Chadwick, Virginia Alyson

    2003-01-01T23:59:59.000Z

    , but often overestimated the magnitude of the horizontal components and underestimated those of the vertical components. Despite possessing weaker updrafts than found in the observed storm, the simulation produced stronger, deeper cores with inflated...

  12. An efficient algorithm for blade loss simulations applied to a high-order rotor dynamics problem

    E-Print Network [OSTI]

    Parthasarathy, Nikhil Kaushik

    2004-09-30T23:59:59.000Z

    In this thesis, a novel approach is presented for blade loss simulation of an aircraft gas turbine rotor mounted on rolling element bearings with squeeze film dampers, seal rub and enclosed in a flexible housing. The modal truncation augmentation...

  13. Molecular Dynamics Simulation of Damage Cascade Formation in Ion Bombarded Solids

    E-Print Network [OSTI]

    Chen, Di

    2012-10-19T23:59:59.000Z

    /Molecular Massively Parallel Simulator). In one subtask, we studied damage cascade interactions caused by two 2 keV Si atoms simultaneously bombarding a crystalline Si substrate. We found that the enhanced displacement creation appears primarily in the thermal spike...

  14. FAST STATIC AND DYNAMIC GRID LEVEL THERMAL SIMULATION CONSIDERING TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY OF SILICON

    E-Print Network [OSTI]

    Ziabari, Amirkoushyar

    2012-01-01T23:59:59.000Z

    heat diffusion equation has been conventionally handled by grid-grids and an approximate delta function simulating a point heatgrid size of 64×64. To obtain transient thermal mask an impulse heat

  15. Transverse effects in plasma wakefield acceleration at FACET - Simulation studies

    SciTech Connect (OSTI)

    Adli, E.; Hogan, M.; Frederico, J.; Litos, M. D.; An, W.; Mori, W. [Department of Physics, University of Oslo, N-0316 Oslo (Norway); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); University of California Los Angeles, Los Angeles, CA 90024 (United States)

    2012-12-21T23:59:59.000Z

    We investigate transverse effects in the plasma-wakefield acceleration experiments planned and ongoing at FACET. We use PIC simulation tools, mainly QuickPIC, to simulate the interaction of the drive electron beam and the plasma. In FACET a number of beam dynamics knobs, including dispersion and bunch length knobs, can be used to vary the beam transverse characteristics in the plasma. We present simulation results and the status of the FACET experimental searches.

  16. Planning Tool for Strategic Evaluation of Facility Plans - 13570

    SciTech Connect (OSTI)

    Magoulas, Virginia; Cercy, Michael [Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808 (United States)] [Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808 (United States); Hall, Irin [Newport News Shipbuilding, 4101 Washington Ave., Newport News, VA 23607 (United States)] [Newport News Shipbuilding, 4101 Washington Ave., Newport News, VA 23607 (United States)

    2013-07-01T23:59:59.000Z

    Savannah River National Laboratory (SRNL) has developed a strategic planning tool for the evaluation of the utilization of its unique resources for processing and research and development of nuclear materials. The Planning Tool is a strategic level tool for assessing multiple missions that could be conducted utilizing the SRNL facilities and showcasing the plan. Traditional approaches using standard scheduling tools and laying out a strategy on paper tended to be labor intensive and offered either a limited or cluttered view for visualizing and communicating results. A tool that can assess the process throughput, duration, and utilization of the facility was needed. SRNL teamed with Newport News Shipbuilding (NNS), a division of Huntington Ingalls Industries, to create the next generation Planning Tool. The goal of this collaboration was to create a simulation based tool that allows for quick evaluation of strategies with respect to new or changing missions, and clearly communicates results to the decision makers. This tool has been built upon a mature modeling and simulation software previously developed by NNS. The Planning Tool provides a forum for capturing dependencies, constraints, activity flows, and variable factors. It is also a platform for quickly evaluating multiple mission scenarios, dynamically adding/updating scenarios, generating multiple views for evaluating/communicating results, and understanding where there are areas of risks and opportunities with respect to capacity. The Planning Tool that has been developed is useful in that it presents a clear visual plan for the missions at the Savannah River Site (SRS). It not only assists in communicating the plans to SRS corporate management, but also allows the area stakeholders a visual look at the future plans for SRS. The design of this tool makes it easily deployable to other facility and mission planning endeavors. (authors)

  17. Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments

    E-Print Network [OSTI]

    Probe, Austin Breien

    2013-12-03T23:59:59.000Z

    ., Analytical Mechanics of Space Systems , American Institute of Aeronautics and Astronautics, Reston, VA, 2009. [3] Hurtado, J., Kinematic and Kinetic Principles , Lulu Press, Inc., Raleigh, N.C. [4] Macron Dynamics Inc., 100 Phyllis Drive, Croydon... specifically like to thank Dr. J.-C. Liou, our technical adviser, for his support. iv TABLE OF CONTENTS Page ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii DEDICATION...

  18. 1310 / JOURNAL OF ENGINEERING MECHANICS / DECEMBER 2001 DYNAMIC LOAD SIMULATOR: DEVELOPMENT OF A PROTOTYPE

    E-Print Network [OSTI]

    Kareem, Ahsan

    and inertial loads are introduced to model the effects of wind, waves, or earthquakes. On the other hand, DLS, respectively. Some of the problems with the use of wind tunnels and wave tanks for dynamic testing arise from the inconvenience in modeling structural behavior due to similitude mismatch. Both wind tun- nels and wave tanks

  19. A next-generation modeling capability assesses wind turbine array fluid dynamics and aeroelastic simulations

    E-Print Network [OSTI]

    A next-generation modeling capability assesses wind turbine array fluid dynamics and aeroelastic of multi-megawatt turbines requires a new generation of modeling capability to assess individual turbine. Key Result The work is generating several models, including actuator line models of several wind

  20. Preliminary Comparison of Reaction Rate theory and Object Kinetic Monte Carlo Simulations of Defect Cluster Dynamics under Irradiation

    SciTech Connect (OSTI)

    Stoller, Roger E [ORNL; Golubov, Stanislav I [ORNL; Becquart, C. S. [Universite de Lille; Domain, C. [EDF R& D, Clamart, France

    2006-09-01T23:59:59.000Z

    The multiscale modeling scheme encompasses models from the atomistic to the continuum scale. Phenomena at the mesoscale are typically simulated using reaction rate theory (RT), Monte Carlo (MC), or phase field models. These mesoscale models are appropriate for application to problems that involve intermediate length scales ( m to >mm), and timescales from diffusion (~ s) to long-term microstructural evolution (~years). Phenomena at this scale have the most direct impact on mechanical properties in structural materials of interest to nuclear energy systems, and are also the most accessible to direct comparison between the results of simulations and experiments. Recent advances in computational power have substantially expanded the range of application for MC models. Although the RT and MC models can be used simulate the same phenomena, many of the details are handled quite differently in the two approaches. A direct comparison of the RT and MC descriptions has been made in the domain of point defect cluster dynamics modeling, which is relevant to both the nucleation and evolution of radiation-induced defect structures. The relative merits and limitations of the two approaches are discussed, and the predictions of the two approaches are compared for specific irradiation conditions.

  1. Computational fluid dynamics simulation of the air/suppressant flow in an uncluttered F18 engine nacelle

    SciTech Connect (OSTI)

    Lopez, A.R.; Gritzo, L.A.; Hassan, B.

    1997-06-01T23:59:59.000Z

    For the purposes of designing improved Halon-alternative fire suppression strategies for aircraft applications, Computational Fluid Dynamics (CFD) simulations of the air flow, suppressant transport, and air-suppressant mixing within an uncluttered F18 engine nacelle were performed. The release of inert gases from a Solid Propellant Gas Generator (SPGG) was analyzed at two different injection locations in order to understand the effect of injection position on the flow patterns and the mixing of air and suppression agent. An uncluttered engine nacelle was simulated to provide insight into the global flow features as well as to promote comparisons with previous nacelle fire tests and recent water tunnel tests which included little or no clutter. Oxygen concentration levels, fuel/air residence times that would exist if a small fuel leak were present, velocity contours, and streamline patterns are presented inside the engine nacelle. The numerical results show the influence of the gent release location on regions of potential flame extinction due to oxygen inerting and high flame strain. The occurrence of inflow through the exhaust ducts on the aft end of the nacelle is also predicted. As expected, the predicted oxygen concentration levels were consistently higher than the measured levels since a fire was not modeled in this analysis. Despite differences in the conditions of these simulations and the experiments, good agreement was obtained between the CFD predictions and the experimental measurements.

  2. Dynamic Simulation and Analysis of Heating Energy Consumption in a Residential Building

    E-Print Network [OSTI]

    Liu, J.; Yang, M.; Zhao, X.; Zhu, N.

    2006-01-01T23:59:59.000Z

    In winter, much of the building energy is used for heating in the north region of China. In this study, the heating energy consumption of a residential building in Tianjin during a heating period was simulated by using the EnergyPlus energy...

  3. Effects of confinement on water structure and dynamics and on proton transport: a molecular simulation study

    E-Print Network [OSTI]

    Hirunsit, Pussana

    2009-05-15T23:59:59.000Z

    O-H bonds are parallel to the surface. These orientations agree with those found in our MD simulation results. The calculated energy barriers for proton transfer of the confined H3O+-(H2O) complexes between two graphite model surfaces suggest...

  4. Understanding graphene production by ionic surfactant exfoliation: A molecular dynamics simulation study

    E-Print Network [OSTI]

    Simons, Jack

    simulated sodium dodecyl sulfate (SDS) surfactant/water þ bilayer graphene mixture system to investigate two attention is being paid to its potential applications, such as transistors,9 electrode,10 solar cells,11 elec- tronic structure of graphene.18 Recently, an alternative top-down liquid exfoliation approach

  5. Forward Dynamics, Elimination Methods, and Formulation Sti ness in Robot Simulation

    E-Print Network [OSTI]

    Pai, Dinesh

    -line applications such as virtual environ- ments for operator training, predictive displays for time by contacts with the environment. For the simulation of such robots, the elimination method leads to an ODE by the joint actuators, q is the N 1 vector of joint variables _q and q are the joint velocities

  6. Integrating Models and Simulations of Continuous Dynamics into SysML

    E-Print Network [OSTI]

    In this paper, we combine modeling constructs from SysML and Modelica to improve the support for Model, structures, functions, and behaviors. Complementing these SysML constructs, the Modelica language has emerged and the corresponding Modelica models; and the integration of simulation experiments with other SysML constructs

  7. Computational Fluid Dynamics Simulation of Green Water Around a Two-dimensional Platform

    E-Print Network [OSTI]

    Zhao, Yucheng

    2010-07-14T23:59:59.000Z

    An interface-preserving level set method is incorporated into the Reynolds-Averaged Navier-Stokes (RANS) numerical method to simulate the application of the green water phenomena around a platform and the breaking wave above the deck. In the present...

  8. The solvation of Cl , Br , and I in acetonitrile clusters: Photoelectron spectroscopy and molecular dynamics simulations

    E-Print Network [OSTI]

    Perera, Lalith

    The solvation of Cl , Br , and I in acetonitrile clusters: Photoelectron spectroscopy and molecular in acetonitrile clusters CH3CN n with n 1­33, 1­40, and 1­55, respectively, taken with 7.9 eV photon energy. Anion simulations of halide­acetonitrile clusters reproduce the measured stabilization energies and generate full

  9. Atomistic Time-Domain Simulations of Light-Harvesting and Charge-Transfer Dynamics in Novel Nanoscale Materials for Solar Hydrogen Production.

    SciTech Connect (OSTI)

    Prezhdo, Oleg V.

    2012-03-22T23:59:59.000Z

    Funded by the DOE grant (i) we continued to study and analyze the atomistic detail of the electron transfer (ET) across the chromophore-TiO2 interface in Gratzel cell systems for solar hydrogen production. (ii) We extensively investigated the nature of photoexcited states and excited state dynamics in semiconductor quantum dots (QD) designed for photovoltaic applications. (iii) We continued a newly initiated research direction focusing on excited state properties and electron-phonon interactions in nanoscale carbon materials. Over the past year, the results of the DOE funded research were summarized in 3 review articles. 12 original manuscripts were written. The research results were reported in 28 invited talks at conferences and university seminars. 20 invitations were accepted for talks in the near future. 2 symposia at national and international meetings have being organized this year on topics closely related to the DOE funded project, and 2 more symposia have been planned for the near future. We summarized the insights into photoinduced dynamics of semiconductor QDs, obtained from our time-domain ab initio studies. QDs exhibit both molecular and bulk properties. Unlike either bulk or molecular materials, QD properties can be modified continuously by changing QD shape and size. However, the chemical and physical properties of molecular and bulk materials often contradict each other, which can lead to differing viewpoints about the behavior of QDs. For example, the molecular view suggests strong electron-hole and charge-phonon interactions, as well as slow energy relaxation due to mismatch between electronic energy gaps and phonon frequencies. In contrast, the bulk view advocates that the kinetic energy of quantum confinement is greater than electron-hole interactions, that charge-phonon coupling is weak, and that the relaxation through quasi-continuous bands is rapid. By synthesizing the bulk and molecular viewpoints, we clarified the controversies and provided a unified atomistic picture of the nature and dynamics of photoexcited states in semiconductor QDs. We also summarized our recent findings about the photoinduced electron dynamics at the chromophore-semiconductor interfaces from a time-domain ab initio perspective. The interface provides the foundation for a new, promising type of solar cell and presents a fundamentally important case study for several fields, including photo-, electro- and analytical chemistries, molecular electronics, and photography. Further, the interface offers a classic example of an interaction between an organic molecular species and an inorganic bulk material. Scientists employ different concepts and terminologies to describe molecular and solid states of matter, and these differences make it difficult to describe the interface with a single model. At the basic atomistic level of description, however, this challenge can be largely overcome. Recent advances in non-adiabatic molecular dynamics and time-domain density functional theory have created a unique opportunity for simulating the ultrafast, photoinduced processes on a computer very similar to the way that they occur in nature. These state-of-the-art theoretical tools offered a comprehensive picture of a variety of electron transfer processes that occur at the interface, including electron injection from the chromophore to the semiconductor, electron relaxation and delocalization inside the semiconductor, back-transfer of the electron to the chromophore and to the electrolyte, and regeneration of the neutral chromophore by the electrolyte. The ab initio time-domain modeling is particularly valuable for understanding these dynamic features of the ultrafast electron transfer processes, which cannot be represented by a simple rate description. We demonstrated using symmetry adapted cluster theory with configuration interaction (SAC-CI) that charging of small PbSe nanocrystals (NCs) greatly modifies their electronic states and optical excitations. Conduction and valence band transitions that are not available in neutral NCs dominate

  10. Percussion tool

    DOE Patents [OSTI]

    Reed, Teddy R.

    2006-11-28T23:59:59.000Z

    A percussion tool is described and which includes a housing mounting a tool bit; a reciprocally moveable hammer borne by the housing and which is operable to repeatedly strike the tool bit; and a reciprocally moveable piston enclosed within the hammer and which imparts reciprocal movement to the reciprocally moveable hammer.

  11. Computational Tools for Accelerating Carbon Capture Process Development

    SciTech Connect (OSTI)

    Miller, David

    2013-01-01T23:59:59.000Z

    The goals of the work reported are: to develop new computational tools and models to enable industry to more rapidly develop and deploy new advanced energy technologies; to demonstrate the capabilities of the CCSI Toolset on non-proprietary case studies; and to deploy the CCSI Toolset to industry. Challenges of simulating carbon capture (and other) processes include: dealing with multiple scales (particle, device, and whole process scales); integration across scales; verification, validation, and uncertainty; and decision support. The tools cover: risk analysis and decision making; validated, high-fidelity CFD; high-resolution filtered sub-models; process design and optimization tools; advanced process control and dynamics; process models; basic data sub-models; and cross-cutting integration tools.

  12. NREL researchers are the first to use a high-performance com-puting tool for a large-eddy simulation of an entire wind plant.

    E-Print Network [OSTI]

    Denmark and Sweden and compared results with more than a year's worth of plant data.The simulated power at least 50% wastepaper, including 10% post consumer waste. NREL Develops Simulations forWind Plant Power-eddy simulation of an entire wind plant. Researchers at the National Renewable Energy Laboratory's (NREL) National

  13. Computer simulation plays an increasingly important role in engineering education as a tool for enhancing classroom learning. This research investigates the efficacy of using sim-

    E-Print Network [OSTI]

    Levinson, David M.

    the evaluation. Simulation in Education and Simula- tor of Network Growth (SONG 1.0) How learners learn though simulation Experimenting different strategies Learn from consequences of their own actions EducationalAbstract Computer simulation plays an increasingly important role in engineering education

  14. FT-ICR Reaction Experiments and Molecular Dynamics Simulations of Precursor Clusters for

    E-Print Network [OSTI]

    Maruyama, Shigeo

    . J. D, 9, 1-4, 385 (1999). 30 40 50 60 70 Number of Carbon Atoms Intensity(arbitrary) Noise (a carbon sample. 520 530 540 43 44 45 Number of Carbon Atoms Intensity(arbitrary) NiC38 ­ CoC38 ­ NiC38(NO mechanism of single walled carbon nanotubes is investigated through experimental and molecular dynamics

  15. Predictive Simulation and Design of Materials by Quasicontinuum and Accelerated Dynamics Methods

    SciTech Connect (OSTI)

    Luskin, Mitchell [University of Minnesota; James, Richard; Tadmor, Ellad

    2014-03-30T23:59:59.000Z

    This project developed the hyper-QC multiscale method to make possible the computation of previously inaccessible space and time scales for materials with thermally activated defects. The hyper-QC method combines the spatial coarse-graining feature of a finite temperature extension of the quasicontinuum (QC) method (aka “hot-QC”) with the accelerated dynamics feature of hyperdynamics. The hyper-QC method was developed, optimized, and tested from a rigorous mathematical foundation.

  16. Computer code for the atomistic simulation of lattice defects and dynamics. [COMENT code

    SciTech Connect (OSTI)

    Schiffgens, J.O.; Graves, N.J.; Oster, C.A.

    1980-04-01T23:59:59.000Z

    This document has been prepared to satisfy the need for a detailed, up-to-date description of a computer code that can be used to simulate phenomena on an atomistic level. COMENT was written in FORTRAN IV and COMPASS (CDC assembly language) to solve the classical equations of motion for a large number of atoms interacting according to a given force law, and to perform the desired ancillary analysis of the resulting data. COMENT is a dual-purpose intended to describe static defect configurations as well as the detailed motion of atoms in a crystal lattice. It can be used to simulate the effect of temperature, impurities, and pre-existing defects on radiation-induced defect production mechanisms, defect migration, and defect stability.

  17. Standing crop dynamics under simulated short-duration grazing at four stocking rates

    E-Print Network [OSTI]

    Casco, Jose Francisco

    1984-01-01T23:59:59.000Z

    temperature (4 C ) for the years 1981 and 1982 and the 30-year average for the period 1951-1982, from Easterwood Airport, College Station, Texas. 17 Table 3. Grazing cycles, dates, days grazed, number of animals used, and average weight for a simulated... variable occurred when stocking rate increased. c) No changes in the mean response variable occurred across grazing cycles. LITERATURE REVIEW Stocking Rate and Animal Relationships Stocking rate has been defined as the accumulative forage demand per...

  18. Numerical simulation of flow distribution for pebble bed high temperature gas cooled reactors

    E-Print Network [OSTI]

    Yesilyurt, Gokhan

    2004-09-30T23:59:59.000Z

    ?....................................................................................26 V CFD MODELLING ...................................................................................28 V.1 Computational Fluid Dynamics (CFD) ..........................................28 V.2 The History.... Hassan The premise of the work presented here is to use a common analytical tool, Computational Fluid Dynamics (CFD), along with different turbulence models. Eddy viscosity models as well as state-of-the-art Large Eddy Simulation (LES) were...

  19. SOWFA Super-Controller: A High-Fidelity Tool for Evaluating Wind Plant Control Approaches

    SciTech Connect (OSTI)

    Fleming, P.; Gebraad, P.; van Wingerden, J. W.; Lee, S.; Churchfield, M.; Scholbrock, A.; Michalakes, J.; Johnson, K.; Moriarty, P.

    2013-01-01T23:59:59.000Z

    This paper presents a new tool for testing wind plant controllers in the Simulator for Offshore Wind Farm Applications (SOWFA). SOWFA is a high-fidelity simulator for the interaction between wind turbine dynamics and the fluid flow in a wind plant. The new super-controller testing environment in SOWFA allows for the implementation of the majority of the wind plant control strategies proposed in the literature.

  20. Dealing with big circulation flow, small temperature difference based on verified dynamic model simulations of a hot water district heating system

    E-Print Network [OSTI]

    Zhong, L.

    2014-01-01T23:59:59.000Z

    DEALING WITH “BIG CIRCULATION FLOW RATE, SMALL TEMPERATURE DIFFERENCE” BASED ON VERIFIED DYNAMIC MODEL SIMULATIONS OF A HOT WATER DISTRICT HEATING SYSTEM Li Lian Zhong, Senior Sales Consultant, Danfoss Automatic Controls Management (Shanghai...) Co.,Ltd, Anshan, China ABSTRACT Dynamic models of an indirect hot water district heating system were developed based on the first principle of thermodynamics. The ideal model was verified by using measured operational data. The ideal...

  1. Broadband infrared and Raman probes of excited-state vibrational molecular dynamics; Simulation protocols based on loop diagram

    E-Print Network [OSTI]

    Konstantin E. Dorfman; Benjamin P. Fingerhut; Shaul Mukamel

    2013-05-23T23:59:59.000Z

    Vibrational motions in electronically excited states can be observed by either time and frequency resolved infrared absorption or by off resonant stimulated Raman techniques. Multipoint correlation function expressions are derived for both signals. Three representations for the signal which suggest different simulation protocols are developed. These are based on the forward and the backward propagation of the wavefunction, sum over state expansion using an effective vibration Hamiltonian and a semiclassical treatment of a bath. We show that the effective temporal ($\\Delta t$) and spectral ($\\Delta\\omega$) resolution of the techniques is not controlled solely by experimental knobs but also depends on the system dynamics being probed. The Fourier uncertainty $\\Delta\\omega\\Delta t>1$ is never violated.

  2. Dynamic simulation of the thermal and electrical behavior of a thermionic converter coupled to a solar concentrator

    SciTech Connect (OSTI)

    Perez, G. [CUAP-UAP, Puebla (Mexico). Centro de Investigaciones en Dispositivos Semiconductores; Estrada, C.A.; Cervantes, J.G. [UNAM, Temixco, Morelos (Mexico). Solar Energy Research Lab.

    1995-12-31T23:59:59.000Z

    A mathematical simulation for the dynamic thermal and electrical behavior of a thermionic converter coupled to a solar concentrator, is presented. The thermionic device is a Cesium-filled thermionic diode operating in the ignited mode. The emitter of the device is made of polycrystalline Rhenium and the collector of the device of Molybdenum. The solar concentrator is a parabolic dish. The designed emitter and collector temperatures are 1,850 K and 928 K, respectively. However, due to changes in ambient conditions, the collector efficiency varies and so does the system efficiency. This fact makes it necessary to evaluate the design of the system not just for one hour with constant conditions but also for a whole operating day. The paper presents plots for the emitter and collector thermionic device temperatures and power and voltage for a constant resistance load as a function of time.

  3. Interaction of Polar and Nonpolar Organic Pollutants with Soil Organic Matter: Sorption Experiments and Molecular Dynamics Simulation

    E-Print Network [OSTI]

    Ahmed, Ashour A; Aziz, Saadullah G; Hilal, Rifaat H; Elroby, Shaaban A; Al-Youbi, Abdulrahman O; Leinweber, Peter; Kühn, Oliver

    2014-01-01T23:59:59.000Z

    The fate of organic pollutants in the environment is influenced by several factors including the type and strength of their interactions with soil components especially SOM. However, a molecular level answer to the question How organic pollutants interact with SOM? is lacking. In order to explore mechanisms of this interaction, we have developed a new SOM model followed by carrying out molecular dynamics (MD) simulations in parallel with sorption experiments. The new SOM model comprises free SOM functional groups (carboxylic acid and naphthalene) as well as SOM cavities (with two different sizes), representing the soil voids, containing the same SOM functional groups. To examine the effect of the hydrophobicity on the interaction, the organic pollutants hexachlorobenzene (HCB, non-polar) and sulfanilamide (SAA, polar) were considered. The experimental and the theoretical outcomes explored four major points regarding sorption of SAA and HCB on soil. 1. The interaction depends on the SOM chemical composition mo...

  4. Structural, vibrational, and elastic properties of a calcium aluminosilicate glass from molecular dynamics simulations: The role of the potential

    SciTech Connect (OSTI)

    Bauchy, M., E-mail: bauchy@mit.edu [Concrete Sustainability Hub, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA and Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095 (United States)

    2014-07-14T23:59:59.000Z

    We study a calcium aluminosilicate glass of composition (SiO{sub 2}){sub 0.60}(Al{sub 2}O{sub 3}){sub 0.10}(CaO){sub 0.30} by means of molecular dynamics. To this end, we conduct parallel simulations, following a consistent methodology, but using three different potentials. Structural and elastic properties are analyzed and compared to available experimental data. This allows assessing the respective abilities of the potentials to produce a realistic glass. We report that, although all these potentials offer a reasonable glass structure, featuring tricluster oxygen atoms, their respective vibrational and elastic predictions differ. This allows us to draw some general conclusions about the crucial role, or otherwise, of the interaction potential in silicate systems.

  5. DREAM tool increases space weather predictions

    E-Print Network [OSTI]

    - 1 - DREAM tool increases space weather predictions April 13, 2012 Predicting space weather improved by new DREAM modeling tool Earth's radiation belts can now be studied with a new modeling tool DREAM comes into play. Radiation belt structure and dynamics revealed DREAM is a modeling tool

  6. Quantum molecular dynamics simulations of transport properties in liquid and dense-plasma plutonium

    SciTech Connect (OSTI)

    Kress, J. D.; Cohen, James S.; Kilcrease, D. P.; Horner, D. A.; Collins, L. A. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2011-02-15T23:59:59.000Z

    We have calculated the viscosity and self-diffusion coefficients of plutonium in the liquid phase using quantum molecular dynamics (QMD) and in the dense-plasma phase using orbital-free molecular dynamics (OFMD), as well as in the intermediate warm dense matter regime with both methods. Our liquid metal results for viscosity are about 40% lower than measured experimentally, whereas a previous calculation using an empirical interatomic potential (modified embedded-atom method) obtained results 3-4 times larger than the experiment. The QMD and OFMD results agree well at the intermediate temperatures. The calculations in the dense-plasma regime for temperatures from 50 to 5000 eV and densities about 1-5 times ambient are compared with the one-component plasma (OCP) model, using effective charges given by the average-atom code inferno. The inferno-OCP model results agree with the OFMD to within about a factor of 2, except for the viscosity at temperatures less than about 100 eV, where the disagreement is greater. A Stokes-Einstein relationship of the viscosities and diffusion coefficients is found to hold fairly well separately in both the liquid and dense-plasma regimes.

  7. Microscopic dynamics simulations of heavy-ion fusion reactions induced by neutron-rich nuclei

    E-Print Network [OSTI]

    Ning Wang; Li Ou; Yingxun Zhang; Zhuxia Li

    2014-06-04T23:59:59.000Z

    The heavy-ion fusion reactions induced by neutron-rich nuclei are investigated with the improved quantum molecular dynamics (ImQMD) model. With a subtle consideration of the neutron skin thickness of nuclei and the symmetry potential, the stability of nuclei and the fusion excitation functions of heavy-ion fusion reactions $^{16}$O+$^{76}$Ge, $^{16}$O+$^{154}$Sm, $^{40}$Ca+$^{96}$Zr and $^{132}$Sn+$^{40}$Ca are systematically studied. The fusion cross sections of these reactions at energies around the Coulomb barrier can be well reproduced by using the ImQMD model. The corresponding slope parameter of the symmetry energy adopted in the calculations is $L \\approx 78$ MeV and the surface energy coefficient is $g_{\\rm sur}=18\\pm 1.5$ MeVfm$^2$. In addition, it is found that the surface-symmetry term significantly influences the fusion cross sections of neutron-rich fusion systems. For sub-barrier fusion, the dynamical fluctuations in the densities of the reaction partners and the enhanced surface diffuseness at neck side result in the lowering of the fusion barrier.

  8. Lithium Ion Transport Mechanism in Ternary Polymer Electrolyte-Ionic Liquid Mixtures - A Molecular Dynamics Simulation Study

    E-Print Network [OSTI]

    Diddo Diddens; Andreas Heuer

    2013-02-20T23:59:59.000Z

    The lithium transport mechanism in ternary polymer electrolytes, consisting of PEO/LiTFSI and various fractions of the ionic liquid N-methyl-N-propylpyrrolidinium bis(trifluoromethane)sulfonimide, are investigated by means of MD simulations. This is motivated by recent experimental findings [Passerini et al., Electrochim. Acta 2012, 86, 330-338], which demonstrated that these materials display an enhanced lithium mobility relative to their binary counterpart PEO/LiTFSI. In order to grasp the underlying microscopic scenario giving rise to these observations, we employ an analytical, Rouse-based cation transport model [Maitra at al., PRL 2007, 98, 227802], which has originally been devised for conventional polymer electrolytes. This model describes the cation transport via three different mechanisms, each characterized by an individual time scale. It turns out that also in the ternary electrolytes essentially all lithium ions are coordinated by PEO chains, thus ruling out a transport mechanism enhanced by the presence of ionic-liquid molecules. Rather, the plasticizing effect of the ionic liquid contributes to the increased lithium mobility by enhancing the dynamics of the PEO chains and consequently also the motion of the attached ions. Additional focus is laid on the prediction of lithium diffusion coefficients from the simulation data for various chain lengths and the comparison with experimental data, thus demonstrating the broad applicability of our approach.

  9. Effect of bound state of water on hydronium ion mobility in hydrated Nafion using molecular dynamics simulations

    SciTech Connect (OSTI)

    Mabuchi, Takuya, E-mail: mabuchi@nanoint.ifs.tohoku.ac.jp [Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Tokumasu, Takashi [Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577 (Japan)

    2014-09-14T23:59:59.000Z

    We have performed a detailed analysis of the structural properties of the sulfonate groups in terms of isolated and overlapped solvation shells in the nanostructure of hydrated Nafion membrane using classical molecular dynamics simulations. Our simulations have demonstrated the correlation between the two different areas in bound water region, i.e., the first solvation shell, and the vehicular transport of hydronium ions at different water contents. We have employed a model of the Nafion membrane using the improved force field, which is newly modified and validated by comparing the density and water diffusivity with those obtained experimentally. The first solvation shells were classified into the two types, the isolated area and the overlapped area. The mean residence times of solvent molecules explicitly showed the different behaviors in each of those areas in terms of the vehicular transport of protons: the diffusivity of classical hydronium ions in the overlapped area dominates their total diffusion at lower water contents while that in the isolated area dominates for their diffusion at higher water contents. The results provided insights into the importance role of those areas in the solvation shells for the diffusivity of vehicular transport of hydronium ions in hydrated Nafion membrane.

  10. A Dynamic Simulation of the Indirect Land Use Implications of Recent Biofuel Production and Use in the United States.

    SciTech Connect (OSTI)

    Oladosu, Gbadebo A [ORNL] [ORNL; Kline, Keith L [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    The global indirect land use change (ILUC) implications of biofuel use in the United States of America (USA) from 2001 to 2010 are evaluated with a dynamic general equilibrium model. The effects of biofuels production on agricultural land area vary by year; from a net expansion of 0.17 ha per 1000 gallons produced (2002) to a net contraction of 0.13 ha per 1000 gallons (2018) in Case 1 of our simulation. In accordance with the general narrative about the implications of biofuel policy, agricultural land area increased in many regions of the world. However, oil-export dependent economies experienced agricultural land contraction because of reductions in their revenues. Reducing crude oil imports is a major goal of biofuel policy, but the land use change implications have received little attention in the literature. Simulations evaluating the effects of doubling supply elasticities for land and fossil resources show that these parameters can significantly influence the land use change estimates. Therefore, research that provides empirically-based and spatially-detailed agricultural land-supply curves and capability to project future fossil energy prices is critical for improving estimates of the effects of biofuel policy on land use.

  11. Molecular Dynamics Simulations of Tri-n-butyl-phosphate/n-Dodecane Mixture: Thermophysical Properties and Molecular Structure

    SciTech Connect (OSTI)

    de Almeida, Valmor F [ORNL; Cui, Shengting [ORNL; Khomami, Bamin [ORNL

    2014-01-01T23:59:59.000Z

    Molecular dynamics simulations of tri-n-butyl-phosphate (TBP)/n-dodecane mixture in the liquid phase have been carried out using two recently developed TBP force field models (J. Phys. Chem. B 2012, 116, 305) in combination with the all-atom optimized potentials for liquid simulations (OPLS-AA) force field model for n-dodecane. Specifically, the electric dipole moment of TBP, mass density of the mixture, and the excess volume of mixing were computed with TBP mole fraction ranging from 0 to 1. It is found that the aforementioned force field models accurately predict the mass density of the mixture in the entire mole fraction range. Commensurate with experimental measurements, the electric dipole moment of the TBP was found to slightly increase with the mole fraction of TBP in the mixture. Also, in accord with experimental data, the excess volume of mixing is positive in the entire mole fraction range, peaking at TBP mole fraction range 0.3 0.5. Finally, a close examination of the spatial pair correlation functions between TBP molecules, and between TBP and n-dodecane molecules, revealed formation of TBP dimers through self-association at close distance, a phenomenon with ample experimental evidence.

  12. Molecular Dynamics Simulations of the Nucleation of Water: Determining the Sticking Probability and Formation Energy of a Cluster

    E-Print Network [OSTI]

    Kyoko K. Tanaka; Akio Kawano; Hidekazu Tanaka

    2014-02-26T23:59:59.000Z

    We performed molecular dynamics (MD) simulations of the nucleation of water vapor in order to test nucleation theories. Simulations were performed for a wide range of supersaturation ratios (S = 3-25) and water temperatures (Tw=300-390K). We obtained the nucleation rates and the formation free energies of a subcritical cluster from the cluster size distribution. The classical nucleation theory (CNT) and the modified classical nucleation theory (MCNT) overestimate the nucleation rates in all cases. The semi-phenomenological (SP) model, which corrects the MCNT prediction using the second virial coefficient of a vapor, reproduces the formation free energy of a cluster with the size < 20 to within 10 % and the nucleation rate and cluster size distributions to within one order of magnitude. The sticking probability of the vapor molecules to the clusters was also determined from the growth rates of the clusters. The sticking probability rapidly increases with the supersaturation ratio S, which is similar to the Lennard-Jones system.

  13. Distance Restraints from Crosslinking Mass Spectrometry: Mining a Molecular Dynamics Simulation Database to Evaluate Lysine-Lysine Distances

    SciTech Connect (OSTI)

    Merkley, Eric D.; Rysavy, Steven; Kahraman, Abdullah; Hafen, Ryan P.; Daggett, Valerie; Adkins, Joshua N.

    2014-03-18T23:59:59.000Z

    Integrative structural biology models the structures of protein complexes that are intractable by classical structural methods (because of extreme size, dynamics, or heterogeneity) by combining computational structural modeling with data from experimental methods. One such method is chemical cross-linking mass spectrometry (XL-MS), in which cross-linked peptides, derived from a covalently cross-linked protein complex and identified by liquid chromatography-mass spectrometry, pinpoint protein residues close in three-dimensional space. The commonly used lysine-reactive N-hydroxysuccinimide ester reagents disuccinimidylsuberate (DSS) and bis(sulfosuccinimidyl)suberate (BS3) have a linker arm that is 11.4 Å long when fully extended. However, XL-MS studies on proteins of known structure frequently report cross-links that exceed this distance. Typically, a tolerance of ~3 Å is added to the theoretical maximum to account for this observation, with little justification for the value chosen. We used the Dynameomics database, a repository of high-quality molecular dynamics simulations of 807 proteins representative of all protein folds, to investigate the change in lysine-lysine distances resulting from native-state dynamics on the time-scale of tens of nanoseconds. We conclude that observed cross-links are consistent with a protein structure if the distance between cross-linked lysine N? atoms is less than the cross-linker length plus 11.3 Å. For DSS or BS3, this corresponds to a C? to C? distance of 30.4 Å. This analysis provides a theoretical basis for the widespread practice of adding a tolerance to the crosslinker length when comparing XL-MS results to structures, and indicates the appropriate values of an XLMS derived distance constraint to use in structural modeling.

  14. atomistic simulation study: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    14 Simulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine Physics Websites Summary: Simulational nanoengineering: Molecular dynamics...

  15. atomistic simulation studies: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    14 Simulational nanoengineering: Molecular dynamics implementation of an atomistic Stirling engine Physics Websites Summary: Simulational nanoengineering: Molecular dynamics...

  16. Nonstandard Tools for Nonsmooth Analysis

    E-Print Network [OSTI]

    S. S. Kutateladze

    2012-06-11T23:59:59.000Z

    This is an overview of the basic tools of nonsmooth analysis which are grounded on nonstandard models of set theory. By way of illustration we give a criterion for an infinitesimally optimal path of a general discrete dynamic system.

  17. Molecular Simulation of Fracture Dynamics of Symmetric Tilt Grain Boundaries in Graphene

    E-Print Network [OSTI]

    Jhon, Young In; Smith, Robert; Jhon, Myung S

    2012-01-01T23:59:59.000Z

    Atomistic simulations were utilized to obtain microscopic information of the elongation process in graphene sheets consisting of various embedded symmetric tilt grain boundaries (GBs). In contrast to pristine graphene, these GBs fractured in an extraordinary pattern under transverse uniaxial elongation in all but the largest misorientation angle case, which exhibited intermittent crack propagation and formed many stringy residual connections after quasi mechanical failure. The strings known as monoatomic carbon chains (MACCs), whose importance was recently highlighted, gradually extended to a maximum of a few nanometers as the elongation proceeded. These features, which critically affect the tensile stress and the shape of stress-strain curve, were observed in both armchair and zigzag-oriented symmetric tilt GBs. However, there exist remarkable differences in the population density and the achievable length of MACCs appearing after quasi mechanical failure which were higher in the zigzag-oriented GBs. In addi...

  18. Test Cases for Wind Power Plant Dynamic Models on Real-Time Digital Simulator: Preprint

    SciTech Connect (OSTI)

    Singh, M.; Muljadi, E.; Gevorgian, V.

    2012-06-01T23:59:59.000Z

    The objective of this paper is to present test cases for wind turbine generator and wind power plant models commonly used during commissioning of wind power plants to ensure grid integration compatibility. In this paper, different types of wind power plant models based on the Western Electricity Coordinating Council Wind Generator Modeling Group's standardization efforts are implemented on a real-time digital simulator, and different test cases are used to gauge their grid integration capability. The low-voltage ride through and reactive power support capability and limitations of wind turbine generators under different grid conditions are explored. Several types of transient events (e.g., symmetrical and unsymmetrical faults, frequency dips) are included in the test cases. The differences in responses from different types of wind turbine are discussed in detail.

  19. L-H transition dynamics in fluid turbulence simulations with neoclassical force balance

    SciTech Connect (OSTI)

    Chôné, L. [Aix–Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Beyer, P.; Fuhr, G.; Benkadda, S. [Aix–Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Sarazin, Y.; Bourdelle, C. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

    2014-07-15T23:59:59.000Z

    Spontaneous transport barrier generation at the edge of a magnetically confined plasma is reproduced in flux-driven three-dimensional fluid simulations of electrostatic turbulence. Here, the role on the radial electric field of collisional friction between trapped and passing particles is shown to be the key ingredient. Especially, accounting for the self-consistent and precise dependence of the friction term on the actual plasma temperature allows for the triggering of a transport barrier, provided that the input power exceeds some threshold. In addition, the barrier is found to experience quasi-periodic relaxation events, reminiscent of edge localised modes. These results put forward a possible key player, namely, neoclassical physics via radial force balance, for the low- to high-confinement regime transition observed in most of controlled fusion devices.

  20. Energy conserving schemes for the simulation of musical instrument contact dynamics

    E-Print Network [OSTI]

    Chatziioannou, Vasileios

    2015-01-01T23:59:59.000Z

    Collisions are an innate part of the function of many musical instruments. Due to the nonlinear nature of contact forces, special care has to be taken in the construction of numerical schemes for simulation and sound synthesis. Finite difference schemes and other time-stepping algorithms used for musical instrument modelling purposes are normally arrived at by discretising a Newtonian description of the system. However because impact forces are non-analytic functions of the phase space variables, algorithm stability can rarely be established this way. This paper presents a systematic approach to deriving energy conserving schemes for frictionless impact modelling. The proposed numerical formulations follow from discretising Hamilton's equations of motion, generally leading to an implicit system of nonlinear equations that can be solved with Newton's method. The approach is first outlined for point mass collisions and then extended to distributed settings, such as vibrating strings and beams colliding with rig...

  1. Non-contacting transfer of elastic energy into explosive simulants for dynamic property estimation

    SciTech Connect (OSTI)

    Greeney, Nathan S.; Strovink, Kurt M.; Scales, John A. [Physics Department, Colorado School of Mines, Golden, Colorado 80401 (United States); Jessop, Andrew M.; Stuart Bolton, J. [Ray W. Herrick Laboratories, Purdue University, West Lafayette, Indiana 47907-2099 (United States); Watson, Christopher C.; Adams, Douglas E. [Purdue Center for Systems Integrity, Purdue University, Lafayette, Indiana 47905 (United States)

    2014-05-21T23:59:59.000Z

    Non-contacting acoustical methods can be used to extract various material properties of liquid or solid samples without disturbing the sample. These methods are useful even in the lab since they do not involve coupling anything to the sample, which might change its properties. A forteriori, when dealing with potentially dangerous materials, non-contacting methods may be the only safe solutions to mechanical characterization. Here, we show examples of using laser ultrasound to remotely insonify and monitor the elastic properties of several granular explosive simulants. The relatively short near-infrared laser pulse length (a few hundred nanoseconds) provides a broad-band thermoelastic source of ultrasound; we intentionally stay in the thermoelastic regime to avoid damaging the material. Then, we use a scanning laser Doppler vibrometer to measure the ultrasonic response of the sample. LDV technology is well established and very sensitive at ultrasonic frequencies; atomic level motions can be measured with modest averaging. The resulting impulse response of the explosive simulant can be analyzed to determine decay rates and wave speeds, with stiffer samples showing faster wave speeds and lower decay rates. On the other hand, at the low-frequency end of the acoustic spectrum, we use an electronically phased array to couple into a freely suspended sample's normal modes. This allows us to gently heat up the sample (3?°C in just under 5 min, as shown with a thermal IR camera). In addition to the practical interest in making the sample more chemically visible through heat, these two measurements (low-frequency resonant excitation vs high-frequency wave propagation) bracket the frequency range of acoustic non-destructive evaluation methods available.

  2. Goal Tree Success Tree -Dynamic Master Logic Diagram and Monte Carlo Simulation for the Safety and Resilience Assessment of a Multistate System

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    produced by an earthquake and its aftershocks (the external events) on a nuclear power plant (the critical plant) embedded in the connected power and water distribution, and transportation networks which support1 Goal Tree Success Tree - Dynamic Master Logic Diagram and Monte Carlo Simulation for the Safety

  3. The 1st International Symposium on Micro & Nano Technology, 14-17 March, 2004, Honolulu, Hawaii, USA MOLECULAR DYNAMICS SIMULATIONS OF HEAT TRANSFER ISSUES

    E-Print Network [OSTI]

    Maruyama, Shigeo

    , USA MOLECULAR DYNAMICS SIMULATIONS OF HEAT TRANSFER ISSUES IN CARBON NANOTUBES S. Maruyama, Y-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, JAPAN ABSTRACT Several heat transfer problems related to single, and thermal boundary resistance in a junction of nanotubes are reviewed. Then, the heat transfer from an SWNT

  4. Molecular dynamics simulations of hydrogen bombardment of tungsten carbide surfaces P. Trskelin,1 N. Juslin,1 P. Erhart,2 and K. Nordlund1

    E-Print Network [OSTI]

    Nordlund, Kai

    Molecular dynamics simulations of hydrogen bombardment of tungsten carbide surfaces P. Träskelin,1 and tungsten carbide WC is of interest both due to the use of hydrogen-containing plasmas in thin. INTRODUCTION Tungsten carbide WC exhibits extraordinary hardness and temperature resistance. It has long been

  5. Vibrational Sum Frequency Spectroscopy and Molecular Dynamics Simulation of the Carbon Tetrachloride-Water and 1,2-Dichloroethane-Water Interfaces

    E-Print Network [OSTI]

    Richmond, Geraldine L.

    and bonding at the carbon tetrachloride-water (CCl4-H2O) and the 1,2-dichloroethane-water (DCE-H2O) liquidVibrational Sum Frequency Spectroscopy and Molecular Dynamics Simulation of the Carbon Tetrachloride-Water and 1,2-Dichloroethane-Water Interfaces Dave S. Walker, Fred G. Moore, and Geraldine L

  6. Twenty-Seventh Symposium (International) on Combustion/The Combustion Institute, 1998/pp. 22492257 SIMULATION OF THE TRANSIENT, COMPRESSIBLE, GAS-DYNAMIC

    E-Print Network [OSTI]

    Petzold, Linda R.

    ­2257 SIMULATION OF THE TRANSIENT, COMPRESSIBLE, GAS-DYNAMIC BEHAVIOR OF CATALYTIC-COMBUSTION IGNITION2249 Twenty-Seventh Symposium (International) on Combustion/The Combustion Institute, 1998/pp. 2249 combustion in a stagnation-flow configuration. The analysis considers the elementary heterogeneouschem- istry

  7. An integral-balance nonlinear model to simulate changes in soil moisture, groundwater and surface runoff dynamics at the hillslope scale

    E-Print Network [OSTI]

    Jay, Laurent O.

    An integral-balance nonlinear model to simulate changes in soil moisture, groundwater and surface-state integral-balance model for soil moisture and groundwater dynamics. Development of the model was motivated. Ã? 2014 Elsevier Ltd. All rights reserved. 1. Introduction Recent studies on the modeling

  8. Dynamics of the Solar Magnetic Network: Two-dimensional MHD Simulations

    E-Print Network [OSTI]

    S. S. Hasan; A. A. van Ballegoiijen; W. Kalkofen; O. Steiner

    2005-03-24T23:59:59.000Z

    The aim of this work is to identify the physical processes that occur in the network and contribute to its dynamics and heating. We model the network as consisting of individual flux tubes with a non-potential field structure that are located in intergranular lanes. With a typical horizontal size of 200 km at the base of the photosphere, they expand upward and merge with their neighbors at a height of about 600 km. Above a height of approximately 1000 km the magnetic field starts to become uniform. Waves are generated in this medium by means of motions at the lower boundary. We focus on transverse driving, which generates both fast and slow waves within a flux tube and acoustic waves at the interface of the tube and the field-free medium. The acoustic waves at the interface are due to compression of the gas on one side of the flux tube and expansion on the other. These waves travel upward along the two sides of the (2D) flux tube and enter it, where they become longitudinal waves. For impulsive excitation with a time constant of 120 s, we find that a dominant feature is the creation of vortical motions that propagate upward. We have identified an efficient mechanism for the generation of longitudinal waves and shock formation in the chromospheric part of the flux concentration. We examine some broad implications of our results.

  9. A coarse-graining approach for molecular simulation that retains the dynamics of the all-atom reference system by implementing hydrodynamic interactions

    SciTech Connect (OSTI)

    Markutsya, Sergiy [Ames Laboratory; Lamm, Monica H [Ames Laboratory

    2014-11-07T23:59:59.000Z

    We report on a new approach for deriving coarse-grained intermolecular forces that retains the frictional contribution that is often discarded by conventional coarse-graining methods. The approach is tested for water and an aqueous glucose solution, and the results from the new implementation for coarse-grained molecular dynamics simulation show remarkable agreement with the dynamics obtained from reference all-atom simulations. The agreement between the structural properties observed in the coarse-grained and all-atom simulations is also preserved. We discuss how this approach may be applied broadly to any existing coarse-graining method where the coarse-grained models are rigorously derived from all-atom reference systems.

  10. Fluid dynamic studies for a simulated Melton Valley Storage Tank slurry

    SciTech Connect (OSTI)

    Hylton, T.D.; Youngblood, E.L.; Cummins, R.L.

    1994-07-01T23:59:59.000Z

    The Melton Valley Storage Tanks (MVSTs), are used for the collection and storage of remote-handled radioactive liquid wastes. These wastes, which were typically acidic when generated, were neutralized with the addition of sodium hydroxide to protect the storage tanks from corrosion, but this caused the transuranic and heavy metals to precipitate. These wastes will eventually need to be removed from the tanks for ultimate disposal. The objective of the research activities discussed in this report is to support the design of a pipeline transport system between the MVSTs and a treatment facility. Since the wastes in the MVSTs are highly radioactive, a surrogate slurry was developed for this study. Rheological properties of the simulated slurry were determined in a test loop in which the slurry was circulated through three pipeline viscometers of different diameters. Pressure drop data at varying flow rates were used to obtain shear stress and shear rate data. The data were analyzed, and the slurry rheological properties were analyzed by the Power Law model and the Bingham plastic model. The plastic viscosity and yield stress data obtained from the rheological tests were used as inputs for a piping design software package, and the pressure drops predicted by the software compared well with the pressure drop data obtained from the test loop. The minimum transport velocity was determine for the slurry by adding known nominal sizes of glass spheres to the slurry. However, it was shown that the surrogate slurry exhibited hindered settling, which may substantially decrease the minimum transport velocity. Therefore, it may be desired to perform additional tests with a surrogate with a lower concentration of suspended solids to determine the minimum transport velocity.

  11. Validation of a Building Simulation Tool Using Field Data for Three Identical Configuration Full-Serve Restaurants Using Different HVAC Systems

    E-Print Network [OSTI]

    Brillhart, P. L.; Worek, W. M.

    2000-01-01T23:59:59.000Z

    A new building application for a pre-existing HVAC software tool which calculates the benefits of desiccant-assisted HVAC equipment versus the performance of a standard vapor-compression system is used to model the monitored results, see Yborra...

  12. Using HLA and Grid for Distributed Multiscale Simulations

    E-Print Network [OSTI]

    Amsterdam, Universiteit van

    ) and hydro dynamics (simulation of collisions - in micro scale). Combining simulations of different scale

  13. Benchmark of the IMPACT Code for High Intensity Beam DynamicsSimulation

    SciTech Connect (OSTI)

    Qiang, J.; Ryne, R.D.

    2006-11-16T23:59:59.000Z

    The IMPACT (Integrated Map and Particle Accelerator Tracking) code was first developed under Computational Grand Challenge project in the mid 1990s [1]. It started as a three-dimensional (3D) data parallel particle-in-cell (PIC) code written in High Performance Fortran. The code used a split-operator based method to solve the Hamiltonian equations of motion. It contained linear transfer maps for drifts, quadrupole magnets and rf cavities. The space-charge forces were calculated using an FFT-based method with 3D open boundary conditions and longitudinal periodic boundary conditions. This code was completely rewritten in the late 1990s based on a message passing parallel programming paradigm using Fortran 90 and MPI following an object-oriented software design. This improved the code's scalability on large parallel computer systems and also gave the code better software maintainability and extensibility [2]. In the following years, under the SciDAC-1 accelerator project, the code was extended to include more accelerating and focusing elements such as DTL, CCL, superconducting linac, solenoid, dipole, multipoles, and others. Besides the original split-operator based integrator, a direct integration of Lorentz equations of motion using a leap-frog algorithm was also added to the IMPACT code to handle arbitrary external nonlinear fields. This integrator can read in 3D electromagnetic fields in a Cartesian grid or in a cylindrical coordinate system. Using the Lorentz integrator, we also extended the original code to handle multiple charge-state beams. The space-charge solvers were also extended to include conducting wall effects for round and rectangular pipes with longitudinal open and periodic boundary conditions. Recently, it has also been extended to handle short-range wake fields (longitudinal monopole and transverse dipole) and longitudinal coherent synchrotron radiation wake fields. Besides the parallel macroparticle tracking code, an rf linac lattice design code, an envelope matching and analysis code, and a number of pre- and post-processing codes were also developed to form the IMPACT code suite. The IMPACT code suite has been used to study beam dynamics in the SNS linac, the J-PARC linac commissioning, the CERN superconducting linac design, the Los Alamos Low Energy Demonstration Accelerator (LEDA) halo experiment, the Rare Isotope Accelerator (RIA) driver linac design, and the FERMI{at}Elettra FEL linac design [3-8]. It has also been used to study space-charge resonance in anisotropic beams [9-11].

  14. Decision-making through performance simulation and code compliance from the early, schematic phases of building design

    E-Print Network [OSTI]

    and external temperature variations and a utilization factor of the dynamic effect of internal and solar heat (just like performance simulation tools) are mostly used at the end of the building design process that acts as a data manager and process controller to allow concurrent use of #12;2 multiple simulation

  15. Workflow Tools

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    at NERSC go here. Galaxy - Galaxy is a web based workflow tool that is use by the genomics community. It allows you to define job dependencies via a web based workflow engine....

  16. Queer Tools

    E-Print Network [OSTI]

    Hacker, Randi; Tsutsui, William

    2007-11-19T23:59:59.000Z

    Broadcast Transcript: Chindogu. Did someone say "Bless you?" No need. This is a Japanese word that means "queer tools" and it was coined to describe the Japanese penchant for unusual inventions. From toilet paper rolls that attach to the head...

  17. SLUG -- Stochastically Lighting Up Galaxies. III: A Suite of Tools for Simulated Photometry, Spectroscopy, and Bayesian Inference with Stochastic Stellar Populations

    E-Print Network [OSTI]

    Krumholz, Mark R; da Silva, Robert L; Rendahl, Theodore; Parra, Jonathan

    2015-01-01T23:59:59.000Z

    Stellar population synthesis techniques for predicting the observable light emitted by a stellar population have extensive applications in numerous areas of astronomy. However, accurate predictions for small populations of young stars, such as those found in individual star clusters, star-forming dwarf galaxies, and small segments of spiral galaxies, require that the population be treated stochastically. Conversely, accurate deductions of the properties of such objects also requires consideration of stochasticity. Here we describe a comprehensive suite of modular, open-source software tools for tackling these related problems. These include: a greatly-enhanced version of the slug code introduced by da Silva et al. (2012), which computes spectra and photometry for stochastically- or deterministically-sampled stellar populations with nearly-arbitrary star formation histories, clustering properties, and initial mass functions; cloudy_slug, a tool that automatically couples slug-computed spectra with the cloudy r...

  18. CANCELLED Molecular dynamics simulations of noble gases in liquidwater: Solvati on structure, self-diffusion, and kinetic isotopeeffect

    SciTech Connect (OSTI)

    Bourg, I.C.; Sposito, G.

    2007-05-25T23:59:59.000Z

    Despite their great importance in low-temperaturegeochemistry, self-diffusion coefficients of noble gas isotopes in liquidwater (D) have been measured only for the major isotopes of helium, neon,krypton and xenon. Data on the self-diffusion coefficients of minor noblegas isotopes are essentially non-existent and so typically are estimatedby a kinetic theory model in which D varies as the inverse square root ofthe isotopic mass (m): D proportional to m-0.5. To examine the validityof the kinetic theory model, we performed molecular dynamics (MD)simulations of the diffusion of noble gases in ambient liquid water withan accurate set of noble gas-water interaction potentials. Our simulationresults agree with available experimental data on the solvation structureand self-diffusion coefficients of the major noble gas isotopes in liquidwater and reveal for the first time that the isotopic mass-dependence ofall noble gas self-diffusion coefficients has the power-law form Dproportional to m-beta with 0

  19. Coordination and Hydrolysis of Plutonium Ions in Aqueous Solution using Car-Parrinello Molecular Dynamics Free Energy Simulations

    SciTech Connect (OSTI)

    Odoh, Samuel O.; Bylaska, Eric J.; De Jong, Wibe A.

    2013-11-27T23:59:59.000Z

    Car-Parrinello molecular dynamics (CPMD) simulations have been used to examine the hydration structures, coordination energetics and the first hydrolysis constants of Pu3+, Pu4+, PuO2+ and PuO22+ ions in aqueous solution at 300 K. The coordination numbers and structural properties of the first shell of these ions are in good agreement with available experimental estimates. The hexavalent PuO22+ species is coordinated to 5 aquo ligands while the pentavalent PuO2+ complex is coordinated to 4 aquo ligands. The Pu3+ and Pu4+ ions are both coordinated to 8 water molecules. The first hydrolysis constants obtained for Pu3+ and PuO22+ are 6.65 and 5.70 respectively, all within 0.3 pH units of the experimental values (6.90 and 5.50 respectively). The hydrolysis constant of Pu4+, 0.17, disagrees with the value of -0.60 in the most recent update of the Nuclear Energy Agency Thermochemical Database (NEA-TDB) but supports recent experimental findings. The hydrolysis constant of PuO2+, 9.51, supports the experimental results of Bennett et al. (Radiochim. Act. 1992, 56, 15). A correlation between the pKa of the first hydrolysis reaction and the effective charge of the plutonium center was found.

  20. Force and heat current formulas for many-body potentials in molecular dynamics simulation with applications to thermal conductivity calculations

    E-Print Network [OSTI]

    Fan, Zheyong; Wang, Hui-Qiong; Zheng, Jin-Cheng; Donadio, Davide; Harju, Ari

    2015-01-01T23:59:59.000Z

    We derive expressions of interatomic force and heat current for many-body potentials such as the Tersoff, the Brenner, and the Stillinger-Weber potential used extensively in molecular dynamics simulations of covalently bonded materials. Although these potentials have a many-body nature, a pairwise force expression that follows Newton's third law can be found without referring to any partition of the potential. Based on this force formula, a stress applicable for periodic systems can be unambiguously defined. The force formula can then be used to derive the heat current formulas using a natural potential partitioning. Our heat current formulation is found to be equivalent to most of the seemingly different heat current formulas used in the literature, but to deviate from the stress-based formula derived from two-body potential. We validate our formulation numerically on various systems descried by the Tersoff potential, namely three-dimensional silicon and diamond, two-dimensional graphene, and quasi-one-dimen...

  1. The BlueDRAGON -A System for Measuring the Kinematics and the Dynamics of Minimally Invasive Surgical Tools InVivo

    E-Print Network [OSTI]

    tools' kinematics necessary to conduct an operation. This is especially problematic in the field of MIS where the teacher is one step removed from the actual conduct of the operation. Along with the progress

  2. Andy H. F. Chow, G. Gomes, A.A. Kurzhanskiy, and P. Varaiya 1 AURORA RNM A MACROSCOPIC SIMULATION TOOL FOR ARTERIAL2

    E-Print Network [OSTI]

    Varaiya, Pravin

    Andy H. F. Chow, G. Gomes, A.A. Kurzhanskiy, and P. Varaiya 1 1 AURORA RNM ­ A MACROSCOPIC model for urban signal control based on the3 Aurora Road Network Modeler (RNM) software package an extension of the Aurora-RNM traffic simulator from freeways to3 arterial networks developed under the TOPL

  3. Java Vertexing Tools

    SciTech Connect (OSTI)

    Strube, Jan; /Oregon U.; Graf, Norman; /SLAC

    2006-03-03T23:59:59.000Z

    This document describes the implementation of the topological vertex finding algorithm ZVTOP within the org.lcsim reconstruction and analysis framework. At the present date, Java vertexing tools allow users to perform topological vertexing on tracks that have been obtained from a Fast MC simulation. An implementation that will be able to handle fully reconstructed events is being designed from the ground up for longevity and maintainability.

  4. High performance distributed simulation for interactive simulated vascular reconstruction

    E-Print Network [OSTI]

    Amsterdam, Universiteit van

    performance. 1 Introduction Interactive simulation environments are dynamic systems that combine simula- tion.1 Performance of interactive simulation environments The most important factor in the performance of a dynamic dynamic simulation environment. 1 1 2 2 3 visualization rendering simulation time rendering delay

  5. Better IAQ through integrating design tools for the HVACindustry

    SciTech Connect (OSTI)

    Laine, Tuomas; Kosonen, Risto; Hagstrom, Kim; Mustakallio, Panu; Yin, De-Wei; Haves, Philip; Chen, Qingyan

    2000-06-01T23:59:59.000Z

    There is currently no effective combination of interoperable design tools to cover all critical aspects of the HVAC design process. Existing design tools are separately available, but require expertise and operating time that is beyond the scope of a normal design project. For example, energy analysis and computational fluid dynamics (CFD) tools are not used in practical design, leading to poor indoor air quality and/or unnecessary energy consumption in buildings. A prototype integrated software tool for demonstration, process mapping and proof-of-concept purposes was developed under a new international, Finland/USA jointly funded development project BildIT. Individual design tools were simplified and adapted to specific applications and also integrated so that they can be used in a timely and effective manner by the designer. The core of the prototype linked together an architectural CAD system, a 3D space model, a CFD program and a building energy simulation program and it utilizes real product data from manufacturer's software. Also the complex building design, construction, maintenance and retrofit processes were mapped to get a template for the structure of the integrated design tool.

  6. Developing a risk management "flight simulator" for manned space programs : a user interface to a system dynamic simulation of system safety at NASA

    E-Print Network [OSTI]

    Friedenthal, Stephen R. (Stephen Roger)

    2006-01-01T23:59:59.000Z

    Simulators are a staple of any engineering project and manned space flight in particular. From pilot and crew training to maintenance and emergency repairs, very little is done without it first being thoroughly practiced ...

  7. Ootw Tool Requirements in Relation to JWARS

    SciTech Connect (OSTI)

    Hartley III, D.S.; Packard, S.L.

    1998-01-01T23:59:59.000Z

    This document reports the results of the CMke of the Secretary of Defense/Program Analysis & Evaluation (OSD/PA&E) sponsored project to identify how Operations Other Than War (OOTW) tool requirements relate to the Joint Warfare Simulation (JWARS) and, more generally, to joint analytical modeling and simulation (M&S) requirements. It includes recommendations about which OOTW tools (and functionality within tools) should be included in JWARS, which should be managed as joint analytical modeling and simulation (M&S) tools, and which should be left for independent development.

  8. A one-dimensional sectional model to simulate multicomponent aerosol dynamics in the marine boundary layer 1. Model description

    SciTech Connect (OSTI)

    Fitzgerald, J.W.; Hoppel, W.A. [Remote Sensing Division, Naval Research Laboratory, Washington, District of Columbia (United States)] [Remote Sensing Division, Naval Research Laboratory, Washington, District of Columbia (United States); Gelbard, F. [Modeling and Analysis Department, Sandia National Laboratories, Albuquerque, New Mexico (United States)] [Modeling and Analysis Department, Sandia National Laboratories, Albuquerque, New Mexico (United States)

    1998-07-01T23:59:59.000Z

    A one-dimensional, multicomponent sectional model has been developed to simulate the temporal and vertical variations of the aerosol size distribution and composition in the marine boundary layer (MBL). An important aspect of the model is its ability to handle the transport of aerosols in an atmosphere with humidity gradients with no numerical diffusion caused by the swelling and shrinking of the particles as they move through the humidity gradients. This is achieved by rewriting the aerosol general dynamical equation (GDE) in terms of dry radius thus transferring all variations in radius caused by temporal and spatial humidity variations to the rate coefficients appearing in the equations. The model then solves the new GDE in fixed dry size sections, with the humidity dependence of the processes now included in variable coefficients. This procedure also results in correct gradient transport. A limiting assumption is that the particles equilibrate instantaneously with the ambient water vapor. This assumption limits the maximum particle size which can be treated in the model to ambient (wet) radii less than about 30 {mu}m. All processes currently believed to be important in shaping the MBL size distribution are included in the current version of the model. These include generation of sea-salt aerosol at the ocean surface, nucleation of new particles, coagulation, growth due to condensation of gas-phase reaction products, growth due to sulfate formation during cloud processing, precipitation scavenging, surface deposition, turbulent mixing, gravitational settling, and exchange with the free troposphere. Simple gas-phase chemistry which includes the oxidation of dimethylsulfide and SO{sub 2} to sulfate is incorporated in the current version of the model. {copyright} 1998 American Geophysical Union

  9. Chaos in plasma simulation and experiment

    SciTech Connect (OSTI)

    Watts, C. [Texas Univ., Austin, TX (United States). Fusion Research Center; Newman, D.E. [Oak Ridge National Lab., TN (United States); Sprott, J.C. [Wisconsin Univ., Madison, WI (United States). Plasma Physics Research

    1993-09-01T23:59:59.000Z

    We investigate the possibility that chaos and simple determinism are governing the dynamics of reversed field pinch (RFP) plasmas using data from both numerical simulations and experiment. A large repertoire of nonlinear analysis techniques is used to identify low dimensional chaos. These tools include phase portraits and Poincard sections, correlation dimension, the spectrum of Lyapunov exponents and short term predictability. In addition, nonlinear noise reduction techniques are applied to the experimental data in an attempt to extract any underlying deterministic dynamics. Two model systems are used to simulate the plasma dynamics. These are -the DEBS code, which models global RFP dynamics, and the dissipative trapped electron mode (DTEM) model, which models drift wave turbulence. Data from both simulations show strong indications of low,dimensional chaos and simple determinism. Experimental data were obtained from the Madison Symmetric Torus RFP and consist of a wide array of both global and local diagnostic signals. None of the signals shows any indication of low dimensional chaos or other simple determinism. Moreover, most of the analysis tools indicate the experimental system is very high dimensional with properties similar to noise. Nonlinear noise reduction is unsuccessful at extracting an underlying deterministic system.

  10. Numerical simulations of epitaxial growth process in MOVPE reactor as a tool for design of modern semiconductors for high power electronics

    SciTech Connect (OSTI)

    Skibinski, Jakub; Wejrzanowski, Tomasz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska 141, 02507 Warsaw (Poland); Caban, Piotr [Institute of Electronic Materials Technology, Wolczynska 133, 01919 Warsaw (Poland); Kurzydlowski, Krzysztof J. [Warsaw University of Technology, Faculty of Materials Science and Engineering Woloska, 141, 02507 Warsaw (Poland)

    2014-10-06T23:59:59.000Z

    In the present study numerical simulations of epitaxial growth of gallium nitride in Metal Organic Vapor Phase Epitaxy reactor AIX-200/4RF-S is addressed. Epitaxial growth means crystal growth that progresses while inheriting the laminar structure and the orientation of substrate crystals. One of the technological problems is to obtain homogeneous growth rate over the main deposit area. Since there are many agents influencing reaction on crystal area such as temperature, pressure, gas flow or reactor geometry, it is difficult to design optimal process. According to the fact that it's impossible to determine experimentally the exact distribution of heat and mass transfer inside the reactor during crystal growth, modeling is the only solution to understand the process precisely. Numerical simulations allow to understand the epitaxial process by calculation of heat and mass transfer distribution during growth of gallium nitride. Including chemical reactions in numerical model allows to calculate the growth rate of the substrate and estimate the optimal process conditions for obtaining the most homogeneous product.

  11. Household Response To Dynamic Pricing Of Electricity: A Survey...

    Open Energy Info (EERE)

    Household Response To Dynamic Pricing Of Electricity: A Survey Of The Experimental Evidence Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Household Response To Dynamic...

  12. The Open Source Stochastic Building Simulation Tool SLBM and Its Capabilities to Capture Uncertainty of Policymaking in the U.S. Building Sector

    SciTech Connect (OSTI)

    Stadler, Michael; Marnay, Chris; Azevedo, Ines Lima; Komiyama, Ryoichi; Lai, Judy

    2009-05-14T23:59:59.000Z

    The increasing concern about climate change as well as the expected direct environmental economic impacts of global warming will put considerable constraints on the US building sector, which consumes roughly 48percent of the total primary energy, making it the biggest single source of CO2 emissions. It is obvious that the battle against climate change can only be won by considering innovative building approaches and consumer behaviors and bringing new, effective low carbon technologies to the building / consumer market. However, the limited time given to mitigate climate change is unforgiving to misled research and / or policy. This is the reason why Lawrence Berkeley National Lab is working on an open source long range Stochastic Lite Building Module (SLBM) to estimate the impact of different policies and consumer behavior on the market penetration of low carbon building technologies. SLBM is designed to be a fast running, user-friendly model that analysts can readily run and modify in its entirety through a visual interface. The tool is fundamentally an engineering-economic model with technology adoption decisions based on cost and energy performance characteristics of competing technologies. It also incorporates consumer preferences and passive building systems as well as interactions between technologies (such as internal heat gains). Furthermore, everything is based on service demand, e.g. a certain temperature or luminous intensity, instead of energy intensities. The core objectives of this paper are to demonstrate the practical approach used, to start a discussion process between relevant stakeholders and to build collaborations.

  13. Dynamic Simulation Studies of the Frequency Response of the Three U.S. Interconnections with Increased Wind Generation

    E-Print Network [OSTI]

    Mackin, Peter

    2011-01-01T23:59:59.000Z

    North America Dynamic Wind Generator Modeling Update, Basedperformed by the WECC Wind Generator Modeling Group and theTo model the interactions between wind generators and the

  14. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    SciTech Connect (OSTI)

    Tilocca, Antonio [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)] [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2013-09-21T23:59:59.000Z

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ?10{sup 3} atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their application in different fields. In addition, as a first application of the present findings, the fully converged structure of the 45S5 glass was further analyzed to shed new light on several dissolution-related features whose interpretation has been rather controversial in the past.

  15. Development of an electron-temperature-dependent interatomic potential for molecular dynamics simulation of tungsten under electronic excitation

    E-Print Network [OSTI]

    Alfè, Dario

    simulation of tungsten under electronic excitation S. Khakshouri,1,* D. Alfè,1,2 and D. M. Duffy1,3 1

  16. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry: Spray Simulations

    SciTech Connect (OSTI)

    Rutland, Christopher J.

    2009-04-26T23:59:59.000Z

    The Terascale High-Fidelity Simulations of Turbulent Combustion (TSTC) project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of the approach is direct numerical simulation (DNS) featuring the highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. Under this component of the TSTC program the simulation code named S3D, developed and shared with coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for turbulent liquid fuel spray dynamics. Major accomplishments include improved fundamental understanding of mixing and auto-ignition in multi-phase turbulent reactant mixtures and turbulent fuel injection spray jets.

  17. 19th. AIAA-CEAS Aeroacoutics Conference, May 28th 2013, Berlin Dynamic Modeling and Numerical Simulation of

    E-Print Network [OSTI]

    Huang, Xun

    19th. AIAA-CEAS Aeroacoutics Conference, May 28th 2013, Berlin Dynamic Modeling and Numerical was presented in this paper. By this control-oriented model, transient dynamic process of multi-physics coupling problem in a progressive wave tube could be approximately studied. The proposed model is verified

  18. Research Tools

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert Southwest RegionatSearch Welcome toResearch Areas OurLANLSoftware & Tools

  19. Tools | JCESR

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert Southwest RegionatSearchScheduled System BurstLongTitan Titan is a two-beamTools JCESR

  20. Enrollment Tools

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-Series toESnet4: Networking for37EnergyNuclear SecurityEnolEnrollment Tools