WorldWideScience

Sample records for model simulations electronic

  1. Teaching Behavioral Modeling and Simulation Techniques for Power Electronics Courses

    Science.gov (United States)

    Abramovitz, A.

    2011-01-01

    This paper suggests a pedagogical approach to teaching the subject of behavioral modeling of switch-mode power electronics systems through simulation by general-purpose electronic circuit simulators. The methodology is oriented toward electrical engineering (EE) students at the undergraduate level, enrolled in courses such as "Power…

  2. Simulation model for electron irradiated IGZO thin film transistors

    Science.gov (United States)

    Dayananda, G. K.; Shantharama Rai, C.; Jayarama, A.; Kim, Hyun Jae

    2018-02-01

    An efficient drain current simulation model for the electron irradiation effect on the electrical parameters of amorphous In-Ga-Zn-O (IGZO) thin-film transistors is developed. The model is developed based on the specifications such as gate capacitance, channel length, channel width, flat band voltage etc. Electrical parameters of un-irradiated IGZO samples were simulated and compared with the experimental parameters and 1 kGy electron irradiated parameters. The effect of electron irradiation on the IGZO sample was analysed by developing a mathematical model.

  3. Transverse Momentum Distributions of Electron in Simulated QED Model

    Science.gov (United States)

    Kaur, Navdeep; Dahiya, Harleen

    2018-05-01

    In the present work, we have studied the transverse momentum distributions (TMDs) for the electron in simulated QED model. We have used the overlap representation of light-front wave functions where the spin-1/2 relativistic composite system consists of spin-1/2 fermion and spin-1 vector boson. The results have been obtained for T-even TMDs in transverse momentum plane for fixed value of longitudinal momentum fraction x.

  4. Probabilistic model for the simulation of secondary electron emission

    Directory of Open Access Journals (Sweden)

    M. A. Furman

    2002-12-01

    Full Text Available We provide a detailed description of a model and its computational algorithm for the secondary electron emission process. The model is based on a broad phenomenological fit to data for the secondary-emission yield and the emitted-energy spectrum. We provide two sets of values for the parameters by fitting our model to two particular data sets, one for copper and the other one for stainless steel.

  5. Modeling a Miniaturized Scanning Electron Microscope Focusing Column - Lessons Learned in Electron Optics Simulation

    Science.gov (United States)

    Loyd, Jody; Gregory, Don; Gaskin, Jessica

    2016-01-01

    /Fourier series hybrid approach. The presentation will give background remarks about the MSFC mini Lunar SEM concept and electron optics modeling, followed by a description of the alternate field modeling techniques that were tried, along with their incorporation into a ray-trace simulation. Next, the validation of this simulation against commercially available software will be discussed using an example lens as a test case. Then, the efficacy of aberration assessment using direct ray-tracing will be demonstrated, using this same validation case. The discussion will include practical error checks of the field solution. Finally, the ray-trace assessment of the MSFC mini Lunar SEM concept will be shown and discussed. The authors believe this presentation will be of general interest to practitioners of modeling and simulation, as well as those with a general optics background. Because electron optics and photon optics share many basic concepts (e.g., lenses, images, aberrations, etc.), the appeal of this presentation need not be restricted to just those interested in charged particle optics.

  6. Modeling and Simulation for the Investigation of Radar Responses to Electronic Attacks in Electronic Warfare Environments

    Directory of Open Access Journals (Sweden)

    So Ryoung Park

    2018-01-01

    Full Text Available An electronic warfare (EW simulator is presented to investigate and evaluate the tracking performance of radar system under the electronic attack situations. The EW simulator has the input section in which the characteristic parameters of radar threat, radar warning receiver, jammer, electromagnetic wave propagation, and simulation scenario can be set up. During the process of simulation, the simulator displays the situations of simulation such as the received signal and its spectrum, radar scope, and angle tracking scope and also calculates the transient and root-mean-squared tracking errors of the range and angle tracking system of radar. Using the proposed EW simulator, we analyze the effect of concealment according to the noise and signal powers under the noise jamming and also analyze the effect of deception by calculating errors between the desired value and the estimated one under the deceptive jamming. Furthermore, the proposed EW simulator can be used to figure out the feature of radar threats based on the information collected from the EW receiver and also used to carry out the electronic attacks efficiently in electronic warfare.

  7. Modeling and Simulation of DC Power Electronics Systems Using Harmonic State Space (HSS) Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2015-01-01

    based on the state-space averaging and generalized averaging, these also have limitations to show the same results as with the non-linear time domain simulations. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling......For the efficiency and simplicity of electric systems, the dc based power electronics systems are widely used in variety applications such as electric vehicles, ships, aircrafts and also in homes. In these systems, there could be a number of dynamic interactions between loads and other dc-dc....... Through this method, the required computation time and CPU memory for large dc power electronics systems can be reduced. Besides, the achieved results show the same results as with the non-linear time domain simulation, but with the faster simulation time which is beneficial in a large network....

  8. Multi-scale modelling and numerical simulation of electronic kinetic transport

    International Nuclear Information System (INIS)

    Duclous, R.

    2009-11-01

    This research thesis which is at the interface between numerical analysis, plasma physics and applied mathematics, deals with the kinetic modelling and numerical simulations of the electron energy transport and deposition in laser-produced plasmas, having in view the processes of fuel assembly to temperature and density conditions necessary to ignite fusion reactions. After a brief review of the processes at play in the collisional kinetic theory of plasmas, with a focus on basic models and methods to implement, couple and validate them, the author focuses on the collective aspect related to the free-streaming electron transport equation in the non-relativistic limit as well as in the relativistic regime. He discusses the numerical development and analysis of the scheme for the Vlasov-Maxwell system, and the selection of a validation procedure and numerical tests. Then, he investigates more specific aspects of the collective transport: the multi-specie transport, submitted to phase-space discontinuities. Dealing with the multi-scale physics of electron transport with collision source terms, he validates the accuracy of a fast Monte Carlo multi-grid solver for the Fokker-Planck-Landau electron-electron collision operator. He reports realistic simulations for the kinetic electron transport in the frame of the shock ignition scheme, the development and validation of a reduced electron transport angular model. He finally explores the relative importance of the processes involving electron-electron collisions at high energy by means a multi-scale reduced model with relativistic Boltzmann terms

  9. Modelling and Simulation of a Synchronous Machine with Power Electronic Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    is modelled in SIMULINK as well. The resulting model can more accurately represent non-idea situations such as non-symmetrical parameters of the electrical machines and unbalance conditions. The model may be used for both steady state and large-signal dynamic analysis. This is particularly useful......This paper reports the modeling and simulation of a synchronous machine with a power electronic interface in direct phase model. The implementation of a direct phase model of synchronous machines in MATLAB/SIMULINK is presented .The power electronic system associated with the synchronous machine...... in the systems where a detailed study is needed in order to assess the overall system stability. Simulation studies are performed under various operation conditions. It is shown that the developed model could be used for studies of various applications of synchronous machines such as in renewable and DG...

  10. Tabulated square-shaped source model for linear accelerator electron beam simulation.

    Science.gov (United States)

    Khaledi, Navid; Aghamiri, Mahmood Reza; Aslian, Hossein; Ameri, Ahmad

    2017-01-01

    Using this source model, the Monte Carlo (MC) computation becomes much faster for electron beams. The aim of this study was to present a source model that makes linear accelerator (LINAC) electron beam geometry simulation less complex. In this study, a tabulated square-shaped source with transversal and axial distribution biasing and semi-Gaussian spectrum was investigated. A low energy photon spectrum was added to the semi-Gaussian beam to correct the bremsstrahlung X-ray contamination. After running the MC code multiple times and optimizing all spectrums for four electron energies in three different medical LINACs (Elekta, Siemens, and Varian), the characteristics of a beam passing through a 10 cm × 10 cm applicator were obtained. The percentage depth dose and dose profiles at two different depths were measured and simulated. The maximum difference between simulated and measured percentage of depth doses and dose profiles was 1.8% and 4%, respectively. The low energy electron and photon spectrum and the Gaussian spectrum peak energy and associated full width at half of maximum and transversal distribution weightings were obtained for each electron beam. The proposed method yielded a maximum computation time 702 times faster than a complete head simulation. Our study demonstrates that there was an excellent agreement between the results of our proposed model and measured data; furthermore, an optimum calculation speed was achieved because there was no need to define geometry and materials in the LINAC head.

  11. In-the-loop simulation of electronic automatic temperature control systems: HVAC modeling

    Energy Technology Data Exchange (ETDEWEB)

    Domschke, R.; Matthes, M. [Visteon Deutschland GmbH, Kerpen (Germany)

    2006-07-01

    The Electronic Automatic Temperature Control (EATC) ensures the occupant comfort and provides safety features like rapid defrost and demist protection. Doing this, the EATC controller provides a direct interface to the end consumer and has a considerable impact on customer satisfaction. The In-the-loop (IL) simulation process is an integral part of Visteons model-based development process. It helps to design and calibrate the EATC controller. It consists of several IL simulation techniques like Model-in-the-loop (MIL), Software-in-the-loop (SIL) and Hardware-in-the-loop (HIL). In this article, we will focus on MIL/SIL Simulations. MIL/SIL allows simulation of the EATC controller in a virtual vehicle environment from the early states of and throughout the development process. This ensures a rapid, high quality and robust development process. The MIL/SIL model contains a thermal vehicle model, a heating, ventilation and air conditioning (HVAC) unit model and a model of the EATC controller itself. The thermal vehicle model simulates transient temperature and humidity conditions in the passenger compartment of a vehicle, settings from the controller, heat fluxes through the vehicle shell and windows, solar load and several further boundary conditions. Whereas the thermal vehicle model of a specific vehicle can be adapted from a default data base, one has to pay special attention to the HVAC unit model. Visteon has developed a special, physically based HVAC unit model to be adapted and implemented into the MIL/SIL simulation. This HVAC model enables a straightforward implementation of different HVAC architectures into the MIL/SIL simulation. Moreover, changes in the HVAC settings (i.e. different blower/scroll assemblies) can be assessed and the influence on passenger comfort can be quantified. Examples of the MIL/SIL simulation demonstrate the benefits of this approach. Results are discussed and a further outlook provided. (orig.)

  12. Frequency Domain Modeling and Simulation of DC Power Electronic Systems Using Harmonic State Space Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    For the efficiency and simplicity of electric systems, the dc power electronic systems are widely used in a variety of applications such as electric vehicles, ships, aircraft and also in homes. In these systems, there could be a number of dynamic interactions and frequency coupling between network...... with different switching frequency or harmonics from ac-dc converters makes that harmonics and frequency coupling are both problems of ac system and challenges of dc system. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling...

  13. Application of new simulation algorithms for modeling rf diagnostics of electron clouds

    International Nuclear Information System (INIS)

    Veitzer, Seth A.; Smithe, David N.; Stoltz, Peter H.

    2012-01-01

    Traveling wave rf diagnostics of electron cloud build-up show promise as a non-destructive technique for measuring plasma density and the efficacy of mitigation techniques. However, it is very difficult to derive an absolute measure of plasma density from experimental measurements for a variety of technical reasons. Detailed numerical simulations are vital in order to understand experimental data, and have successfully modeled build-up. Such simulations are limited in their ability to reproduce experimental data due to the large separation of scales inherent to the problem. Namely, one must resolve both rf frequencies in the GHz range, as well as the plasma modulation frequency of tens of MHz, while running for very long simulations times, on the order of microseconds. The application of new numerical simulation techniques allow us to bridge the simulation scales in this problem and produce spectra that can be directly compared to experiments. The first method is to use a plasma dielectric model to measure plasma-induced phase shifts in the rf wave. The dielectric is modulated at a low frequency, simulating the effects of multiple bunch crossings. This allows simulations to be performed without kinetic particles representing the plasma, which both speeds up the simulations as well as reduces numerical noise from interpolation of particle charge and currents onto the computational grid. Secondly we utilize a port boundary condition model to simultaneously absorb rf at the simulation boundaries, and to launch the rf into the simulation. This method improves the accuracy of simulations by restricting rf frequencies better than adding an external (finite) current source to drive rf, and absorbing layers at the boundaries. We also explore the effects of non-uniform plasma densities on the simulated spectra.

  14. Nonlinear simulation of magnetic reconnection with a drift kinetic electron model

    International Nuclear Information System (INIS)

    Zwingmann, W.; Ottaviani, M.

    2004-01-01

    The process of reconnection allows for a change of magnetic topology inside a plasma. It is an important process for eruptive phenomena in astrophysical plasma, and the sawtooth relaxation in laboratory plasma close to thermonuclear conditions. The sawtooth relaxation is associated with the collisionless electron tearing instability, caused by the electron inertia. A thorough treatment therefore requires a kinetic model for the electron dynamics. In this contribution, we report on the numerical simulation of the electron tearing instability by solving the Vlasov equation directly. The results confirm results of an early paper on the same subject, and extends them to smaller values of the collision skin depth d e = 0.25. Our results suggest a faster than exponential growth in the early nonlinear phase of the instability. We observe as well an asymmetry of the resulting fields. It seems, however, that the field structure becomes closer to the fluid case for small values of d e

  15. Development of Electronic Load Controllers for Free-Piston Stirling Convertors Aided by Stirling Simulation Model

    Science.gov (United States)

    Regan, Timothy F.

    2004-01-01

    The free-piston Stirling convertor end-to-end modeling effort at the NASA Glenn Research Center has produced a software-based test bed in which free-piston Stirling convertors can be simulated and evaluated. The simulation model includes all the components of the convertor: the Stirling cycle engine, heat source, linear alternator, controller, and load. So far, it has been used in evaluating the performance of electronic controller designs. Three different controller design concepts were simulated using the model: 1) Controllers with parasitic direct current loading. 2) Controllers with parasitic alternating current loading. 3) Controllers that maintain a reference current. The free-piston Stirling convertor is an electromechanical device that operates at resonance. It is the function of the electronic load controller to ensure that the electrical load seen by the machine is always great enough to keep the amplitude of the piston and alternator oscillation at the rated value. This is done by regulating the load on the output bus. The controller monitors the instantaneous voltage, regulating it by switching loads called parasitic loads onto the bus whenever the bus voltage is too high and removing them whenever the voltage is too low. In the first type of controller, the monitor-ing and switching are done on the direct-current (dc) bus. In the second type, the alternating current bus is used. The model allows designers to test a controller concept before investing time in hardware. The simulation code used to develop the model also offers detailed models of digital and analog electronic components so that the resulting designs are realistic enough to translate directly into hardware circuits.

  16. Simulation of a Rapid Dropout Event for Highly Relativistic Electrons with the RBE Model

    Science.gov (United States)

    Kang, S-B.; Fok, M.-C.; Glocer, A.; Min, K.-W.; Choi, C.-R.; Choi, E.; Hwang, J.

    2016-01-01

    A flux dropout is a sudden and sizable decrease in the energetic electron population of the outer radiation belt on the time scale of a few hours. We simulated a flux dropout of highly relativistic 2.5 MeV electrons using the Radiation Belt Environment model, incorporating the pitch angle diffusion coefficients caused by electromagnetic ion cyclotron (EMIC) waves for the geomagnetic storm events of 23-26 October 2002. This simulation showed a remarkable decrease in the 2.5 MeV electron flux during main phase of the storm, compared to those without EMIC waves. This decrease was independent of magnetopause shadowing or drift loss to the magnetopause. We suggest that the flux decrease was likely to be primarily due to pitch angle scattering to the loss cone by EMIC waves. Furthermore, the 2.5 MeV electron flux calculated with EMIC waves correspond very well with that observed from Solar Anomalous and Magnetospheric Particle EXplorer spacecraft. EMIC wave scattering is therefore likely one of the key mechanisms to understand flux dropouts. We modeled EMIC wave intensities by the Kp index. However, the calculated dropout is a several hours earlier than the observed one. We propose that Kp is not the best parameter to predict EMIC waves.

  17. Electron beam simulation applicators

    International Nuclear Information System (INIS)

    Purdy, J.A.

    1983-01-01

    A system for simulating electron beam treatment portals using low-temperature melting point alloy is described. Special frames having the same physical dimensions as the electron beam applicators used on the Varian Clinac 20 linear accelerator were designed and constructed

  18. A Monte-Carlo simulation of the behaviour of electron swarms in hydrogen using an anisotropic scattering model

    International Nuclear Information System (INIS)

    Blevin, H.A.; Fletcher, J.; Hunter, S.R.

    1978-05-01

    In a recent paper, a Monte-Carlo simulation of electron swarms in hydrogen using an isotropic scattering model was reported. In this previous work discrepancies between the predicted and measured electron transport parameters were observed. In this paper a far more realistic anisotropic scattering model is used. Good agreement between predicted and experimental data is observed and the simulation code has been used to calculate various parameters which are not directly measurable

  19. Modelling and Simulation of National Electronic Product Code Network Demonstrator Project

    Science.gov (United States)

    Mo, John P. T.

    The National Electronic Product Code (EPC) Network Demonstrator Project (NDP) was the first large scale consumer goods track and trace investigation in the world using full EPC protocol system for applying RFID technology in supply chains. The NDP demonstrated the methods of sharing information securely using EPC Network, providing authentication to interacting parties, and enhancing the ability to track and trace movement of goods within the entire supply chain involving transactions among multiple enterprise. Due to project constraints, the actual run of the NDP was 3 months only and was unable to consolidate with quantitative results. This paper discusses the modelling and simulation of activities in the NDP in a discrete event simulation environment and provides an estimation of the potential benefits that can be derived from the NDP if it was continued for one whole year.

  20. Xyce parallel electronic simulator.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Mei, Ting; Russo, Thomas V.; Rankin, Eric Lamont; Schiek, Richard Louis; Thornquist, Heidi K.; Fixel, Deborah A.; Coffey, Todd S; Pawlowski, Roger P; Santarelli, Keith R.

    2010-05-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users Guide.

  1. Modeling and simulation of control system for electron beam machine (EBM) using programmable automation controller (PAC)

    International Nuclear Information System (INIS)

    Leo Kwee Wah; Lojius Lombigit; Abu Bakar Mhd Ghazali; Muhamad Zahidee Taat; Ayub Mohamed; Chong Foh Yoong

    2006-01-01

    An EBM electronic model is designed to simulate the control system of the Nissin EBM, which is located at Block 43, MINT complex of Jalan Dengkil with maximum output of 3 MeV, 30 mA using a Programmable Automation Controllers (PAC). This model operates likes a real EBM system where all the start-up, interlocking and stopping procedures are fully followed. It also involves formulating the mathematical models to relate certain output with the input parameters using data from actual operation on EB machine. The simulation involves a set of PAC system consisting of the digital and analogue input/output modules. The program code is written using Labview software (real-time version) on a PC and then downloaded into the PAC stand-alone memory. All the 23 interlocking signals required by the EB machine are manually controlled by mechanical switches and represented by LEDs. The EB parameters are manually controlled by potentiometers and displayed on analogue and digital meters. All these signals are then interfaced to the PC via a wifi wireless communication built-in at the PAC controller. The program is developed in accordance to the specifications and requirement of the original real EB system and displays them on the panel of the model and also on the PC monitor. All possible chances from human errors, hardware and software malfunctions, including the worst-case conditions will be tested, evaluated and modified. We hope that the performance of our model complies the requirements of operating the EB machine. It also hopes that this electronic model can replace the original PC interfacing being utilized in the Nissin EBM in the near future. The system can also be used to study the fault tolerance analysis and automatic re-configuration for advanced control of the EB system. (Author)

  2. Evaluation of computational models and cross sections used by MCNP6 for simulation of electron backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Poškus, Andrius, E-mail: andrius.poskus@ff.vu.lt

    2016-02-01

    This work evaluates the accuracy of the single-event (SE) and condensed-history (CH) models of electron transport in Monte Carlo simulations of electron backscattering from thick layers of Be, C, Al, Cu, Ag, Au and U at incident electron energies from 200 eV to 15 MeV. The CH method is used in simulations performed with MCNP6.1, and the SE method is used in simulations performed with an open-source single-event code MCNelectron written by the author of this paper. Both MCNP6.1 and MCNelectron use mainly ENDF/B-VI.8 library data, but MCNelectron allows replacing cross sections of certain types of interactions by alternative datasets from other sources. The SE method is evaluated both using only ENDF/B-VI.8 cross sections (the “SE-ENDF/B method”, which is equivalent to using MCNP6.1 in SE mode) and with an alternative set of elastic scattering cross sections obtained from relativistic (Dirac) partial-wave (DPW) calculations (the “SE-DPW method”). It is shown that at energies from 200 eV to 300 keV the estimates of the backscattering coefficients obtained using the SE-DPW method are typically within 10% of the experimental data, which is approximately the same accuracy that is achieved using MCNP6.1 in CH mode. At energies below 1 keV and above 300 keV, the SE-DPW method is much more accurate than the SE-ENDF/B method due to lack of angular distribution data in the ENDF/B library in those energy ranges. At energies from 500 keV to 15 MeV, the CH approximation is roughly twice more accurate than the SE-DPW method, with the average relative errors equal 7% and 14%, respectively. The energy probability density functions (PDFs) of backscattered electrons for Al and Cu, calculated using the SE method with DPW cross sections when energy of incident electrons is 20 keV, have an average absolute error as low as 4% of the average PDF. This error is approximately twice less than the error of the corresponding PDF calculated using the CH approximation. It is concluded

  3. Improved non-local electron thermal transport model for two-dimensional radiation hydrodynamics simulations

    International Nuclear Information System (INIS)

    Cao, Duc; Moses, Gregory; Delettrez, Jacques

    2015-01-01

    An implicit, non-local thermal conduction algorithm based on the algorithm developed by Schurtz, Nicolai, and Busquet (SNB) [Schurtz et al., Phys. Plasmas 7, 4238 (2000)] for non-local electron transport is presented and has been implemented in the radiation-hydrodynamics code DRACO. To study the model's effect on DRACO's predictive capability, simulations of shot 60 303 from OMEGA are completed using the iSNB model, and the computed shock speed vs. time is compared to experiment. Temperature outputs from the iSNB model are compared with the non-local transport model of Goncharov et al. [Phys. Plasmas 13, 012702 (2006)]. Effects on adiabat are also examined in a polar drive surrogate simulation. Results show that the iSNB model is not only capable of flux-limitation but also preheat prediction while remaining numerically robust and sacrificing little computational speed. Additionally, the results provide strong incentive to further modify key parameters within the SNB theory, namely, the newly introduced non-local mean free path. This research was supported by the Laboratory for Laser Energetics of the University of Rochester

  4. Improved non-local electron thermal transport model for two-dimensional radiation hydrodynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Duc; Moses, Gregory [University of Wisconsin—Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Delettrez, Jacques [Laboratory for Laser Energetics of the University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

    2015-08-15

    An implicit, non-local thermal conduction algorithm based on the algorithm developed by Schurtz, Nicolai, and Busquet (SNB) [Schurtz et al., Phys. Plasmas 7, 4238 (2000)] for non-local electron transport is presented and has been implemented in the radiation-hydrodynamics code DRACO. To study the model's effect on DRACO's predictive capability, simulations of shot 60 303 from OMEGA are completed using the iSNB model, and the computed shock speed vs. time is compared to experiment. Temperature outputs from the iSNB model are compared with the non-local transport model of Goncharov et al. [Phys. Plasmas 13, 012702 (2006)]. Effects on adiabat are also examined in a polar drive surrogate simulation. Results show that the iSNB model is not only capable of flux-limitation but also preheat prediction while remaining numerically robust and sacrificing little computational speed. Additionally, the results provide strong incentive to further modify key parameters within the SNB theory, namely, the newly introduced non-local mean free path. This research was supported by the Laboratory for Laser Energetics of the University of Rochester.

  5. Improved non-local electron thermal transport model for two-dimensional radiation hydrodynamics simulations

    Science.gov (United States)

    Cao, Duc; Moses, Gregory; Delettrez, Jacques

    2015-08-01

    An implicit, non-local thermal conduction algorithm based on the algorithm developed by Schurtz, Nicolai, and Busquet (SNB) [Schurtz et al., Phys. Plasmas 7, 4238 (2000)] for non-local electron transport is presented and has been implemented in the radiation-hydrodynamics code DRACO. To study the model's effect on DRACO's predictive capability, simulations of shot 60 303 from OMEGA are completed using the iSNB model, and the computed shock speed vs. time is compared to experiment. Temperature outputs from the iSNB model are compared with the non-local transport model of Goncharov et al. [Phys. Plasmas 13, 012702 (2006)]. Effects on adiabat are also examined in a polar drive surrogate simulation. Results show that the iSNB model is not only capable of flux-limitation but also preheat prediction while remaining numerically robust and sacrificing little computational speed. Additionally, the results provide strong incentive to further modify key parameters within the SNB theory, namely, the newly introduced non-local mean free path. This research was supported by the Laboratory for Laser Energetics of the University of Rochester.

  6. An improved electrical and thermal model of a microbolometer for electronic circuit simulation

    Science.gov (United States)

    Würfel, D.; Vogt, H.

    2012-09-01

    modelled more realistically when these higher order effects are taken into account. A Verilog-A model for electronic circuit simulations is developed based on the improved thermal model of the microbolometer. Finally, a simulation result of a simple circuit is presented.

  7. Geant4-DNA track-structure simulations for gold nanoparticles: The importance of electron discrete models in nanometer volumes.

    Science.gov (United States)

    Sakata, Dousatsu; Kyriakou, Ioanna; Okada, Shogo; Tran, Hoang N; Lampe, Nathanael; Guatelli, Susanna; Bordage, Marie-Claude; Ivanchenko, Vladimir; Murakami, Koichi; Sasaki, Takashi; Emfietzoglou, Dimitris; Incerti, Sebastien

    2018-05-01

    Gold nanoparticles (GNPs) are known to enhance the absorbed dose in their vicinity following photon-based irradiation. To investigate the therapeutic effectiveness of GNPs, previous Monte Carlo simulation studies have explored GNP dose enhancement using mostly condensed-history models. However, in general, such models are suitable for macroscopic volumes and for electron energies above a few hundred electron volts. We have recently developed, for the Geant4-DNA extension of the Geant4 Monte Carlo simulation toolkit, discrete physics models for electron transport in gold which include the description of the full atomic de-excitation cascade. These models allow event-by-event simulation of electron tracks in gold down to 10 eV. The present work describes how such specialized physics models impact simulation-based studies on GNP-radioenhancement in a context of x-ray radiotherapy. The new discrete physics models are compared to the Geant4 Penelope and Livermore condensed-history models, which are being widely used for simulation-based NP radioenhancement studies. An ad hoc Geant4 simulation application has been developed to calculate the absorbed dose in liquid water around a GNP and its radioenhancement, caused by secondary particles emitted from the GNP itself, when irradiated with a monoenergetic electron beam. The effect of the new physics models is also quantified in the calculation of secondary particle spectra, when originating in the GNP and when exiting from it. The new physics models show similar backscattering coefficients with the existing Geant4 Livermore and Penelope models in large volumes for 100 keV incident electrons. However, in submicron sized volumes, only the discrete models describe the high backscattering that should still be present around GNPs at these length scales. Sizeable differences (mostly above a factor of 2) are also found in the radial distribution of absorbed dose and secondary particles between the new and the existing Geant4

  8. Revisiting Vertical Models To Simulate the Line Shape of Electronic Spectra Adopting Cartesian and Internal Coordinates.

    Science.gov (United States)

    Cerezo, Javier; Santoro, Fabrizio

    2016-10-11

    Vertical models for the simulation of spectroscopic line shapes expand the potential energy surface (PES) of the final state around the equilibrium geometry of the initial state. These models provide, in principle, a better approximation of the region of the band maximum. At variance, adiabatic models expand each PES around its own minimum. In the harmonic approximation, when the minimum energy structures of the two electronic states are connected by large structural displacements, adiabatic models can breakdown and are outperformed by vertical models. However, the practical application of vertical models faces the issues related to the necessity to perform a frequency analysis at a nonstationary point. In this contribution we revisit vertical models in harmonic approximation adopting both Cartesian (x) and valence internal curvilinear coordinates (s). We show that when x coordinates are used, the vibrational analysis at nonstationary points leads to a deficient description of low-frequency modes, for which spurious imaginary frequencies may even appear. This issue is solved when s coordinates are adopted. It is however necessary to account for the second derivative of s with respect to x, which here we compute analytically. We compare the performance of the vertical model in the s-frame with respect to adiabatic models and previously proposed vertical models in x- or Q 1 -frame, where Q 1 are the normal coordinates of the initial state computed as combination of Cartesian coordinates. We show that for rigid molecules the vertical approach in the s-frame provides a description of the final state very close to the adiabatic picture. For sizable displacements it is a solid alternative to adiabatic models, and it is not affected by the issues of vertical models in x- and Q 1 -frames, which mainly arise when temperature effects are included. In principle the G matrix depends on s, and this creates nonorthogonality problems of the Duschinsky matrix connecting the normal

  9. Additive Manufacturing Modeling and Simulation A Literature Review for Electron Beam Free Form Fabrication

    Science.gov (United States)

    Seufzer, William J.

    2014-01-01

    Additive manufacturing is coming into industrial use and has several desirable attributes. Control of the deposition remains a complex challenge, and so this literature review was initiated to capture current modeling efforts in the field of additive manufacturing. This paper summarizes about 10 years of modeling and simulation related to both welding and additive manufacturing. The goals were to learn who is doing what in modeling and simulation, to summarize various approaches taken to create models, and to identify research gaps. Later sections in the report summarize implications for closed-loop-control of the process, implications for local research efforts, and implications for local modeling efforts.

  10. Digital simulation of power electronic systems

    International Nuclear Information System (INIS)

    Mehring, P.; Jentsch, W.; John, G.; Kraemer, D.

    1981-01-01

    The following paper contains the final report on the NETSIM-Project. The purpose of this project is to develop a special digital simulation system, which could serve as a base for routine application of simulation in planning and development of power electronic systems. The project is realized in two steps. First a basic network analysis system is established. With this system the basic models and methods in treating power electronic networks could be probed. The resulting system is then integrated into a general digital simulation system for continous systems (CSSL-System). This integrated simulation system allows for convenient modeling and simulation of power electronic systems. (orig.) [de

  11. Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring-High Energy Ring at the Positron-Electron Project

    International Nuclear Information System (INIS)

    Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.

    2007-01-01

    A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored

  12. Polysilicon high frequency devices for large area electronics: Characterization, simulation and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Botrel, J L [CEA-LETI 17, rue des Martyrs 38054 Grenoble (France); IMEP 23, rue des Martyrs 38016 Grenoble (France)], E-mail: jean-loius.botrel@cea.fr; Savry, O; Rozeau, O; Templier, F [CEA-LETI 17, rue des Martyrs 38054 Grenoble (France); Jomaah, J [IMEP 23, rue des Martyrs 38016 Grenoble (France)

    2007-07-16

    Laser Crystallised Polysilicon Thin Film Transistors have now sufficient good conduction properties to be used in high-frequency applications. In this work, we report the results for 5 {mu}m long polysilicon TFTs obtained at frequencies up to several hundred MHz for applications such as RFID tags or System-On-Panel. In order to investigate the device operation, DC and AC two-dimensional simulations of these devices in the Effective Medium framework have been performed. In the light of simulation results, the effects of carrier trapping and carrier transit on the device capacitances as a function of dimensions are analysed and compared. An equivalent small-signal circuit which accounts for the behaviour of these transistors in all regions of operation is proposed and a model for the most relevant elements of this circuit is presented. To validate our simulation results, scattering-parameters (S-parameters) measurements are performed for several structures such as multi-finger, serpentine and linear architectures and the most meaningful parameters will be given. Cut-off frequencies as high as 300 MHz and maximum oscillation frequencies of about 600 MHz have been extracted.

  13. Low-energy electron dose-point kernel simulations using new physics models implemented in Geant4-DNA

    Energy Technology Data Exchange (ETDEWEB)

    Bordes, Julien, E-mail: julien.bordes@inserm.fr [CRCT, UMR 1037 INSERM, Université Paul Sabatier, F-31037 Toulouse (France); UMR 1037, CRCT, Université Toulouse III-Paul Sabatier, F-31037 (France); Incerti, Sébastien, E-mail: incerti@cenbg.in2p3.fr [Université de Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Lampe, Nathanael, E-mail: nathanael.lampe@gmail.com [Université de Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Bardiès, Manuel, E-mail: manuel.bardies@inserm.fr [CRCT, UMR 1037 INSERM, Université Paul Sabatier, F-31037 Toulouse (France); UMR 1037, CRCT, Université Toulouse III-Paul Sabatier, F-31037 (France); Bordage, Marie-Claude, E-mail: marie-claude.bordage@inserm.fr [CRCT, UMR 1037 INSERM, Université Paul Sabatier, F-31037 Toulouse (France); UMR 1037, CRCT, Université Toulouse III-Paul Sabatier, F-31037 (France)

    2017-05-01

    When low-energy electrons, such as Auger electrons, interact with liquid water, they induce highly localized ionizing energy depositions over ranges comparable to cell diameters. Monte Carlo track structure (MCTS) codes are suitable tools for performing dosimetry at this level. One of the main MCTS codes, Geant4-DNA, is equipped with only two sets of cross section models for low-energy electron interactions in liquid water (“option 2” and its improved version, “option 4”). To provide Geant4-DNA users with new alternative physics models, a set of cross sections, extracted from CPA100 MCTS code, have been added to Geant4-DNA. This new version is hereafter referred to as “Geant4-DNA-CPA100”. In this study, “Geant4-DNA-CPA100” was used to calculate low-energy electron dose-point kernels (DPKs) between 1 keV and 200 keV. Such kernels represent the radial energy deposited by an isotropic point source, a parameter that is useful for dosimetry calculations in nuclear medicine. In order to assess the influence of different physics models on DPK calculations, DPKs were calculated using the existing Geant4-DNA models (“option 2” and “option 4”), newly integrated CPA100 models, and the PENELOPE Monte Carlo code used in step-by-step mode for monoenergetic electrons. Additionally, a comparison was performed of two sets of DPKs that were simulated with “Geant4-DNA-CPA100” – the first set using Geant4′s default settings, and the second using CPA100′s original code default settings. A maximum difference of 9.4% was found between the Geant4-DNA-CPA100 and PENELOPE DPKs. Between the two Geant4-DNA existing models, slight differences, between 1 keV and 10 keV were observed. It was highlighted that the DPKs simulated with the two Geant4-DNA’s existing models were always broader than those generated with “Geant4-DNA-CPA100”. The discrepancies observed between the DPKs generated using Geant4-DNA’s existing models and “Geant4-DNA-CPA100” were

  14. Simulation and modeling of whistler-mode wave growth through cyclotron resonance with energetic electrons in the magnetosphere

    International Nuclear Information System (INIS)

    Carlson, C.R.

    1987-01-01

    New models and simulations of wave growth experienced by electromagnetic waves propagating through the magnetosphere in the whistler mode are presented. For these waves, which have frequencies below the electron gyro and plasma frequencies, the magnetospheric plasma acts like a natural amplifier often amplifying the waves by ∼ 30 dB. The mechanism for growth is cyclotron resonance between the circularly polarized waves and the gyrating energetic electrons which make up the Van Allen radiation belts. The main emphasis is to simulate single-frequency wave pulses, in the 2-6 kHz range, that have been injected into the magnetosphere, near L ∼ 4, by the Stanford transmitting facility at Siple station, Antarctica. However, the results can also be applied to naturally occurring signals, signals from other transmitters, non-CW signals, and signals in other parts of the magnetosphere not probed by the Siple Station transmitter. Results show the importance of the transient aspects in the wave-growth process. The wave growth established as the wave propagates toward the equator, is given a spatially advancing wave phase structure by the geomagnetic inhomogeneity. Through the feedback of this radiation upon other electrons, conditions are set up that results in the linearly increasing output frequency with time

  15. Kinetic modeling and simulation of PCE and TCE removal in aqueous solutions by electron-beam irradiation

    International Nuclear Information System (INIS)

    Nickelsen, Michael G.; Cooper, William J.; Secker, David A.; Rosocha, Louis A.; Kurucz, Charles N.; Waite, Thomas D.

    2002-01-01

    The irradiation of aqueous solutions of TCE and PCE using a high-energy electron-beam results in the rapid decomposition of both chemicals. It is known that both TCE and PCE react with the aqueous electron and the hydroxyl radical with bimolecular rate constants greater than 10 9 M -1 s -1 for each reaction. The fact that high-energy electrons produce significant concentrations of both e aq - and ·OH radicals in water makes it an effective process for the removal of TCE and PCE from aqueous solution. We have employed steady state and computer-based chemical kinetic models to simulate and better understand the chemistry and kinetics of e-beam irradiation when applied to natural water systems. Model results were benchmarked to experimental data, allowing for the optimization of the reaction of DOC with the ·OH radical. Values for the associated second-order reaction rate constant were found to be 2.5x10 8 and 4.0x10 8 M -1 s -1 , consistent with reported values for k OH,DOC . The models were also used to investigate the possibility of incomplete irradiation during treatment and the presence of proposed chemical reactions of by-products. The reactions involve radicals and radical-adduct species formed by the reaction of TCE and PCE with the hydroxyl radical

  16. Semiconductor device models for circuit simulation power electronics; Modeles de composants semiconducteurs pour la simulation des circuits en electronique de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Berraies, M.O.

    1998-09-10

    In this thesis, an alternative strategy based on a regional approach to modeling and a new partition of the model library in the simulation is proposed. The main objective is to substitute for the usual concept of `one device, on model` that of an adaptable assembly of a limited number of submodels associated with well-identified regions of semiconductor structures. In other words, the library will only contain the primitive building-blocks of the power device models. This strategy guarantees the compatibility of the various semiconductor models in terms of physical concepts, validity domain, accuracy, homogeneity of parameter identification procedures, similarly of implementation in the simulator. This approach has been applied to PIN diodes and IGBTs for experimental validation. The next step consisted on the simulation of circuit involving several interacting devices. A simple IGBT/PIN diode chopper cell has been chosen. The results obtained compare well with experiment. This demonstrates the consistency of the proposed approach. (author) 43 refs.

  17. Optimising electron microscopy experiment through electron optics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, Y. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse France (France); Hitachi High-Technologies Corporation, 882, Ichige, Hitachinaka, Ibaraki 312-8504 (Japan); Gatel, C.; Snoeck, E. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse France (France); Houdellier, F., E-mail: florent.houdellier@cemes.fr [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse France (France)

    2017-04-15

    We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300 kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. - Highlights: • Using dedicated electron optics software, we calculate full electrons trajectories inside a modern transmission electron microscope. • We have determined how to deal with multi-scale electron optics elements like high voltage cold field emission source. • W • e have succeed to model both weak and strong magnetic lenses whether in saturated or unsaturated conditions as well as electrostatic biprism and magnetic deflectors. • We have applied this model

  18. Optimising electron microscopy experiment through electron optics simulation

    International Nuclear Information System (INIS)

    Kubo, Y.; Gatel, C.; Snoeck, E.; Houdellier, F.

    2017-01-01

    We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300 kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. - Highlights: • Using dedicated electron optics software, we calculate full electrons trajectories inside a modern transmission electron microscope. • We have determined how to deal with multi-scale electron optics elements like high voltage cold field emission source. • W • e have succeed to model both weak and strong magnetic lenses whether in saturated or unsaturated conditions as well as electrostatic biprism and magnetic deflectors. • We have applied this model

  19. Modelling and Simulating Electronics Knowledge: Conceptual Understanding and Learning through Active Agency

    Science.gov (United States)

    Twissell, Adrian

    2018-01-01

    Abstract electronics concepts are difficult to develop because the phenomena of interest cannot be readily observed. Visualisation skills support learning about electronics and can be applied at different levels of representation and understanding (observable, symbolic and abstract). Providing learners with opportunities to make transitions…

  20. Simulating radial diffusion of energetic (MeV electrons through a model of fluctuating electric and magnetic fields

    Directory of Open Access Journals (Sweden)

    T. Sarris

    2006-10-01

    Full Text Available In the present work, a test particle simulation is performed in a model of analytic Ultra Low Frequency, ULF, perturbations in the electric and magnetic fields of the Earth's magnetosphere. The goal of this work is to examine if the radial transport of energetic particles in quiet-time ULF magnetospheric perturbations of various azimuthal mode numbers can be described as a diffusive process and be approximated by theoretically derived radial diffusion coefficients. In the model realistic compressional electromagnetic field perturbations are constructed by a superposition of a large number of propagating electric and consistent magnetic pulses. The diffusion rates of the electrons under the effect of the fluctuating fields are calculated numerically through the test-particle simulation as a function of the radial coordinate L in a dipolar magnetosphere; these calculations are then compared to the symmetric, electromagnetic radial diffusion coefficients for compressional, poloidal perturbations in the Earth's magnetosphere. In the model the amplitude of the perturbation fields can be adjusted to represent realistic states of magnetospheric activity. Similarly, the azimuthal modulation of the fields can be adjusted to represent different azimuthal modes of fluctuations and the contribution to radial diffusion from each mode can be quantified. Two simulations of quiet-time magnetospheric variability are performed: in the first simulation, diffusion due to poloidal perturbations of mode number m=1 is calculated; in the second, the diffusion rates from multiple-mode (m=0 to m=8 perturbations are calculated. The numerical calculations of the diffusion coefficients derived from the particle orbits are found to agree with the corresponding theoretical estimates of the diffusion coefficient within a factor of two.

  1. Developments in electron gun simulation

    Science.gov (United States)

    Herrmannsfeldt, W. B.

    1997-01-01

    This paper will discuss the developments in the electron gun simulation programs that are based on EGUN and its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications on EGN2 of this evolution will be discussed. Some examples and a review of the capabilities of the EGUN family will be described.

  2. Developments in electron gun simulation

    International Nuclear Information System (INIS)

    Herrmannsfeldt, W.B.

    1994-05-01

    This paper will discuss the developments in the electron gun simulation programs that are based on EGUN and its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications on EGN2 of this evolution will be discussed. Some examples and a review of the capabilities of the EGUN family will be described

  3. Creating Electronic Books-Chapters for Computers and Tablets Using Easy Java/JavaScript Simulations, EjsS Modeling Tool

    OpenAIRE

    Wee, Loo Kang

    2015-01-01

    This paper shares my journey (tools used, design principles derived and modeling pedagogy implemented) when creating electronic books-chapters (epub3 format) for computers and tablets using Easy Java/JavaScript Simulations, (old name EJS, new EjsS) Modeling Tool. The theory underpinning this work grounded on learning by doing through dynamic and interactive simulation-models that can be more easily made sense of instead of the static nature of printed materials. I started combining related co...

  4. Thermal Modeling and Simulation of Electron Beam Melting for Rapid Prototyping on Ti6Al4V Alloys

    Science.gov (United States)

    Neira Arce, Alderson

    To be a viable solution for contemporary engineering challenges, the use of titanium alloys in a wider range of applications requires the development of new techniques and processes that are able to decrease production cost and delivery times. As a result, the use of material consolidation in a near-net-shape fashion, using dynamic techniques like additive manufacturing by electron beam selective melting EBSM represents a promising method for part manufacturing. However, a new product material development can be cost prohibitive, requiring the use of computer modeling and simulation as a way to decrease turnaround time. To ensure a proper representation of the EBSM process, a thermophysical material characterization and comparison was first performed on two Ti6Al4V powder feedstock materials prepared by plasma (PREP) and gas atomized (GA) processes. This evaluation comprises an evaluation on particle size distribution, density and powder surface area, collectively with the temperature dependence on properties such as heat capacity, thermal diffusivity, thermal conductivity and surface emissivity. Multiple techniques were employed in this evaluation, including high temperature differential scanning calorimetry (HT-DSC), laser flash analysis (LFA), infrared remote temperature analysis (IR-Thermography), laser diffraction, liquid and gas pycnometry using mercury and krypton adsorption respectively. This study was followed by the review of complementary strategies to simulate the temperature evolution during the EBSM process, using a finite element analysis package called COMSOL Multiphysics. Two alternatives dedicated to representing a moving heat source (electron beam) and the powder bed were developed using a step-by-step approximation initiative. The first method consisted of the depiction of a powder bed discretized on an array of domains, each one representing a static melt pool, where the moving heat source was illustrated by a series of time dependant selective

  5. Electronic Concepts Simulation Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The laboratory utilizes state-of-the-art digital models and simulations of both friendly and enemy airborne and ground-based weapon and command and control systems....

  6. Hybrid simulation of electron cyclotron resonance heating

    Energy Technology Data Exchange (ETDEWEB)

    Ropponen, T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland)], E-mail: tommi.ropponen@phys.jyu.fi; Tarvainen, O. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Suominen, P. [CERN Geneve 23, CH-1211 (Switzerland); Koponen, T.K. [Department of Physics, University of Jyvaeskylae, Nanoscience Center, P.O. Box 35, FI-40014 (Finland); Kalvas, T.; Koivisto, H. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland)

    2008-03-11

    Electron Cyclotron Resonance (ECR) heating is a fundamentally important aspect in understanding the physics of Electron Cyclotron Resonance Ion Sources (ECRIS). Absorption of the radio frequency (RF) microwave power by electron heating in the resonance zone depends on many parameters including frequency and electric field strength of the microwave, magnetic field structure and electron and ion density profiles. ECR absorption has been studied in the past by e.g. modelling electric field behaviour in the resonance zone and its near proximity. This paper introduces a new ECR heating code that implements damping of the microwave power in the vicinity of the resonance zone, utilizes electron density profiles and uses right hand circularly polarized (RHCP) electromagnetic waves to simulate electron heating in ECRIS plasma.

  7. Contribution to the modelling and multi-scale numerical simulation of kinetic electron transport in hot plasma

    International Nuclear Information System (INIS)

    Mallet, J.

    2012-01-01

    This research thesis stands at the crossroad of plasma physics, numerical analysis and applied mathematics. After an introduction presenting the problematic and previous works, the author recalls some basis of classical kinetic models for plasma physics (collisionless kinetic theory and Vlasov equation, collisional kinetic theory with the non-relativistic Maxwell-Fokker-Plansk system) and describes the fundamental properties of the collision operators such as conservation laws, entropy dissipation, and so on. He reports the improvement of a deterministic numerical method to solve the non-relativistic Vlasov-Maxwell system coupled with Fokker-Planck-Landau type operators. The efficiency of each high order scheme is compared. The evolution of the hot spot is studied in the case of thermonuclear reactions in the centre of the pellet in a weakly collisional regime. The author focuses on the simulation of the kinetic electron collisional transport in inertial confinement fusion (ICF) between the laser absorption zone and the ablation front. A new approach is then introduced to reduce the huge computation time obtained with kinetic models. In a last chapter, the kinetic continuous equation in spherical domain is described and a new model is chosen for collisions in order to preserve collision properties

  8. Tabulated square-shaped source model for linear accelerator electron beam simulation

    Directory of Open Access Journals (Sweden)

    Navid Khaledi

    2017-01-01

    Conclusions: Our study demonstrates that there was an excellent agreement between the results of our proposed model and measured data; furthermore, an optimum calculation speed was achieved because there was no need to define geometry and materials in the LINAC head.

  9. Modeling of a Micro-Electronic Mechanical Systems (MEMS) Deformable Mirror for Simulation and Characterization

    Science.gov (United States)

    2016-09-01

    quarter wave plates and the polarized beam splitter without being affected. These plates and beam splitter were part of the layout because the system in...1  II.  MODEL DESIGN ...of different methods for deposition, patterning, and etching until the desired design of the device is achieved. While a large number of devices

  10. Simulations of free electron laser

    International Nuclear Information System (INIS)

    Kwan, T.; Godfrey, B.B.

    1979-01-01

    The generation of coherent electromagnetic radiation by the interaction of a relativistic electron beam with a static helical magnetic field is investigated using one- and two-dimensional relativistic electromagnetic plasma simulation codes. In the one-dimensional simulations, we observed the coupling between the negative energy beam mode and the positive energy electromagnetic wave. Substantial growth rate (omega 1 approx. 0.1 omega/sub pe/) of the unstable electromagnetic wave has been observed and efficiency of radiation production is found to be between 25 to 30% depending on various parameters. In the two-dimensional simulations, we observed a decrease in the growth rate, but increased efficiency due to the decrease in the phase velocity of the unstable electrostatic wave. In addition, we also observed waves propagating at an angle with respect to the electron beam. Consequently, the beam is bunched in the radial as well as the axial directions. These waves are believed to be generated by another instability which saturates at relatively low level

  11. Teaching Students to Model Neural Circuits and Neural Networks Using an Electronic Spreadsheet Simulator. Microcomputing Working Paper Series.

    Science.gov (United States)

    Hewett, Thomas T.

    There are a number of areas in psychology where an electronic spreadsheet simulator can be used to study and explore functional relationships among a number of parameters. For example, when dealing with sensation, perception, and pattern recognition, it is sometimes desirable for students to understand both the basic neurophysiology and the…

  12. Xyce parallel electronic simulator design.

    Energy Technology Data Exchange (ETDEWEB)

    Thornquist, Heidi K.; Rankin, Eric Lamont; Mei, Ting; Schiek, Richard Louis; Keiter, Eric Richard; Russo, Thomas V.

    2010-09-01

    This document is the Xyce Circuit Simulator developer guide. Xyce has been designed from the 'ground up' to be a SPICE-compatible, distributed memory parallel circuit simulator. While it is in many respects a research code, Xyce is intended to be a production simulator. As such, having software quality engineering (SQE) procedures in place to insure a high level of code quality and robustness are essential. Version control, issue tracking customer support, C++ style guildlines and the Xyce release process are all described. The Xyce Parallel Electronic Simulator has been under development at Sandia since 1999. Historically, Xyce has mostly been funded by ASC, the original focus of Xyce development has primarily been related to circuits for nuclear weapons. However, this has not been the only focus and it is expected that the project will diversify. Like many ASC projects, Xyce is a group development effort, which involves a number of researchers, engineers, scientists, mathmaticians and computer scientists. In addition to diversity of background, it is to be expected on long term projects for there to be a certain amount of staff turnover, as people move on to different projects. As a result, it is very important that the project maintain high software quality standards. The point of this document is to formally document a number of the software quality practices followed by the Xyce team in one place. Also, it is hoped that this document will be a good source of information for new developers.

  13. Electron cloud simulation of the ECR plasma

    International Nuclear Information System (INIS)

    Racz, R.; Biri, S.; Palinkas, J.

    2011-01-01

    Complete text of publication follows. The plasma of the Electron Cyclotron Resonance Ion Source (ECRIS) of ATOMKI is being continuously investigated by different diagnostic methods: using small-sized probes or taking X-ray and visible light photographs. In 2011 three articles were published by our team in a special edition of the IEEE Transactions on Plasma Science (Special Issue on Images in Plasma Science) describing our X-ray and visible light measurements and plasma modeling and simulating studies. Simulation is in many cases the base for the analysis of the photographs. The outcomes of the X-ray and visible light experiments were presented already in earlier issues of the Atomki Annual Report, therefore in this year we concentrate on the results of the simulating studies. The spatial distribution of the three main electron components (cold, warm and hot electron clouds) of the ECR plasmas was simulated by TrapCAD code. TrapCAD is a 'limited' plasma simulation code. The spatial and energy evolution of a large number of electrons can be realistically followed; however, these particles are independent, and no particle interactions are included. In ECRISs, the magnetic trap confines the electrons which keep together the ion component by their space charge. The electrons gain high energies while the ions remain very cold throughout the whole process. Thus, the spatial and energy simulation of the electron component gives much important and numerical information even for the ions. The electron components of ECRISs can artificially be grouped into three populations: cold, warm, and hot electrons. Cold electrons (1-200 eV) have not been heated by the microwave; they are mainly responsible for the visible light emission of the plasma. The energized warm electrons (several kiloelectronvolts) are able to ionize atoms and ions and they are mainly responsible for the characteristic Xray photons emitted by the plasma. Electrons having much higher energy than necessary for

  14. A multi-band, multi-level, multi-electron model for efficient FDTD simulations of electromagnetic interactions with semiconductor quantum wells

    Science.gov (United States)

    Ravi, Koustuban; Wang, Qian; Ho, Seng-Tiong

    2015-08-01

    We report a new computational model for simulations of electromagnetic interactions with semiconductor quantum well(s) (SQW) in complex electromagnetic geometries using the finite-difference time-domain method. The presented model is based on an approach of spanning a large number of electron transverse momentum states in each SQW sub-band (multi-band) with a small number of discrete multi-electron states (multi-level, multi-electron). This enables accurate and efficient two-dimensional (2-D) and three-dimensional (3-D) simulations of nanophotonic devices with SQW active media. The model includes the following features: (1) Optically induced interband transitions between various SQW conduction and heavy-hole or light-hole sub-bands are considered. (2) Novel intra sub-band and inter sub-band transition terms are derived to thermalize the electron and hole occupational distributions to the correct Fermi-Dirac distributions. (3) The terms in (2) result in an explicit update scheme which circumvents numerically cumbersome iterative procedures. This significantly augments computational efficiency. (4) Explicit update terms to account for carrier leakage to unconfined states are derived, which thermalize the bulk and SQW populations to a common quasi-equilibrium Fermi-Dirac distribution. (5) Auger recombination and intervalence band absorption are included. The model is validated by comparisons to analytic band-filling calculations, simulations of SQW optical gain spectra, and photonic crystal lasers.

  15. A model and computer code for the Monte Carlo simulation of relativistic electron and positron penetration through matter

    International Nuclear Information System (INIS)

    Ismail, M.; Liljequist, D.

    1986-10-01

    In the present model, the treatment of elastic scattering is based on the similarity of multiple scattering processes with equal transport mean free path /LAMBDA/sub(tr). Elastic scattering events are separated by an artificially enlarged mean free path. In such events, scattering is optionally performed either by means of a single, energy-dependent scattering angle, or by means of a scattering angle distribution of the same form as the screened Rutherford cross section, but with an artificial screening factor. The physically correct /LAMBDA/sub(tr) value is obtained by appropriate choice of scattering angle or screening factor, respectively. We find good agreement with experimental transmission and with energy loss distributions. The Rutherford-like model gives good agreement with experimental angular distribution even for the penetration of very thin layers. Treatment of electron energy loss is based on the partial CSDA method: energy losses W WMINSE are treated as discrete electron-electron or positron-electron scattering events. Similarly, for bremsstrahlung photon energies W WMINR are treated at discrete events. The sensitivity of the model to the parameters WMINSE and WMINR is studied. WMINR can, in practise, be made negligibly small, and WMINSE can without any excessive computer time be made as small as to give results in good agreement with experiment and with computations based on Landau theory of straggling. Using this model, we study some of the characteristic features of relativistic electron transmission, energy loss distributions, straggling, angular distributions and trajectories. (authors)

  16. Simulating Policy Processes through Electronic Mail.

    Science.gov (United States)

    Flynn, John P.

    1987-01-01

    Focuses on the use of electronic mail for teaching and learning about social welfare policy processes and compares electronic mail as a simulation medium to more structured computer applications. (Author)

  17. Xyce parallel electronic simulator : reference guide.

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Warrender, Christina E.; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2011-05-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users Guide. The Xyce Parallel Electronic Simulator has been written to support, in a rigorous manner, the simulation needs of the Sandia National Laboratories electrical designers. It is targeted specifically to run on large-scale parallel computing platforms but also runs well on a variety of architectures including single processor workstations. It also aims to support a variety of devices and models specific to Sandia needs. This document is intended to complement the Xyce Users Guide. It contains comprehensive, detailed information about a number of topics pertinent to the usage of Xyce. Included in this document is a netlist reference for the input-file commands and elements supported within Xyce; a command line reference, which describes the available command line arguments for Xyce; and quick-references for users of other circuit codes, such as Orcad's PSpice and Sandia's ChileSPICE.

  18. Electron gun simulation with CST PARTICLE STUDIO

    International Nuclear Information System (INIS)

    Spachmann, Holger; Becker, Ulrich

    2006-01-01

    This paper introduces CST PARTICLE STUDIO TM , a specialist tool for the fast and accurate design and analysis of 3D electron guns. The new software is based on the multi-purpose electromagnetic solvers of the CST STUDIO family and incorporates their powerful modelling capabilities as well as successful algorithms of the MAFIA-TS simulators. The underlying theory of the PBA based field solvers and the used tracking technique is presented and some examples of application demonstrate the current status of the software

  19. Simulations of the ILC Electron Gun and Electron Bunching System

    International Nuclear Information System (INIS)

    Haakonsen, C.B.; McGill U.

    2006-01-01

    The International Linear Collider (ILC) is a proposed electron-positron collider, expected to provide insight into important questions in particle physics. A part of the global R and D effort for the ILC is the design of its electron gun and electron bunching system. The present design of the bunching system has two sub-harmonic bunchers, one operating at 108 MHz and one at 433MHz, and two 5-cell 1.3 GHz (L-band) bunchers. This bunching system has previously been simulated using the Phase and Radial Motion in Electron Linear Accelerators (PARMELA) software, and those simulations indicated that the design provides sufficient bunching and acceleration. Due to the complicated dynamics governing the electrons in the bunching system we decided to verify and expand the PARMELA results using the more recent and independent simulation software General Particle Tracer (GPT). GPT tracks the motion and interactions of a set of macro particles, each of which represent a number of electrons, and provides a variety of analysis capabilities. To provide initial conditions for the macro particles, a method was developed for deriving the initial conditions from detailed simulations of particle trajectories in the electron gun. These simulations were performed using the Egun software. For realistic simulation of the L-band bunching cavities, their electric and magnetic fields were calculated using the Superfish software and imported into GPT. The GPT simulations arrived at similar results to the PARMELA simulations for sub-harmonic bunching. However, using GPT it was impossible to achieve an efficient bunching performance of the first L-band bunching cavity. To correct this, the first L-band buncher cell was decoupled from the remaining 4 cells and driven as an independent cavity. Using this modification we attained results similar to the PARMELA simulations. Although the modified bunching system design performed as required, the modifications are technically challenging to implement

  20. Simulation modeling and arena

    CERN Document Server

    Rossetti, Manuel D

    2015-01-01

    Emphasizes a hands-on approach to learning statistical analysis and model building through the use of comprehensive examples, problems sets, and software applications With a unique blend of theory and applications, Simulation Modeling and Arena®, Second Edition integrates coverage of statistical analysis and model building to emphasize the importance of both topics in simulation. Featuring introductory coverage on how simulation works and why it matters, the Second Edition expands coverage on static simulation and the applications of spreadsheets to perform simulation. The new edition als

  1. Modeling Incoherent Electron Cloud Effects

    International Nuclear Information System (INIS)

    Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D.; Sonnad, K.; Tomas, R.; Vay, J.-L.; Zimmermann, F.; Rumolo, G.; Pivi, M.; Raubenheimer, T.

    2007-01-01

    Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed

  2. Aviation Safety Simulation Model

    Science.gov (United States)

    Houser, Scott; Yackovetsky, Robert (Technical Monitor)

    2001-01-01

    The Aviation Safety Simulation Model is a software tool that enables users to configure a terrain, a flight path, and an aircraft and simulate the aircraft's flight along the path. The simulation monitors the aircraft's proximity to terrain obstructions, and reports when the aircraft violates accepted minimum distances from an obstruction. This model design facilitates future enhancements to address other flight safety issues, particularly air and runway traffic scenarios. This report shows the user how to build a simulation scenario and run it. It also explains the model's output.

  3. Electron-cloud simulation results for the PSR and SNS

    International Nuclear Information System (INIS)

    Pivi, M.; Furman, M.A.

    2002-01-01

    We present recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos. In particular, a complete refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has been included in the simulation code

  4. Electronic analogue simulator of radio cardiograms

    International Nuclear Information System (INIS)

    Roux, G.; Lansiart, A.; Vernejoul, P. de; Kellershohn, C.

    1967-01-01

    The various parameters of the heart pump and of the blood circulation can be determined by radio-cardio-graphical techniques. The curves thus obtained can be more easily used in radiocardiography if the electronic analogue simulator described here is employed. The experimental and simulated radio-cardiograms are made to coincide by varying the electrical parameters of the simulator. Using simple charts it is possible to obtain directly the actual original physiological parameters from these electrical parameters. Some examples are given showing the excellent accuracy obtained in the determination of ejection indices by the simulator. (authors) [fr

  5. Simulation in Complex Modelling

    DEFF Research Database (Denmark)

    Nicholas, Paul; Ramsgaard Thomsen, Mette; Tamke, Martin

    2017-01-01

    This paper will discuss the role of simulation in extended architectural design modelling. As a framing paper, the aim is to present and discuss the role of integrated design simulation and feedback between design and simulation in a series of projects under the Complex Modelling framework. Complex...... performance, engage with high degrees of interdependency and allow the emergence of design agency and feedback between the multiple scales of architectural construction. This paper presents examples for integrated design simulation from a series of projects including Lace Wall, A Bridge Too Far and Inflated...... Restraint developed for the research exhibition Complex Modelling, Meldahls Smedie Gallery, Copenhagen in 2016. Where the direct project aims and outcomes have been reported elsewhere, the aim for this paper is to discuss overarching strategies for working with design integrated simulation....

  6. Scientific Modeling and simulations

    CERN Document Server

    Diaz de la Rubia, Tomás

    2009-01-01

    Showcases the conceptual advantages of modeling which, coupled with the unprecedented computing power through simulations, allow scientists to tackle the formibable problems of our society, such as the search for hydrocarbons, understanding the structure of a virus, or the intersection between simulations and real data in extreme environments

  7. Computer Modeling and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Pronskikh, V. S. [Fermilab

    2014-05-09

    Verification and validation of computer codes and models used in simulation are two aspects of the scientific practice of high importance and have recently been discussed by philosophers of science. While verification is predominantly associated with the correctness of the way a model is represented by a computer code or algorithm, validation more often refers to model’s relation to the real world and its intended use. It has been argued that because complex simulations are generally not transparent to a practitioner, the Duhem problem can arise for verification and validation due to their entanglement; such an entanglement makes it impossible to distinguish whether a coding error or model’s general inadequacy to its target should be blamed in the case of the model failure. I argue that in order to disentangle verification and validation, a clear distinction between computer modeling (construction of mathematical computer models of elementary processes) and simulation (construction of models of composite objects and processes by means of numerical experimenting with them) needs to be made. Holding on to that distinction, I propose to relate verification (based on theoretical strategies such as inferences) to modeling and validation, which shares the common epistemology with experimentation, to simulation. To explain reasons of their intermittent entanglement I propose a weberian ideal-typical model of modeling and simulation as roles in practice. I suggest an approach to alleviate the Duhem problem for verification and validation generally applicable in practice and based on differences in epistemic strategies and scopes

  8. Automated Simulation Model Generation

    NARCIS (Netherlands)

    Huang, Y.

    2013-01-01

    One of today's challenges in the field of modeling and simulation is to model increasingly larger and more complex systems. Complex models take long to develop and incur high costs. With the advances in data collection technologies and more popular use of computer-aided systems, more data has become

  9. Modeling microwave/electron-cloud interaction

    International Nuclear Information System (INIS)

    Mattes, M; Sorolla, E; Zimmermann, F

    2013-01-01

    Starting from the separate codes BI-RME and ECLOUD or PyECLOUD, we are developing a novel joint simulation tool, which models the combined effect of a charged particle beam and of microwaves on an electron cloud. Possible applications include the degradation of microwave transmission in telecommunication satellites by electron clouds; the microwave-transmission techniques being used in particle accelerators for the purpose of electroncloud diagnostics; the microwave emission by the electron cloud itself in the presence of a magnetic field; and the possible suppression of electron-cloud formation in an accelerator by injecting microwaves of suitable amplitude and frequency. A few early simulation results are presented. (author)

  10. Evaluation of computational models and cross sections used by MCNP6 for simulation of characteristic X-ray emission from thick targets bombarded by kiloelectronvolt electrons

    Energy Technology Data Exchange (ETDEWEB)

    Poškus, A., E-mail: andrius.poskus@ff.vu.lt

    2016-09-15

    This paper evaluates the accuracy of the single-event (SE) and condensed-history (CH) models of electron transport in MCNP6.1 when simulating characteristic K{sub α}, total K (=K{sub α} + K{sub β}) and L{sub α} X-ray emission from thick targets bombarded by electrons with energies from 5 keV to 30 keV. It is shown that the MCNP6.1 implementation of the CH model for the K-shell impact ionization leads to underestimation of the K yield by 40% or more for the elements with atomic numbers Z < 15 and overestimation of the K{sub α} yield by more than 40% for the elements with Z > 25. The L{sub α} yields are underestimated by more than an order of magnitude in CH mode, because MCNP6.1 neglects X-ray emission caused by electron-impact ionization of L, M and higher shells in CH mode (the L{sub α} yields calculated in CH mode reflect only X-ray fluorescence, which is mainly caused by photoelectric absorption of bremsstrahlung photons). The X-ray yields calculated by MCNP6.1 in SE mode (using ENDF/B-VII.1 library data) are more accurate: the differences of the calculated and experimental K yields are within the experimental uncertainties for the elements C, Al and Si, and the calculated K{sub α} yields are typically underestimated by (20–30)% for the elements with Z > 25, whereas the L{sub α} yields are underestimated by (60–70)% for the elements with Z > 49. It is also shown that agreement of the experimental X-ray yields with those calculated in SE mode is additionally improved by replacing the ENDF/B inner-shell electron-impact ionization cross sections with the set of cross sections obtained from the distorted-wave Born approximation (DWBA), which are also used in the PENELOPE code system. The latter replacement causes a decrease of the average relative difference of the experimental X-ray yields and the simulation results obtained in SE mode to approximately 10%, which is similar to accuracy achieved with PENELOPE. This confirms that the DWBA inner

  11. AEGIS geologic simulation model

    International Nuclear Information System (INIS)

    Foley, M.G.

    1982-01-01

    The Geologic Simulation Model (GSM) is used by the AEGIS (Assessment of Effectiveness of Geologic Isolation Systems) program at the Pacific Northwest Laboratory to simulate the dynamic geology and hydrology of a geologic nuclear waste repository site over a million-year period following repository closure. The GSM helps to organize geologic/hydrologic data; to focus attention on active natural processes by requiring their simulation; and, through interactive simulation and calibration, to reduce subjective evaluations of the geologic system. During each computer run, the GSM produces a million-year geologic history that is possible for the region and the repository site. In addition, the GSM records in permanent history files everything that occurred during that time span. Statistical analyses of data in the history files of several hundred simulations are used to classify typical evolutionary paths, to establish the probabilities associated with deviations from the typical paths, and to determine which types of perturbations of the geologic/hydrologic system, if any, are most likely to occur. These simulations will be evaluated by geologists familiar with the repository region to determine validity of the results. Perturbed systems that are determined to be the most realistic, within whatever probability limits are established, will be used for the analyses that involve radionuclide transport and dose models. The GSM is designed to be continuously refined and updated. Simulation models are site specific, and, although the submodels may have limited general applicability, the input data equirements necessitate detailed characterization of each site before application

  12. Model improvements to simulate charging in SEM

    Science.gov (United States)

    Arat, K. T.; Klimpel, T.; Hagen, C. W.

    2018-03-01

    Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. The improvements include both modelling of low energy electron scattering and charging of insulators. The new first-principle scattering models provide a more realistic charge distribution cloud in the material, and a better match between non-charging simulations and experimental results. Improvements on charging models mainly focus on redistribution of the charge carriers in the material with an induced conductivity (EBIC) and a breakdown model, leading to a smoother distribution of the charges. Combined with a more accurate tracing of low energy electrons in the electric field, we managed to reproduce the dynamically changing charging contrast due to an induced positive surface potential.

  13. Validation of simulation models

    DEFF Research Database (Denmark)

    Rehman, Muniza; Pedersen, Stig Andur

    2012-01-01

    In philosophy of science, the interest for computational models and simulations has increased heavily during the past decades. Different positions regarding the validity of models have emerged but the views have not succeeded in capturing the diversity of validation methods. The wide variety...

  14. Correcting Misconceptions on Electronics: Effects of a Simulation-Based Learning Environment Backed by a Conceptual Change Model

    Science.gov (United States)

    Chen, Yu-Lung; Pan, Pei-Rong; Sung, Yao-Ting; Chang, Kuo-En

    2013-01-01

    Computer simulation has significant potential as a supplementary tool for effective conceptual-change learning based on the integration of technology and appropriate instructional strategies. This study elucidates misconceptions in learning on diodes and constructs a conceptual-change learning system that incorporates…

  15. Simulation of Coulomb interaction effects in electron sources

    International Nuclear Information System (INIS)

    Rouse, John; Zhu Xieqing; Liu Haoning; Munro, Eric

    2011-01-01

    Over many years, we have developed electron source simulation software that has been used widely in the electron optics community to aid the development of rotationally symmetric electron and ion guns. The simulation includes the modelling of cathode emission and the effects of volumetric space charge. In the present paper we describe the existing software and explain how we have extended this software to include the effects of discrete Coulomb interactions between the electrons as they travel from the cathode surface to the exit of the gun. In the paper, we will describe the numerical models we have employed, the techniques we have used to maximize the speed of the Coulomb force computation and present several illustrative examples of cases analyzed using the new software, including thermal field emitters, LaB 6 guns and flat dispenser-type cathodes.

  16. Simulation of electron thermal transport in H-mode discharges

    International Nuclear Information System (INIS)

    Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.

    2009-01-01

    Electron thermal transport in DIII-D H-mode tokamak plasmas [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis (ASTRA) integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient (ETG) anomalous transport and trapped electron mode (TEM) anomalous transport, as well as a model for paleoclassical transport [J. D. Callen, Nucl. Fusion 45, 1120 (2005)]. It is found that the electromagnetic limit of the Horton ETG model [W. Horton et al., Phys. Fluids 31, 2971 (1988)] provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model [R. E. Waltz et al., Phys. Plasmas 4, 2482 (1997)] is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to -4%.

  17. Numerical simulation of RCS for carrier electronic warfare airplanes

    Directory of Open Access Journals (Sweden)

    Yue Kuizhi

    2015-04-01

    Full Text Available This paper studies the radar cross section (RCS of carrier electronic warfare airplanes. Under the typical naval operations section, the mathematical model of the radar wave’s pitch angle incidence range analysis is established. Based on the CATIA software, considering dynamic deflections of duck wing leading edge flaps, flaperons, horizontal tail, and rudder, as well as aircraft with air-to-air missile, anti-radiation missile, electronic jamming pod, and other weapons, the 3D models of carrier electronic warfare airplanes Model A and Model B with weapons were established. Based on the physical optics method and the equivalent electromagnetic flow method, by the use of the RCSAnsys software, the characteristics of carrier electronic warfare airplanes’ RCS under steady and dynamic flights were simulated under the UHF, X, and S radar bands. This paper researches the detection probability of aircraft by radars under the condition of electronic warfare, and completes the mathematical statistical analysis of the simulation results. The results show that: The Model A of carrier electronic warfare airplane is better than Model B on stealth performance and on discover probability by radar detection effectively.

  18. Modelling transport in single electron transistor

    International Nuclear Information System (INIS)

    Dinh Sy Hien; Huynh Lam Thu Thao; Le Hoang Minh

    2009-01-01

    We introduce a model of single electron transistor (SET). Simulation programme of SET is used as the exploratory tool in order to gain better understanding of process and device physics. This simulator includes a graphic user interface (GUI) in Matlab. The SET was simulated using GUI in Matlab to get current-voltage (I-V) characteristics. In addition, effects of device capacitance, bias, temperature on the I-V characteristics were obtained. In this work, we review the capabilities of the simulator of the SET. Typical simulations of the obtained I-V characteristics of the SET are presented.

  19. Simulation of tokamak runaway-electron events

    International Nuclear Information System (INIS)

    Bolt, H.; Miyahara, A.; Miyake, M.; Yamamoto, T.

    1987-08-01

    High energy runaway-electron events which can occur in tokamaks when the plasma hits the first wall are a critical issue for the materials selection of future devices. Runaway-electron events are simulated with an electron linear accelerator to better understand the observed runaway-electron damage to tokamak first wall materials and to consider the runaway-electron issue in further materials development and selection. The electron linear accelerator produces beam energies of 20 to 30 MeV at an integrated power input of up to 1.3 kW. Graphite, SiC + 2 % AlN, stainless steel, molybdenum and tungsten have been tested as bulk materials. To test the reliability of actively cooled systems under runaway-electron impact layer systems of graphite fixed to metal substrates have been tested. The irradiation resulted in damage to the metal compounds but left graphite and SiC + 2 % AlN without damage. Metal substrates of graphite - metal systems for actively cooled structures suffer severe damage unless thick graphite shielding is provided. (author)

  20. Potential formation in a one-dimensional bounded plasma system containing a two-electron temperature plasma: Kinetic model and PIC simulation

    International Nuclear Information System (INIS)

    Gyergyek, T.; Jurcic-Zlobec, B.; Cercek, M.

    2008-01-01

    Potential formation in a bounded plasma system that contains electrons with a two-temperature velocity distribution and is terminated by a floating, electron emitting electrode (collector) is studied by a one-dimensional kinetic model. A method on how to determine the boundary conditions at the collector for the numerical solution of the Poisson equation is presented. The difference between the regular and the irregular numerical solutions of the Poisson equation is explained. The regular numerical solution of the Poisson equation fulfills the boundary conditions at the source and can be computed for any distance from the collector. The irregular solution does not fulfill the source boundary conditions and the computation breaks down at some distance from the collector. An excellent agreement of the values of the potential at the inflection point found from the numerical solution of the Poisson equation with the values predicted by the analytical model is obtained. Potential, electric field, and particle density profiles found by the numerical solution of the Poisson equation are compared to the profiles obtained with the particle in cell computer simulation. A very good quantitative agreement of the potential and electric field profiles is obtained. For certain values of the parameters the analytical model predicts three possible values of the potential at the inflection point. In such cases always only one of the corresponding numerical solutions of the Poisson equation is regular, while the other two are irregular. The regular numerical solution of the Poisson equation always corresponds to the solution of the model that predicts the largest ion flux to the collector

  1. Xyce parallel electronic simulator release notes.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Hoekstra, Robert John; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Thornquist, Heidi K.; Rankin, Eric Lamont; Coffey, Todd S; Pawlowski, Roger P; Santarelli, Keith R.

    2010-05-01

    The Xyce Parallel Electronic Simulator has been written to support, in a rigorous manner, the simulation needs of the Sandia National Laboratories electrical designers. Specific requirements include, among others, the ability to solve extremely large circuit problems by supporting large-scale parallel computing platforms, improved numerical performance and object-oriented code design and implementation. The Xyce release notes describe: Hardware and software requirements New features and enhancements Any defects fixed since the last release Current known defects and defect workarounds For up-to-date information not available at the time these notes were produced, please visit the Xyce web page at http://www.cs.sandia.gov/xyce.

  2. Models and simulations

    International Nuclear Information System (INIS)

    Lee, M.J.; Sheppard, J.C.; Sullenberger, M.; Woodley, M.D.

    1983-09-01

    On-line mathematical models have been used successfully for computer controlled operation of SPEAR and PEP. The same model control concept is being implemented for the operation of the LINAC and for the Damping Ring, which will be part of the Stanford Linear Collider (SLC). The purpose of this paper is to describe the general relationships between models, simulations and the control system for any machine at SLAC. The work we have done on the development of the empirical model for the Damping Ring will be presented as an example

  3. PSH Transient Simulation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-12-21

    PSH Transient Simulation Modeling presentation from the WPTO FY14 - FY16 Peer Review. Transient effects are an important consideration when designing a PSH system, yet numerical techniques for hydraulic transient analysis still need improvements for adjustable-speed (AS) reversible pump-turbine applications.

  4. Wake modeling and simulation

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Madsen Aagaard, Helge; Larsen, Torben J.

    We present a consistent, physically based theory for the wake meandering phenomenon, which we consider of crucial importance for the overall description of wind turbine loadings in wind farms. In its present version the model is confined to single wake situations. The model philosophy does, howev...... methodology has been implemented in the aeroelastic code HAWC2, and example simulations of wake situations, from the small Tjæreborg wind farm, have been performed showing satisfactory agreement between predictions and measurements...

  5. A computer simulation of auger electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ragheb, M S; Bakr, M H.S. [Dept. Of Accellerators and Ion Sources, Division of Basic Nuclear Sciences, NRC, Atomic Energy Authority, (Egypt)

    1997-12-31

    A simulation study of Auger electron spectroscopy was performed to reveal how far the dependency between the different parameters governing the experimental behavior affects the peaks. The experimental procedure followed by the AC modulation technique were reproduced by means of a computer program. It generates the assumed output Auger electron peaks, exposes them to a retarding AC modulated field and collects the resulting modulated signals. The program produces the lock-in treatment in order to demodulate the signals revealing the Auger peaks. It analyzes the spectrum obtained giving the peak positions and energies. Comparison between results of simulation and the experimental data showed good agreement. The peaks of the spectrum obtained depend upon the amplitude, frequency and resolution of the applied modulated signal. The peak shape is effected by the rise time, the slope and the starting potential of the retarding field. 4 figs.

  6. A spectral unaveraged algorithm for free electron laser simulations

    International Nuclear Information System (INIS)

    Andriyash, I.A.; Lehe, R.; Malka, V.

    2015-01-01

    We propose and discuss a numerical method to model electromagnetic emission from the oscillating relativistic charged particles and its coherent amplification. The developed technique is well suited for free electron laser simulations, but it may also be useful for a wider range of physical problems involving resonant field–particles interactions. The algorithm integrates the unaveraged coupled equations for the particles and the electromagnetic fields in a discrete spectral domain. Using this algorithm, it is possible to perform full three-dimensional or axisymmetric simulations of short-wavelength amplification. In this paper we describe the method, its implementation, and we present examples of free electron laser simulations comparing the results with the ones provided by commonly known free electron laser codes

  7. Analysis and simulation of BGK electron holes

    Directory of Open Access Journals (Sweden)

    L. Muschietti

    1999-01-01

    Full Text Available Recent observations from satellites crossing regions of magnetic-field-aligned electron streams reveal solitary potential structures that move at speeds much greater than the ion acoustic/thermal velocity. The structures appear as positive potential pulses rapidly drifting along the magnetic field, and are electrostatic in their rest frame. We interpret them as BGK electron holes supported by a drifting population of trapped electrons. Using Laplace transforms, we analyse the behavior of one phase-space electron hole. The resulting potential shapes and electron distribution functions are self-consistent and compatible with the field and particle data associated with the observed pulses. In particular, the spatial width increases with increasing amplitude. The stability of the analytic solution is tested by means of a two-dimensional particle-in-cell simulation code with open boundaries. We consider a strongly magnetized parameter regime in which the bounce frequency of the trapped electrons is much less than their gyrofrequency. Our investigation includes the influence of the ions, which in the frame of the hole appear as an incident beam, and impinge on the BGK potential with considerable energy. The nonlinear structure is remarkably resilient

  8. Simulation of electron cloud effects to heavy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, Fatih; Gjonaj, Erion; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder

    2011-07-01

    Electron cloud (EC) driven instability can cause beam loss, emittance growth, trajectory change and wake fields. Mentioned crucial effects of EC motivated researchers to understand the EC build up mechanism and the effects of EC to the beam. This motivation also induced the progress of developing new simulation codes. EC simulations can roughly be divided into two classes such as, softwares whose goals are to simulate the build up of the EC during the passage of a bunch train and the codes which model the interaction of a bunch with an EC. The aim of this study is to simulate the effects of electron cloud (EC) on the dynamics of heavy ion beams which are used in heavy ion synchrotron (SIS-18) at GSI. To do this, a 3-D and self-consistent simulation program based on particle in cell (PIC) method is used. In the PIC cycle, accurate solution of the Maxwell equations is obtained by employing discontinuous Galerkin finite element method. As a model, we assumed a perfectly conducting beam pipe which was uniformly (or randomly) loaded with the electrons. Then as parallel with the realistic cases in SIS-18, a single bunch consisting of U{sup +73} ions was extracted which could propagate in this pipe. Due to EC-ion bunch interaction, electrons gained energy and their displacements were observed. Electric and magnetic field components and EC charge density were calculated, numerically.

  9. Effect of battery longevity on costs and health outcomes associated with cardiac implantable electronic devices: a Markov model-based Monte Carlo simulation.

    Science.gov (United States)

    Schmier, Jordana K; Lau, Edmund C; Patel, Jasmine D; Klenk, Juergen A; Greenspon, Arnold J

    2017-11-01

    The effects of device and patient characteristics on health and economic outcomes in patients with cardiac implantable electronic devices (CIEDs) are unclear. Modeling can estimate costs and outcomes for patients with CIEDs under a variety of scenarios, varying battery longevity, comorbidities, and care settings. The objective of this analysis was to compare changes in patient outcomes and payer costs attributable to increases in battery life of implantable cardiac defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-D). We developed a Monte Carlo Markov model simulation to follow patients through primary implant, postoperative maintenance, generator replacement, and revision states. Patients were simulated in 3-month increments for 15 years or until death. Key variables included Charlson Comorbidity Index, CIED type, legacy versus extended battery longevity, mortality rates (procedure and all-cause), infection and non-infectious complication rates, and care settings. Costs included procedure-related (facility and professional), maintenance, and infections and non-infectious complications, all derived from Medicare data (2004-2014, 5% sample). Outcomes included counts of battery replacements, revisions, infections and non-infectious complications, and discounted (3%) costs and life years. An increase in battery longevity in ICDs yielded reductions in numbers of revisions (by 23%), battery changes (by 44%), infections (by 23%), non-infectious complications (by 10%), and total costs per patient (by 9%). Analogous reductions for CRT-Ds were 23% (revisions), 32% (battery changes), 22% (infections), 8% (complications), and 10% (costs). Based on modeling results, as battery longevity increases, patients experience fewer adverse outcomes and healthcare costs are reduced. Understanding the magnitude of the cost benefit of extended battery life can inform budgeting and planning decisions by healthcare providers and insurers.

  10. Geometrical model for the electron

    International Nuclear Information System (INIS)

    El-Sherbini, T.M.

    1985-07-01

    A model for an electron of finite dimensions is proposed. This model disregards the concept of electronic charge and leads to Bohr's frequency formula for the hydrogen atom and to Maxwell's equations for electromagnetic fields. The stability of a free electron under the action of centrifugal and transverse forces is discussed. (author)

  11. Boltzmann electron PIC simulation of the E-sail effect

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2015-12-01

    Full Text Available The solar wind electric sail (E-sail is a planned in-space propulsion device that uses the natural solar wind momentum flux for spacecraft propulsion with the help of long, charged, centrifugally stretched tethers. The problem of accurately predicting the E-sail thrust is still somewhat open, however, due to a possible electron population trapped by the tether. Here we develop a new type of particle-in-cell (PIC simulation for predicting E-sail thrust. In the new simulation, electrons are modelled as a fluid, hence resembling hybrid simulation, but in contrast to normal hybrid simulation, the Poisson equation is used as in normal PIC to calculate the self-consistent electrostatic field. For electron-repulsive parts of the potential, the Boltzmann relation is used. For electron-attractive parts of the potential we employ a power law which contains a parameter that can be used to control the number of trapped electrons. We perform a set of runs varying the parameter and select the one with the smallest number of trapped electrons which still behaves in a physically meaningful way in the sense of producing not more than one solar wind ion deflection shock upstream of the tether. By this prescription we obtain thrust per tether length values that are in line with earlier estimates, although somewhat smaller. We conclude that the Boltzmann PIC simulation is a new tool for simulating the E-sail thrust. This tool enables us to calculate solutions rapidly and allows to easily study different scenarios for trapped electrons.

  12. Modeling and simulation of large HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Jin, H.; Sood, V.K.

    1993-01-01

    This paper addresses the complexity and the amount of work in preparing simulation data and in implementing various converter control schemes and the excessive simulation time involved in modelling and simulation of large HVDC systems. The Power Electronic Circuit Analysis program (PECAN) is used to address these problems and a large HVDC system with two dc links is simulated using PECAN. A benchmark HVDC system is studied to compare the simulation results with those from other packages. The simulation time and results are provided in the paper.

  13. Computer simulations of the random barrier model

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Dyre, Jeppe

    2002-01-01

    A brief review of experimental facts regarding ac electronic and ionic conduction in disordered solids is given followed by a discussion of what is perhaps the simplest realistic model, the random barrier model (symmetric hopping model). Results from large scale computer simulations are presented...

  14. Specs: Simulation Program for Electronic Circuits and Systems

    Science.gov (United States)

    de Geus, Aart Jan

    Simulation tools are central to the development and verification of very large scale integrated circuits. Circuit simulation has been used for over two decades to verify the behavior of designs. Recently the introduction of switch-level simulators which model MOS transistors in terms of switches has helped to overcome the long runtimes associated with full circuit simulation. Used strictly for functional verification and fault simulation, switch -level simulation can only give very rough estimates of the timing of a circuit. In this dissertation an approach is presented which adds a timing capability to switch-level simulators at relatively little extra CPU cost. A new logic state concept is introduced which consists of a set of discrete voltage steps. Signals are known only in terms of these states thus allowing all current computations to be table driven. State changes are scheduled in the same fashion as in the case of gate-level simulators, making the simulator event-driven. The simulator is of mixed-mode nature in that it can model portions of a design at either the gate or transistor level. In order to represent the "unknown" state, a signal consists of both an upper and a lower bound defining a signal envelope. Both bounds are expressed in terms of states. In order to speed up the simulation, MOS networks are subdivided in small pull-up and pull-down transistor configurations that can be preanalysed and prepared for fast evaluation during the simulation. These concepts have been implemented in the program SPECS (Simulation Program For Electronic Circuits and Systems) and examples of simulations are given.

  15. Model Comparison for Electron Thermal Transport

    Science.gov (United States)

    Moses, Gregory; Chenhall, Jeffrey; Cao, Duc; Delettrez, Jacques

    2015-11-01

    Four electron thermal transport models are compared for their ability to accurately and efficiently model non-local behavior in ICF simulations. Goncharov's transport model has accurately predicted shock timing in implosion simulations but is computationally slow and limited to 1D. The iSNB (implicit Schurtz Nicolai Busquet electron thermal transport method of Cao et al. uses multigroup diffusion to speed up the calculation. Chenhall has expanded upon the iSNB diffusion model to a higher order simplified P3 approximation and a Monte Carlo transport model, to bridge the gap between the iSNB and Goncharov models while maintaining computational efficiency. Comparisons of the above models for several test problems will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

  16. Simulation of loss electron in vacuum magnetically insulated transmission lines

    International Nuclear Information System (INIS)

    Zhang Pengfei; Li Yongdong; Liu Chunliang; Wang Hongguang; Guo Fan; Yang Hailiang; Qiu Aici; Su Zhaofeng; Sun Jianfeng; Sun Jiang; Gao Yi

    2011-01-01

    In the beginning of magnetic insulated period, loss electron in coaxial vacuum magnetically insulated transmission line (MITL) strikes anode and the bremsstrahlung photons are generated in the mean time. Based on the self-limited flow model, velocity in direction of energy transport, energy spectrum and angular distribution of loss electron are simulated by PIC code, energy spectrum of bremsstrahlung photons as well calculated though Monte Carlo method. Computational results show that the velocity of loss electron is less than 2.998 x 108 m/s, the angular excursion of electron is not much in a board extent of energy spectrum. These results show an indirect diagnosis of vacuum insulted transmission line working status based on loss electron bremsstrahlung. (authors)

  17. The Qualification of a large electron irradiation facility for telecommunication satellite differential charging simulation

    Science.gov (United States)

    Serene, B. E. H.; Reddy, J.

    1979-01-01

    The definition and procurement program is presented for the set up of a test simulating an electron environment on a model of a communication satellite to study the degradation of the thermal insulation materials during electron bombardment.

  18. Simulating electron clouds in heavy-ion accelerators

    International Nuclear Information System (INIS)

    Cohen, R.H.; Friedman, A.; Covo, M. Kireeff; Lund, S.M.; Molvik, A.W.; Bieniosek, F.M.; Seidl, P.A.; Vay, J.-L.; Stoltz, P.; Veitzer, S.

    2005-01-01

    Contaminating clouds of electrons are a concern for most accelerators of positively charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly magnetized, weakly magnetized, and unmagnetized. The approach to such self-consistency is described, and in particular a scheme for interpolating between full-orbit (Boris) and drift-kinetic particle pushes that enables electron time steps long compared to the typical gyroperiod in the magnets. Tests and applications are presented: simulation of electron clouds produced by three different kinds of sources indicates the sensitivity of the cloud shape to the nature of the source; first-of-a-kind self-consistent simulation of electron-cloud experiments on the high-current experiment [L. R. Prost, P. A. Seidl, F. M. Bieniosek, C. M. Celata, A. Faltens, D. Baca, E. Henestroza, J. W. Kwan, M. Leitner, W. L. Waldron, R. Cohen, A. Friedman, D. Grote, S. M. Lund, A. W. Molvik, and E. Morse, 'High current transport experiment for heavy ion inertial fusion', Physical Review Special Topics, Accelerators and Beams 8, 020101 (2005)], at Lawrence Berkeley National Laboratory, in which the machine can be flooded with electrons released by impact of the ion beam on an end plate, demonstrate the ability to reproduce key features of the ion-beam phase space; and simulation of a two-stream instability of thin beams in a magnetic field demonstrates the ability of the large-time-step mover to accurately calculate the instability

  19. Simulating Ru L3-edge X-ray absorption spectroscopy with time-dependent density functional theory: model complexes and electron localization in mixed-valence metal dimers.

    Science.gov (United States)

    Van Kuiken, Benjamin E; Valiev, Marat; Daifuku, Stephanie L; Bannan, Caitlin; Strader, Matthew L; Cho, Hana; Huse, Nils; Schoenlein, Robert W; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of Ru(II) and Ru(III) complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6](4-) and Ru(II) polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5M(II)-CN-Ru(III)(NH3)5](-) (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  20. Simulation - modeling - experiment

    International Nuclear Information System (INIS)

    2004-01-01

    After two workshops held in 2001 on the same topics, and in order to make a status of the advances in the domain of simulation and measurements, the main goals proposed for this workshop are: the presentation of the state-of-the-art of tools, methods and experiments in the domains of interest of the Gedepeon research group, the exchange of information about the possibilities of use of computer codes and facilities, about the understanding of physical and chemical phenomena, and about development and experiment needs. This document gathers 18 presentations (slides) among the 19 given at this workshop and dealing with: the deterministic and stochastic codes in reactor physics (Rimpault G.); MURE: an evolution code coupled with MCNP (Meplan O.); neutronic calculation of future reactors at EdF (Lecarpentier D.); advance status of the MCNP/TRIO-U neutronic/thermal-hydraulics coupling (Nuttin A.); the FLICA4/TRIPOLI4 thermal-hydraulics/neutronics coupling (Aniel S.); methods of disturbances and sensitivity analysis of nuclear data in reactor physics, application to VENUS-2 experimental reactor (Bidaud A.); modeling for the reliability improvement of an ADS accelerator (Biarotte J.L.); residual gas compensation of the space charge of intense beams (Ben Ismail A.); experimental determination and numerical modeling of phase equilibrium diagrams of interest in nuclear applications (Gachon J.C.); modeling of irradiation effects (Barbu A.); elastic limit and irradiation damage in Fe-Cr alloys: simulation and experiment (Pontikis V.); experimental measurements of spallation residues, comparison with Monte-Carlo simulation codes (Fallot M.); the spallation target-reactor coupling (Rimpault G.); tools and data (Grouiller J.P.); models in high energy transport codes: status and perspective (Leray S.); other ways of investigation for spallation (Audoin L.); neutrons and light particles production at intermediate energies (20-200 MeV) with iron, lead and uranium targets (Le Colley F

  1. Wake modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, G.C.; Aagaard Madsen, H.; Larsen, T.J.; Troldborg, N.

    2008-07-15

    We present a consistent, physically based theory for the wake meandering phenomenon, which we consider of crucial importance for the overall description of wind turbine loadings in wind farms. In its present version the model is confined to single wake situations. The model philosophy does, however, have the potential to include also mutual wake interaction phenomenons. The basic conjecture behind the dynamic wake meandering (DWM) model is that wake transportation in the atmospheric boundary layer is driven by the large scale lateral- and vertical turbulence components. Based on this conjecture a stochastic model of the downstream wake meandering is formulated. In addition to the kinematic formulation of the dynamics of the 'meandering frame of reference', models characterizing the mean wake deficit as well as the added wake turbulence, described in the meandering frame of reference, are an integrated part the DWM model complex. For design applications, the computational efficiency of wake deficit prediction is a key issue. A computationally low cost model is developed for this purpose. Likewise, the character of the added wake turbulence, generated by the up-stream turbine in the form of shed and trailed vorticity, has been approached by a simple semi-empirical model essentially based on an eddy viscosity philosophy. Contrary to previous attempts to model wake loading, the DWM approach opens for a unifying description in the sense that turbine power- and load aspects can be treated simultaneously. This capability is a direct and attractive consequence of the model being based on the underlying physical process, and it potentially opens for optimization of wind farm topology, of wind farm operation as well as of control strategies for the individual turbine. To establish an integrated modeling tool, the DWM methodology has been implemented in the aeroelastic code HAWC2, and example simulations of wake situations, from the small Tjaereborg wind farm, have

  2. Detailed Monte Carlo simulation of electron elastic scattering

    International Nuclear Information System (INIS)

    Chakarova, R.

    1994-04-01

    A detailed Monte Carlo model is described which simulates the transport of electrons penetrating a medium without energy loss. The trajectory of each electron is constructed as a series of successive interaction events - elastic or inelastic scattering. Differential elastic scattering cross sections, elastic and inelastic mean free paths are used to describe the interaction process. It is presumed that the cross sections data are available and the Monte Carlo algorithm does not include their evaluation. Electrons suffering successive elastic collisions are followed until they escape from the medium or (if the absorption is negligible) their path length exceeds a certain value. The inelastic events are thus treated as absorption. The medium geometry is a layered infinite slab. The electron source could be an incident electron beam or electrons created inside the material. The objective is to obtain the angular distribution, the path length and depth distribution and the collision number distribution of electrons emitted through the surface of the medium. The model is applied successfully to electrons with energy between 0.4 and 20 keV reflected from semi-infinite homogeneous materials with different scattering properties. 16 refs, 9 figs

  3. Biomolecular modelling and simulations

    CERN Document Server

    Karabencheva-Christova, Tatyana

    2014-01-01

    Published continuously since 1944, the Advances in Protein Chemistry and Structural Biology series is the essential resource for protein chemists. Each volume brings forth new information about protocols and analysis of proteins. Each thematically organized volume is guest edited by leading experts in a broad range of protein-related topics. Describes advances in biomolecular modelling and simulations Chapters are written by authorities in their field Targeted to a wide audience of researchers, specialists, and students The information provided in the volume is well supported by a number of high quality illustrations, figures, and tables.

  4. Communication: Relaxation-limited electronic currents in extended reservoir simulations

    Science.gov (United States)

    Gruss, Daniel; Smolyanitsky, Alex; Zwolak, Michael

    2017-10-01

    Open-system approaches are gaining traction in the simulation of charge transport in nanoscale and molecular electronic devices. In particular, "extended reservoir" simulations, where explicit reservoir degrees of freedom are present, allow for the computation of both real-time and steady-state properties but require relaxation of the extended reservoirs. The strength of this relaxation, γ, influences the conductance, giving rise to a "turnover" behavior analogous to Kramers turnover in chemical reaction rates. We derive explicit, general expressions for the weak and strong relaxation limits. For weak relaxation, the conductance increases linearly with γ and every electronic state of the total explicit system contributes to the electronic current according to its "reduced" weight in the two extended reservoir regions. Essentially, this represents two conductors in series—one at each interface with the implicit reservoirs that provide the relaxation. For strong relaxation, a "dual" expression-one with the same functional form-results, except now proportional to 1/γ and dependent on the system of interest's electronic states, reflecting that the strong relaxation is localizing electrons in the extended reservoirs. Higher order behavior (e.g., γ2 or 1/γ2) can occur when there is a gap in the frequency spectrum. Moreover, inhomogeneity in the frequency spacing can give rise to a pseudo-plateau regime. These findings yield a physically motivated approach to diagnosing numerical simulations and understanding the influence of relaxation, and we examine their occurrence in both simple models and a realistic, fluctuating graphene nanoribbon.

  5. Theory, modeling, and simulation annual report, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    This report briefly discusses research on the following topics: development of electronic structure methods; modeling molecular processes in clusters; modeling molecular processes in solution; modeling molecular processes in separations chemistry; modeling interfacial molecular processes; modeling molecular processes in the atmosphere; methods for periodic calculations on solids; chemistry and physics of minerals; graphical user interfaces for computational chemistry codes; visualization and analysis of molecular simulations; integrated computational chemistry environment; and benchmark computations.

  6. Electron conductivity model for dense plasmas

    International Nuclear Information System (INIS)

    Lee, Y.T.; More, R.M.

    1984-01-01

    An electron conductivity model for dense plasmas is described which gives a consistent and complete set of transport coefficients including not only electrical conductivity and thermal conductivity, but also thermoelectric power, and Hall, Nernst, Ettinghausen, and Leduc--Righi coefficients. The model is useful for simulating plasma experiments with strong magnetic fields. The coefficients apply over a wide range of plasma temperature and density and are expressed in a computationally simple form. Different formulas are used for the electron relaxation time in plasma, liquid, and solid phases. Comparisons with recent calculations and available experimental measurement show the model gives results which are sufficiently accurate for many practical applications

  7. Trapped electron decay by the thermally-assisted tunnelling to electron acceptors in glassy matrices. A computer simulation study

    International Nuclear Information System (INIS)

    Feret, B.; Bartczak, W.M.; Kroh, J.

    1991-01-01

    The Redi-Hopefield quantum mechanical model of the thermally-assisted electron transfer has been applied to simulate the decay of trapped electrons by tunnelling to electron acceptor molecules added to the glassy matrix. It was assumed that the electron energy levels in donors and acceptors are statistically distributed and the electron excess energy after transfer is dissipated in the medium by the electron-phonon coupling. The electron decay curves were obtained by the method of computer simulation. It was found that for a given medium there exists a certain preferred value of the electronic excess energy which can be effectively converted into the matrix vibrations. If the mismatch of the electron states on the donor and acceptor coincides with the ''resonance'' energy the overall kinetics of electron transfer is accelerated. (author)

  8. Analyses of experimental observations of electron temperatures in the near wake of a model in a laboratory-simulated solar wind plasma

    International Nuclear Information System (INIS)

    Intriligator, D.S.; Steele, G.R.

    1985-01-01

    Laboratory experiments have been performed that show the effect on the electron temperature of inserting a spherical conducting model, larger than the Debye length, into a free-streaming high-energy (1 kv) unmagnetized hydrogen plasma. These experiments are the first electron temperature experiments conducted at energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. The incident plasma parameters were held constant. A large number of axial profiles of the electron temperature ratios T/sub e//sub in// T/sub e//sub out/ behind the model downstream in the model wake are presented. A rigorous statistical approach is used in the analysis of the electron temperature ratio data in both our experimental laboratory data and in our reanalysis of the published data of others. The following new results ae obtained: (1) In energetic plasma flow there is no overall temperature enhancement in the near wake since the best fit to the T/sub e//sub i/n/ T/sub e//sub out/ data is a horizontal straight line having a mean value of 1.05; (2) No statistically significant electron temperature enhancement peaks or depressions exist in the near-wake region behind a model at zero potential in a high-energy plasma even at distances less than or equal to Ma, where M is the acoustic Mach number and a is the model radius. This implies a ''filling in'' of electrons in the wake region which may be due to the higher mobility of these energetic electrons. This mechanism may permit the solar wind electrons to significantly contribute to the maintenance of the nightside ionosphere at Venus

  9. Numerical simulation of transient moisture transfer into an electronic enclosure

    International Nuclear Information System (INIS)

    Nasirabadi, P. Shojaee; Jabbari, M.; Hattel, J. H.

    2016-01-01

    Electronic systems are sometimes exposed to harsh environmental conditions of temperature and humidity. Moisture transfer into electronic enclosures and condensation can cause several problems such as corrosion and alteration in thermal stresses. It is therefore essential to study the local climate inside the enclosures to be able to protect the electronic systems. In this work, moisture transfer into a typical electronic enclosure is numerically studied using CFD. In order to reduce the CPU-time and make a way for subsequent factorial design analysis, a simplifying modification is applied in which the real 3D geometry is approximated by a 2D axial symmetry one. The results for 2D and 3D models were compared in order to calibrate the 2D representation. Furthermore, simulation results were compared with experimental data and good agreement was found.

  10. Numerical simulation of transient moisture transfer into an electronic enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Nasirabadi, P. Shojaee; Jabbari, M.; Hattel, J. H. [Process Modelling Group, Department of Mechanical Engineering, Technical University of Denmark, Nils Koppels Allé, 2800 Kgs. Lyngby (Denmark)

    2016-06-08

    Electronic systems are sometimes exposed to harsh environmental conditions of temperature and humidity. Moisture transfer into electronic enclosures and condensation can cause several problems such as corrosion and alteration in thermal stresses. It is therefore essential to study the local climate inside the enclosures to be able to protect the electronic systems. In this work, moisture transfer into a typical electronic enclosure is numerically studied using CFD. In order to reduce the CPU-time and make a way for subsequent factorial design analysis, a simplifying modification is applied in which the real 3D geometry is approximated by a 2D axial symmetry one. The results for 2D and 3D models were compared in order to calibrate the 2D representation. Furthermore, simulation results were compared with experimental data and good agreement was found.

  11. CMS: Simulated Higgs to two jets and two electrons

    CERN Multimedia

    1997-01-01

    This track is an example of simulated data modelled for the CMS detector on the Large Hadron Collider (LHC) at CERN, which will begin taking data in 2008. Here a Higgs boson is produced which decays into two jets of hadrons and two electrons. The lines represent the possible paths of particles produced by the proton-proton collision in the detector while the energy these particles deposit is shown in blue.

  12. Numerical simulation methods for electron and ion optics

    International Nuclear Information System (INIS)

    Munro, Eric

    2011-01-01

    This paper summarizes currently used techniques for simulation and computer-aided design in electron and ion beam optics. Topics covered include: field computation, methods for computing optical properties (including Paraxial Rays and Aberration Integrals, Differential Algebra and Direct Ray Tracing), simulation of Coulomb interactions, space charge effects in electron and ion sources, tolerancing, wave optical simulations and optimization. Simulation examples are presented for multipole aberration correctors, Wien filter monochromators, imaging energy filters, magnetic prisms, general curved axis systems and electron mirrors.

  13. Theory and simulations of electron vortices generated by magnetic pushing

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, A. S.; Angus, J. R.; Swanekamp, S. B.; Schumer, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Ottinger, P. F. [An Independent Consultant through ENGILITY, Chantilly, Virginia 20151 (United States)

    2013-08-15

    Vortex formation and propagation are observed in kinetic particle-in-cell (PIC) simulations of magnetic pushing in the plasma opening switch. These vortices are studied here within the electron-magnetohydrodynamic (EMHD) approximation using detailed analytical modeling. PIC simulations of these vortices have also been performed. Strong v×B forces in the vortices give rise to significant charge separation, which necessitates the use of the EMHD approximation in which ions are fixed and the electrons are treated as a fluid. A semi-analytic model of the vortex structure is derived, and then used as an initial condition for PIC simulations. Density-gradient-dependent vortex propagation is then examined using a series of PIC simulations. It is found that the vortex propagation speed is proportional to the Hall speed v{sub Hall}≡cB{sub 0}/4πn{sub e}eL{sub n}. When ions are allowed to move, PIC simulations show that the electric field in the vortex can accelerate plasma ions, which leads to dissipation of the vortex. This electric field contributes to the separation of ion species that has been observed to occur in pulsed-power experiments with a plasma-opening switch.

  14. Electron-cloud simulation results for the SPS and recent results for the LHC

    International Nuclear Information System (INIS)

    Furman, M.A.; Pivi, M.T.F.

    2002-01-01

    We present an update of computer simulation results for some features of the electron cloud at the Large Hadron Collider (LHC) and recent simulation results for the Super Proton Synchrotron (SPS). We focus on the sensitivity of the power deposition on the LHC beam screen to the emitted electron spectrum, which we study by means of a refined secondary electron (SE) emission model recently included in our simulation code

  15. Energy-weighted dynamical scattering simulations of electron diffraction modalities in the scanning electron microscope.

    Science.gov (United States)

    Pascal, Elena; Singh, Saransh; Callahan, Patrick G; Hourahine, Ben; Trager-Cowan, Carol; Graef, Marc De

    2018-04-01

    Transmission Kikuchi diffraction (TKD) has been gaining momentum as a high resolution alternative to electron back-scattered diffraction (EBSD), adding to the existing electron diffraction modalities in the scanning electron microscope (SEM). The image simulation of any of these measurement techniques requires an energy dependent diffraction model for which, in turn, knowledge of electron energies and diffraction distances distributions is required. We identify the sample-detector geometry and the effect of inelastic events on the diffracting electron beam as the important factors to be considered when predicting these distributions. However, tractable models taking into account inelastic scattering explicitly are lacking. In this study, we expand the Monte Carlo (MC) energy-weighting dynamical simulations models used for EBSD [1] and ECP [2] to the TKD case. We show that the foil thickness in TKD can be used as a means of energy filtering and compare band sharpness in the different modalities. The current model is shown to correctly predict TKD patterns and, through the dictionary indexing approach, to produce higher quality indexed TKD maps than conventional Hough transform approach, especially close to grain boundaries. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Temperature dependence of the hydrated electron's excited-state relaxation. I. Simulation predictions of resonance Raman and pump-probe transient absorption spectra of cavity and non-cavity models

    Science.gov (United States)

    Zho, Chen-Chen; Farr, Erik P.; Glover, William J.; Schwartz, Benjamin J.

    2017-08-01

    We use one-electron non-adiabatic mixed quantum/classical simulations to explore the temperature dependence of both the ground-state structure and the excited-state relaxation dynamics of the hydrated electron. We compare the results for both the traditional cavity picture and a more recent non-cavity model of the hydrated electron and make definite predictions for distinguishing between the different possible structural models in future experiments. We find that the traditional cavity model shows no temperature-dependent change in structure at constant density, leading to a predicted resonance Raman spectrum that is essentially temperature-independent. In contrast, the non-cavity model predicts a blue-shift in the hydrated electron's resonance Raman O-H stretch with increasing temperature. The lack of a temperature-dependent ground-state structural change of the cavity model also leads to a prediction of little change with temperature of both the excited-state lifetime and hot ground-state cooling time of the hydrated electron following photoexcitation. This is in sharp contrast to the predictions of the non-cavity model, where both the excited-state lifetime and hot ground-state cooling time are expected to decrease significantly with increasing temperature. These simulation-based predictions should be directly testable by the results of future time-resolved photoelectron spectroscopy experiments. Finally, the temperature-dependent differences in predicted excited-state lifetime and hot ground-state cooling time of the two models also lead to different predicted pump-probe transient absorption spectroscopy of the hydrated electron as a function of temperature. We perform such experiments and describe them in Paper II [E. P. Farr et al., J. Chem. Phys. 147, 074504 (2017)], and find changes in the excited-state lifetime and hot ground-state cooling time with temperature that match well with the predictions of the non-cavity model. In particular, the experiments

  17. Computer Simulation of Electron Positron Annihilation Processes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, y

    2003-10-02

    With the launching of the Next Linear Collider coming closer and closer, there is a pressing need for physicists to develop a fully-integrated computer simulation of e{sup +}e{sup -} annihilation process at center-of-mass energy of 1TeV. A simulation program acts as the template for future experiments. Either new physics will be discovered, or current theoretical uncertainties will shrink due to more accurate higher-order radiative correction calculations. The existence of an efficient and accurate simulation will help us understand the new data and validate (or veto) some of the theoretical models developed to explain new physics. It should handle well interfaces between different sectors of physics, e.g., interactions happening at parton levels well above the QCD scale which are described by perturbative QCD, and interactions happening at much lower energy scale, which combine partons into hadrons. Also it should achieve competitive speed in real time when the complexity of the simulation increases. This thesis contributes some tools that will be useful for the development of such simulation programs. We begin our study by the development of a new Monte Carlo algorithm intended to perform efficiently in selecting weight-1 events when multiple parameter dimensions are strongly correlated. The algorithm first seeks to model the peaks of the distribution by features, adapting these features to the function using the EM algorithm. The representation of the distribution provided by these features is then improved using the VEGAS algorithm for the Monte Carlo integration. The two strategies mesh neatly into an effective multi-channel adaptive representation. We then present a new algorithm for the simulation of parton shower processes in high energy QCD. We want to find an algorithm which is free of negative weights, produces its output as a set of exclusive events, and whose total rate exactly matches the full Feynman amplitude calculation. Our strategy is to create

  18. Monte Carlo simulation of electron swarms in H2

    International Nuclear Information System (INIS)

    Hunter, S.R.

    1977-01-01

    A Monte Carlo simulation of the motion of an electron swarm in molecular hydrogen has been studied in the range E/N 1.4-170 Td. The simulation was performed for 400-600 electrons at several values of E/N for two different sets of inelastic collision cross sections at high E/N. Results were obtained for the longitudinal diffusion coefficient Dsub(L), lateral diffusion coefficient D, swarm drift velocity W, average swarm energy and ionization and excitation production coefficients, and these were compared with experimental data where available. It is found that the results differ significantly from the experimental values and this is attributed to the isotropic scattering model used in this work. However, the results lend support to the experimental technique used recently by Blevin et al. to determine these transport parameters, and in particular confirm their results that Dsub(L) > D at high values of E/N. (Author)

  19. Classical molecular dynamics simulation of electronically non-adiabatic processes.

    Science.gov (United States)

    Miller, William H; Cotton, Stephen J

    2016-12-22

    Both classical and quantum mechanics (as well as hybrids thereof, i.e., semiclassical approaches) find widespread use in simulating dynamical processes in molecular systems. For large chemical systems, however, which involve potential energy surfaces (PES) of general/arbitrary form, it is usually the case that only classical molecular dynamics (MD) approaches are feasible, and their use is thus ubiquitous nowadays, at least for chemical processes involving dynamics on a single PES (i.e., within a single Born-Oppenheimer electronic state). This paper reviews recent developments in an approach which extends standard classical MD methods to the treatment of electronically non-adiabatic processes, i.e., those that involve transitions between different electronic states. The approach treats nuclear and electronic degrees of freedom (DOF) equivalently (i.e., by classical mechanics, thereby retaining the simplicity of standard MD), and provides "quantization" of the electronic states through a symmetrical quasi-classical (SQC) windowing model. The approach is seen to be capable of treating extreme regimes of strong and weak coupling between the electronic states, as well as accurately describing coherence effects in the electronic DOF (including the de-coherence of such effects caused by coupling to the nuclear DOF). A survey of recent applications is presented to illustrate the performance of the approach. Also described is a newly developed variation on the original SQC model (found universally superior to the original) and a general extension of the SQC model to obtain the full electronic density matrix (at no additional cost/complexity).

  20. A computer code package for Monte Carlo photon-electron transport simulation Comparisons with experimental benchmarks

    International Nuclear Information System (INIS)

    Popescu, Lucretiu M.

    2000-01-01

    A computer code package (PTSIM) for particle transport Monte Carlo simulation was developed using object oriented techniques of design and programming. A flexible system for simulation of coupled photon, electron transport, facilitating development of efficient simulation applications, was obtained. For photons: Compton and photo-electric effects, pair production and Rayleigh interactions are simulated, while for electrons, a class II condensed history scheme was considered, in which catastrophic interactions (Moeller electron-electron interaction, bremsstrahlung, etc.) are treated in detail and all other interactions with reduced individual effect on electron history are grouped together using continuous slowing down approximation and energy straggling theories. Electron angular straggling is simulated using Moliere theory or a mixed model in which scatters at large angles are treated as distinct events. Comparisons with experimentally benchmarks for electron transmission and bremsstrahlung emissions energy and angular spectra, and for dose calculations are presented

  1. Monte Carlo simulation and experimental verification of radiotherapy electron beams

    International Nuclear Information System (INIS)

    Griffin, J.; Deloar, H. M.

    2007-01-01

    Full text: Based on fundamental physics and statistics, the Monte Carlo technique is generally accepted as the accurate method for modelling radiation therapy treatments. A Monte Carlo simulation system has been installed, and models of linear accelerators in the more commonly used electron beam modes have been built and commissioned. A novel technique for radiation dosimetry is also being investigated. Combining the advantages of both water tank and solid phantom dosimetry, a hollow, thin walled shell or mask is filled with water and then raised above the natural water surface to produce a volume of water with the desired irregular shape.

  2. Automated electronic intruder simulator for evaluation of ultrasonic intrusion detectors

    International Nuclear Information System (INIS)

    1979-01-01

    An automated electronic intruder simulator for testing ultrasonic intrusion detectors is described. This simulator is primarily intended for use in environmental chambers to determine the effects of temperature and humidity on the operation of ultrasonic intrusion detectors

  3. Notes on modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-10

    These notes present a high-level overview of how modeling and simulation are carried out by practitioners. The discussion is of a general nature; no specific techniques are examined but the activities associated with all modeling and simulation approaches are briefly addressed. There is also a discussion of validation and verification and, at the end, a section on why modeling and simulation are useful.

  4. Simulations and measurements in scanning electron microscopes at low electron energy

    Czech Academy of Sciences Publication Activity Database

    Walker, C.; Frank, Luděk; Müllerová, Ilona

    2016-01-01

    Roč. 38, č. 6 (2016), s. 802-818 ISSN 0161-0457 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 EU Projects: European Commission(XE) 606988 - SIMDALEE2 Institutional support: RVO:68081731 Keywords : Monte Carlo modeling * scanned probe * computer simulation * electron-solid interactions * surface analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.345, year: 2016

  5. Analytic model of electron pulse propagation in ultrafast electron diffraction experiments

    International Nuclear Information System (INIS)

    Michalik, A.M.; Sipe, J.E.

    2006-01-01

    We present a mean-field analytic model to study the propagation of electron pulses used in ultrafast electron diffraction experiments (UED). We assume a Gaussian form to characterize the electron pulse, and derive a system of ordinary differential equations that are solved quickly and easily to give the pulse dynamics. We compare our model to an N-body numerical simulation and are able to show excellent agreement between the two result sets. This model is a convenient alternative to time consuming and computationally intense N-body simulations in exploring the dynamics of UED electron pulses, and as a tool for refining UED experimental designs

  6. Xyce parallel electronic simulator : users' guide.

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Warrender, Christina E.; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2011-05-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers; (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) Device models which are specifically tailored to meet Sandia's needs, including some radiation-aware devices (for Sandia users only); and (4) Object-oriented code design and implementation using modern coding practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. Xyce is a parallel code in the most general sense of the phrase - a message passing parallel implementation - which allows it to run efficiently on the widest possible number of computing platforms. These include serial, shared-memory and distributed-memory parallel as well as heterogeneous platforms. Careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. The development of Xyce provides a platform for computational research and development aimed specifically at the needs of the Laboratory. With Xyce, Sandia has an 'in-house' capability with which both new electrical (e.g., device model development) and algorithmic (e.g., faster time-integration methods, parallel solver algorithms) research and development can be performed. As a result, Xyce is

  7. Numerical simulations of time-resolved quantum electronics

    International Nuclear Information System (INIS)

    Gaury, Benoit; Weston, Joseph; Santin, Matthieu; Houzet, Manuel; Groth, Christoph; Waintal, Xavier

    2014-01-01

    Numerical simulation has become a major tool in quantum electronics both for fundamental and applied purposes. While for a long time those simulations focused on stationary properties (e.g. DC currents), the recent experimental trend toward GHz frequencies and beyond has triggered a new interest for handling time-dependent perturbations. As the experimental frequencies get higher, it becomes possible to conceive experiments which are both time-resolved and fast enough to probe the internal quantum dynamics of the system. This paper discusses the technical aspects–mathematical and numerical–associated with the numerical simulations of such a setup in the time domain (i.e. beyond the single-frequency AC limit). After a short review of the state of the art, we develop a theoretical framework for the calculation of time-resolved observables in a general multiterminal system subject to an arbitrary time-dependent perturbation (oscillating electrostatic gates, voltage pulses, time-varying magnetic fields, etc.) The approach is mathematically equivalent to (i) the time-dependent scattering formalism, (ii) the time-resolved non-equilibrium Green’s function (NEGF) formalism and (iii) the partition-free approach. The central object of our theory is a wave function that obeys a simple Schrödinger equation with an additional source term that accounts for the electrons injected from the electrodes. The time-resolved observables (current, density, etc.) and the (inelastic) scattering matrix are simply expressed in terms of this wave function. We use our approach to develop a numerical technique for simulating time-resolved quantum transport. We find that the use of this wave function is advantageous for numerical simulations resulting in a speed up of many orders of magnitude with respect to the direct integration of NEGF equations. Our technique allows one to simulate realistic situations beyond simple models, a subject that was until now beyond the simulation

  8. Enamel dose calculation by electron paramagnetic resonance spectral simulation technique

    International Nuclear Information System (INIS)

    Dong Guofu; Cong Jianbo; Guo Linchao; Ning Jing; Xian Hong; Wang Changzhen; Wu Ke

    2011-01-01

    Objective: To optimize the enamel electron paramagnetic resonance (EPR) spectral processing by using the EPR spectral simulation method to improve the accuracy of enamel EPR dosimetry and reduce artificial error. Methods: The multi-component superimposed EPR powder spectral simulation software was developed to simulate EPR spectrum models of the background signal (BS) and the radiation- induced signal (RS) of irradiated enamel respectively. RS was extracted from the multi-component superimposed spectrum of irradiated enamel and its amplitude was calculated. The dose-response curve was then established for calculating the doses of a group of enamel samples. The result of estimated dose was compared with that calculated by traditional method. Results: BS was simulated as a powder spectrum of gaussian line shape with the following spectrum parameters: g=2.00 35 and Hpp=0.65-1.1 mT, RS signal was also simulated as a powder spectrum but with axi-symmetric spectrum characteristics. The spectrum parameters of RS were: g ⊥ =2.0018, g ‖ =1.9965, Hpp=0.335-0.4 mT. The amplitude of RS had a linear response to radiation dose with the regression equation as y=240.74x + 76 724 (R 2 =0.9947). The expectation of relative error of dose estimation was 0.13. Conclusions: EPR simulation method has improved somehow the accuracy and reliability of enamel EPR dose estimation. (authors)

  9. Numerical simulation of electron beam welding with beam oscillations

    Science.gov (United States)

    Trushnikov, D. N.; Permyakov, G. L.

    2017-02-01

    This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.

  10. Model Order Reduction for Electronic Circuits:

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Shontz, Suzanne

    Electronic circuits are ubiquitous; they are used in numerous industries including: the semiconductor, communication, robotics, auto, and music industries (among many others). As products become more and more complicated, their electronic circuits also grow in size and complexity. This increased...... in the semiconductor industry. Circuit simulation proceeds by using Maxwell’s equations to create a mathematical model of the circuit. The boundary element method is then used to discretize the equations, and the variational form of the equations are then solved on the graph network....

  11. A computer code package for electron transport Monte Carlo simulation

    International Nuclear Information System (INIS)

    Popescu, Lucretiu M.

    1999-01-01

    A computer code package was developed for solving various electron transport problems by Monte Carlo simulation. It is based on condensed history Monte Carlo algorithm. In order to get reliable results over wide ranges of electron energies and target atomic numbers, specific techniques of electron transport were implemented such as: Moliere multiscatter angular distributions, Blunck-Leisegang multiscatter energy distribution, sampling of electron-electron and Bremsstrahlung individual interactions. Path-length and lateral displacement corrections algorithms and the module for computing collision, radiative and total restricted stopping powers and ranges of electrons are also included. Comparisons of simulation results with experimental measurements are finally presented. (author)

  12. Simulation of the electron acoustic instability for a finite-size electron beam system

    International Nuclear Information System (INIS)

    Lin, C.S.; Winske, D.

    1987-01-01

    Satellite observations at midlatitudes (≅20,000 km) near the earth's dayside polar cusp boundary layer indicate that the upward electron beams have a narrow latitudinal width up to 0.1 0 . In the cusp boundary layer where the electron population consists of a finite-size electron beam in a background of uniform cold and hot electrons, the electron acoustic mode is unstable inside the electron beam but damped outside the electron beam. Simulations of the electron acoustic instability for a finite-size beam system are carried out with a particle-in-cell code to investigate the heating phenomena associated with the instability and the width of the heating region. The simulations show that the finite-size electron beam radiates electrostatic electron acoustic waves. The decay length of the electron acoustic waves outside the beam in the simulation agrees with the spatial decay length derived from the linear dispersion equation

  13. Simulation Model of a Transient

    DEFF Research Database (Denmark)

    Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte

    2005-01-01

    This paper describes the simulation model of a controller that enables an active-stall wind turbine to ride through transient faults. The simulated wind turbine is connected to a simple model of a power system. Certain fault scenarios are specified and the turbine shall be able to sustain operati...

  14. Cognitive models embedded in system simulation models

    International Nuclear Information System (INIS)

    Siegel, A.I.; Wolf, J.J.

    1982-01-01

    If we are to discuss and consider cognitive models, we must first come to grips with two questions: (1) What is cognition; (2) What is a model. Presumably, the answers to these questions can provide a basis for defining a cognitive model. Accordingly, this paper first places these two questions into perspective. Then, cognitive models are set within the context of computer simulation models and a number of computer simulations of cognitive processes are described. Finally, pervasive issues are discussed vis-a-vis cognitive modeling in the computer simulation context

  15. General introduction to simulation models

    DEFF Research Database (Denmark)

    Hisham Beshara Halasa, Tariq; Boklund, Anette

    2012-01-01

    trials. However, if simulation models would be used, good quality input data must be available. To model FMD, several disease spread models are available. For this project, we chose three simulation model; Davis Animal Disease Spread (DADS), that has been upgraded to DTU-DADS, InterSpread Plus (ISP......Monte Carlo simulation can be defined as a representation of real life systems to gain insight into their functions and to investigate the effects of alternative conditions or actions on the modeled system. Models are a simplification of a system. Most often, it is best to use experiments and field...... trials to investigate the effect of alternative conditions or actions on a specific system. Nonetheless, field trials are expensive and sometimes not possible to conduct, as in case of foot-and-mouth disease (FMD). Instead, simulation models can be a good and cheap substitute for experiments and field...

  16. Simulation - modeling - experiment; Simulation - modelisation - experience

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    After two workshops held in 2001 on the same topics, and in order to make a status of the advances in the domain of simulation and measurements, the main goals proposed for this workshop are: the presentation of the state-of-the-art of tools, methods and experiments in the domains of interest of the Gedepeon research group, the exchange of information about the possibilities of use of computer codes and facilities, about the understanding of physical and chemical phenomena, and about development and experiment needs. This document gathers 18 presentations (slides) among the 19 given at this workshop and dealing with: the deterministic and stochastic codes in reactor physics (Rimpault G.); MURE: an evolution code coupled with MCNP (Meplan O.); neutronic calculation of future reactors at EdF (Lecarpentier D.); advance status of the MCNP/TRIO-U neutronic/thermal-hydraulics coupling (Nuttin A.); the FLICA4/TRIPOLI4 thermal-hydraulics/neutronics coupling (Aniel S.); methods of disturbances and sensitivity analysis of nuclear data in reactor physics, application to VENUS-2 experimental reactor (Bidaud A.); modeling for the reliability improvement of an ADS accelerator (Biarotte J.L.); residual gas compensation of the space charge of intense beams (Ben Ismail A.); experimental determination and numerical modeling of phase equilibrium diagrams of interest in nuclear applications (Gachon J.C.); modeling of irradiation effects (Barbu A.); elastic limit and irradiation damage in Fe-Cr alloys: simulation and experiment (Pontikis V.); experimental measurements of spallation residues, comparison with Monte-Carlo simulation codes (Fallot M.); the spallation target-reactor coupling (Rimpault G.); tools and data (Grouiller J.P.); models in high energy transport codes: status and perspective (Leray S.); other ways of investigation for spallation (Audoin L.); neutrons and light particles production at intermediate energies (20-200 MeV) with iron, lead and uranium targets (Le Colley F

  17. Electron-cloud measurements and simulations for the APS

    International Nuclear Information System (INIS)

    Furman, M.A.; Pivi, M.; Harkay, K.C.; Rosenberg, R.A.

    2001-01-01

    We compare experimental results with simulations of the electron cloud effect induced by a positron beam at the APS synchrotron light source at ANL, where the electron cloud effect has been observed and measured with dedicated probes. We find good agreement between simulations and measurements for reasonable values of certain secondary electron yield (SEY) parameters, most of which were extracted from recent bench measurements at SLAC

  18. Phase-Space Models of Solitary Electron Hoies

    DEFF Research Database (Denmark)

    Lynov, Jens-Peter; Michelsen, Poul; Pécseli, Hans

    1985-01-01

    Two different phase-space models of solitary electron holes are investigated and compared with results from computer simulations of an actual laboratory experiment, carried out in a strongly magnetized, cylindrical plasma column. In the two models, the velocity distribution of the electrons...

  19. Simulation study on avoiding runaway electron generation by magnetic perturbations

    International Nuclear Information System (INIS)

    Tokuda, S.; Yoshino, R.; Matsumoto, T.; Hudson, S.R.; Kawano, Y.; Takizuka, T.

    2001-01-01

    Simulations have demonstrated that magnetic islands having the widths expected on the major disruption cause the collisionless loss of the relativistic electrons, and that the resultant loss rate is high enough to avoid or to suppress the runaway generation. It is because, for the magnetic fluctuations in the disruption, the loss of the electron confinement due to the breakdown of the toroidal momentum conservation overwhelms the runaway electron confinement due to the phase-averaging effect of relativistic electrons. Simulation results agree closely with recent experiments on fast plasma shutdown, showing that it is possible to prevent the generation of runaway electrons. (author)

  20. Simulation of the electron cloud density in BEPC II

    International Nuclear Information System (INIS)

    Liu Yudong; Guo Zhiyuan; Wang Jiuqing

    2004-01-01

    Electron Cloud Instability (ECI) may take place in positron storage ring when the machine is operated with multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPC II, a program has been developed. With the code, authors can calculate the electron density in the chamber with different length of antechamber and the different secondary electron yield respectively. By the simulation, the possibility to put clearing electrodes in the chamber to reduce the electron density in the central region of the chamber is investigated. The simulation provides meaningful and important results for the BEPC II project and electron cloud instability research

  1. Efficient and accurate simulations of two-dimensional electronic photon-echo signals: Illustration for a simple model of the Fenna-Matthews-Olson complex

    International Nuclear Information System (INIS)

    Sharp, Leah Z.; Egorova, Dassia; Domcke, Wolfgang

    2010-01-01

    Two-dimensional (2D) photon-echo spectra of a single subunit of the Fenna-Matthews-Olson (FMO) bacteriochlorophyll trimer of Chlorobium tepidum are simulated, employing the equation-of-motion phase-matching approach (EOM-PMA). We consider a slightly extended version of the previously proposed Frenkel exciton model, which explicitly accounts for exciton coherences in the secular approximation. The study is motivated by a recent experiment reporting long-lived coherent oscillations in 2D transients [Engel et al., Nature 446, 782 (2007)] and aims primarily at accurate simulations of the spectroscopic signals, with the focus on oscillations of 2D peak intensities with population time. The EOM-PMA accurately accounts for finite pulse durations as well as pulse-overlap effects and does not invoke approximations apart from the weak-field limit for a given material system. The population relaxation parameters of the exciton model are taken from the literature. The effects of various dephasing mechanisms on coherence lifetimes are thoroughly studied. It is found that the experimentally detected multiple frequencies in peak oscillations cannot be reproduced by the employed FMO model, which calls for the development of a more sophisticated exciton model of the FMO complex.

  2. Mechanistic electronic model to simulate and predict the effect of heat stress on the functional genomics of HO-1 system: Vasodilation.

    Science.gov (United States)

    Aggarwal, Yogender; Karan, Bhuwan Mohan; Das, Barda Nand; Sinha, Rakesh Kumar

    2010-05-01

    The present work is concerned to model the molecular signalling pathway for vasodilation and to predict the resting young human forearm blood flow under heat stress. The mechanistic electronic modelling technique has been designed and implemented using MULTISIM 8.0 and an assumption of 1V/ degrees C for prediction of forearm blood flow and the digital logic has been used to design the molecular signalling pathway for vasodilation. The minimum forearm blood flow has been observed at 35 degrees C (0 ml 100 ml(-1)min(-1)) and the maximum at 42 degrees C (18.7 ml 100 ml(-1)min(-1)) environmental temperature with respect to the base value of 2 ml 100 ml(-1)min(-1). This model may also enable to identify many therapeutic targets that can be used in the treatment of inflammations and disorders due to heat-related illnesses. 2010 Elsevier Ltd. All rights reserved.

  3. DNA strand breaks induced by electrons simulated with nanodosimetry Monte Carlo simulation code: NASIC

    International Nuclear Information System (INIS)

    Li, Junli; Qiu, Rui; Yan, Congchong; Xie, Wenzhang; Zeng, Zhi; Li, Chunyan; Wu, Zhen; Tung, Chuanjong

    2015-01-01

    The method of Monte Carlo simulation is a powerful tool to investigate the details of radiation biological damage at the molecular level. In this paper, a Monte Carlo code called NASIC (Nanodosimetry Monte Carlo Simulation Code) was developed. It includes physical module, pre-chemical module, chemical module, geometric module and DNA damage module. The physical module can simulate physical tracks of low-energy electrons in the liquid water event-by-event. More than one set of inelastic cross sections were calculated by applying the dielectric function method of Emfietzoglou's optical-data treatments, with different optical data sets and dispersion models. In the pre-chemical module, the ionised and excited water molecules undergo dissociation processes. In the chemical module, the produced radiolytic chemical species diffuse and react. In the geometric module, an atomic model of 46 chromatin fibres in a spherical nucleus of human lymphocyte was established. In the DNA damage module, the direct damages induced by the energy depositions of the electrons and the indirect damages induced by the radiolytic chemical species were calculated. The parameters should be adjusted to make the simulation results be agreed with the experimental results. In this paper, the influence study of the inelastic cross sections and vibrational excitation reaction on the parameters and the DNA strand break yields were studied. Further work of NASIC is underway (authors)

  4. The Electron Transport Chain: An Interactive Simulation

    Science.gov (United States)

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  5. ECONOMIC MODELING STOCKS CONTROL SYSTEM: SIMULATION MODEL

    OpenAIRE

    Климак, М.С.; Войтко, С.В.

    2016-01-01

    Considered theoretical and applied aspects of the development of simulation models to predictthe optimal development and production systems that create tangible products andservices. It isproved that theprocessof inventory control needs of economicandmathematical modeling in viewof thecomplexity of theoretical studies. A simulation model of stocks control that allows make managementdecisions with production logistics

  6. Progress in modeling and simulation.

    Science.gov (United States)

    Kindler, E

    1998-01-01

    For the modeling of systems, the computers are more and more used while the other "media" (including the human intellect) carrying the models are abandoned. For the modeling of knowledges, i.e. of more or less general concepts (possibly used to model systems composed of instances of such concepts), the object-oriented programming is nowadays widely used. For the modeling of processes existing and developing in the time, computer simulation is used, the results of which are often presented by means of animation (graphical pictures moving and changing in time). Unfortunately, the object-oriented programming tools are commonly not designed to be of a great use for simulation while the programming tools for simulation do not enable their users to apply the advantages of the object-oriented programming. Nevertheless, there are exclusions enabling to use general concepts represented at a computer, for constructing simulation models and for their easy modification. They are described in the present paper, together with true definitions of modeling, simulation and object-oriented programming (including cases that do not satisfy the definitions but are dangerous to introduce misunderstanding), an outline of their applications and of their further development. In relation to the fact that computing systems are being introduced to be control components into a large spectrum of (technological, social and biological) systems, the attention is oriented to models of systems containing modeling components.

  7. Xyce Parallel Electronic Simulator Reference Guide Version 6.4

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schiek, Richard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Verley, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Baur, David Gregory [Raytheon, Albuquerque, NM (United States)

    2015-12-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users' Guide [1] . The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce . This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users' Guide [1] . Trademarks The information herein is subject to change without notice. Copyright c 2002-2015 Sandia Corporation. All rights reserved. Xyce TM Electronic Simulator and Xyce TM are trademarks of Sandia Corporation. Portions of the Xyce TM code are: Copyright c 2002, The Regents of the University of California. Produced at the Lawrence Livermore National Laboratory. Written by Alan Hindmarsh, Allan Taylor, Radu Serban. UCRL-CODE-2002-59 All rights reserved. Orcad, Orcad Capture, PSpice and Probe are registered trademarks of Cadence Design Systems, Inc. Microsoft, Windows and Windows 7 are registered trademarks of Microsoft Corporation. Medici, DaVinci and Taurus are registered trademarks of Synopsys Corporation. Amtec and TecPlot are trademarks of Amtec Engineering, Inc. Xyce 's expression library is based on that inside Spice 3F5 developed by the EECS Department at the University of California. The EKV3 MOSFET model was developed by the EKV Team of the Electronics Laboratory-TUC of the Technical University of Crete. All other trademarks are property of their respective owners. Contacts Bug Reports (Sandia only) http://joseki.sandia.gov/bugzilla http://charleston.sandia.gov/bugzilla World Wide Web http://xyce.sandia.gov http://charleston.sandia.gov/xyce (Sandia only) Email xyce@sandia.gov (outside Sandia) xyce-sandia@sandia.gov (Sandia only)

  8. Particle-in-cell Simulations with Kinetic Electrons

    International Nuclear Information System (INIS)

    Lewandowski, J.L.V.

    2004-01-01

    A new scheme, based on an exact separation between adiabatic and nonadiabatic electron responses, for particle-in-cell (PIC) simulations of drift-type modes is presented. The (linear and nonlinear) elliptic equations for the scalar fields are solved using a multi-grid solver. The new scheme yields linear growth rates in excellent agreement with theory and it is shown to conserve energy well into the nonlinear regime. It is also demonstrated that simulations with few electrons are reliable and accurate, suggesting that large-scale, PIC simulations with electron dynamics in toroidal geometry (e.g., tokamaks and stellarators plasmas) are within reach of present-day massively parallel supercomputers

  9. PIC simulation of the electron-ion collision effects on suprathermal electrons

    International Nuclear Information System (INIS)

    Wu Yanqing; Han Shensheng

    2000-01-01

    The generation and transportation of suprathermal electrons are important to both traditional ICF scheme and 'Fast Ignition' scheme. The author discusses the effects of electron-ion collision on the generation and transportation of the suprathermal electrons by parametric instability. It indicates that the weak electron-ion term in the PIC simulation results in the enhancement of the collisional absorption and increase of the hot electron temperature and reduction in the maximum electrostatic field amplitude while wave breaking. Therefore the energy and distribution of the suprathermal electrons are changed. They are distributed more close to the phase velocity of the electrostatic wave than the case without electron-ion collision term. The electron-ion collision enhances the self-consistent field and impedes the suprathermal electron transportation. These factors also reduce the suprathermal electron energy. In addition, the authors discuss the effect of initial condition on PIC simulation to ensure that the results are correct

  10. Xyce Parallel Electronic Simulator Reference Guide Version 6.6.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aadithya, Karthik Venkatraman [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schiek, Richard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Verley, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users' Guide [1] . The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce . This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users' Guide [1] . The information herein is subject to change without notice. Copyright c 2002-2016 Sandia Corporation. All rights reserved. Acknowledgements The BSIM Group at the University of California, Berkeley developed the BSIM3, BSIM4, BSIM6, BSIM-CMG and BSIM-SOI models. The BSIM3 is Copyright c 1999, Regents of the University of California. The BSIM4 is Copyright c 2006, Regents of the University of California. The BSIM6 is Copyright c 2015, Regents of the University of California. The BSIM-CMG is Copyright c 2012 and 2016, Regents of the University of California. The BSIM-SOI is Copyright c 1990, Regents of the University of California. All rights reserved. The Mextram model has been developed by NXP Semiconductors until 2007, Delft University of Technology from 2007 to 2014, and Auburn University since April 2015. Copyrights c of Mextram are with Delft University of Technology, NXP Semiconductors and Auburn University. The MIT VS Model Research Group developed the MIT Virtual Source (MVS) model. Copyright c 2013 Massachusetts Institute of Technology (MIT). The EKV3 MOSFET model was developed by the EKV Team of the Electronics Laboratory-TUC of the Technical University of Crete. Trademarks Xyce TM Electronic Simulator and Xyce TM are trademarks of Sandia Corporation. Orcad, Orcad Capture, PSpice and Probe are registered trademarks of Cadence Design Systems, Inc. Microsoft, Windows and Windows 7 are registered trademarks of Microsoft Corporation. Medici, DaVinci and Taurus are registered trademarks of Synopsys Corporation. Amtec and Tec

  11. Resistorless Electronically Tunable Grounded Inductance Simulator Design

    OpenAIRE

    Herencsár, Norbert; Kartci, Aslihan

    2017-01-01

    A new realization of grounded lossless positive inductance simulator (PIS) using simple inverting voltage buffer and unity-gain current follower/inverter (CF±) is reported. Considering the input intrinsic resistance of CF± as useful active parameter, the proposed PIS can be considered as resistorless circuit and it only employs in total 16 Metal-Oxide-Semiconductor (MOS) transistors and a grounded capacitor. The resulting equivalent inductance value of the proposed simulator can be adjusted v...

  12. Electron cloud effects: codes and simulations at KEK

    International Nuclear Information System (INIS)

    Ohmi, K

    2013-01-01

    Electron cloud effects had been studied at KEK-Photon Factory since 1995. e-p instability had been studied in proton rings since 1965 in BINP, ISR and PSR. Study of electron cloud effects with the present style, which was based on numerical simulations, started at 1995 in positron storage rings. The instability observed in KEKPF gave a strong impact to B factories, KEKB and PEPII, which were final stage of their design in those days. History of cure for electron cloud instability overlapped the progress of luminosity performance in KEKB. The studies on electron cloud codes and simulations in KEK are presented. (author)

  13. Stochastic modeling analysis and simulation

    CERN Document Server

    Nelson, Barry L

    1995-01-01

    A coherent introduction to the techniques for modeling dynamic stochastic systems, this volume also offers a guide to the mathematical, numerical, and simulation tools of systems analysis. Suitable for advanced undergraduates and graduate-level industrial engineers and management science majors, it proposes modeling systems in terms of their simulation, regardless of whether simulation is employed for analysis. Beginning with a view of the conditions that permit a mathematical-numerical analysis, the text explores Poisson and renewal processes, Markov chains in discrete and continuous time, se

  14. Simulation study of secondary electron images in scanning ion microscopy

    CERN Document Server

    Ohya, K

    2003-01-01

    The target atomic number, Z sub 2 , dependence of secondary electron yield is simulated by applying a Monte Carlo code for 17 species of metals bombarded by Ga ions and electrons in order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM). In addition to the remarkable reversal of the Z sub 2 dependence between the Ga ion and electron bombardment, a fine structure, which is correlated to the density of the conduction band electrons in the metal, is calculated for both. The brightness changes of the secondary electron images in SIM and SEM are simulated using Au and Al surfaces adjacent to each other. The results indicate that the image contrast in SIM is much more sensitive to the material species and is clearer than that for SEM. The origin of the difference between SIM and SEM comes from the difference in the lateral distribution of secondary electrons excited within the escape depth.

  15. FASTBUS simulation models in VHDL

    International Nuclear Information System (INIS)

    Appelquist, G.

    1992-11-01

    Four hardware simulation models implementing the FASTBUS protocol are described. The models are written in the VHDL hardware description language to obtain portability, i.e. without relations to any specific simulator. They include two complete FASTBUS devices, a full-duplex segment interconnect and ancillary logic for the segment. In addition, master and slave models using a high level interface to describe FASTBUS operations, are presented. With these models different configurations of FASTBUS systems can be evaluated and the FASTBUS transactions of new devices can be verified. (au)

  16. Model reduction for circuit simulation

    CERN Document Server

    Hinze, Michael; Maten, E Jan W Ter

    2011-01-01

    Simulation based on mathematical models plays a major role in computer aided design of integrated circuits (ICs). Decreasing structure sizes, increasing packing densities and driving frequencies require the use of refined mathematical models, and to take into account secondary, parasitic effects. This leads to very high dimensional problems which nowadays require simulation times too large for the short time-to-market demands in industry. Modern Model Order Reduction (MOR) techniques present a way out of this dilemma in providing surrogate models which keep the main characteristics of the devi

  17. Greenhouse simulation models.

    NARCIS (Netherlands)

    Bot, G.P.A.

    1989-01-01

    A model is a representation of a real system to describe some properties i.e. internal factors of that system (out-puts) as function of some external factors (inputs). It is impossible to describe the relation between all internal factors (if even all internal factors could be defined) and all

  18. New Temperature-Insensitive Electronically-Tunable Grounded Capacitor Simulator

    OpenAIRE

    Abuelma'atti, Muhammad Taher; Khan, Muhammad Haroon

    1996-01-01

    A new circuit for simulating a grounded capacitor is presented. The circuit uses one operationalamplifier (OA), three operational-transconductance amplifiers (OTAs), and one capacitor. The realized capacitor is temperature-insensitive and electronically tunable. Experimental results are included.

  19. Monte Carlo simulation of electron swarms in H2

    International Nuclear Information System (INIS)

    Hunter, S.R.

    1976-05-01

    A Monte-Carlo simulation of the motion of an electron swarm in molecular hydrogen was studied in the range E/N = 1.4-170 Td (1 Td = 10 -17 V/cms 2 ). The simulation was performed for 400-600 electrons at several values of E/N for two different sets of inelastic collision cross sections at high values of E/N. The longitudinal diffusion coefficient Dsub(L), lateral diffusion coefficient D, swarm drift velocity W, average swarm energy epsilon, and the ionization and excitation production coefficients were obtained and compared with experimental results where these are available. It was found that the results obtained differ significantly from the experimental values and this is attributed to the isotopic scattering model used in this work. However, the results lend support to the experimental technique reported by Blevin et al used to determine these transport parameters, and in particular confirm their result that Dsub(L) > D at high values of E/N. (author)

  20. Electron Holography Image Simulation of Nanoparticles

    NARCIS (Netherlands)

    Keimpema, K.; Raedt, H. De; Hosson, J.Th.M. De

    We discuss a real-space and a Fourier-space technique to compute numerically, the phase images observed by electron holography of nanoscale particles. An assessment of the applicability and accuracy of these techniques is made by calculating numerical results for simple geometries for which

  1. Simplified models for the Monte Carlo simulation of energy distributions of keV electrons transmitted or back-scattered in various solids

    International Nuclear Information System (INIS)

    Liljequist, D.

    1978-01-01

    Simplified models, based on stopping power, transport mean free path and classical straggling, are shown to give results in rather good agreement with experiment and comparable with the results of more detailed, direct Monte Carlo procedure hitherto constructed. The small effects of features such as large-angle scattering and the interaction between straggling and scattering are studied. A description based on the near linearity of the transport mean free path is used to obtain empirical corrections in some cases of the total transmission and back-scattering simulation and empirical estimates of the (Bethe) range and the transport mean free path. The estimates of the range are consistent with a rough calculation of the effect of large binding energies. (author)

  2. A VRLA battery simulation model

    International Nuclear Information System (INIS)

    Pascoe, Phillip E.; Anbuky, Adnan H.

    2004-01-01

    A valve regulated lead acid (VRLA) battery simulation model is an invaluable tool for the standby power system engineer. The obvious use for such a model is to allow the assessment of battery performance. This may involve determining the influence of cells suffering from state of health (SOH) degradation on the performance of the entire string, or the running of test scenarios to ascertain the most suitable battery size for the application. In addition, it enables the engineer to assess the performance of the overall power system. This includes, for example, running test scenarios to determine the benefits of various load shedding schemes. It also allows the assessment of other power system components, either for determining their requirements and/or vulnerabilities. Finally, a VRLA battery simulation model is vital as a stand alone tool for educational purposes. Despite the fundamentals of the VRLA battery having been established for over 100 years, its operating behaviour is often poorly understood. An accurate simulation model enables the engineer to gain a better understanding of VRLA battery behaviour. A system level multipurpose VRLA battery simulation model is presented. It allows an arbitrary battery (capacity, SOH, number of cells and number of strings) to be simulated under arbitrary operating conditions (discharge rate, ambient temperature, end voltage, charge rate and initial state of charge). The model accurately reflects the VRLA battery discharge and recharge behaviour. This includes the complex start of discharge region known as the coup de fouet

  3. Electron and ion heating by whistler turbulence: Three-dimensional particle-in-cell simulations

    International Nuclear Information System (INIS)

    Hughes, R. Scott; Gary, S. Peter; Wang, Joseph

    2014-01-01

    Three-dimensional particle-in-cell simulations of decaying whistler turbulence are carried out on a collisionless, homogeneous, magnetized, electron-ion plasma model. In addition, the simulations use an initial ensemble of relatively long wavelength whistler modes with a broad range of initial propagation directions with an initial electron beta β e = 0.05. The computations follow the temporal evolution of the fluctuations as they cascade into broadband turbulent spectra at shorter wavelengths. Three simulations correspond to successively larger simulation boxes and successively longer wavelengths of the initial fluctuations. The computations confirm previous results showing electron heating is preferentially parallel to the background magnetic field B o , and ion heating is preferentially perpendicular to B o . The new results here are that larger simulation boxes and longer initial whistler wavelengths yield weaker overall dissipation, consistent with linear dispersion theory predictions of decreased damping, stronger ion heating, consistent with a stronger ion Landau resonance, and weaker electron heating

  4. Sensitivity Analysis of Simulation Models

    NARCIS (Netherlands)

    Kleijnen, J.P.C.

    2009-01-01

    This contribution presents an overview of sensitivity analysis of simulation models, including the estimation of gradients. It covers classic designs and their corresponding (meta)models; namely, resolution-III designs including fractional-factorial two-level designs for first-order polynomial

  5. Computer Based Modelling and Simulation

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 3. Computer Based Modelling and Simulation - Modelling Deterministic Systems. N K Srinivasan. General Article Volume 6 Issue 3 March 2001 pp 46-54. Fulltext. Click here to view fulltext PDF. Permanent link:

  6. Modeling the Nab Experiment Electronics in SPICE

    Science.gov (United States)

    Blose, Alexander; Crawford, Christopher; Sprow, Aaron; Nab Collaboration

    2017-09-01

    The goal of the Nab experiment is to measure the neutron decay coefficients a, the electron-neutrino correlation, as well as b, the Fierz interference term to precisely test the Standard Model, as well as probe for Beyond the Standard Model physics. In this experiment, protons from the beta decay of the neutron are guided through a magnetic field into a Silicon detector. Event reconstruction will be achieved via time-of-flight measurement for the proton and direct measurement of the coincident electron energy in highly segmented silicon detectors, so the amplification circuitry needs to preserve fast timing, provide good amplitude resolution, and be packaged in a high-density format. We have designed a SPICE simulation to model the full electronics chain for the Nab experiment in order to understand the contributions of each stage and optimize them for performance. Additionally, analytic solutions to each of the components have been determined where available. We will present a comparison of the output from the SPICE model, analytic solution, and empirically determined data.

  7. Monte Carlo Simulation of Electron Transport in 4H- and 6H-SiC

    International Nuclear Information System (INIS)

    Sun, C. C.; You, A. H.; Wong, E. K.

    2010-01-01

    The Monte Carlo (MC) simulation of electron transport properties at high electric field region in 4H- and 6H-SiC are presented. This MC model includes two non-parabolic conduction bands. Based on the material parameters, the electron scattering rates included polar optical phonon scattering, optical phonon scattering and acoustic phonon scattering are evaluated. The electron drift velocity, energy and free flight time are simulated as a function of applied electric field at an impurity concentration of 1x10 18 cm 3 in room temperature. The simulated drift velocity with electric field dependencies is in a good agreement with experimental results found in literature. The saturation velocities for both polytypes are close, but the scattering rates are much more pronounced for 6H-SiC. Our simulation model clearly shows complete electron transport properties in 4H- and 6H-SiC.

  8. Two-dimensional simulation research of secondary electron emission avalanche discharge on vacuum insulator surface

    Science.gov (United States)

    Cai, Libing; Wang, Jianguo; Zhu, Xiangqin; Wang, Yue; Zhang, Dianhui

    2015-01-01

    Based on the secondary electron emission avalanche (SEEA) model, the SEEA discharge on the vacuum insulator surface is simulated by using a 2D PIC-MCC code developed by ourselves. The evolutions of the number of discharge electrons, insulator surface charge, current, and 2D particle distribution are obtained. The effects of the strength of the applied electric field, secondary electron yield coefficient, rise time of the pulse, length of the insulator on the discharge are investigated. The results show that the number of the SEEA electrons presents a quadratic dependence upon the applied field strength. The SEEA current, which is on the order of Ampere, is directly proportional to the field strength and secondary electron yield coefficient. Finally, the electron-stimulated outgassing is included in the simulation code, and a three-phase discharge curve is presented by the simulation, which agrees with the experimental data.

  9. Two-dimensional simulation research of secondary electron emission avalanche discharge on vacuum insulator surface

    International Nuclear Information System (INIS)

    Cai, Libing; Wang, Jianguo; Zhu, Xiangqin; Wang, Yue; Zhang, Dianhui

    2015-01-01

    Based on the secondary electron emission avalanche (SEEA) model, the SEEA discharge on the vacuum insulator surface is simulated by using a 2D PIC-MCC code developed by ourselves. The evolutions of the number of discharge electrons, insulator surface charge, current, and 2D particle distribution are obtained. The effects of the strength of the applied electric field, secondary electron yield coefficient, rise time of the pulse, length of the insulator on the discharge are investigated. The results show that the number of the SEEA electrons presents a quadratic dependence upon the applied field strength. The SEEA current, which is on the order of Ampere, is directly proportional to the field strength and secondary electron yield coefficient. Finally, the electron-stimulated outgassing is included in the simulation code, and a three-phase discharge curve is presented by the simulation, which agrees with the experimental data

  10. Geant4-DNA simulation of electron slowing-down spectra in liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Incerti, S., E-mail: sebastien.incerti@tdt.edu.vn [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Univ. Bordeaux, CENBG, UMR 5797, F-33170, Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Kyriakou, I. [Medical Physics Laboratory, University of Ioannina Medical School, 45110 Ioannina (Greece); Tran, H.N. [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam)

    2017-04-15

    This work presents the simulation of monoenergetic electron slowing-down spectra in liquid water by the Geant4-DNA extension of the Geant4 Monte Carlo toolkit (release 10.2p01). These spectra are simulated for several incident energies using the most recent Geant4-DNA physics models, and they are compared to literature data. The influence of Auger electron production is discussed. For the first time, a dedicated Geant4-DNA example allowing such simulations is described and is provided to Geant4 users, allowing further verification of Geant4-DNA track structure simulation capabilities.

  11. The portability of the "Electronics Workbench" simulation software to China

    NARCIS (Netherlands)

    Collis, Betty; Zhi-Cheng, Dong

    1993-01-01

    This article discusses the portability of the Canadian-made simulation software package, "Electronic Workbench" package (EWB) to China. As part of a larger project investigating the portability of various educational software packages, the EWB package was used in electronics instruction in China and

  12. Molecular dynamics simulation of the first electron transfer step in the oxygen reduction reaction

    NARCIS (Netherlands)

    Hartnig, C.B.; Koper, M.T.M.

    2002-01-01

    We present a molecular dynamics simulation of solvent reorganization in the first electron transfer step in the oxygen reduction reaction, i.e. O2+e-¿O2-, modeled as taking place in the outer Helmholtz plane. The first electron transfer step is usually considered the rate-determining step from many

  13. Efficacy of Simulation-Based Learning of Electronics Using Visualization and Manipulation

    Science.gov (United States)

    Chen, Yu-Lung; Hong, Yu-Ru; Sung, Yao-Ting; Chang, Kuo-En

    2011-01-01

    Software for simulation-based learning of electronics was implemented to help learners understand complex and abstract concepts through observing external representations and exploring concept models. The software comprises modules for visualization and simulative manipulation. Differences in learning performance of using the learning software…

  14. Optimisation of 12 MeV electron beam simulation using variance reduction technique

    International Nuclear Information System (INIS)

    Jayamani, J; Aziz, M Z Abdul; Termizi, N A S Mohd; Kamarulzaman, F N Mohd

    2017-01-01

    Monte Carlo (MC) simulation for electron beam radiotherapy consumes a long computation time. An algorithm called variance reduction technique (VRT) in MC was implemented to speed up this duration. This work focused on optimisation of VRT parameter which refers to electron range rejection and particle history. EGSnrc MC source code was used to simulate (BEAMnrc code) and validate (DOSXYZnrc code) the Siemens Primus linear accelerator model with the non-VRT parameter. The validated MC model simulation was repeated by applying VRT parameter (electron range rejection) that controlled by global electron cut-off energy 1,2 and 5 MeV using 20 × 10 7 particle history. 5 MeV range rejection generated the fastest MC simulation with 50% reduction in computation time compared to non-VRT simulation. Thus, 5 MeV electron range rejection utilized in particle history analysis ranged from 7.5 × 10 7 to 20 × 10 7 . In this study, 5 MeV electron cut-off with 10 × 10 7 particle history, the simulation was four times faster than non-VRT calculation with 1% deviation. Proper understanding and use of VRT can significantly reduce MC electron beam calculation duration at the same time preserving its accuracy. (paper)

  15. Simulation studies on stability of hot electron plasma

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu

    1985-01-01

    Stability of a hot electron plasma in an NBT(EBT)-like geometry is studied by using a 2-1/2 dimensional relativistic, electromagnetic particle code. For the low-frequency hot electron interchange mode, comparison of the simulation results with the analytical predictions of linear stability theory show fairly good agreement with the magnitude of the growth rates calculated without hot electron finite Larmor radius effects. Strong stabilizing effects by finite Larmor radius of the hot electrons are observed for short wavelength modes. As for the high-frequency hot electron interchange mode, there is a discrepancy between the simulation results and the theory. The high-frequency instability is not observed though a parameter regime is chosen in which the high-frequency hot electron interchange mode is theoretically predicted to grow. Strong cross-field diffusion in a poloidal direction of the hot electrons might explain the stability. Each particle has a magnetic drift velocity, and the speed of the magnetic drift is proportional to the kinetic energy of each particle. Hence, if the particles have high temperature, the spread of the magnetic drift velocity is large. This causes a strong cross-field diffusion of the hot electrons. In the simulation for this interchange mode, an enhanced temperature relaxation is observed between the hot and cold electrons although the theoretically predicted high frequency modes are stable. (Nogami, K.)

  16. Lessons on electronic decoherence in molecules from exact modeling

    Science.gov (United States)

    Hu, Wenxiang; Gu, Bing; Franco, Ignacio

    2018-04-01

    Electronic decoherence processes in molecules and materials are usually thought and modeled via schemes for the system-bath evolution in which the bath is treated either implicitly or approximately. Here we present computations of the electronic decoherence dynamics of a model many-body molecular system described by the Su-Schrieffer-Heeger Hamiltonian with Hubbard electron-electron interactions using an exact method in which both electronic and nuclear degrees of freedom are taken into account explicitly and fully quantum mechanically. To represent the electron-nuclear Hamiltonian in matrix form and propagate the dynamics, the computations employ the Jordan-Wigner transformation for the fermionic creation/annihilation operators and the discrete variable representation for the nuclear operators. The simulations offer a standard for electronic decoherence that can be used to test approximations. They also provide a useful platform to answer fundamental questions about electronic decoherence that cannot be addressed through approximate or implicit schemes. Specifically, through simulations, we isolate basic mechanisms for electronic coherence loss and demonstrate that electronic decoherence is possible even for one-dimensional nuclear bath. Furthermore, we show that (i) decreasing the mass of the bath generally leads to faster electronic decoherence; (ii) electron-electron interactions strongly affect the electronic decoherence when the electron-nuclear dynamics is not pure-dephasing; (iii) classical bath models with initial conditions sampled from the Wigner distribution accurately capture the short-time electronic decoherence dynamics; (iv) model separable initial superpositions often used to understand decoherence after photoexcitation are only relevant in experiments that employ delta-like laser pulses to initiate the dynamics. These insights can be employed to interpret and properly model coherence phenomena in molecules.

  17. Vehicle dynamics modeling and simulation

    CERN Document Server

    Schramm, Dieter; Bardini, Roberto

    2014-01-01

    The authors examine in detail the fundamentals and mathematical descriptions of the dynamics of automobiles. In this context different levels of complexity will be presented, starting with basic single-track models up to complex three-dimensional multi-body models. A particular focus is on the process of establishing mathematical models on the basis of real cars and the validation of simulation results. The methods presented are explained in detail by means of selected application scenarios.

  18. Ultrafast equilibration of excited electrons in dynamical simulations.

    Science.gov (United States)

    Lin, Zhibin; Allen, Roland E

    2009-12-02

    In our density-functional-based simulations of materials responding to femtosecond-scale laser pulses, we have observed a potentially useful phenomenon: the excited electrons automatically equilibrate to a Fermi-Dirac distribution within ∼100 fs, solely because of their coupling to the nuclear motion, even though the resulting electronic temperature is one to two orders of magnitude higher than the kinetic temperature defined by the nuclear motion. Microscopic simulations like these can then provide the separate electronic and kinetic temperatures, chemical potentials, pressures, and nonhydrostatic stresses as input for studies on larger lengths and timescales.

  19. Numerical simulation of Higgs models

    International Nuclear Information System (INIS)

    Jaster, A.

    1995-10-01

    The SU(2) Higgs and the Schwinger model on the lattice were analysed. Numerical simulations of the SU(2) Higgs model were performed to study the finite temperature electroweak phase transition. With the help of the multicanonical method the distribution of an order parameter at the phase transition point was measured. This was used to obtain the order of the phase transition and the value of the interface tension with the histogram method. Numerical simulations were also performed at zero temperature to perform renormalization. The measured values for the Wilson loops were used to determine the static potential and from this the renormalized gauge coupling. The Schwinger model was simulated at different gauge couplings to analyse the properties of the Kaplan-Shamir fermions. The prediction that the mass parameter gets only multiplicative renormalization was tested and verified. (orig.)

  20. Parallelizing an electron transport Monte Carlo simulator (MOCASIN 2.0)

    International Nuclear Information System (INIS)

    Schwetman, H.; Burdick, S.

    1988-01-01

    Electron transport simulators are tools for studying electrical properties of semiconducting materials and devices. As demands for modeling more complex devices and new materials have emerged, so have demands for more processing power. This paper documents a project to convert an electron transport simulator (MOCASIN 2.0) to a parallel processing environment. In addition to describing the conversion, the paper presents PPL, a parallel programming version of C running on a Sequent multiprocessor system. In timing tests, models that simulated the movement of 2,000 particles for 100 time steps were executed on ten processors, with a parallel efficiency of over 97%

  1. Stochastic models: theory and simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Field, Richard V., Jr.

    2008-03-01

    Many problems in applied science and engineering involve physical phenomena that behave randomly in time and/or space. Examples are diverse and include turbulent flow over an aircraft wing, Earth climatology, material microstructure, and the financial markets. Mathematical models for these random phenomena are referred to as stochastic processes and/or random fields, and Monte Carlo simulation is the only general-purpose tool for solving problems of this type. The use of Monte Carlo simulation requires methods and algorithms to generate samples of the appropriate stochastic model; these samples then become inputs and/or boundary conditions to established deterministic simulation codes. While numerous algorithms and tools currently exist to generate samples of simple random variables and vectors, no cohesive simulation tool yet exists for generating samples of stochastic processes and/or random fields. There are two objectives of this report. First, we provide some theoretical background on stochastic processes and random fields that can be used to model phenomena that are random in space and/or time. Second, we provide simple algorithms that can be used to generate independent samples of general stochastic models. The theory and simulation of random variables and vectors is also reviewed for completeness.

  2. Electron-plasmon model in the electron liquid theory

    Directory of Open Access Journals (Sweden)

    M.V.Vavrukh

    2005-01-01

    Full Text Available Here we propose an accurate approach to the description of the electron liquid model in the electron and plasmon terms. Our ideas in the present paper are close to the conception of the collective variables which was developed in the papers of Bohm and Pines. However we use another body of mathematics in the transition to the expanded space of variable particles and plasmons realized by the transition operator. It is evident that in the Random Phase Approximation (RPA, the model which consists of two interactive subsystems of electrons and plasmons is equivalent to the electron liquid model with Coulomb interaction.

  3. Plasma modelling and numerical simulation

    International Nuclear Information System (INIS)

    Van Dijk, J; Kroesen, G M W; Bogaerts, A

    2009-01-01

    Plasma modelling is an exciting subject in which virtually all physical disciplines are represented. Plasma models combine the electromagnetic, statistical and fluid dynamical theories that have their roots in the 19th century with the modern insights concerning the structure of matter that were developed throughout the 20th century. The present cluster issue consists of 20 invited contributions, which are representative of the state of the art in plasma modelling and numerical simulation. These contributions provide an in-depth discussion of the major theories and modelling and simulation strategies, and their applications to contemporary plasma-based technologies. In this editorial review, we introduce and complement those papers by providing a bird's eye perspective on plasma modelling and discussing the historical context in which it has surfaced. (editorial review)

  4. Xyce Parallel Electronic Simulator Users Guide Version 6.2.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R.; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Sholander, Peter E.; Thornquist, Heidi K.; Verley, Jason C.; Baur, David Gregory

    2014-09-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been de- signed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: Capability to solve extremely large circuit problems by supporting large-scale parallel com- puting platforms (up to thousands of processors). This includes support for most popular parallel and serial computers. A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models. Device models that are specifically tailored to meet Sandia's needs, including some radiation- aware devices (for Sandia users only). Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase -- a message passing parallel implementation -- which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. Trademarks The information herein is subject to change without notice. Copyright c 2002-2014 Sandia Corporation. All rights reserved. Xyce TM Electronic Simulator and Xyce TM are trademarks of Sandia Corporation. Portions of the Xyce TM code are: Copyright c 2002, The Regents of the University of California. Produced at the Lawrence Livermore National Laboratory. Written by Alan Hindmarsh, Allan Taylor, Radu Serban. UCRL-CODE-2002-59 All rights reserved. Orcad, Orcad Capture, PSpice and Probe are

  5. Xyce Parallel Electronic Simulator Users Guide Version 6.4

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schiek, Richard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Verley, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Baur, David Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been de- signed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: Capability to solve extremely large circuit problems by supporting large-scale parallel com- puting platforms (up to thousands of processors). This includes support for most popular parallel and serial computers. A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models. Device models that are specifically tailored to meet Sandia's needs, including some radiation- aware devices (for Sandia users only). Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase -- a message passing parallel implementation -- which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. Trademarks The information herein is subject to change without notice. Copyright c 2002-2015 Sandia Corporation. All rights reserved. Xyce TM Electronic Simulator and Xyce TM are trademarks of Sandia Corporation. Portions of the Xyce TM code are: Copyright c 2002, The Regents of the University of California. Produced at the Lawrence Livermore National Laboratory. Written by Alan Hindmarsh, Allan Taylor, Radu Serban. UCRL-CODE-2002-59 All rights reserved. Orcad, Orcad Capture, PSpice and Probe are

  6. Simulation studies of plasma waves in the electron foreshock - The generation of Langmuir waves by a gentle bump-on-tail electron distribution

    Science.gov (United States)

    Dum, C. T.

    1990-01-01

    Particle simulation experiments were used to study the basic physical ingredients needed for building a global model of foreshock wave phenomena. In particular, the generation of Langmuir waves by a gentle bump-on-tail electron distribution is analyzed. It is shown that, with appropriately designed simulations experiments, quasi-linear theory can be quantitatively verified for parameters corresponding to the electron foreshock.

  7. Electron-cloud updated simulation results for the PSR, and recent results for the SNS

    International Nuclear Information System (INIS)

    Pivi, M.; Furman, M.A.

    2002-01-01

    Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code

  8. Quantitative Test of the Evolution of Geant4 Electron Backscattering Simulation

    CERN Document Server

    Basaglia, Tullio; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Sung Hun; Pia, Maria Grazia; Saracco, Paolo

    2016-01-01

    Evolutions of Geant4 code have affected the simulation of electron backscattering with respect to previously published results. Their effects are quantified by analyzing the compatibility of the simulated electron backscattering fraction with a large collection of experimental data for a wide set of physics configuration options available in Geant4. Special emphasis is placed on two electron scattering implementations first released in Geant4 version 10.2: the Goudsmit-Saunderson multiple scattering model and a single Coulomb scattering model based on Mott cross section calculation. The new Goudsmit-Saunderson multiple scattering model appears to perform equally or less accurately than the model implemented in previous Geant4 versions, depending on the electron energy. The new Coulomb scattering model was flawed from a physics point of view, but computationally fast in Geant4 version 10.2; the physics correction released in Geant4 version 10.2p01 severely degrades its computational performance. Evolutions in ...

  9. Model for Simulation Atmospheric Turbulence

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik

    1976-01-01

    A method that produces realistic simulations of atmospheric turbulence is developed and analyzed. The procedure makes use of a generalized spectral analysis, often called a proper orthogonal decomposition or the Karhunen-Loève expansion. A set of criteria, emphasizing a realistic appearance...... eigenfunctions and estimates of the distributions of the corresponding expansion coefficients. The simulation method utilizes the eigenfunction expansion procedure to produce preliminary time histories of the three velocity components simultaneously. As a final step, a spectral shaping procedure is then applied....... The method is unique in modeling the three velocity components simultaneously, and it is found that important cross-statistical features are reasonably well-behaved. It is concluded that the model provides a practical, operational simulator of atmospheric turbulence....

  10. Gravitational Reference Sensor Front-End Electronics Simulator for LISA

    International Nuclear Information System (INIS)

    Meshksar, Neda; Ferraioli, Luigi; Mance, Davor; Zweifel, Peter; Giardini, Domenico; Ten Pierick, Jan

    2017-01-01

    At the ETH Zurich we are developing a modular simulator that provides a realistic simulation of the Front End Electronics (FEE) for LISA Gravitational Reference Sensor (GRS). It is based on the GRS FEE-simulator already implemented for LISA Pathfinder. It considers, in particular, the non-linearity and the critical details of hardware, such as the non-linear multiplicative noise caused by voltage reference instability, test mass charging and detailed actuation and sensing algorithms. We present the simulation modules, considering the above-mentioned features. Based on the ETH GRS FEE-simulator for LISA Pathfinder we aim to develop a modular simulator that provides a realistic simulation of GRS FEE for LISA. (paper)

  11. Comparison of electron cloud simulation and experiments in the high-current experiment

    International Nuclear Information System (INIS)

    Cohen, R.H.; Friedman, A.; Covo, M. Kireeff; Lund, S.M.; Molvik, A.W.; Bieniosek, F.M.; Seidl, P.A.; Vay, J.-L.; Verboncoeur, J.; Stoltz, P.; Veitzer, S.

    2004-01-01

    A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability

  12. Spectral line shape simulation for electron stark-broadening of ion emitters in plasmas

    International Nuclear Information System (INIS)

    Dufour, Emmanuelle; Calisti, Annette; Talin, Bernard; Gigosos, Marco A.; Gonzalez, Manuel A.; Dufty, Jim W.

    2002-01-01

    Electron broadening for ions in plasmas is investigated in the framework of a simplified semi-classical model involving an ionic emitter imbedded in an electron gas. A regularized Coulomb potential that removes the divergence at short distances is postulated for the ion-electron interaction. Line shape simulations based on Molecular Dynamics for the ion impurity and the electrons, accounting for all the correlations, are reported. Comparisons with line shapes obtained with a quasi-particle model show expected correlation effects. Through an analysis of the results with the line shape code PPP, it is inferred that the correlation effect results mainly from the microfield dynamic properties

  13. Monte-Carlo simulations of secondary electron emission from CsI, induced by 1-10 keV X-rays and electrons

    International Nuclear Information System (INIS)

    Akkerman, A.; Gibrekhterman, A.; Breskin, A.; Chechik, R.

    1992-05-01

    A model for electron transport and emission in CsI is proposed. It is based on theoretically calculated microscopic cross-sections for electron interaction with the nuclear and the electronic components of the solid. A Monte Carlo program based on this model was developed to simulate secondary electron emission induced by X-rays and electrons in the energy range of 1 to 10 keV. The calculated secondary emission yields agree with existing experimental data. The model provides all necessary characteristics for the design of radiation detectors based on secondary electron emission. It can be expanded to higher incident energies and other alkali halides. (author)

  14. Backscattered electron emission after proton impact on carbon and gold films: Experiments and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hespeels, F.; Heuskin, A.C. [University of Namur, PMR, 61 rue de Bruxelles, B-5000 Namur (Belgium); Scifoni, E. [TIFPA-INFN, Trento Institute for Fundamental Physics and Applications, Via Sommarive 14, I-38123 Trento (Italy); GSI-Helmholtzzentrum für Schwerionenforschung, Biophysik, Max Planck-Strasse 1, D-64291 Darmstadt (Germany); Kraemer, M. [GSI-Helmholtzzentrum für Schwerionenforschung, Biophysik, Max Planck-Strasse 1, D-64291 Darmstadt (Germany); Lucas, S., E-mail: stephane.lucas@unamur.be [University of Namur, PMR, 61 rue de Bruxelles, B-5000 Namur (Belgium)

    2017-06-15

    This work aims at measuring the proton induced secondary electron energy spectra from nanometer thin films. Backscattered electron energy spectra were measured within an energy range from 0 to 600 eV using a Retarding Field Analyser (RFA). This paper presents energy spectra obtained for proton (0.5 MeV; 1 MeV; 1.5 MeV; 2 MeV) irradiation of thin carbon films (50 and 100 nm thick) and thin gold film (200 nm). These experimental spectra were compared with Monte Carlo simulations based on TRAX code and Geant4 simulation toolkit. Good agreement between experimental, TRAX and Geant4 results were observed for the carbon target. For the gold target, we report major differences between both Monte Carlo environments. Limitation of Geant4 models for low energy electron emission was highlighted. On the contrary, TRAX simulations present encouraging results for the modeling of low-energy electron emission from gold target.

  15. Molecular dynamics simulation of electron trapping in the sapphire lattice

    International Nuclear Information System (INIS)

    Rambaut, C.; Oh, K.H.; Fayeulle, S.; Kohanoff, J.

    1995-10-01

    Energy storage and release in dielectric materials can be described on the basis of the charge trapping mechanism. Most phenomenological aspects have been recently rationalized in terms of the space charge mode. Dynamical aspects are studied here by performing Molecular Dynamics simulations. We show that an excess electron introduced into the sapphire lattice (α -Al 2 O 3 ) can be trapped only at a limited number of sites. The energy gained by allowing the electron to localize in these sites is of the order of 4-5 eV, in good agreement with the results of the space charge model. Displacements of the neighboring ions due to the implanted charge are shown to be localized in a small region of about 5 A. Detrapping is observed at 250 K. The ionic displacements turn out to play an important role in modifying the potential landscape by lowering, in a dynamical way, the barriers that cause localization at low temperature. (author). 18 refs, 7 figs, 2 tabs

  16. Validation process of simulation model

    International Nuclear Information System (INIS)

    San Isidro, M. J.

    1998-01-01

    It is presented a methodology on empirical validation about any detailed simulation model. This king of validation it is always related with an experimental case. The empirical validation has a residual sense, because the conclusions are based on comparisons between simulated outputs and experimental measurements. This methodology will guide us to detect the fails of the simulation model. Furthermore, it can be used a guide in the design of posterior experiments. Three steps can be well differentiated: Sensitivity analysis. It can be made with a DSA, differential sensitivity analysis, and with a MCSA, Monte-Carlo sensitivity analysis. Looking the optimal domains of the input parameters. It has been developed a procedure based on the Monte-Carlo methods and Cluster techniques, to find the optimal domains of these parameters. Residual analysis. This analysis has been made on the time domain and on the frequency domain, it has been used the correlation analysis and spectral analysis. As application of this methodology, it is presented the validation carried out on a thermal simulation model on buildings, Esp., studying the behavior of building components on a Test Cell of LECE of CIEMAT. (Author) 17 refs

  17. Modeling and Simulation for Safeguards

    International Nuclear Information System (INIS)

    Swinhoe, Martyn T.

    2012-01-01

    The purpose of this talk is to give an overview of the role of modeling and simulation in Safeguards R and D and introduce you to (some of) the tools used. Some definitions are: (1) Modeling - the representation, often mathematical, of a process, concept, or operation of a system, often implemented by a computer program; (2) Simulation - the representation of the behavior or characteristics of one system through the use of another system, especially a computer program designed for the purpose; and (3) Safeguards - the timely detection of diversion of significant quantities of nuclear material. The role of modeling and simulation are: (1) Calculate amounts of material (plant modeling); (2) Calculate signatures of nuclear material etc. (source terms); and (3) Detector performance (radiation transport and detection). Plant modeling software (e.g. FACSIM) gives the flows and amount of material stored at all parts of the process. In safeguards this allow us to calculate the expected uncertainty of the mass and evaluate the expected MUF. We can determine the measurement accuracy required to achieve a certain performance.

  18. Modeling and Simulation of Nanoindentation

    Science.gov (United States)

    Huang, Sixie; Zhou, Caizhi

    2017-11-01

    Nanoindentation is a hardness test method applied to small volumes of material which can provide some unique effects and spark many related research activities. To fully understand the phenomena observed during nanoindentation tests, modeling and simulation methods have been developed to predict the mechanical response of materials during nanoindentation. However, challenges remain with those computational approaches, because of their length scale, predictive capability, and accuracy. This article reviews recent progress and challenges for modeling and simulation of nanoindentation, including an overview of molecular dynamics, the quasicontinuum method, discrete dislocation dynamics, and the crystal plasticity finite element method, and discusses how to integrate multiscale modeling approaches seamlessly with experimental studies to understand the length-scale effects and microstructure evolution during nanoindentation tests, creating a unique opportunity to establish new calibration procedures for the nanoindentation technique.

  19. Simulations for a compact electron-positron spectrometer

    International Nuclear Information System (INIS)

    Filep, T.; Krasznahorkay, A.; Csatlos, M.; Gulyas, J.

    2011-01-01

    Complete text of publication follows. In the frame of the ENSAR (FP7) project, we are constructing a Compact Positron- Electron spectrometer (COPE) using toroidal magnetic field. It will be used for studying the internal pair creation process in nuclear transitions. It will look like a miniaturized model of the ATLAS spectrometer at CERN at a scale of 1:100. The mean design parameters are high efficiency, good energy resolution and precise angle reconstruction. By our plans the size of this spectrometer would be limited to a diameter of about 30 cm and length about 20 cm, having 1 % energy- and 2deg angular resolutions. The solid angle of the planned spectrometer will be 2π. It is necessary to develop a geometry in which the inhomogeneity of the field can be easily handled. Prior to the construction it was necessary to perform computer simulations in order to avoid rough construction mistakes. The better approach of the reality with simulations is very important. The problem what we have to solve is very complicated. We need to simulate the magnetic field and trajectory of the particle moving in that field. We started our simulations using the PerMag software package. >From the result we learned the followings: 1) It has no meaning to cover the magnets with iron coat because it complicates the magnetic field. 2) It is not a good idea to form the magnetic one-segment from a big magnet and 12 smaller magnets. The fringing field of the small magnets significantly modifies the magnetic field distribution around the segment. On the other hand the construction of one segment from pieces is very difficult in reality. 3) The best shape for a segment which can easily be constructed is simple box. The PerMag package could simulate the magnetic field only in 2D, but we wanted to do more precise simulation in 3D. The free package developed by the European Synchrotron Radiation Facility (ESRF) was used for the simulation of the magnetic field applying the finite element method

  20. Plasma simulation studies using multilevel physics models

    International Nuclear Information System (INIS)

    Park, W.; Belova, E.V.; Fu, G.Y.; Tang, X.Z.; Strauss, H.R.; Sugiyama, L.E.

    1999-01-01

    The question of how to proceed toward ever more realistic plasma simulation studies using ever increasing computing power is addressed. The answer presented here is the M3D (Multilevel 3D) project, which has developed a code package with a hierarchy of physics levels that resolve increasingly complete subsets of phase-spaces and are thus increasingly more realistic. The rationale for the multilevel physics models is given. Each physics level is described and examples of its application are given. The existing physics levels are fluid models (3D configuration space), namely magnetohydrodynamic (MHD) and two-fluids; and hybrid models, namely gyrokinetic-energetic-particle/MHD (5D energetic particle phase-space), gyrokinetic-particle-ion/fluid-electron (5D ion phase-space), and full-kinetic-particle-ion/fluid-electron level (6D ion phase-space). Resolving electron phase-space (5D or 6D) remains a future project. Phase-space-fluid models are not used in favor of δf particle models. A practical and accurate nonlinear fluid closure for noncollisional plasmas seems not likely in the near future. copyright 1999 American Institute of Physics

  1. Plasma simulation studies using multilevel physics models

    International Nuclear Information System (INIS)

    Park, W.; Belova, E.V.; Fu, G.Y.

    2000-01-01

    The question of how to proceed toward ever more realistic plasma simulation studies using ever increasing computing power is addressed. The answer presented here is the M3D (Multilevel 3D) project, which has developed a code package with a hierarchy of physics levels that resolve increasingly complete subsets of phase-spaces and are thus increasingly more realistic. The rationale for the multilevel physics models is given. Each physics level is described and examples of its application are given. The existing physics levels are fluid models (3D configuration space), namely magnetohydrodynamic (MHD) and two-fluids; and hybrid models, namely gyrokinetic-energetic-particle/MHD (5D energetic particle phase-space), gyrokinetic-particle-ion/fluid-electron (5D ion phase-space), and full-kinetic-particle-ion/fluid-electron level (6D ion phase-space). Resolving electron phase-space (5D or 6D) remains a future project. Phase-space-fluid models are not used in favor of delta f particle models. A practical and accurate nonlinear fluid closure for noncollisional plasmas seems not likely in the near future

  2. Electron Cloud Simulations of a Proton Storage Ring Using Cold Proton Bunches

    International Nuclear Information System (INIS)

    Sato, Y.; Holmes, Jeffrey A.; Lee, S.Y.; Macek, R.

    2008-01-01

    Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs the bunch charge and the recovery of electron clouds after sweeping on the beam loss rate and the SEY. The simulation results are compared with the experimental data measured at the proton storage ring at the Los Alamos National Laboratory. Our simulations indicate that the fractional proton loss rate in the field-free straight section may be an exponential function of proton beam charge and may also be lower than the averaged fractional proton loss rate over the whole ring.

  3. Novel simulation method of space charge effects in electron optical systems including emission of electrons

    Czech Academy of Sciences Publication Activity Database

    Zelinka, Jiří; Oral, Martin; Radlička, Tomáš

    2018-01-01

    Roč. 184, JAN (2018), s. 66-76 ISSN 0304-3991 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : space charge * self-consistent simulation * aberration polynomial * electron emission Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.843, year: 2016

  4. Numerical simulations of the thermionic electron gun for electron-beam welding and micromachining

    Czech Academy of Sciences Publication Activity Database

    Jánský, Pavel; Zlámal, J.; Lencová, Bohumila; Zobač, Martin; Vlček, Ivan; Radlička, Tomáš

    2009-01-01

    Roč. 84, č. 2 (2009), s. 357-362 ISSN 0042-207X R&D Projects: GA AV ČR IAA100650805 Institutional research plan: CEZ:AV0Z20650511 Keywords : Numerical simulation * Thermionic emission * Electron gun Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.975, year: 2009

  5. Assessment of Molecular Modeling & Simulation

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-01-03

    This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes.

  6. NRTA simulation by modeling PFPF

    International Nuclear Information System (INIS)

    Asano, Takashi; Fujiwara, Shigeo; Takahashi, Saburo; Shibata, Junichi; Totsu, Noriko

    2003-01-01

    In PFPF, NRTA system has been applied since 1991. It has been confirmed by evaluating facility material accountancy data provided from operator in each IIV that a significant MUF was not generated. In case of throughput of PFPF scale, MUF can be evaluated with a sufficient detection probability by the present NRTA evaluation manner. However, by increasing of throughput, the uncertainty of material accountancy will increase, and the detection probability will decline. The relationship between increasing of throughput and declining of detection probability and the maximum throughput upon application of following measures with a sufficient detection probability were evaluated by simulation of NRTA system. This simulation was performed by modeling of PFPF. Measures for increasing detection probability are shown as follows. Shortening of the evaluation interval. Segmentation of evaluation area. This report shows the results of these simulations. (author)

  7. Molecular modeling and multiscaling issues for electronic material applications

    CERN Document Server

    Iwamoto, Nancy; Yuen, Matthew; Fan, Haibo

    Volume 1 : Molecular Modeling and Multiscaling Issues for Electronic Material Applications provides a snapshot on the progression of molecular modeling in the electronics industry and how molecular modeling is currently being used to understand material performance to solve relevant issues in this field. This book is intended to introduce the reader to the evolving role of molecular modeling, especially seen through the eyes of the IEEE community involved in material modeling for electronic applications.  Part I presents  the role that quantum mechanics can play in performance prediction, such as properties dependent upon electronic structure, but also shows examples how molecular models may be used in performance diagnostics, especially when chemistry is part of the performance issue.  Part II gives examples of large-scale atomistic methods in material failure and shows several examples of transitioning between grain boundary simulations (on the atomistic level)and large-scale models including an example ...

  8. Vlasov fluid model with electron pressure

    International Nuclear Information System (INIS)

    Gerwin, R.

    1975-11-01

    The Vlasov-ion, fluid-electron model of Freidberg for studying the linear stability of hot-ion pinch configurations is here extended to include electron pressure. Within the framework of an adiabatic electron-gas picture, it is shown that this model is still amenable to the numerical methods described by Lewis and Freidberg

  9. Xyce parallel electronic simulator reference guide, version 6.1

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Sholander, Peter E.; Thornquist, Heidi K.; Verley, Jason C.; Baur, David Gregory

    2014-03-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users Guide [1] . The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users Guide [1] .

  10. Xyce™ Parallel Electronic Simulator: Reference Guide, Version 5.1

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Rankin, Eric Lamont [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Schiek, Richard Louis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Santarelli, Keith R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Fixel, Deborah A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical and Microsystems Modeling; Coffey, Todd S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Applied Mathematics and Applications; Pawlowski, Roger P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Applied Mathematics and Applications

    2009-11-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users’ Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users’ Guide.

  11. Xyce Parallel Electronic Simulator : reference guide, version 4.1.

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2009-02-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users Guide.

  12. Xyce™ Parallel Electronic Simulator Reference Guide Version 6.8

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aadithya, Karthik Venkatraman [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schiek, Richard L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Verley, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-10-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users' Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce . This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users' Guide.

  13. Xyce parallel electronic simulator reference guide, version 6.0.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Thornquist, Heidi K.; Verley, Jason C.; Fixel, Deborah A.; Coffey, Todd S; Pawlowski, Roger P; Warrender, Christina E.; Baur, David Gregory.

    2013-08-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users Guide [1] . The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users Guide [1] .

  14. Repository simulation model: Final report

    International Nuclear Information System (INIS)

    1988-03-01

    This report documents the application of computer simulation for the design analysis of the nuclear waste repository's waste handling and packaging operations. The Salt Repository Simulation Model was used to evaluate design alternatives during the conceptual design phase of the Salt Repository Project. Code development and verification was performed by the Office of Nuclear Waste Isolation (ONWL). The focus of this report is to relate the experience gained during the development and application of the Salt Repository Simulation Model to future repository design phases. Design of the repository's waste handling and packaging systems will require sophisticated analysis tools to evaluate complex operational and logistical design alternatives. Selection of these design alternatives in the Advanced Conceptual Design (ACD) and License Application Design (LAD) phases must be supported by analysis to demonstrate that the repository design will cost effectively meet DOE's mandated emplacement schedule and that uncertainties in the performance of the repository's systems have been objectively evaluated. Computer simulation of repository operations will provide future repository designers with data and insights that no other analytical form of analysis can provide. 6 refs., 10 figs

  15. Simulating spin models on GPU

    Science.gov (United States)

    Weigel, Martin

    2011-09-01

    Over the last couple of years it has been realized that the vast computational power of graphics processing units (GPUs) could be harvested for purposes other than the video game industry. This power, which at least nominally exceeds that of current CPUs by large factors, results from the relative simplicity of the GPU architectures as compared to CPUs, combined with a large number of parallel processing units on a single chip. To benefit from this setup for general computing purposes, the problems at hand need to be prepared in a way to profit from the inherent parallelism and hierarchical structure of memory accesses. In this contribution I discuss the performance potential for simulating spin models, such as the Ising model, on GPU as compared to conventional simulations on CPU.

  16. Standard for Models and Simulations

    Science.gov (United States)

    Steele, Martin J.

    2016-01-01

    This NASA Technical Standard establishes uniform practices in modeling and simulation to ensure essential requirements are applied to the design, development, and use of models and simulations (MS), while ensuring acceptance criteria are defined by the program project and approved by the responsible Technical Authority. It also provides an approved set of requirements, recommendations, and criteria with which MS may be developed, accepted, and used in support of NASA activities. As the MS disciplines employed and application areas involved are broad, the common aspects of MS across all NASA activities are addressed. The discipline-specific details of a given MS should be obtained from relevant recommended practices. The primary purpose is to reduce the risks associated with MS-influenced decisions by ensuring the complete communication of the credibility of MS results.

  17. Simulations of space charge neutralization in a magnetized electron cooler

    Energy Technology Data Exchange (ETDEWEB)

    Gerity, James [Texas A-M; McIntyre, Peter M. [Texas A-M; Bruhwiler, David Leslie [RadiaSoft, Boulder; Hall, Christopher [RadiaSoft, Boulder; Moens, Vince Jan [Ecole Polytechnique, Lausanne; Park, Chong Shik [Fermilab; Stancari, Giulio [Fermilab

    2017-02-02

    Magnetized electron cooling at relativistic energies and Ampere scale current is essential to achieve the proposed ion luminosities in a future electron-ion collider (EIC). Neutralization of the space charge in such a cooler can significantly increase the magnetized dynamic friction and, hence, the cooling rate. The Warp framework is being used to simulate magnetized electron beam dynamics during and after the build-up of neutralizing ions, via ionization of residual gas in the cooler. The design follows previous experiments at Fermilab as a verification case. We also discuss the relevance to EIC designs.

  18. Simulation of Electron Beam Trajectory of Thermionic Electron Gun Type with Pierce Electrode

    International Nuclear Information System (INIS)

    Suprapto; Djoko-SP; Djasiman

    2000-01-01

    The simulation of electron beam trajectory for electron gun of electron beam machine has been done. The simulation is carried out according to mechanical design of the electron gun. The simulation is carried out by using the software made by Andrzej Soltan Institute for Nuclear Studies, Swierk-Poland. The result obtained from simulation is approximately parallel electron beam trajectory of 20 mA beam current at 0.66 kV anode voltage, 15 mm cathode-anode distance and 67.5 o cathode angle. Arrangement of electron gun and accelerating tube with 15 kV voltage between anode and the first electrode of accelerating tube yields focus distance of 34 mm from the to cathode. To obtain the approximately parallel beam trajectory which has -0.03 o entrance angles to accelerating tube, the suitable cathode-anode voltage is 12.66 kV. With the entrance angle of -0.03 o it is expected that the electron beam can be accelerated and the beam profile has a small divergence after passing the accelerating tube. (author)

  19. A simulation framework for the CMS Track Trigger electronics

    CERN Document Server

    Amstutz, Christian; Weber, Marc; Palla, Fabrizio

    2014-01-01

    A simulation framework has been developed to test and characterize algorithms, architectures and hardware implementations of the vastly complex CMS Track Trigger for the high luminosity upgrade of the CMS experiment at the Large Hadron Collider in Geneva. High-level SystemC models of all system components have been developed to simulate a portion of the track trigger. The simulation of the system components together with input data from physics simulations allows evaluating figures of merit, like delays or bandwidths, under realistic conditions. The use of SystemC for high-level modelling allows \\mbox{co-simulation} with models developed in Hardware Description Languages, e.g.~VHDL or Verilog. Therefore, the simulation framework can also be used as a test bench for digital modules developed for the final system.

  20. A simulation framework for the CMS Track Trigger electronics

    International Nuclear Information System (INIS)

    Amstutz, C.; Weber, M.; Magazzù, G.; Palla, F.

    2015-01-01

    A simulation framework has been developed to test and characterize algorithms, architectures and hardware implementations of the vastly complex CMS Track Trigger for the high luminosity upgrade of the CMS experiment at the Large Hadron Collider in Geneva. High-level SystemC models of all system components have been developed to simulate a portion of the track trigger. The simulation of the system components together with input data from physics simulations allows evaluating figures of merit, like delays or bandwidths, under realistic conditions. The use of SystemC for high-level modelling allows co-simulation with models developed in Hardware Description Languages, e.g. VHDL or Verilog. Therefore, the simulation framework can also be used as a test bench for digital modules developed for the final system

  1. A simulation framework for the CMS Track Trigger electronics

    Science.gov (United States)

    Amstutz, C.; Magazzù, G.; Weber, M.; Palla, F.

    2015-03-01

    A simulation framework has been developed to test and characterize algorithms, architectures and hardware implementations of the vastly complex CMS Track Trigger for the high luminosity upgrade of the CMS experiment at the Large Hadron Collider in Geneva. High-level SystemC models of all system components have been developed to simulate a portion of the track trigger. The simulation of the system components together with input data from physics simulations allows evaluating figures of merit, like delays or bandwidths, under realistic conditions. The use of SystemC for high-level modelling allows co-simulation with models developed in Hardware Description Languages, e.g. VHDL or Verilog. Therefore, the simulation framework can also be used as a test bench for digital modules developed for the final system.

  2. MODELING SIMULATION AND PERFORMANCE STUDY OF GRIDCONNECTED PHOTOVOLTAIC ENERGY SYSTEM

    OpenAIRE

    Nagendra K; Karthik J; Keerthi Rao C; Kumar Raja Pemmadi

    2017-01-01

    This paper presents Modeling Simulation of grid connected Photovoltaic Energy System and performance study using MATLAB/Simulink. The Photovoltaic energy system is considered in three main parts PV Model, Power conditioning System and Grid interface. The Photovoltaic Model is inter-connected with grid through full scale power electronic devices. The simulation is conducted on the PV energy system at normal temperature and at constant load by using MATLAB.

  3. Electronic excitations and their effect on the interionic forces in simulations of radiation damage in metals

    International Nuclear Information System (INIS)

    Race, C P; Mason, D R; Sutton, A P

    2009-01-01

    Using time-dependent tight-binding simulations of radiation damage cascades in a model metal we directly investigate the nature of the excitations of a system of quantum mechanical electrons in response to the motion of a set of classical ions. We furthermore investigate the effect of these excitations on the attractive electronic forces between the ions. We find that the electronic excitations are well described by a Fermi-Dirac distribution at some elevated temperature, even in the absence of the direct electron-electron interactions that would be required in order to thermalize a non-equilibrium distribution. We explain this result in terms of the spectrum of characteristic frequencies of the ionic motion. Decomposing the electronic force into four well-defined components within the basis of instantaneous electronic eigenstates, we find that the effect of accumulated excitations in weakening the interionic bonds is mostly (95%) accounted for by a thermal model for the electronic excitations. This result justifies the use of the simplifying assumption of a thermalized electron system in simulations of radiation damage with an electronic temperature dependence and in the development of temperature-dependent classical potentials.

  4. Electronic excitations and their effect on the interionic forces in simulations of radiation damage in metals.

    Science.gov (United States)

    Race, C P; Mason, D R; Sutton, A P

    2009-03-18

    Using time-dependent tight-binding simulations of radiation damage cascades in a model metal we directly investigate the nature of the excitations of a system of quantum mechanical electrons in response to the motion of a set of classical ions. We furthermore investigate the effect of these excitations on the attractive electronic forces between the ions. We find that the electronic excitations are well described by a Fermi-Dirac distribution at some elevated temperature, even in the absence of the direct electron-electron interactions that would be required in order to thermalize a non-equilibrium distribution. We explain this result in terms of the spectrum of characteristic frequencies of the ionic motion. Decomposing the electronic force into four well-defined components within the basis of instantaneous electronic eigenstates, we find that the effect of accumulated excitations in weakening the interionic bonds is mostly (95%) accounted for by a thermal model for the electronic excitations. This result justifies the use of the simplifying assumption of a thermalized electron system in simulations of radiation damage with an electronic temperature dependence and in the development of temperature-dependent classical potentials.

  5. Simulation Models for Socioeconomic Inequalities in Health: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Niko Speybroeck

    2013-11-01

    Full Text Available Background: The emergence and evolution of socioeconomic inequalities in health involves multiple factors interacting with each other at different levels. Simulation models are suitable for studying such complex and dynamic systems and have the ability to test the impact of policy interventions in silico. Objective: To explore how simulation models were used in the field of socioeconomic inequalities in health. Methods: An electronic search of studies assessing socioeconomic inequalities in health using a simulation model was conducted. Characteristics of the simulation models were extracted and distinct simulation approaches were identified. As an illustration, a simple agent-based model of the emergence of socioeconomic differences in alcohol abuse was developed. Results: We found 61 studies published between 1989 and 2013. Ten different simulation approaches were identified. The agent-based model illustration showed that multilevel, reciprocal and indirect effects of social determinants on health can be modeled flexibly. Discussion and Conclusions: Based on the review, we discuss the utility of using simulation models for studying health inequalities, and refer to good modeling practices for developing such models. The review and the simulation model example suggest that the use of simulation models may enhance the understanding and debate about existing and new socioeconomic inequalities of health frameworks.

  6. Simulation Tools for Power Electronics Courses Based on Java Technologies

    Science.gov (United States)

    Canesin, Carlos A.; Goncalves, Flavio A. S.; Sampaio, Leonardo P.

    2010-01-01

    This paper presents interactive power electronics educational tools. These interactive tools make use of the benefits of Java language to provide a dynamic and interactive approach to simulating steady-state ideal rectifiers (uncontrolled and controlled; single-phase and three-phase). Additionally, this paper discusses the development and use of…

  7. Developments in the electron gun simulation program, EGUN

    International Nuclear Information System (INIS)

    Herrmannsfeldt, W.B.

    1994-11-01

    This paper discusses the developments in the electron gun simulation programs that are based on EGUN with its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications of this evolution on EGN2 are discussed. Some examples and a review of the capabilities of the EGUN family are described

  8. Developments in the electron gun simulation program, EGUN

    Science.gov (United States)

    Herrmannsfeldt, W. B.

    1995-07-01

    This paper discusses the developments in the electron gun simulation programs that are based on EGUN with its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications of this evolution on EGN2 are discussed. Some examples and a review of the capabilities of the EGUN family are described.

  9. Simulation of tail distributions in electron-positron circular colliders

    International Nuclear Information System (INIS)

    Irwin, J.

    1992-02-01

    In addition to the Gaussian shaped core region, particle bunches in electron-positron circular colliders have a rarefied halo region of importance in determining beam lifetimes and backgrounds in particle detectors. A method is described which allows simulation of halo particle distributions

  10. Three-dimensional simulations of free-electron laser physics

    International Nuclear Information System (INIS)

    McVey, B.D.

    1985-09-01

    A computer code has been developed to simulate three-dimensional free-electron laser physics. A mathematical formulation of the FEL equations is presented, and the numerical solution of the problem is described. Sample results from the computer code are discussed. 23 refs., 6 figs., 2 tabs

  11. Quantum simulations of small electron-hole complexes

    International Nuclear Information System (INIS)

    Lee, M.A.; Kalia, R.K.; Vashishta, P.D.

    1984-09-01

    The Green's Function Monte Carlo method is applied to the calculation of the binding energies of electron-hole complexes in semiconductors. The quantum simulation method allows the unambiguous determination of the ground state energy and the effects of band anisotropy on the binding energy. 22 refs., 1 fig

  12. Molecular electronics: insight from first-principles transport simulations.

    Science.gov (United States)

    Paulsson, Magnus; Frederiksen, Thomas; Brandbyge, Mads

    2010-01-01

    Conduction properties of nanoscale contacts can be studied using first-principles simulations. Such calculations give insight into details behind the conductance that is not readily available in experiments. For example, we may learn how the bonding conditions of a molecule to the electrodes affect the electronic transport. Here we describe key computational ingredients and discuss these in relation to simulations for scanning tunneling microscopy (STM) experiments with C60 molecules where the experimental geometry is well characterized. We then show how molecular dynamics simulations may be combined with transport calculations to study more irregular situations, such as the evolution of a nanoscale contact with the mechanically controllable break-junction technique. Finally we discuss calculations of inelastic electron tunnelling spectroscopy as a characterization technique that reveals information about the atomic arrangement and transport channels.

  13. Analytical local electron-electron interaction model potentials for atoms

    International Nuclear Information System (INIS)

    Neugebauer, Johannes; Reiher, Markus; Hinze, Juergen

    2002-01-01

    Analytical local potentials for modeling the electron-electron interaction in an atom reduce significantly the computational effort in electronic structure calculations. The development of such potentials has a long history, but some promising ideas have not yet been taken into account for further improvements. We determine a local electron-electron interaction potential akin to those suggested by Green et al. [Phys. Rev. 184, 1 (1969)], which are widely used in atom-ion scattering calculations, electron-capture processes, and electronic structure calculations. Generalized Yukawa-type model potentials are introduced. This leads, however, to shell-dependent local potentials, because the origin behavior of such potentials is different for different shells as has been explicated analytically [J. Neugebauer, M. Reiher, and J. Hinze, Phys. Rev. A 65, 032518 (2002)]. It is found that the parameters that characterize these local potentials can be interpolated and extrapolated reliably for different nuclear charges and different numbers of electrons. The analytical behavior of the corresponding localized Hartree-Fock potentials at the origin and at long distances is utilized in order to reduce the number of fit parameters. It turns out that the shell-dependent form of Green's potential, which we also derive, yields results of comparable accuracy using only one shell-dependent parameter

  14. Verifying and Validating Simulation Models

    Energy Technology Data Exchange (ETDEWEB)

    Hemez, Francois M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

    This presentation is a high-level discussion of the Verification and Validation (V&V) of computational models. Definitions of V&V are given to emphasize that “validation” is never performed in a vacuum; it accounts, instead, for the current state-of-knowledge in the discipline considered. In particular comparisons between physical measurements and numerical predictions should account for their respective sources of uncertainty. The differences between error (bias), aleatoric uncertainty (randomness) and epistemic uncertainty (ignorance, lack-of- knowledge) are briefly discussed. Four types of uncertainty in physics and engineering are discussed: 1) experimental variability, 2) variability and randomness, 3) numerical uncertainty and 4) model-form uncertainty. Statistical sampling methods are available to propagate, and analyze, variability and randomness. Numerical uncertainty originates from the truncation error introduced by the discretization of partial differential equations in time and space. Model-form uncertainty is introduced by assumptions often formulated to render a complex problem more tractable and amenable to modeling and simulation. The discussion concludes with high-level guidance to assess the “credibility” of numerical simulations, which stems from the level of rigor with which these various sources of uncertainty are assessed and quantified.

  15. Advances in Intelligent Modelling and Simulation Simulation Tools and Applications

    CERN Document Server

    Oplatková, Zuzana; Carvalho, Marco; Kisiel-Dorohinicki, Marek

    2012-01-01

    The human capacity to abstract complex systems and phenomena into simplified models has played a critical role in the rapid evolution of our modern industrial processes and scientific research. As a science and an art, Modelling and Simulation have been one of the core enablers of this remarkable human trace, and have become a topic of great importance for researchers and practitioners. This book was created to compile some of the most recent concepts, advances, challenges and ideas associated with Intelligent Modelling and Simulation frameworks, tools and applications. The first chapter discusses the important aspects of a human interaction and the correct interpretation of results during simulations. The second chapter gets to the heart of the analysis of entrepreneurship by means of agent-based modelling and simulations. The following three chapters bring together the central theme of simulation frameworks, first describing an agent-based simulation framework, then a simulator for electrical machines, and...

  16. Numerically robust and efficient nonlocal electron transport in 2D DRACO simulations

    Science.gov (United States)

    Cao, Duc; Chenhall, Jeff; Moses, Greg; Delettrez, Jacques; Collins, Tim

    2013-10-01

    An improved implicit algorithm based on Schurtz, Nicolai and Busquet (SNB) algorithm for nonlocal electron transport is presented. Validation with direct drive shock timing experiments and verification with the Goncharov nonlocal model in 1D LILAC simulations demonstrate the viability of this efficient algorithm for producing 2D lagrangian radiation hydrodynamics direct drive simulations. Additionally, simulations provide strong incentive to further modify key parameters within the SNB theory, namely the ``mean free path.'' An example 2D polar drive simulation to study 2D effects of the nonlocal flux as well as mean free path modifications will also be presented. This research was supported by the University of Rochester Laboratory for Laser Energetics.

  17. Monte Carlo simulation of positron induced secondary electrons in thin carbon foils

    International Nuclear Information System (INIS)

    Cai, L H; Yang, B; Ling, C C; Beling, C D; Fung, S

    2011-01-01

    Emission of secondary electrons induced by the passage of low energy positrons through thin carbon foils was studied by the Monte Carlo method. The positron and electron elastic cross sections were calculated by partial wave analysis. The inelastic positron-valence-electron was described by the energy loss function obtained from dielectric theory. The positron-core-electron interaction was modelled by the Gryzinski's excitation function. Positron transport inside the carbon foil was simulated in detail. Secondary electrons created by positrons and high energy secondary electrons through inelastic interactions were tracked through the foil. The positron transmission coefficient and secondary electron yielded in forward and backward geometry are calculated and dependences on positron energy and carbon foil thickness are discussed.

  18. Short-duration Electron Precipitation Studied by Test Particle Simulation

    Directory of Open Access Journals (Sweden)

    Jaejin Lee

    2015-12-01

    Full Text Available Energy spectra of electron microbursts from 170 keV to 340 keV have been measured by the solid-state detectors aboard the low-altitude (680 km polar-orbiting Korean STSAT-1 (Science and Technology SATellite. These measurements have revealed two important characteristics unique to the microbursts: (1 They are produced by a fast-loss cone-filling process in which the interaction time for pitch-angle scattering is less than 50 ms and (2 The e-folding energy of the perpendicular component is larger than that of the parallel component, and the loss cone is not completely filled by electrons. To understand how wave-particle interactions could generate microbursts, we performed a test particle simulation and investigated how the waves scattered electron pitch angles within the timescale required for microburst precipitation. The application of rising-frequency whistler-mode waves to electrons of different energies moving in a dipole magnetic field showed that chorus magnetic wave fields, rather than electric fields, were the main cause of microburst events, which implied that microbursts could be produced by a quasi-adiabatic process. In addition, the simulation results showed that high-energy electrons could resonate with chorus waves at high magnetic latitudes where the loss cone was larger, which might explain the decreased e-folding energy of precipitated microbursts compared to that of trapped electrons.

  19. Theory and Simulation of an Inverse Free Electron Laser Experiment

    Science.gov (United States)

    Guo, S. K.; Bhattacharjee, A.; Fang, J. M.; Marshall, T. C.

    1996-11-01

    An experimental demonstration of the acceleration of electrons using a high power CO2 laser in an inverse free electron laser (IFEL) is underway at the Brookhaven National Laboratory. This experiment has generated data, which we are attempting to simulate. Included in our studies are such effects as: a low-loss metallic waveguide with a dielectric coating on the walls; multi-mode coupling due to self-consistent interaction between the electrons and the optical wave; space charge (which is significant at lower laser power); energy-spread of the electrons; arbitrary wiggler field profile; and slippage. Two types of wiggler profile have been considered: a linear taper of the period, and a step-taper of the period (the period is ~ 3cm, the field is ~ 1T, and the wiggler length is 47cm). The energy increment of the electrons ( ~ 1-2%) is analyzed in detail as a function of laser power, wiggler parameters, and the initial beam energy (40MeV). For laser power ~ 0.5GW, the predictions of the simulations are in good accord with experimental results. A matter currently under study is the discrepancy between theory and observations for the electron energy distribution observed at the end of the IFEL. This work is supported by the Department of Energy.

  20. MODELLING, SIMULATING AND OPTIMIZING BOILERS

    DEFF Research Database (Denmark)

    Sørensen, Kim; Condra, Thomas Joseph; Houbak, Niels

    2004-01-01

    In the present work a framework for optimizing the design of boilers for dynamic operation has been developed. A cost function to be minimized during the optimization has been formulated and for the present design variables related to the Boiler Volume and the Boiler load Gradient (i.e. ring rate...... on the boiler) have been dened. Furthermore a number of constraints related to: minimum and maximum boiler load gradient, minimum boiler size, Shrinking and Swelling and Steam Space Load have been dened. For dening the constraints related to the required boiler volume a dynamic model for simulating the boiler...... performance has been developed. Outputs from the simulations are shrinking and swelling of water level in the drum during for example a start-up of the boiler, these gures combined with the requirements with respect to allowable water level uctuations in the drum denes the requirements with respect to drum...

  1. Radiation Modeling with Direct Simulation Monte Carlo

    Science.gov (United States)

    Carlson, Ann B.; Hassan, H. A.

    1991-01-01

    Improvements in the modeling of radiation in low density shock waves with direct simulation Monte Carlo (DSMC) are the subject of this study. A new scheme to determine the relaxation collision numbers for excitation of electronic states is proposed. This scheme attempts to move the DSMC programs toward a more detailed modeling of the physics and more reliance on available rate data. The new method is compared with the current modeling technique and both techniques are compared with available experimental data. The differences in the results are evaluated. The test case is based on experimental measurements from the AVCO-Everett Research Laboratory electric arc-driven shock tube of a normal shock wave in air at 10 km/s and .1 Torr. The new method agrees with the available data as well as the results from the earlier scheme and is more easily extrapolated to di erent ow conditions.

  2. SEMI Modeling and Simulation Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Hermina, W.L.

    2000-10-02

    With the exponential growth in the power of computing hardware and software, modeling and simulation is becoming a key enabler for the rapid design of reliable Microsystems. One vision of the future microsystem design process would include the following primary software capabilities: (1) The development of 3D part design, through standard CAD packages, with automatic design rule checks that guarantee the manufacturability and performance of the microsystem. (2) Automatic mesh generation, for 3D parts as manufactured, that permits computational simulation of the process steps, and the performance and reliability analysis for the final microsystem. (3) Computer generated 2D layouts for process steps that utilize detailed process models to generate the layout and process parameter recipe required to achieve the desired 3D part. (4) Science-based computational tools that can simulate the process physics, and the coupled thermal, fluid, structural, solid mechanics, electromagnetic and material response governing the performance and reliability of the microsystem. (5) Visualization software that permits the rapid visualization of 3D parts including cross-sectional maps, performance and reliability analysis results, and process simulation results. In addition to these desired software capabilities, a desired computing infrastructure would include massively parallel computers that enable rapid high-fidelity analysis, coupled with networked compute servers that permit computing at a distance. We now discuss the individual computational components that are required to achieve this vision. There are three primary areas of focus: design capabilities, science-based capabilities and computing infrastructure. Within each of these areas, there are several key capability requirements.

  3. Photovoltaic array performance simulation models

    Energy Technology Data Exchange (ETDEWEB)

    Menicucci, D. F.

    1986-09-15

    The experience of the solar industry confirms that, despite recent cost reductions, the profitability of photovoltaic (PV) systems is often marginal and the configuration and sizing of a system is a critical problem for the design engineer. Construction and evaluation of experimental systems are expensive and seldom justifiable. A mathematical model or computer-simulation program is a desirable alternative, provided reliable results can be obtained. Sandia National Laboratories, Albuquerque (SNLA), has been studying PV-system modeling techniques in an effort to develop an effective tool to be used by engineers and architects in the design of cost-effective PV systems. This paper reviews two of the sources of error found in previous PV modeling programs, presents the remedies developed to correct these errors, and describes a new program that incorporates these improvements.

  4. Modeling ion sensing in molecular electronics

    International Nuclear Information System (INIS)

    Chen, Caroline J.; Smeu, Manuel; Ratner, Mark A.

    2014-01-01

    We examine the ability of molecules to sense ions by measuring the change in molecular conductance in the presence of such charged species. The detection of protons (H + ), alkali metal cations (M + ), calcium ions (Ca 2+ ), and hydronium ions (H 3 O + ) is considered. Density functional theory (DFT) is used within the Keldysh non-equilibrium Green's function framework (NEGF) to model electron transport properties of quinolinedithiol (QDT, C 9 H 7 NS 2 ), bridging Al electrodes. The geometry of the transport region is relaxed with DFT. The transport properties of the device are modeled with NEGF-DFT to determine if this device can distinguish among the M + + QDT species containing monovalent cations, where M + = H + , Li + , Na + , or K + . Because of the asymmetry of QDT in between the two electrodes, both positive and negative biases are considered. The electron transmission function and conductance properties are simulated for electrode biases in the range from −0.5 V to 0.5 V at increments of 0.1 V. Scattering state analysis is used to determine the molecular orbitals that are the main contributors to the peaks in the transmission function near the Fermi level of the electrodes, and current-voltage relationships are obtained. The results show that QDT can be used as a proton detector by measuring transport through it and can conceivably act as a pH sensor in solutions. In addition, QDT may be able to distinguish among different monovalent species. This work suggests an approach to design modern molecular electronic conductance sensors with high sensitivity and specificity using well-established quantum chemistry

  5. Numerical Simulations of X-Ray Free Electron Lasers (XFEL)

    KAUST Repository

    Antonelli, Paolo; Athanassoulis, Agissilaos; Huang, Zhongyi; Markowich, Peter A.

    2014-01-01

    and approximations has attracted increased attention. In this model the electrons move under a rapidly oscillating electromagnetic field, and the convergence of the problem to an effective time-averaged one is examined. We use an operator splitting pseudospectral

  6. Simulated annealing model of acupuncture

    Science.gov (United States)

    Shang, Charles; Szu, Harold

    2015-05-01

    The growth control singularity model suggests that acupuncture points (acupoints) originate from organizers in embryogenesis. Organizers are singular points in growth control. Acupuncture can cause perturbation of a system with effects similar to simulated annealing. In clinical trial, the goal of a treatment is to relieve certain disorder which corresponds to reaching certain local optimum in simulated annealing. The self-organizing effect of the system is limited and related to the person's general health and age. Perturbation at acupoints can lead a stronger local excitation (analogous to higher annealing temperature) compared to perturbation at non-singular points (placebo control points). Such difference diminishes as the number of perturbed points increases due to the wider distribution of the limited self-organizing activity. This model explains the following facts from systematic reviews of acupuncture trials: 1. Properly chosen single acupoint treatment for certain disorder can lead to highly repeatable efficacy above placebo 2. When multiple acupoints are used, the result can be highly repeatable if the patients are relatively healthy and young but are usually mixed if the patients are old, frail and have multiple disorders at the same time as the number of local optima or comorbidities increases. 3. As number of acupoints used increases, the efficacy difference between sham and real acupuncture often diminishes. It predicted that the efficacy of acupuncture is negatively correlated to the disease chronicity, severity and patient's age. This is the first biological - physical model of acupuncture which can predict and guide clinical acupuncture research.

  7. Measurements and simulations of seeded electron microbunches with collective effects

    Directory of Open Access Journals (Sweden)

    K. Hacker

    2015-09-01

    Full Text Available Measurements of the longitudinal phase-space distributions of electron bunches seeded with an external laser were done in order to study the impact of collective effects on seeded microbunches in free-electron lasers. When the collective effects of Coulomb forces in a drift space and coherent synchrotron radiation in a chicane are considered, velocity bunching of a seeded microbunch appears to be a viable alternative to compression with a magnetic chicane under high-gain harmonic generation seeding conditions. Measurements of these effects on seeded electron microbunches were performed with a rf deflecting structure and a dipole magnet which streak out the electron bunch for single-shot images of the longitudinal phase-space distribution. Particle tracking simulations in 3D predicted the compression dynamics of the seeded microbunches with collective effects.

  8. Design, simulation and construction of quadrupole magnets for focusing electron beam in powerful industrial electron accelerator

    Directory of Open Access Journals (Sweden)

    S KH Mousavi

    2015-09-01

    Full Text Available In this paper the design and simulation of quadrupole magnets and electron beam optical of that by CST Studio code has been studied. Based on simulation result the magnetic quadrupole has been done for using in beam line of first Iranian powerful electron accelerator. For making the suitable magnetic field the effects of material and core geometry and coils current variation on quadrupole magnetic field have been studied. For test of quadrupole magnet the 10 MeV beam energy and 0.5 pi mm mrad emittance of input beam has been considered. We see the electron beam through the quadrupole magnet focus in one side and defocus in other side. The optimum of distance between two quadrupole magnets for low emittance have been achieved. The simulation results have good agreement with experimental results

  9. Numerical simulation of RCS for carrier electronic warfare airplanes

    OpenAIRE

    Yue Kuizhi; Liu Wenlin; Li Guanxiong; Ji Jinzu; Yu Dazhao

    2015-01-01

    This paper studies the radar cross section (RCS) of carrier electronic warfare airplanes. Under the typical naval operations section, the mathematical model of the radar wave’s pitch angle incidence range analysis is established. Based on the CATIA software, considering dynamic deflections of duck wing leading edge flaps, flaperons, horizontal tail, and rudder, as well as aircraft with air-to-air missile, anti-radiation missile, electronic jamming pod, and other weapons, the 3D models of carr...

  10. Operations planning simulation: Model study

    Science.gov (United States)

    1974-01-01

    The use of simulation modeling for the identification of system sensitivities to internal and external forces and variables is discussed. The technique provides a means of exploring alternate system procedures and processes, so that these alternatives may be considered on a mutually comparative basis permitting the selection of a mode or modes of operation which have potential advantages to the system user and the operator. These advantages are measurements is system efficiency are: (1) the ability to meet specific schedules for operations, mission or mission readiness requirements or performance standards and (2) to accomplish the objectives within cost effective limits.

  11. PIC simulation of electron acceleration in an underdense plasma

    Directory of Open Access Journals (Sweden)

    S Darvish Molla

    2011-06-01

    Full Text Available One of the interesting Laser-Plasma phenomena, when the laser power is high and ultra intense, is the generation of large amplitude plasma waves (Wakefield and electron acceleration. An intense electromagnetic laser pulse can create plasma oscillations through the action of the nonlinear pondermotive force. electrons trapped in the wake can be accelerated to high energies, more than 1 TW. Of the wide variety of methods for generating a regular electric field in plasmas with strong laser radiation, the most attractive one at the present time is the scheme of the Laser Wake Field Accelerator (LWFA. In this method, a strong Langmuir wave is excited in the plasma. In such a wave, electrons are trapped and can acquire relativistic energies, accelerated to high energies. In this paper the PIC simulation of wakefield generation and electron acceleration in an underdense plasma with a short ultra intense laser pulse is discussed. 2D electromagnetic PIC code is written by FORTRAN 90, are developed, and the propagation of different electromagnetic waves in vacuum and plasma is shown. Next, the accuracy of implementation of 2D electromagnetic code is verified, making it relativistic and simulating the generating of wakefield and electron acceleration in an underdense plasma. It is shown that when a symmetric electromagnetic pulse passes through the plasma, the longitudinal field generated in plasma, at the back of the pulse, is weaker than the one due to an asymmetric electromagnetic pulse, and thus the electrons acquire less energy. About the asymmetric pulse, when front part of the pulse has smaller time rise than the back part of the pulse, a stronger wakefield generates, in plasma, at the back of the pulse, and consequently the electrons acquire more energy. In an inverse case, when the rise time of the back part of the pulse is bigger in comparison with that of the back part, a weaker wakefield generates and this leads to the fact that the electrons

  12. Simulation of off-energy electron background in DELPHI

    CERN Document Server

    Falk, E; Von Holtey, Georg

    1997-01-01

    Monte Carlo simulations of off-energy electron background in the DELPHI luminometer STIC are reported. The study simulates the running conditions at 68 GeV with and without bunch trains. The electrostatic separators, which create the vertical separation bumps for the the bunch trains, cause a high concentration of background in the vertical plane. The simulations are compared to LEP data taken under similar running conditions. A comparison between the simulated running conditions at 68 GeV and those of the new LEP2 beam optics at 80.5 GeV is made. Moreover, the study investigates background components entering STIC elsewhere that through the front of the detector, and a significant portion is found to enter either from the back or from below. Possible improvements of the background situation are also discussed.

  13. Simulation of electron displacement damage in a high voltage electron microscope

    International Nuclear Information System (INIS)

    Ono, Susumu; Kanaya, Koichi

    1979-01-01

    By applying the fundamental theory of the neutron cooling to the conservation law of energy and momentum, the threshold energies of incident electrons for displacing atoms are calculated and illustrated periodically for the atomic number. And the observable damage due to the secondary action of displaced atoms in the practical use of a high voltage electron microscope is described for several materials and accelerating voltages. The trajectories of incident electrons and displaced atoms in several materials are simulated by a Monte-Carlo method, using rigorous formulas of electron scattering events, i.e. elastic and inelastic scattering cross-sections, ionization loss and plasmon excitation. The simulation results are substantially agreement with experiments. (author)

  14. Trapped Electron Instability of Electron Plasma Waves: Vlasov simulations and theory

    Science.gov (United States)

    Berger, Richard; Chapman, Thomas; Brunner, Stephan

    2013-10-01

    The growth of sidebands of a large-amplitude electron plasma wave is studied with Vlasov simulations for a range of amplitudes (. 001 vph = +/-ωbe , where vph =ω0 /k0 and ωbe is the bounce frequency of a deeply trapped electron. In 2D simulations, we find that the instability persists and co-exists with the filamentation instability. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD.

  15. Computer simulation of electronic excitation in atomic collision cascades

    International Nuclear Information System (INIS)

    Duvenbeck, A.

    2007-01-01

    The impact of an keV atomic particle onto a solid surface initiates a complex sequence of collisions among target atoms in a near-surface region. The temporal and spatial evolution of this atomic collision cascade leads to the emission of particles from the surface - a process usually called sputtering. In modern surface analysis the so called SIMS technology uses the flux of sputtered particles as a source of information on the microscopical stoichiometric structure in the proximity of the bombarded surface spots. By laterally varying the bombarding spot on the surface, the entire target can be scanned and chemically analyzed. However, the particle detection, which bases upon deflection in electric fields, is limited to those species that leave the surface in an ionized state. Due to the fact that the ionized fraction of the total flux of sputtered atoms often only amounts to a few percent or even less, the detection is often hampered by rather low signals. Moreover, it is well known, that the ionization probability of emitted particles does not only depend on the elementary species, but also on the local environment from which a particle leaves the surface. Therefore, the measured signals for different sputtered species do not necessarily represent the stoichiometric composition of the sample. In the literature, this phenomenon is known as the Matrix Effect in SIMS. In order to circumvent this principal shortcoming of SIMS, the present thesis develops an alternative computer simulation concept, which treats the electronic energy losses of all moving atoms as excitation sources feeding energy into the electronic sub-system of the solid. The particle kinetics determining the excitation sources are delivered by classical molecular dynamics. The excitation energy calculations are combined with a diffusive transport model to describe the spread of excitation energy from the initial point of generation. Calculation results yield a space- and time-resolved excitation

  16. Computer simulation of electronic excitation in atomic collision cascades

    Energy Technology Data Exchange (ETDEWEB)

    Duvenbeck, A.

    2007-04-05

    The impact of an keV atomic particle onto a solid surface initiates a complex sequence of collisions among target atoms in a near-surface region. The temporal and spatial evolution of this atomic collision cascade leads to the emission of particles from the surface - a process usually called sputtering. In modern surface analysis the so called SIMS technology uses the flux of sputtered particles as a source of information on the microscopical stoichiometric structure in the proximity of the bombarded surface spots. By laterally varying the bombarding spot on the surface, the entire target can be scanned and chemically analyzed. However, the particle detection, which bases upon deflection in electric fields, is limited to those species that leave the surface in an ionized state. Due to the fact that the ionized fraction of the total flux of sputtered atoms often only amounts to a few percent or even less, the detection is often hampered by rather low signals. Moreover, it is well known, that the ionization probability of emitted particles does not only depend on the elementary species, but also on the local environment from which a particle leaves the surface. Therefore, the measured signals for different sputtered species do not necessarily represent the stoichiometric composition of the sample. In the literature, this phenomenon is known as the Matrix Effect in SIMS. In order to circumvent this principal shortcoming of SIMS, the present thesis develops an alternative computer simulation concept, which treats the electronic energy losses of all moving atoms as excitation sources feeding energy into the electronic sub-system of the solid. The particle kinetics determining the excitation sources are delivered by classical molecular dynamics. The excitation energy calculations are combined with a diffusive transport model to describe the spread of excitation energy from the initial point of generation. Calculation results yield a space- and time-resolved excitation

  17. Plykin type attractor in electronic device simulated in MULTISIM

    Science.gov (United States)

    Kuznetsov, Sergey P.

    2011-12-01

    An electronic device is suggested representing a non-autonomous dynamical system with hyperbolic chaotic attractor of Plykin type in the stroboscopic map, and the results of its simulation with software package NI MULTISIM are considered in comparison with numerical integration of the underlying differential equations. A main practical advantage of electronic devices of this kind is their structural stability that means insensitivity of the chaotic dynamics in respect to variations of functions and parameters of elements constituting the system as well as to interferences and noises.

  18. Electron-acoustic Instability Simulated By Modified Zakharov Equations

    Science.gov (United States)

    Jásenský, V.; Fiala, V.; Vána, O.; Trávnícek, P.; Hellinger, P.

    We present non-linear equations describing processes in plasma when electron - acoustic waves are excited. These waves are present for instance in the vicinity of Earth's bow shock and in the polar ionosphere. Frequently they are excited by an elec- tron beam in a plasma with two electron populations, a cold and hot one. We derive modified Zakharov equations from kinetic theory for such a case together with numer- ical method for solving of this type of equations. Bispectral analysis is used to show which non-linear wave processes are of importance in course of the instability. Finally, we compare these results with similar simulations using Vlasov approach.

  19. Aerodynamic Simulation Analysis of Unmanned Airborne Electronic Bomb

    Science.gov (United States)

    Yang, Jiaoying; Guo, Yachao

    2017-10-01

    For microelectronic bombs for UAVs, on the basis of the use of rotors to lift the insurance on the basis of ammunition, increased tail to increase stability. The aerodynamic simulation of the outer structure of the ammunition was carried out by FLUENT software. The resistance coefficient, the lift coefficient and the pitch moment coefficient under different angle of attack and Mach number were obtained, and the aerodynamic characteristics of the electronic bomb were studied. The pressure line diagram and the velocity line diagram of the flow around the bomb are further analyzed, and the rationality of the external structure is verified, which provides a reference for the subsequent design of the electronic bomb.

  20. Impulse pumping modelling and simulation

    International Nuclear Information System (INIS)

    Pierre, B; Gudmundsson, J S

    2010-01-01

    Impulse pumping is a new pumping method based on propagation of pressure waves. Of particular interest is the application of impulse pumping to artificial lift situations, where fluid is transported from wellbore to wellhead using pressure waves generated at wellhead. The motor driven element of an impulse pumping apparatus is therefore located at wellhead and can be separated from the flowline. Thus operation and maintenance of an impulse pump are facilitated. The paper describes the different elements of an impulse pumping apparatus, reviews the physical principles and details the modelling of the novel pumping method. Results from numerical simulations of propagation of pressure waves in water-filled pipelines are then presented for illustrating impulse pumping physical principles, and validating the described modelling with experimental data.

  1. A classical model for the electron

    International Nuclear Information System (INIS)

    Visser, M.

    1989-01-01

    The construction of classical and semi-classical models for the electron has had a long and distinguished history. Such models are useful more for what they teach us about field theory than what they teach us about the electron. In this Letter I exhibit a classical model of the electron consisting of ordinary electromagnetism coupled with a self-interacting version of Newtonian gravity. The gravitational binding energy of the system balances the electrostatic energy in such a manner that the total rest mass of the electron is finite. (orig.)

  2. Simulation model of a PWR power plant

    International Nuclear Information System (INIS)

    Larsen, N.

    1987-03-01

    A simulation model of a hypothetical PWR power plant is described. A large number of disturbances and failures in plant function can be simulated. The model is written as seven modules to the modular simulation system for continuous processes DYSIM and serves also as a user example of this system. The model runs in Fortran 77 on the IBM-PC-AT. (author)

  3. Xyce™ Parallel Electronic Simulator Reference Guide, Version 6.5

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Aadithya, Karthik V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Schiek, Richard L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Verley, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation

    2016-06-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users’ Guide. The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce. This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users’ Guide. The information herein is subject to change without notice. Copyright © 2002-2016 Sandia Corporation. All rights reserved.

  4. Development of models simulating operation of elements of radio devices, for solving problems of ensuring electromagnetic compatibility of radio electronic means

    Science.gov (United States)

    Glotov, V. V.; Ostroumov, I. V.; Romashchenko, M. A.

    2018-05-01

    To study the effect of phase-shift signals parameters on EMC of REM, a generalized signal generation model in a radio transmitter was developed which allows obtaining digital representations of phase-shift signals, which are a continuous pulse in the time domain and on the frequency axis with different signal element envelope shapes.

  5. Molecular models and simulations of layered materials

    International Nuclear Information System (INIS)

    Kalinichev, Andrey G.; Cygan, Randall Timothy; Heinz, Hendrik; Greathouse, Jeffery A.

    2008-01-01

    The micro- to nano-sized nature of layered materials, particularly characteristic of naturally occurring clay minerals, limits our ability to fully interrogate their atomic dispositions and crystal structures. The low symmetry, multicomponent compositions, defects, and disorder phenomena of clays and related phases necessitate the use of molecular models and modern simulation methods. Computational chemistry tools based on classical force fields and quantum-chemical methods of electronic structure calculations provide a practical approach to evaluate structure and dynamics of the materials on an atomic scale. Combined with classical energy minimization, molecular dynamics, and Monte Carlo techniques, quantum methods provide accurate models of layered materials such as clay minerals, layered double hydroxides, and clay-polymer nanocomposites

  6. Simulations of interference effects in gated two-dimensional ballistic electron systems

    DEFF Research Database (Denmark)

    Jauho, Antti-Pekka; Pichugin, K.N.; Sadreev, A.F.

    1999-01-01

    We present detailed simulations addressing recent electronic interference experiments,where a metallic gate is used to locally modify the Fermi wavelength of the charge carriers. Our numerical calculations are based on a solution of the one-particle Schrodinger equation for a realistic model of t...

  7. Coupled ion temperature gradient and trapped electron mode to electron temperature gradient mode gyrokinetic simulations

    International Nuclear Information System (INIS)

    Waltz, R. E.; Candy, J.; Fahey, M.

    2007-01-01

    Electron temperature gradient (ETG) transport is conventionally defined as the electron energy transport at high wave number (high-k) where ions are adiabatic and there can be no ion energy or plasma transport. Previous gyrokinetic simulations have assumed adiabatic ions (ETG-ai) and work on the small electron gyroradius scale. However such ETG-ai simulations with trapped electrons often do not have well behaved nonlinear saturation unless fully kinetic ions (ki) and proper ion scale zonal flow modes are included. Electron energy transport is separated into ETG-ki at high-k and ion temperature gradient-trapped electron mode (ITG/TEM) at low-k. Expensive (more computer-intensive), high-resolution, large-ion-scale flux-tube simulations coupling ITG/TEM and ETG-ki turbulence are presented. These require a high effective Reynolds number R≡[k(max)/k(min)] 2 =μ 2 , where μ=[ρ si /ρ si ] is the ratio of ion to electron gyroradii. Compute times scale faster than μ 3 . By comparing the coupled expensive simulations with (1) much cheaper (less compute-intensive), uncoupled, high-resolution, small, flux-tube ETG-ki and with (2) uncoupled low-resolution, large, flux-tube ITG/TEM simulations, and also by artificially turning ''off'' the low-k or high-k drives, it appears that ITG/TEM and ETG-ki transport are not strongly coupled so long as ETG-ki can access some nonadiabatic ion scale zonal flows and both high-k and low-k are linearly unstable. However expensive coupled simulations are required for physically accurate k-spectra of the transport and turbulence. Simulations with μ≥30 appear to represent the physical range μ>40. ETG-ki transport measured in ion gyro-Bohm units is weakly dependent on μ. For the mid-radius core tokamak plasma parameters studied, ETG-ki is about 10% of the electron energy transport, which in turn is about 30% of the total energy transport (with negligible ExB shear). However at large ExB shear sufficient to quench the low-k ITG

  8. Note: Simulation and test of a strip source electron gun.

    Science.gov (United States)

    Iqbal, Munawar; Islam, G U; Misbah, I; Iqbal, O; Zhou, Z

    2014-06-01

    We present simulation and test of an indirectly heated strip source electron beam gun assembly using Stanford Linear Accelerator Center (SLAC) electron beam trajectory program. The beam is now sharply focused with 3.04 mm diameter in the post anode region at 15.9 mm. The measured emission current and emission density were 1.12 A and 1.15 A/cm(2), respectively, that corresponds to power density of 11.5 kW/cm(2), at 10 kV acceleration potential. The simulated results were compared with then and now experiments and found in agreement. The gun is without any biasing, electrostatic and magnetic fields; hence simple and inexpensive. Moreover, it is now more powerful and is useful for accelerators technology due to high emission and low emittance parameters.

  9. METHES: A Monte Carlo collision code for the simulation of electron transport in low temperature plasmas

    Science.gov (United States)

    Rabie, M.; Franck, C. M.

    2016-06-01

    We present a freely available MATLAB code for the simulation of electron transport in arbitrary gas mixtures in the presence of uniform electric fields. For steady-state electron transport, the program provides the transport coefficients, reaction rates and the electron energy distribution function. The program uses established Monte Carlo techniques and is compatible with the electron scattering cross section files from the open-access Plasma Data Exchange Project LXCat. The code is written in object-oriented design, allowing the tracing and visualization of the spatiotemporal evolution of electron swarms and the temporal development of the mean energy and the electron number due to attachment and/or ionization processes. We benchmark our code with well-known model gases as well as the real gases argon, N2, O2, CF4, SF6 and mixtures of N2 and O2.

  10. Simulation of solution phase electron transfer in a compact donor-acceptor dyad.

    Science.gov (United States)

    Kowalczyk, Tim; Wang, Lee-Ping; Van Voorhis, Troy

    2011-10-27

    Charge separation (CS) and charge recombination (CR) rates in photosynthetic architectures are difficult to control, yet their ratio can make or break photon-to-current conversion efficiencies. A rational design approach to the enhancement of CS over CR requires a mechanistic understanding of the underlying electron-transfer (ET) process, including the role of the environment. Toward this goal, we introduce a QM/MM protocol for ET simulations and use it to characterize CR in the formanilide-anthraquinone dyad (FAAQ). Our simulations predict fast recombination of the charge-transfer excited state, in agreement with recent experiments. The computed electronic couplings show an electronic state dependence and are weaker in solution than in the gas phase. We explore the role of cis-trans isomerization on the CR kinetics, and we find strong correlation between the vertical energy gaps of the full simulations and a collective solvent polarization coordinate. Our approach relies on constrained density functional theory to obtain accurate diabatic electronic states on the fly for molecular dynamics simulations, while orientational and electronic polarization of the solvent is captured by a polarizable force field based on a Drude oscillator model. The method offers a unified approach to the characterization of driving forces, reorganization energies, electronic couplings, and nonlinear solvent effects in light-harvesting systems.

  11. Developments in the electron gun simulation program, EGUN

    International Nuclear Information System (INIS)

    Herrmannsfeldt, W.B.

    1995-01-01

    This paper discusses the developments in the electron gun simulation programs that are based on EGUN with its derivatives and supporting programs. Much of the code development has been inspired by technology changes in computer hardware; the implications of this evolution on EGN2 are discussed. Some examples and a review of the capabilities of the EGUN family are described. copyright 1995 American Institute of Physics

  12. Simulation and analysis of TE wave propagation for measurement of electron cloud densities in particle accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Sonnad, Kiran G., E-mail: kgs52@cornell.edu [CLASSE, Cornell University, Ithaca, NY (United States); Hammond, Kenneth C. [Department of Physics, Harvard University, Cambridge, MA (United States); Schwartz, Robert M. [CLASSE, Cornell University, Ithaca, NY (United States); Veitzer, Seth A. [Tech-X Corporation, Boulder, CO (United States)

    2014-08-01

    The use of transverse electric (TE) waves has proved to be a powerful, noninvasive method for estimating the densities of electron clouds formed in particle accelerators. Results from the plasma simulation program VSim have served as a useful guide for experimental studies related to this method, which have been performed at various accelerator facilities. This paper provides results of the simulation and modeling work done in conjunction with experimental efforts carried out at the Cornell electron storage ring “Test Accelerator” (CESRTA). This paper begins with a discussion of the phase shift induced by electron clouds in the transmission of RF waves, followed by the effect of reflections along the beam pipe, simulation of the resonant standing wave frequency shifts and finally the effects of external magnetic fields, namely dipoles and wigglers. A derivation of the dispersion relationship of wave propagation for arbitrary geometries in field free regions with a cold, uniform cloud density is also provided.

  13. Gyrokinetic Electron and Fully Kinetic Ion Particle Simulation of Collisionless Plasma Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yu Lin; Xueyi Wang; Liu Chen; Zhihong Lin

    2009-08-11

    Fully kinetic-particle simulations and hybrid simulations have been utilized for decades to investigate various fundamental plasma processes, such as magnetic reconnection, fast compressional waves, and wave-particle interaction. Nevertheless, due to disparate temporal and spatial scales between electrons and ions, existing fully kinetic-particle codes have to employ either unrealistically high electron-to-ion mass ratio, me/mi, or simulation domain limited to a few or a few ten's of the ion Larmor radii, or/and time much less than the global Alfven time scale in order to accommodate available computing resources. On the other hand, in the hybrid simulation, the ions are treated as fully kinetic particles but the electrons are treated as a massless fluid. The electron kinetic effects, e.g., wave-particle resonances and finite electron Larmor radius effects, are completely missing. Important physics, such as the electron transit time damping of fast compressional waves or the triggering mechanism of magnetic reconnection in collisionless plasmas is absent in the hybrid codes. Motivated by these considerations and noting that dynamics of interest to us has frequencies lower than the electron gyrofrequency, we planned to develop an innovative particle simulation model, gyrokinetic (GK) electrons and fully kinetic (FK) ions. In the GK-electron and FK-ion (GKe/FKi) particle simulation model, the rapid electron cyclotron motion is removed, while keeping finite electron Larmor radii, realistic me/mi ratio, wave-particle interactions, and off-diagonal components of electron pressure tensor. The computation power can thus be significantly improved over that of the full-particle codes. As planned in the project DE-FG02-05ER54826, we have finished the development of the new GK-electron and FK-ion scheme, finished its benchmark for a uniform plasma in 1-D, 2-D, and 3-D systems against linear waves obtained from analytical theories, and carried out a further convergence

  14. Gyrokinetic Electron and Fully Kinetic Ion Particle Simulation of Collisionless Plasma Dynamics

    International Nuclear Information System (INIS)

    Lin, Yu; Wang, Xueyi; Chen, Liu; Lin, Zhihong

    2009-01-01

    Fully kinetic-particle simulations and hybrid simulations have been utilized for decades to investigate various fundamental plasma processes, such as magnetic reconnection, fast compressional waves, and wave-particle interaction. Nevertheless, due to disparate temporal and spatial scales between electrons and ions, existing fully kinetic-particle codes have to employ either unrealistically high electron-to-ion mass ratio, me/mi, or simulation domain limited to a few or a few ten's of the ion Larmor radii, or/and time much less than the global Alfven time scale in order to accommodate available computing resources. On the other hand, in the hybrid simulation, the ions are treated as fully kinetic particles but the electrons are treated as a massless fluid. The electron kinetic effects, e.g., wave-particle resonances and finite electron Larmor radius effects, are completely missing. Important physics, such as the electron transit time damping of fast compressional waves or the triggering mechanism of magnetic reconnection in collisionless plasmas is absent in the hybrid codes. Motivated by these considerations and noting that dynamics of interest to us has frequencies lower than the electron gyrofrequency, we planned to develop an innovative particle simulation model, gyrokinetic (GK) electrons and fully kinetic (FK) ions. In the GK-electron and FK-ion (GKe/FKi) particle simulation model, the rapid electron cyclotron motion is removed, while keeping finite electron Larmor radii, realistic me/mi ratio, wave-particle interactions, and off-diagonal components of electron pressure tensor. The computation power can thus be significantly improved over that of the full-particle codes. As planned in the project DE-FG02-05ER54826, we have finished the development of the new GK-electron and FK-ion scheme, finished its benchmark for a uniform plasma in 1-D, 2-D, and 3-D systems against linear waves obtained from analytical theories, and carried out a further convergence test

  15. Modeling the electron-proton telescope on Solar Orbiter

    Energy Technology Data Exchange (ETDEWEB)

    Boden, Sebastian; Steinhagen, Jan; Kulkarni, S.R.; Tammen, Jan; Elftmann, Robert; Martin, Cesar; Ravanbakhsh, Ali; Boettcher, Stephan; Seimetz, Lars; Wimmer-Schweingruber, Robert F. [Christian-Albrechts-Universitaet, Kiel (Germany)

    2014-07-01

    The Electron Proton Telescope (EPT) is one of four sensors in the Energetic Particle Detector suite for Solar Orbiter. It investigates low energy electrons and protons of solar events in an energy range from 20 - 400 keV for electrons and 20 keV - 7 MeV for protons. It distinguishes electrons from protons using a magnet/foil technique with silicon detectors. There will be two EPT units, each with double-barreled telescopes, one looking sunwards/antisunwards and the other north/south. We set up a Monte Carlo model of EPT using the GEANT4 framework, which we can use to simulate interactions of energetic particles in the sensor. Here we present simulation results of the energy coverage for different ion species, and we study how it is possible to distinguish between them.

  16. Angle selective backscattered electron contrast in the low-voltage scanning electron microscope: Simulation and experiment for polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Q., E-mail: qwan2@sheffield.ac.uk [Department of Material Science and Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Masters, R.C. [Department of Material Science and Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Lidzey, D. [Department of Physics and Astronomy, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Abrams, K.J. [Department of Material Science and Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Dapor, M. [European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT-FBK) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), via Sommarive 18, I-38123 Trento (Italy); Plenderleith, R.A. [Department of Material Science and Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Rimmer, S. [Department of Chemistry, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Claeyssens, F.; Rodenburg, C. [Department of Material Science and Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom)

    2016-12-15

    Recently developed detectors can deliver high resolution and high contrast images of nanostructured carbon based materials in low voltage scanning electron microscopes (LVSEM) with beam deceleration. Monte Carlo Simulations are also used to predict under which exact imaging conditions purely compositional contrast can be obtained and optimised. This allows the prediction of the electron signal intensity in angle selective conditions for back-scattered electron (BSE) imaging in LVSEM and compares it to experimental signals. Angle selective detection with a concentric back scattered (CBS) detector is considered in the model in the absence and presence of a deceleration field, respectively. The validity of the model prediction for both cases was tested experimentally for amorphous C and Cu and applied to complex nanostructured carbon based materials, namely a Poly(N-isopropylacrylamide)/Poly(ethylene glycol) Diacrylate (PNIPAM/PEGDA) semi-interpenetration network (IPN) and a Poly(3-hexylthiophene-2,5-diyl) (P3HT) film, to map nano-scale composition and crystallinity distribution by avoiding experimental imaging conditions that lead to a mixed topographical and compositional contrast - Highlights: • An optimised model for nano-scale analysis of beam sensitive materials by LVSEM. • Simulation and separation of composition and topography in a CBS detector. • Selective angle backscattered electron collection for mapping of polymers.

  17. Angle selective backscattered electron contrast in the low-voltage scanning electron microscope: Simulation and experiment for polymers

    International Nuclear Information System (INIS)

    Wan, Q.; Masters, R.C.; Lidzey, D.; Abrams, K.J.; Dapor, M.; Plenderleith, R.A.; Rimmer, S.; Claeyssens, F.; Rodenburg, C.

    2016-01-01

    Recently developed detectors can deliver high resolution and high contrast images of nanostructured carbon based materials in low voltage scanning electron microscopes (LVSEM) with beam deceleration. Monte Carlo Simulations are also used to predict under which exact imaging conditions purely compositional contrast can be obtained and optimised. This allows the prediction of the electron signal intensity in angle selective conditions for back-scattered electron (BSE) imaging in LVSEM and compares it to experimental signals. Angle selective detection with a concentric back scattered (CBS) detector is considered in the model in the absence and presence of a deceleration field, respectively. The validity of the model prediction for both cases was tested experimentally for amorphous C and Cu and applied to complex nanostructured carbon based materials, namely a Poly(N-isopropylacrylamide)/Poly(ethylene glycol) Diacrylate (PNIPAM/PEGDA) semi-interpenetration network (IPN) and a Poly(3-hexylthiophene-2,5-diyl) (P3HT) film, to map nano-scale composition and crystallinity distribution by avoiding experimental imaging conditions that lead to a mixed topographical and compositional contrast - Highlights: • An optimised model for nano-scale analysis of beam sensitive materials by LVSEM. • Simulation and separation of composition and topography in a CBS detector. • Selective angle backscattered electron collection for mapping of polymers.

  18. Statistical 3D damage accumulation model for ion implant simulators

    CERN Document Server

    Hernandez-Mangas, J M; Enriquez, L E; Bailon, L; Barbolla, J; Jaraiz, M

    2003-01-01

    A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided.

  19. Statistical 3D damage accumulation model for ion implant simulators

    International Nuclear Information System (INIS)

    Hernandez-Mangas, J.M.; Lazaro, J.; Enriquez, L.; Bailon, L.; Barbolla, J.; Jaraiz, M.

    2003-01-01

    A statistical 3D damage accumulation model, based on the modified Kinchin-Pease formula, for ion implant simulation has been included in our physically based ion implantation code. It has only one fitting parameter for electronic stopping and uses 3D electron density distributions for different types of targets including compound semiconductors. Also, a statistical noise reduction mechanism based on the dose division is used. The model has been adapted to be run under parallel execution in order to speed up the calculation in 3D structures. Sequential ion implantation has been modelled including previous damage profiles. It can also simulate the implantation of molecular and cluster projectiles. Comparisons of simulated doping profiles with experimental SIMS profiles are presented. Also comparisons between simulated amorphization and experimental RBS profiles are shown. An analysis of sequential versus parallel processing is provided

  20. Simulations of Large-Area Electron Beam Diodes

    Science.gov (United States)

    Swanekamp, S. B.; Friedman, M.; Ludeking, L.; Smithe, D.; Obenschain, S. P.

    1999-11-01

    Large area electron beam diodes are typically used to pump the amplifiers of KrF lasers. Simulations of large-area electron beam diodes using the particle-in-cell code MAGIC3D have shown the electron flow in the diode to be unstable. Since this instability can potentially produce a non-uniform current and energy distribution in the hibachi structure and lasing medium it can be detrimental to laser efficiency. These results are similar to simulations performed using the ISIS code.(M.E. Jones and V.A. Thomas, Proceedings of the 8^th) International Conference on High-Power Particle Beams, 665 (1990). We have identified the instability as the so called ``transit-time" instability(C.K. Birdsall and W.B. Bridges, Electrodynamics of Diode Regions), (Academic Press, New York, 1966).^,(T.M. Antonsen, W.H. Miner, E. Ott, and A.T. Drobot, Phys. Fluids 27), 1257 (1984). and have investigated the role of the applied magnetic field and diode geometry. Experiments are underway to characterize the instability on the Nike KrF laser system and will be compared to simulation. Also some possible ways to mitigate the instability will be presented.

  1. A model for plasma discharges simulation in Tokamak devices

    International Nuclear Information System (INIS)

    Fonseca, Antonio M.M.; Silva, Ruy P. da; Galvao, Ricardo M.O.; Kusnetzov, Yuri; Nascimento, I.C.; Cuevas, Nelson

    2001-01-01

    In this work, a 'zero-dimensional' model for simulation of discharges in Tokamak machine is presented. The model allows the calculation of the time profiles of important parameters of the discharge. The model was applied to the TCABR Tokamak to study the influence of parameters and physical processes during the discharges. Basically it is constituted of five differential equations: two related to the primary and secondary circuits of the ohmic heating transformer and the other three conservation equations of energy, charge and neutral particles. From the physical model, a computer program has been built with the objective of obtaining the time profiles of plasma current, the current in the primary of the ohmic heating transformer, the electronic temperature, the electronic density and the neutral particle density. It was also possible, with the model, to simulate the effects of gas puffing during the shot. The results of the simulation were compared with the experimental results obtained in the TCABR Tokamak, using hydrogen gas

  2. Plasma simulation of electron avalanche in a linear thyratron

    International Nuclear Information System (INIS)

    Kushner, M.J.

    1985-01-01

    Thyratrons typically operate at sufficiently small PD (pressure x electrode separation) that holdoff is obtained by operating on the near side of the Paschen curve, and by shielding the slot in the control grid so there is no straight line path for electrons to reach the anode from the cathode. Electron avalanche is initiated by pulsing the control grid to a high voltage. Upon collapse of voltage in the cathode-control grid space, the discharge is sustained by penetration of potential through the control grid slot into the cathode-control grid region. To better understand the electron avalanche process in multi-grid and slotted structures such as thyratrons, a plasma simulation code has been constructed. This effort is in support of a companion program in which a linear thyratron is being electrically and spectroscopically characterized

  3. Simulation and analysis of secondary emission microwave electron gun

    International Nuclear Information System (INIS)

    He Wencan; Pei Yuanji; Jin Kai; Wu Congfeng

    2001-01-01

    The development of high-current, short-duration pulses of electrons has been a challenging problem for many year. Micro-pulse-gun (MPG) is a novel concept that employs the resonant amplification of an electron current by secondary electron emission in a RE cavity. Using the computation code URMEL-T, several kinds of RF cavities under the frequency of 2856 MHz were calculated and optimized, the magnetic and electric field distribution in them were got. Through particle-in-cell (PIC) simulation, the self-bunching process in a MPG was proved, the relationship between the cavity length and selected phase and the relationship between the peak electric field and selected phase were got. With cathode material of high secondary emission coefficient, the MPG can produce high current densities (1132-5303 A/cm 2 ) and short pulses (3.15-10 ps)

  4. Modeling electron beam parameters and plasma interface position in an anode plasma electron gun with hydrogen atmosphere

    Science.gov (United States)

    Krauze, A.; Virbulis, J.; Kravtsov, A.

    2018-05-01

    A beam glow discharge based electron gun can be applied as heater for silicon crystal growth systems in which silicon rods are pulled from melt. Impacts of high-energy charged particles cause wear and tear of the gun and generate an additional source of silicon contamination. A steady-state model for electron beam formation has been developed to model the electron gun and optimize its design. Description of the model and first simulation results are presented. It has been shown that the model can simulate dimensions of particle impact areas on the cathode and anode, but further improvements of the model are needed to correctly simulate electron trajectory distribution in the beam and the beam current dependence on the applied gas pressure.

  5. Galaxy Alignments: Theory, Modelling & Simulations

    Science.gov (United States)

    Kiessling, Alina; Cacciato, Marcello; Joachimi, Benjamin; Kirk, Donnacha; Kitching, Thomas D.; Leonard, Adrienne; Mandelbaum, Rachel; Schäfer, Björn Malte; Sifón, Cristóbal; Brown, Michael L.; Rassat, Anais

    2015-11-01

    The shapes of galaxies are not randomly oriented on the sky. During the galaxy formation and evolution process, environment has a strong influence, as tidal gravitational fields in the large-scale structure tend to align nearby galaxies. Additionally, events such as galaxy mergers affect the relative alignments of both the shapes and angular momenta of galaxies throughout their history. These "intrinsic galaxy alignments" are known to exist, but are still poorly understood. This review will offer a pedagogical introduction to the current theories that describe intrinsic galaxy alignments, including the apparent difference in intrinsic alignment between early- and late-type galaxies and the latest efforts to model them analytically. It will then describe the ongoing efforts to simulate intrinsic alignments using both N-body and hydrodynamic simulations. Due to the relative youth of this field, there is still much to be done to understand intrinsic galaxy alignments and this review summarises the current state of the field, providing a solid basis for future work.

  6. PGOPHER: A program for simulating rotational, vibrational and electronic spectra

    International Nuclear Information System (INIS)

    Western, Colin M.

    2017-01-01

    The PGOPHER program is a general purpose program for simulating and fitting molecular spectra, particularly the rotational structure. The current version can handle linear molecules, symmetric tops and asymmetric tops and many possible transitions, both allowed and forbidden, including multiphoton and Raman spectra in addition to the common electric dipole absorptions. Many different interactions can be included in the calculation, including those arising from electron and nuclear spin, and external electric and magnetic fields. Multiple states and interactions between them can also be accounted for, limited only by available memory. Fitting of experimental data can be to line positions (in many common formats), intensities or band contours and the parameters determined can be level populations as well as rotational constants. PGOPHER is provided with a powerful and flexible graphical user interface to simplify many of the tasks required in simulating, understanding and fitting molecular spectra, including Fortrat diagrams and energy level plots in addition to overlaying experimental and simulated spectra. The program is open source, and can be compiled with open source tools. This paper provides a formal description of the operation of version 9.1. - Highlights: • Easy-to-use graphical interface for assigning and understanding molecular spectra. • Simulates rotational and vibrational structure of many types of molecular spectra. • Fits molecular properties to line positions or spectral contours. • Handles linear molecules and symmetric and asymmetric tops. • Handles perturbations, nuclear and electron spin, and electric and magnetic fields.

  7. Effective electron-electron and electron-phonon interactions in the Hubbard-Holstein model

    International Nuclear Information System (INIS)

    Aprea, G.; Di Castro, C.; Grilli, M. . E-mail marco.grilli@roma1.infn.it; Lorenzana, J.

    2006-01-01

    We investigate the interplay between the electron-electron and the electron-phonon interaction in the Hubbard-Holstein model. We implement the flow-equation method to investigate within this model the effect of correlation on the electron-phonon effective coupling and, conversely, the effect of phonons in the effective electron-electron interaction. Using this technique we obtain analytical momentum-dependent expressions for the effective couplings and we study their behavior for different physical regimes. In agreement with other works on this subject, we find that the electron-electron attraction mediated by phonons in the presence of Hubbard repulsion is peaked at low transferred momenta. The role of the characteristic energies involved is also analyzed

  8. Particle-in-cell simulations of plasma accelerators and electron-neutral collisions

    Directory of Open Access Journals (Sweden)

    David L. Bruhwiler

    2001-10-01

    Full Text Available We present 2D simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented particle-in-cell code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low \\(∼10^{16} W/cm^{2}\\ and high \\(∼10^{18} W/cm^{2}\\ peak intensity laser pulses are conducted in slab geometry, showing agreement with theory and fluid simulations. Simulations of the E-157 beam wakefield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are conducted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications to XOOPIC required by this work, and summarize the issues relevant to modeling relativistic electron-neutral collisions in a particle-in-cell code.

  9. Simulations of Electron Cloud Effects on the Beam Dynamics for the FNAL Main Injector Upgrade

    International Nuclear Information System (INIS)

    Sonnad Kiran G.; Furman, Miguel; Vay, Jean-Luc; Venturini, Marco; Celata, Christine M.; Grote, David

    2006-01-01

    The Fermilab main injector (MI) is being considered for an upgrade as part of the high intensity neutrino source (HINS) effort. This upgrade will involve a significant increasing of the bunch intensity relative to its present value. Such an increase will place the MI in a regime in which electron-cloud effects are expected to become important. We have used the electrostatic particle-in-cell code WARP, recently augmented with new modeling capabilities and simulation techniques, to study the dynamics of beam-electron cloud interaction. This work in progress involves a systematic assessment of beam instabilities due to the presence of electron clouds

  10. Simulation Study of Electronic Damping of Microphonic Vibrations in Superconducting Cavities

    International Nuclear Information System (INIS)

    Alicia Hofler; Jean Delayen

    2005-01-01

    Electronic damping of microphonic vibrations in superconducting rf cavities involves an active modulation of the cavity field amplitude in order to induce ponderomotive forces that counteract the effect of ambient vibrations on the cavity frequency. In lightly beam loaded cavities, a reduction of the microphonics-induced frequency excursions leads directly to a reduction of the rf power required for phase and amplitude stabilization. Jefferson Lab is investigating such an electronic damping scheme that could be applied to the JLab 12 GeV upgrade, the RIA driver, and possibly to energy-recovering superconducting linacs. This paper discusses a model and presents simulation results for electronic damping of microphonic vibrations

  11. Simulations of the electron cloud buildup and its influence on the microwave transmission measurement

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Oliver Sebastian, E-mail: o.haas@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Boine-Frankenheim, Oliver [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Schlossgartenstraße 8, 64289 Darmstadt (Germany); Petrov, Fedor [Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Schlossgartenstraße 8, 64289 Darmstadt (Germany)

    2013-11-21

    An electron cloud density in an accelerator can be measured using the Microwave Transmission (MWT) method. The aim of our study is to evaluate the influence of a realistic, nonuniform electron cloud on the MWT. We conduct electron cloud buildup simulations for beam pipe geometries and bunch parameters resembling roughly the conditions in the CERN SPS. For different microwave waveguide modes the phase shift induced by a known electron cloud density is obtained from three different approaches: 3D Particle-In-Cell (PIC) simulation of the electron response, a 2D eigenvalue solver for waveguide modes assuming a dielectric response function for cold electrons, a perturbative method assuming a sufficiently smooth density profile. While several electron cloud parameters, such as temperature, result in minor errors in the determined density, the transversely inhomogeneous density can introduce a large error in the measured electron density. We show that the perturbative approach is sufficient to describe the phase shift under realistic electron cloud conditions. Depending on the geometry of the beam pipe, the external magnetic field configuration and the used waveguide mode, the electron cloud density can be concentrated at the beam pipe or near the beam pipe center, leading to a severe over- or underestimation of the electron density. -- Author-Highlights: •Electron cloud distributions are very inhomogeneous, especially in dipoles. •These inhomogeneities affect the microwave transmission measurement results. •Electron density might be over- or underestimated, depending on setup. •This can be quantified with several models, e.g. a perturbative approach.

  12. Refinement of Monte Carlo simulations of electron-specimen interaction in low-voltage SEM

    International Nuclear Information System (INIS)

    Kieft, Erik; Bosch, Eric

    2008-01-01

    A Monte Carlo tool is presented for the simulation of secondary electron (SE) emission in a scanning electron microscope (SEM). The tool is based on the Geant4 platform of CERN. The modularity of this platform makes it comparatively easy to add and test individual physical models. Our aim has been to develop a flexible and generally applicable tool, while at the same time including a good description of low-energy (<50 eV) interactions of electrons with matter. To this end we have combined Mott cross-sections with phonon-scattering based cross-sections for the elastic scattering of electrons, and we have adopted a dielectric function theory approach for inelastic scattering and generation of SEs. A detailed model of the electromagnetic fields from an actual SEM column has been included in the tool for ray tracing of secondary and backscattered electrons. Our models have been validated against experimental results through comparison of the simulation results with experimental yields, SE spectra and SEM images. It is demonstrated that the resulting simulation package is capable of quantitatively predicting experimental SEM images and is an important tool in building a deeper understanding of SEM imaging.

  13. Validation Test of Geant4 Simulation of Electron Backscattering

    CERN Document Server

    Kim, Sung Hun; Basaglia, Tullio; Han, Min Cheol; Hoff, Gabriela; Kim, Chan Hyeong; Saracco, Paolo

    2015-01-01

    Backscattering is a sensitive probe of the accuracy of electron scattering algorithms implemented in Monte Carlo codes. The capability of the Geant4 toolkit to describe realistically the fraction of electrons backscattered from a target volume is extensively and quantitatively evaluated in comparison with experimental data retrieved from the literature. The validation test covers the energy range between approximately 100 eV and 20 MeV, and concerns a wide set of target elements. Multiple and single electron scattering models implemented in Geant4, as well as preassembled selections of physics models distributed within Geant4, are analyzed with statistical methods. The evaluations concern Geant4 versions from 9.1 to 10.1. Significant evolutions are observed over the range of Geant4 versions, not always in the direction of better compatibility with experiment. Goodness-of-fit tests complemented by categorical analysis tests identify a configuration based on Geant4 Urban multiple scattering model in Geant4 vers...

  14. THE MARK I BUSINESS SYSTEM SIMULATION MODEL

    Science.gov (United States)

    of a large-scale business simulation model as a vehicle for doing research in management controls. The major results of the program were the...development of the Mark I business simulation model and the Simulation Package (SIMPAC). SIMPAC is a method and set of programs facilitating the construction...of large simulation models. The object of this document is to describe the Mark I Corporation model, state why parts of the business were modeled as they were, and indicate the research applications of the model. (Author)

  15. Characterization of electron temperature by simulating a multicusp ion source

    Energy Technology Data Exchange (ETDEWEB)

    Yeon, Yeong Heum [Sungkyunkwan University, WCU Department of Energy Science, 2066, Seobu-ro, Jangan-gu, Suwon-si (Korea, Republic of); Ghergherehchi, Mitra; Kim, Sang Bum; Jun, Woo Jung [Sungkyunkwan University, School of Information & Communication Engineering, 2066, Seobu-ro, Jangan-gu, Suwon-si (Korea, Republic of); Lee, Jong Chul; Mohamed Gad, Khaled Mohamed [Sungkyunkwan University, WCU Department of Energy Science, 2066, Seobu-ro, Jangan-gu, Suwon-si (Korea, Republic of); Namgoong, Ho [Sungkyunkwan University, School of Information & Communication Engineering, 2066, Seobu-ro, Jangan-gu, Suwon-si (Korea, Republic of); Chai, Jong Seo, E-mail: jschai@skku.edu [Sungkyunkwan University, School of Information & Communication Engineering, 2066, Seobu-ro, Jangan-gu, Suwon-si (Korea, Republic of)

    2016-12-01

    Multicusp ion sources are used in cyclotrons and linear accelerators to produce high beam currents. The structure of a multicusp ion source consists of permanent magnets, filaments, and an anode body. The configuration of the array of permanent magnets, discharge voltage of the plasma, extraction bias voltage, and structure of the multicusp ion source body decide the quality of the beam. The electrons are emitted from the filament by thermionic emission. The emission current can be calculated from thermal information pertaining to the filament, and from the applied voltage and current. The electron trajectories were calculated using CST Particle Studio to optimize the plasma. The array configuration of the permanent magnets decides the magnetic field inside the ion source. The extraction bias voltage and the structure of the multicusp ion source body decide the electric field. Optimization of the electromagnetic field was performed with these factors. CST Particle Studio was used to calculate the electron temperature with a varying permanent magnet array. Four types of permanent magnet array were simulated to optimize the electron temperature. It was found that a 2-layer full line cusp field (with inverse field) produced the best electron temperature control behavior.

  16. Distributed simulation a model driven engineering approach

    CERN Document Server

    Topçu, Okan; Oğuztüzün, Halit; Yilmaz, Levent

    2016-01-01

    Backed by substantive case studies, the novel approach to software engineering for distributed simulation outlined in this text demonstrates the potent synergies between model-driven techniques, simulation, intelligent agents, and computer systems development.

  17. Density-dependent electron transport and precise modeling of GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Bajaj, Sanyam, E-mail: bajaj.10@osu.edu; Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Reza, Shahed; Chumbes, Eduardo M. [Raytheon Integrated Defense Systems, Andover, Massachusetts 01810 (United States); Khurgin, Jacob [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Material Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-10-12

    We report on the direct measurement of two-dimensional sheet charge density dependence of electron transport in AlGaN/GaN high electron mobility transistors (HEMTs). Pulsed IV measurements established increasing electron velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 10{sup 7 }cm/s at a low sheet charge density of 7.8 × 10{sup 11 }cm{sup −2}. An optical phonon emission-based electron velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the electron velocity with strong electron-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs.

  18. Density-dependent electron transport and precise modeling of GaN high electron mobility transistors

    International Nuclear Information System (INIS)

    Bajaj, Sanyam; Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang; Reza, Shahed; Chumbes, Eduardo M.; Khurgin, Jacob; Rajan, Siddharth

    2015-01-01

    We report on the direct measurement of two-dimensional sheet charge density dependence of electron transport in AlGaN/GaN high electron mobility transistors (HEMTs). Pulsed IV measurements established increasing electron velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 10 7  cm/s at a low sheet charge density of 7.8 × 10 11  cm −2 . An optical phonon emission-based electron velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the electron velocity with strong electron-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs

  19. Benchmark simulation models, quo vadis?

    Science.gov (United States)

    Jeppsson, U; Alex, J; Batstone, D J; Benedetti, L; Comas, J; Copp, J B; Corominas, L; Flores-Alsina, X; Gernaey, K V; Nopens, I; Pons, M-N; Rodríguez-Roda, I; Rosen, C; Steyer, J-P; Vanrolleghem, P A; Volcke, E I P; Vrecko, D

    2013-01-01

    As the work of the IWA Task Group on Benchmarking of Control Strategies for wastewater treatment plants (WWTPs) is coming to an end, it is essential to disseminate the knowledge gained. For this reason, all authors of the IWA Scientific and Technical Report on benchmarking have come together to provide their insights, highlighting areas where knowledge may still be deficient and where new opportunities are emerging, and to propose potential avenues for future development and application of the general benchmarking framework and its associated tools. The paper focuses on the topics of temporal and spatial extension, process modifications within the WWTP, the realism of models, control strategy extensions and the potential for new evaluation tools within the existing benchmark system. We find that there are major opportunities for application within all of these areas, either from existing work already being done within the context of the benchmarking simulation models (BSMs) or applicable work in the wider literature. Of key importance is increasing capability, usability and transparency of the BSM package while avoiding unnecessary complexity.

  20. Simulation modelling of fynbos ecosystems: Systems analysis and conceptual models

    CSIR Research Space (South Africa)

    Kruger, FJ

    1985-03-01

    Full Text Available -animal interactions. An additional two models, which expand aspects of the FYNBOS model, are described: a model for simulating canopy processes; and a Fire Recovery Simulator. The canopy process model will simulate ecophysiological processes in more detail than FYNBOS...

  1. Simulating Ru L 3 -Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  2. Status of Galileo interim radiation electron model

    Science.gov (United States)

    Garrett, H. B.; Jun, I.; Ratliff, J. M.; Evans, R. W.; Clough, G. A.; McEntire, R. W.

    2003-01-01

    Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EDP) were used to develop a new model of Jupiter's trapped electron radiation in the jovian equatorial plane for the range 8 to 16 Jupiter radii.

  3. An Electronic Publishing Model for Academic Publishers.

    Science.gov (United States)

    Gold, Jon D.

    1994-01-01

    Describes an electronic publishing model based on Standard Generalized Markup Language (SGML) and considers its use by an academic publisher. Highlights include how SGML is used to produce an electronic book, hypertext, methods of delivery, intellectual property rights, and future possibilities. Sample documents are included. (two references) (LRW)

  4. Modelling and simulation of superalloys. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Rogal, Jutta; Hammerschmidt, Thomas; Drautz, Ralf (eds.)

    2014-07-01

    Superalloys are multi-component materials with complex microstructures that offer unique properties for high-temperature applications. The complexity of the superalloy materials makes it particularly challenging to obtain fundamental insight into their behaviour from the atomic structure to turbine blades. Recent advances in modelling and simulation of superalloys contribute to a better understanding and prediction of materials properties and therefore offer guidance for the development of new alloys. This workshop will give an overview of recent progress in modelling and simulation of materials for superalloys, with a focus on single crystal Ni-base and Co-base alloys. Topics will include electronic structure methods, atomistic simulations, microstructure modelling and modelling of microstructural evolution, solidification and process simulation as well as the modelling of phase stability and thermodynamics.

  5. Optimisation of electron beam characteristics by simulated annealing

    International Nuclear Information System (INIS)

    Ebert, M.A.; University of Adelaide, SA; Hoban, P.W.

    1996-01-01

    Full text: With the development of technology in the field of treatment beam delivery, the possibility of tailoring radiation beams (via manipulation of the beam's phase space) is foreseeable. This investigation involved evaluating a method for determining the characteristics of pure electron beams which provided dose distributions that best approximated desired distributions. The aim is to determine which degrees of freedom are advantageous and worth pursuing in a clinical setting. A simulated annealing routine was developed to determine optimum electron beam characteristics. A set of beam elements are defined at the surface of a homogeneous water equivalent phantom defining discrete positions and angles of incidence, and electron energies. The optimal weighting of these elements is determined by the (generally approximate) solution to the linear equation, Dw = d, where d represents the dose distribution calculated over the phantom, w the vector of (50 - 2x10 4 ) beam element relative weights, and D a normalised matrix of dose deposition kernels. In the iterative annealing procedure, beam elements are randomly selected and beam weighting distributions are sampled and used to perturb the selected elements. Perturbations are accepted or rejected according to standard simulated annealing criteria. The result (after the algorithm has terminated due to meeting an iteration or optimisation specification) is an approximate solution for the beam weight vector (w) specified by the above equation. This technique has been applied for several sample dose distributions and phase space restrictions. An example is given of the phase space obtained when endeavouring to conform to a rectangular 100% dose region with polyenergetic though normally incident electrons. For regular distributions, intuitive conclusions regarding the benefits of energy/angular manipulation may be made, whereas for complex distributions, variations in intensity over beam elements of varying energy and

  6. Xyce Parallel Electronic Simulator Reference Guide Version 6.7.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aadithya, Karthik Venkatraman [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schiek, Richard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Verley, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    This document is a reference guide to the Xyce Parallel Electronic Simulator, and is a companion document to the Xyce Users' Guide [1] . The focus of this document is (to the extent possible) exhaustively list device parameters, solver options, parser options, and other usage details of Xyce . This document is not intended to be a tutorial. Users who are new to circuit simulation are better served by the Xyce Users' Guide [1] . The information herein is subject to change without notice. Copyright c 2002-2017 Sandia Corporation. All rights reserved. Trademarks Xyce TM Electronic Simulator and Xyce TM are trademarks of Sandia Corporation. Orcad, Orcad Capture, PSpice and Probe are registered trademarks of Cadence Design Systems, Inc. Microsoft, Windows and Windows 7 are registered trademarks of Microsoft Corporation. Medici, DaVinci and Taurus are registered trademarks of Synopsys Corporation. Amtec and TecPlot are trademarks of Amtec Engineering, Inc. All other trademarks are property of their respective owners. Contacts World Wide Web http://xyce.sandia.gov https://info.sandia.gov/xyce (Sandia only) Email xyce@sandia.gov (outside Sandia) xyce-sandia@sandia.gov (Sandia only) Bug Reports (Sandia only) http://joseki-vm.sandia.gov/bugzilla http://morannon.sandia.gov/bugzilla

  7. Theory, simulation and experiments for precise deflection control of radiotherapy electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, R.; Leiva, J.; Moncada, R.; Rojas, L.; Santibanez, M.; Valente, M.; Young, H. [Universidad de la Frontera, Centro de Fisica e Ingenieria en Medicina, Av. Francisco Salazar 1145, Casilla 54-D, Temuco (Chile); Velasquez, J. [Universidad de la Frontera, Departamento de Ciencias Fisicas, Av. Francisco Salazar 1145, Casilla 54-D, Temuco (Chile); Zelada, G. [Clinica Alemana de Santiago, Av. Vitacura 5951, 13132 Vitacura, Santiago (Chile); Astudillo, R., E-mail: rodolfo.figueroa@ufrontera.cl [Hospital Base de Valdivia, C. Simpson 850, XIV Region de los Rios, Valdivia (Chile)

    2017-10-15

    Conventional radiotherapy is mainly applied by linear accelerators. Although linear accelerators provide dual (electron/photon) radiation beam modalities, both of them are intrinsically produced by a megavoltage electron current. Modern radiotherapy treatment techniques are based on suitable devices inserted or attached to conventional linear accelerators. Thus, precise control of delivered beam becomes a main key issue. This work presents an integral description of electron beam deflection control as required for novel radiotherapy technique based on convergent photon beam production. Theoretical and Monte Carlo approaches were initially used for designing and optimizing devices components. Then, dedicated instrumentation was developed for experimental verification of electron beam deflection due to the designed magnets. Both Monte Carlo simulations and experimental results support the reliability of electrodynamics models used for predict megavoltage electron beam control. (Author)

  8. Theory, simulation and experiments for precise deflection control of radiotherapy electron beams

    International Nuclear Information System (INIS)

    Figueroa, R.; Leiva, J.; Moncada, R.; Rojas, L.; Santibanez, M.; Valente, M.; Young, H.; Velasquez, J.; Zelada, G.; Astudillo, R.

    2017-10-01

    Conventional radiotherapy is mainly applied by linear accelerators. Although linear accelerators provide dual (electron/photon) radiation beam modalities, both of them are intrinsically produced by a megavoltage electron current. Modern radiotherapy treatment techniques are based on suitable devices inserted or attached to conventional linear accelerators. Thus, precise control of delivered beam becomes a main key issue. This work presents an integral description of electron beam deflection control as required for novel radiotherapy technique based on convergent photon beam production. Theoretical and Monte Carlo approaches were initially used for designing and optimizing devices components. Then, dedicated instrumentation was developed for experimental verification of electron beam deflection due to the designed magnets. Both Monte Carlo simulations and experimental results support the reliability of electrodynamics models used for predict megavoltage electron beam control. (Author)

  9. The electron beam dynamics simulation in the laser-electron storage ring involving compton and intrabeam scattering

    International Nuclear Information System (INIS)

    Gladkikh, P.I.; Telegin, Yu.N.; Karnaukhov, I.M.

    2002-01-01

    The feasibility of the development of intense X-ray sources based on Compton scattering in laser-electron storage rings is discussed. The results of the electron beam dynamics simulation involving Compton and intrabeam scattering are presented

  10. The electron beam dynamics simulation in the laser-electron storage ring involving compton and intrabeam scattering

    CERN Document Server

    Gladkikh, P I; Karnaukhov, I M

    2002-01-01

    The feasibility of the development of intense X-ray sources based on Compton scattering in laser-electron storage rings is discussed. The results of the electron beam dynamics simulation involving Compton and intrabeam scattering are presented.

  11. Calibration of Monte Carlo simulation code to low voltage electron beams through radiachromic dosimetry

    International Nuclear Information System (INIS)

    Weiss, D.E.; Kalweit, H.W.; Kensek, R.P.

    1994-01-01

    A simple multilayer slab model of an electron beam using the ITS/TIGER code can consistently account for about 80% of the actual dose delivered by a low voltage electron beam. The difference in calculated values is principally due to the 3D hibachi structure which blocks 22% of the beam. A 3D model was constructed using the ITS/ACCEPT code to improve upon the TIGER simulations. A rectangular source description update to the code and reproduction of all key geometric elements involved, including the hibachi, accounted for 90-95% of the dose received by routine dosimetry

  12. IrPd nanoalloys: simulations, from surface segregation to local electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Andriamiharintsoa, T. H. [Institut de Physique et Chimie des Matériaux de Strasbourg CNRS-UDS UMR 7504 (France); Rakotomahevitra, A. [Institut pour la Maîtrise de l’Énergie, Faculté des sciences d’Antananarivo (Madagascar); Piccolo, L. [Institut de Recherches sur la Catalyse et l’Environnement de Lyon IRCELYON, UMR 5256 CNRS and Université Lyon 1 (France); Goyhenex, C., E-mail: christine.goyhenex@ipcms.unistra.fr [Institut de Physique et Chimie des Matériaux de Strasbourg CNRS-UDS UMR 7504 (France)

    2015-05-15

    Using semi-empirical modeling, namely tight-binding at different levels of accuracy, the chemical, crystallographic, and electronic structures of bimetallic IrPd nanoparticles are characterized. For the purpose, model cuboctahedral particles containing 561 atoms are considered. Atomistic simulations show that core–shell nanoparticles are highly stable, with a strong surface segregation of Pd, at least for one atomic shell thickness. Within self-consistent tight-binding calculations founded on the density functional theory, an accurate insight is given into the electronic structure of these materials which have a high potential as catalysts.

  13. An introduction to enterprise modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ostic, J.K.; Cannon, C.E. [Los Alamos National Lab., NM (United States). Technology Modeling and Analysis Group

    1996-09-01

    As part of an ongoing effort to continuously improve productivity, quality, and efficiency of both industry and Department of Energy enterprises, Los Alamos National Laboratory is investigating various manufacturing and business enterprise simulation methods. A number of enterprise simulation software models are being developed to enable engineering analysis of enterprise activities. In this document the authors define the scope of enterprise modeling and simulation efforts, and review recent work in enterprise simulation at Los Alamos National Laboratory as well as at other industrial, academic, and research institutions. References of enterprise modeling and simulation methods and a glossary of enterprise-related terms are provided.

  14. Simulation and Modeling Methodologies, Technologies and Applications

    CERN Document Server

    Filipe, Joaquim; Kacprzyk, Janusz; Pina, Nuno

    2014-01-01

    This book includes extended and revised versions of a set of selected papers from the 2012 International Conference on Simulation and Modeling Methodologies, Technologies and Applications (SIMULTECH 2012) which was sponsored by the Institute for Systems and Technologies of Information, Control and Communication (INSTICC) and held in Rome, Italy. SIMULTECH 2012 was technically co-sponsored by the Society for Modeling & Simulation International (SCS), GDR I3, Lionphant Simulation, Simulation Team and IFIP and held in cooperation with AIS Special Interest Group of Modeling and Simulation (AIS SIGMAS) and the Movimento Italiano Modellazione e Simulazione (MIMOS).

  15. Structured building model reduction toward parallel simulation

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, Justin R. [Cornell University; Hencey, Brondon M. [Cornell University

    2013-08-26

    Building energy model reduction exchanges accuracy for improved simulation speed by reducing the number of dynamical equations. Parallel computing aims to improve simulation times without loss of accuracy but is poorly utilized by contemporary simulators and is inherently limited by inter-processor communication. This paper bridges these disparate techniques to implement efficient parallel building thermal simulation. We begin with a survey of three structured reduction approaches that compares their performance to a leading unstructured method. We then use structured model reduction to find thermal clusters in the building energy model and allocate processing resources. Experimental results demonstrate faster simulation and low error without any interprocessor communication.

  16. Electron scattering in the interacting boson model

    NARCIS (Netherlands)

    Dieperink, AEL; Iachello, F; Rinat, A; Creswell, C

    1978-01-01

    It is suggested that the interacting boson model be used in the analysis of electron scattering data. Qualitative features of the expected behavior of the inelastic excitation of some 2 ÷ states inthe transitional Sm-Nd region are discussed

  17. Analog electronic model of the lobster pyloric central pattern generator

    Energy Technology Data Exchange (ETDEWEB)

    Volkovskii, A [Institute for Nonlinear Science, University of California San Diego, CA (United States); Brugioni, S [Institute for Nonlinear Science, University of California San Diego, CA (United States); Istituto Nazionale di Ottica Applicata Largo E. Fermi 6 50125 Florence (Italy); Levi, R [Institute for Nonlinear Science, University of California San Diego, CA (United States); Rabinovich, M [Institute for Nonlinear Science, University of California San Diego, CA (United States); Selverston, A [Institute for Nonlinear Science, University of California San Diego, CA (United States); Abarbane, H D I [Institute for Nonlinear Science, University of California San Diego, CA (United States)

    2005-01-01

    An electronic circuit intended to simulate the nonlinear dynamics of a simplified 3-cell model of the pyloric central pattern generator in California spiny lobster stomato gastric ganglion is presented. The model employs the synaptic phase locked loop (SPLL) concept where the frequency of oscillations of a postsynaptic cell is mainly controlled by the synaptic current which depends on the phase shift between the oscillations. The theoretical study showed that the system has a stable steady state with correct phase shifts between the oscillations and that this regime is stable when the frequency of the pacemaker cell is varied over a wide range. The main bifurcations in the system were studied analytically, in computer simulations, and in experiments with the electronic circuit. The experimental measurements are in good agreement with the expectations of the theoretical model.

  18. A physiological production model for cacao : results of model simulations

    NARCIS (Netherlands)

    Zuidema, P.A.; Leffelaar, P.A.

    2002-01-01

    CASE2 is a physiological model for cocoa (Theobroma cacao L.) growth and yield. This report introduces the CAcao Simulation Engine for water-limited production in a non-technical way and presents simulation results obtained with the model.

  19. Simulation and Characterization of a Miniaturized Scanning Electron Microscope

    Science.gov (United States)

    Gaskin, Jessica A.; Jerman, Gregory A.; Medley, Stephanie; Gregory, Don; Abbott, Terry O.; Sampson, Allen R.

    2011-01-01

    A miniaturized Scanning Electron Microscope (mSEM) for in-situ lunar investigations is being developed at NASA Marshall Space Flight Center with colleagues from the University of Alabama in Huntsville (UAH), Advanced Research Systems (ARS), the University of Tennessee in Knoxville (UTK) and Case Western Reserve University (CWRU). This effort focuses on the characterization of individual components of the mSEM and simulation of the complete system. SEMs can provide information on the size, shape, morphology and chemical composition of lunar regolith. Understanding these basic properties will allow us to better estimate the challenges associated with In-Situ Resource Utilization and to improve our basic science knowledge of the lunar surface (either precluding the need for sample return or allowing differentiation of unique samples to be returned to Earth.) The main components of the mSEM prototype includes: a cold field emission electron gun (CFEG), focusing lens, deflection/scanning system and backscatter electron detector. Of these, the electron gun development is of particular importance as it dictates much of the design of the remaining components. A CFEG was chosen for use with the lunar mSEM as its emission does not depend on heating of the tungsten emitter (lower power), it offers a long operation lifetime, is orders of magnitude brighter than tungsten hairpin guns, has a small source size and exhibits low beam energy spread.

  20. Electron sub-cycling in particle simulation of plasma

    International Nuclear Information System (INIS)

    Adam, J.C.; Serveniere, A.G.; Langdon, A.B.

    1982-01-01

    A straightforward modification which reduces by half the computational cost of standard particle-in-cell algorithms for simulation of plasmas is described. The saving is obtained by integrating only the electrons through a number of time steps (sub-cycle) in order to resolve their evolution, while integrating the much slower ions only once per cycle, i.e., to match the time step of each species to their characteristic frequencies. A dispersion relation is derived which describes the numerical instabilities expected by sampling frequency arguments. Simulations support the broad features of the analytical results, viz., the maximum growth rate and domain of the instability, and its stabilization by the addition of weak damping. An implicit sub-cycling algorithm is suggested which may provide further saving while avoiding a limitation of implicit algorithms described elsewhere

  1. Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA)

    Science.gov (United States)

    SRD 100 Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA) (PC database for purchase)   This database has been designed to facilitate quantitative interpretation of Auger-electron and X-ray photoelectron spectra and to improve the accuracy of quantitation in routine analysis. The database contains all physical data needed to perform quantitative interpretation of an electron spectrum for a thin-film specimen of given composition. A simulation module provides an estimate of peak intensities as well as the energy and angular distributions of the emitted electron flux.

  2. Simulation modeling and analysis with Arena

    CERN Document Server

    Altiok, Tayfur

    2007-01-01

    Simulation Modeling and Analysis with Arena is a highly readable textbook which treats the essentials of the Monte Carlo discrete-event simulation methodology, and does so in the context of a popular Arena simulation environment.” It treats simulation modeling as an in-vitro laboratory that facilitates the understanding of complex systems and experimentation with what-if scenarios in order to estimate their performance metrics. The book contains chapters on the simulation modeling methodology and the underpinnings of discrete-event systems, as well as the relevant underlying probability, statistics, stochastic processes, input analysis, model validation and output analysis. All simulation-related concepts are illustrated in numerous Arena examples, encompassing production lines, manufacturing and inventory systems, transportation systems, and computer information systems in networked settings.· Introduces the concept of discrete event Monte Carlo simulation, the most commonly used methodology for modeli...

  3. Kinetic electron model for plasma thruster plumes

    Science.gov (United States)

    Merino, Mario; Mauriño, Javier; Ahedo, Eduardo

    2018-03-01

    A paraxial model of an unmagnetized, collisionless plasma plume expanding into vacuum is presented. Electrons are treated kinetically, relying on the adiabatic invariance of their radial action integral for the integration of Vlasov's equation, whereas ions are treated as a cold species. The quasi-2D plasma density, self-consistent electric potential, and electron pressure, temperature, and heat fluxes are analyzed. In particular, the model yields the collisionless cooling of electrons, which differs from the Boltzmann relation and the simple polytropic laws usually employed in fluid and hybrid PIC/fluid plume codes.

  4. Design of simulated nuclear electronics laboratory experiments based on IAEA-TECDOC-530 on pcs

    International Nuclear Information System (INIS)

    Ghousia, S.F.; Nadeem, M.; Khaleeq, M.T.

    2002-05-01

    In this IAEA project, PK-11089 (Design of Simulated Nuclear Electronics Laboratory Experiments based on IAEA-TECDOC-530 on PCs), a software package consisting of Computer-Simulated Laboratory Experiments on Nuclear Electronics compatible with the IAEA-TECDOC-530 (Nuclear Electronics Laboratory Manual) has been developed in OrCAD 9.0 (an electronic circuit simulation software environment) as a self-training aid. The software process model employed in this project is the Feedback Waterfall model with some Rapid Application Model. The project work is completed in the five phases of the SDLC, (all of them have been fully completed) which includes the Requirement Definition, Phase, System and Software Design, Implementation and Unit testing, Integration and System-testing phase and the Operation and Maintenance phase. A total of 125 circuits are designed in 39 experiments from Power Supplies, Analog circuits, Digital circuits and Multi-channel analyzer sections. There is another set of schematic designs present in the package, which contains faulty circuits. This set is designed for the learners to exercise the troubleshooting. The integration and system-testing phase was carried out simultaneously. The Operation and Maintenance phase has been implemented by accomplishing it through some trainees and some undergraduate engineering students by allowing them to play with the software independently. (author)

  5. Modeling power electronics and interfacing energy conversion systems

    CERN Document Server

    Simões, Marcelo Godoy

    2017-01-01

    Discusses the application of mathematical and engineering tools for modeling, simulation and control oriented for energy systems, power electronics and renewable energy. This book builds on the background knowledge of electrical circuits, control of dc/dc converters and inverters, energy conversion and power electronics. The book shows readers how to apply computational methods for multi-domain simulation of energy systems and power electronics engineering problems. Each chapter has a brief introduction on the theoretical background, a description of the problems to be solved, and objectives to be achieved. Block diagrams, electrical circuits, mathematical analysis or computer code are covered. Each chapter concludes with discussions on what should be learned, suggestions for further studies and even some experimental work.

  6. Low dose CT simulation using experimental noise model

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Satori; Zamyatin, Alexander A. [Toshiba Medical Systems Corporation, Tochigi, Otawarashi (Japan); Silver, Michael D. [Toshiba Medical Research Institute, Vernon Hills, IL (United States)

    2011-07-01

    We suggest a method to obtain system noise model experimentally without relying on assumptions on statistical distribution of the noise; also, knowledge of DAS gain and electronic noise level are not required. Evaluation with ultra-low dose CT data (5 mAs) shows good match between simulated and real data noise. (orig.)

  7. Network Modeling and Simulation A Practical Perspective

    CERN Document Server

    Guizani, Mohsen; Khan, Bilal

    2010-01-01

    Network Modeling and Simulation is a practical guide to using modeling and simulation to solve real-life problems. The authors give a comprehensive exposition of the core concepts in modeling and simulation, and then systematically address the many practical considerations faced by developers in modeling complex large-scale systems. The authors provide examples from computer and telecommunication networks and use these to illustrate the process of mapping generic simulation concepts to domain-specific problems in different industries and disciplines. Key features: Provides the tools and strate

  8. Design and simulation of a ~390 GHz seventh harmonic gyrotron using a large orbit electron beam

    Science.gov (United States)

    Li, Fengping; He, Wenlong; Cross, Adrian W.; Donaldson, Craig R.; Zhang, Liang; Phelps, Alan D. R.; Ronald, Kevin

    2010-04-01

    A ~390 GHz harmonic gyrotron based on a cusp electron gun has been designed and numerically modelled. The gyrotron operates at the seventh harmonic of the electron cyclotron frequency with the beam interacting with a TE71 waveguide mode. Theoretical as well as numerical simulation results using the 3D particle-in-cell code MAGIC are presented. The cusp gun generated an axis-encircling, annular shaped electron beam of energy 40 keV, current 1.5 A with a velocity ratio α of 3. Smooth cylindrical waveguides have been studied as the interaction cavities and their cavity Q optimized for 390 GHz operation. In the simulations ~600 W of output power at the design frequency has been demonstrated.

  9. Modelling and simulation of a heat exchanger

    Science.gov (United States)

    Xia, Lei; Deabreu-Garcia, J. Alex; Hartley, Tom T.

    1991-01-01

    Two models for two different control systems are developed for a parallel heat exchanger. First by spatially lumping a heat exchanger model, a good approximate model which has a high system order is produced. Model reduction techniques are applied to these to obtain low order models that are suitable for dynamic analysis and control design. The simulation method is discussed to ensure a valid simulation result.

  10. Monte Carlo simulation of electron beams from an accelerator head using PENELOPE

    Energy Technology Data Exchange (ETDEWEB)

    Sempau, J. [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain). E-mail: josep.sempau@upc.es; Sanchez-Reyes, A. [Servei d' Oncologia Radioterapica, Hospital Clinic de Barcelona, Villarroel 170, 08036 Barcelona (Spain); Institut d' Investigaciones Biomediques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona (Spain); Salvat, F.; Oulad ben Tahar, H.; Fernandez-Varea, J.M. [Facultat de Fisica (ECM), Universitat de Barcelona, Societat Catalana de Fisica (IEC), Diagonal 647, 08028 Barcelona (Spain); Jiang, S.B. [Department of Radiation Oncology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5304 (United States)

    2001-04-01

    The Monte Carlo code PENELOPE has been used to simulate electron beams from a Siemens Mevatron KDS linac with nominal energies of 6, 12 and 18 MeV. Owing to its accuracy, which stems from that of the underlying physical interaction models, PENELOPE is suitable for simulating problems of interest to the medical physics community. It includes a geometry package that allows the definition of complex quadric geometries, such as those of irradiation instruments, in a straightforward manner. Dose distributions in water simulated with PENELOPE agree well with experimental measurements using a silicon detector and a monitoring ionization chamber. Insertion of a lead slab in the incident beam at the surface of the water phantom produces sharp variations in the dose distributions, which are correctly reproduced by the simulation code. Results from PENELOPE are also compared with those of equivalent simulations with the EGS4-based user codes BEAM and DOSXYZ. Angular and energy distributions of electrons and photons in the phase-space plane (at the downstream end of the applicator) obtained from both simulation codes are similar, although significant differences do appear in some cases. These differences, however, are shown to have a negligible effect on the calculated dose distributions. Various practical aspects of the simulations, such as the calculation of statistical uncertainties and the effect of the 'latent' variance in the phase-space file, are discussed in detail. (author)

  11. Simulations of Electron Transport in Laser Hot Spots

    International Nuclear Information System (INIS)

    Brunner, S.; Valeo, E.

    2001-01-01

    Simulations of electron transport are carried out by solving the Fokker-Planck equation in the diffusive approximation. The system of a single laser hot spot, with open boundary conditions, is systematically studied by performing a scan over a wide range of the two relevant parameters: (1) Ratio of the stopping length over the width of the hot spot. (2) Relative importance of the heating through inverse Bremsstrahlung compared to the thermalization through self-collisions. As for uniform illumination [J.P. Matte et al., Plasma Phys. Controlled Fusion 30 (1988) 1665], the bulk of the velocity distribution functions (VDFs) present a super-Gaussian dependence. However, as a result of spatial transport, the tails are observed to be well represented by a Maxwellian. A similar dependence of the distributions is also found for multiple hot spot systems. For its relevance with respect to stimulated Raman scattering, the linear Landau damping of the electron plasma wave is estimated for such VD Fs. Finally, the nonlinear Fokker-Planck simulations of the single laser hot spot system are also compared to the results obtained with the linear non-local hydrodynamic approach [A.V. Brantov et al., Phys. Plasmas 5 (1998) 2742], thus providing a quantitative limit to the latter method: The hydrodynamic approach presents more than 10% inaccuracy in the presence of temperature variations of the order delta T/T greater than or equal to 1%, and similar levels of deformation of the Gaussian shape of the Maxwellian background

  12. Enhanced quasi-static particle-in-cell simulation of electron cloud instabilities in circular accelerators

    Science.gov (United States)

    Feng, Bing

    Electron cloud instabilities have been observed in many circular accelerators around the world and raised concerns of future accelerators and possible upgrades. In this thesis, the electron cloud instabilities are studied with the quasi-static particle-in-cell (PIC) code QuickPIC. Modeling in three-dimensions the long timescale propagation of beam in electron clouds in circular accelerators requires faster and more efficient simulation codes. Thousands of processors are easily available for parallel computations. However, it is not straightforward to increase the effective speed of the simulation by running the same problem size on an increasingly number of processors because there is a limit to domain size in the decomposition of the two-dimensional part of the code. A pipelining algorithm applied on the fully parallelized particle-in-cell code QuickPIC is implemented to overcome this limit. The pipelining algorithm uses multiple groups of processors and optimizes the job allocation on the processors in parallel computing. With this novel algorithm, it is possible to use on the order of 102 processors, and to expand the scale and the speed of the simulation with QuickPIC by a similar factor. In addition to the efficiency improvement with the pipelining algorithm, the fidelity of QuickPIC is enhanced by adding two physics models, the beam space charge effect and the dispersion effect. Simulation of two specific circular machines is performed with the enhanced QuickPIC. First, the proposed upgrade to the Fermilab Main Injector is studied with an eye upon guiding the design of the upgrade and code validation. Moderate emittance growth is observed for the upgrade of increasing the bunch population by 5 times. But the simulation also shows that increasing the beam energy from 8GeV to 20GeV or above can effectively limit the emittance growth. Then the enhanced QuickPIC is used to simulate the electron cloud effect on electron beam in the Cornell Energy Recovery Linac

  13. Northwestcape-induced Electron Precipitation and Theoretica Simulation

    Science.gov (United States)

    Zhang, Z.; Li, X.; Wang, C.; Chen, L.

    2017-12-01

    Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced > 100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100- 300-keV precipitated-electron behavior, the low energy 30-100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range, in contrast to the 100-300-keVelectronswhichareatL=1.67-1.9. ThisisconsistentwiththeperspectivethattheenergyoftheVLF-waveinducedelectronfluxenhancementdecreaseswithhigherL-shellvalues. Weexpandupontherationalityofthesimultaneous enhancementofthe30-100-and100-300-keVelectronfluxesthroughcomparisonwiththecyclotronresonancetheoryfor the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in northand south hemisphere by ray tracing model. Finally, we present considerable discussionand showthat good agreement exists between the observation of satellites and theory.

  14. E × B electron drift instability in Hall thrusters: Particle-in-cell simulations vs. theory

    Science.gov (United States)

    Boeuf, J. P.; Garrigues, L.

    2018-06-01

    The E × B Electron Drift Instability (E × B EDI), also called Electron Cyclotron Drift Instability, has been observed in recent particle simulations of Hall thrusters and is a possible candidate to explain anomalous electron transport across the magnetic field in these devices. This instability is characterized by the development of an azimuthal wave with wavelength in the mm range and velocity on the order of the ion acoustic velocity, which enhances electron transport across the magnetic field. In this paper, we study the development and convection of the E × B EDI in the acceleration and near plume regions of a Hall thruster using a simplified 2D axial-azimuthal Particle-In-Cell simulation. The simulation is collisionless and the ionization profile is not-self-consistent but rather is given as an input parameter of the model. The aim is to study the development and properties of the instability for different values of the ionization rate (i.e., of the total ion production rate or current) and to compare the results with the theory. An important result is that the wavelength of the simulated azimuthal wave scales as the electron Debye length and that its frequency is on the order of the ion plasma frequency. This is consistent with the theory predicting destruction of electron cyclotron resonance of the E × B EDI in the non-linear regime resulting in the transition to an ion acoustic instability. The simulations also show that for plasma densities smaller than under nominal conditions of Hall thrusters the field fluctuations induced by the E × B EDI are no longer sufficient to significantly enhance electron transport across the magnetic field, and transit time instabilities develop in the axial direction. The conditions and results of the simulations are described in detail in this paper and they can serve as benchmarks for comparisons between different simulation codes. Such benchmarks would be very useful to study the role of numerical noise (numerical

  15. North west cape-induced electron precipitation and theoretical simulation

    Science.gov (United States)

    Zhang, Zhen-xia; Li, Xin-qiao; Wang, Chen-Yu; Chen, Lun-Jin

    2016-11-01

    Enhancement of the electron fluxes in the inner radiation belt, which is induced by the powerful North West Cape (NWC) very-low-frequency (VLF) transmitter, have been observed and analyzed by several research groups. However, all of the previous publications have focused on NWC-induced > 100-keV electrons only, based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Geostationary Operational Environmental Satellite (GOES) satellites. Here, we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time, which were observed by the GOES satellite at night. Similar to the 100-300-keV precipitated-electron behavior, the low energy 30-100-keV electron precipitation is primarily located east of the transmitter. However, the latter does not drift eastward to the same extent as the former, possibly because of the lower electron velocity. The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range, in contrast to the 100-300-keV electrons which are at L = 1.67-1.9. This is consistent with the perspective that the energy of the VLF-wave-induced electron flux enhancement decreases with higher L-shell values. We expand upon the rationality of the simultaneous enhancement of the 30-100- and 100-300-keV electron fluxes through comparison with the cyclotron resonance theory for the quasi-linear wave-particle interaction. In addition, we interpret the asymmetry characteristics of NWC electric power distribution in north and south hemisphere by ray tracing model. Finally, we present considerable discussion and show that good agreement exists between the observation of satellites and theory. Supported by the China Seismo-Electromagnetic Satellite Mission Ground-Based Verification Project of the Administration of Science, Technology, and Industry for National Defense and Asia-Pacific Space Cooperation Organization Project (APSCO-SP/PM-EARTHQUAKE).

  16. Electron currents in field reversed mirror dynamics: Theory and hybrid simulation

    International Nuclear Information System (INIS)

    Stark, R.A.

    1987-01-01

    To model the dynamics of the Field-Reversed Mirror (FRM) as a whole we have developed a 1-D radical hybrid code which also incorporates the above electron null current model. This code, named FROST, models the plasma as azimuthally symmetric with no axial dependence. A multi-group method in energy and canonical angular momentum describes the large-orbit ions from the beam. Massless fluid equations describe electrons and low energy ions. Since a fluid treatment for electrons is invalid near a field null, the null region electron current model discussed above has been included for this region, a unique feature. Results of simulation of neutral beam start-up in a 2XIIB-like plasma is discussed. There FROST predicts that electron currents will retard, but not prevent reversal of the magnetic field at the plasma center. These results are optimistic when compared to actual reversal experiments in 2XIIB, because there finite axial length effects and micro-instabilities substantially deteriorated the ion confinement. Nevertheless, because of the importance of the electron current in a low field region in the FRM, FROST represents a valuable intermediate step toward a more complete description of FRM dynamics. 54 refs., 50 figs., 3 tabs

  17. Xyce Parallel Electronic Simulator - User's Guide, Version 1.0

    Energy Technology Data Exchange (ETDEWEB)

    HUTCHINSON, SCOTT A; KEITER, ERIC R.; HOEKSTRA, ROBERT J.; WATERS, LON J.; RUSSO, THOMAS V.; RANKIN, ERIC LAMONT; WIX, STEVEN D.

    2002-11-01

    This manual describes the use of the Xyce Parallel Electronic Simulator code for simulating electrical circuits at a variety of abstraction levels. The Xyce Parallel Electronic Simulator has been written to support,in a rigorous manner, the simulation needs of the Sandia National Laboratories electrical designers. As such, the development has focused on improving the capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers. (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) A client-server or multi-tiered operating model wherein the numerical kernel can operate independently of the graphical user interface (GUI). (4) Object-oriented code design and implementation using modern coding-practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. The code is a parallel code in the most general sense of the phrase--a message passing parallel implementation--which allows it to run efficiently on the widest possible number of computing platforms. These include serial, shared-memory and distributed-memory parallel as well as heterogeneous platforms. Furthermore, careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved even as the number of processors grows. Another feature required by designers is the ability to add device models, many specific to the needs of Sandia, to the code. To this end, the device package in the Xyce Parallel Electronic Simulator is designed to support a variety of device model inputs. These input formats include standard analytical models, behavioral models

  18. Electronic Payments Profitability Extent Model

    Directory of Open Access Journals (Sweden)

    Rudolf Vohnout

    2016-12-01

    Full Text Available Cashless payments are recent phenomena, which even increased with the introduction of contactless means like NFC, PayPass or payWave. Such new methods speed-up the entire payment process and in comparison to cash transactions are much simpler and faster. But on the other hand the key question for merchant is if it is worth to have such device, which accept these new payment means or not to have the terminal at all. What is the amount of cash flow, which delimits the cash holdings to be still profitable? This paper tries to give answers to such question by presenting general profitability model, which will address defining the cash threshold amount. The aim is to show that cash holdings could be profitable up to certain amount, but after the threshold is met, cashless payment methods are fairly superior despite their additional costs.

  19. Bragg's Law diffraction simulations for electron backscatter diffraction analysis

    International Nuclear Information System (INIS)

    Kacher, Josh; Landon, Colin; Adams, Brent L.; Fullwood, David

    2009-01-01

    In 2006, Angus Wilkinson introduced a cross-correlation-based electron backscatter diffraction (EBSD) texture analysis system capable of measuring lattice rotations and elastic strains to high resolution. A variation of the cross-correlation method is introduced using Bragg's Law-based simulated EBSD patterns as strain free reference patterns that facilitates the use of the cross-correlation method with polycrystalline materials. The lattice state is found by comparing simulated patterns to collected patterns at a number of regions on the pattern using the cross-correlation function and calculating the deformation from the measured shifts of each region. A new pattern can be simulated at the deformed state, and the process can be iterated a number of times to converge on the absolute lattice state. By analyzing an iteratively rotated single crystal silicon sample and recovering the rotation, this method is shown to have an angular resolution of ∼0.04 o and an elastic strain resolution of ∼7e-4. As an example of applications, elastic strain and curvature measurements are used to estimate the dislocation density in a single grain of a compressed polycrystalline Mg-based AZ91 alloy.

  20. PGOPHER: A program for simulating rotational, vibrational and electronic spectra

    Science.gov (United States)

    Western, Colin M.

    2017-01-01

    The PGOPHER program is a general purpose program for simulating and fitting molecular spectra, particularly the rotational structure. The current version can handle linear molecules, symmetric tops and asymmetric tops and many possible transitions, both allowed and forbidden, including multiphoton and Raman spectra in addition to the common electric dipole absorptions. Many different interactions can be included in the calculation, including those arising from electron and nuclear spin, and external electric and magnetic fields. Multiple states and interactions between them can also be accounted for, limited only by available memory. Fitting of experimental data can be to line positions (in many common formats), intensities or band contours and the parameters determined can be level populations as well as rotational constants. PGOPHER is provided with a powerful and flexible graphical user interface to simplify many of the tasks required in simulating, understanding and fitting molecular spectra, including Fortrat diagrams and energy level plots in addition to overlaying experimental and simulated spectra. The program is open source, and can be compiled with open source tools. This paper provides a formal description of the operation of version 9.1.

  1. Hybrid model for simulation of plasma jet injection in tokamak

    Science.gov (United States)

    Galkin, Sergei A.; Bogatu, I. N.

    2016-10-01

    Hybrid kinetic model of plasma treats the ions as kinetic particles and the electrons as charge neutralizing massless fluid. The model is essentially applicable when most of the energy is concentrated in the ions rather than in the electrons, i.e. it is well suited for the high-density hyper-velocity C60 plasma jet. The hybrid model separates the slower ion time scale from the faster electron time scale, which becomes disregardable. That is why hybrid codes consistently outperform the traditional PIC codes in computational efficiency, still resolving kinetic ions effects. We discuss 2D hybrid model and code with exact energy conservation numerical algorithm and present some results of its application to simulation of C60 plasma jet penetration through tokamak-like magnetic barrier. We also examine the 3D model/code extension and its possible applications to tokamak and ionospheric plasmas. The work is supported in part by US DOE DE-SC0015776 Grant.

  2. Modeling and Simulation of Low Voltage Arcs

    NARCIS (Netherlands)

    Ghezzi, L.; Balestrero, A.

    2010-01-01

    Modeling and Simulation of Low Voltage Arcs is an attempt to improve the physical understanding, mathematical modeling and numerical simulation of the electric arcs that are found during current interruptions in low voltage circuit breakers. An empirical description is gained by refined electrical

  3. particle simulation for electrostatic oscillation of virtual cathode in relativistic electron beams

    International Nuclear Information System (INIS)

    Chen Deming; Wang Min

    1990-01-01

    The virtual cathode oscillation in relativistic electron beams is studied by a 1-D electrostatic particle simulation code with finite-size-particle model. When injection current is less than the space charge limiting current, electron beam propagates stably and transsmits completely. When injection current exceeds the space charge limit, its propagation is unstable, a part of electrons reflect and the other electrons transsmit. The position and potential of the virtual cathode caused by space charge effects oscillate periodically. When the beam current increases, the virtual cathode position closer to the injection plane and its oscillating region gets narrower, the virtual cathode potential decreases and its amplitude increases, the oscillation frequency increases above the beam plasma frequency

  4. Simulating electron wave dynamics in graphene superlattices exploiting parallel processing advantages

    Science.gov (United States)

    Rodrigues, Manuel J.; Fernandes, David E.; Silveirinha, Mário G.; Falcão, Gabriel

    2018-01-01

    This work introduces a parallel computing framework to characterize the propagation of electron waves in graphene-based nanostructures. The electron wave dynamics is modeled using both "microscopic" and effective medium formalisms and the numerical solution of the two-dimensional massless Dirac equation is determined using a Finite-Difference Time-Domain scheme. The propagation of electron waves in graphene superlattices with localized scattering centers is studied, and the role of the symmetry of the microscopic potential in the electron velocity is discussed. The computational methodologies target the parallel capabilities of heterogeneous multi-core CPU and multi-GPU environments and are built with the OpenCL parallel programming framework which provides a portable, vendor agnostic and high throughput-performance solution. The proposed heterogeneous multi-GPU implementation achieves speedup ratios up to 75x when compared to multi-thread and multi-core CPU execution, reducing simulation times from several hours to a couple of minutes.

  5. Xyce Parallel Electronic Simulator : users' guide, version 2.0.

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, Robert John; Waters, Lon J.; Rankin, Eric Lamont; Fixel, Deborah A.; Russo, Thomas V.; Keiter, Eric Richard; Hutchinson, Scott Alan; Pawlowski, Roger Patrick; Wix, Steven D.

    2004-06-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator capable of simulating electrical circuits at a variety of abstraction levels. Primarily, Xyce has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability the current state-of-the-art in the following areas: {sm_bullet} Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers. {sm_bullet} Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. {sm_bullet} Device models which are specifically tailored to meet Sandia's needs, including many radiation-aware devices. {sm_bullet} A client-server or multi-tiered operating model wherein the numerical kernel can operate independently of the graphical user interface (GUI). {sm_bullet} Object-oriented code design and implementation using modern coding practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. Xyce is a parallel code in the most general sense of the phrase - a message passing of computing platforms. These include serial, shared-memory and distributed-memory parallel implementation - which allows it to run efficiently on the widest possible number parallel as well as heterogeneous platforms. Careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. One feature required by designers is the ability to add device models, many specific to the needs of Sandia, to the code. To this end, the device package in the Xyce

  6. Conceptual design and simulation investigation of an electronic cooling device powered by hot electrons

    International Nuclear Information System (INIS)

    Su, Guozhen; Zhang, Yanchao; Cai, Ling; Su, Shanhe; Chen, Jincan

    2015-01-01

    Most electronic cooling devices are powered by an external bias applied between the cold and the hot reservoirs. Here we propose a new concept of electronic cooling, in which cooling is achieved by using a reservoir of hot electrons as the power source. The cooling device incorporates two energy filters with the Lorentzian transmission function to respectively select low- and high-energy electrons for transport. Based on the proposed model, we analyze the performances of the device varying with the resonant levels and half widths of two energy filters and establish the optimal configuration of the cooling device. It is believed that such a novel device may be practically used in some nano-energy fields. - Highlights: • A new electronic cooling device powered by hot electrons is proposed. • Two energy filters are employed to select the electrons for transport. • The effects of the resonant levels and half widths of two filters are discussed. • The maximum cooling power and coefficient of performance are calculated. • The optimal configuration of the cooling device is determined.

  7. Teaching Chemistry with Electron Density Models

    Science.gov (United States)

    Shusterman, Gwendolyn P.; Shusterman, Alan J.

    1997-07-01

    Linus Pauling once said that a topic must satisfy two criteria before it can be taught to students. First, students must be able to assimilate the topic within a reasonable amount of time. Second, the topic must be relevant to the educational needs and interests of the students. Unfortunately, the standard general chemistry textbook presentation of "electronic structure theory", set as it is in the language of molecular orbitals, has a difficult time satisfying either criterion. Many of the quantum mechanical aspects of molecular orbitals are too difficult for most beginning students to appreciate, much less master, and the few applications that are presented in the typical textbook are too limited in scope to excite much student interest. This article describes a powerful new method for teaching students about electronic structure and its relevance to chemical phenomena. This method, which we have developed and used for several years in general chemistry (G.P.S.) and organic chemistry (A.J.S.) courses, relies on computer-generated three-dimensional models of electron density distributions, and largely satisfies Pauling's two criteria. Students find electron density models easy to understand and use, and because these models are easily applied to a broad range of topics, they successfully convey to students the importance of electronic structure. In addition, when students finally learn about orbital concepts they are better prepared because they already have a well-developed three-dimensional picture of electronic structure to fall back on. We note in this regard that the types of models we use have found widespread, rigorous application in chemical research (1, 2), so students who understand and use electron density models do not need to "unlearn" anything before progressing to more advanced theories.

  8. Three axis electronic flight motion simulator real time control system design and implementation

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhiyuan; Miao, Zhonghua, E-mail: zhonghua-miao@163.com; Wang, Xiaohua [School of Mechatronic Engineering and Automation, Shanghai University, Shanghai, 200072 (China); Wang, Xuyong [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2014-12-15

    A three axis electronic flight motion simulator is reported in this paper including the modelling, the controller design as well as the hardware implementation. This flight motion simulator could be used for inertial navigation test and high precision inertial navigation system with good dynamic and static performances. A real time control system is designed, several control system implementation problems were solved including time unification with parallel port interrupt, high speed finding-zero method of rotary inductosyn, zero-crossing management with continuous rotary, etc. Tests were carried out to show the effectiveness of the proposed real time control system.

  9. Three axis electronic flight motion simulator real time control system design and implementation.

    Science.gov (United States)

    Gao, Zhiyuan; Miao, Zhonghua; Wang, Xuyong; Wang, Xiaohua

    2014-12-01

    A three axis electronic flight motion simulator is reported in this paper including the modelling, the controller design as well as the hardware implementation. This flight motion simulator could be used for inertial navigation test and high precision inertial navigation system with good dynamic and static performances. A real time control system is designed, several control system implementation problems were solved including time unification with parallel port interrupt, high speed finding-zero method of rotary inductosyn, zero-crossing management with continuous rotary, etc. Tests were carried out to show the effectiveness of the proposed real time control system.

  10. Simulation methods supporting homologation of Electronic Stability Control in vehicle variants

    Science.gov (United States)

    Lutz, Albert; Schick, Bernhard; Holzmann, Henning; Kochem, Michael; Meyer-Tuve, Harald; Lange, Olav; Mao, Yiqin; Tosolin, Guido

    2017-10-01

    Vehicle simulation has a long tradition in the automotive industry as a powerful supplement to physical vehicle testing. In the field of Electronic Stability Control (ESC) system, the simulation process has been well established to support the ESC development and application by suppliers and Original Equipment Manufacturers (OEMs). The latest regulation of the United Nations Economic Commission for Europe UN/ECE-R 13 allows also for simulation-based homologation. This extends the usage of simulation from ESC development to homologation. This paper gives an overview of simulation methods, as well as processes and tools used for the homologation of ESC in vehicle variants. The paper first describes the generic homologation process according to the European Regulation (UN/ECE-R 13H, UN/ECE-R 13/11) and U.S. Federal Motor Vehicle Safety Standard (FMVSS 126). Subsequently the ESC system is explained as well as the generic application and release process at the supplier and OEM side. Coming up with the simulation methods, the ESC development and application process needs to be adapted for the virtual vehicles. The simulation environment, consisting of vehicle model, ESC model and simulation platform, is explained in detail with some exemplary use-cases. In the final section, examples of simulation-based ESC homologation in vehicle variants are shown for passenger cars, light trucks, heavy trucks and trailers. This paper is targeted to give a state-of-the-art account of the simulation methods supporting the homologation of ESC systems in vehicle variants. However, the described approach and the lessons learned can be used as reference in future for an extended usage of simulation-supported releases of the ESC system up to the development and release of driver assistance systems.

  11. PIC simulations of the trapped electron filamentation instability in finite-width electron plasma waves

    Science.gov (United States)

    Winjum, B. J.; Banks, J. W.; Berger, R. L.; Cohen, B. I.; Chapman, T.; Hittinger, J. A. F.; Rozmus, W.; Strozzi, D. J.; Brunner, S.

    2012-10-01

    We present results on the kinetic filamentation of finite-width nonlinear electron plasma waves (EPW). Using 2D simulations with the PIC code BEPS, we excite a traveling EPW with a Gaussian transverse profile and a wavenumber k0λDe= 1/3. The transverse wavenumber spectrum broadens during transverse EPW localization for small width (but sufficiently large amplitude) waves, while the spectrum narrows to a dominant k as the initial EPW width increases to the plane-wave limit. For large EPW widths, filaments can grow and destroy the wave coherence before transverse localization destroys the wave; the filaments in turn evolve individually as self-focusing EPWs. Additionally, a transverse electric field develops that affects trapped electrons, and a beam-like distribution of untrapped electrons develops between filaments and on the sides of a localizing EPW. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD-061. Supported also under Grants DE-FG52-09NA29552 and NSF-Phy-0904039. Simulations were performed on UCLA's Hoffman2 and NERSC's Hopper.

  12. Tokamak electron heat transport by direct numerical simulation of small scale turbulence

    International Nuclear Information System (INIS)

    Labit, B.

    2002-10-01

    In a fusion machine, understanding plasma turbulence, which causes a degradation of the measured energy confinement time, would constitute a major progress in this field. In tokamaks, the measured ion and electron thermal conductivities are of comparable magnitude. The possible sources of turbulence are the temperature and density gradients occurring in a fusion plasma. Whereas the heat losses in the ion channel are reasonably well understood, the origin of the electron losses is more uncertain. In addition to the radial velocity associated to the fluctuations of the electric field, electrons are more affected than ions by the magnetic field fluctuations. In experiments, the confinement time can be conveniently expressed in terms of dimensionless parameters. Although still somewhat too imprecise, these scaling laws exhibit strong dependencies on the normalized pressure β or the normalized Larmor radius, ρ * . The present thesis assesses whether a tridimensional, electromagnetic, nonlinear fluid model of plasma turbulence driven by a specific instability can reproduce the dependence of the experimental electron heat losses on the dimensionless parameters β and ρ * . The investigated interchange instability is the Electron Temperature Gradient driven one (ETG). The model is built by using the set of Braginskii equations. The developed simulation code is global in the sense that a fixed heat flux is imposed at the inner boundary, leaving the gradients free to evolve. From the nonlinear simulations, we have put in light three characteristics for the ETG turbulence: the turbulent transport is essentially electrostatic; the potential and pressure fluctuations form radially elongated cells called streamers; the transport level is very low compared to the experimental values. The thermal transport dependence study has shown a very small role of the normalized pressure, which is in contradiction with the Ohkama's formula. On the other hand, the crucial role of the

  13. Exact diagonalization library for quantum electron models

    Science.gov (United States)

    Iskakov, Sergei; Danilov, Michael

    2018-04-01

    We present an exact diagonalization C++ template library (EDLib) for solving quantum electron models, including the single-band finite Hubbard cluster and the multi-orbital impurity Anderson model. The observables that can be computed using EDLib are single particle Green's functions and spin-spin correlation functions. This code provides three different types of Hamiltonian matrix storage that can be chosen based on the model.

  14. Real-Time Robust Adaptive Modeling and Scheduling for an Electronic Commerce Server

    Science.gov (United States)

    Du, Bing; Ruan, Chun

    With the increasing importance and pervasiveness of Internet services, it is becoming a challenge for the proliferation of electronic commerce services to provide performance guarantees under extreme overload. This paper describes a real-time optimization modeling and scheduling approach for performance guarantee of electronic commerce servers. We show that an electronic commerce server may be simulated as a multi-tank system. A robust adaptive server model is subject to unknown additive load disturbances and uncertain model matching. Overload control techniques are based on adaptive admission control to achieve timing guarantees. We evaluate the performance of the model using a complex simulation that is subjected to varying model parameters and massive overload.

  15. Numerical Simulations of X-Ray Free Electron Lasers (XFEL)

    KAUST Repository

    Antonelli, Paolo

    2014-11-04

    We study a nonlinear Schrödinger equation which arises as an effective single particle model in X-ray free electron lasers (XFEL). This equation appears as a first principles model for the beam-matter interactions that would take place in an XFEL molecular imaging experiment in [A. Fratalocchi and G. Ruocco, Phys. Rev. Lett., 106 (2011), 105504]. Since XFEL are more powerful by several orders of magnitude than more conventional lasers, the systematic investigation of many of the standard assumptions and approximations has attracted increased attention. In this model the electrons move under a rapidly oscillating electromagnetic field, and the convergence of the problem to an effective time-averaged one is examined. We use an operator splitting pseudospectral method to investigate numerically the behavior of the model versus that of its time-averaged version in complex situations, namely the energy subcritical/mass supercritical case and in the presence of a periodic lattice. We find the time-averaged model to be an effective approximation, even close to blowup, for fast enough oscillations of the external field. This work extends previous analytical results for simpler cases [P. Antonelli, A. Athanassoulis, H. Hajaiej, and P. Markowich, Arch. Ration. Mech. Anal., 211 (2014), pp. 711--732].

  16. Monte Carlo simulation of heavy ion induced kinetic electron emission from an Al surface

    CERN Document Server

    Ohya, K

    2002-01-01

    A Monte Carlo simulation is performed in order to study heavy ion induced kinetic electron emission from an Al surface. In the simulation, excitation of conduction band electrons by the projectile ion and recoiling target atoms is treated on the basis of the partial wave expansion method, and the cascade multiplication process of the excited electrons is simulated as well as collision cascade of the recoiling target atoms. Experimental electron yields near conventional threshold energies of heavy ions are simulated by an assumption of a lowering in the apparent surface barrier for the electrons. The present calculation derives components for electron excitations by the projectile ion, the recoiling target atoms and the electron cascades, from the calculated total electron yield. The component from the recoiling target atoms increases with increasing projectile mass, whereas the component from the electron cascade decreases. Although the components from the projectile ion and the electron cascade increase with...

  17. Simulation of electron beam formation and transport in a gas-filled electron-optical system with a plasma emitter

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, A. A. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation); Kornilov, S. Yu., E-mail: kornilovsy@gmail.com; Rempe, N. G. [Tomsk State University of Control Systems and Radioelectronics (Russian Federation); Shidlovskiy, S. V. [Tomsk State University (Russian Federation); Shklyaev, V. A. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation)

    2016-07-15

    The results of computer simulations of the electron-optical system of an electron gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the electron beam formation and transport. The electron trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and transport are described. Recommendations for optimizing the electron-optical system with a plasma emitter are presented.

  18. Whole-building Hygrothermal Simulation Model

    DEFF Research Database (Denmark)

    Rode, Carsten; Grau, Karl

    2003-01-01

    An existing integrated simulation tool for dynamic thermal simulation of building was extended with a transient model for moisture release and uptake in building materials. Validation of the new model was begun with comparison against measurements in an outdoor test cell furnished with single...... materials. Almost quasi-steady, cyclic experiments were used to compare the indoor humidity variation and the numerical results of the integrated simulation tool with the new moisture model. Except for the case with chipboard as furnishing, the predictions of indoor humidity with the detailed model were...

  19. Final Report for 'ParSEC-Parallel Simulation of Electron Cooling''

    International Nuclear Information System (INIS)

    David L Bruhwiler

    2005-01-01

    parameters but with different ''seeds'' for the particle loading. VORPAL can now be used to simulate other electron cooling facilities around the world, and it is also suitable for other accelerator modeling applications of direct interest to the Department of Energy. For example: (a) the Boersch effect in transport of strongly-magnetized electron beams for electron cooling sections, (b) the intrabeam scattering (IBS) effect in heavy ion accelerators, (c) the formation of crystalline beams and (d) target physics for heavy-ion fusion (HIF)

  20. Test of models for electron transport in laser produced plasmas

    International Nuclear Information System (INIS)

    Colombant, D.G.; Manheimer, W.M.; Busquet, M.

    2005-01-01

    This paper examines five different models of electron thermal transport in laser produced spherical implosions. These are classical, classical with a flux limit f, delocalization, beam deposition model, and Fokker-Planck solutions. In small targets, the results are strongly dependent on f for flux limit models, with small f's generating very steep temperature gradients. Delocalization models are characterized by large preheat in the center of the target. The beam deposition model agrees reasonably well with the Fokker-Planck simulation results. For large, high gain fusion targets, the delocalization model shows the gain substantially reduced by the preheat. However, flux limitation models show gain largely independent of f, with the beam deposition model also showing the same high gain

  1. Simulation modeling for the health care manager.

    Science.gov (United States)

    Kennedy, Michael H

    2009-01-01

    This article addresses the use of simulation software to solve administrative problems faced by health care managers. Spreadsheet add-ins, process simulation software, and discrete event simulation software are available at a range of costs and complexity. All use the Monte Carlo method to realistically integrate probability distributions into models of the health care environment. Problems typically addressed by health care simulation modeling are facility planning, resource allocation, staffing, patient flow and wait time, routing and transportation, supply chain management, and process improvement.

  2. Protein Simulation Data in the Relational Model.

    Science.gov (United States)

    Simms, Andrew M; Daggett, Valerie

    2012-10-01

    High performance computing is leading to unprecedented volumes of data. Relational databases offer a robust and scalable model for storing and analyzing scientific data. However, these features do not come without a cost-significant design effort is required to build a functional and efficient repository. Modeling protein simulation data in a relational database presents several challenges: the data captured from individual simulations are large, multi-dimensional, and must integrate with both simulation software and external data sites. Here we present the dimensional design and relational implementation of a comprehensive data warehouse for storing and analyzing molecular dynamics simulations using SQL Server.

  3. 2D PIC simulations for an EN discharge with magnetized electrons and unmagnetized ions

    Science.gov (United States)

    Lieberman, Michael A.; Kawamura, Emi; Lichtenberg, Allan J.

    2009-10-01

    We conducted 2D particle-in-cell (PIC) simulations for an electronegative (EN) discharge with magnetized electrons and unmagnetized ions, and compared the results to a previously developed 1D (radial) analytical model of an EN plasma with strongly magnetized electrons and weakly magnetized ions [1]. In both cases, there is a static uniform applied magnetic field in the axial direction. The 1D radial model mimics the wall losses of the particles in the axial direction by introducing a bulk loss frequency term νL. A special (desired) solution was found in which only positive and negative ions but no electrons escaped radially. The 2D PIC results show good agreement with the 1D model over a range of parameters and indicate that the analytical form of νL employed in [1] is reasonably accurate. However, for the PIC simulations, there is always a finite flux of electrons to the radial wall which is about 10 to 30% of the negative ion flux.[4pt] [1] G. Leray, P. Chabert, A.J. Lichtenberg and M.A. Lieberman, J. Phys. D, accepted for publication 2009.

  4. The Anderson model for electron localisation

    International Nuclear Information System (INIS)

    Pruisken, A.M.M.; Schaefer, L.

    1982-01-01

    The Anderson model for localisation problems is treated with field theory employing the replica trick. We show that no valid perturbation theory results out of the usual (S2)2 formalism due to mishandling of symmetries. The problem is reformulated in terms of matrix fields. It is shown that the Anderson model asymptotically exhibits an exact local gauge symmetry. Elimination of massive longitudinal components leads to a non-compact sigma model, obtained earlier for the description of electronic disorder. We thus establish that the Anderson model is in the same universality class as Wegner's gauge invariant real matrix model. (orig.)

  5. Modeling and simulation of blood collection systems.

    Science.gov (United States)

    Alfonso, Edgar; Xie, Xiaolan; Augusto, Vincent; Garraud, Olivier

    2012-03-01

    This paper addresses the modeling and simulation of blood collection systems in France for both fixed site and mobile blood collection with walk in whole blood donors and scheduled plasma and platelet donors. Petri net models are first proposed to precisely describe different blood collection processes, donor behaviors, their material/human resource requirements and relevant regulations. Petri net models are then enriched with quantitative modeling of donor arrivals, donor behaviors, activity times and resource capacity. Relevant performance indicators are defined. The resulting simulation models can be straightforwardly implemented with any simulation language. Numerical experiments are performed to show how the simulation models can be used to select, for different walk in donor arrival patterns, appropriate human resource planning and donor appointment strategies.

  6. 1D numerical simulation of charge trapping in an insulator submitted to an electron beam irradiation. Part I: Computation of the initial secondary electron emission yield

    International Nuclear Information System (INIS)

    Aoufi, A.; Damamme, G.

    2011-01-01

    The aim of this work is to study by numerical simulation a mathematical modelling technique describing charge trapping during initial charge injection in an insulator submitted to electron beam irradiation. A two-fluxes method described by a set of two stationary transport equations is used to split the electron current j e (z) into coupled forward j e+ (z) and backward j e (z) currents and such that j e (z) = j e+ (z) - j e- (z). The sparse algebraic linear system, resulting from the vertex-centered finite-volume discretization scheme is solved by an iterative decoupled fixed point method which involves the direct inversion of a bi-diagonal matrix. The sensitivity of the initial secondary electron emission yield with respect to the energy of incident primary electrons beam, that is penetration depth of the incident beam, or electron cross sections (absorption and diffusion) is investigated by numerical simulations. (authors)

  7. Modeling and Simulation of Matrix Converter

    DEFF Research Database (Denmark)

    Liu, Fu-rong; Klumpner, Christian; Blaabjerg, Frede

    2005-01-01

    This paper discusses the modeling and simulation of matrix converter. Two models of matrix converter are presented: one is based on indirect space vector modulation and the other is based on power balance equation. The basis of these two models is• given and the process on modeling is introduced...

  8. Three-dimensional simulations of an XUV free-electron laser

    International Nuclear Information System (INIS)

    Goldstein, J.C.; McVey, B.D.; Newnam, B.E.

    1985-01-01

    Operation of free-electron lasers (FEL) at long optical wavelengths (greater than or equal to 600 nm) has now been successfully demonstrated at several laboratories. To operate an FEL at shorter wavelengths imposes constraints on the brightness of the electron beam which are difficult to achieve. Until recently, it was perceived that only an electron storage ring could satisfy these beam requirements. However, our previous 1-D theoretical calculations revealed that modest improvements in the emittance available from rf-linear accelerators would be sufficient to allow operation of an FEL in the XUV spectral range (greater than or equal to 50 nm). We shall present new theoretical results for the design of a linac-driven XUV FEL derived from an improved simulation model. The model is fully three-dimensional in its treatment of the undulator magnetic field, the optical radiation field, and the motion of electrons in a finite-emittance beam. Furthermore, the model computes self-consistently the motion of the electrons and the amplification, diffraction, and the refraction of the light within the undulator magnet. Propagation of the optical beam and reflection at the mirrors of the optical resonator are incorporated in the model so that a complete laser oscillator solution can be generated. The computed performance parameters of a particular XUV FEL oscillator design will be compared with the output of synchrotron radiation sources. 26 refs., 8 figs

  9. Electron beam treatment of simulated marine diesel exhaust gases

    Directory of Open Access Journals (Sweden)

    Licki Janusz

    2015-09-01

    Full Text Available The exhaust gases from marine diesel engines contain high SO2 and NOx concentration. The applicability of the electron beam flue gas treatment technology for purification of marine diesel exhaust gases containing high SO2 and NOx concentration gases was the main goal of this paper. The study was performed in the laboratory plant with NOx concentration up to 1700 ppmv and SO2 concentration up to 1000 ppmv. Such high NOx and SO2 concentrations were observed in the exhaust gases from marine high-power diesel engines fuelled with different heavy fuel oils. In the first part of study the simulated exhaust gases were irradiated by the electron beam from accelerator. The simultaneous removal of SO2 and NOx were obtained and their removal efficiencies strongly depend on irradiation dose and inlet NOx concentration. For NOx concentrations above 800 ppmv low removal efficiencies were obtained even if applied high doses. In the second part of study the irradiated gases were directed to the seawater scrubber for further purification. The scrubbing process enhances removal efficiencies of both pollutants. The SO2 removal efficiencies above 98.5% were obtained with irradiation dose greater than 5.3 kGy. For inlet NOx concentrations of 1700 ppmv the NOx removal efficiency about 51% was obtained with dose greater than 8.8 kGy. Methods for further increase of NOx removal efficiency are presented in the paper.

  10. Simulation studies of plasma waves in the electron foreshock: The transition from reactive to kinetic instability

    International Nuclear Information System (INIS)

    Dum, C.T.

    1990-01-01

    The electron beam-plasma instability is analyzed in particle simulation experiments, starting with a beam of small velocity spread. The dispersion relation is solved for snapshots of the actual evolving electron distribution function, rather than for the usual models consisting of Maxwellians. As the beam broadens, the analysis shows a transition from reactive beam modes, with frequencies extending much below the plasma frequency ω e , to kinetic instability of Langmuir waves, ω∼ω e , which is in agreement with the frequencies and growth rates observed in the simulation. Beam evolution is also in agreement with quasi-linear theory, except at the end of the reactive phase when trapping of beam electrons is seen. Although the spectrum temporarily narrows at this stage, there are, in contrast to previous simulations, still many modes present. the system then can proceed to a kinetic phase in which quasi-linear theory is again applicable. This stage is identical with the evolution starting from a gentle broad beam, except that wave levels are several times higher. With higher wave levels, mode coupling effects are also more prominent, but are still unable to prevent plateau formation. In contrast to the Langmuir wave regime, the reactive broadband wave regime lasts only for a relatively short period. In the electron foreshock it could only persist if a narrow beam or a sharp cutoff feature were maintained by continued beam injection and the time-of-flight mechanism

  11. Non-linear gyrokinetic simulations of microturbulence in TCV electron internal transport barriers

    Energy Technology Data Exchange (ETDEWEB)

    Lapillonne, X; Brunner, S; Sauter, O; Villard, L [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Fable, E; Goerler, T; Jenko, F; Merz, F, E-mail: stephan.brunner@epfl.ch [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2011-05-15

    Using the local (flux-tube) version of the Eulerian code GENE (Jenko et al 2000 Phys. Plasmas 7 1904), gyrokinetic simulations of microturbulence were carried out considering parameters relevant to electron-internal transport barriers (e-ITBs) in the TCV tokamak (Sauter et al 2005 Phys. Rev. Lett. 94 105002), generated under conditions of low or negative shear. For typical density and temperature gradients measured in such barriers, the corresponding simulated fluctuation spectra appears to simultaneously contain longer wavelength trapped electron modes (TEMs, for typically k{sub p}erpendicular{rho}{sub i} < 0.5, k{sub p}erpendicular being the characteristic perpendicular wavenumber and {rho}{sub i} the ion Larmor radius) and shorter wavelength ion temperature gradient modes (ITG, k{sub p}erpendicular{rho}{sub i} > 0.5). The contributions to the electron particle flux from these two types of modes are, respectively, outward/inward and may cancel each other for experimentally realistic gradients. This mechanism may partly explain the feasibility of e-ITBs. The non-linear simulation results confirm the predictions of a previously developed quasi-linear model (Fable et al 2010 Plasma Phys. Control. Fusion 52 015007), namely that the stationary condition of zero particle flux is obtained through the competitive contributions of ITG and TEM. A quantitative comparison of the electron heat flux with experimental estimates is presented as well.

  12. Non-linear gyrokinetic simulations of microturbulence in TCV electron internal transport barriers

    Science.gov (United States)

    Lapillonne, X.; Brunner, S.; Sauter, O.; Villard, L.; Fable, E.; Görler, T.; Jenko, F.; Merz, F.

    2011-05-01

    Using the local (flux-tube) version of the Eulerian code GENE (Jenko et al 2000 Phys. Plasmas 7 1904), gyrokinetic simulations of microturbulence were carried out considering parameters relevant to electron-internal transport barriers (e-ITBs) in the TCV tokamak (Sauter et al 2005 Phys. Rev. Lett. 94 105002), generated under conditions of low or negative shear. For typical density and temperature gradients measured in such barriers, the corresponding simulated fluctuation spectra appears to simultaneously contain longer wavelength trapped electron modes (TEMs, for typically k⊥ρi 0.5). The contributions to the electron particle flux from these two types of modes are, respectively, outward/inward and may cancel each other for experimentally realistic gradients. This mechanism may partly explain the feasibility of e-ITBs. The non-linear simulation results confirm the predictions of a previously developed quasi-linear model (Fable et al 2010 Plasma Phys. Control. Fusion 52 015007), namely that the stationary condition of zero particle flux is obtained through the competitive contributions of ITG and TEM. A quantitative comparison of the electron heat flux with experimental estimates is presented as well.

  13. EGS4, Electron Photon Shower Simulation by Monte-Carlo

    International Nuclear Information System (INIS)

    1998-01-01

    1 - Description of program or function: The EGS code system is one of a chain of three codes designed to solve the electromagnetic shower problem by Monte Carlo simulation. This chain makes possible simulation of almost any electron-photon transport problem conceivable. The structure of the system, with its global features, modular form, and structured programming, is readily adaptable to virtually any interfacing scheme that is desired on the part of the user. EGS4 is a package of subroutines plus block data with a flexible user interface. This allows for greater flexibility without requiring the user to be overly familiar with the internal details of the code. Combining this with the macro facility capabilities of the Mortran3 language, this reduces the likelihood that user edits will introduce bugs into the code. EGS4 uses material cross section and branching ratio data created and fit by the companion code, PEGS4. EGS4 allows for the implementation of importance sampling and other variance reduction techniques such as leading particle biasing, splitting, path length biasing, Russian roulette, etc. 2 - Method of solution: EGS employs the Monte Carlo method of solution. It allows all of the fundamental processes to be included and arbitrary geometries can be treated, also. Other minor processes, such as photoneutron production, can be added as a further generalization. Since showers develop randomly according to the quantum laws of probability, each shower is different. We again are led to the Monte Carlo method. 3 - Restrictions on the complexity of the problem: None noted

  14. Simulation models for tokamak plasmas

    International Nuclear Information System (INIS)

    Dimits, A.M.; Cohen, B.I.

    1992-01-01

    Two developments in the nonlinear simulation of tokamak plasmas are described: (A) Simulation algorithms that use quasiballooning coordinates have been implemented in a 3D fluid code and a 3D partially linearized (Δf) particle code. In quasiballooning coordinates, one of the coordinate directions is closely aligned with that of the magnetic field, allowing both optimal use of the grid resolution for structures highly elongated along the magnetic field as well as implementation of the correct periodicity conditions with no discontinuities in the toroidal direction. (B) Progress on the implementation of a likeparticle collision operator suitable for use in partially linearized particle codes is reported. The binary collision approach is shown to be unusable for this purpose. The algorithm under development is a complete version of the test-particle plus source-field approach that was suggested and partially implemented by Xu and Rosenbluth

  15. Computer modeling and simulation in inertial confinement fusion

    International Nuclear Information System (INIS)

    McCrory, R.L.; Verdon, C.P.

    1989-03-01

    The complex hydrodynamic and transport processes associated with the implosion of an inertial confinement fusion (ICF) pellet place considerable demands on numerical simulation programs. Processes associated with implosion can usually be described using relatively simple models, but their complex interplay requires that programs model most of the relevant physical phenomena accurately. Most hydrodynamic codes used in ICF incorporate a one-fluid, two-temperature model. Electrons and ions are assumed to flow as one fluid (no charge separation). Due to the relatively weak coupling between the ions and electrons, each species is treated separately in terms of its temperature. In this paper we describe some of the major components associated with an ICF hydrodynamics simulation code. To serve as an example we draw heavily on a two-dimensional Lagrangian hydrodynamic code (ORCHID) written at the University of Rochester's Laboratory for Laser Energetics. 46 refs., 19 figs., 1 tab

  16. Variable slip wind generator modeling for real-time simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gagnon, R.; Brochu, J.; Turmel, G. [Hydro-Quebec, Varennes, PQ (Canada). IREQ

    2006-07-01

    A model of a wind turbine using a variable slip wound-rotor induction machine was presented. The model was created as part of a library of generic wind generator models intended for wind integration studies. The stator winding of the wind generator was connected directly to the grid and the rotor was driven by the turbine through a drive train. The variable resistors was synthesized by an external resistor in parallel with a diode rectifier. A forced-commutated power electronic device (IGBT) was connected to the wound rotor by slip rings and brushes. Simulations were conducted in a Matlab/Simulink environment using SimPowerSystems blocks to model power systems elements and Simulink blocks to model the turbine, control system and drive train. Detailed descriptions of the turbine, the drive train and the control system were provided. The model's implementation in the simulator was also described. A case study demonstrating the real-time simulation of a wind generator connected at the distribution level of a power system was presented. Results of the case study were then compared with results obtained from the SimPowerSystems off-line simulation. Results showed good agreement between the waveforms, demonstrating the conformity of the real-time and the off-line simulations. The capability of Hypersim for real-time simulation of wind turbines with power electronic converters in a distribution network was demonstrated. It was concluded that hardware-in-the-loop (HIL) simulation of wind turbine controllers for wind integration studies in power systems is now feasible. 5 refs., 1 tab., 6 figs.

  17. A model management system for combat simulation

    OpenAIRE

    Dolk, Daniel R.

    1986-01-01

    The design and implementation of a model management system to support combat modeling is discussed. Structured modeling is introduced as a formalism for representing mathematical models. A relational information resource dictionary system is developed which can accommodate structured models. An implementation is described. Structured modeling is then compared to Jackson System Development (JSD) as a methodology for facilitating discrete event simulation. JSD is currently better at representin...

  18. HVDC System Characteristics and Simulation Models

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S.I.; Han, B.M.; Jang, G.S. [Electric Enginnering and Science Research Institute, Seoul (Korea)

    2001-07-01

    This report deals with the AC-DC power system simulation method by PSS/E and EUROSTAG for the development of a strategy for the reliable operation of the Cheju-Haenam interconnected system. The simulation using both programs is performed to analyze HVDC simulation models. In addition, the control characteristics of the Cheju-Haenam HVDC system as well as Cheju AC system characteristics are described in this work. (author). 104 figs., 8 tabs.

  19. Physically realistic modeling of maritime training simulation

    OpenAIRE

    Cieutat , Jean-Marc

    2003-01-01

    Maritime training simulation is an important matter of maritime teaching, which requires a lot of scientific and technical skills.In this framework, where the real time constraint has to be maintained, all physical phenomena cannot be studied; the most visual physical phenomena relating to the natural elements and the ship behaviour are reproduced only. Our swell model, based on a surface wave simulation approach, permits to simulate the shape and the propagation of a regular train of waves f...

  20. Software-Engineering Process Simulation (SEPS) model

    Science.gov (United States)

    Lin, C. Y.; Abdel-Hamid, T.; Sherif, J. S.

    1992-01-01

    The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments.

  1. Systematic modelling and simulation of refrigeration systems

    DEFF Research Database (Denmark)

    Rasmussen, Bjarne D.; Jakobsen, Arne

    1998-01-01

    The task of developing a simulation model of a refrigeration system can be very difficult and time consuming. In order for this process to be effective, a systematic method for developing the system model is required. This method should aim at guiding the developer to clarify the purpose...... of the simulation, to select appropriate component models and to set up the equations in a well-arranged way. In this paper the outline of such a method is proposed and examples showing the use of this method for simulation of refrigeration systems are given....

  2. Modeling and multidimensional optimization of a tapered free electron laser

    Directory of Open Access Journals (Sweden)

    Y. Jiao

    2012-05-01

    Full Text Available Energy extraction efficiency of a free electron laser (FEL can be greatly increased using a tapered undulator and self-seeding. However, the extraction rate is limited by various effects that eventually lead to saturation of the peak intensity and power. To better understand these effects, we develop a model extending the Kroll-Morton-Rosenbluth, one-dimensional theory to include the physics of diffraction, optical guiding, and radially resolved particle trapping. The predictions of the model agree well with that of the GENESIS single-frequency numerical simulations. In particular, we discuss the evolution of the electron-radiation interaction along the tapered undulator and show that the decreasing of refractive guiding is the major cause of the efficiency reduction, particle detrapping, and then saturation of the radiation power. With this understanding, we develop a multidimensional optimization scheme based on GENESIS simulations to increase the energy extraction efficiency via an improved taper profile and variation in electron beam radius. We present optimization results for hard x-ray tapered FELs, and the dependence of the maximum extractable radiation power on various parameters of the initial electron beam, radiation field, and the undulator system. We also study the effect of the sideband growth in a tapered FEL. Such growth induces increased particle detrapping and thus decreased refractive guiding that together strongly limit the overall energy extraction efficiency.

  3. Simulation of the scattering in a thorium foil of 0.15-2.3 MeV electrons and positrons

    International Nuclear Information System (INIS)

    Bargholtz, Chr.; Holmberg, L.; Liljequist, D.; Tegner, P.E.

    1993-01-01

    Studies of the scattering in thorium of electrons emitted in the decay of 90 Sr, involving measurements of the coincidence spectra of electrons and positrons in the energy region 210-420 keV in search for anomalies, have previously been reported. In the analysis of the experimental results, computer simulations of the scattering and energy loss of the electrons and positrons were used. The present report describes the models and assumptions used in this simulation and the comparison with experimentally determined spectra

  4. Simulation of diode electron source of PSTA latex EBM using OPERA-3D software

    International Nuclear Information System (INIS)

    Taufik; Darsono

    2014-01-01

    Electron beam transport from E-gun to the atmospheres in EBM is determined by main parameters of beam transports such as E-gun, accelerator tube, beam optics (focusing and scanning magnets). In principle the beam transport will optimum if the electron beam travels in axial axes of accelerator tubes, and the beam optics works properly. The EBM E-gun structure of PSTA uses diode type with Pierce cathode where beam transport yield will be affected by electrode voltage of the accelerator tube. To answer above hypothesis the E-gun and accelerator tube will be simulated by making a model used accelerator software programme which is called OPERA-3D. Beam transport parameters, such as distance between cathode and anode of E-gun, accelerator electrode HV, and the symmetry of cathode Pierce E-gun with anode electrode of accelerator tube, will be investigated their impacts to direction and shape of beam transports. The simulation results shows that the three parameters affects to the direction and shape of the beam transport. Diode type of electron gun cannot result parallel electron beam, but the best beam transport of this type electron gun are obtained at the accelerator voltage 300 kV, and the distance between cathode and anode of E-gun 6.1 mm where they are in the symmetry condition. (author)

  5. Electron scattering in the interacting boson model

    International Nuclear Information System (INIS)

    Dieperink, A.E.L.; Iachello, F.; Creswell, C.

    1978-01-01

    It is suggested that the interacting boson model be used in the analysis of electron scattering data. Qualitative features of the expected behavior of the inelastic excitation of some 2 + states in the transitional Sm-Nd region are discussed. (Auth.)

  6. Electron Correlation Models for Optical Activity

    DEFF Research Database (Denmark)

    Höhn, E. G.; O. E. Weigang, Jr.

    1968-01-01

    A two-system no-overlap model for rotatory strength is developed for electric-dipole forbidden as well as allowed transitions. General equations which allow for full utilization of symmetry in the chromophore and in the environment are obtained. The electron correlation terms are developed in full...

  7. Vlasov simulations of electron hole dynamics in inhomogeneous magnetic field

    Science.gov (United States)

    Kuzichev, Ilya; Vasko, Ivan; Agapitov, Oleksiy; Mozer, Forrest; Artemyev, Anton

    2017-04-01

    Electron holes (EHs) or phase space vortices are solitary electrostatic waves existing due to electrons trapped within EH electrostatic potential. Since the first direct observation [1], EHs have been widely observed in the Earth's magnetosphere: in reconnecting current sheets [2], injection fronts [3], auroral region [4], and many other space plasma systems. EHs have typical spatial scales up to tens of Debye lengths, electric field amplitudes up to hundreds of mV/m and propagate along magnetic field lines with velocities of about electron thermal velocity [5]. The role of EHs in energy dissipation and supporting of large-scale potential drops is under active investigation. The accurate interpretation of spacecraft observations requires understanding of EH evolution in inhomogeneous plasma. The critical role of plasma density gradients in EH evolution was demonstrated in [6] using PIC simulations. Interestingly, up to date no studies have addressed a role of magnetic field gradients in EH evolution. In this report, we use 1.5D gyrokinetic Vlasov code to demonstrate the critical role of magnetic field gradients in EH dynamics. We show that EHs propagating into stronger (weaker) magnetic field are decelerated (accelerated) with deceleration (acceleration) rate dependent on the magnetic field gradient. Remarkably, the reflection points of decelerating EHs are independent of the average magnetic field gradient in the system and depend only on the EH parameters. EHs are decelerated (accelerated) faster than would follow from the "quasi-particle" concept assuming that EH is decelerated (accelerated) entirely due to the mirror force acting on electrons trapped within EH. We demonstrate that EH propagation in inhomogeneous magnetic fields results in development of a net potential drop along an EH, which depends on the magnetic field gradient. The revealed features will be helpful for interpreting spacecraft observations and results of advanced particle simulations. In

  8. Deriving simulators for hybrid Chi models

    NARCIS (Netherlands)

    Beek, van D.A.; Man, K.L.; Reniers, M.A.; Rooda, J.E.; Schiffelers, R.R.H.

    2006-01-01

    The hybrid Chi language is formalism for modeling, simulation and verification of hybrid systems. The formal semantics of hybrid Chi allows the definition of provably correct implementations for simulation, verification and realtime control. This paper discusses the principles of deriving an

  9. Modeling and simulation for RF system design

    CERN Document Server

    Frevert, Ronny; Jancke, Roland; Knöchel, Uwe; Schwarz, Peter; Kakerow, Ralf; Darianian, Mohsen

    2005-01-01

    Focusing on RF specific modeling and simulation methods, and system and circuit level descriptions, this work contains application-oriented training material. Accompanied by a CD- ROM, it combines the presentation of a mixed-signal design flow, an introduction into VHDL-AMS and Verilog-A, and the application of commercially available simulators.

  10. Magnetosphere Modeling: From Cartoons to Simulations

    Science.gov (United States)

    Gombosi, T. I.

    2017-12-01

    Over the last half a century physics-based global computer simulations became a bridge between experiment and basic theory and now it represents the "third pillar" of geospace research. Today, many of our scientific publications utilize large-scale simulations to interpret observations, test new ideas, plan campaigns, or design new instruments. Realistic simulations of the complex Sun-Earth system have been made possible by the dramatically increased power of both computing hardware and numerical algorithms. Early magnetosphere models were based on simple E&M concepts (like the Chapman-Ferraro cavity) and hydrodynamic analogies (bow shock). At the beginning of the space age current system models were developed culminating in the sophisticated Tsyganenko-type description of the magnetic configuration. The first 3D MHD simulations of the magnetosphere were published in the early 1980s. A decade later there were several competing global models that were able to reproduce many fundamental properties of the magnetosphere. The leading models included the impact of the ionosphere by using a height-integrated electric potential description. Dynamic coupling of global and regional models started in the early 2000s by integrating a ring current and a global magnetosphere model. It has been recognized for quite some time that plasma kinetic effects play an important role. Presently, global hybrid simulations of the dynamic magnetosphere are expected to be possible on exascale supercomputers, while fully kinetic simulations with realistic mass ratios are still decades away. In the 2010s several groups started to experiment with PIC simulations embedded in large-scale 3D MHD models. Presently this integrated MHD-PIC approach is at the forefront of magnetosphere simulations and this technique is expected to lead to some important advances in our understanding of magnetosheric physics. This talk will review the evolution of magnetosphere modeling from cartoons to current systems

  11. Modeling and simulation of complex systems a framework for efficient agent-based modeling and simulation

    CERN Document Server

    Siegfried, Robert

    2014-01-01

    Robert Siegfried presents a framework for efficient agent-based modeling and simulation of complex systems. He compares different approaches for describing structure and dynamics of agent-based models in detail. Based on this evaluation the author introduces the "General Reference Model for Agent-based Modeling and Simulation" (GRAMS). Furthermore he presents parallel and distributed simulation approaches for execution of agent-based models -from small scale to very large scale. The author shows how agent-based models may be executed by different simulation engines that utilize underlying hard

  12. Development of new generation software tools for simulation of electron beam formation in novel high power gyrotrons

    Science.gov (United States)

    Sabchevski, S.; Zhelyazkov, I.; Benova, E.; Atanassov, V.; Dankov, P.; Thumm, M.; Dammertz, G.; Piosczyk, B.; Illy, S.; Tran, M. Q.; Alberti, S.; Hogge, J.-Ph

    2006-07-01

    Computer aided design (CAD) based on numerical experiments performed by using adequate physical models and efficient simulation codes is an indispensable tool for development, investigation, and optimization of gyrotrons used as radiation sources for electron cyclotron resonance heating (ECRH) of fusion plasmas. In this paper, we review briefly the state-of-the-art in the field of modelling and simulation of intense, relativistic, helical electron beams formed in the electron-optical systems (EOS) of powerful gyrotrons. We discuss both the limitations of the known computer codes and the requirements for increasing their capabilities for solution of various design problems that are being envisaged in the development of the next generation gyrotrons for ECRH. Moreover, we present the concept followed by us in an attempt to unite the advantages of the modern programming techniques with self-consistent, first-principles 3D physical models in the creation of a new highly efficient and versatile software package for simulation of powerful gyrotrons.

  13. A unified mobility model for quantum mechanical simulation of MOSFETs

    International Nuclear Information System (INIS)

    Park, Ji Sun; Lee, Ji Young; Lee, Sang Kyung; Shin, Hyung Soon; Jin, Seong Hoon; Park, Young June; Min, Hong Shik

    2004-01-01

    A unified electron and hole mobility model for inversion and accumulation layers with quantum effect is presented for the first time. By accounting for the screened Coulomb scattering based on the well-known bulk mobility model and allowing the surface roughness scattering term to be a function of net charge, the new model is applicable to the bulk, inversion, and accumulation layers with only one set of fitting parameters. The new model is implemented in the 2-D quantum mechanical device simulator and gives excellent agreement with the experimentally measured effective mobility data over a wide range of effective transverse field, substrate doping, substrate bias, and temperature.

  14. Modeling of the atomic and electronic structures of interfaces

    International Nuclear Information System (INIS)

    Sutton, A.P.

    1988-01-01

    Recent tight binding and Car-Parrinello simulations of grain boundaries in semiconductors are reviewed. A critique is given of some models of embrittlement that are based on electronic structure considerations. The structural unit model of grain boundary structure is critically assessed using some results for mixed tilt and twist grain boundaries. A new method of characterizing interfacial structure in terms of bond angle distribution functions is described. A new formulation of thermodynamic properties of interfaces is presented which focusses on the local atomic environment. Effective, temperature dependent N-body atomic interactions are derived for studying grain boundary structure at elevated temperature

  15. Statistics of excitations in the electron glass model

    Science.gov (United States)

    Palassini, Matteo

    2011-03-01

    We study the statistics of elementary excitations in the classical electron glass model of localized electrons interacting via the unscreened Coulomb interaction in the presence of disorder. We reconsider the long-standing puzzle of the exponential suppression of the single-particle density of states near the Fermi level, by measuring accurately the density of states of charged and electron-hole pair excitations via finite temperature Monte Carlo simulation and zero-temperature relaxation. We also investigate the statistics of large charge rearrangements after a perturbation of the system, which may shed some light on the slow relaxation and glassy phenomena recently observed in a variety of Anderson insulators. In collaboration with Martin Goethe.

  16. NUMERICAL SIMULATION AND MODELING OF UNSTEADY FLOW ...

    African Journals Online (AJOL)

    2014-06-30

    Jun 30, 2014 ... objective of this study is to control the simulation of unsteady flows around structures. ... Aerospace, our results were in good agreement with experimental .... Two-Equation Eddy-Viscosity Turbulence Models for Engineering.

  17. SEIR model simulation for Hepatitis B

    Science.gov (United States)

    Side, Syafruddin; Irwan, Mulbar, Usman; Sanusi, Wahidah

    2017-09-01

    Mathematical modelling and simulation for Hepatitis B discuss in this paper. Population devided by four variables, namely: Susceptible, Exposed, Infected and Recovered (SEIR). Several factors affect the population in this model is vaccination, immigration and emigration that occurred in the population. SEIR Model obtained Ordinary Differential Equation (ODE) non-linear System 4-D which then reduces to 3-D. SEIR model simulation undertaken to predict the number of Hepatitis B cases. The results of the simulation indicates the number of Hepatitis B cases will increase and then decrease for several months. The result of simulation using the number of case in Makassar also found the basic reproduction number less than one, that means, Makassar city is not an endemic area of Hepatitis B.

  18. Maintenance Personnel Performance Simulation (MAPPS) model

    International Nuclear Information System (INIS)

    Siegel, A.I.; Bartter, W.D.; Wolf, J.J.; Knee, H.E.; Haas, P.M.

    1984-01-01

    A stochastic computer model for simulating the actions and behavior of nuclear power plant maintenance personnel is described. The model considers personnel, environmental, and motivational variables to yield predictions of maintenance performance quality and time to perform. The mode has been fully developed and sensitivity tested. Additional evaluation of the model is now taking place

  19. Turbine modelling for real time simulators

    International Nuclear Information System (INIS)

    Oliveira Barroso, A.C. de; Araujo Filho, F. de

    1992-01-01

    A model for vapor turbines and its peripherals has been developed. All the important variables have been included and emphasis has been given for the computational efficiency to obtain a model able to simulate all the modeled equipment. (A.C.A.S.)

  20. Modeling and simulation with operator scaling

    OpenAIRE

    Cohen, Serge; Meerschaert, Mark M.; Rosiński, Jan

    2010-01-01

    Self-similar processes are useful in modeling diverse phenomena that exhibit scaling properties. Operator scaling allows a different scale factor in each coordinate. This paper develops practical methods for modeling and simulating stochastic processes with operator scaling. A simulation method for operator stable Levy processes is developed, based on a series representation, along with a Gaussian approximation of the small jumps. Several examples are given to illustrate practical application...

  1. A model for disruption generated runaway electrons

    International Nuclear Information System (INIS)

    Russo, A.J.; Campbell, R.B.

    1993-01-01

    One of the possible consequences of disruptions in tokamaks is the generation of runaway electrons which can impact plasma facing components and cause damage, owing to high local energy deposition. This problem becomes more serious as the machine size and plasma current increase. Since large size and high currents are characteristics of proposed future machines, control of runaway generation is an important design consideration. A lumped circuit model for disruption runaway electron generation indicates that impurity concentration and type, as well as plasma motion, can strongly influence runaway behaviour. A comparison of disruption data from several runs on JET and DIII-D with model results demonstrate the effects of impurities, and plasma motion, on runaway number density and energy. The model is also applied to the calculation of runaway currents for ITER. (author). 16 refs, 13 figs

  2. Semiempirical model for nanoscale device simulations

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Petersen, Dan Erik; Smidstrup, Søren

    2010-01-01

    We present a semiempirical model for calculating electron transport in atomic-scale devices. The model is an extension of the extended Hückel method with a self-consistent Hartree potential that models the effect of an external bias and corresponding charge rearrangements in the device. It is also...... possible to include the effect of external gate potentials and continuum dielectric regions in the device. The model is used to study the electron transport through an organic molecule between gold surfaces, and it is demonstrated that the results are in closer agreement with experiments than ab initio...

  3. Modeling of magnetic particle suspensions for simulations

    CERN Document Server

    Satoh, Akira

    2017-01-01

    The main objective of the book is to highlight the modeling of magnetic particles with different shapes and magnetic properties, to provide graduate students and young researchers information on the theoretical aspects and actual techniques for the treatment of magnetic particles in particle-based simulations. In simulation, we focus on the Monte Carlo, molecular dynamics, Brownian dynamics, lattice Boltzmann and stochastic rotation dynamics (multi-particle collision dynamics) methods. The latter two simulation methods can simulate both the particle motion and the ambient flow field simultaneously. In general, specialized knowledge can only be obtained in an effective manner under the supervision of an expert. The present book is written to play such a role for readers who wish to develop the skill of modeling magnetic particles and develop a computer simulation program using their own ability. This book is therefore a self-learning book for graduate students and young researchers. Armed with this knowledge,...

  4. Modelling and Simulation of Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    velocity can be approximated by a Gaussian Markov process. Known approximate results for the first-passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on slender members of offshore structures is described. The wave elevation of the sea state is modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...

  5. Modelling and Simulation of Wave Loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1985-01-01

    velocity can be approximated by a Gaussian Markov process. Known approximate results for the first passage density or equivalently, the distribution of the extremes of wave loads are presented and compared with rather precise simulation results. It is demonstrated that the approximate results......A simple model of the wave load on stender members of offshore structures is described . The wave elevation of the sea stateis modelled by a stationary Gaussian process. A new procedure to simulate realizations of the wave loads is developed. The simulation method assumes that the wave particle...

  6. Modeling and simulation of discrete event systems

    CERN Document Server

    Choi, Byoung Kyu

    2013-01-01

    Computer modeling and simulation (M&S) allows engineers to study and analyze complex systems. Discrete-event system (DES)-M&S is used in modern management, industrial engineering, computer science, and the military. As computer speeds and memory capacity increase, so DES-M&S tools become more powerful and more widely used in solving real-life problems. Based on over 20 years of evolution within a classroom environment, as well as on decades-long experience in developing simulation-based solutions for high-tech industries, Modeling and Simulation of Discrete-Event Systems is the only book on

  7. Minimum-complexity helicopter simulation math model

    Science.gov (United States)

    Heffley, Robert K.; Mnich, Marc A.

    1988-01-01

    An example of a minimal complexity simulation helicopter math model is presented. Motivating factors are the computational delays, cost, and inflexibility of the very sophisticated math models now in common use. A helicopter model form is given which addresses each of these factors and provides better engineering understanding of the specific handling qualities features which are apparent to the simulator pilot. The technical approach begins with specification of features which are to be modeled, followed by a build up of individual vehicle components and definition of equations. Model matching and estimation procedures are given which enable the modeling of specific helicopters from basic data sources such as flight manuals. Checkout procedures are given which provide for total model validation. A number of possible model extensions and refinement are discussed. Math model computer programs are defined and listed.

  8. Particle-in-cell simulation of electron trajectories and irradiation uniformity in an annular cathode high current pulsed electron beam source

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei; Wang, Langping, E-mail: aplpwang@hit.edu.cn; Zhou, Guangxue; Wang, Xiaofeng

    2017-02-01

    Highlights: • The transmission process of electrons and irradiation uniformity was simulated. • Influence of the irradiation parameters on irradiation uniformity are discussed. • High irradiation uniformity can be obtained in a wide processing window. - Abstract: In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 mm and −15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source.

  9. Modeling of electron-specimen interaction in scanning electron microscope for e-beam metrology and inspection: challenges and perspectives

    Science.gov (United States)

    Suzuki, Makoto; Kameda, Toshimasa; Doi, Ayumi; Borisov, Sergey; Babin, Sergey

    2018-03-01

    The interpretation of scanning electron microscopy (SEM) images of the latest semiconductor devices is not intuitive and requires comparison with computed images based on theoretical modeling and simulations. For quantitative image prediction and geometrical reconstruction of the specimen structure, the accuracy of the physical model is essential. In this paper, we review the current models of electron-solid interaction and discuss their accuracy. We perform the comparison of the simulated results with our experiments of SEM overlay of under-layer, grain imaging of copper interconnect, and hole bottom visualization by angular selective detectors, and show that our model well reproduces the experimental results. Remaining issues for quantitative simulation are also discussed, including the accuracy of the charge dynamics, treatment of beam skirt, and explosive increase in computing time.

  10. Significance of matrix diagonalization in modelling inelastic electron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Z. [University of Ulm, Ulm 89081 (Germany); Hambach, R. [University of Ulm, Ulm 89081 (Germany); University of Jena, Jena 07743 (Germany); Kaiser, U.; Rose, H. [University of Ulm, Ulm 89081 (Germany)

    2017-04-15

    Electron scattering is always applied as one of the routines to investigate nanostructures. Nowadays the development of hardware offers more and more prospect for this technique. For example imaging nanostructures with inelastic scattered electrons may allow to produce component-sensitive images with atomic resolution. Modelling inelastic electron scattering is therefore essential for interpreting these images. The main obstacle to study inelastic scattering problem is its complexity. During inelastic scattering, incident electrons entangle with objects, and the description of this process involves a multidimensional array. Since the simulation usually involves fourdimensional Fourier transforms, the computation is highly inefficient. In this work we have offered one solution to handle the multidimensional problem. By transforming a high dimensional array into twodimensional array, we are able to perform matrix diagonalization and approximate the original multidimensional array with its twodimensional eigenvectors. Our procedure reduces the complicated multidimensional problem to a twodimensional problem. In addition, it minimizes the number of twodimensional problems. This method is very useful for studying multiple inelastic scattering. - Highlights: • 4D problems are involved in modelling inelastic electron scattering. • By means of matrix diagonalization, the 4D problems can be simplified as 2D problems. • The number of 2D problems is minimized by using this approach.

  11. Stochastic model of the spinning electron

    International Nuclear Information System (INIS)

    Simaciu, I.; Borsos, Z.

    2002-01-01

    In Stochastic Electrodynamics (SED) it is demonstrated that electrostatic interaction is the result of the scattering of the Classical Zero-Point Field (CZPF) background by the charged particles. In such models, the electron is modelled as a two-dimensional oscillator, which interacts with the electric component of the CZPF background. The electron with spin is not only an electric monopole but also a magnetic dipole. The interaction of the spin electron with the CZPF background is not only electric but also magnetic. We calculate the scattering cross-section of magnetic dipole in the situation when a magnetic field, variable in time B arrow = B 0 arrow sin ωt, acts over the rigid magnetic dipole given by the symmetry of the model. The cross-section of a magnetic dipole σ m must be equal to the cross-section of an electric monopole σ e . This equality between σ m and σ e cross-sections is motivated, too, by the fact that, in the model of the two-dimensional oscillator, the electric charge q e has the motion speed c. (authors)

  12. Xyce parallel electronic simulator : users' guide. Version 5.1.

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2009-11-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers. (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) Device models which are specifically tailored to meet Sandia's needs, including some radiation-aware devices (for Sandia users only). (4) Object-oriented code design and implementation using modern coding practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. Xyce is a parallel code in the most general sense of the phrase - a message passing parallel implementation - which allows it to run efficiently on the widest possible number of computing platforms. These include serial, shared-memory and distributed-memory parallel as well as heterogeneous platforms. Careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. The development of Xyce provides a platform for computational research and development aimed specifically at the needs of the Laboratory. With Xyce, Sandia has an 'in-house' capability with which both new electrical (e.g., device model development) and algorithmic (e.g., faster time-integration methods, parallel solver algorithms) research and development can be performed. As a result, Xyce is a

  13. Xyce Parallel Electronic Simulator : users' guide, version 4.1.

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Ting; Rankin, Eric Lamont; Thornquist, Heidi K.; Santarelli, Keith R.; Fixel, Deborah A.; Coffey, Todd Stirling; Russo, Thomas V.; Schiek, Richard Louis; Keiter, Eric Richard; Pawlowski, Roger Patrick

    2009-02-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: (1) Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). Note that this includes support for most popular parallel and serial computers. (2) Improved performance for all numerical kernels (e.g., time integrator, nonlinear and linear solvers) through state-of-the-art algorithms and novel techniques. (3) Device models which are specifically tailored to meet Sandia's needs, including some radiation-aware devices (for Sandia users only). (4) Object-oriented code design and implementation using modern coding practices that ensure that the Xyce Parallel Electronic Simulator will be maintainable and extensible far into the future. Xyce is a parallel code in the most general sense of the phrase - a message passing parallel implementation - which allows it to run efficiently on the widest possible number of computing platforms. These include serial, shared-memory and distributed-memory parallel as well as heterogeneous platforms. Careful attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. The development of Xyce provides a platform for computational research and development aimed specifically at the needs of the Laboratory. With Xyce, Sandia has an 'in-house' capability with which both new electrical (e.g., device model development) and algorithmic (e.g., faster time-integration methods, parallel solver algorithms) research and development can be performed. As a result, Xyce is a

  14. Computer Based Modelling and Simulation

    Indian Academy of Sciences (India)

    GENERAL I ARTICLE. Computer Based ... universities, and later did system analysis, ... sonal computers (PC) and low cost software packages and tools. They can serve as useful learning experience through student projects. Models are .... Let us consider a numerical example: to calculate the velocity of a trainer aircraft ...

  15. Dose point kernel simulation for monoenergetic electrons and radionuclides using Monte Carlo techniques.

    Science.gov (United States)

    Wu, J; Liu, Y L; Chang, S J; Chao, M M; Tsai, S Y; Huang, D E

    2012-11-01

    Monte Carlo (MC) simulation has been commonly used in the dose evaluation of radiation accidents and for medical purposes. The accuracy of simulated results is affected by the particle-tracking algorithm, cross-sectional database, random number generator and statistical error. The differences among MC simulation software packages must be validated. This study simulated the dose point kernel (DPK) and the cellular S-values of monoenergetic electrons ranging from 0.01 to 2 MeV and the radionuclides of (90)Y, (177)Lu and (103 m)Rh, using Fluktuierende Kaskade (FLUKA) and MC N-Particle Transport Code Version 5 (MCNP5). A 6-μm-radius cell model consisting of the cell surface, cytoplasm and cell nucleus was constructed for cellular S-value calculation. The mean absolute percentage errors (MAPEs) of the scaled DPKs, simulated using FLUKA and MCNP5, were 7.92, 9.64, 4.62, 3.71 and 3.84 % for 0.01, 0.1, 0.5, 1 and 2 MeV, respectively. For the three radionuclides, the MAPEs of the scaled DPKs were within 5 %. The maximum deviations of S(N←N), S(N←Cy) and S(N←CS) for the electron energy larger than 10 keV were 6.63, 6.77 and 5.24 %, respectively. The deviations for the self-absorbed S-values and cross-dose S-values of the three radionuclides were within 4 %. On the basis of the results of this study, it was concluded that the simulation results are consistent between FLUKA and MCNP5. However, there is a minor inconsistency for low energy range. The DPK and the cellular S-value should be used as the quality assurance tools before the MC simulation results are adopted as the gold standard.

  16. Thermal unit availability modeling in a regional simulation model

    International Nuclear Information System (INIS)

    Yamayee, Z.A.; Port, J.; Robinett, W.

    1983-01-01

    The System Analysis Model (SAM) developed under the umbrella of PNUCC's System Analysis Committee is capable of simulating the operation of a given load/resource scenario. This model employs a Monte-Carlo simulation to incorporate uncertainties. Among uncertainties modeled is thermal unit availability both for energy simulation (seasonal) and capacity simulations (hourly). This paper presents the availability modeling in the capacity and energy models. The use of regional and national data in deriving the two availability models, the interaction between the two and modifications made to the capacity model in order to reflect regional practices is presented. A sample problem is presented to show the modification process. Results for modeling a nuclear unit using NERC-GADS is presented

  17. Plasma disruption modeling and simulation

    International Nuclear Information System (INIS)

    Hassanein, A.

    1994-01-01

    Disruptions in tokamak reactors are considered a limiting factor to successful operation and reliable design. The behavior of plasma-facing components during a disruption is critical to the overall integrity of the reactor. Erosion of plasma facing-material (PFM) surfaces due to thermal energy dump during the disruption can severely limit the lifetime of these components and thus diminish the economic feasibility of the reactor. A comprehensive understanding of the interplay of various physical processes during a disruption is essential for determining component lifetime and potentially improving the performance of such components. There are three principal stages in modeling the behavior of PFM during a disruption. Initially, the incident plasma particles will deposit their energy directly on the PFM surface, heating it to a very high temperature where ablation occurs. Models for plasma-material interactions have been developed and used to predict material thermal evolution during the disruption. Within a few microseconds after the start of the disruption, enough material is vaporized to intercept most of the incoming plasma particles. Models for plasma-vapor interactions are necessary to predict vapor cloud expansion and hydrodynamics. Continuous heating of the vapor cloud above the material surface by the incident plasma particles will excite, ionize, and cause vapor atoms to emit thermal radiation. Accurate models for radiation transport in the vapor are essential for calculating the net radiated flux to the material surface which determines the final erosion thickness and consequently component lifetime. A comprehensive model that takes into account various stages of plasma-material interaction has been developed and used to predict erosion rates during reactor disruption, as well during induced disruption in laboratory experiments

  18. Modelling and simulating fire tube boiler performance

    DEFF Research Database (Denmark)

    Sørensen, K.; Condra, T.; Houbak, Niels

    2003-01-01

    A model for a flue gas boiler covering the flue gas and the water-/steam side has been formulated. The model has been formulated as a number of sub models that are merged into an overall model for the complete boiler. Sub models have been defined for the furnace, the convection zone (split in 2......: a zone submerged in water and a zone covered by steam), a model for the material in the boiler (the steel) and 2 models for resp. the water/steam zone (the boiling) and the steam. The dynamic model has been developed as a number of Differential-Algebraic-Equation system (DAE). Subsequently Mat......Lab/Simulink has been applied for carrying out the simulations. To be able to verify the simulated results experiments has been carried out on a full scale boiler plant....

  19. Two-point model for electron transport in EBT

    International Nuclear Information System (INIS)

    Chiu, S.C.; Guest, G.E.

    1980-01-01

    The electron transport in EBT is simulated by a two-point model corresponding to the central plasma and the edge. The central plasma is assumed to obey neoclassical collisionless transport. The edge plasma is assumed turbulent and modeled by Bohm diffusion. The steady-state temperatures and densities in both regions are obtained as functions of neutral influx and microwave power. It is found that as the neutral influx decreases and power increases, the edge density decreases while the core density increases. We conclude that if ring instability is responsible for the T-M mode transition, and if stability is correlated with cold electron density at the edge, it will depend sensitively on ambient gas pressure and microwave power

  20. A virtual laboratory notebook for simulation models.

    Science.gov (United States)

    Winfield, A J

    1998-01-01

    In this paper we describe how we have adopted the laboratory notebook as a metaphor for interacting with computer simulation models. This 'virtual' notebook stores the simulation output and meta-data (which is used to record the scientist's interactions with the simulation). The meta-data stored consists of annotations (equivalent to marginal notes in a laboratory notebook), a history tree and a log of user interactions. The history tree structure records when in 'simulation' time, and from what starting point in the tree changes are made to the parameters by the user. Typically these changes define a new run of the simulation model (which is represented as a new branch of the history tree). The tree shows the structure of the changes made to the simulation and the log is required to keep the order in which the changes occurred. Together they form a record which you would normally find in a laboratory notebook. The history tree is plotted in simulation parameter space. This shows the scientist's interactions with the simulation visually and allows direct manipulation of the parameter information presented, which in turn is used to control directly the state of the simulation. The interactions with the system are graphical and usually involve directly selecting or dragging data markers and other graphical control devices around in parameter space. If the graphical manipulators do not provide precise enough control then textual manipulation is still available which allows numerical values to be entered by hand. The Virtual Laboratory Notebook, by providing interesting interactions with the visual view of the history tree, provides a mechanism for giving the user complex and novel ways of interacting with biological computer simulation models.

  1. Bridging experiments, models and simulations

    DEFF Research Database (Denmark)

    Carusi, Annamaria; Burrage, Kevin; Rodríguez, Blanca

    2012-01-01

    Computational models in physiology often integrate functional and structural information from a large range of spatiotemporal scales from the ionic to the whole organ level. Their sophistication raises both expectations and skepticism concerning how computational methods can improve our...... understanding of living organisms and also how they can reduce, replace, and refine animal experiments. A fundamental requirement to fulfill these expectations and achieve the full potential of computational physiology is a clear understanding of what models represent and how they can be validated. The present...... that contributes to defining the specific aspects of cardiac electrophysiology the MSE system targets, rather than being only an external test, and that this is driven by advances in experimental and computational methods and the combination of both....

  2. Non-local electron transport validation using 2D DRACO simulations

    Science.gov (United States)

    Cao, Duc; Chenhall, Jeff; Moll, Eli; Prochaska, Alex; Moses, Gregory; Delettrez, Jacques; Collins, Tim

    2012-10-01

    Comparison of 2D DRACO simulations, using a modified versionfootnotetextprivate communications with M. Marinak and G. Zimmerman, LLNL. of the Schurtz, Nicolai and Busquet (SNB) algorithmfootnotetextSchurtz, Nicolai and Busquet, ``A nonlocal electron conduction model for multidimensional radiation hydrodynamics codes,'' Phys. Plasmas 7, 4238(2000). for non-local electron transport, with direct drive shock timing experimentsfootnotetextT. Boehly, et. al., ``Multiple spherically converging shock waves in liquid deuterium,'' Phys. Plasmas 18, 092706(2011). and with the Goncharov non-local modelfootnotetextV. Goncharov, et. al., ``Early stage of implosion in inertial confinement fusion: Shock timing and perturbation evolution,'' Phys. Plasmas 13, 012702(2006). in 1D LILAC will be presented. Addition of an improved SNB non-local electron transport algorithm in DRACO allows direct drive simulations with no need for an electron conduction flux limiter. Validation with shock timing experiments that mimic the laser pulse profile of direct drive ignition targets gives a higher confidence level in the predictive capability of the DRACO code. This research was supported by the University of Rochester Laboratory for Laser Energetics.

  3. Monte Carlo Simulation of a Linear Accelerator and Electron Beam Parameters Used in Radiotherapy

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Bahreyni Toossi

    2009-06-01

    Full Text Available Introduction: In recent decades, several Monte Carlo codes have been introduced for research and medical applications. These methods provide both accurate and detailed calculation of particle transport from linear accelerators. The main drawback of Monte Carlo techniques is the extremely long computing time that is required in order to obtain a dose distribution with good statistical accuracy. Material and Methods: In this study, the MCNP-4C Monte Carlo code was used to simulate the electron beams generated by a Neptun 10 PC linear accelerator. The depth dose curves and related parameters to depth dose and beam profiles were calculated for 6, 8 and 10 MeV electron beams with different field sizes and these data were compared with the corresponding measured values. The actual dosimetry was performed by employing a Welhofer-Scanditronix dose scanning system, semiconductor detectors and ionization chambers. Results: The result showed good agreement (better than 2% between calculated and measured depth doses and lateral dose profiles for all energies in different field sizes. Also good agreements were achieved between calculated and measured related electron beam parameters such as E0, Rq, Rp and R50. Conclusion: The simulated model of the linac developed in this study is capable of computing electron beam data in a water phantom for different field sizes and the resulting data can be used to predict the dose distributions in other complex geometries.

  4. Classical Electron Model with QED Corrections

    OpenAIRE

    Lenk, Ron

    2010-01-01

    In this article we build a metric for a classical general relativistic electron model with QED corrections. We calculate the stress-energy tensor for the radiative corrections to the Coulomb potential in both the near-field and far-field approximations. We solve the three field equations in both cases by using a perturbative expansion to first order in alpha (the fine-structure constant) while insisting that the usual (+, +, -, -) structure of the stress-energy tensor is maintained. The resul...

  5. Models of fast-electron penetration

    International Nuclear Information System (INIS)

    Perry, D.J.; Raisis, S.K.

    1994-01-01

    We introduce multiple scattering models of charged-particle penetration which are based on the previous analyses of Yang and Perry. Our development removes the main limitations of the Fermi-Eyges approach while retaining its considerable potential as a theory which is useful for applied work. We illustrate key predictions with sample calculations that are of particular interest in therapeutic applications, 5-20 MeV electrons incident on water. 8 refs., 5 figs

  6. Quantum mechanical ab initio simulation of the electron screening effect in metal deuteride crystals

    Energy Technology Data Exchange (ETDEWEB)

    Huke, A.; Chun, S.M.; Biller, A.; Heide, P. [Technische Universitaet Berlin, Institut fuer Optik und Atomare Physik, Berlin (Germany); Czerski, K. [Technische Universitaet Berlin, Institut fuer Optik und Atomare Physik, Berlin (Germany); University of Szczecin, Institute of Physics, Szczecin (Poland)

    2008-02-15

    In antecedent experiments the electron screening energies of the d+d reactions in metallic environments have been determined to be enhanced by an order of magnitude in comparison to the case of gaseous deuterium targets. The analytical models describing averaged material properties have not been able to explain the experimental results so far. Therefore, a first effort has been undertaken to simulate the dynamics of reacting deuterons in a metallic lattice by means of an ab initio Hartree-Fock calculation of the total electrostatic force between the lattice and the successively approaching deuterons via path integration. The calculations have been performed for Li and Ta, clearly showing a migration of electrons from host metallic to the deuterium atoms. However, in order to avoid more of the necessary simplifications in the model the utilization of a massive parallel supercomputer would be required. (orig.) 3.

  7. Kinetic modelling of runaway electron avalanches in tokamak plasmas

    International Nuclear Information System (INIS)

    Nilsson, E; Peysson, Y; Saint-Laurent, F; Decker, J; Granetz, R S; Vlainic, M

    2015-01-01

    Runaway electrons can be generated in tokamak plasmas if the accelerating force from the toroidal electric field exceeds the collisional drag force owing to Coulomb collisions with the background plasma. In ITER, disruptions are expected to generate runaway electrons mainly through knock-on collisions (Hender et al 2007 Nucl. Fusion 47 S128–202), where enough momentum can be transferred from existing runaways to slow electrons to transport the latter beyond a critical momentum, setting off an avalanche of runaway electrons. Since knock-on runaways are usually scattered off with a significant perpendicular component of the momentum with respect to the local magnetic field direction, these particles are highly magnetized. Consequently, the momentum dynamics require a full 3D kinetic description, since these electrons are highly sensitive to the magnetic non-uniformity of a toroidal configuration. For this purpose, a bounce-averaged knock-on source term is derived. The generation of runaway electrons from the combined effect of Dreicer mechanism and knock-on collision process is studied with the code LUKE, a solver of the 3D linearized bounce-averaged relativistic electron Fokker–Planck equation (Decker and Peysson 2004 DKE: a fast numerical solver for the 3D drift kinetic equation Report EUR-CEA-FC-1736, Euratom-CEA), through the calculation of the response of the electron distribution function to a constant parallel electric field. The model, which has been successfully benchmarked against the standard Dreicer runaway theory now describes the runaway generation by knock-on collisions as proposed by Rosenbluth (Rosenbluth and Putvinski 1997 Nucl. Fusion 37 1355–62). This paper shows that the avalanche effect can be important even in non-disruptive scenarios. Runaway formation through knock-on collisions is found to be strongly reduced when taking place off the magnetic axis, since trapped electrons can not contribute to the runaway electron population. Finally

  8. Animated-simulation modeling facilitates clinical-process costing.

    Science.gov (United States)

    Zelman, W N; Glick, N D; Blackmore, C C

    2001-09-01

    Traditionally, the finance department has assumed responsibility for assessing process costs in healthcare organizations. To enhance process-improvement efforts, however, many healthcare providers need to include clinical staff in process cost analysis. Although clinical staff often use electronic spreadsheets to model the cost of specific processes, PC-based animated-simulation tools offer two major advantages over spreadsheets: they allow clinicians to interact more easily with the costing model so that it more closely represents the process being modeled, and they represent cost output as a cost range rather than as a single cost estimate, thereby providing more useful information for decision making.

  9. MODELLING, SIMULATING AND OPTIMIZING BOILERS

    DEFF Research Database (Denmark)

    Sørensen, K.; Condra, T.; Houbak, Niels

    2003-01-01

    , and the total stress level (i.e. stresses introduced due to internal pressure plus stresses introduced due to temperature gradients) must always be kept below the allowable stress level. In this way, the increased water-/steam space that should allow for better dynamic performance, in the end causes limited...... freedom with respect to dynamic operation of the plant. By means of an objective function including as well the price of the plant as a quantification of the value of dynamic operation of the plant an optimization is carried out. The dynamic model of the boiler plant is applied to define parts...

  10. Application of Macro Response Monte Carlo method for electron spectrum simulation

    International Nuclear Information System (INIS)

    Perles, L.A.; Almeida, A. de

    2007-01-01

    During the past years several variance reduction techniques for Monte Carlo electron transport have been developed in order to reduce the electron computation time transport for absorbed dose distribution. We have implemented the Macro Response Monte Carlo (MRMC) method to evaluate the electron spectrum which can be used as a phase space input for others simulation programs. Such technique uses probability distributions for electron histories previously simulated in spheres (called kugels). These probabilities are used to sample the primary electron final state, as well as the creation secondary electrons and photons. We have compared the MRMC electron spectra simulated in homogeneous phantom against the Geant4 spectra. The results showed an agreement better than 6% in the spectra peak energies and that MRMC code is up to 12 time faster than Geant4 simulations

  11. Evaluation of backscatter dose from internal lead shielding in clinical electron beams using EGSnrc Monte Carlo simulations.

    Science.gov (United States)

    De Vries, Rowen J; Marsh, Steven

    2015-11-08

    Internal lead shielding is utilized during superficial electron beam treatments of the head and neck, such as lip carcinoma. Methods for predicting backscattered dose include the use of empirical equations or performing physical measurements. The accuracy of these empirical equations required verification for the local electron beams. In this study, a Monte Carlo model of a Siemens Artiste linac was developed for 6, 9, 12, and 15 MeV electron beams using the EGSnrc MC package. The model was verified against physical measurements to an accuracy of better than 2% and 2mm. Multiple MC simulations of lead interfaces at different depths, corresponding to mean electron energies in the range of 0.2-14 MeV at the interfaces, were performed to calculate electron backscatter values. The simulated electron backscatter was compared with current empirical equations to ascertain their accuracy. The major finding was that the current set of backscatter equations does not accurately predict electron backscatter, particularly in the lower energies region. A new equation was derived which enables estimation of electron backscatter factor at any depth upstream from the interface for the local treatment machines. The derived equation agreed to within 1.5% of the MC simulated electron backscatter at the lead interface and upstream positions. Verification of the equation was performed by comparing to measurements of the electron backscatter factor using Gafchromic EBT2 film. These results show a mean value of 0.997 ± 0.022 to 1σ of the predicted values of electron backscatter. The new empirical equation presented can accurately estimate electron backscatter factor from lead shielding in the range of 0.2 to 14 MeV for the local linacs.

  12. Initial Self-Consistent 3D Electron-Cloud Simulations of the LHC Beam with the Code WARP+POSINST

    International Nuclear Information System (INIS)

    Vay, J; Furman, M A; Cohen, R H; Friedman, A; Grote, D P

    2005-01-01

    We present initial results for the self-consistent beam-cloud dynamics simulations for a sample LHC beam, using a newly developed set of modeling capability based on a merge [1] of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP [2] and the electron-cloud code POSINST [3]. Although the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its lattice elements are realistically modeled, as is the beam and the electron cloud dynamics. The simulated mechanisms for generation and absorption of the electrons at the walls are based on previously validated models available in POSINST [3, 4

  13. Advanced training simulator models. Implementation and validation

    International Nuclear Information System (INIS)

    Borkowsky, Jeffrey; Judd, Jerry; Belblidia, Lotfi; O'farrell, David; Andersen, Peter

    2008-01-01

    Modern training simulators are required to replicate plant data for both thermal-hydraulic and neutronic response. Replication is required such that reactivity manipulation on the simulator properly trains the operator for reactivity manipulation at the plant. This paper discusses advanced models which perform this function in real-time using the coupled code system THOR/S3R. This code system models the all fluids systems in detail using an advanced, two-phase thermal-hydraulic a model. The nuclear core is modeled using an advanced, three-dimensional nodal method and also by using cycle-specific nuclear data. These models are configured to run interactively from a graphical instructor station or handware operation panels. The simulator models are theoretically rigorous and are expected to replicate the physics of the plant. However, to verify replication, the models must be independently assessed. Plant data is the preferred validation method, but plant data is often not available for many important training scenarios. In the absence of data, validation may be obtained by slower-than-real-time transient analysis. This analysis can be performed by coupling a safety analysis code and a core design code. Such a coupling exists between the codes RELAP5 and SIMULATE-3K (S3K). RELAP5/S3K is used to validate the real-time model for several postulated plant events. (author)

  14. Regularization modeling for large-eddy simulation

    NARCIS (Netherlands)

    Geurts, Bernardus J.; Holm, D.D.

    2003-01-01

    A new modeling approach for large-eddy simulation (LES) is obtained by combining a "regularization principle" with an explicit filter and its inversion. This regularization approach allows a systematic derivation of the implied subgrid model, which resolves the closure problem. The central role of

  15. Analytical system dynamics modeling and simulation

    CERN Document Server

    Fabien, Brian C

    2008-01-01

    This book offering a modeling technique based on Lagrange's energy method includes 125 worked examples. Using this technique enables one to model and simulate systems as diverse as a six-link, closed-loop mechanism or a transistor power amplifier.

  16. Hybrid simulation models of production networks

    CERN Document Server

    Kouikoglou, Vassilis S

    2001-01-01

    This book is concerned with a most important area of industrial production, that of analysis and optimization of production lines and networks using discrete-event models and simulation. The book introduces a novel approach that combines analytic models and discrete-event simulation. Unlike conventional piece-by-piece simulation, this method observes a reduced number of events between which the evolution of the system is tracked analytically. Using this hybrid approach, several models are developed for the analysis of production lines and networks. The hybrid approach combines speed and accuracy for exceptional analysis of most practical situations. A number of optimization problems, involving buffer design, workforce planning, and production control, are solved through the use of hybrid models.

  17. Dynamic modeling and simulation of wind turbines

    International Nuclear Information System (INIS)

    Ghafari Seadat, M.H.; Kheradmand Keysami, M.; Lari, H.R.

    2002-01-01

    Using wind energy for generating electricity in wind turbines is a good way for using renewable energies. It can also help to protect the environment. The main objective of this paper is dynamic modeling by energy method and simulation of a wind turbine aided by computer. In this paper, the equations of motion are extracted for simulating the system of wind turbine and then the behavior of the system become obvious by solving the equations. The turbine is considered with three blade rotor in wind direction, induced generator that is connected to the network and constant revolution for simulation of wind turbine. Every part of the wind turbine should be simulated for simulation of wind turbine. The main parts are blades, gearbox, shafts and generator

  18. Model potential for electron scattering from rubidium

    Energy Technology Data Exchange (ETDEWEB)

    Gien, T.E. (Memorial Univ. of Newfoundland, St. John' s, NF (Canada). Dept. of Physics)

    1992-11-28

    An analytic model potential for the e[sup -]-Rb[sup +] system is generated from experimental data, using an iteration method. The potential obtained can reproduce rather accurately the energy levels of rubidium. We employed it in the calculation of elastic differential cross sections for electron (and positron) scatterings from rubidium in the conventional Glauber approximation. The differential cross sections calculated in the model potential approach are compared to those in the frozen-core approach, employing either the Clementi-Roetti or the Szasz-McGinn wavefunctions. The core correlation and polarization effects are found to significantly affect the cross section results. (author).

  19. Model potential for electron scattering from rubidium

    International Nuclear Information System (INIS)

    Gien, T.E.

    1992-01-01

    An analytic model potential for the e - -Rb + system is generated from experimental data, using an iteration method. The potential obtained can reproduce rather accurately the energy levels of rubidium. We employed it in the calculation of elastic differential cross sections for electron (and positron) scatterings from rubidium in the conventional Glauber approximation. The differential cross sections calculated in the model potential approach are compared to those in the frozen-core approach, employing either the Clementi-Roetti or the Szasz-McGinn wavefunctions. The core correlation and polarization effects are found to significantly affect the cross section results. (author)

  20. Plant model of KIPT neutron source facility simulator

    International Nuclear Information System (INIS)

    Cao, Yan; Wei, Thomas Y.; Grelle, Austin L.; Gohar, Yousry

    2016-01-01

    Argonne National Laboratory (ANL) of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine are collaborating on constructing a neutron source facility at KIPT, Kharkov, Ukraine. The facility has 100-kW electron beam driving a subcritical assembly (SCA). The electron beam interacts with a natural uranium target or a tungsten target to generate neutrons, and deposits its power in the target zone. The total fission power generated in SCA is about 300 kW. Two primary cooling loops are designed to remove 100-kW and 300-kW from the target zone and the SCA, respectively. A secondary cooling system is coupled with the primary cooling system to dispose of the generated heat outside the facility buildings to the atmosphere. In addition, the electron accelerator has a low efficiency for generating the electron beam, which uses another secondary cooling loop to remove the generated heat from the accelerator primary cooling loop. One of the main functions the KIPT neutron source facility is to train young nuclear specialists; therefore, ANL has developed the KIPT Neutron Source Facility Simulator for this function. In this simulator, a Plant Control System and a Plant Protection System were developed to perform proper control and to provide automatic protection against unsafe and improper operation of the facility during the steady-state and the transient states using a facility plant model. This report focuses on describing the physics of the plant model and provides several test cases to demonstrate its capabilities. The plant facility model uses the PYTHON script language. It is consistent with the computer language of the plant control system. It is easy to integrate with the simulator without an additional interface, and it is able to simulate the transients of the cooling systems with system control variables changing on real-time.

  1. Plant model of KIPT neutron source facility simulator

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yan [Argonne National Lab. (ANL), Argonne, IL (United States); Wei, Thomas Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Grelle, Austin L. [Argonne National Lab. (ANL), Argonne, IL (United States); Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-02-01

    Argonne National Laboratory (ANL) of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine are collaborating on constructing a neutron source facility at KIPT, Kharkov, Ukraine. The facility has 100-kW electron beam driving a subcritical assembly (SCA). The electron beam interacts with a natural uranium target or a tungsten target to generate neutrons, and deposits its power in the target zone. The total fission power generated in SCA is about 300 kW. Two primary cooling loops are designed to remove 100-kW and 300-kW from the target zone and the SCA, respectively. A secondary cooling system is coupled with the primary cooling system to dispose of the generated heat outside the facility buildings to the atmosphere. In addition, the electron accelerator has a low efficiency for generating the electron beam, which uses another secondary cooling loop to remove the generated heat from the accelerator primary cooling loop. One of the main functions the KIPT neutron source facility is to train young nuclear specialists; therefore, ANL has developed the KIPT Neutron Source Facility Simulator for this function. In this simulator, a Plant Control System and a Plant Protection System were developed to perform proper control and to provide automatic protection against unsafe and improper operation of the facility during the steady-state and the transient states using a facility plant model. This report focuses on describing the physics of the plant model and provides several test cases to demonstrate its capabilities. The plant facility model uses the PYTHON script language. It is consistent with the computer language of the plant control system. It is easy to integrate with the simulator without an additional interface, and it is able to simulate the transients of the cooling systems with system control variables changing on real-time.

  2. Regional model simulations of New Zealand climate

    Science.gov (United States)

    Renwick, James A.; Katzfey, Jack J.; Nguyen, Kim C.; McGregor, John L.

    1998-03-01

    Simulation of New Zealand climate is examined through the use of a regional climate model nested within the output of the Commonwealth Scientific and Industrial Research Organisation nine-level general circulation model (GCM). R21 resolution GCM output is used to drive a regional model run at 125 km grid spacing over the Australasian region. The 125 km run is used in turn to drive a simulation at 50 km resolution over New Zealand. Simulations with a full seasonal cycle are performed for 10 model years. The focus is on the quality of the simulation of present-day climate, but results of a doubled-CO2 run are discussed briefly. Spatial patterns of mean simulated precipitation and surface temperatures improve markedly as horizontal resolution is increased, through the better resolution of the country's orography. However, increased horizontal resolution leads to a positive bias in precipitation. At 50 km resolution, simulated frequency distributions of daily maximum/minimum temperatures are statistically similar to those of observations at many stations, while frequency distributions of daily precipitation appear to be statistically different to those of observations at most stations. Modeled daily precipitation variability at 125 km resolution is considerably less than observed, but is comparable to, or exceeds, observed variability at 50 km resolution. The sensitivity of the simulated climate to changes in the specification of the land surface is discussed briefly. Spatial patterns of the frequency of extreme temperatures and precipitation are generally well modeled. Under a doubling of CO2, the frequency of precipitation extremes changes only slightly at most locations, while air frosts become virtually unknown except at high-elevation sites.

  3. Xyce parallel electronic simulator users guide, version 6.0.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Thornquist, Heidi K.; Verley, Jason C.; Fixel, Deborah A.; Coffey, Todd S; Pawlowski, Roger P; Warrender, Christina E.; Baur, David Gregory.

    2013-08-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). This includes support for most popular parallel and serial computers. A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models. Device models that are specifically tailored to meet Sandias needs, including some radiationaware devices (for Sandia users only). Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase a message passing parallel implementation which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows.

  4. Xyce parallel electronic simulator users' guide, Version 6.0.1.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Thornquist, Heidi K.; Verley, Jason C.; Fixel, Deborah A.; Coffey, Todd S; Pawlowski, Roger P; Warrender, Christina E.; Baur, David Gregory.

    2014-01-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). This includes support for most popular parallel and serial computers. A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models. Device models that are specifically tailored to meet Sandias needs, including some radiationaware devices (for Sandia users only). Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase a message passing parallel implementation which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows.

  5. Xyce parallel electronic simulator users guide, version 6.1

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R; Mei, Ting; Russo, Thomas V.; Schiek, Richard Louis; Sholander, Peter E.; Thornquist, Heidi K.; Verley, Jason C.; Baur, David Gregory

    2014-03-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas; Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). This includes support for most popular parallel and serial computers; A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models; Device models that are specifically tailored to meet Sandia's needs, including some radiationaware devices (for Sandia users only); and Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase-a message passing parallel implementation-which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows.

  6. Xyce™ Parallel Electronic Simulator Users' Guide, Version 6.5.

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Aadithya, Karthik V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Schiek, Richard L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation; Verley, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electrical Models and Simulation

    2016-06-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been designed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: Capability to solve extremely large circuit problems by supporting large-scale parallel computing platforms (up to thousands of processors). This includes support for most popular parallel and serial computers. A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models. Device models that are specifically tailored to meet Sandia's needs, including some radiation- aware devices (for Sandia users only). Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase -- a message passing parallel implementation -- which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows. The information herein is subject to change without notice. Copyright © 2002-2016 Sandia Corporation. All rights reserved.

  7. Xyce Parallel Electronic Simulator Users' Guide Version 6.8

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Eric R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aadithya, Karthik Venkatraman [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mei, Ting [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Russo, Thomas V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schiek, Richard L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thornquist, Heidi K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Verley, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-10-01

    This manual describes the use of the Xyce Parallel Electronic Simulator. Xyce has been de- signed as a SPICE-compatible, high-performance analog circuit simulator, and has been written to support the simulation needs of the Sandia National Laboratories electrical designers. This development has focused on improving capability over the current state-of-the-art in the following areas: Capability to solve extremely large circuit problems by supporting large-scale parallel com- puting platforms (up to thousands of processors). This includes support for most popular parallel and serial computers. A differential-algebraic-equation (DAE) formulation, which better isolates the device model package from solver algorithms. This allows one to develop new types of analysis without requiring the implementation of analysis-specific device models. Device models that are specifically tailored to meet Sandia's needs, including some radiation- aware devices (for Sandia users only). Object-oriented code design and implementation using modern coding practices. Xyce is a parallel code in the most general sense of the phrase$-$ a message passing parallel implementation $-$ which allows it to run efficiently a wide range of computing platforms. These include serial, shared-memory and distributed-memory parallel platforms. Attention has been paid to the specific nature of circuit-simulation problems to ensure that optimal parallel efficiency is achieved as the number of processors grows.

  8. Landscape Modelling and Simulation Using Spatial Data

    Directory of Open Access Journals (Sweden)

    Amjed Naser Mohsin AL-Hameedawi

    2017-08-01

    Full Text Available In this paper a procedure was performed for engendering spatial model of landscape acclimated to reality simulation. This procedure based on combining spatial data and field measurements with computer graphics reproduced using Blender software. Thereafter that we are possible to form a 3D simulation based on VIS ALL packages. The objective was to make a model utilising GIS, including inputs to the feature attribute data. The objective of these efforts concentrated on coordinating a tolerable spatial prototype, circumscribing facilitation scheme and outlining the intended framework. Thus; the eventual result was utilized in simulation form. The performed procedure contains not only data gathering, fieldwork and paradigm providing, but extended to supply a new method necessary to provide the respective 3D simulation mapping production, which authorises the decision makers as well as investors to achieve permanent acceptance an independent navigation system for Geoscience applications.

  9. Quantitative interface models for simulating microstructure evolution

    International Nuclear Information System (INIS)

    Zhu, J.Z.; Wang, T.; Zhou, S.H.; Liu, Z.K.; Chen, L.Q.

    2004-01-01

    To quantitatively simulate microstructural evolution in real systems, we investigated three different interface models: a sharp-interface model implemented by the software DICTRA and two diffuse-interface models which use either physical order parameters or artificial order parameters. A particular example is considered, the diffusion-controlled growth of a γ ' precipitate in a supersaturated γ matrix in Ni-Al binary alloys. All three models use the thermodynamic and kinetic parameters from the same databases. The temporal evolution profiles of composition from different models are shown to agree with each other. The focus is on examining the advantages and disadvantages of each model as applied to microstructure evolution in alloys

  10. A queuing model for road traffic simulation

    International Nuclear Information System (INIS)

    Guerrouahane, N.; Aissani, D.; Bouallouche-Medjkoune, L.; Farhi, N.

    2015-01-01

    We present in this article a stochastic queuing model for the raod traffic. The model is based on the M/G/c/c state dependent queuing model, and is inspired from the deterministic Godunov scheme for the road traffic simulation. We first propose a variant of M/G/c/c state dependent model that works with density-flow fundamental diagrams rather than density-speed relationships. We then extend this model in order to consider upstream traffic demand as well as downstream traffic supply. Finally, we show how to model a whole raod by concatenating raod sections as in the deterministic Godunov scheme

  11. Clock error models for simulation and estimation

    International Nuclear Information System (INIS)

    Meditch, J.S.

    1981-10-01

    Mathematical models for the simulation and estimation of errors in precision oscillators used as time references in satellite navigation systems are developed. The results, based on all currently known oscillator error sources, are directly implementable on a digital computer. The simulation formulation is sufficiently flexible to allow for the inclusion or exclusion of individual error sources as desired. The estimation algorithms, following from Kalman filter theory, provide directly for the error analysis of clock errors in both filtering and prediction

  12. Modeling and simulation goals and accomplishments

    International Nuclear Information System (INIS)

    Turinsky, P.

    2013-01-01

    The CASL (Consortium for Advanced Simulation of Light Water Reactors) mission is to develop and apply the Virtual Reactor simulator (VERA) to optimise nuclear power in terms of capital and operating costs, of nuclear waste production and of nuclear safety. An efficient and reliable virtual reactor simulator relies on 3-dimensional calculations, accurate physics models and code coupling. Advances in computer hardware, along with comparable advances in numerical solvers make the VERA project achievable. This series of slides details the VERA project and presents the specificities and performance of the codes involved in the project and ends by listing the computing needs

  13. Materials for the nuclear - Modelling and simulation of structure materials

    International Nuclear Information System (INIS)

    Berthoud, Georges; Ducros, Gerard; Feron, Damien; Guerin, Yannick; Latge, Christian; Limoge, Yves; Santarini, Gerard; Seiler, Jean-Marie; Vernaz, Etienne; Cappelaere, Chantal; Andrieux, Catherine; Athenes, Manuel; Baldinozzi, Guido; Bechade, Jean-Luc; Bonin, Bernard; Boutard, Jean-Louis; Brechet, Yves; Bruneval, Fabien; Carassou, Sebastien; Castelier, Etienne; Chartier, Alain; Clouet, Emmanuel; Marinica, Mihai-Cosmin; Crocombette, Jean-Paul; Dupuy, Laurent; Forget, Pierre; Fu, Chu Chun; Garnier, Jerome; Gelebart, Lionel; Henry, Jean; Jourdan, Thomas; Luneville, Laurence; Marini, Bernard; Meslin, Estelle; Nastar, Maylise; Onimus, Fabien; Poussard, Christophe; Proville, Laurent; Ribis, Joel; Robertson, Christian; Rodney, David; Roma, Guido; Sauzay, Maxime; Simeone, David; Soisson, Frederic; Tanguy, Benoit; Toffolon-Masclet, Caroline; Trocellier, Patrick; Van Brutzel, Laurent; Ventelon, Usa; Vincent, Ludovic; Willaime, Francois; Yvon, Pascal; Behar, Christophe; Provitina, Olivier; Lecomte, Michael; Forestier, Alain; Bender, Alexandra; Parisot, Jean-Francois; Finot, Pierre

    2016-01-01

    This collective publication proposes presentations of scientific approaches implemented to model and simulate the behaviour of materials submitted to irradiation, of associated experimental methods, and of some recent important results. After an introduction presenting the various materials used in different types of nuclear reactors (PWR, etc.), the effects of irradiation at the macroscopic or at the atomic scale, and the multi-scale (time and space) approach to the modelling of these materials, a chapter proposes an overview of modelling tools: multi-scale approach, electronic calculations for condensed matter, inter-atomic potentials, molecular dynamics simulation, thermodynamic and medium force potentials, phase diagrams, simulation of primary damages in reactor materials, kinetic models, dislocation dynamics, production of microstructures for simulation, crystalline visco-plasticity, homogenization methods in continuum mechanics, local approach and probabilistic approach in material fracture. The next part presents tools for experimental validation: tools for microscopic characterization or for mechanical characterization, experimental reactors and tests in atomic pile, tools for irradiation by charged particles. The next chapters presents different examples of thermodynamic and kinetic modelling in the case of various alloys (zirconium alloys, iron-chromium alloys, silicon carbide, austenitic alloys), of plasticity and failure modelling

  14. A contribution to the electron-beam surface-melting process of metallic materials. Numerical simulation and experimental verification

    International Nuclear Information System (INIS)

    Bruckner, A.

    1996-08-01

    For the optimization of the surface melting process it is necessary to make many different experiments. Therefore, the simulation of the surface melting process becomes a major role for the optimization. Most of the simulations, developed for the laser surface melting process, are not usable for the electron-beam surface melting process, because of the different energy input and the possibility of high frequent movement of the electron-beam. In this thesis, a calculation model for electron-beam surface melting is presented. For this numerical simulation a variable volume source is used, which moves in axial direction with the same velocity as the vapor cavity into the material. With this calculation model also the high frequent movement of the electron-beam may be taken into account. The electron-beam diameter is measured with a method of drilling holes with short electron-beam pulses in thin foils. The diameter of the holes depends on the pulse length and reaches a maximal value, which is used for the diameter of the volume source in the calculation. The crack-formation, seen in many treated surfaces, is examined with the Acoustic-Emission Testing. The possibilities of the electron-beam surface melting process are shown with some experiments for different requirements of the treated surfaces, like increasing the hardness, reducing the porosity of a sintered material and the alloying of tin in an aluminium-silicon surface. (author)

  15. Monte Carlo simulations of secondary electron emission due to ion beam milling

    Energy Technology Data Exchange (ETDEWEB)

    Mahady, Kyle [Univ. of Tennessee, Knoxville, TN (United States); Tan, Shida [Intel Corp., Santa Clara, CA (United States); Greenzweig, Yuval [Intel Israel Ltd., Haifa (Israel); Livengood, Richard [Intel Corp., Santa Clara, CA (United States); Raveh, Amir [Intel Israel Ltd., Haifa (Israel); Fowlkes, Jason D. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rack, Philip [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-07-01

    We present a Monte Carlo simulation study of secondary electron emission resulting from focused ion beam milling of a copper target. The basis of this study is a simulation code which simulates ion induced excitation and emission of secondary electrons, in addition to simulating focused ion beam sputtering and milling. This combination of features permits the simulation of the interaction between secondary electron emission, and the evolving target geometry as the ion beam sputters material. Previous ion induced SE Monte Carlo simulation methods have been restricted to predefined target geometries, while the dynamic target in the presented simulations makes this study relevant to image formation in ion microscopy, and chemically assisted ion beam etching, where the relationship between sputtering, and its effects on secondary electron emission, is important. We focus on a copper target, and validate our simulation against experimental data for a range of: noble gas ions, ion energies, ion/substrate angles and the energy distribution of the secondary electrons. We then provide a detailed account of the emission of secondary electrons resulting from ion beam milling; we quantify both the evolution of the yield as high aspect ratio valleys are milled, as well as the emission of electrons within these valleys that do not escape the target, but which are important to the secondary electron contribution to chemically assisted ion induced etching.

  16. Simulation Modeling of Software Development Processes

    Science.gov (United States)

    Calavaro, G. F.; Basili, V. R.; Iazeolla, G.

    1996-01-01

    A simulation modeling approach is proposed for the prediction of software process productivity indices, such as cost and time-to-market, and the sensitivity analysis of such indices to changes in the organization parameters and user requirements. The approach uses a timed Petri Net and Object Oriented top-down model specification. Results demonstrate the model representativeness, and its usefulness in verifying process conformance to expectations, and in performing continuous process improvement and optimization.

  17. Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory

    International Nuclear Information System (INIS)

    Tait, E W; Payne, M C; Ratcliff, L E; Haynes, P D; Hine, N D M

    2016-01-01

    Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable. (paper)

  18. Validation of the simulator neutronics model

    International Nuclear Information System (INIS)

    Gregory, M.V.

    1984-01-01

    The neutronics model in the SRP reactor training simulator computes the variation with time of the neutron population in the reactor core. The power output of a reactor is directly proportional to the neutron population, thus in a very real sense the neutronics model determines the response of the simulator. The geometrical complexity of the reactor control system in SRP reactors requires the neutronics model to provide a detailed, 3D representation of the reactor core. Existing simulator technology does not allow such a detailed representation to run in real-time in a minicomputer environment, thus an entirely different approach to the problem was required. A prompt jump method has been developed in answer to this need

  19. Analyzing Strategic Business Rules through Simulation Modeling

    Science.gov (United States)

    Orta, Elena; Ruiz, Mercedes; Toro, Miguel

    Service Oriented Architecture (SOA) holds promise for business agility since it allows business process to change to meet new customer demands or market needs without causing a cascade effect of changes in the underlying IT systems. Business rules are the instrument chosen to help business and IT to collaborate. In this paper, we propose the utilization of simulation models to model and simulate strategic business rules that are then disaggregated at different levels of an SOA architecture. Our proposal is aimed to help find a good configuration for strategic business objectives and IT parameters. The paper includes a case study where a simulation model is built to help business decision-making in a context where finding a good configuration for different business parameters and performance is too complex to analyze by trial and error.

  20. Self-consistent nonlinear simulations of high-power free-electron lasers

    International Nuclear Information System (INIS)

    Freund, H.P.; Jackson, R.H.

    1993-01-01

    Two 3-D nonlinear formulations of FEL amplifiers are described which treat both planar and helical wiggler geometries. For convenience, the authors refer to the planar (helical) formulation and simulation code as WIGGLIN (ARACHNE). These formulations are slow-time-scale models for FEL amplifiers in which the electron dynamics are treated using the complete 3-D Lorentz force equations without recourse to a wiggler period average. The application of these codes to the description of a collective reversed-field FEL experiment and to random wiggler field errors is described

  1. Radiobiological application of simulation of low-energy electron transport in liquid water

    International Nuclear Information System (INIS)

    Eudaldo Puell, Teresa.

    1979-01-01

    A Monte-Carlo transport simulation method, so-called event-after-event method provide results about trajectories of low-energy electrons, slowing-down in liquid water. A radiosensitive target model constituted by water cylindrical volumes, like the ones which surround the DNA molecule, is taken into consideration. The results characterizing the primary physical stage of radiation action, such as, space ionization distributions, interionization distance distributions ..., are obtained in some configurations constituted by single or several targets, in order to approach the biological reality [fr

  2. New exploration on TMSR: modelling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Si, S.; Chen, Q.; Bei, H.; Zhao, J., E-mail: ssy@snerdi.com.cn [Shanghai Nuclear Engineering Research & Design Inst., Shanghai (China)

    2015-07-01

    A tightly coupled multi-physics model for MSR (Molten Salt Reactor) system involving the reactor core and the rest of the primary loop has been developed and employed in an in-house developed computer code TANG-MSR. In this paper, the computer code is used to simulate the behavior of steady state operation and transient for our redesigned TMSR. The presented simulation results demonstrate that the models employed in TANG-MSR can capture major physics phenomena in MSR and the redesigned TMSR has excellent performance of safety and sustainability. (author)

  3. Analysis of operating model of electronic invoice colombian Colombian electronic billing analysis of the operational model

    Directory of Open Access Journals (Sweden)

    Sérgio Roberto da Silva

    2016-06-01

    Full Text Available Colombia has been one of the first countries to introduce electronic billing process on a voluntary basis, from a traditional to a digital version. In this context, the article analyzes the electronic billing process implemented in Colombia and the advantages. Methodological research is applied, qualitative, descriptive and documentary; where the regulatory framework and the conceptualization of the model is identified; the process of adoption of electronic billing is analyzed, and finally the advantages and disadvantages of its implementation is analyzed. The findings indicate that the model applied in Colombia to issue an electronic billing in sending and receiving process, is not complex, but it requires a small adequate infrastructure and trained personnel to reach all sectors, especially the micro and business which is the largest business network in the country.

  4. A Simulation Platform To Model, Optimize And Design Wind Turbines. The Matlab/Simulink Toolbox

    Directory of Open Access Journals (Sweden)

    Anca Daniela HANSEN

    2002-12-01

    Full Text Available In the last years Matlab / Simulink® has become the most used software for modeling and simulation of dynamic systems. Wind energy conversion systems are for example such systems, containing subsystems with different ranges of the time constants: wind, turbine, generator, power electronics, transformer and grid. The electrical generator and the power converter need the smallest simulation step and therefore, these blocks decide the simulation speed. This paper presents a new and integrated simulation platform for modeling, optimizing and designing wind turbines. The platform contains different simulation tools: Matlab / Simulink - used as basic modeling tool, HAWC, DIgSilent and Saber.

  5. Nuclear reactor core modelling in multifunctional simulators

    International Nuclear Information System (INIS)

    Puska, E.K.

    1999-01-01

    The thesis concentrates on the development of nuclear reactor core models for the APROS multifunctional simulation environment and the use of the core models in various kinds of applications. The work was started in 1986 as a part of the development of the entire APROS simulation system. The aim was to create core models that would serve in a reliable manner in an interactive, modular and multifunctional simulator/plant analyser environment. One-dimensional and three-dimensional core neutronics models have been developed. Both models have two energy groups and six delayed neutron groups. The three-dimensional finite difference type core model is able to describe both BWR- and PWR-type cores with quadratic fuel assemblies and VVER-type cores with hexagonal fuel assemblies. The one- and three-dimensional core neutronics models can be connected with the homogeneous, the five-equation or the six-equation thermal hydraulic models of APROS. The key feature of APROS is that the same physical models can be used in various applications. The nuclear reactor core models of APROS have been built in such a manner that the same models can be used in simulator and plant analyser applications, as well as in safety analysis. In the APROS environment the user can select the number of flow channels in the three-dimensional reactor core and either the homogeneous, the five- or the six-equation thermal hydraulic model for these channels. The thermal hydraulic model and the number of flow channels have a decisive effect on the calculation time of the three-dimensional core model and thus, at present, these particular selections make the major difference between a safety analysis core model and a training simulator core model. The emphasis on this thesis is on the three-dimensional core model and its capability to analyse symmetric and asymmetric events in the core. The factors affecting the calculation times of various three-dimensional BWR, PWR and WWER-type APROS core models have been

  6. Nuclear reactor core modelling in multifunctional simulators

    Energy Technology Data Exchange (ETDEWEB)

    Puska, E.K. [VTT Energy, Nuclear Energy, Espoo (Finland)

    1999-06-01

    The thesis concentrates on the development of nuclear reactor core models for the APROS multifunctional simulation environment and the use of the core models in various kinds of applications. The work was started in 1986 as a part of the development of the entire APROS simulation system. The aim was to create core models that would serve in a reliable manner in an interactive, modular and multifunctional simulator/plant analyser environment. One-dimensional and three-dimensional core neutronics models have been developed. Both models have two energy groups and six delayed neutron groups. The three-dimensional finite difference type core model is able to describe both BWR- and PWR-type cores with quadratic fuel assemblies and VVER-type cores with hexagonal fuel assemblies. The one- and three-dimensional core neutronics models can be connected with the homogeneous, the five-equation or the six-equation thermal hydraulic models of APROS. The key feature of APROS is that the same physical models can be used in various applications. The nuclear reactor core models of APROS have been built in such a manner that the same models can be used in simulator and plant analyser applications, as well as in safety analysis. In the APROS environment the user can select the number of flow channels in the three-dimensional reactor core and either the homogeneous, the five- or the six-equation thermal hydraulic model for these channels. The thermal hydraulic model and the number of flow channels have a decisive effect on the calculation time of the three-dimensional core model and thus, at present, these particular selections make the major difference between a safety analysis core model and a training simulator core model. The emphasis on this thesis is on the three-dimensional core model and its capability to analyse symmetric and asymmetric events in the core. The factors affecting the calculation times of various three-dimensional BWR, PWR and WWER-type APROS core models have been

  7. New simulation capabilities of electron clouds in ion beams with large tune depression

    International Nuclear Information System (INIS)

    Vay, J.-L.; Furman, M.A.; Seidl, P.A.

    2007-01-01

    We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D 'slice' e-cloud code POSINST [M. Furman, this workshop, paper TUAX05], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new 'drift-Lorentz' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop, paper THAW02]. We describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC). (author)

  8. New simulation capabilities of electron clouds in ion beams with large tune depression

    International Nuclear Information System (INIS)

    Lawrence Livermore National Laboratory

    2006-01-01

    We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D ''slice'' e-cloud code POSINST [M. Furman, this workshop, paper TUAX05], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new ''drift-Lorentz'' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop, paper THAW02]. We describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC)

  9. New simulation capabilities of electron clouds in ion beams with large tune depression

    International Nuclear Information System (INIS)

    Vay, J.L.; Furman, M.A.; Seidl, P.A.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Kireeff-Covo, M.; Molvik, A.W.; Stoltz, P.H.; Veitzer, S.; Verboncoeur, J.P.

    2006-01-01

    The authors have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D ''slice'' e-cloud code POSINST, as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new ''drift-Lorentz'' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX). They describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC)

  10. First-principles electron dynamics control simulation of diamond under femtosecond laser pulse train irradiation

    International Nuclear Information System (INIS)

    Wang Cong; Jiang Lan; Wang Feng; Li Xin; Yuan Yanping; Xiao Hai; Tsai, Hai-Lung; Lu Yongfeng

    2012-01-01

    A real-time and real-space time-dependent density functional is applied to simulate the nonlinear electron-photon interactions during shaped femtosecond laser pulse train ablation of diamond. Effects of the key pulse train parameters such as the pulse separation, spatial/temporal pulse energy distribution and pulse number per train on the electron excitation and energy absorption are discussed. The calculations show that photon-electron interactions and transient localized electron dynamics can be controlled including photon absorption, electron excitation, electron density, and free electron distribution by the ultrafast laser pulse train. (paper)

  11. Modeling of the response under radiation of electronic dosemeters

    International Nuclear Information System (INIS)

    Menard, S.

    2003-01-01

    The simulation with with calculation codes the interactions and the transport of primary and secondary radiations in the detectors allows to reduce the number of developed prototypes and the number of experiments under radiation. The simulation makes possible the determination of the response of the instrument for exposure configurations more extended that these ones of references radiations produced in laboratories. The M.C.N.P.X. allows to transport, over the photons, electrons and neutrons, the charged particles heavier than the electrons and to simulate the radiation - matter interactions for a certain number of particles. The present paper aims to present the interest of the use of the M.C.N.P.X. code in the study, research and evaluation phases of the instrumentation necessary to the dosimetry monitoring. To do that the presentation gives the results of the modeling of a prototype of a equivalent tissue proportional counter (C.P.E.T.) and of the C.R.A.M.A.L. ( radiation protection apparatus marketed by the Eurisys Mesures society). (N.C.)

  12. Kanban simulation model for production process optimization

    Directory of Open Access Journals (Sweden)

    Golchev Riste

    2015-01-01

    Full Text Available A long time has passed since the KANBAN system has been established as an efficient method for coping with the excessive inventory. Still, the possibilities for its improvement through its integration with other different approaches should be investigated further. The basic research challenge of this paper is to present benefits of KANBAN implementation supported with Discrete Event Simulation (DES. In that direction, at the beginning, the basics of KANBAN system are presented with emphasis on the information and material flow, together with a methodology for implementation of KANBAN system. Certain analysis on combining the simulation with this methodology is presented. The paper is concluded with a practical example which shows that through understanding the philosophy of the implementation methodology of KANBAN system and the simulation methodology, a simulation model can be created which can serve as a basis for a variety of experiments that can be conducted within a short period of time, resulting with production process optimization.

  13. Vermont Yankee simulator BOP model upgrade

    International Nuclear Information System (INIS)

    Alejandro, R.; Udbinac, M.J.

    2006-01-01

    The Vermont Yankee simulator has undergone significant changes in the 20 years since the original order was placed. After the move from the original Unix to MS Windows environment, and upgrade to the latest version of SimPort, now called MASTER, the platform was set for an overhaul and replacement of major plant system models. Over a period of a few months, the VY simulator team, in partnership with WSC engineers, replaced outdated legacy models of the main steam, condenser, condensate, circulating water, feedwater and feedwater heaters, and main turbine and auxiliaries. The timing was ideal, as the plant was undergoing a power up-rate, so the opportunity was taken to replace the legacy models with industry-leading, true on-line object oriented graphical models. Due to the efficiency of design and ease of use of the MASTER tools, VY staff performed the majority of the modeling work themselves with great success, with only occasional assistance from WSC, in a relatively short time-period, despite having to maintain all of their 'regular' simulator maintenance responsibilities. This paper will provide a more detailed view of the VY simulator, including how it is used and how it has benefited from the enhancements and upgrades implemented during the project. (author)

  14. Second-principles method for materials simulations including electron and lattice degrees of freedom

    Science.gov (United States)

    García-Fernández, Pablo; Wojdeł, Jacek C.; Íñiguez, Jorge; Junquera, Javier

    2016-05-01

    We present a first-principles-based (second-principles) scheme that permits large-scale materials simulations including both atomic and electronic degrees of freedom on the same footing. The method is based on a predictive quantum-mechanical theory—e.g., density functional theory—and its accuracy can be systematically improved at a very modest computational cost. Our approach is based on dividing the electron density of the system into a reference part—typically corresponding to the system's neutral, geometry-dependent ground state—and a deformation part—defined as the difference between the actual and reference densities. We then take advantage of the fact that the bulk part of the system's energy depends on the reference density alone; this part can be efficiently and accurately described by a force field, thus avoiding explicit consideration of the electrons. Then, the effects associated to the difference density can be treated perturbatively with good precision by working in a suitably chosen Wannier function basis. Further, the electronic model can be restricted to the bands of interest. All these features combined yield a very flexible and computationally very efficient scheme. Here we present the basic formulation of this approach, as well as a practical strategy to compute model parameters for realistic materials. We illustrate the accuracy and scope of the proposed method with two case studies, namely, the relative stability of various spin arrangements in NiO (featuring complex magnetic interactions in a strongly-correlated oxide) and the formation of a two-dimensional electron gas at the interface between band insulators LaAlO3 and SrTiO3 (featuring subtle electron-lattice couplings and screening effects). We conclude by discussing ways to overcome the limitations of the present approach (most notably, the assumption of a fixed bonding topology), as well as its many envisioned possibilities and future extensions.

  15. Model of contamination sources of electron for radiotherapy of beams of photons

    International Nuclear Information System (INIS)

    Gonzalez Infantes, W.; Lallena Rojo, A. M.; Anguiano Millan, M.

    2013-01-01

    Proposes a model of virtual sources of electrons, that allows to reproduce the sources to the input parameters of the representation of the patient. To compare performance in depth values and calculated profiles from the full simulation of the heads, with the calculated values using sources model, found that the model is capable of playing depth dose distributions and profiles. (Author)

  16. MEGACELL: A nanocrystal model construction software for HRTEM multislice simulation

    International Nuclear Information System (INIS)

    Stroppa, Daniel G.; Righetto, Ricardo D.; Montoro, Luciano A.; Ramirez, Antonio J.

    2011-01-01

    Image simulation has an invaluable importance for the accurate analysis of High Resolution Transmission Electron Microscope (HRTEM) results, especially due to its non-linear image formation mechanism. Because the as-obtained images cannot be interpreted in a straightforward fashion, the retrieval of both qualitative and quantitative information from HRTEM micrographs requires an iterative process including the simulation of a nanocrystal model and its comparison with experimental images. However most of the available image simulation software requires atom-by-atom coordinates as input for the calculations, which can be prohibitive for large finite crystals and/or low-symmetry systems and zone axis orientations. This paper presents an open source citation-ware tool named MEGACELL, which was developed to assist on the construction of nanocrystals models. It allows the user to build nanocrystals with virtually any convex polyhedral geometry and to retrieve its atomic positions either as a plain text file or as an output compatible with EMS (Electron Microscopy Software) input protocol. In addition to the description of this tool features, some construction examples and its application for scientific studies are presented. These studies show MEGACELL as a handy tool, which allows an easier construction of complex nanocrystal models and improves the quantitative information extraction from HRTEM images. -- Highlights: → A software to support the HRTEM image simulation of nanocrystals in actual size. → MEGACELL allows the construction of complex nanocrystals models for multislice image simulation. → Some examples of improved nanocrystalline system characterization are presented, including the analysis of 3D morphology and growth behavior.

  17. Numerical simulation of electronic properties of coupled quantum dots on wetting layers

    International Nuclear Information System (INIS)

    Betcke, M M; Voss, H

    2008-01-01

    Self-assembled quantum dots are grown on wetting layers and frequently in an array-like assembly of many similar but not exactly equal dots. Nevertheless, most simulations disregard these structural conditions and restrict themselves to simulating a pure single quantum dot. For reasons of numerical efficiency we advocate the effective one-band Hamiltonian with energy- and position-dependent effective mass approximation and a finite height hard-wall 3D confinement potential for computation of the energy levels of the electrons in the conduction band. Within this model we investigate the geometrical effects mentioned above on the electronic structure of a pyramidal InAs quantum dot embedded in a GaAs matrix. We find that the presence of a wetting layer may affect the electronic structure noticeably. Furthermore, we establish that, in spite of the large bandgap of the InAs/GaAs heterostructure, if the dots in a vertically aligned array are sufficiently close stacked there is considerable interaction between their eigenfunctions. Moreover, the eigenfunctions of such an array are quite sensitive to certain structural perturbations

  18. Simulation of the interaction of positively charged beams and electron clouds

    International Nuclear Information System (INIS)

    Markovik, Aleksandar

    2013-01-01

    The incoherent (head-tail) effect on the bunch due to the interaction with electron clouds (e-clouds) leads to a blow up of the transverse beam size in storage rings operating with positively charged beams. Even more the e-cloud effects are considered to be the main limiting factor for high current, high-brightness or high-luminosity operation of future machines. Therefore the simulation of e-cloud phenomena is a highly active field of research. The main focus in this work was set to a development of a tool for simulation of the interaction of relativistic bunches with non-relativistic parasitic charged particles. The result is the Particle-In-Cell Program MOEVE PIC Tracking which can track a 3D bunch under the influence of its own and external electromagnetic fields but first and foremost it simulates the interaction of relativistic positively charged bunches and initially static electrons. In MOEVE PIC Tracking the conducting beam pipe can be modeled with an arbitrary elliptical cross-section to achieve more accurate space charge field computations for both the bunch and the e-cloud. The simulation of the interaction between positron bunches and electron clouds in this work gave a detailed insight of the behavior of both particle species during and after the interaction. Further and ultimate goal of this work was a fast estimation of the beam stability under the influence of e-clouds in the storage ring. The standard approach to simulate the stability of a single bunch is to track the bunch particles through the linear optics of the machine by multiplying the 6D vector of each particle with the transformation matrices describing the lattice. Thereby the action of the e-cloud on the bunch is approximated by a pre-computed wake kick which is applied on one or more points in the lattice. Following the idea of K.Ohmi the wake kick was pre-computed as a two variable function of the bunch part exiting the e-cloud and the subsequent parts of a bunch which receive a

  19. Molecular origin of differences in hole and electron mobility in amorphous Alq3--a multiscale simulation study.

    Science.gov (United States)

    Fuchs, Andreas; Steinbrecher, Thomas; Mommer, Mario S; Nagata, Yuki; Elstner, Marcus; Lennartz, Christian

    2012-03-28

    In order to determine the molecular origin of the difference in electron and hole mobilities of amorphous thin films of Alq(3) (meridional Alq(3) (tris(8-hydroxyquinoline) aluminium)) we performed multiscale simulations covering quantum mechanics, molecular mechanics and lattice models. The study includes realistic disordered morphologies, polarized site energies to describe diagonal disorder, quantum chemically calculated transfer integrals for the off-diagonal disorder, inner sphere reorganization energies and an approximative scheme for outer sphere reorganization energies. Intermolecular transfer rates were calculated via Marcus-theory and mobilities were simulated via kinetic Monte Carlo simulations and by a Master Equation approach. The difference in electron and hole mobility originates from the different localization of charge density in the radical anion (more delocalized) compared to the radical cation (more confined). This results in higher diagonal disorder for holes and less favourable overlap properties for the hole transfer integrals leading to an overall higher electron mobility.

  20. Numerical Simulation of Transient Moisture Transfer into an Electronic Enclosure

    DEFF Research Database (Denmark)

    Shojaee Nasirabadi, Parizad; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    Electronic systems are sometimes exposed to harsh environmental conditions of temperature and humidity. Moisturetransfer into electronic enclosures and condensation can cause several problems such as corrosion and alteration in thermalstresses. It is therefore essential to study the local climate...... inside the enclosures to be able to protect the electronic systems.In this work, moisture transfer into a typical electronic enclosure is numerically studied using CFD. In order to reduce theCPU-time and make a way for subsequent factorial design analysis, a simplifying modification is applied in which...

  1. The electronically excited states of LH2 complexes from Rhodopseudomonas acidophila strain 10050 studied by time-resolved spectroscopy and dynamic Monte Carlo simulations. II. Homo-arrays of LH2 complexes reconstituted into phospholipid model membranes.

    Science.gov (United States)

    Pflock, Tobias J; Oellerich, Silke; Krapf, Lisa; Southall, June; Cogdell, Richard J; Ullmann, G Matthias; Köhler, Jürgen

    2011-07-21

    We performed time-resolved spectroscopy on homoarrays of LH2 complexes from the photosynthetic purple bacterium Rhodopseudomonas acidophila. Variations of the fluorescence transients were monitored as a function of the excitation fluence and the repetition rate of the excitation. These parameters are directly related to the excitation density within the array and to the number of LH2 complexes that still carry a triplet state prior to the next excitation. Comparison of the experimental observations with results from dynamic Monte Carlo simulations for a model cluster of LH2 complexes yields qualitative agreement without the need for any free parameter and reveals the mutual relationship between energy transfer and annihilation processes.

  2. Simulation modeling and analysis in safety. II

    International Nuclear Information System (INIS)

    Ayoub, M.A.

    1981-01-01

    The paper introduces and illustrates simulation modeling as a viable approach for dealing with complex issues and decisions in safety and health. The author details two studies: evaluation of employee exposure to airborne radioactive materials and effectiveness of the safety organization. The first study seeks to define a policy to manage a facility used in testing employees for radiation contamination. An acceptable policy is one that would permit the testing of all employees as defined under regulatory requirements, while not exceeding available resources. The second study evaluates the relationship between safety performance and the characteristics of the organization, its management, its policy, and communication patterns among various functions and levels. Both studies use models where decisions are reached based on the prevailing conditions and occurrence of key events within the simulation environment. Finally, several problem areas suitable for simulation studies are highlighted. (Auth.)

  3. Modeling salmonella Dublin into the dairy herd simulation model Simherd

    DEFF Research Database (Denmark)

    Kudahl, Anne Braad

    2010-01-01

    Infection with Salmonella Dublin in the dairy herd and effects of the infection and relevant control measures are currently being modeled into the dairy herd simulation model called Simherd. The aim is to compare the effects of different control strategies against Salmonella Dublin on both within...... of the simulations will therefore be used for decision support in the national surveillance and eradication program against Salmonella Dublin. Basic structures of the model are programmed and will be presented at the workshop. The model is in a phase of face-validation by a group of Salmonella......-herd- prevalence and economy by simulations. The project Dublin on both within-herd- prevalence and economy by simulations. The project is a part of a larger national project "Salmonella 2007 - 2011" with the main objective to reduce the prevalence of Salmonella Dublin in Danish Dairy herds. Results...

  4. Imitating model of the electronic regulator frequencies of rotation of the automobile diesel engine

    OpenAIRE

    Тырловой, С. И.

    2011-01-01

    The imitating model of an frequency electronic regulator of rotation of high-speed diesel engine an automobile diesel engine with the distributive fuel pump of Bosch company is resulted. Is executed simulation transitive modes of a diesel engine with mechanic and electronic regulators. Deterioration influence plungers steams on dinamic and economic indicators of a diesel engine is analysed. Operational indicators of a diesel engine with mechanic and electronic regulators are compared. The obt...

  5. Numerical simulation of runaway electron effect on Plasma Facing Components

    International Nuclear Information System (INIS)

    Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato; Kunugi, Tomoaki

    1998-07-01

    The runaway electron effects on Plasma Facing Components (PFCs) are studied by the numerical analyses. The present study is the first investigation of time-dependent thermal response of PFCs caused by runaway electron impact. For this purpose, we developed a new integrated numerical code, which consists of the Monte Carlo code for the coupled electrons and photons transport analysis and the finite element code for the thermo-mechanical analysis. In this code, we apply the practical incident parameters and distribution of runaway electrons recently proposed by S. Putvinski, which can express the time-dependent behavior of runaway electrons impact. The incident parameters of electrons in this study are the energy density ranging from 10 to 75 MJ/m 2 , the average electrons' energy of 12.5 MeV, the incident angle of 0.01deg and the characteristic time constant for decay of runaway electrons event of 0.15sec. The numerical results showed that the divertor with CFC (Carbon-Fiber-Composite) armor did not suffer serious damage. On the other hand, maximum temperatures at the surface of the divertor with tungsten armor and the first wall with beryllium armor exceed the melting point in case of the incident energy density of 20 and 50 MJ/m 2 . Within the range of the incident condition of runaway electrons, the cooling pipe of each PFCs can be prevented from the melting or burn-out caused by runaway electrons impact, which is one of the possible consequences of runaway electrons event so far. (author)

  6. Theory, Modeling and Simulation: Research progress report 1994--1995

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, B.C.; Dixon, D.A.; Dunning, T.H.

    1997-01-01

    The Pacific Northwest National Laboratory (PNNL) has established the Environmental Molecular Sciences Laboratory (EMSL). In April 1994, construction began on the new EMSL, a collaborative research facility devoted to advancing the understanding of environmental molecular science. Research in the Theory, Modeling, and Simulation (TM and S) program will play a critical role in understanding molecular processes important in restoring DOE`s research, development, and production sites, including understanding the migration and reactions of contaminants in soils and ground water, developing processes for isolation and processing of pollutants, developing improved materials for waste storage, understanding the enzymatic reactions involved in the biodegradation of contaminants, and understanding the interaction of hazardous chemicals with living organisms. The research objectives of the TM and S program are fivefold: to apply available electronic structure and dynamics techniques to study fundamental molecular processes involved in the chemistry of natural and contaminated systems; to extend current electronic structure and dynamics techniques to treat molecular systems of future importance and to develop new techniques for addressing problems that are computationally intractable at present; to apply available molecular modeling techniques to simulate molecular processes occurring in the multi-species, multi-phase systems characteristic of natural and polluted environments; to extend current molecular modeling techniques to treat ever more complex molecular systems and to improve the reliability and accuracy of such simulations; and to develop technologies for advanced parallel architectural computer systems. Research highlights of 82 projects are given.

  7. A universal simulator for ecological models

    DEFF Research Database (Denmark)

    Holst, Niels

    2013-01-01

    Software design is an often neglected issue in ecological models, even though bad software design often becomes a hindrance for re-using, sharing and even grasping an ecological model. In this paper, the methodology of agile software design was applied to the domain of ecological models. Thus...... the principles for a universal design of ecological models were arrived at. To exemplify this design, the open-source software Universal Simulator was constructed using C++ and XML and is provided as a resource for inspiration....

  8. Biological transportation networks: Modeling and simulation

    KAUST Repository

    Albi, Giacomo

    2015-09-15

    We present a model for biological network formation originally introduced by Cai and Hu [Adaptation and optimization of biological transport networks, Phys. Rev. Lett. 111 (2013) 138701]. The modeling of fluid transportation (e.g., leaf venation and angiogenesis) and ion transportation networks (e.g., neural networks) is explained in detail and basic analytical features like the gradient flow structure of the fluid transportation network model and the impact of the model parameters on the geometry and topology of network formation are analyzed. We also present a numerical finite-element based discretization scheme and discuss sample cases of network formation simulations.

  9. Reproducibility in Computational Neuroscience Models and Simulations

    Science.gov (United States)

    McDougal, Robert A.; Bulanova, Anna S.; Lytton, William W.

    2016-01-01

    Objective Like all scientific research, computational neuroscience research must be reproducible. Big data science, including simulation research, cannot depend exclusively on journal articles as the method to provide the sharing and transparency required for reproducibility. Methods Ensuring model reproducibility requires the use of multiple standard software practices and tools, including version control, strong commenting and documentation, and code modularity. Results Building on these standard practices, model sharing sites and tools have been developed that fit into several categories: 1. standardized neural simulators, 2. shared computational resources, 3. declarative model descriptors, ontologies and standardized annotations; 4. model sharing repositories and sharing standards. Conclusion A number of complementary innovations have been proposed to enhance sharing, transparency and reproducibility. The individual user can be encouraged to make use of version control, commenting, documentation and modularity in development of models. The community can help by requiring model sharing as a condition of publication and funding. Significance Model management will become increasingly important as multiscale models become larger, more detailed and correspondingly more difficult to manage by any single investigator or single laboratory. Additional big data management complexity will come as the models become more useful in interpreting experiments, thus increasing the need to ensure clear alignment between modeling data, both parameters and results, and experiment. PMID:27046845

  10. A SIMULATION MODEL OF THE GAS COMPLEX

    Directory of Open Access Journals (Sweden)

    Sokolova G. E.

    2016-06-01

    Full Text Available The article considers the dynamics of gas production in Russia, the structure of sales in the different market segments, as well as comparative dynamics of selling prices on these segments. Problems of approach to the creation of the gas complex using a simulation model, allowing to estimate efficiency of the project and determine the stability region of the obtained solutions. In the presented model takes into account the unit repayment of the loan, allowing with the first year of simulation to determine the possibility of repayment of the loan. The model object is a group of gas fields, which is determined by the minimum flow rate above which the project is cost-effective. In determining the minimum source flow rate for the norm of discount is taken as a generalized weighted average percentage on debt and equity taking into account risk premiums. He also serves as the lower barrier to internal rate of return below which the project is rejected as ineffective. Analysis of the dynamics and methods of expert evaluation allow to determine the intervals of variation of the simulated parameters, such as the price of gas and the exit gas complex at projected capacity. Calculated using the Monte Carlo method, for each random realization of the model simulated values of parameters allow to obtain a set of optimal for each realization of values minimum yield of wells, and also allows to determine the stability region of the solution.

  11. Object Oriented Modelling and Dynamical Simulation

    DEFF Research Database (Denmark)

    Wagner, Falko Jens; Poulsen, Mikael Zebbelin

    1998-01-01

    This report with appendix describes the work done in master project at DTU.The goal of the project was to develop a concept for simulation of dynamical systems based on object oriented methods.The result was a library of C++-classes, for use when both building componentbased models and when...

  12. Advanced feeder control using fast simulation models

    NARCIS (Netherlands)

    Verheijen, O.S.; Op den Camp, O.M.G.C.; Beerkens, R.G.C.; Backx, A.C.P.M.; Huisman, L.; Drummond, C.H.

    2005-01-01

    For the automatic control of glass quality in glass production, the relation between process variable and product or glass quality and process conditions/process input parameters must be known in detail. So far, detailed 3-D glass melting simulation models were used to predict the effect of process

  13. Modeling and Simulating Virtual Anatomical Humans

    NARCIS (Netherlands)

    Madehkhaksar, Forough; Luo, Zhiping; Pronost, Nicolas; Egges, Arjan

    2014-01-01

    This chapter presents human musculoskeletal modeling and simulation as a challenging field that lies between biomechanics and computer animation. One of the main goals of computer animation research is to develop algorithms and systems that produce plausible motion. On the other hand, the main

  14. Agent Based Modelling for Social Simulation

    NARCIS (Netherlands)

    Smit, S.K.; Ubink, E.M.; Vecht, B. van der; Langley, D.J.

    2013-01-01

    This document is the result of an exploratory project looking into the status of, and opportunities for Agent Based Modelling (ABM) at TNO. The project focussed on ABM applications containing social interactions and human factors, which we termed ABM for social simulation (ABM4SS). During the course

  15. Thermohydraulic modeling and simulation of breeder reactors

    International Nuclear Information System (INIS)

    Agrawal, A.K.; Khatib-Rahbar, M.; Curtis, R.T.; Hetrick, D.L.; Girijashankar, P.V.

    1982-01-01

    This paper deals with the modeling and simulation of system-wide transients in LMFBRs. Unprotected events (i.e., the presumption of failure of the plant protection system) leading to core-melt are not considered in this paper. The existing computational capabilities in the area of protected transients in the US are noted. Various physical and numerical approximations that are made in these codes are discussed. Finally, the future direction in the area of model verification and improvements is discussed

  16. Simulation and Optimization of a Carbon Nanotube Electron Source

    Czech Academy of Sciences Publication Activity Database

    Knápek, Alexandr; Radlička, Tomáš; Krátký, Stanislav

    2015-01-01

    Roč. 21, S4 (2015), s. 60-65 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : carbon nanotube * electron beam lithography Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  17. Simulation of long-term dynamic behavior of runaway electrons

    International Nuclear Information System (INIS)

    Wang Yulei; Liu Jian; Zhang Ruili; He Yang

    2015-01-01

    The secular dynamics of runaway electrons in Tokamak electromagnetic field is studied. The radiation effect is added into a relativistic volume-preserving algorithm to gain long-term stability of calculation. The results shows that the method we used is able to reveal the behavior of a runaway electron in configuration space. (author)

  18. Model based design of electronic throttle control

    Science.gov (United States)

    Cherian, Fenin; Ranjan, Ashish; Bhowmick, Pathikrit; Rammohan, A.

    2017-11-01

    With the advent of torque based Engine Management Systems, the precise control and robust performance of the throttle body becomes a key factor in the overall performance of the vehicle. Electronic Throttle Control provides benefits such as improved air-fuel ratio for improving the vehicle performance and lower exhausts emissions to meet the stringent emission norms. Modern vehicles facilitate various features such as Cruise Control, Traction Control, Electronic Stability Program and Pre-crash systems. These systems require control over engine power without driver intervention, which is not possible with conventional mechanical throttle system. Thus these systems are integrated to function with the electronic throttle control. However, due to inherent non-linearities in the throttle body, the control becomes a difficult task. In order to eliminate the influence of this hysteresis at the initial operation of the butterfly valve, a control to compensate the shortage must be added to the duty required for starting throttle operation when the initial operation is detected. Therefore, a lot of work is being done in this field to incorporate the various nonlinearities to achieve robust control. In our present work, the ETB was tested to verify the working of the system. Calibration of the TPS sensors was carried out in order to acquire accurate throttle opening angle. The response of the calibrated system was then plotted against a step input signal. A linear model of the ETB was prepared using Simulink and its response was compared with the experimental data to find out the initial deviation of the model from the actual system. To reduce this deviation, non-linearities from existing literature were introduced to the system and a response analysis was performed to check the deviation from the actual system. Based on this investigation, an introduction of a new nonlinearity parameter can be used in future to reduce the deviation further making the control of the ETB more

  19. Simulated annealing method for electronic circuits design: adaptation and comparison with other optimization methods

    International Nuclear Information System (INIS)

    Berthiau, G.

    1995-10-01

    The circuit design problem consists in determining acceptable parameter values (resistors, capacitors, transistors geometries ...) which allow the circuit to meet various user given operational criteria (DC consumption, AC bandwidth, transient times ...). This task is equivalent to a multidimensional and/or multi objective optimization problem: n-variables functions have to be minimized in an hyper-rectangular domain ; equality constraints can be eventually specified. A similar problem consists in fitting component models. In this way, the optimization variables are the model parameters and one aims at minimizing a cost function built on the error between the model response and the data measured on the component. The chosen optimization method for this kind of problem is the simulated annealing method. This method, provided by the combinatorial optimization domain, has been adapted and compared with other global optimization methods for the continuous variables problems. An efficient strategy of variables discretization and a set of complementary stopping criteria have been proposed. The different parameters of the method have been adjusted with analytical functions of which minima are known, classically used in the literature. Our simulated annealing algorithm has been coupled with an open electrical simulator SPICE-PAC of which the modular structure allows the chaining of simulations required by the circuit optimization process. We proposed, for high-dimensional problems, a partitioning technique which ensures proportionality between CPU-time and variables number. To compare our method with others, we have adapted three other methods coming from combinatorial optimization domain - the threshold method, a genetic algorithm and the Tabu search method - The tests have been performed on the same set of test functions and the results allow a first comparison between these methods applied to continuous optimization variables. Finally, our simulated annealing program

  20. Simulation model for studying low frequency microinstabilities

    International Nuclear Information System (INIS)

    Lee, W.W.; Okuda, H.

    1976-03-01

    A 2 1 / 2 dimensional, electrostatic particle code in a slab geometry has been developed to study low frequency oscillations such as drift wave and trapped particle instabilities in a nonuniform bounded plasma. A drift approximation for the electron transverse motion is made which eliminates the high frequency oscillations at the electron gyrofrequency and its multiples. It is, therefore, possible to study the nonlinear effects such as the anomalous transport of plasmas within a reasonable computing time using a real mass ratio. Several examples are given to check the validity and usefulness of the model