Science.gov

Sample records for hysdrodynamic lattice-gas simulations

  1. Lattice gas simulations of dynamical geometry in two dimensions

    NASA Astrophysics Data System (ADS)

    Klales, Anna; Cianci, Donato; Needell, Zachary; Meyer, David A.; Love, Peter J.

    2010-10-01

    We present a hydrodynamic lattice gas model for two-dimensional flows on curved surfaces with dynamical geometry. This model is an extension to two dimensions of the dynamical geometry lattice gas model previously studied in one dimension. We expand upon a variation of the two-dimensional flat space Frisch-Hasslacher-Pomeau (FHP) model created by Frisch [Phys. Rev. Lett.PRLTAO0031-9007 56, 1505 (1986)]10.1103/PhysRevLett.56.1505 and independently by Wolfram, and modified by Boghosian [Philos. Trans. R. Soc. London, Ser. A 360, 333 (2002)]10.1098/rsta.2001.0933. We define a hydrodynamic lattice gas model on an arbitrary triangulation whose flat space limit is the FHP model. Rules that change the geometry are constructed using the Pachner moves, which alter the triangulation but not the topology. We present results on the growth of the number of triangles as a function of time. Simulations show that the number of triangles grows with time as t1/3 , in agreement with a mean-field prediction. We also present preliminary results on the distribution of curvature for a typical triangulation in these simulations.

  2. Overview: Understanding nucleation phenomena from simulations of lattice gas models

    NASA Astrophysics Data System (ADS)

    Binder, Kurt; Virnau, Peter

    2016-12-01

    Monte Carlo simulations of homogeneous and heterogeneous nucleation in Ising/lattice gas models are reviewed with an emphasis on the general insight gained on the mechanisms by which metastable states decay. Attention is paid to the proper distinction of particles that belong to a cluster (droplet), that may trigger a nucleation event, from particles in its environment, a problem crucial near the critical point. Well below the critical point, the lattice structure causes an anisotropy of the interface tension, and hence nonspherical droplet shapes result, making the treatment nontrivial even within the conventional classical theory of homogeneous nucleation. For temperatures below the roughening transition temperature facetted crystals rather than spherical droplets result. The possibility to find nucleation barriers from a thermodynamic analysis avoiding a cluster identification on the particle level is discussed, as well as the question of curvature corrections to the interfacial tension. For the interpretation of heterogeneous nucleation at planar walls, knowledge of contact angles and line tensions is desirable, and methods to extract these quantities from simulations will be mentioned. Finally, also the problem of nucleation near the stability limit of metastable states and the significance of the spinodal curve will be discussed, in the light of simulations of Ising models with medium range interactions.

  3. Lattice gas hydrodynamics of one and two-phase fluids in two and three dimensions: Theory and simulation

    SciTech Connect

    Diemer, K.L.

    1992-01-01

    Lattice gas automata models for hydrodynamics offer a method for simulating fluids in between the standard molecular dynamic models and finite difference schemes. The algorithm is especially suited to low Mach number flow around complex boundaries and can be implemented in a fully parallelizable, memory efficient manner using only boolean operations. The simplest lattice gas automata is reviewed. The modification of the standard Chapmann-Enskog expansion lattice gas case is reviewed. In the long wavelength and long time limit, the incompressible Navier-Stokes equation is derived. Analytic calculations of shear viscosity [eta], mean free path [lambda], and a reduced Reynolds number R are presented for a number of 2D and 3D lattice gas models. Comparisons of lattice gas results with analytical predictions and other numerical methods are reviewed. This is followed by a discussion of the zero velocity limit used in deriving the above analytic results. Lattice gas hydrodynamic models for flows through porous media in two and three dimensions are described. The computational method easily handles arbitrary boundaries and a large range of Reynolds numbers. Darcy's law is confirmed for Poiseuille flow and for complicated boundary flows. Lattice gas simulation results for permeability for one geometry are compared with experimental results and found to agree to within 10%. Lattice gas hydrodynamic models for two dimensional binary fluids are described. The scaling of the correlation function during late stage growth is examined. The domain growth kinetics during this period is also explored and compared with the work of Furukawa. A local lattice gas model for binary fluids with an adjustable parameter [lambda] which allows degree of miscibility is introduced. For [lambda] < [lambda][sub c] the fluids are immiscible while for [lambda] > [lambda][sub c] the fluids are miscible. Theoretical and numerical studies on the diffusive properties of this lattice gas are presented.

  4. Simulation of two-phase flow using lattice gas automata methods

    SciTech Connect

    Tsumaya, Akira; Ohashi, Hirotada; Akiyama, Mamoru

    1996-08-01

    Two-phase flow simulation has been primarily based on experimental data in the sense that constitutive relations necessary for solving fundamental equations are experimentally determined. This assures validity of simulation of two-phase flow within the experimental conditions, but it is difficult to predict the behavior of two-phase flow under extreme or complex conditions which occur, for example, in severe accidents of nuclear reactors. Lattice gas automaton (LGA) simulation has recently attracted attention as a method for numerical simulation of multi phase flow. The authors extend phase-separation LGA models and develop methods for two-phase flow simulation. First, they newly added a flow model to the immiscible lattice gas model and applied it to two-dimensional Poiseuille flow. They obtained a result looking like lubricated pipelining of crude oil with water. Also, considering the gravity effect, they introduced a buoyancy force into the liquid-gas model. As a result, they demonstrated that gas bubbles of various diameters rise and gradually coalesce each other turning into larger bubbles. Using these newly developed LGA models, they succeeded in simulating various flow patterns of two-phase flow.

  5. Pair interaction lattice gas simulations: Flow past obstacles in two and three dimensions

    SciTech Connect

    Vogeler, A.; Wolf-Gladrow, D.A. )

    1993-04-01

    Apart from the FCHC (face-centered hypercube), Nasilowski's pair interaction lattice gas (PI) is the only known lattice gas automaton for three-dimensional hydrodynamic simulations. Unfortunately, the viscosity of PI is not isotropic. In order to determine the degree anisotropy, the authors derive fluid dynamic equations for the regime of compressible viscid flow. From relaxation measurements of waves propagating in various directions they compute the physically relevant dissipation coefficients and compare their results with theoretical predictions. Although PI shows a high degree of anisotropy, they define the mean value of the dissipation tensor as effective shear viscosity. Using this value of v[sub eff][sup 2D] = 0.35, two-dimensional simulations of flow past a cylinder yield drag coefficients in quantitative agreement with wind tunnel measurements over a range of Reynolds numbers of 5-50. Three-dimensional simulations of flow past a sphere yield qualitative agreement with various references. A fit of the results to a semi-empirical curve provides an effective value of v[sub eff][sup 2D] = 0.21 for a range of Reynolds numbers from 0.19 to 40. In order to check for finite-size effects, the authors measured the mean free path [lambda] and computed the Knudsen numbers. They obtained [lambda] [approx]1 lattice unit, corresponding to Kn = 0.01 (2D) and Kn = 0.1 (3D). They found no significant finite-size effects. 44 refs., 10 figs.

  6. Simulating the time-dependent Schr"odinger equation with a quantum lattice-gas algorithm

    NASA Astrophysics Data System (ADS)

    Prezkuta, Zachary; Coffey, Mark

    2007-03-01

    Quantum computing algorithms promise remarkable improvements in speed or memory for certain applications. Currently, the Type II (or hybrid) quantum computer is the most feasible to build. This consists of a large number of small Type I (pure) quantum computers that compute with quantum logic, but communicate with nearest neighbors in a classical way. The arrangement thus formed is suitable for computations that execute a quantum lattice gas algorithm (QLGA). We report QLGA simulations for both the linear and nonlinear time-dependent Schr"odinger equation. These evidence the stable, efficient, and at least second order convergent properties of the algorithm. The simulation capability provides a computational tool for applications in nonlinear optics, superconducting and superfluid materials, Bose-Einstein condensates, and elsewhere.

  7. ``SAFFMAN-TAYLOR'' Finger in 2d Parallel Viscous: BGK Lattice Gas Simulations

    NASA Astrophysics Data System (ADS)

    Salin, Dominique; Rakotomalala, Nicole; Watzky, Philippe

    1996-11-01

    We study the displacement of miscible fluids between two parallel plates for different values of the Peclet number Pe and of the viscosity ratio M. The full Navier-Stokes problem is addressed. We use the BGK lattice gas method, which is well suited for miscible fluids and allows to introduce molecular diffusion at the microscopic scale of the lattice. This numerical experiment leads to a symmetric concentration profile about the middle of the gap between the plates. At Pe numbers of the order of 1, mixing involves diffusion and advection in the flow direction. At large Pe, the fluids do not mix and an interface between them can be defined. Moreover, above M ~ 10, the interface becomes a well defined finger, the reduced width of which tends to λ_∞=0.56 at large values of M. Assuming that miscible fluids at high Pe numbers are similar to immiscible fluids at high capillary numbers, we find the analytical shape of the finger, using an extrapolation of the Reinelt-Saffman calculations for a Stokes immiscible flow. Surprisingly, the result is that our finger can be deduced from the celebrated Saffman-Taylor' s one, obtained in a potential flow, by a streching in the flow direction by a numerical factor of 2.125.

  8. Counting Lattice-Gas Invariants

    DTIC Science & Technology

    2007-11-02

    Dominique d’Humières, Brosl Hasslacher, Pierre Lallemand, Yves Pomeau, and Jean-Pierre Rivet . Lattice gas hydrodynamics in two and three dimensions...177. Springer -Verlag, Februrary 1989. Proceedings of the Winter School, Les Houches, France. 6

  9. A non-thermal lattice gas model for a dimer trimer reaction on a catalytic surface: A computer simulation study

    NASA Astrophysics Data System (ADS)

    Ahmad, Waqar; Parvez, M.; Baloach, Musa Kaleem; Qaisrani, A. U.; Khalid, M.

    2006-11-01

    The kinetics of an irreversible dimer-trimer reaction of the type 3A 2 + 2B 3 → 6AB have been studied using a non-thermal (precursor mechanism) model on a square as well as on a hexagonal lattice surface by Monte Carlo simulation. When the range of the precursors (A atoms) is increased, the model gives production rates (reactive window widths) that are quite large as compared with those for thermal (Langmuir-Hanshelwood mechanism) model. The phase diagrams qualitatively resemble with the standard ZGB model except that the continuous transition point is eliminated when the range of the precursors is extended up to the third nearest neighbourhood. The diffusion of A atoms on the surface as well as their desorption from the surface with a certain probability is also considered to see their effects on the reaction mechanism.

  10. Realistic multisite lattice-gas modeling and KMC simulation of catalytic surface reactions: Kinetics and multiscale spatial behavior for CO-oxidation on metal (1 0 0) surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Da-Jiang; Evans, James W.

    2013-12-01

    A realistic molecular-level description of catalytic reactions on single-crystal metal surfaces can be provided by stochastic multisite lattice-gas (msLG) models. This approach has general applicability, although in this report, we will focus on the example of CO-oxidation on the unreconstructed fcc metal (1 0 0) or M(1 0 0) surfaces of common catalyst metals M = Pd, Rh, Pt and Ir (i.e., avoiding regimes where Pt and Ir reconstruct). These models can capture the thermodynamics and kinetics of adsorbed layers for the individual reactants species, such as CO/M(1 0 0) and O/M(1 0 0), as well as the interaction and reaction between different reactant species in mixed adlayers, such as (CO + O)/M(1 0 0). The msLG models allow population of any of hollow, bridge, and top sites. This enables a more flexible and realistic description of adsorption and adlayer ordering, as well as of reaction configurations and configuration-dependent barriers. Adspecies adsorption and interaction energies, as well as barriers for various processes, constitute key model input. The choice of these energies is guided by experimental observations, as well as by extensive Density Functional Theory analysis. Model behavior is assessed via Kinetic Monte Carlo (KMC) simulation. We also address the simulation challenges and theoretical ramifications associated with very rapid diffusion and local equilibration of reactant adspecies such as CO. These msLG models are applied to describe adsorption, ordering, and temperature programmed desorption (TPD) for individual CO/M(1 0 0) and O/M(1 0 0) reactant adlayers. In addition, they are also applied to predict mixed (CO + O)/M(1 0 0) adlayer structure on the nanoscale, the complete bifurcation diagram for reactive steady-states under continuous flow conditions, temperature programmed reaction (TPR) spectra, and titration reactions for the CO-oxidation reaction. Extensive and reasonably successful comparison of model predictions is made with experimental

  11. Lattice gas hydrodynamics in two and three dimensions

    SciTech Connect

    Frisch, U.; d'Humieres, D.; Hasslacher, B.; Lallemand, P.; Pomeau, Y.; Rivet, J.P.

    1986-01-01

    Hydrodynamical phenomena can be simulated by discrete lattice gas models obeing cellular automata rules (U. Frisch, B. Hasslacher, and Y. Pomeau, Phys. Rev. Lett. 56, 1505, (1986); D. d'Humieres, P. Lallemand, and U. Frisch, Europhys. Lett. 2, 291, (1986)). It is here shown for a class of D-dimensional lattice gas models how the macrodynamical (large-scale) equations for the densities of microscopically conserved quantities can be systematically derived from the underlying exact ''microdynamical'' Boolean equations. With suitable restrictions on the crystallographic symmetries of the lattice and after proper limits are taken, various standard fluid dynamical equations are obtained, including the incompressible Navier-Stokes equations in two and three dimensions. The transport coefficients appearing in the macrodynamical equations are obtained using variants of fluctuation-dissipation and Boltzmann formalisms adapted to fully discrete situations.

  12. Measurement-based quantum lattice gas model of fluid dynamics in 2+1 dimensions.

    PubMed

    Micci, Michael M; Yepez, Jeffrey

    2015-09-01

    Presented are quantum simulation results using a measurement-based quantum lattice gas algorithm for Navier-Stokes fluid dynamics in 2+1 dimensions. Numerical prediction of the kinematic viscosity was measured by the decay rate of an initial sinusoidal flow profile. Due to local quantum entanglement in the quantum lattice gas, the minimum kinematic viscosity in the measurement-based quantum lattice gas is lower than achievable in a classical lattice gas. The numerically predicted viscosities precisely match the theoretical predictions obtained with a mean field approximation. Uniform flow profile with double shear layers, on a 16K×8K lattice, leads to the Kelvin-Helmholtz instability, breaking up the shear layer into pairs of counter-rotating vortices that eventually merge via vortex fusion and dissipate because of the nonzero shear viscosity.

  13. An Overview of Lattice-Gas Dynamics

    DTIC Science & Technology

    1997-11-01

    irreversible. There- fore, the CAM-8 dissipates heat like any conventional computer even though the Szilard entropy of the lattice gas is unchanged, but an...Reviews of Modern Physics, 49(3):435–479, 1977. [37] Leo P. Kadanoff and Jack Swift. Transport coefficients near the critical point: A master-equation

  14. Lattice gas models with long range interactions

    NASA Astrophysics Data System (ADS)

    Aristoff, David; Zhu, Lingjiong

    2017-02-01

    We study microcanonical lattice gas models with long range interactions, including power law interactions. We rigorously obtain a variational principle for the entropy. In a one dimensional example, we find a first order phase transition by proving the entropy is non-differentiable along a certain curve.

  15. Multisite Interactions in Lattice-Gas Models

    NASA Astrophysics Data System (ADS)

    Einstein, T. L.; Sathiyanarayanan, R.

    For detailed applications of lattice-gas models to surface systems, multisite interactions often play at least as significant a role as interactions between pairs of adatoms that are separated by a few lattice spacings. We recall that trio (3-adatom, non-pairwise) interactions do not inevitably create phase boundary asymmetries about half coverage. We discuss a sophisticated application to an experimental system and describe refinements in extracting lattice-gas energies from calculations of total energies of several different ordered overlayers. We describe how lateral relaxations complicate matters when there is direct interaction between the adatoms, an issue that is important when examining the angular dependence of step line tensions. We discuss the connector model as an alternative viewpoint and close with a brief account of recent work on organic molecule overlayers.

  16. Dynamics of capillary condensation in lattice gas models of confined fluids: a comparison of dynamic mean field theory with dynamic Monte Carlo simulations.

    PubMed

    Edison, John R; Monson, Peter A

    2013-06-21

    This article addresses the accuracy of a dynamic mean field theory (DMFT) for fluids in porous materials [P. A. Monson, J. Chem. Phys. 128, 084701 (2008)]. The theory is used to study the relaxation processes of fluids in pores driven by step changes made to a bulk reservoir in contact with the pore. We compare the results of the DMFT to those obtained by averaging over large numbers of dynamic Monte Carlo (DMC) simulation trajectories. The problem chosen for comparison is capillary condensation in slit pores, driven by step changes in the chemical potential in the bulk reservoir and involving a nucleation process via the formation of a liquid bridge. The principal difference between the DMFT results and DMC is the replacement of a distribution of nucleation times and location along the pore for the formation of liquid bridges by a single time and location. DMFT is seen to yield an otherwise qualitatively accurate description of the dynamic behavior.

  17. Dynamics of capillary condensation in lattice gas models of confined fluids: A comparison of dynamic mean field theory with dynamic Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Edison, John R.; Monson, Peter A.

    2013-06-01

    This article addresses the accuracy of a dynamic mean field theory (DMFT) for fluids in porous materials [P. A. Monson, J. Chem. Phys. 128, 084701 (2008)], 10.1063/1.2837287. The theory is used to study the relaxation processes of fluids in pores driven by step changes made to a bulk reservoir in contact with the pore. We compare the results of the DMFT to those obtained by averaging over large numbers of dynamic Monte Carlo (DMC) simulation trajectories. The problem chosen for comparison is capillary condensation in slit pores, driven by step changes in the chemical potential in the bulk reservoir and involving a nucleation process via the formation of a liquid bridge. The principal difference between the DMFT results and DMC is the replacement of a distribution of nucleation times and location along the pore for the formation of liquid bridges by a single time and location. DMFT is seen to yield an otherwise qualitatively accurate description of the dynamic behavior.

  18. Dynamic lattice-gas model of underpotential deposition

    NASA Astrophysics Data System (ADS)

    Brown, Gregory; Rikvold, Per Arne; Novotny, M. A.; Wieckowski, Andrzej

    1998-03-01

    Underpotential deposition (UPD) is the process by which a monolayer or less of one metal is adsorbed onto the surface of another at electrode potentials more positive than those at which bulk deposition occurs. For particular combinations of metals, lattice-gas models have been formulated and studied using both analytical and numerical techniques. Dynamic Monte Carlo simulations of a lattice-gas model of UPD of copper onto Au(111) in the presence of sulfuric acid are presented. The simulations include adsorption, desorption, and lateral diffusion and span timescales from 10-9 to 10^1 s. The results reproduce the strong asymmetry seen in experimental current profiles that occur after a sudden potential change.(M. H. Hölzle, et al.), J. Electroanal. Chem. \\underbar371, 101 (1994). The simulation technique can also be used to understand features in cyclic-voltammetry profiles, where the applied potential is changed continuously.

  19. Shock wave structure in a lattice gas

    NASA Astrophysics Data System (ADS)

    Broadwell, James E.; Han, Donghee

    2007-05-01

    The motion and structure of shock and expansion waves in a simple particle system, a lattice gas and cellular automaton, are determined in an exact computation. Shock wave solutions, also exact, of a continuum description, a model Boltzmann equation, are compared with the lattice results. The comparison demonstrates that, as proved by Caprino et al. ["A derivation of the Broadwell equation," Commun. Math. Phys. 135, 443 (1991)] only when the lattice processes are stochastic is the model Boltzmann description accurate. In the strongest shock wave, the velocity distribution function is the bimodal function proposed by Mott-Smith.

  20. Gradient Driven Flow: Lattice Gas, Diffusion Equation and Measurement Scales

    DTIC Science & Technology

    2001-01-01

    03-200 1 Journal Article (refereed) 2001 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Gradient Driven Flow : Lattice Gas, Diffusion Equation and...time regime, the collective motion exhibits an onset of oscillation. 15. SUBJECT TERMS Diffusion; Fick’s Law; Gradient Driven Flow ; Lattice Gas 16...Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 20010907 062 Gradient driven flow : lattice gas, diffusion equation and measurement scales R.B

  1. Lattice gas dynamics under continuous measurement

    NASA Astrophysics Data System (ADS)

    Patil, Yogesh Sharad; Cheung, Hil F. H.; Madjarov, Ivaylo S.; Chen, Huiyao Y.; Vengalattore, Mukund

    2016-05-01

    The act of measurement has a profound consequences quantum systems. While this backaction has so far been discussed as being a limitation on the precision of measurements, it is increasingly being appreciated that measurement backaction is a powerful and versatile means of quantum control. We have previously demonstrated that backaction from position measurement can modify the coherent tunneling rate of a lattice gas through the Quantum Zeno effect. Here, we show how spatially designed measurement landscapes can be used to realize entropy segregation in lattice gases. This presents an alternate path to the longstanding challenge of realizing lattice gases with sufficiently low entropy to access regimes of correlated quantum behavior such as Néel ordered states. This work is supported by the ARO MURI on non-equilibrium dynamics.

  2. Dynamic behavior of multirobot systems using lattice gas automata

    NASA Astrophysics Data System (ADS)

    Stantz, Keith M.; Cameron, Stewart M.; Robinett, Rush D., III; Trahan, Michael W.; Wagner, John S.

    1999-07-01

    Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems (or swarms). Our group has been studying the collective, autonomous behavior of these such systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi- agents architectures. Our goal is to coordinate a constellation of point sensors using unmanned robotic vehicles (e.g., RATLERs, Robotic All-Terrain Lunar Exploration Rover- class vehicles) that optimizes spatial coverage and multivariate signal analysis. An overall design methodology evolves complex collective behaviors realized through local interaction (kinetic) physics and artificial intelligence. Learning objectives incorporate real-time operational responses to environmental changes. This paper focuses on our recent work understanding the dynamics of many-body systems according to the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's rate of deformation, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent nonlinearity of the dynamical equations describing large ensembles, stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots maneuvering past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with

  3. A (reactive) lattice-gas approach to economic cycles

    NASA Astrophysics Data System (ADS)

    Ausloos, Marcel; Clippe, Paulette; Miśkiewicz, Janusz; Peķalski, Andrzej

    2004-12-01

    A microscopic approach to macroeconomic features is intended. A model for macroeconomic behavior under heterogeneous spatial economic conditions is reviewed. A birth-death lattice gas model taking into account the influence of an economic environment on the fitness and concentration evolution of economic entities is numerically and analytically examined. The reaction-diffusion model can also be mapped onto a high-order logistic map. The role of the selection pressure along various dynamics with entity diffusion on a square symmetry lattice has been studied by Monte-Carlo simulation. The model leads to a sort of phase transition for the fitness gap as a function of the selection pressure and to cycles. The control parameter is a (scalar) “business plan”. The business plan(s) allows for spin-offs or merging and enterprise survival evolution law(s), whence bifurcations, cycles and chaotic behavior.

  4. Residual entropy and waterlike anomalies in the repulsive one dimensional lattice gas

    SciTech Connect

    Silva, Fernando Barbosa V. da; Oliveira, Fernando Albuquerque; Barbosa, Marco Aurélio A.

    2015-04-14

    The thermodynamics and kinetics of the one dimensional lattice gas with repulsive interaction are investigated using transfer matrix technique and Monte Carlo simulations. This simple model is shown to exhibit waterlike anomalies in density, thermal expansion coefficient, and self-diffusion. An unified description for the thermodynamic anomalies in this model is achieved based on the ground state residual entropy which appears in the model due to mixing entropy in a ground state phase transition.

  5. Dynamics of a lattice gas system of three species

    NASA Astrophysics Data System (ADS)

    Wang, Yuanshi; Wu, Hong; Liang, Junhao

    2016-10-01

    This paper considers a mutualism system of three species in which each species provides resource for the next one in a one-directional loop, while there exists spatial competition among them. The system is characterized by a lattice gas model and the cases of obligate mutualisms, obligate-facultative mutualisms and facultative mutualisms are considered. Using dynamical systems theory, it is shown that (i) the mutualisms can lead to coexistence of species; (ii) A weak mutualism or an extremely strong mutualism will result in extinction of species, while even the superior facultative species will be driven into extinction by its over-strong mutualism on the next one; (iii) Initial population density plays a role in the coexistence of species. It is also shown that when there exists weak mutualism, an obligate species can survive by providing more benefit to the next one, and the inferior facultative species will not be driven into extinction if it can strengthen its mutualism on the next species. Moreover, Hopf bifurcation, saddle-node bifurcation and bifurcation of heteroclinic cycles are shown in the system. Projection method is extended to exhibit bistability in the three-dimensional model: when saddle-node bifurcation occurs, stable manifold of the saddle-node point divides intR+3 into two basins of attraction of two equilibria. Furthermore, Lyapunov method is applied to exhibit unstability of heteroclinic cycles. Numerical simulations confirm and extend our results.

  6. Robust thermal boundary conditions applicable to a wall along which temperature varies in lattice-gas cellular automata.

    PubMed

    Shim, Jae Wan; Gatignol, Renée

    2010-04-01

    We show that the heat exchange between fluid particles and boundary walls can be achieved by controlling the velocity change rate following the particles' collision with a wall in discrete kinetic theory, such as the lattice-gas cellular automata and the lattice Boltzmann method. We derive a relation between the velocity change rate and temperature so that we can control the velocity change rate according to a given temperature boundary condition. This relation enables us to deal with the thermal boundary whose temperature varies along a wall in contrast to the previous works of the lattice-gas cellular automata. In addition, we present simulation results to compare our method to the existing and give an example in a microchannel with a high temperature gradient boundary condition by the lattice-gas cellular automata.

  7. Transport of a lattice gas under continuous measurement

    NASA Astrophysics Data System (ADS)

    Cheung, Hil F. H.; Patil, Yogesh Sharad; Madjarov, Ivaylo S.; Chen, Huiyao Y.; Vengalattore, Mukund

    2016-05-01

    The act of measurement has a profound consequence on a quantum system. While this backaction has hitherto been discussed as a limitation to the precision of measurements, it is increasingly being appreciated that measurement backaction is a powerful means of quantum control. We have previously demonstrated that backaction from position measurement can modify the coherent tunneling rate of a lattice gas through the Quantum Zeno effect. By suitably designing measurement landscapes we can control the transport properties of the lattice gas. We describe a quantitative study of lattice gas dynamics under continuous quantum measurement in the context of a quantum to classical transition where the atom dynamics goes from a quantum walk at low measurement strengths to classical diffusion at high measurement strengths. We further discuss the prospect of using disorder measurement landscapes to realize a new form of Anderson localization. This work is supported by the ARO MURI on non-equilibrium dynamics.

  8. Theory of multicolor lattice gas - A cellular automaton Poisson solver

    NASA Technical Reports Server (NTRS)

    Chen, H.; Matthaeus, W. H.; Klein, L. W.

    1990-01-01

    The present class of models for cellular automata involving a quiescent hydrodynamic lattice gas with multiple-valued passive labels termed 'colors', the lattice collisions change individual particle colors while preserving net color. The rigorous proofs of the multicolor lattice gases' essential features are rendered more tractable by an equivalent subparticle representation in which the color is represented by underlying two-state 'spins'. Schemes for the introduction of Dirichlet and Neumann boundary conditions are described, and two illustrative numerical test cases are used to verify the theory. The lattice gas model is equivalent to a Poisson equation solution.

  9. The Classical Lattice-Gas Method

    DTIC Science & Technology

    1999-02-01

    also be fixed obstacles with which the particles have perfectly elastic collisions. For example, one can simulate vortex shedding in a fluid flowing ...cause an attractive force between particles giving rise to an athermal liquid-gas phase transition.4 To simulate the correct macroscopic dynamics , the...rheology of mul- tiphase dynamics is driven by low Reynolds number flows . The rheology of droplets (for example 3 The first lattice Boltzmann simulations

  10. High-density equation of state for a lattice gas.

    PubMed

    Ushcats, M V

    2015-05-01

    For the lattice gas models of arbitrary geometry and dimensions with absolute repulsion between particles at zero distance (a hard core identical to a single lattice site) and arbitrary repulsion or attraction at other distances, the "hole-particle" symmetry of the system potential energy has been stated and an equation of state has been derived on the basis of the classical Gibbs statistics. The equation is completely analogous to the well-known virial equation of state, except that it is more accurate at high-density states, while the virial equation has the low-density limitation. Both equations contain the common set of the so-called irreducible integrals, related to the corresponding virial coefficients, and can be used together to describe the behavior of a lattice gas in a wide range of densities.

  11. Spontaneous formation of large clusters in a lattice gas above the critical point.

    PubMed

    Khain, Evgeniy; Khasin, Michael; Sander, Leonard M

    2014-12-01

    We consider clustering of particles in the lattice gas model above the critical point. We find the probability for large density fluctuations over scales much larger than the correlation length. This fundamental problem is of interest in various biological contexts such as quorum sensing and clustering of motile, adhesive, cancer cells. In the latter case, it may give a clue to the problem of growth of recurrent tumors. We develop a formalism for the analysis of this rare event employing a phenomenological master equation and measuring the transition rates in numerical simulations. The spontaneous clustering is treated in the framework of the eikonal approximation to the master equation.

  12. Spontaneous formation of large clusters in a lattice gas above the critical point

    NASA Astrophysics Data System (ADS)

    Khain, Evgeniy; Khasin, Michael; Sander, Leonard M.

    2014-12-01

    We consider clustering of particles in the lattice gas model above the critical point. We find the probability for large density fluctuations over scales much larger than the correlation length. This fundamental problem is of interest in various biological contexts such as quorum sensing and clustering of motile, adhesive, cancer cells. In the latter case, it may give a clue to the problem of growth of recurrent tumors. We develop a formalism for the analysis of this rare event employing a phenomenological master equation and measuring the transition rates in numerical simulations. The spontaneous clustering is treated in the framework of the eikonal approximation to the master equation.

  13. An Efficient and Accurate Quantum Lattice-Gas Model for the Many-Body Schroedinger Wave Equation

    DTIC Science & Technology

    2002-01-01

    CONTRACT NUMBER AN EFFICIENT AND ACCURATE QUANTUM LATTICE-GAS MODEL FOR THE MANY-BODY SCHROEDINGER WAVE EQUATION 5b. GRANT NUMBER SC. PROGRAM ELEMENT...for simulating the time-dependent evolution of a many-body jiiantum mechanical system of particles governed by the non-relativistic Schroedinger " wave...the numerical dispersion of the simulated wave packets is compared with the analytical solutions. 15. SUBJECT TERM: Schroedinger wave equation

  14. Lattice gas automata for flow and transport in geochemical systems

    SciTech Connect

    Janecky, D.R.; Chen, S.; Dawson, S.; Eggert, K.C.; Travis, B.J.

    1992-01-01

    Lattice gas automata models are described, which couple solute transport with chemical reactions at mineral surfaces within pore networks. Diffusion in a box calculations are illustrated, which compare directly with Fickian diffusion. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because hydrodynamic transport, solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible.

  15. Lattice gas automata for flow and transport in geochemical systems

    SciTech Connect

    Janecky, D.R.; Chen, S.; Dawson, S.; Eggert, K.C.; Travis, B.J.

    1992-05-01

    Lattice gas automata models are described, which couple solute transport with chemical reactions at mineral surfaces within pore networks. Diffusion in a box calculations are illustrated, which compare directly with Fickian diffusion. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because hydrodynamic transport, solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible.

  16. Thermodynamics of a lattice gas with linear attractive potential

    SciTech Connect

    Pirjol, Dan; Schat, Carlos

    2015-01-15

    We study the equilibrium thermodynamics of a one-dimensional lattice gas with interaction V(|i−j|)=−1/(μn) (ξ−1/n |i−j|) given by the superposition of a universal attractive interaction with strength −1/(μn) ξ<0, and a linear attractive potential 1/(μn{sup 2}) |i−j|. The interaction is rescaled with the lattice size n, such that the thermodynamical limit n → ∞ is well-behaved. The thermodynamical properties of the system can be found exactly, both for a finite size lattice and in the thermodynamical limit n → ∞. The lattice gas can be mapped to a system of non-interacting bosons which are placed on known energy levels. The exact solution shows that the system has a liquid-gas phase transition for ξ > 0. In the large temperature limit T ≫ T{sub 0}(ρ) = ρ{sup 2}/(4μ) with ρ the density, the system becomes spatially homogeneous, and the equation of state is given to a good approximation by a lattice version of the van der Waals equation, with critical temperature T{sub c}{sup (vdW)}=1/(12μ) (3ξ−1)

  17. Microscopic reversibility and macroscopic irreversibility: A lattice gas model

    NASA Astrophysics Data System (ADS)

    Pérez-Cárdenas, Fernando C.; Resca, Lorenzo; Pegg, Ian L.

    2016-09-01

    We present coarse-grained descriptions and computations of the time evolution of a lattice gas system of indistinguishable particles, whose microscopic laws of motion are exactly reversible, in order to investigate how or what kind of macroscopically irreversible behavior may eventually arise. With increasing coarse-graining and number of particles, relative fluctuations of entropy rapidly decrease and apparently irreversible behavior unfolds. Although that behavior becomes typical in those limits and within a certain range, it is never absolutely irreversible for any individual system with specific initial conditions. Irreversible behavior may arise in various ways. We illustrate one possibility by replacing detailed integer occupation numbers at lattice sites with particle probability densities that evolve diffusively.

  18. Measurement-Induced Localization of an Ultracold Lattice Gas

    NASA Astrophysics Data System (ADS)

    Patil, Y. S.; Chakram, S.; Vengalattore, M.

    2015-10-01

    The process of measurement can modify the state of a quantum system and its subsequent evolution. Here, we demonstrate the control of quantum tunneling in an ultracold lattice gas by the measurement backaction imposed by the act of imaging the atoms, i.e., light scattering. By varying the rate of light scattering from the atomic ensemble, we show the crossover from the weak measurement regime, where position measurements have little influence on tunneling dynamics, to the strong measurement regime, where measurement-induced localization causes a large suppression of tunneling—a manifestation of the quantum Zeno effect. Our study realizes an experimental demonstration of the paradigmatic Heisenberg microscope and sheds light on the implications of measurement on the coherent evolution of a quantum system.

  19. History dependent quantum random walks as quantum lattice gas automata

    SciTech Connect

    Shakeel, Asif E-mail: dmeyer@math.ucsd.edu Love, Peter J. E-mail: dmeyer@math.ucsd.edu; Meyer, David A. E-mail: dmeyer@math.ucsd.edu

    2014-12-15

    Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.

  20. Dynamical Behavior of Multi-Robot Systems Using Lattice Gas Automata

    SciTech Connect

    Cameron, S.M.; Robinett, R.; Stantz, K.M.; Trahan, M.W.; Wagner, J.S.

    1999-03-11

    Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems. Our group has been studying the collective behavior of autonomous, multi-agent systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi-robotic and multi-agents architectures. Our goal is to coordinate a constellation of point sensors that optimizes spatial coverage and multivariate signal analysis using unmanned robotic vehicles (e.g., RATLERs, Robotic All-ten-sin Lunar Exploration Rover-class vehicles). Overall design methodology is to evolve complex collective behaviors realized through simple interaction (kinetic) physics and artificial intelligence to enable real-time operational responses to emerging threats. This paper focuses on our recent work understanding the dynamics of many-body systems using the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's deformation rate, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent non-linearity of the dynamical equations describing large ensembles, development of stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots that maneuvers past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with knowledge, the

  1. Catalytic formation of ammonia: a lattice gas non-thermal Langmuir Hinshelwood mechanism

    NASA Astrophysics Data System (ADS)

    Khan, K. M.; Ahmad, N.; Albano, E. V.

    2001-11-01

    The catalytic formation of ammonia synthesis through dimers N 2 and H 2 has been studied through Monte-Carlo simulation via a model based on lattice gas non-thermal Langmuir-Hinshelwood mechanism, which involves the precursor motion of H 2 molecule. The most interesting feature of this model is it yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The phase diagram is qualitatively similar to well-known ZGB model. The width of the window depends upon the mobility of precursors. The continuous transition disappears when mobility of precursors is extended to third nearest neighbourhood. The dependence of production rate on partial pressure of hydrogen is predicted by simple mathematical equations in our model. Some more interesting results are observed when reaction between precursors and chemisorbed hydrogen atoms is considered.

  2. Crackling sound generation during the formation of liquid bridges: A lattice gas model

    NASA Astrophysics Data System (ADS)

    Almeida, Alexandre B.; Buldyrev, Sergey V.; Alencar, Adriano M.

    2013-08-01

    Due to abnormal mechanical instabilities, liquid bridges may form in the small airways blocking airflow. Liquid bridge ruptures during inhalation are the major cause of the crackling adventitious lung sound, which can be heard using a simple stethoscope. Recently, Vyshedskiy and colleagues (2009) [1] described and characterized a crackle sound originated during expiration. However, the mechanism and origin of the expiratory crackle are still controversial. Thus, in this paper, we propose a mechanism for expiratory crackles. We hypothesize that the expiratory crackle sound is a result of the energy released in the form of acoustic waves during the formation of the liquid bridge. The magnitude of the energy released is proportional to the difference in free energy prior and after the bridge formation. We use a lattice gas model to describe the liquid bridge formation between two parallel planes. Specifically, we determine the surface free energy and the conditions of the liquid bridge formation between two parallel planes separated by a distance 2h by a liquid droplet of volume Ω and contact angle Θ, using both Monte Carlo simulation of a lattice gas model and variational calculus based on minimization of the surface area with the volume and the contact angle constrained. We numerically and analytically determine the phase diagram of the system as a function of the dimensionless parameter hΩ and Θ. We can distinguish two different phases: one droplet and one liquid bridge. We observe a hysteresis curve for the energy changes between these two states, and a finite size effect in the bridge formation. We compute the release of free energy during the formation of the liquid bridge and discuss the results in terms of system size. We also calculate the force exerted from liquid bridge on the planes by studying the dependence of the free energy on the separation between the planes 2h. The simulation results are in agreement with the analytical solution.

  3. Nucleation in a Potts lattice gas model of crystallization from solution

    NASA Astrophysics Data System (ADS)

    Duff, Nathan; Peters, Baron

    2009-11-01

    Nucleation from solution is important in many pharmaceutical crystallization, biomineralization, material synthesis, and self-assembly processes. Simulation methodology has progressed rapidly for studies of nucleation in pure component and implicit solvent systems; however little progress has been made in the simulation of explicit solvent systems. The impasse stems from the inability of rare events simulation methodology to be combined with simulation techniques which maintain a constant chemical potential driving force (supersaturation) for nucleation. We present a Potts lattice gas (PLG) to aid in the development of new simulation strategies for nucleation from solution. The PLG captures common crystallization phase diagram features such as a eutectic point and solute/solvent melting points. Simulations of the PLG below the bulk solute melting temperature reveal a competition between amorphous and crystalline nuclei. As the temperature is increased toward the bulk melting temperature, the nucleation pathway changes from a one step crystalline nucleation pathway to a two step pathway, where an amorphous nucleus forms and then crystallizes. We explain these results in terms of classical nucleation theory with different size-dependant chemical potentials for the amorphous and crystalline nucleation pathways. The two step pathway may be particularly important when crystallization is favored only at postcritical sizes.

  4. Enantiomeric phase separation in a lattice gas model: Guggenheim approximation

    NASA Astrophysics Data System (ADS)

    Huckaby, Dale A.; Shinmi, Masato; Ausloos, Marcel; Clippe, Paulette

    1986-05-01

    We consider a lattice gas in which the two enantiomeric forms of a tetrahedral molecule, consisting of a central carbon atom bonded to four different groups A, B, G, and H, are adsorbed onto a triangular lattice, such that the carbon atom is above a lattice site, the three bonds to A, B, and G point toward neighboring lattice sites, and the bond to H points perpendicular to and away from the plane of the lattice. For a certain choice of intermolecular interactions, such as may exist between the zwitterion forms of an amino acid, the phase diagram was investigated using a Guggenheim approximation with two order parameters. Enantiomeric phase separation into two symmetric condensed phases occurs at low temperatures. These condensed phases become a single racemic condensed phase at a critical line, and they are in equilibrium with a racemic gas phase along a line of triple points. These two lines coincide at a critical endpoint. The racemic condensed and gas phases are in equilibrium along a two phase coexistence line which begins at the critical endpoint and ends at a critical point. No tricritical point was found in the model for the special choice of interactions studied.

  5. Solution of an associating lattice-gas model with density anomaly on a Husimi lattice

    NASA Astrophysics Data System (ADS)

    Oliveira, Tiago J.; Stilck, Jürgen F.; Barbosa, Marco Aurélio A.

    2010-11-01

    We study a model of a lattice gas with orientational degrees of freedom which resemble the formation of hydrogen bonds between the molecules. In this model, which is the simplified version of the Henriques-Barbosa model, no distinction is made between donors and acceptors in the bonding arms. We solve the model in the grand-canonical ensemble on a Husimi lattice built with hexagonal plaquettes with a central site. The ground state of the model, which was originally defined on the triangular lattice, is exactly reproduced by the solution on this Husimi lattice. In the phase diagram, one gas and two liquid [high density liquid (HDL) and low density liquid (LDL)] phases are present. All phase transitions (GAS-LDL, GAS-HDL, and LDL-HDL) are discontinuous, and the three phases coexist at a triple point. A line of temperatures of maximum density in the isobars is found in the metastable GAS phase, as well as another line of temperatures of minimum density appears in the LDL phase, part of it in the stable region and another in the metastable region of this phase. These findings are at variance with simulational results for the same model on the triangular lattice, which suggested a phase diagram with two critical points. However, our results show very good quantitative agreement with the simulations, both for the coexistence loci and the densities of particles and of hydrogen bonds. We discuss the comparison of the simulations with our results.

  6. Solution of an associating lattice-gas model with density anomaly on a Husimi lattice.

    PubMed

    Oliveira, Tiago J; Stilck, Jürgen F; Barbosa, Marco Aurélio A

    2010-11-01

    We study a model of a lattice gas with orientational degrees of freedom which resemble the formation of hydrogen bonds between the molecules. In this model, which is the simplified version of the Henriques-Barbosa model, no distinction is made between donors and acceptors in the bonding arms. We solve the model in the grand-canonical ensemble on a Husimi lattice built with hexagonal plaquettes with a central site. The ground state of the model, which was originally defined on the triangular lattice, is exactly reproduced by the solution on this Husimi lattice. In the phase diagram, one gas and two liquid [high density liquid (HDL) and low density liquid (LDL)] phases are present. All phase transitions (GAS-LDL, GAS-HDL, and LDL-HDL) are discontinuous, and the three phases coexist at a triple point. A line of temperatures of maximum density in the isobars is found in the metastable GAS phase, as well as another line of temperatures of minimum density appears in the LDL phase, part of it in the stable region and another in the metastable region of this phase. These findings are at variance with simulational results for the same model on the triangular lattice, which suggested a phase diagram with two critical points. However, our results show very good quantitative agreement with the simulations, both for the coexistence loci and the densities of particles and of hydrogen bonds. We discuss the comparison of the simulations with our results.

  7. Multiple phase transitions in extended hard-core lattice gas models in two dimensions.

    PubMed

    Nath, Trisha; Rajesh, R

    2014-07-01

    We study the k-NN hard-core lattice gas model in which the first k next-nearest-neighbor sites of a particle are excluded from occupation by other particles on a two-dimensional square lattice. This model is the lattice version of the hard-disk system with increasing k corresponding to decreasing lattice spacing. While the hard-disk system is known to undergo a two-step freezing process with increasing density, the lattice model has been known to show only one transition. Here, based on Monte Carlo simulations and high-density expansions of the free energy and density, we argue that for k = 4,10,11,14,⋯, the lattice model undergoes multiple transitions with increasing density. Using Monte Carlo simulations, we confirm the same for k = 4,...,11. This, in turn, resolves an existing puzzle as to why the 4-NN model has a continuous transition against the expectation of a first-order transition.

  8. When is a quantum cellular automaton (QCA) a quantum lattice gas automaton (QLGA)?

    NASA Astrophysics Data System (ADS)

    Shakeel, Asif; Love, Peter J.

    2013-09-01

    Quantum cellular automata (QCA) are models of quantum computation of particular interest from the point of view of quantum simulation. Quantum lattice gas automata (QLGA - equivalently partitioned quantum cellular automata) represent an interesting subclass of QCA. QLGA have been more deeply analyzed than QCA, whereas general QCA are likely to capture a wider range of quantum behavior. Discriminating between QLGA and QCA is therefore an important question. In spite of much prior work, classifying which QCA are QLGA has remained an open problem. In the present paper we establish necessary and sufficient conditions for unbounded, finite QCA (finitely many active cells in a quiescent background) to be QLGA. We define a local condition that classifies those QCA that are QLGA, and we show that there are QCA that are not QLGA. We use a number of tools from functional analysis of separable Hilbert spaces and representation theory of associative algebras that enable us to treat QCA on finite but unbounded configurations in full detail.

  9. Thermal phase transitions in a honeycomb lattice gas with three-body interactions.

    PubMed

    Lohöfer, Maximilian; Bonnes, Lars; Wessel, Stefan

    2013-11-01

    We study the thermal phase transitions in a classical (hard-core) lattice gas model with nearest-neighbor three-body interactions on the honeycomb lattice, based on parallel tempering Monte Carlo simulations. This system realizes incompressible low-temperature phases at fractional fillings of 9/16, 5/8, and 3/4 that were identified in a previous study of a related quantum model. In particular, both the 9/16 and the 5/8 phase exhibit an extensive ground-state degeneracy reflecting the frustrated nature of the three-body interactions on the honeycomb lattice. The thermal melting of the 9/16 phase is found to be a first-order, discontinuous phase transition. On the other hand, from the thermodynamic behavior we obtain indications for a four-states Potts-model thermal transition out of the 5/8 phase. We find that this thermal Potts-model transition relates to the selection of one out of four extensive sectors within the low-energy manifold of the 5/8 phase, which we obtain via an exact mapping of the ground-state manifold to a hard-core dimer model on an embedded honeycomb superlattice.

  10. Monte Carlo tests of nucleation concepts in the lattice gas model

    NASA Astrophysics Data System (ADS)

    Schmitz, Fabian; Virnau, Peter; Binder, Kurt

    2013-05-01

    The conventional theory of homogeneous and heterogeneous nucleation in a supersaturated vapor is tested by Monte Carlo simulations of the lattice gas (Ising) model with nearest-neighbor attractive interactions on the simple cubic lattice. The theory considers the nucleation process as a slow (quasistatic) cluster (droplet) growth over a free energy barrier ΔF*, constructed in terms of a balance of surface and bulk term of a critical droplet of radius R*, implying that the rates of droplet growth and shrinking essentially balance each other for droplet radius R=R*. For heterogeneous nucleation at surfaces, the barrier is reduced by a factor depending on the contact angle. Using the definition of physical clusters based on the Fortuin-Kasteleyn mapping, the time dependence of the cluster size distribution is studied for quenching experiments in the kinetic Ising model and the cluster size ℓ* where the cluster growth rate changes sign is estimated. These studies of nucleation kinetics are compared to studies where the relation between cluster size and supersaturation is estimated from equilibrium simulations of phase coexistence between droplet and vapor in the canonical ensemble. The chemical potential is estimated from a lattice version of the Widom particle insertion method. For large droplets it is shown that the physical clusters have a volume consistent with the estimates from the lever rule. Geometrical clusters (defined such that each site belonging to the cluster is occupied and has at least one occupied neighbor site) yield valid results only for temperatures less than 60% of the critical temperature, where the cluster shape is nonspherical. We show how the chemical potential can be used to numerically estimate ΔF* also for nonspherical cluster shapes.

  11. Lattice gas dynamics: application to driven vortices in two dimensional superconductors.

    PubMed

    Gotcheva, Violeta; Wang, Albert T J; Teitel, S

    2004-06-18

    A continuous time Monte Carlo lattice gas dynamics is developed to model driven steady states of vortices in two dimensional superconducting networks. Dramatic differences are found when compared to a simpler Metropolis dynamics. Subtle finite size effects are found at low temperature, with a moving smectic that becomes unstable to an anisotropic liquid on sufficiently large length scales.

  12. Slow relaxation and aging kinetics for the driven lattice gas.

    PubMed

    Daquila, George L; Täuber, Uwe C

    2011-05-01

    We numerically investigate the long-time behavior of the density-density autocorrelation function in driven lattice gases with particle exclusion and periodic boundary conditions in one, two, and three dimensions using precise Monte Carlo simulations. In the one-dimensional asymmetric exclusion process on a ring with half the lattice sites occupied, we find that correlations induce extremely slow relaxation to the asymptotic power law decay. We compare the crossover functions obtained from our simulations with various analytic results in the literature and analyze the characteristic oscillations that occur in finite systems away from half-filling. As expected, in three dimensions correlations are weak and consequently the mean-field description is adequate. We also investigate the relaxation toward the nonequilibrium steady state in the two-time density-density autocorrelations, starting from strongly correlated initial conditions. We obtain simple aging scaling behavior in one, two, and three dimensions, with the expected power laws.

  13. COMMENT: Comment on 'Transverse fluctuations in the driven lattice gas'

    NASA Astrophysics Data System (ADS)

    Albano, Ezequiel V.

    2004-08-01

    Extensive simulation results of the transverse fluctuations in two driven lattice gases, the classical one with current and a modified version without current, are in agreement with the field theory proposed by Garrido et al (GSM). Based on the facts that results from both models are indistinguishable and they obey excellent scaling only by using GSM exponents, I concluded that the conclusions of the recent letter by Caracciolo et al are flawed.

  14. Fluctuations in an ordered c (2×2) two-dimensional lattice-gas system with repulsive interactions

    NASA Astrophysics Data System (ADS)

    Argyrakis, P.; Chumak, A. A.; Maragakis, M.

    2005-06-01

    Fluctuations of the particle density in an ordered c(2×2) two-dimensional lattice-gas system are studied both analytically and by means of Monte Carlo simulations. The ordering is caused by a strong interparticle repulsive interaction resulting in the second order phase transition. The lattice of adsorption sites is divided into two sublattices (almost filled and almost empty sublattices) each of which contains a small number of structural “defects,” i.e., vacancies and excess particles. The relaxation of the correlation function of fluctuations turns out to be governed by two different functions. This peculiarity is to be contrasted with the traditional fluctuation theory which predicts the existence of a single damping constant, determined by the collective diffusion coefficient. A specific thesis of the proposed approach is that transport phenomena in ordered systems may be described in terms of both displacements and generation-recombination of structural defects. Accordingly, the correlation function of fluctuations depends on diffusion coefficients of two defect species as well as on the generation-recombination frequency. Our theory reduces to the usual one when fluctuations occur under local equilibrium conditions, i.e., for a sufficiently large size of probe areas and not too great values of interaction parameter. The analytical results agree well with those obtained in the Monte Carlo framework.

  15. Effect of disorder on condensation in the lattice gas model on a random graph

    NASA Astrophysics Data System (ADS)

    Handford, Thomas P.; Dear, Alexander; Pérez-Reche, Francisco J.; Taraskin, Sergei N.

    2014-07-01

    The lattice gas model of condensation in a heterogeneous pore system, represented by a random graph of cells, is studied using an exact analytical solution. A binary mixture of pore cells with different coordination numbers is shown to exhibit two phase transitions as a function of chemical potential in a certain temperature range. Heterogeneity in interaction strengths is demonstrated to reduce the critical temperature and, for large-enough degreeS of disorder, divides the cells into ones which are either on average occupied or unoccupied. Despite treating the pore space loops in a simplified manner, the random-graph model provides a good description of condensation in porous structures containing loops. This is illustrated by considering capillary condensation in a structural model of mesoporous silica SBA-15.

  16. Study of the critical behavior of the driven lattice gas model with limited nonequilibrium dynamics

    NASA Astrophysics Data System (ADS)

    Saracco, Gustavo P.; Rubio Puzzo, M. Leticia; Bab, Marisa A.

    2017-02-01

    In this paper the nonequilibrium critical behavior is investigated using a variant of the well-known two-dimensional driven lattice gas (DLG) model, called modified driven lattice gas (MDLG). In this model, the application of the external field is regulated by a parameter p ɛ [ 0 , 1 ] in such a way that if p = 0, the field is not applied, and it becomes the Ising model, while if p = 1, the DLG model is recovered. The behavior of the model is investigated for several values of p by studying the dynamic evolution of the system within the short-time regime in the neighborhood of a phase transition. It is found that the system experiences second-order phase transitions in all the interval of p for the density of particles ρ = 0.5. The determined critical temperatures Tc(p) are greater than the critical temperature of the Ising model TcI, and increase with p up to the critical temperature of the DLG model in the limit of infinite driving fields. The dependence of Tc(p) on p is compatible with a power-law behavior whose exponent is ψ = 0.27(3) . Furthermore, the complete set of the critical and the anisotropic exponents is estimated. For the smallest value of p, the ​dynamics and β exponents are close to that calculated for the Ising model, and the anisotropic exponent Δ is near zero. As p is increased, the exponents and Δ change, meaning that the anisotropy effects increase. For the largest value investigated, the set of exponents approaches to that reported by the most recent theoretical framework developed for the DLG model.

  17. Knot invariants and the thermodynamics of lattice gas automata. Final technical report, April 15, 1991--July 14, 1995

    SciTech Connect

    Meyer, D.A.

    1995-12-01

    The goal of this project has been to build on the understanding of the connections between knot invariants, exactly solvable statistical mechanics models and discrete dynamical systems gained in earlier work, toward an answer to the question of how early and robust thermodynamic behavior appears in lattice gas automata. These investigations have recently become relevant, unanticipatedly, to crucial issues in quantum computation.

  18. Microcanonical Monte Carlo study of one dimensional self-gravitating lattice gas models

    NASA Astrophysics Data System (ADS)

    Maciel, Joao Marcos; Amato, Marco Antônio; da Rocha Filho, Tarcisio Marciano; Figueiredo, Annibal D.

    2017-03-01

    In this study we present a microcanonical Monte Carlo investigation of one dimensional (1 - d) self-gravitating toy models. We study the effect of hard-core potentials and compare to the results obtained with softening parameters and also the effect of the topology on these systems. In order to study the effect of the topology in the system we introduce a model with the symmetry of motion in a line instead of a circle, which we denominate as 1 /r model. The hard-core particle potential introduces the effect of the size of particles and, consequently, the effect of the density of the system that is redefined in terms of the packing fraction of the system. The latter plays a role similar to the softening parameter ɛ in the softened particles' case. In the case of low packing fractions both models with hard-core particles show a behavior that keeps the intrinsic properties of the three dimensional gravitational systems such as negative heat capacity. For higher values of the packing fraction the ring model behaves as the potential for the standard cosine Hamiltonian Mean Field model while for the 1 /r model it is similar to the one-dimensional systems. In the present paper we intend to show that a further simplification level is possible by introducing the lattice-gas counterpart of such models, where a drastic simplification of the microscopic state is obtained by considering a local average of the exact N-body dynamics.

  19. Analysis of individual cell trajectories in lattice-gas cellular automaton models for migrating cell populations.

    PubMed

    Mente, Carsten; Voss-Böhme, Anja; Deutsch, Andreas

    2015-04-01

    Collective dynamics of migrating cell populations drive key processes in tissue formation and maintenance under normal and diseased conditions. Collective cell behavior at the tissue level is typically characterized by considering cell density patterns such as clusters and moving cell fronts. However, there are also important observables of collective dynamics related to individual cell behavior. In particular, individual cell trajectories are footprints of emergent behavior in populations of migrating cells. Lattice-gas cellular automata (LGCA) have proven successful to model and analyze collective behavior arising from interactions of migrating cells. There are well-established methods to analyze cell density patterns in LGCA models. Although LGCA dynamics are defined by cell-based rules, individual cells are not distinguished. Therefore, individual cell trajectories cannot be analyzed in LGCA so far. Here, we extend the classical LGCA framework to allow labeling and tracking of individual cells. We consider cell number conserving LGCA models of migrating cell populations where cell interactions are regulated by local cell density and derive stochastic differential equations approximating individual cell trajectories in LGCA. This result allows the prediction of complex individual cell trajectories emerging in LGCA models and is a basis for model-experiment comparisons at the individual cell level.

  20. Lattice-Gas Automata for the Problem Of Kinetic Theory of Gas During Free Expansion

    NASA Astrophysics Data System (ADS)

    Khotimah, Siti Nurul; Arif, Idam; Liong, The Houw

    The lattice-gas method has been applied to solve the problem of kinetic theory of gas in the Gay-Lussac-Joule experiment. Numerical experiments for a two-dimensional gas were carried out to determine the number of molecules in one vessel (Nr), the ratio between the mean square values of the components of molecule velocity (/line{vx2}//line{v_y^2}), and the change in internal energy (ΔU) as a function of time during free expansion. These experiments were repeated for different sizes of an aperture in the partition between the two vessels. After puncturing the partition, the curve for the particle number in one vessel shows a damped oscillation for about half of the total number. The oscillations do not vanish after a sampling over different initial configurations. The system is in nonequilibrium due to the pressure equilibration, and here the flow is actually compressible. The equilibration time (in time steps) decreases with decreased size of aperture in the partition. For very small apertures (equal or less than 9{√{3}}/{2} lattice units), the number of molecules in one vessel changes with time in a smooth way until it reaches half of the total number; their curves obey the analytical solution for quasi-static processes. The calculations on /line{vx2}//line{v_y^2} and ΔU also support the results that the equilibration time decreases with decreased size of aperture in the partition.

  1. Thermodynamic properties of water in the lattice gas model with consideration of the vibrational motions of molecules

    NASA Astrophysics Data System (ADS)

    Titov, S. V.; Tovbin, Yu. K.

    2016-11-01

    A molecular model developed earlier for a polar fluid within the lattice gas model is supplemented by considering the vibrational motions of molecules using water as an example. A combination of point dipole and Lennard-Jones potentials from SPC parametrization is chosen as the force field model for the molecule. The main thermodynamic properties of liquid water (density, internal energy, and entropy) are studied as functions of temperature. There is qualitative agreement between the calculation results and the experimental data. Ways of refining the molecular theory are discussed.

  2. Parameter estimation with a novel gradient-based optimization method for biological lattice-gas cellular automaton models.

    PubMed

    Mente, Carsten; Prade, Ina; Brusch, Lutz; Breier, Georg; Deutsch, Andreas

    2011-07-01

    Lattice-gas cellular automata (LGCAs) can serve as stochastic mathematical models for collective behavior (e.g. pattern formation) emerging in populations of interacting cells. In this paper, a two-phase optimization algorithm for global parameter estimation in LGCA models is presented. In the first phase, local minima are identified through gradient-based optimization. Algorithmic differentiation is adopted to calculate the necessary gradient information. In the second phase, for global optimization of the parameter set, a multi-level single-linkage method is used. As an example, the parameter estimation algorithm is applied to a LGCA model for early in vitro angiogenic pattern formation.

  3. Dynamic mean field theory for lattice gas models of fluids confined in porous materials: higher order theory based on the Bethe-Peierls and path probability method approximations.

    PubMed

    Edison, John R; Monson, Peter A

    2014-07-14

    Recently we have developed a dynamic mean field theory (DMFT) for lattice gas models of fluids in porous materials [P. A. Monson, J. Chem. Phys. 128(8), 084701 (2008)]. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable states for fluids in pores and is especially useful for studying system exhibiting adsorption/desorption hysteresis. In this paper we discuss the extension of the theory to higher order by means of the path probability method (PPM) of Kikuchi and co-workers. We show that this leads to a treatment of the dynamics that is consistent with thermodynamics coming from the Bethe-Peierls or Quasi-Chemical approximation for the equilibrium or metastable equilibrium states of the lattice model. We compare the results from the PPM with those from DMFT and from dynamic Monte Carlo simulations. We find that the predictions from PPM are qualitatively similar to those from DMFT but give somewhat improved quantitative accuracy, in part due to the superior treatment of the underlying thermodynamics. This comes at the cost of greater computational expense associated with the larger number of equations that must be solved.

  4. Dynamic mean field theory for lattice gas models of fluids confined in porous materials: Higher order theory based on the Bethe-Peierls and path probability method approximations

    SciTech Connect

    Edison, John R.; Monson, Peter A.

    2014-07-14

    Recently we have developed a dynamic mean field theory (DMFT) for lattice gas models of fluids in porous materials [P. A. Monson, J. Chem. Phys. 128(8), 084701 (2008)]. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable states for fluids in pores and is especially useful for studying system exhibiting adsorption/desorption hysteresis. In this paper we discuss the extension of the theory to higher order by means of the path probability method (PPM) of Kikuchi and co-workers. We show that this leads to a treatment of the dynamics that is consistent with thermodynamics coming from the Bethe-Peierls or Quasi-Chemical approximation for the equilibrium or metastable equilibrium states of the lattice model. We compare the results from the PPM with those from DMFT and from dynamic Monte Carlo simulations. We find that the predictions from PPM are qualitatively similar to those from DMFT but give somewhat improved quantitative accuracy, in part due to the superior treatment of the underlying thermodynamics. This comes at the cost of greater computational expense associated with the larger number of equations that must be solved.

  5. Transfer-matrix study of a hard-square lattice gas with two kinds of particles and density anomaly

    NASA Astrophysics Data System (ADS)

    Oliveira, Tiago J.; Stilck, Jürgen F.

    2015-09-01

    Using transfer matrix and finite-size scaling methods, we study the thermodynamic behavior of a lattice gas with two kinds of particles on the square lattice. Only excluded volume interactions are considered, so that the model is athermal. Large particles exclude the site they occupy and its four first neighbors, while small particles exclude only their site. Two thermodynamic phases are found: a disordered phase where large particles occupy both sublattices with the same probability and an ordered phase where one of the two sublattices is preferentially occupied by them. The transition between these phases is continuous at small concentrations of the small particles and discontinuous at larger concentrations, both transitions are separated by a tricritical point. Estimates of the central charge suggest that the critical line is in the Ising universality class, while the tricritical point has tricritical Ising (Blume-Emery-Griffiths) exponents. The isobaric curves of the total density as functions of the fugacity of small or large particles display a minimum in the disordered phase.

  6. Phase diagram of a bidispersed hard-rod lattice gas in two dimensions

    NASA Astrophysics Data System (ADS)

    Kundu, Joyjit; Stilck, Jürgen F.; Rajesh, R.

    2015-12-01

    We obtain, using extensive Monte Carlo simulations, virial expansion and a high-density perturbation expansion about the fully packed monodispersed phase, the phase diagram of a system of bidispersed hard rods on a square lattice. We show numerically that when the length of the longer rods is 7, two continuous transitions may exist as the density of the longer rods is increased, keeping the density of shorter rods fixed: first from a low-density isotropic phase to a nematic phase, and second from the nematic to a high-density isotropic phase. The difference between the critical densities of the two transitions decreases to zero at a critical density of the shorter rods so that the fully packed phase is disordered for any composition. When both the rod lengths are larger than 6, we observe the existence of two transitions along the fully packed line as the composition is varied. Low-density virial expansion, truncated at the second virial coefficient, reproduces features of the first transition. By developing a high-density perturbation expansion, we show that when one of the rods is long enough, there will be at least two isotropic-nematic transitions along the fully packed line as the composition is varied.

  7. (QC Themes) Type-Two Quantum Computing in PBG-Based Cavities for Efficient Simulation of Lattice Gas Dynamics

    DTIC Science & Technology

    2008-04-26

    intensity of one of the mixed beams at a substrate will be proportional to 1+cos f, much as in the Mach -Zehnder interferometer f23g from classical...Dürr, G. Rempe, E. G. M. van Kempen, and B. J. Verhaa, Phys. Rev. Lett. 89, 283202 s2002d. f44g T. Volz, S. Dürr, S. Ernst , A. Marte, and G. Rempe

  8. One-dimensional lattices topologically equivalent to two-dimensional lattices within the context of the lattice gas model, III. The hexagonal lattice

    NASA Astrophysics Data System (ADS)

    Costanza, E. F.; Costanza, G.

    2017-02-01

    Continuum partial differential equations are obtained from a set of discrete stochastic evolution equations of both non-Markovian and Markovian processes and applied to the diffusion within the context of the lattice gas model. A procedure allowing to construct one-dimensional lattices that are topologically equivalent to two-dimensional lattices is described in detail in the case of a hexagonal lattice which has the particular feature that need four types of dynamical variables. This example shows additional features to the general procedure and some extensions are also suggested in order to provide a wider insight in the present approach.

  9. One-dimensional lattices topologically equivalent to two-dimensional lattices within the context of the lattice gas model. II The triangular lattice

    NASA Astrophysics Data System (ADS)

    Costanza, E. F.; Costanza, G.

    2016-12-01

    Continuum partial differential equations are obtained from a set of discrete stochastic evolution equations of both non-Markovian and Markovian processes and applied to the diffusion within the context of the lattice gas model. A procedure allowing to construct one-dimensional lattices that are topologically equivalent to two-dimensional lattices is described in detail in the case of a triangular lattice. This example shows the general features that possess the procedure and extensions are also suggested in order to provide a wider insight in the present approach.

  10. Solutions for correlations along the coexistence curve and at the critical point of a kagomé lattice gas with three-particle interactions

    NASA Astrophysics Data System (ADS)

    Barry, J. H.; Muttalib, K. A.; Tanaka, T.

    2008-01-01

    We consider a two-dimensional (d=2) kagomé lattice gas model with attractive three-particle interactions around each triangular face of the kagomé lattice. Exact solutions are obtained for multiparticle correlations along the liquid and vapor branches of the coexistence curve and at criticality. The correlation solutions are also determined along the continuation of the curvilinear diameter of the coexistence region into the disordered fluid region. The method generates a linear algebraic system of correlation identities with coefficients dependent only upon the interaction parameter. Using a priori knowledge of pertinent solutions for the density and elementary triplet correlation, one finds a closed and linearly independent set of correlation identities defined upon a spatially compact nine-site cluster of the kagomé lattice. Resulting exact solution curves of the correlations are plotted and discussed as functions of the temperature and are compared with corresponding results in a traditional kagomé lattice gas having nearest-neighbor pair interactions. An example of application for the multiparticle correlations is demonstrated in cavitation theory.

  11. AFOSR Initiative Element: Lattice-Gas Automata and Lattice Boltzmann Methods as a Novel Parallel Computing Strategy

    DTIC Science & Technology

    2006-05-31

    methods. LBE is a generalization of LGA, where single- particle distributions are encoded directly using real numbers. The simulation dynamics is driven...local cellular automaton rule (A.14) does not explicitly show any mixing of particle flow directions. That fact that (A.14) does represent collisional ... dynamics simulation , provides the researcher with complete system de- tails not obtainable by either empirical or analytical treatments. LGA as a

  12. Interface dynamics of immiscible two-phase lattice-gas cellular automata: A model with random dynamic scatterers and quenched disorder in two dimensions

    NASA Astrophysics Data System (ADS)

    Azevedo, R. M.; Montenegro-Filho, R. R.; Coutinho-Filho, M. D.

    2013-09-01

    We use a lattice gas cellular automata model in the presence of random dynamic scattering sites and quenched disorder in the two-phase immiscible model with the aim of producing an interface dynamics similar to that observed in Hele-Shaw cells. The dynamics of the interface is studied as one fluid displaces the other in a clean lattice and in a lattice with quenched disorder. For the clean system, if the fluid with a lower viscosity displaces the other, we show that the model exhibits the Saffman-Taylor instability phenomenon, whose features are in very good agreement with those observed in real (viscous) fluids. In the system with quenched disorder, we obtain estimates for the growth and roughening exponents of the interface width in two cases: viscosity-matched fluids and the case of unstable interface. The first case is shown to be in the same universality class of the random deposition model with surface relaxation. Moreover, while the early-time dynamics of the interface behaves similarly, viscous fingers develop in the second case with the subsequent production of bubbles in the context of a complex dynamics. We also identify the Hurst exponent of the subdiffusive fractional Brownian motion associated with the interface, from which we derive its fractal dimension and the universality classes related to a percolation process.

  13. Interface dynamics of immiscible two-phase lattice-gas cellular automata: a model with random dynamic scatterers and quenched disorder in two dimensions.

    PubMed

    Azevedo, R M; Montenegro-Filho, R R; Coutinho-Filho, M D

    2013-09-01

    We use a lattice gas cellular automata model in the presence of random dynamic scattering sites and quenched disorder in the two-phase immiscible model with the aim of producing an interface dynamics similar to that observed in Hele-Shaw cells. The dynamics of the interface is studied as one fluid displaces the other in a clean lattice and in a lattice with quenched disorder. For the clean system, if the fluid with a lower viscosity displaces the other, we show that the model exhibits the Saffman-Taylor instability phenomenon, whose features are in very good agreement with those observed in real (viscous) fluids. In the system with quenched disorder, we obtain estimates for the growth and roughening exponents of the interface width in two cases: viscosity-matched fluids and the case of unstable interface. The first case is shown to be in the same universality class of the random deposition model with surface relaxation. Moreover, while the early-time dynamics of the interface behaves similarly, viscous fingers develop in the second case with the subsequent production of bubbles in the context of a complex dynamics. We also identify the Hurst exponent of the subdiffusive fractional Brownian motion associated with the interface, from which we derive its fractal dimension and the universality classes related to a percolation process.

  14. Parallel Markov chain Monte Carlo simulations.

    PubMed

    Ren, Ruichao; Orkoulas, G

    2007-06-07

    With strict detailed balance, parallel Monte Carlo simulation through domain decomposition cannot be validated with conventional Markov chain theory, which describes an intrinsically serial stochastic process. In this work, the parallel version of Markov chain theory and its role in accelerating Monte Carlo simulations via cluster computing is explored. It is shown that sequential updating is the key to improving efficiency in parallel simulations through domain decomposition. A parallel scheme is proposed to reduce interprocessor communication or synchronization, which slows down parallel simulation with increasing number of processors. Parallel simulation results for the two-dimensional lattice gas model show substantial reduction of simulation time for systems of moderate and large size.

  15. Parallel Markov chain Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Ren, Ruichao; Orkoulas, G.

    2007-06-01

    With strict detailed balance, parallel Monte Carlo simulation through domain decomposition cannot be validated with conventional Markov chain theory, which describes an intrinsically serial stochastic process. In this work, the parallel version of Markov chain theory and its role in accelerating Monte Carlo simulations via cluster computing is explored. It is shown that sequential updating is the key to improving efficiency in parallel simulations through domain decomposition. A parallel scheme is proposed to reduce interprocessor communication or synchronization, which slows down parallel simulation with increasing number of processors. Parallel simulation results for the two-dimensional lattice gas model show substantial reduction of simulation time for systems of moderate and large size.

  16. Monte Carlo simulation of liquid bridge rupture: Application to lung physiology

    NASA Astrophysics Data System (ADS)

    Alencar, Adriano M.; Wolfe, Elie; Buldyrev, Sergey V.

    2006-08-01

    In the course of certain lung diseases, the surface properties and the amount of fluids coating the airways changes and liquid bridges may form in the small airways blocking the flow of air, impairing gas exchange. During inhalation, these liquid bridges may rupture due to mechanical instability and emit a discrete sound event called pulmonary crackle, which can be heard using a simple stethoscope. We hypothesize that this sound is a result of the acoustical release of energy that had been stored in the surface of liquid bridges prior to its rupture. We develop a lattice gas model capable of describing these phenomena. As a step toward modeling this process, we address a simpler but related problem, that of a liquid bridge between two planar surfaces. This problem has been analytically solved and we use this solution as a validation of the lattice gas model of the liquid bridge rupture. Specifically, we determine the surface free energy and critical stability conditions in a system containing a liquid bridge of volume Ω formed between two parallel planes, separated by a distance 2h , with a contact angle Θ using both Monte Carlo simulation of a lattice gas model and variational calculus based on minimization of the surface area with the volume and the contact angle constraints. In order to simulate systems with different contact angles, we vary the parameters between the constitutive elements of the lattice gas. We numerically and analytically determine the phase diagram of the system as a function of the dimensionless parameters hΩ-1/3 and Θ . The regions of this phase diagram correspond to the mechanical stability and thermodynamical stability of the liquid bridge. We also determine the conditions for the symmetrical versus asymmetrical rupture of the bridge. We numerically and analytically compute the release of free energy during rupture. The simulation results are in agreement with the analytical solution. Furthermore, we discuss the results in connection

  17. Monte Carlo simulation of liquid bridge rupture: application to lung physiology.

    PubMed

    Alencar, Adriano M; Wolfe, Elie; Buldyrev, Sergey V

    2006-08-01

    In the course of certain lung diseases, the surface properties and the amount of fluids coating the airways changes and liquid bridges may form in the small airways blocking the flow of air, impairing gas exchange. During inhalation, these liquid bridges may rupture due to mechanical instability and emit a discrete sound event called pulmonary crackle, which can be heard using a simple stethoscope. We hypothesize that this sound is a result of the acoustical release of energy that had been stored in the surface of liquid bridges prior to its rupture. We develop a lattice gas model capable of describing these phenomena. As a step toward modeling this process, we address a simpler but related problem, that of a liquid bridge between two planar surfaces. This problem has been analytically solved and we use this solution as a validation of the lattice gas model of the liquid bridge rupture. Specifically, we determine the surface free energy and critical stability conditions in a system containing a liquid bridge of volume Omega formed between two parallel planes, separated by a distance 2h, with a contact angle Theta using both Monte Carlo simulation of a lattice gas model and variational calculus based on minimization of the surface area with the volume and the contact angle constraints. In order to simulate systems with different contact angles, we vary the parameters between the constitutive elements of the lattice gas. We numerically and analytically determine the phase diagram of the system as a function of the dimensionless parameters hOmega(-1/3) and Theta. The regions of this phase diagram correspond to the mechanical stability and thermodynamical stability of the liquid bridge. We also determine the conditions for the symmetrical versus asymmetrical rupture of the bridge. We numerically and analytically compute the release of free energy during rupture. The simulation results are in agreement with the analytical solution. Furthermore, we discuss the results in

  18. Long-Range Lattice-Gas Algorithm

    DTIC Science & Technology

    2007-11-02

    lattice-gases, and therefore inherits exact computabil- ity on a discrete spacetime lattice. Our contribution is the use of nonlocal interactions that...gases, and therefore inherits exact computability on a discrete spacetime lattice. Our contribution is the use of nonlocal interactions that allow us to

  19. Coarse-graining the computations of surface reactions: Nonlinear dynamics from atomistic simulators

    NASA Astrophysics Data System (ADS)

    Makeev, Alexei G.; Kevrekidis, Ioannis G.

    2009-06-01

    We review and discuss the use of equation-free computation in extracting coarse-grained, nonlinear dynamics information from atomistic (lattice-gas) models of surface reactions. The approach is based on circumventing the explicit derivation of macroscopic equations for the system statistics (e.g., average coverage). Short bursts of appropriately initialized computational experimentation with the lattice-gas simulator are designed "on demand" and processed in the spirit of the coarse timestepper introduced in Theodoropoulos et al. (2000) (K. Theodoropoulos, Y.-H. Qian, I.G. Kevrekidis, Proc. Natl. Acad. Sci. USA 97 (2000) 9840). The information derived from these computational experiments, processed through traditional, continuum numerical methods is used to solve the macroscopic equations without ever deriving them in closed form. The approach is illustrated through two computational examples: the CO oxidation reaction, and the NO + CO/Pt(1 0 0) reaction.

  20. Simulation research on pedestrian counter flow subconscious behavior

    NASA Astrophysics Data System (ADS)

    Li, Yongxing; Jia, Hongfei; Zhou, Ya-Nan; Yang, Lili

    Analyzing the pedestrian subconscious behavior and walking environment in the passage, right-moving preference subconscious strength and overtaking subconscious strength are introduced into the pedestrian simulation model which is based on lattice gas model. Two pedestrian subconscious behavior simulation models, which are distinguished by whether considering pedestrian flow ratio of two directions or not, are established respectively. With the platform of MATLAB software, the simulations of pedestrian counter flow subconscious behavior are realized. The simulations indicate that compared with the pedestrian subconscious behavior simulation model without considering the pedestrian flow ratio of two directions, the model that considers the pedestrian flow ratio of two directions is better in simulating the pedestrian subconscious behavior.

  1. Surface-subsurface model for a dimer-dimer catalytic reaction: a Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Khan, K. M.; Albano, E. V.

    2002-02-01

    The surface-subsurface model for a dimer-dimer reaction of the type A2 + 2B2→2AB2 has been studied through Monte Carlo simulation via a model based on the lattice gas non-thermal Langmuir-Hinshelwood mechanism, which involves the precursor motion of the B2 molecule. The motion of precursors is considered on the surface as well as in the subsurface. The most interesting feature of this model is that it yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The phase diagram is qualitatively similar to the well known Ziff, Gulari and Barshad (ZGB) model. The width of the window depends upon the mobility of precursors. The continuous transition disappears when the mobility of the surface precursors is extended to the third-nearest neighbourhood. The dependence of production rate on partial pressure of B2 dimer is predicted by simple mathematical equations in our model.

  2. Kinetic Monte Carlo Simulation of Epitaxial Thin Film Growth: Formation of Submonolayer Islands and Multilayer Mounds

    SciTech Connect

    Evans, J. W.; Thiel, P. A.; Li, Maozhi

    2007-06-14

    We consider homoepitaxy (or low-misfit heteroepitaxy) via vapor deposition or MBE under UHV conditions. Thin film growth is initiated by nucleation and growth of 2D islands in the submonolayer regime. For atoms subsequently deposited on top of islands, a step edge barrier often inhibits downward transport and produces kinetic roughening during multilayer growth. Such unstable growth is characterized by the formation of 3D mounds (multilayer stacks of 2D islands). Kinetic Monte Carlo (KMC) simulation of suitable atomistic lattice-gas models can address fundamental or general issues related to both submonolayer and multilayer film evolution, and can also provide a predictive tool for morphological evolution in specific systems. Examples of the successes of KMC modeling are provided for metal homoepitaxial film growth, specifically for contrasting behavior in the classic Ag/Ag(100) and Ag/Ag(111) systems.

  3. Simulation estimates of cloud points of polydisperse fluids.

    PubMed

    Buzzacchi, Matteo; Sollich, Peter; Wilding, Nigel B; Müller, Marcus

    2006-04-01

    We describe two distinct approaches to obtaining the cloud-point densities and coexistence properties of polydisperse fluid mixtures by Monte Carlo simulation within the grand-canonical ensemble. The first method determines the chemical potential distribution mu(sigma) (with the polydisperse attribute) under the constraint that the ensemble average of the particle density distribution rho(sigma) match a prescribed parent form. Within the region of phase coexistence (delineated by the cloud curve) this leads to a distribution of the fluctuating overall particle density n, p(n), that necessarily has unequal peak weights in order to satisfy a generalized lever rule. A theoretical analysis shows that as a consequence, finite-size corrections to estimates of coexistence properties are power laws in the system size. The second method assigns mu(sigma) such that an equal-peak-weight criterion is satisfied for p(n) for all points within the coexistence region. However, since equal volumes of the coexisting phases cannot satisfy the lever rule for the prescribed parent, their relative contributions must be weighted appropriately when determining mu(sigma). We show how to ascertain the requisite weight factor operationally. A theoretical analysis of the second method suggests that it leads to finite-size corrections to estimates of coexistence properties which are exponentially small in the system size. The scaling predictions for both methods are tested via Monte Carlo simulations of a polydisperse lattice-gas model near its cloud curve, the results showing excellent quantitative agreement with the theory.

  4. Monte Carlo simulation studies of diffusion in crowded environments

    NASA Astrophysics Data System (ADS)

    Nandigrami, Prithviraj; Grove, Brandy; Konya, Andrew; Selinger, Robin

    Anomalous diffusion has been observed in protein solutions and other multi-component systems due to macromolecular crowding. Using Monte Carlo simulations, we investigate mechanisms that govern anomalous diffusive transport and pattern formation in a crowded mixture. We consider a multi-component lattice gas model with ``tracer'' molecules diffusing across a density gradient in a solution containing sticky ``crowder'' molecules that cluster to form dynamically evolving obstacles. The dependence of tracer flux on crowder density shows an intriguing re-entrant behavior as a function of temperature with three distinct temperature regimes. At high temperature, crowders segregate near the tracer sink but, for low enough overall crowder density, remain sufficiently disordered to allow continuous tracer flux. At intermediate temperature, crowders segregate and block tracer flux entirely, giving rise to complex pattern formation. At low temperature, crowders aggregate to form small, slowly diffusing obstacles. The resulting tracer flux shows scaling behavior near the percolation threshold, analogous to the scenario when the obstacles are fixed and randomly distributed. Our simulations predict distinct quantitative dependence of tracer flux on crowder density in these temperature limits.

  5. Simulating granular media on the computer

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.

    Granular materials, like sand or powder, can present very intriguing effects. When shaken, sheared or poured they show segregation, convection and spontaneous fluctuations in densities and stresses. I will discuss the modeling of a granular medium on a computer by simulating a packing of elastic spheres via Molecular Dynamics. Dissipation of energy and shear friction at collisions are included. In the physical range the friction coefficient is found to be a linear function of the angle of repose. On a vibrating plate the formation of convection cells due to walls or amplitude modulations can be observed. The onset of fluidization can be determined and is in good agreement with experiments. Segregation of larger particles is found to be always accompanied by convection cells. There is also ample experimental evidence showing the existence of spontaneous density patterns in granular material flowing through pipes or hoppers. The Molecular Dynamics simulations show that these density fluctuations follow a 1/f α spectrum. I compare this behavior to deterministic one-dimensional traffic models. A model with continuous positions and velocities shows self-organized critical jamming behind a slower car. The experimentally observed effects are also reproduced by Lattice Gas and Boltzmann Lattice Models. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow. We also briefly sketch a thermodynamic formalism for loose granular material. In a dense packing non-linear acoustic phenomena, like the pressure dependence of the sound velocity are studied. Finally the plastic shear bands occurring in large scale deformations of compactified granular media are investigated using an explicit Lagrangian technique.

  6. Kinetic Monte Carlo simulations of electrodeposition: Crossover from continuous to instantaneous homogeneous nucleation within Avrami’s law

    NASA Astrophysics Data System (ADS)

    Frank, Stefan; Rikvold, Per Arne

    2006-06-01

    The influence of lateral adsorbate diffusion on the dynamics of the first-order phase transition in a two-dimensional Ising lattice gas with attractive nearest-neighbor interactions is investigated by means of kinetic Monte Carlo simulations. For example, electrochemical underpotential deposition proceeds by this mechanism. One major difference from adsorption in vacuum surface science is that under control of the electrode potential and in the absence of mass-transport limitations, local adsorption equilibrium is approximately established. We analyze our results using the theory of Kolmogorov, Johnson and Mehl, and Avrami (KJMA), which we extend to an exponentially decaying nucleation rate. Such a decay may occur due to a suppression of nucleation around existing clusters in the presence of lateral adsorbate diffusion. Correlation functions prove the existence of such exclusion zones. By comparison with microscopic results for the nucleation rate I and the interface velocity of the growing clusters v, we can show that the KJMA theory yields the correct order of magnitude for Iv2. This is true even though the spatial correlations mediated by diffusion are neglected. The decaying nucleation rate causes a gradual crossover from continuous to instantaneous nucleation, which is complete when the decay of the nucleation rate is very fast on the time scale of the phase transformation. Hence, instantaneous nucleation can be homogeneous, producing negative minima in the two-point correlation functions. We also present in this paper an n-fold way Monte Carlo algorithm for a square lattice gas with adsorption/desorption and lateral diffusion.

  7. A simulation test of the optical Kerr mechanism for laser-induced nucleation

    NASA Astrophysics Data System (ADS)

    Knott, Brandon C.; Doherty, Michael F.; Peters, Baron

    2011-04-01

    Recent experiments have demonstrated that intense, nanosecond laser pulses can induce crystal nucleation from supersaturated solutions that are transparent at the incident wavelengths, a phenomenon termed nonphotochemical laser-induced nucleation (NPLIN). Previous work has proposed that this effect is due to the alignment of solute molecules in solution due to the electric field of the applied laser light, promoting crystalline order. We have used simulations of NPLIN to examine how an orientational bias in solution affects nucleation with Monte Carlo simulations of a Potts lattice gas model. We examine this effect within both a classical, one-step nucleation framework as well as in the context of two-step nucleation. Our results indicate that an orientational bias can reduce the free energy barrier to nucleation within the one-step picture as well as promote the crystallization of amorphous precritical nuclei (the rate-determining step in the two-step picture). However, these effects are only present with field strengths that are much greater than those used in experiments.

  8. Computer simulations studies of the catalytic oxidation of carbon monoxide on platinum metals

    NASA Astrophysics Data System (ADS)

    Kaukonen, H.-P.; Nieminen, R. M.

    1989-10-01

    The steady-state catalytic oxidation process of carbon monoxide on platinum metal surfaces is studied using two irreversible kinetic computer simulation models: (a) An extended version of the model introduced by Ziff, Gulari, and Barshad (ZGB) with the effects of CO desorption and diffusion as well as finite reaction probability taken into account. The different physical processes, diffusion and desorption are studied independently and their effect on the equilibrium window, i.e., the regime where steady CO2 formation occurs is determined. (b) An interaction model where adatom-adatom nearest-neighbor (nn) interactions are taken explicitly into account through Boltzmann terms J1, J2, and J3 which are the energies of the CO-CO, O-O, and CO-O interactions, respectively. The phase diagrams in the temperature-CO-partial pressure (T,pCO-) plane are determined for different values of the nn interactions. The behavior of the system is dependent on the sign of J1(=J2 in the simulations) as well as the sign of the difference J1-J3. There is thus a clear analogy with a two-component equilibrium lattice gas with nn interactions.

  9. Electrochemical behavior of a typical redox mediator on a modified electrode surface: Experiment and computer simulations

    NASA Astrophysics Data System (ADS)

    Gavilán Arriazu, E. M.; Paz Zanini, Verónica I.; Gulotta, Florencia A.; Araujo, Virginia M.; Pinto, O. A.

    2017-04-01

    This paper describes the study of a redox species electrosorption on a modified electrode by experimental measurements and computer simulation. The propose model is based on the fact that charges are transferred to the electrode when an electroactive species is adsorbed on its surface. The electrode surface is modified by the irreversible adsorption of a non-electroactive species, which blocks a percentage of the adsorption sites. Hence, the electroactive species can only be adsorbed on the surface vacancies, and, when this phenomenon occurs, interact laterally with the non-electroactive one. Lattice-gas models and Monte Carlo simulations in the Gran Canonical Ensemble are used. The analysis conducted is based on the study of adsorption isotherms and voltammograms, for several values of energies and adsorption degrees of the non-electroactive species. In the case of experimental measurements, an artificial clay (Laponite®) represents the non-electroactive species while the redox probe Fe(CN)64- is the electroactive one. The results obtained by the proposed model are compared with experimental voltammograms.

  10. Coherent Rayleigh-Brillouin Scattering in High Intensity Laser Fields: Optical Lattice gas Heating (Briefing Charts)

    DTIC Science & Technology

    2012-07-01

    ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NO. Air Force Research Laboratory (AFMC) AFRL/RQRC 10 E. Saturn Blvd. Edwards AFB CA 93524-7680...unlimited CRBS Results Low Intensity • Experiment and DSMC show good agreement with six-moment model (s6) for low intensity (X. Pan , “Coherent

  11. Quantum Algorithms for Computational Physics: Volume 3 of Lattice Gas Dynamics

    DTIC Science & Technology

    2007-01-03

    spacetime -dependent quantity, proportional to the probability of particle occupation, the modulus squared of the wave function. The numerical solution...Chapter 4 The Dirac equation 4.1 Introduction Finding a simple rule to represent the spacetime quantum mechanical dynamics of a system of Dirac particles...Ising spin system with nearest-neighbor spin-spin interaction [Jacobson and Schulman, 1984]. The 1+1 dimensional chessboard is a square spacetime lat

  12. Spin-Based Lattice-Gas Quantum Computers in Solids Using Optical Addressing

    DTIC Science & Technology

    2007-04-30

    As the length of the first pulse is increased the Rabi nutation in the echo amplitude is clearly visible. Here, only the in-phase part of the echo...4 6 10 12 14 4 1 i 20 Length of first pulse (microsec) Figure 2. Observation of Rabi nutation (single qubit rotations) using photon echo readout. (a...field is applied, the Kramer’s degenerate spin sublevels split due to the Zeeman effect. Here, the effect of an axial magnetic field (along the ion

  13. Recovery of the Navier-Stokes equations using a lattice-gas Boltzmann method

    NASA Technical Reports Server (NTRS)

    Chen, Hudong; Chen, Shiyi; Matthaeus, William H.

    1992-01-01

    A lattice Boltzmann model is presented which gives the complete Navier-Stokes equation and may provide an efficient parallel numerical method for solving various fluid problems. The model uses the single-time relaxation approximation and a particular Maxwell-type distribution. The model eliminates exactly (1) the non-Galilean invariance caused by a density-dependent coefficient in the convection term and (2) a velocity-dependent equation of state.

  14. Lattice-Gas Model Description of Kinetic Roughening and Fluctuations in Chemical Wave Propagation

    NASA Astrophysics Data System (ADS)

    Tammaro, Michael; Evans, Jim

    1996-03-01

    The ZGB model [1] for CO-oxidation on surfaces displays a discontinuous transition from a reactive to a CO-poisoned state, with increasing CO partial pressure. We consider the evolution of the interface between these two states in the vicinity of the poisoning transition [2]. We observe large ``intrinsic fluctuations" at the interface of the order of 10-20 lattice spacings, together with the gradual development of long-wavelength fluctuations. The latter are described by the KPZ-theory for noise-induced kinetic roughening of driven interfaces, for CO partial pressures strictly below the poisoning transition. Distinct behavior is observed and characterized right at the transition. We also show that the influence of introducing surface diffusion of adsorbed reactants into the model is to dramatically quench the intrinsic fluctuations. [1] R.M. Ziff, E. Gulari, and Y. Barshad, Phys. Rev. Lett. 56, p.2553 (1986). [2] J.W. Evans and T.R. Ray, Phys. Rev. E 50, p.4302 (1994).

  15. Dynamic mean field theory for lattice gas models of fluid mixtures confined in mesoporous materials.

    PubMed

    Edison, J R; Monson, P A

    2013-11-12

    We present the extension of dynamic mean field theory (DMFT) for fluids in porous materials (Monson, P. A. J. Chem. Phys. 2008, 128, 084701) to the case of mixtures. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable equilibrium states for fluids in pores after a change in the bulk pressure or composition. It is especially useful for studying systems where there are capillary condensation or evaporation transitions. Nucleation processes associated with these transitions are emergent features of the theory and can be visualized via the time dependence of the density distribution and composition distribution in the system. For mixtures an important component of the dynamics is relaxation of the composition distribution in the system, especially in the neighborhood of vapor-liquid interfaces. We consider two different types of mixtures, modeling hydrocarbon adsorption in carbon-like slit pores. We first present results on bulk phase equilibria of the mixtures and then the equilibrium (stable/metastable) behavior of these mixtures in a finite slit pore and an inkbottle pore. We then use DMFT to describe the evolution of the density and composition in the pore in the approach to equilibrium after changing the state of the bulk fluid via composition or pressure changes.

  16. JASMINE simulator

    NASA Astrophysics Data System (ADS)

    Ueda, Seiji; Yamada, Yoshiyuki; Kuwabara, Takashi; Gouda, Naoteru; Tsujimoto, Takuji; Kobayashi, Yukiyasu; Nakajima, Tadashi; Matsuhara, Hideo; Yano, Taihei; Suganuma, Masahiro; Jasmine Working Group

    2005-04-01

    We explain simulation tools in the JASMINE project (JASMINE simulator). The JASMINE project stands at the stage where its basic design will be determined in a few years. Therefore it is very important to simulate the data stream generated by astrometric fields at JASMINE in order to support investigations of error budgets, sampling strategy, data compression, data analysis, scientific performances, etc. We find that new software technologies, such as Object Oriented (OO) methodologies, are ideal tools for the simulation system of JASMINE (the JASMINE simulator). In this article, we explain the framework of the JASMINE simulator.

  17. JASMINE simulator

    NASA Astrophysics Data System (ADS)

    Yamada, Yoshiyuki; Gouda, Naoteru; Yano, Taihei; Kobayashi, Yukiyasu; Tsujimoto, Takuji; Suganuma, Masahiro; Niwa, Yoshito; Sako, Nobutada; Hatsutori, Yoichi; Tanaka, Takashi

    2006-06-01

    We explain simulation tools in JASMINE project (JASMINE simulator). The JASMINE project stands at the stage where its basic design will be determined in a few years. Then it is very important to simulate the data stream generated by astrometric fields at JASMINE in order to support investigations into error budgets, sampling strategy, data compression, data analysis, scientific performances, etc. Of course, component simulations are needed, but total simulations which include all components from observation target to satellite system are also very important. We find that new software technologies, such as Object Oriented(OO) methodologies are ideal tools for the simulation system of JASMINE(the JASMINE simulator). In this article, we explain the framework of the JASMINE simulator.

  18. Simulation of selective thermodynamic deposition in nanoholes.

    PubMed

    Pinto, O A; López de Mishima, B A; Leiva, E P M; Oviedo, O A

    2017-01-04

    The deposition of particles in nanoholes is analyzed, taking into account the curvature of their inner walls. Different lattice-gas models of the nanoholes are considered. The heterogeneous surface are shaped from a (100)-surface where a nanohollow are incorporated with parallelepiped or polyhedral geometry. Several deposition stages are identified as a function of the degree of curvature of the inner walls of the nanoholes. The Monte Carlo technique in the grand canonical ensemble is used to calculate isotherms, isosteric heats, energies per site and other thermodynamic properties. This study is based on different magnitudes of the interaction energies between the particles being deposited and those surrounding the nanohole.

  19. JASMINE Simulator

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Gouda, N.; Yano, T.; Kobayashi, Y.; Suganuma, M.; Tsujimoto, T.; Sako, N.; Hatsutori, Y.; Tanaka, T.

    2006-08-01

    We explain simulation tools in JASMINE project (JASMINE simulator). The JASMINE project stands at the stage where its basic design will be determined in a few years. Then it is very important to simulate the data stream generated by astrometric fields at JASMINE in order to support investigations of error budgets, sampling strategy, data compression, data analysis, scientific performances, etc. Of course, component simulations are needed, but total simulations which include all components from observation target to satellite system are also very important. We find that new software technologies, such as Object Oriented (OO) methodologies are ideal tools for the simulation system of JASMINE (the JASMINE simulator). The simulation system should include all objects in JASMINE such as observation techniques, models of instruments and bus design, orbit, data transfer, data analysis etc. in order to resolve all issues which can be expected beforehand and make it easy to cope with some unexpected problems which might occur during the mission of JASMINE. So, the JASMINE Simulator is designed as handling events such as photons from astronomical objects, control signals for devices, disturbances for satellite attitude, by instruments such as mirrors and detectors, successively. The simulator is also applied to the technical demonstration "Nano-JASMINE". The accuracy of ordinary sensor is not enough for initial phase attitude control. Mission instruments may be a good sensor for this purpose. The problem of attitude control in initial phase is a good example of this software because the problem is closely related to both mission instruments and satellite bus systems.

  20. Simulation Accelerator

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Under a NASA SBIR (Small Business Innovative Research) contract, (NAS5-30905), EAI Simulation Associates, Inc., developed a new digital simulation computer, Starlight(tm). With an architecture based on the analog model of computation, Starlight(tm) outperforms all other computers on a wide range of continuous system simulation. This system is used in a variety of applications, including aerospace, automotive, electric power and chemical reactors.

  1. Simulating Science

    ERIC Educational Resources Information Center

    Markowitz, Dina; Holt, Susan

    2011-01-01

    Students use manipulative models and small-scale simulations that promote learning of complex biological concepts. The authors have developed inexpensive wet-lab simulations and manipulative models for "Diagnosing Diabetes," "A Kidney Problem?" and "A Medical Mystery." (Contains 5 figures and 3 online resources.)

  2. Simulated Experiments

    ERIC Educational Resources Information Center

    Snadden, R. B.; Runquist, O.

    1975-01-01

    Presents an experiment in which a programmable calculator is employed as a data generating system for simulated laboratory experiments. The example used as an illustration is a simulated conductimetric titration of an aqueous solution of HC1 with an aqueous solution of NaOH. (Author/EB)

  3. Motion Simulator

    NASA Technical Reports Server (NTRS)

    1993-01-01

    MOOG, Inc. supplies hydraulic actuators for the Space Shuttle. When MOOG learned NASA was interested in electric actuators for possible future use, the company designed them with assistance from Marshall Space Flight Center. They also decided to pursue the system's commercial potential. This led to partnership with InterActive Simulation, Inc. for production of cabin flight simulators for museums, expositions, etc. The resulting products, the Magic Motion Simulator 30 Series, are the first electric powered simulators. Movements are computer-guided, including free fall to heighten the sense of moving through space. A projection system provides visual effects, and the 11 speakers of a digital laser based sound system add to the realism. The electric actuators are easier to install, have lower operating costs, noise, heat and staff requirements. The U.S. Space & Rocket Center and several other organizations have purchased the simulators.

  4. JASMINE simulator

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Gouda, N.; Yano, T.; Sako, N.; Hatsutori, Y.; Tanaka, T.; Yamauchi, M.

    We explain simulation tools in JASMINE project(JASMINE simulator). The JASMINE project stands at the stage where its basic design will be determined in a few years. Then it is very important to simulate the data stream generated by astrometric fields at JASMINE in order to support investigations of error budgets, sampling strategy, data compression, data analysis, scientific performances, etc. Of course, component simulations are needed, but total simulations which include all components from observation target to satellite system are also very important. We find that new software technologies, such as Object Oriented(OO) methodologies are ideal tools for the simulation system of JASMINE(the JASMINE simulator). The simulation system should include all objects in JASMINE such as observation techniques, models of instruments and bus design, orbit, data transfer, data analysis etc. in order to resolve all issues which can be expected beforehand and make it easy to cope with some unexpected problems which might occur during the mission of JASMINE. So, the JASMINE Simulator is designed as handling events such as photons from astronomical objects, control signals for devices, disturbances for satellite attitude, by instruments such as mirrors and detectors, successively. The simulator is also applied to the technical demonstration "Nano-JASMINE". The accuracy of ordinary sensor is not enough for initial phase attitude control. Mission instruments may be a good sensor for this purpose. The problem of attitude control in initial phase is a good example of this software because the problem is closely related to both mission instruments and satellite bus systems.

  5. Kinetic Monte Carlo Simulation of the oscillatory catalytic CO oxidation using a modified Ziff-Gulari-Barshad model

    NASA Astrophysics Data System (ADS)

    Sinha, Indrajit; Mukherjee, Ashim K.

    2014-03-01

    The oxidation of CO on Pt-group metal surfaces has attracted widespread attention since a long time due to its interesting oscillatory kinetics and spatiotemporal behavior. The use of STM in conjunction with other experimental data has confirmed the validity of the surface reconstruction (SR) model under low pressure and the more recent surface oxide (SO) model which is possible under sub-atmospheric pressure conditions [1]. In the SR model the surface is periodically reconstructed below a certain low critical CO-coverage and this reconstruction is lifted above a second, higher critical CO-coverage. Alternatively the SO model proposes periodic switching between a low-reactivity metallic surface and a high-reactivity oxide surface. Here we present an overview of our recent kinetic Monte Carlo (KMC) simulation studies on the oscillatory kinetics of surface catalyzed CO oxidation. Different modifications of the lattice gas Ziff-Gulari-Barshad (ZGB) model have been utilized or proposed for this purpose. First we present the effect of desorption on the ZGB reactive to poisoned irreversible phase transition in the SR model. Next we discuss our recent research on KMC simulation of the SO model. The ZGB framework is utilized to propose a new model incorporating not only the standard Langmuir-Hinshelwood (LH) mechanism, but also introducing the Mars-van Krevelen (MvK) mechanism for the surface oxide phase [5]. Phase diagrams, which are plots between long time averages of various oscillating quantities against the normalized CO pressure, show two or three transitions depending on the CO coverage critical threshold (CT) value beyond which all adsorbed oxygen atoms are converted to surface oxide.

  6. Solar Simulator

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Oriel Corporation's simulators have a high pressure xenon lamp whose reflected light is processed by an optical system to produce a uniform solar beam. Because of many different types of applications, the simulators must be adjustable to replicate many different areas of the solar radiation spectrum. Simulators are laboratory tools for such purposes as testing and calibrating solar cells, or other solar energy systems, testing dyes, paints and pigments, pharmaceuticals and cosmetic preparations, plant and animal studies, food and agriculture studies and oceanographic research.

  7. Mission Simulators

    NASA Video Gallery

    Students will use NASA Web-based simulators to follow sequenced directions and complete ordered tasks while learning how the shuttle is made ready for flight, how the shuttle docks with the Interna...

  8. Wind Simulation

    SciTech Connect

    Walker, Howard Andrew

    2008-12-31

    The Software consists of a spreadsheet written in Microsoft Excel that provides an hourly simulation of a wind energy system, which includes a calculation of wind turbine output as a power-curve fit of wind speed.

  9. Simulation Methodology

    DTIC Science & Technology

    1991-05-01

    to estimate the original probability of the rare event one needs to compensate for the change of measure and this involves using likelihood rations...Glynn Ward Whitt 48 12/89 A New View of the Heavy-Traffic Limit Theorem Peter W. Glynn for Many-Server Queues Ward Whitt 49 12/89 The Covariance...Validity of Sequential Stopping Rules Peter W. Glynn for Stochastic Simulations Ward Whitt 56 02/90 Analysis of Parallel, Replicated Simulations

  10. What can we hope for from cellular automata?

    NASA Astrophysics Data System (ADS)

    Doolen, Gary

    Although the idea of using discrete methods for modeling partial differential equations occured very early, the actual statement that cellular automata techniques can approximate the solutions of hydrodynamic partial differential equations was first discovered by Frisch, Hasslacher, and Pomeau. Their description of the derivation, which assumes the validity of the Boltzmann equation, appeared in the Physical Review Letters in April 1986. It is the intent of this article to provide a description of the simplest lattice gas model and to examine the successes and inadequacies of a lattice gas calculation of flow in a two-dimensional channel. Some comments will summarize a recent result of a lattice gas simulation of flow through porous media, a problem which is ideal for the lattice gas method. Finally, some remarks will be focused on the impressive speeds which could be obtained from a dedicated lattice gas computer.

  11. Simulating Voids

    NASA Astrophysics Data System (ADS)

    Goldberg, David M.; Vogeley, Michael S.

    2004-04-01

    We present a novel method for the simulation of the interior of large cosmic voids, suitable for the study of the formation and evolution of objects lying within such regions. Following Birkhoff's theorem, void regions dynamically evolve as universes with cosmological parameters that depend on the underdensity of the void. We derive the values of ΩM, ΩΛ, and H0 that describe this evolution. We examine how the growth rate of structure and scale factor in a void differ from the background universe. Together with a prescription for the power spectrum of fluctuations, these equations provide the initial conditions for running specialized void simulations. The increased efficiency of such simulations, in comparison to general-purpose simulations, allows an improvement of upward of 20 in the mass resolution. As a sanity check, we run a moderate-resolution simulation (N=1283 particles) and confirm that the resulting mass function of void halos is consistent with other theoretical and numerical models.

  12. Simulation Software

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Various NASA Small Business Innovation Research grants from Marshall Space Flight Center, Langley Research Center and Ames Research Center were used to develop the 'kernel' of COMCO's modeling and simulation software, the PHLEX finite element code. NASA needed it to model designs of flight vehicles; one of many customized commercial applications is UNISIM, a PHLEX-based code for analyzing underground flows in oil reservoirs for Texaco, Inc. COMCO's products simulate a computational mechanics problem, estimate the solution's error and produce the optimal hp-adapted mesh for the accuracy the user chooses. The system is also used as a research or training tool in universities and in mechanical design in industrial corporations.

  13. Simulated Agribusiness.

    ERIC Educational Resources Information Center

    Salisbury, Howard G., III

    "Simulated Agribusiness" is designed to provide the student with a role playing situation dealing with the complexities and problems of modern agriculture. It is a competitive game played on a hypothetical mid-latitude diversified farm in a capitalistic system. The player is faced with a series of decisions which will determine his success or…

  14. Simulating Gravity

    ERIC Educational Resources Information Center

    Pipinos, Savas

    2010-01-01

    This article describes one classroom activity in which the author simulates the Newtonian gravity, and employs the Euclidean Geometry with the use of new technologies (NT). The prerequisites for this activity were some knowledge of the formulae for a particle free fall in Physics and most certainly, a good understanding of the notion of similarity…

  15. Simulating Electrophoresis.

    ERIC Educational Resources Information Center

    Moertel, Cheryl; Frutiger, Bruce

    1996-01-01

    Describes a DNA fingerprinting simulation that uses vegetable food coloring and plastic food containers instead of DNA and expensive gel electrophoresis chambers. Allows students to decipher unknown combinations of dyes in a method similar to that used to decipher samples of DNA in DNA fingerprint techniques. (JRH)

  16. ERA Simulation.

    ERIC Educational Resources Information Center

    Shelly, Ann C.; Wilen, William W.

    1982-01-01

    Presents a simulation which can be used in any secondary social studies course to teach about the Equal Rights Amendment. It can be played with as few as ten and as many as 40 students. Playing time varies from three to seven class periods. (RM)

  17. Simulating Combustion

    NASA Astrophysics Data System (ADS)

    Merker, G.; Schwarz, C.; Stiesch, G.; Otto, F.

    The content spans from simple thermodynamics of the combustion engine to complex models for the description of the air/fuel mixture, ignition, combustion and pollutant formation considering the engine periphery of petrol and diesel engines. Thus the emphasis of the book is on the simulation models and how they are applicable for the development of modern combustion engines. Computers can be used as the engineers testbench following the rules and recommendations described here.

  18. RCS Simulation

    DTIC Science & Technology

    2005-05-01

    store config.) to be considered, Moving parts to be considered · Hybridisation of methods · Fast algorithms, new Aproaches · Geometry representations...Page 2 Military Aircraft Overview • Introduction • Methods ,Tools for mm-wave applications • Examples • Further requirements / developments Page 3...Flexible handling of Geometry · Parametrisation of Geometry Page 4 Military Aircraft Methods for RCS simulations •Fundamental subdivision between full

  19. Spatial signal amplification in cell biology: A lattice-gas model for self-tuned phase ordering

    NASA Astrophysics Data System (ADS)

    Ferraro, T.; de Candia, A.; Gamba, A.; Coniglio, A.

    2008-09-01

    Experiments show that the movement of eukaryotic cells is regulated by a process of phase separation of two competing enzymes on the cell membrane, that effectively amplifies shallow external gradients of chemical attractant. Notably, the cell is able to self-tune the final enzyme concentrations to an equilibrium state of phase coexistence, for a wide range of the average attractant concentration. We propose a simple lattice model in which, together with a short-range attraction between enzymes, a long-range repulsion naturally arises from physical considerations, that easily explains such observed behavior.

  20. Diffusion of small clusters on metal (100) surfaces: Exact master-equation analysis for lattice-gas models

    SciTech Connect

    Sanchez, J.R.; Evans, J.W.

    1999-01-01

    Exact results are presented for the surface diffusion of small two-dimensional clusters, the constituent atoms of which are commensurate with a square lattice of adsorption sites. Cluster motion is due to the hopping of atoms along the cluster perimeter with various rates. We apply the formalism of Titulaer and Deutch [J. Chem. Phys. {bold 77}, 472 (1982)], which describes evolution in reciprocal space via a linear master equation with dimension equal to the number of cluster configurations. We focus on the regime of rapid hopping of atoms along straight close-packed edges, where certain subsets of configurations cycle rapidly between each other. Each such subset is treated as a single quasiconfiguration, thereby reducing the dimension of the evolution equation, simplifying the analysis, and elucidating limiting behavior. We also discuss the influence of concerted atom motions on the diffusion of tetramers and larger clusters. {copyright} {ital 1999} {ital The American Physical Society}

  1. Terrain Simulation

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A highlight of the IMAX film, Blue Planet, is a 100-second computer- generated animation of a flight and earthquake simulation along California's San Andreas Fault. Created by the VESA group at the Jet Propulsion Laboratory, the sequence required the development of a technique to make possible terrain rendering of very large digital images. An image mosaic of California constructed from Landsat data made this possible. An advanced pyramidal terrain rendering technique was developed, significantly reducing the necessary time involved in transferring the Landsat data to film. The new technique has also enabled NASA to develop new perspective rendering technologies in order to cope with anticipated increased remote sensor data.

  2. Flight Simulation.

    DTIC Science & Technology

    1986-09-01

    PROCEEDINGS No.408 Flight Simulation DTIC !ELECTE NOVO505s ’ D -J DISTRIBUTION AND AVAILABILITY I I •k i nimy fle-"-- THE MISSION OF AGARI) The mission of...recherche. Ie d ~veloppement et lentrainement. Les objectifs du symposium de la commmission m~canique de vol de L’AGARD 6taient de fournir une description...tttbution Availjbiily CcodeS AvailI a.- d or Dist Spe~cial FLIGHT MECHANICS PANEL OFFICERS Chairman: Dr Ing. P.Hamcl Deputy Chairman: Dr Ing. A.Filisetti

  3. Hybrid Simulator

    SciTech Connect

    Trujillo, David J.; Sridharan, Srikesh; Weinstock, Irvin

    2005-10-15

    HybSim (short for Hybrid Simulator) is a flexible, easy to use screening tool that allows the user to quanti the technical and economic benefits of installing a village hybrid generating system and simulates systems with any combination of —Diesel generator sets —Photovoltaic arrays -Wind Turbines and -Battery energy storage systems Most village systems (or small population sites such as villages, remote military bases, small communities, independent or isolated buildings or centers) depend on diesel generation systems for their source of energy. HybSim allows the user to determine other "sources" of energy that can greatly reduce the dollar to kilo-watt hour ratio. Supported by the DOE, Energy Storage Program, HybSim was initially developed to help analyze the benefits of energy storage systems in Alaskan villages. Soon after its development, other sources of energy were added providing the user with a greater range of analysis opportunities and providing the village with potentially added savings. In addition to village systems, HybSim has generated interest for use from military institutions in energy provisions and USAID for international village analysis.

  4. Neuromechanical Simulation

    PubMed Central

    Edwards, Donald H.

    2010-01-01

    The importance of the interaction between the body and the brain for the control of behavior has been recognized in recent years with the advent of neuromechanics, a field in which the coupling between neural and biomechanical processes is an explicit focus. A major tool used in neuromechanics is simulation, which connects computational models of neural circuits to models of an animal's body situated in a virtual physical world. This connection closes the feedback loop that links the brain, the body, and the world through sensory stimuli, muscle contractions, and body movement. Neuromechanical simulations enable investigators to explore the dynamical relationships between the brain, the body, and the world in ways that are difficult or impossible through experiment alone. Studies in a variety of animals have permitted the analysis of extremely complex and dynamic neuromechanical systems, they have demonstrated that the nervous system functions synergistically with the mechanical properties of the body, they have examined hypotheses that are difficult to test experimentally, and they have explored the role of sensory feedback in controlling complex mechanical systems with many degrees of freedom. Each of these studies confronts a common set of questions: (i) how to abstract key features of the body, the world and the CNS in a useful model, (ii) how to ground model parameters in experimental reality, (iii) how to optimize the model and identify points of sensitivity and insensitivity, and (iv) how to share neuromechanical models for examination, testing, and extension by others. PMID:20700384

  5. Introduction to Quantum Simulation

    NASA Technical Reports Server (NTRS)

    Williams, Colin P.

    2005-01-01

    This viewgraph presentation addresses the problem of efficiently simulating the evolution of a quantum system. The contents include: 1) Quantum Simulation; 2) Extracting Answers from Quantum Simulations; 3) Quantum Fourier Transform; 4) Eigenvalue Estimation; 5) Fermionic Simulations.

  6. Simulated Breeding

    NASA Astrophysics Data System (ADS)

    Unemi, Tatsuo

    This chapter describes a basic framework of simulated breeding, a type of interactive evolutionary computing to breed artifacts, whose origin is Blind Watchmaker by Dawkins. These methods make it easy for humans to design a complex object adapted to his/her subjective criteria, just similarly to agricultural products we have been developing over thousands of years. Starting from randomly initialized genome, the solution candidates are improved through several generations with artificial selection. The graphical user interface helps the process of breeding with techniques of multifield user interface and partial breeding. The former improves the diversity of individuals that prevents being trapped at local optimum. The latter makes it possible for the user to fix features he/she already satisfied. These methods were examined through artistic applications by the author: SBART for graphics art and SBEAT for music. Combining with a direct genome editor and exportation to another graphical or musical tool on the computer, they can be powerful tools for artistic creation. These systems may contribute to the creation of a type of new culture.

  7. Software simulator for multiple computer simulation system

    NASA Technical Reports Server (NTRS)

    Ogrady, E. P.

    1983-01-01

    A description is given of the structure and use of a computer program that simulates the operation of a parallel processor simulation system. The program is part of an investigation to determine algorithms that are suitable for simulating continous systems on a parallel processor configuration. The simulator is designed to accurately simulate the problem-solving phase of a simulation study. Care has been taken to ensure the integrity and correctness of data exchanges and to correctly sequence periods of computation and periods of data exchange. It is pointed out that the functions performed during a problem-setup phase or a reset phase are not simulated. In particular, there is no attempt to simulate the downloading process that loads object code into the local, transfer, and mapping memories of processing elements or the memories of the run control processor and the system control processor. The main program of the simulator carries out some problem-setup functions of the system control processor in that it requests the user to enter values for simulation system parameters and problem parameters. The method by which these values are transferred to the other processors, however, is not simulated.

  8. COCOA: Simulating Observations of Star Cluster Simulations

    NASA Astrophysics Data System (ADS)

    Askar, Abbas; Giersz, Mirek; Pych, Wojciech; Dalessandro, Emanuele

    2017-03-01

    COCOA (Cluster simulatiOn Comparison with ObservAtions) creates idealized mock photometric observations using results from numerical simulations of star cluster evolution. COCOA is able to present the output of realistic numerical simulations of star clusters carried out using Monte Carlo or N-body codes in a way that is useful for direct comparison with photometric observations. The code can simulate optical observations from simulation snapshots in which positions and magnitudes of objects are known. The parameters for simulating the observations can be adjusted to mimic telescopes of various sizes. COCOA also has a photometry pipeline that can use standalone versions of DAOPHOT (ascl:1104.011) and ALLSTAR to produce photometric catalogs for all observed stars.

  9. Metabolic simulation chamber

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G.; Hendricks, C. M.

    1972-01-01

    Metabolic simulation combustion chamber was developed as subsystem for breathing metabolic simulator. Entire system is used for evaluation of life support and resuscitation equipment. Metabolism subsystem simulates a human by consuming oxygen and producing carbon dioxide. Basic function is to simulate human metabolic range from rest to hard work.

  10. Systems Engineering Simulator (SES) Simulator Planning Guide

    NASA Technical Reports Server (NTRS)

    McFarlane, Michael

    2011-01-01

    The simulation process, milestones and inputs are unknowns to first-time users of the SES. The Simulator Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their engineering personnel in simulation planning and execution. Material covered includes a roadmap of the simulation process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, facility interfaces, and inputs necessary to define scope, cost, and schedule are included as an appendix to the guide.

  11. DSIM: A distributed simulator

    NASA Technical Reports Server (NTRS)

    Goswami, Kumar K.; Iyer, Ravishankar K.

    1990-01-01

    Discrete event-driven simulation makes it possible to model a computer system in detail. However, such simulation models can require a significant time to execute. This is especially true when modeling large parallel or distributed systems containing many processors and a complex communication network. One solution is to distribute the simulation over several processors. If enough parallelism is achieved, large simulation models can be efficiently executed. This study proposes a distributed simulator called DSIM which can run on various architectures. A simulated test environment is used to verify and characterize the performance of DSIM. The results of the experiments indicate that speedup is application-dependent and, in DSIM's case, is also dependent on how the simulation model is distributed among the processors. Furthermore, the experiments reveal that the communication overhead of ethernet-based distributed systems makes it difficult to achieve reasonable speedup unless the simulation model is computation bound.

  12. Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Rendezvous Docking Simulator. The simulation demonstrated linear and gimbal motions of the capsule and a Gemini-Agena docking. [Entire movie available on DVD from CASI as Doc ID 20070030983. Contact help@sti.nasa.gov

  13. Electronic Driver Education Simulator.

    ERIC Educational Resources Information Center

    Spence, Keith R.

    1980-01-01

    Describes the collision avoidance simulator, which provides both a hands-on prolect for digital electronics students and a motivation device for driver education students. Gives details of the electrical construction and operation of the simulator. (JOW)

  14. Distribution system simulator

    NASA Technical Reports Server (NTRS)

    Bahrami, K. A.; Kirkham, H.; Rahman, S.

    1986-01-01

    In a series of tests performed under the Department of Energy auspices, power line carrier propagation was observed to be anomalous under certain circumstances. To investigate the cause, a distribution system simulator was constructed. The simulator was a physical simulator that accurately represented the distribution system from below power frequency to above 50 kHz. Effects such as phase-to-phase coupling and skin effect were modeled. Construction details of the simulator, and experimental results from its use are presented.

  15. Remote manipulator dynamic simulation

    NASA Technical Reports Server (NTRS)

    Wild, E. C.; Donges, P. K.; Garand, W. A.

    1972-01-01

    A simulator to generate the real time visual scenes required to perform man in the loop investigations of remote manipulator application and design concepts for the space shuttle is described. The simulated remote manipulator consists of a computed display system that uses a digital computer, the electronic scene generator, an operator's station, and associated interface hardware. A description of the capabilities of the implemented simulation is presented. The mathematical models and programs developed for the simulation are included.

  16. Microgravity Simulation Facility (MSF)

    NASA Technical Reports Server (NTRS)

    Richards, Stephanie E. (Compiler); Levine, Howard G.; Zhang, Ye

    2016-01-01

    The Microgravity Simulator Facility (MSF) at Kennedy Space Center (KSC) was established to support visiting scientists for short duration studies utilizing a variety of microgravity simulator devices that negate the directional influence of the "g" vector (providing simulated conditions of micro or partial gravity). KSC gravity simulators can be accommodated within controlled environment chambers allowing investigators to customize and monitor environmental conditions such as temperature, humidity, CO2, and light exposure.

  17. Test vs. simulation

    NASA Technical Reports Server (NTRS)

    Wood, Charles C.

    1991-01-01

    The following topics are presented in tabular form: (1) simulation capability assessments (no propulsion system test); (2) advanced vehicle simulation capability assessment; (3) systems tests identified events; (4) main propulsion test article (MPTA) testing evaluation; (5) Saturn 5, 1B, and 1 testing evaluation. Special vehicle simulation issues that are propulsion related are briefly addressed.

  18. Air Combat Simulator

    NASA Technical Reports Server (NTRS)

    1981-01-01

    By adapting COSMIC's One-on-One Adaptive Maneuvering Logic (AML) for two versus one simulation, Link Division was able to reduce software and other design/development costs. Enhancements to the AML program developed by Link for simulation of two-versus one combat, two trainees can simultaneously engage a computer driven target, thereby doubling the training utility of the simulator.

  19. Digital Simulation in Education.

    ERIC Educational Resources Information Center

    Braun, Ludwig

    Simulation as a mode of computer use in instruction has been neglected by educators. This paper briefly explores the circumstances in which simulations are useful and presents several examples of simulation programs currently being used in high-school biology, chemistry, physics, and social studies classes. One program, STERIL, which simulates…

  20. Breathing metabolic simulator

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G., Jr.; Hendricks, C. M.; Morison, W. B.

    1972-01-01

    A description is given of an automatic computer controlled second generation breathing metabolic simulator (BMS). The simulator is used for evaluating and testing respiratory diagnostic, monitoring, support, and resuscitation equipment. Any desired sequence of metabolic activities can be simulated on the device for up to 15 hours. The computer monitors test procedures and provides printouts of test results.

  1. Simulation in Sport Finance

    ERIC Educational Resources Information Center

    Drayer, Joris; Rascher, Dan

    2010-01-01

    Simulations have long been used in business schools to give students experience making real-world decisions in a relatively low risk environment. The OAKLAND A'S BASEBALL BUSINESS SIMULATOR takes a traditional business simulation and applies it to the sport industry, in which sales of tangible products are replaced by sales of experiences provided…

  2. Conducting Effective Simulator Training.

    ERIC Educational Resources Information Center

    Gerling, Kenneth D.

    This paper describes the simulator phase of Commonwealth Edison's program for training and licensing operators of nuclear power stations. Topics covered include (1) preparing the students before starting the simulator phase; (2) the simulator schedule and the number of students that can be trained effectively in a class; (3) format and structure…

  3. NAPL: SIMULATOR DOCUMENTATION

    EPA Science Inventory

    A mathematical and numerical model is developed to simulate the transport and fate of NAPLs (Non-Aqueous Phase Liquids) in near-surface granular soils. The resulting three-dimensional, three phase simulator is called NAPL. The simulator accommodates three mobile phases: water, NA...

  4. CAISSON: Interconnect Network Simulator

    NASA Technical Reports Server (NTRS)

    Springer, Paul L.

    2006-01-01

    Cray response to HPCS initiative. Model future petaflop computer interconnect. Parallel discrete event simulation techniques for large scale network simulation. Built on WarpIV engine. Run on laptop and Altix 3000. Can be sized up to 1000 simulated nodes per host node. Good parallel scaling characteristics. Flexible: multiple injectors, arbitration strategies, queue iterators, network topologies.

  5. Today's Business Simulation Industry

    ERIC Educational Resources Information Center

    Summers, Gary J.

    2004-01-01

    New technologies are transforming the business simulation industry. The technologies come from research in computational fields of science, and they endow simulations with new capabilities and qualities. These capabilities and qualities include computerized behavioral simulations, online feedback and coaching, advanced interfaces, learning on…

  6. Weld arc simulator

    DOEpatents

    Burr, Melvin J.

    1990-01-30

    An arc voltage simulator for an arc welder permits the welder response to a variation in arc voltage to be standardized. The simulator uses a linear potentiometer connected to the electrode to provide a simulated arc voltage at the electrode that changes as a function of electrode position.

  7. Simulations. ELT Guide 2.

    ERIC Educational Resources Information Center

    Herbert, David; Sturtridge, Gill

    Simulation, including role-playing and role-simulation, as techniques for teaching English as a second language are discussed and illustrated. Introductory sections outline the instructional value of simulations, their motivating function, stages in their production, and their structure. Their production includes these stages: analysis of student…

  8. Simulating Supernova Light Curves

    SciTech Connect

    Even, Wesley Paul; Dolence, Joshua C.

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  9. Electrical Circuit Simulation Code

    SciTech Connect

    Wix, Steven D.; Waters, Arlon J.; Shirley, David

    2001-08-09

    Massively-Parallel Electrical Circuit Simulation Code. CHILESPICE is a massively-arallel distributed-memory electrical circuit simulation tool that contains many enhanced radiation, time-based, and thermal features and models. Large scale electronic circuit simulation. Shared memory, parallel processing, enhance convergence. Sandia specific device models.

  10. Air Shower Simulations

    SciTech Connect

    Alania, Marco; Gomez, Adolfo V. Chamorro; Araya, Ignacio J.; Huerta, Humberto Martinez; Flores, Alejandra Parra; Knapp, Johannes

    2009-04-30

    Air shower simulations are a vital part of the design of air shower experiments and the analysis of their data. We describe the basic features of air showers and explain why numerical simulations are the appropriate approach to model the shower simulation. The CORSIKA program, the standard simulation program in this field, is introduced and its features, performance and limitations are discussed. The basic principles of hadronic interaction models and some gerneral simulation techniques are explained. Also a brief introduction to the installation and use of CORSIKA is given.

  11. Advanced electromagnetic gun simulation

    NASA Astrophysics Data System (ADS)

    Brown, J. L.; George, E. B.; Lippert, J. R.; Balius, A. R.

    1986-11-01

    The architecture, software and application of a simulation system for evaluating electromagnetic gun (EMG) operability, maintainability, test data and performance tradeoffs are described. The system features a generic preprocessor designed for handling the large data rates necessary for EMG simulations. The preprocessor and postprocessor operate independent of the EMG simulation, which is viewed through windows by the user, who can then select the areas of the simulation desired. The simulation considers a homopolar generator, busbars, pulse shaping coils, the barrel, switches, and prime movers. In particular, account is taken of barrel loading by the magnetic field, Lorentz force and plasma pressure.

  12. Computer simulation of bulk and surface chemical diffusion of light atoms in metals

    SciTech Connect

    Murch, G.E.

    1981-01-01

    The lattice gas as a model for interstitial solid solution and adsorption systems is reviewed with emphasis on the generation of ordered structures. Then, as a prelude to the main discourse on chemical diffusion, the tracer diffusion coefficient is discussed in conjunction with the presentation of Monte Carlo results. Next, chemical diffusion is treated in detail with emphasis on the Danken equation. Monte Carlo results are then presented for the chemical diffusion coefficient. The large maximum in the chemical diffusivity observed within the ordered phase is traced back to the very strong driving force provided by the chemical potential derivative.

  13. Simulation in laparoscopic surgery.

    PubMed

    León Ferrufino, Felipe; Varas Cohen, Julián; Buckel Schaffner, Erwin; Crovari Eulufi, Fernando; Pimentel Müller, Fernando; Martínez Castillo, Jorge; Jarufe Cassis, Nicolás; Boza Wilson, Camilo

    2015-01-01

    Nowadays surgical trainees are faced with a more reduced surgical practice, due to legal limitations and work hourly constraints. Also, currently surgeons are expected to dominate more complex techniques such as laparoscopy. Simulation emerges as a complementary learning tool in laparoscopic surgery, by training in a safe, controlled and standardized environment, without jeopardizing patient' safety. Simulation' objective is that the skills acquired should be transferred to the operating room, allowing reduction of learning curves. The use of simulation has increased worldwide, becoming an important tool in different surgical residency programs and laparoscopic training courses. For several countries, the approval of these training courses are a prerequisite for the acquisition of surgeon title certifications. This article reviews the most important aspects of simulation in laparoscopic surgery, including the most used simulators and training programs, as well as the learning methodologies and the different key ways to assess learning in simulation.

  14. Parallel Atomistic Simulations

    SciTech Connect

    HEFFELFINGER,GRANT S.

    2000-01-18

    Algorithms developed to enable the use of atomistic molecular simulation methods with parallel computers are reviewed. Methods appropriate for bonded as well as non-bonded (and charged) interactions are included. While strategies for obtaining parallel molecular simulations have been developed for the full variety of atomistic simulation methods, molecular dynamics and Monte Carlo have received the most attention. Three main types of parallel molecular dynamics simulations have been developed, the replicated data decomposition, the spatial decomposition, and the force decomposition. For Monte Carlo simulations, parallel algorithms have been developed which can be divided into two categories, those which require a modified Markov chain and those which do not. Parallel algorithms developed for other simulation methods such as Gibbs ensemble Monte Carlo, grand canonical molecular dynamics, and Monte Carlo methods for protein structure determination are also reviewed and issues such as how to measure parallel efficiency, especially in the case of parallel Monte Carlo algorithms with modified Markov chains are discussed.

  15. Instrumented Architectural Simulation System

    NASA Technical Reports Server (NTRS)

    Delagi, B. A.; Saraiya, N.; Nishimura, S.; Byrd, G.

    1987-01-01

    Simulation of systems at an architectural level can offer an effective way to study critical design choices if (1) the performance of the simulator is adequate to examine designs executing significant code bodies, not just toy problems or small application fragements, (2) the details of the simulation include the critical details of the design, (3) the view of the design presented by the simulator instrumentation leads to useful insights on the problems with the design, and (4) there is enough flexibility in the simulation system so that the asking of unplanned questions is not suppressed by the weight of the mechanics involved in making changes either in the design or its measurement. A simulation system with these goals is described together with the approach to its implementation. Its application to the study of a particular class of multiprocessor hardware system architectures is illustrated.

  16. Simulation integration with confidence

    NASA Astrophysics Data System (ADS)

    Strelich, Tom; Stalcup, Bruce W.

    1999-07-01

    Current financial, schedule and risk constraints mandate reuse of software components when building large-scale simulations. While integration of simulation components into larger systems is a well-understood process, it is extremely difficult to do while ensuring that the results are correct. Illgen Simulation Technologies Incorporated and Litton PRC have joined forces to provide tools to integrate simulations with confidence. Illgen Simulation Technologies has developed an extensible and scaleable, n-tier, client- server, distributed software framework for integrating legacy simulations, models, tools, utilities, and databases. By utilizing the Internet, Java, and the Common Object Request Brokering Architecture as the core implementation technologies, the framework provides built-in scalability and extensibility.

  17. Robotic surgical simulation.

    PubMed

    Liss, Michael A; McDougall, Elspeth M

    2013-01-01

    Robotic surgery has undergone exponential growth and has ever developing utilization. The explosion of new technologies and regulation have led to challenges in training surgeons who desire this skill set. We review the current state of robotic simulation and incorporation of simulation into surgical training curricula. In addition to the literature review, results of a questionnaire survey study of 21 expert and novice surgeons attending a Urologic Robotic Oncology conference using 3 different robotic skill simulation devices are discussed. An increasing number of robotic surgery simulators have had some degree of validation study of their use in surgical education curricula and proficiency testing. Although simulators are advantageous, confirmation of construct and predictive validity of robotic simulators and their reliability as a training tool will be necessary before they are integrated into the surgical credentialing process.

  18. Simulator of Road Tunnel

    NASA Astrophysics Data System (ADS)

    Danišovič, Peter; Schlosser, František; Šrámek, Juraj; Rázga, Martin

    2015-05-01

    A Tunnel Traffic & Operation Simulator is a device of the Centre of Transport Research at the University of Žilina. The Simulator allows managing technological equipment of virtual two-tube highway tunnel, which is interconnected with simulation of vehicle traffic in tunnel. Changes of the traffic-operation states and other equipment are reflecting at the simulated traffic, as well as simulations of various emergency events in traffic initiate changes in tunnel detecting and measuring devices. It is thus possible to simulate emergency states, which can be affected by various faults of technology as well as by climatic conditions. The solutions can be found in irreplaceable experiences of Slovak road tunnel operators, changes of trafficoperation states, visualizations of operator technological display screens, technological devices labelling in order to increase operational safety of road tunnels.

  19. Solar heat pump simulator

    NASA Astrophysics Data System (ADS)

    Catan, M. A.

    A simulator was utilized to provide controlled-temperature sources and sinks to an experimental water-to-water laboratory heat pump test bed. This combination was used to demonstrate and explore the potential of the vapor-compression cycle to deliver high COP's at SAHP source temperatures. Results from the simulator were used in computer simulations of complete systems performed by BNL, by the SAHP contractors, and by others. A two-speed compressor was first tested at high source temperatures on the BNL simulator. In view of the decision by both contractors to construct water-to-air (rather than water-to-water) heat pumps, the BNL simulator was fitted with an air-side test loop. The prototype heat pump was tested under steady-state conditions on the BNL simulator.

  20. Simulation in Health Sciences Education.

    ERIC Educational Resources Information Center

    Norman, Geoffrey R.; And Others

    1985-01-01

    Reviews five simulation methods used in medical and health science education: oral examinations, live simulated patients, mannequins, and written and computer-based simulations. Each type of simulation is discussed relative to its fidelity, reliability, validity, learning, and feasibility. (MBR)

  1. The Sandia Lightning Simulator.

    SciTech Connect

    Martinez, Leonard E.; Caldwell, Michele

    2005-01-01

    The Sandia Lightning Simulator at Sandia National Laboratories can provide up to 200 kA for a simulated single lightning stroke, 100 kA for a subsequent stroke, and hundreds of Amperes of continuing current. It has recently been recommissioned after a decade of inactivity and the single-stroke capability demonstrated. The simulator capabilities, basic design components, upgrades, and diagnostic capabilities are discussed in this paper.

  2. Nanoelectronic Device Simulator Nanodev

    NASA Astrophysics Data System (ADS)

    Novik, E. G.; Sheremet, I. V.; Ivashkevich, S. S.; Abramov, I. I.

    In this paper the models for simulation of single-electron (Coulomb blockade) and resonant tunneling structures are described. To calculate various parameters and characteristics (current-voltage characteristics, parameters of operation and others) of these structures algorithms and programs have been developed. The simulator NANODEV consists of two modeling units for Coulomb blockade and for resonant tunneling devices. Some calculation results are also present. The simulator was developed for PC computers.

  3. NPS AUV Integrated Simulator

    DTIC Science & Technology

    1992-03-01

    147 3. GRAPHIC OBJECT MODEI’QUSING OBJECTFILE FORMAT (cIF)...................... ........... 149. APPENDIX -C. NPS, AUV SONAR CLASSIFICATION SYSTEM...Monterey Bay .. 15 Figure 2.8 Graphics simulation for NPS AUV sonar visualization .......... 15’ Figure 3.1 Integrated simulator network physical...3.11 Integrated simulation display of AUV minefield searh ........ 39 Figure4.1 NPS AUV sonar beam profiles in the NPS pool .......... 43 Figure 42 NPS

  4. Bridge Crossing Simulator

    DTIC Science & Technology

    2014-10-07

    reaction structure, and a control system, the BCS physically simulates vehicular crossing loads for the expected life span of the bridge undergoing...information provided by the customer. In general, statics will be used to determine equations for moments and deflections based on the specific bridge ...systems. Through the use of hydraulic actuators, a reaction structure, and a control system, the Bridge Crossing Simulator physically simulates vehicular

  5. A photovoltaic array simulator

    NASA Astrophysics Data System (ADS)

    Vachtsevanos, G. J.; Grimbas, E. J.

    A system simulating the output voltage-current characteristics of a photovoltaic array is described. The simulator may be used to test the performance of PV arrays and associated power conditioning equipment necessary for the autonomous or interconnected operation of photovoltaic energy sources. The simulator's main features include simplicity of construction, wide parametric variability and low cost. It is capable of reproducing the output characteristics of commercially available arrays at varying solar irradiation levels with sufficient accuracy. The design ensures the lowest possible power dissipation and minimal thermal drift. It is estimated that the cost of the simulator is an insignificant fraction of the actual array cost in the kilowatt power range.

  6. Helicopter simulator standards

    NASA Technical Reports Server (NTRS)

    Boothe, Edward M.

    1992-01-01

    The initial advisory circular was produced in 1984 (AC 120-XX). It was not finalized, however, because the FAR's for pilot certification did not recognize helicopter simulators and, therefore, permitted no credit for their use. That is being rectified, and, when the new rules are published, standards must be available for qualifying simulators. Because of the lack of a data base to support specification of these standards, the FAA must rely on the knowledge of experts in the simulator/training industry. A major aim of this workshop is to form a working group of these experts to produce a set of standards for helicopter training simulators.

  7. Aviation Safety Simulation Model

    NASA Technical Reports Server (NTRS)

    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.

  8. Reality versus Simulation

    ERIC Educational Resources Information Center

    Srinivasan, Srilekha; Perez, Lance C.; Palmer, Robert D.; Brooks, David W.; Wilson, Kathleen; Fowler, David

    2006-01-01

    A systematic study of the implementation of simulation hardware (TIMS) replacing software (MATLAB) was undertaken for advanced undergraduate and early graduate courses in electrical engineering. One outcome of the qualitative component of the study was remarkable: most students interviewed (4/4 and 6/9) perceived the software simulations as…

  9. Political Simulations Using Excel

    ERIC Educational Resources Information Center

    Jackson, Steven F.

    2013-01-01

    Simulations have received considerable attention as a tool to promote problem-solving skills, intense involvement, and high-order thinking among students. Whether semester-long exercises or a single-class session, simulations are often used in areas of conflict studies, diplomatic studies, trade disputes, electoral processes, and policy and legal…

  10. Radiation detector spectrum simulator

    DOEpatents

    Wolf, M.A.; Crowell, J.M.

    1985-04-09

    A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  11. Radiation detector spectrum simulator

    DOEpatents

    Wolf, Michael A.; Crowell, John M.

    1987-01-01

    A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.

  12. Simulating Ordinal Data

    ERIC Educational Resources Information Center

    Ferrari, Pier Alda; Barbiero, Alessandro

    2012-01-01

    The increasing use of ordinal variables in different fields has led to the introduction of new statistical methods for their analysis. The performance of these methods needs to be investigated under a number of experimental conditions. Procedures to simulate from ordinal variables are then required. In this article, we deal with simulation from…

  13. Damselfly Network Simulator

    SciTech Connect

    2014-04-01

    Damselfly is a model-based parallel network simulator. It can simulate communication patterns of High Performance Computing applications on different network topologies. It outputs steady-state network traffic for a communication pattern, which can help in studying network congestion and its impact on performance.

  14. Simulation: What Is It?

    ERIC Educational Resources Information Center

    Laktasic, Stanley G.

    Simulation is the duplication of the essential characteristics of a task or situation. It represents three elements of the teaching-learning process: (1) stimulus situation; (2) response; and (3) feedback. The uses of simulation may fall into one of three general categories: research--the generation of information about an operational or proposed…

  15. Multicore Education through Simulation

    ERIC Educational Resources Information Center

    Ozturk, O.

    2011-01-01

    A project-oriented course for advanced undergraduate and graduate students is described for simulating multiple processor cores. Simics, a free simulator for academia, was utilized to enable students to explore computer architecture, operating systems, and hardware/software cosimulation. Motivation for including this course in the curriculum is…

  16. Simulating Price-Taking

    ERIC Educational Resources Information Center

    Engelhardt, Lucas M.

    2015-01-01

    In this article, the author presents a price-takers' market simulation geared toward principles-level students. This simulation demonstrates that price-taking behavior is a natural result of the conditions that create perfect competition. In trials, there is a significant degree of price convergence in just three or four rounds. Students find this…

  17. Electric-car simulation

    NASA Technical Reports Server (NTRS)

    Chapman, C. P.; Slusser, R. A.

    1980-01-01

    PARAMET, interactive simulation program for parametric studies of electric vehicles, guides user through simulation by menu and series of prompts for input parameters. Program considers aerodynamic drag, rolling resistance, linear and rotational acceleration, and road gradient as forces acting on vehicle.

  18. Assessment in Simulations

    ERIC Educational Resources Information Center

    Raymond, Chad; Usherwood, Simon

    2013-01-01

    Simulations are employed widely as teaching tools in political science, yet evidence of their pedagogical effectiveness, in comparison to other methods of instruction, is mixed. The assessment of learning outcomes is often a secondary concern in simulation design, and the qualitative and quantitative methods used to evaluate outcomes are…

  19. Airblast Simulator Studies.

    DTIC Science & Technology

    1984-02-01

    predicted in steady state theory . 0 The Army has decided on the basis of other arguments that 10% blockage is acceptable for a large blast simulator. These...Proceedings, 28-30 April 1965, p. 259. 16. Sanal , M4., Lindberg, H.E. and Colton, J.D., "Simulation of Blast Waves with Tailored Explosive Charges", SRI

  20. TANGO Array.. 2. Simulations

    NASA Astrophysics Data System (ADS)

    Bauleo, P.; Bonifazi, C.; Filevich, A.

    2004-01-01

    The angular and energy resolutions of the TANGO Array were obtained using extensive Monte Carlo simulations performed with a double purpose: (1) to determine the appropriate parameters for the array fitting to the desired range of sensitivity (the knee energy region), and (2) to construct a reliable shower database required for reference in the analysis of experimental data. The AIRES code, with the SIBYLL hadronic collision package, was used to simulate Extended Air Showers produced by primary cosmic rays (assuming protons and iron nuclei), with energies ranging from 10 14 to 10 18 eV. These data were fed into a realistic code which simulates the response of the detectors (water Cherenkov detectors), including the electronics, pickup noise, and the signal attenuation in the connecting cables. The trigger stage was considered in the simulations in order to estimate the trigger efficiency of the array and to verify the accuracy of the reconstruction codes. This paper delineates the simulations performed to obtain the expected behavior of the array, and describes the simulated data. The results of these simulations suggest that we can expect an error in the energy of the primary cosmic-ray of ˜60% of the estimated value and that the error in the measurement of the direction of arrival can be estimated as ˜4°. The present simulations also indicate that unambiguous assignments of the primary energy cannot be obtained because of the uncertainty in the nature of the primary cosmic ray.

  1. Breathing-metabolic simulator

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G.; Hendricks, C. M.; Morison, W. B.

    1972-01-01

    Breathing-metabolic simulator was developed to be used for evaluation of life support equipment. Apparatus simulates human breathing rate and controls temperature and humidity of exhaled air as well as its chemical composition. All functions are designed to correspond to various degrees of human response.

  2. Parallel Lisp simulator

    SciTech Connect

    Weening, J.S.

    1988-05-01

    CSIM is a simulator for parallel Lisp, based on a continuation passing interpreter. It models a shared-memory multiprocessor executing programs written in Common Lisp, extended with several primitives for creating and controlling processes. This paper describes the structure of the simulator, measures its performance, and gives an example of its use with a parallel Lisp program.

  3. Dragon Missile Simulator.

    DTIC Science & Technology

    1978-02-01

    A brassboard training device that simulates the Dragon missile was developed and tested to evaluate the characteristics that are necessary for...improved training of Dragon gunners. Videotape recording and a full color simulation were found to be valuable as a training aid. An audible signal

  4. Prototyping distributed simulation networks

    NASA Technical Reports Server (NTRS)

    Doubleday, Dennis L.

    1990-01-01

    Durra is a declarative language designed to support application-level programming. The use of Durra is illustrated to describe a simple distributed application: a simulation of a collection of networked vehicle simulators. It is shown how the language is used to describe the application, its components and structure, and how the runtime executive provides for the execution of the application.

  5. Simulating Laboratory Procedures.

    ERIC Educational Resources Information Center

    Baker, J. E.; And Others

    1986-01-01

    Describes the use of computer assisted instruction in a medical microbiology course. Presents examples of how computer assisted instruction can present case histories in which the laboratory procedures are simulated. Discusses an authoring system used to prepare computer simulations and provides one example of a case history dealing with fractured…

  6. Radio Channel Simulator (RCSM)

    SciTech Connect

    2007-01-31

    This is a simulation package for making site specific predictions of radio signal strength. The software computes received power at discrete grid points as a function of the transmitter location and propagation environment. It is intended for use with wireless network simulation packages and to support wireless network deployments.

  7. Beyond Iconic Simulation

    ERIC Educational Resources Information Center

    Dormans, Joris

    2011-01-01

    Realism remains a prominent topic in game design and industry research; yet, a strong academic case can be made that games are anything, but realistic. This article frames realism in games in semiotic terms as iconic simulation and argues that games can gain expressiveness when they move beyond the current focus on iconic simulation. In parallel…

  8. VCSEL Applications and Simulation

    NASA Technical Reports Server (NTRS)

    Cheung, Samson; Goorjian, Peter; Ning, Cun-Zheng; Li, Jian-Zhong

    2000-01-01

    This viewgraph presentation gives an overview of Vertical Cavity Surface Emitting Laser (VCSEL) simulation and its applications. Details are given on the optical interconnection in information technology of VCSEL, the formulation of the simulation, its numeric algorithm, and the computational results.

  9. Simulation Games in Learning.

    ERIC Educational Resources Information Center

    Boocock, Sarane S., Ed.; Schild, E.O., Ed.

    Simulation games serve many functions, but the important one to educators is that they present the student player with a real-life situation allowing him to use his knowledge and abilities while discovering decision-making skills for himself. To provide a basic reference on simulation gaming, essays on various aspects of games were collected from…

  10. Simulation: An Overview.

    ERIC Educational Resources Information Center

    Twelker, Paul A.

    Simulation may be defined as (1) a technique of modeling (physically, iconically, verbally, or mathematically) some aspects of a real or proposed system, process, or environment or (2) the model (physical, iconic, verbal, or mathematical) of some aspects of a real or proposed system, process, or environment. Simulation may be used to generate…

  11. MRDIS Simulation Software

    SciTech Connect

    Pete Humphrey, Charles Babb

    2012-01-05

    The MRDIS Simulator is a software application to duplicate the tcp/ip output normally produced by a Mobile Radiation Detection and Identification System (MRDIS) radiation detector. Output simulates the data stream from TSA radiation detectors plus OCR data from AsiaVision OCR systems (used by the actual MRDIS).

  12. Quantum simulated annealing

    NASA Astrophysics Data System (ADS)

    Boixo, Sergio; Somma, Rolando; Barnum, Howard

    2008-03-01

    We develop a quantum algorithm to solve combinatorial optimization problems through quantum simulation of a classical annealing process. Our algorithm combines techniques from quantum walks and quantum phase estimation, and can be viewed as the quantum analogue of the discrete-time Markov Chain Monte Carlo implementation of classical simulated annealing.

  13. Rehearsal Enabling Simulation Technologies

    DTIC Science & Technology

    2011-03-01

    developed by Renaissance Sciences Corporation (RSC) in collaboration with Elmendorf Civil Engineering, Joint Pacific Area Range Complex (JPARC) management...from the Air Force Combat Climatology Center (AFCCC) into Expert Common Immersive Theatre Environment (XCITE) threat simulations. AFCCC created an...L-3 Communications Link Simulation and Training, and Renaissance Science Corporation. The team provided as needed consultation to numerous

  14. Simulator Tests Controller Performance

    NASA Technical Reports Server (NTRS)

    Lembeck, M. F.; Rasmussen, R. D.

    1986-01-01

    Compact servosystem applies simulated dynamic loads, enabling realistic appraisal of motor and its control system without inconvenience of attaching real load. System simulates moments of inertia, rotational vibrations, changing load torques, and other characteristics of large or complex loads, without loads themselves and without awkwardness (and inaccuracy) of gravity-compensating devices used with such loads.

  15. Simulation. [SITE 2001 Section].

    ERIC Educational Resources Information Center

    Seymour, Cathy R., Ed.

    This document contains three papers on simulation from the SITE (Society for Information Technology & Teacher Education) 2001 conference. "Simulations in the Learning Cycle: A Case Study Involving 'Exploring the Nardoo'" (William M. Dwyer and Valesca E. Lopez) presents a study of middle school students using a CD-based simulation…

  16. Parallel simulation today

    NASA Technical Reports Server (NTRS)

    Nicol, David; Fujimoto, Richard

    1992-01-01

    This paper surveys topics that presently define the state of the art in parallel simulation. Included in the tutorial are discussions on new protocols, mathematical performance analysis, time parallelism, hardware support for parallel simulation, load balancing algorithms, and dynamic memory management for optimistic synchronization.

  17. Rainfall simulation in education

    NASA Astrophysics Data System (ADS)

    Peters, Piet; Baartman, Jantiene; Gooren, Harm; Keesstra, Saskia

    2016-04-01

    Rainfall simulation has become an important method for the assessment of soil erosion and soil hydrological processes. For students, rainfall simulation offers an year-round, attractive and active way of experiencing water erosion, while not being dependent on (outdoors) weather conditions. Moreover, using rainfall simulation devices, they can play around with different conditions, including rainfall duration, intensity, soil type, soil cover, soil and water conservation measures, etc. and evaluate their effect on erosion and sediment transport. Rainfall simulators differ in design and scale. At Wageningen University, both BSc and MSc student of the curriculum 'International Land and Water Management' work with different types of rainfall simulation devices in three courses: - A mini rainfall simulator (0.0625m2) is used in the BSc level course 'Introduction to Land Degradation and Remediation'. Groups of students take the mini rainfall simulator with them to a nearby field location and test it for different soil types, varying from clay to more sandy, slope angles and vegetation or litter cover. The groups decide among themselves which factors they want to test and they compare their results and discuss advantage and disadvantage of the mini-rainfall simulator. - A medium sized rainfall simulator (0.238 m2) is used in the MSc level course 'Sustainable Land and Water Management', which is a field practical in Eastern Spain. In this course, a group of students has to develop their own research project and design their field measurement campaign using the transportable rainfall simulator. - Wageningen University has its own large rainfall simulation laboratory, in which a 15 m2 rainfall simulation facility is available for research. In the BSc level course 'Land and Water Engineering' Student groups will build slopes in the rainfall simulator in specially prepared containers. Aim is to experience the behaviour of different soil types or slope angles when (heavy) rain

  18. Trick Simulation Environment 07

    NASA Technical Reports Server (NTRS)

    Lin, Alexander S.; Penn, John M.

    2012-01-01

    The Trick Simulation Environment is a generic simulation toolkit used for constructing and running simulations. This release includes a Monte Carlo analysis simulation framework and a data analysis package. It produces all auto documentation in XML. Also, the software is capable of inserting a malfunction at any point during the simulation. Trick 07 adds variable server output options and error messaging and is capable of using and manipulating wide characters for international support. Wide character strings are available as a fundamental type for variables processed by Trick. A Trick Monte Carlo simulation uses a statistically generated, or predetermined, set of inputs to iteratively drive the simulation. Also, there is a framework in place for optimization and solution finding where developers may iteratively modify the inputs per run based on some analysis of the outputs. The data analysis package is capable of reading data from external simulation packages such as MATLAB and Octave, as well as the common comma-separated values (CSV) format used by Excel, without the use of external converters. The file formats for MATLAB and Octave were obtained from their documentation sets, and Trick maintains generic file readers for each format. XML tags store the fields in the Trick header comments. For header files, XML tags for structures and enumerations, and the members within are stored in the auto documentation. For source code files, XML tags for each function and the calling arguments are stored in the auto documentation. When a simulation is built, a top level XML file, which includes all of the header and source code XML auto documentation files, is created in the simulation directory. Trick 07 provides an XML to TeX converter. The converter reads in header and source code XML documentation files and converts the data to TeX labels and tables suitable for inclusion in TeX documents. A malfunction insertion capability allows users to override the value of any

  19. Simulation in spinal diseases.

    PubMed

    Aso Escario, José; Martínez Quiñones, José Vicente; Aso Vizán, Alberto; Arregui Calvo, Ricardo; Bernal Lafuente, Marta; Alcázar Crevillén, Andrés

    2014-01-01

    Simulation is frequent in spinal disease, resulting in problems for specialists like Orthopedic Surgeons, Neurosurgeons, Reumathologists, etc. Simulation requires demonstration of the intentional production of false or exaggerated symptoms following an external incentive. The clinician has difficulties in demonstrating these criteria, resulting in misdiagnosis of simulation or misinterpretation of the normal patient as a simulator, with the possibility of iatrogenic distress and litigation. We review simulation-related problems in spine, proposing a terminological, as well as a diagnostic strategy including clinical and complementary diagnosis, as a way to avoid misinterpretation and minimize the iatrogenic distress and liability Based on the clinical-Forensic author's expertise, the literature is analyzed and the terminology readdressed to develop new terms (inconsistences, incongruences, discrepancies and contradictions). Clinical semiology and complementary test are adapted to the new scenario. Diagnostic strategy relies on anamnesis, clinical and complementary tests, adapting them to a uniform terminology with clear meaning of signs and symptoms.

  20. Star field simulator

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A Star Field Simulator has been developed to serve as a source of radiation for the ASTRO Star Tracker. The star tracker and simulator are components of a motion compensation test facility located at Marshall Space Flight Center in Huntsville, Alabama. Preflight tests and simulations using various levels of guide stars are performed in the test facility to establish performance of the motion compensation system before being used in a flight environment. The ASTRO Star Tracker operates over a wide dynamic range of irradiance corresponding to visual stellar magnitudes of -0.8 to 8. A minimum of three simulated guide stars with variable magnitudes are needed to fully test the Star Tracker performance under simulated mission conditions.

  1. Hardware Accelerated Simulated Radiography

    SciTech Connect

    Laney, D; Callahan, S; Max, N; Silva, C; Langer, S; Frank, R

    2005-04-12

    We present the application of hardware accelerated volume rendering algorithms to the simulation of radiographs as an aid to scientists designing experiments, validating simulation codes, and understanding experimental data. The techniques presented take advantage of 32 bit floating point texture capabilities to obtain validated solutions to the radiative transport equation for X-rays. An unsorted hexahedron projection algorithm is presented for curvilinear hexahedra that produces simulated radiographs in the absorption-only regime. A sorted tetrahedral projection algorithm is presented that simulates radiographs of emissive materials. We apply the tetrahedral projection algorithm to the simulation of experimental diagnostics for inertial confinement fusion experiments on a laser at the University of Rochester. We show that the hardware accelerated solution is faster than the current technique used by scientists.

  2. Simulation Interoperability (Interoperabilite de la simulation)

    DTIC Science & Technology

    2015-01-01

    knowledge derived through the scientific method. In NATO, S&T is addressed using different business models , namely a collaborative business model ...research and information exchange, and secondly an in-house delivery business model where S&T activities are conducted in a NATO dedicated executive...specialising in modelling and simulation, plus a Committee dedicated to supporting the information management needs of the organization. • AVT Applied Vehicle

  3. Simulating 'the right stuff'

    NASA Astrophysics Data System (ADS)

    Fischetti, M. A.; Truxal, C.

    1985-03-01

    The present investigation is mainly concerned with simulators employed in the training of pilots in the Armed Services and other military personnel, taking into account certain problems and approaches for overcoming them. The use of simulators for training programs has a number of advantages compared to training involving a use of the actual equipment. Questions arise, however, regarding the value of such a training. Thus, it has been said that, while simulators gave students practice in manual skill, they could not teach them to handle the stress of being in a real aircraft. It has also been argued that some tasks are not represented accurately enough for proper training. In response to this criticism, the capacity of the simulators has been greatly improved. However, this development leads to problems related to the cost of simulator training. Attention is given to better visuals for flight simulators, the current generation of graphics imagery and expected improvements, possibilities for reducing flight simulator costs, and advances due to progress in microcomputers.

  4. Embedding Quantum Simulator

    NASA Astrophysics Data System (ADS)

    di Candia, Roberto; Mejia, Bernabé; Castillo, Hernan; Simon Pedernales, Julen; Casanova, Jorge; Solano, Enrique

    2014-03-01

    We introduce the concept of embedding quantum simulator, a paradigm allowing efficient computation of dynamical quantities requiring full quantum tomography in a standard quantum simulator (one-to-one quantum simulator). The concept consists in the suitable encoding of a simulated quantum dynamics in the enlarged Hilbert space of an embedding quantum simulator. In this manner, non-trivial quantities are mapped onto physical observables, overcoming the necessity of full tomography, and reducing drastically the experimental requirements. As examples, we discuss how to evaluate entanglement monotones and time correlation functions, each in a suitable embedding quantum simulator. Finally, we expect that the proposed embedding framework paves the way for a general theory of enhanced one-to-one quantum simulators. This work is supported by Spanish MINECO FIS2012-36673-C03-02; UPV/EHU UFI 11/55; UPV/EHU PhD fellowship; Basque Government IT472-10; SOLID, CCQED, PROMISCE, SCALEQIT EU projects; and Marco Polo PUCP grant.

  5. Interactive reservoir simulation

    SciTech Connect

    Regtien, J.M.M. Por, G.J.A.; Stiphout, M.T. van; Vlugt, F.F. van der

    1995-12-31

    Shell`s new Modular Reservoir Simulator (MoReS) has been equipped with a comprehensive and versatile user interface called FrontEnd. Apart from providing a user-friendly environment for interactive reservoir simulation, FrontEnd serves a software platform for other dynamic simulation and reservoir-engineering applications. It offers to all supported applications a common user interface, enables the re-use of code and reduces overall maintenance and support costs associated with the embedded applications. Because of its features, FrontEnd facilitates the transfer of research results in the form of operational software to end users. When coupled with MoReS, FrontEnd can be used for pre- and post-processing and interactive simulation. The pre-processing options allow data to be inputted by means of various OSF/Motif widgets containing a spreadsheet, text editors, dialogues and graphical input. The display of the input data as well as the post-processing of all simulation results is made possible by a variety of user-defined plot of tabular (e.g. timestep summary) and array (simulation grid) data. During a simulation user-defined plots can be displayed and edited, allowing a close inspection of the results as they are being calculated. FrontEnd has been equipped with a powerful input command language, which gives the batch user as much flexibility and control over the input as the interactive user.

  6. Simulation of Plasma Etching

    NASA Astrophysics Data System (ADS)

    Moroz, Paul; Moroz, Daniel

    2016-09-01

    Plasma is an indispensable tool in materials processing. It provides chemically and physically active species and directional flows of energetic species enabling deep etching with good straight profiles required by the industry. At present time, the only feasible methods of simulating the resulting feature profiles are those which fall within the scope of feature-scale (FS) simulation methods, utilizing engineering-type of reactions of incoming species with solid materials. At the same time, the molecule dynamics (MD) methods are emerging as an important alternative approach to simulating extremely small features with sizes below of a few nanometers. In our presentation, we discuss both FS methods implemented into the FPS3D code and MD methods implemented into the MDSS code. We also discuss the ways of extracting information about the reactions and interactions used in FS codes from the MD simulations utilizing the approach of interatomic potentials. For this presentation, we selected two types of simulation cases for etching. The first type considers simulation of mostly etching and implantation, such as during Si etching by chlorine-argon plasma. The second type considers ALE (atomic layer etch) when etching is done by a cyclic process of surface passivation/activation with the following process of etching/removal of a single atomic layer per cycle or per a few cycles, allowing ultimate processing accuracy. The simulations are carried out with both FS and MD codes to provide the data for relation and comparison between those two very different approaches.

  7. SOFIA tracking image simulation

    NASA Astrophysics Data System (ADS)

    Taylor, Charles R.; Gross, Michael A. K.

    2016-09-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) tracking camera simulator is a component of the Telescope Assembly Simulator (TASim). TASim is a software simulation of the telescope optics, mounting, and control software. Currently in its fifth major version, TASim is relied upon for telescope operator training, mission planning and rehearsal, and mission control and science instrument software development and testing. TASim has recently been extended for hardware-in-the-loop operation in support of telescope and camera hardware development and control and tracking software improvements. All three SOFIA optical tracking cameras are simulated, including the Focal Plane Imager (FPI), which has recently been upgraded to the status of a science instrument that can be used on its own or in parallel with one of the seven infrared science instruments. The simulation includes tracking camera image simulation of starfields based on the UCAC4 catalog at real-time rates of 4-20 frames per second. For its role in training and planning, it is important for the tracker image simulation to provide images with a realistic appearance and response to changes in operating parameters. For its role in tracker software improvements, it is vital to have realistic signal and noise levels and precise star positions. The design of the software simulation for precise subpixel starfield rendering (including radial distortion), realistic point-spread function as a function of focus, tilt, and collimation, and streaking due to telescope motion will be described. The calibration of the simulation for light sensitivity, dark and bias signal, and noise will also be presented

  8. Global Feedback Simulator

    SciTech Connect

    Carlos Serrano, Lawrence Doolittle

    2015-10-29

    GFS is a simulation engine that is used for the characterization of Accelerator performance parameters based on the machine layout, configuration and noise sources. It combines extensively tested Feedback models with a longitudinal phase space tracking simulator along with the interaction between the two via beam-based feedback using a computationally efficient simulation engine. The models include beam instrumentation, considerations on loop delays for in both the R and beam-based feedback loops, as well as the ability to inject noise (both correlated and uncorrelated) at different points of the machine including a full characterization of the electron gun performance parameters.

  9. Plasma Theory and Simulation.

    DTIC Science & Technology

    1982-06-30

    potential (smooth curve ) and the potential from the field solve (rough curve ).There are 2048 simulation cells and 100,000 particle$. The magnetic field... curve is that obtained from the simulation test particles. An average over :was made of 100 grid cells about the given position. -6- r’ B. Alfvin Ion...AND SIMULATION - i - I January I to Jun~e 30, 1982 .. -.. :.- DOE. Contract DE,--TO3-76ET53064 -I,’,_ ONR Contract NOO014-).C-0578 =" "{DTIC ~ JUL 7

  10. Team training/simulation.

    PubMed

    Clark, Erin A S; Fisher, Janet; Arafeh, Julia; Druzin, Maurice

    2010-03-01

    Obstetrical emergencies require the rapid formation of a team with clear communication, strong leadership, and appropriate decision-making to ensure a positive patient outcome. Obstetric teams can improve their emergency response capability and efficiency through team and simulation training. Postpartum hemorrhage is an ideal model for team and simulation training, as postpartum hemorrhage requires a multidisciplinary team with the capability to produce a protocol-driven, rapid response. This article provides an overview of team and simulation training and focuses on applications within obstetrics, particularly preparation for postpartum hemorrhage.

  11. Vortex breakdown simulation

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.; Leonard, A.; Spalart, P. R.

    1985-01-01

    A vortex breakdown was simulated by the vortex filament method, and detailed figures are presented based on the results. Deformations of the vortex filaments showed clear and large swelling at a particular axial station which implied the presence of a recirculation bubble at that station. The tendency for two breakdowns to occur experimentally was confirmed by the simulation, and the jet flow inside the bubble was well simulated. The particle paths spiralled with expansion, and the streamlines took spiral forms at the breakdown with expansion.

  12. Bioinspired swimming simulations

    NASA Astrophysics Data System (ADS)

    Bergmann, Michel; Iollo, Angelo

    2016-10-01

    We present a method to simulate the flow past bioinspired swimmers starting from pictures of an actual fish. The overall approach requires i) a skeleton graph generation to get a level-set function from pictures; ii) optimal transportation to obtain the velocity on the body surface; iii) flow simulations realized with a Cartesian method based on penalization. This technique can be used to automate modeling swimming motion from data collected by biologists. We illustrate this paradigm by simulating the swimming of a mackerel fish.

  13. Simulation of a microgrid

    NASA Astrophysics Data System (ADS)

    Dulǎu, Lucian Ioan

    2015-12-01

    This paper describes the simulation of a microgrid system with storage technologies. The microgrid comprises 6 distributed generators (DGs), 3 loads and a 150 kW storage unit. The installed capacity of the generators is 1100 kW, while the total load demand is 900 kW. The simulation is performed by using a SCADA software, considering the power generation costs, the loads demand and the system's power losses. The generators access the system in order of their power generation cost. The simulation is performed for the entire day.

  14. Computer-simulated phacoemulsification

    NASA Astrophysics Data System (ADS)

    Laurell, Carl-Gustaf; Nordh, Leif; Skarman, Eva; Andersson, Mats; Nordqvist, Per

    2001-06-01

    Phacoemulsification makes the cataract operation easier for the patient but involves a demanding technique for the surgeon. It is therefore important to increase the quality of surgical training in order to shorten the learning period for the beginner. This should diminish the risks of the patient. We are developing a computer-based simulator for training of phacoemulsification. The simulator is built on a platform that can be used as a basis for several different training simulators. A prototype has been made that has been partly tested by experienced surgeons.

  15. Breathing metabolic simulator.

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G., Jr.; Hendricks, C. M.; Morison, W. B.

    1971-01-01

    Description of a device for simulation of the human breathing and metabolic parameters required for the evaluation of respiratory diagnostic, monitoring, support and resuscitation equipment. The remotely controlled device allows wide variations in breathing rate and depth, breath velocity contour, oxygen uptake and carbon dioxide release to simulate conditions from sleep to hard work, with respiration exchange ratios ranging from hypoventilation to hyperventilation. It also reduces the cost of prolonged testing when simulation chambers with human subjects require three shifts of crews and standby physicians. Several block diagrams of the device and subsystems are given.

  16. XMASS MC simulation

    NASA Astrophysics Data System (ADS)

    Abe, K.

    2016-02-01

    XMASS is a single phase liquid xenon (LXe) detector, designed for a program of physics targets. As a first step in the program, the XMASS-I detector started operation with 832 kg of LXe in the sensitive volume from Sep. 2010. GEANT4 tools are used for the detector simulation to understand the detector response and background. In the simulation detailed structure and processes are required to reproduce background such as detector surface events and Cherenkov events. We present details of the geometry and processes used in the XMASS simulation in this paper.

  17. Solar Sail Spaceflight Simulation

    NASA Technical Reports Server (NTRS)

    Lisano, Michael; Evans, James; Ellis, Jordan; Schimmels, John; Roberts, Timothy; Rios-Reyes, Leonel; Scheeres, Daniel; Bladt, Jeff; Lawrence, Dale; Piggott, Scott

    2007-01-01

    The Solar Sail Spaceflight Simulation Software (S5) toolkit provides solar-sail designers with an integrated environment for designing optimal solar-sail trajectories, and then studying the attitude dynamics/control, navigation, and trajectory control/correction of sails during realistic mission simulations. Unique features include a high-fidelity solar radiation pressure model suitable for arbitrarily-shaped solar sails, a solar-sail trajectory optimizer, capability to develop solar-sail navigation filter simulations, solar-sail attitude control models, and solar-sail high-fidelity force models.

  18. Structural mechanics simulations

    NASA Technical Reports Server (NTRS)

    Biffle, Johnny H.

    1992-01-01

    Sandia National Laboratory has a very broad structural capability. Work has been performed in support of reentry vehicles, nuclear reactor safety, weapons systems and components, nuclear waste transport, strategic petroleum reserve, nuclear waste storage, wind and solar energy, drilling technology, and submarine programs. The analysis environment contains both commercial and internally developed software. Included are mesh generation capabilities, structural simulation codes, and visual codes for examining simulation results. To effectively simulate a wide variety of physical phenomena, a large number of constitutive models have been developed.

  19. Digital camera simulation.

    PubMed

    Farrell, Joyce E; Catrysse, Peter B; Wandell, Brian A

    2012-02-01

    We describe a simulation of the complete image processing pipeline of a digital camera, beginning with a radiometric description of the scene captured by the camera and ending with a radiometric description of the image rendered on a display. We show that there is a good correspondence between measured and simulated sensor performance. Through the use of simulation, we can quantify the effects of individual digital camera components on system performance and image quality. This computational approach can be helpful for both camera design and image quality assessment.

  20. Dynamical Simulation of Probabilities

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1996-01-01

    It has been demonstrated that classical probabilities, and in particular, probabilistic Turing machine, can be simulated by combining chaos and non-Lipschitz dynamics, without utilization of any man-made devices(such as random number generators). Self-orgainizing properties of systems coupling simulated and calculated probabilities and their link to quantum computations are discussed. Special attention was focused upon coupled stochastic processes, defined in terms of conditional probabilities, for which joint probability does not exist. Simulations of quantum probabilities are also discussed.

  1. Distributed Simulation for Space Exploration

    NASA Technical Reports Server (NTRS)

    Crues, Edwin Z.

    2006-01-01

    This viewgraph presentation reviews the use of simulation and modeling in preparation for the planned exploration initiatives. The Exploration Systems Mission Directorate (EMSD) Integrated Modeling and Simulation (IM&S) team strategy encompasses a wide spectrum of simulation and modeling policies and technologies. One prominent technology is distributed simulation. The DIstributed Simulation (DIS),a collaborative simulation project with international participation (US and Japan) is reviewed as an example of distributed simulation development. The Distributed Space Exploration Simulation (DSES) is another example of distributed simulation that is described

  2. Comment on “Equilibrium constants and rate constants for adsorbates: Two-dimensional (2D) ideal gas, 2D ideal lattice gas, and ideal hindered translator models”

    SciTech Connect

    Savara, Aditya

    2016-08-15

    The paper by Campbell et al. was recently brought to my attention. This comment is written to provide greater clarity to the community to prevent misconceptions regarding the entropies being discussed in that work and to clarify the differences between the adsorbate standard states suggested by Campbell and by Savara.

  3. TGF simulation movie

    NASA Video Gallery

    A TGF produces gamma rays (magenta) as well as high-energy electrons (yellow) and positrons (green). This simulation tracks a TGF and its particle beams from their origin altitude of 9.3 miles (15 ...

  4. Gemini Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Gemini Rendezvous Docking Simulator suspended from the roof of the Langley Research Center's aircraft hanger. Francis B. Smith wrote: 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.'

  5. Rocket engine numerical simulation

    NASA Technical Reports Server (NTRS)

    Davidian, Ken

    1993-01-01

    The topics are presented in view graph form and include the following: a definition of the rocket engine numerical simulator (RENS); objectives; justification; approach; potential applications; potential users; RENS work flowchart; RENS prototype; and conclusions.

  6. Rocket engine numerical simulator

    NASA Technical Reports Server (NTRS)

    Davidian, Ken

    1993-01-01

    The topics are presented in viewgraph form and include the following: a rocket engine numerical simulator (RENS) definition; objectives; justification; approach; potential applications; potential users; RENS work flowchart; RENS prototype; and conclusion.

  7. Breathing metabolic simulator

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G.; Hendricks, C. M.; Morison, W. B.

    1972-01-01

    The development of a breathing metabolic simulator (BMS) is reported. This BMS simulates all of the breathing and metabolic parameters required for complete evaluation and test of life support and resuscitation equipment. It is also useful for calibrating and validating mechanical and gaseous pulmonary function test procedures. Breathing rate, breathing depth, breath velocity contour, oxygen uptake, and carbon dioxide release are all variable over wide ranges simulating conditions from sleep to hard work with respiratory exchange ratios covering the range from hypoventilation. In addition, all of these parameters are remotely controllable to facilitate use of the device in hostile or remote environments. The exhaled breath is also maintained at body temperature and a high humidity. The simulation is accurate to the extent of having a variable functional residual capacity independent of other parameters.

  8. Simulation of Gravitational Microlensing

    NASA Video Gallery

    This simulation shows the 22-year journey of a star moving through space and passing directly in front of a more distant background star. All stars drift through space. Occasionally, a star lines u...

  9. Compressible Astrophysics Simulation Code

    SciTech Connect

    Howell, L.; Singer, M.

    2007-07-18

    This is an astrophysics simulation code involving a radiation diffusion module developed at LLNL coupled to compressible hydrodynamics and adaptive mesh infrastructure developed at LBNL. One intended application is to neutrino diffusion in core collapse supernovae.

  10. Television Quiz Show Simulation

    ERIC Educational Resources Information Center

    Hill, Jonnie Lynn

    2007-01-01

    This article explores the simulation of four television quiz shows for students in China studying English as a foreign language (EFL). It discusses the adaptation and implementation of television quiz shows and how the students reacted to them.

  11. Dynamic Power Grid Simulation

    SciTech Connect

    Top, Philip; Woodward, Carol; Smith, Steve; Banks, Lawrence; Kelley, Brian

    2015-09-14

    GridDyn is a part of power grid simulation toolkit. The code is designed using modern object oriented C++ methods utilizing C++11 and recent Boost libraries to ensure compatibility with multiple operating systems and environments.

  12. Chemical Transformation Simulator

    EPA Science Inventory

    The Chemical Transformation Simulator (CTS) is a web-based, high-throughput screening tool that automates the calculation and collection of physicochemical properties for an organic chemical of interest and its predicted products resulting from transformations in environmental sy...

  13. Color Blindness Simulations

    MedlinePlus

    ... Coordinator Color blindness Simulations Normal Color Vision Deuteranopia Color blindness marked by confusion of purplish red and green Tritanopia A dichromatism in which the spectrum is seen in tones of red and green. ...

  14. Image simulation using LOCUS

    SciTech Connect

    Strachan, J.D.; Roberts, J.A.

    1989-09-01

    The LOCUS data base program has been used to simulate images and to solve simple equations. This has been accomplished by making each record (which normally would represent a data entry)represent sequenced or random number pairs.

  15. Electromechanical simulations of dislocations

    NASA Astrophysics Data System (ADS)

    Skiba, Oxana; Gracie, Robert; Potapenko, Stanislav

    2013-04-01

    Improving the reliability of micro-electronic devices depends in part on developing a more in-depth understanding of dislocations because dislocations are barriers to charge carriers. To this end, the quasi-static simulation of discrete dislocations dynamics in materials under mechanical and electrical loads is presented. The simulations are based on the extended finite element method, where dislocations are modelled as internal discontinuities. The strong and weak forms of the boundary value problem for the coupled system are presented. The computation of the Peach-Koehler force using the J-integral is discussed. Examples to illustrate the accuracy of the simulations are presented. The motion of the network of the dislocations under different electrical and mechanical loads is simulated. It was shown that even in weak piezoelectric materials the effect of the electric field on plastic behaviour is significant.

  16. Artillery Engagement Simulation

    DTIC Science & Technology

    1980-05-01

    normally are conveyed to appropriate military agencies by briefing or Disposition Form. kS iv FOREWORD Current Army Training and Evaluation Programs (ARTEP...ENGAGEMENT SIMULATION BRIEF Requirement: To develop and evaluate a method for incorporating the field artillery battery into engagement simulation (ES...assisted by two E-3 drivers. Both were proficient in their MOS. To check the accuracy of the firemarkers, a flash base of three observation posts and a

  17. Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Multiple exposure of Rendezvous Docking Simulator. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. The controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.

  18. Geothermal reservoir simulation

    NASA Technical Reports Server (NTRS)

    Mercer, J. W., Jr.; Faust, C.; Pinder, G. F.

    1974-01-01

    The prediction of long-term geothermal reservoir performance and the environmental impact of exploiting this resource are two important problems associated with the utilization of geothermal energy for power production. Our research effort addresses these problems through numerical simulation. Computer codes based on the solution of partial-differential equations using finite-element techniques are being prepared to simulate multiphase energy transport, energy transport in fractured porous reservoirs, well bore phenomena, and subsidence.

  19. Xyce parallel electronic simulator.

    SciTech Connect

    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.

  20. Simulator manufacturers' requirements

    NASA Technical Reports Server (NTRS)

    Reilly, David R.

    1987-01-01

    Simulator manufacturers must continue to provide the customers the latest wind shear models available for pilot training. The release of the JAWS data package enabled the provision of a much more realistic wind shear package to the customer rather than just the standard six SRI wind shear profiles currently in use. In this brief presentation, the steps taken in implementing the JAWS data into the FAA 727 simulator are highlighted.

  1. Optimization Of Simulated Trajectories

    NASA Technical Reports Server (NTRS)

    Brauer, Garry L.; Olson, David W.; Stevenson, Robert

    1989-01-01

    Program To Optimize Simulated Trajectories (POST) provides ability to target and optimize trajectories of point-mass powered or unpowered vehicle operating at or near rotating planet. Used successfully to solve wide variety of problems in mechanics of atmospheric flight and transfer between orbits. Generality of program demonstrated by its capability to simulate up to 900 distinct trajectory phases, including generalized models of planets and vehicles. VAX version written in FORTRAN 77 and CDC version in FORTRAN V.

  2. Water hammer simulator

    SciTech Connect

    Sinha, S.K.; Madia, J.; Dixon, S.

    1995-11-01

    The Consolidated Edison Company of New York, Inc. (Con Edison) has constructed a first-of-a-kind water hammer events simulator for use at its training center. The Learning Center, Con Edison`s central training facility, intends to use the simulator as an educational tool to demonstrate the various mechanisms of the water hammer phenomenon to power plant designers, engineers and operators. The water hammer phenomenon has been studied extensively for the past 15 years for the nuclear industry. However, the acknowledge of the various water hammer mechanisms and the measures to prevent or mitigate water hammer have not been widely disseminated among the operators of fossil-fueled power plants. Con Edison personnel who operate the various generation stations and the New York City steam distribution systems are expected to benefit from the new simulator. Knowledge gained from interacting with the simulator will be very important in helping the Con Edison prevent, mitigate, or accommodate water hammer at its facilities. The water hammer simulator was fabricated in Con Edison`s central machine shop. Details of the design and construction of the simulator were finalized in consultation with Creare, Inc., an engineering research firm, located in Hanover, New Hampshire. The simulator seeks to recreate the essential features of water hammer in steam mines following the buildup of cold (subcooled) water by condensation and steam-water interaction. This paper describes the fabrication, design, testing, and operation of the Con Edison water hammer simulator. A discussion of how Con Edison plans to use the facility at The Learning Center is included.

  3. Simulators and Enhanced Training

    DTIC Science & Technology

    1992-04-01

    realistic for the particular tasks to be trained. Secondly, the relation of cost to realism is neither linear nor the same for different tasks. Figure...time spent training on a simulation. An algebraic I representation of this ratio is (Awo - Aw’)/S, where Awo is the training time in the actual... Friedberg , Schweinfurt, and Fulda. The Fort Knox site is currently the largest SIMNET facility with simulators for 44 M1 Abrams tanks, 28 M2/3 Bradley

  4. Theory Modeling and Simulation

    SciTech Connect

    Shlachter, Jack

    2012-08-23

    Los Alamos has a long history in theory, modeling and simulation. We focus on multidisciplinary teams that tackle complex problems. Theory, modeling and simulation are tools to solve problems just like an NMR spectrometer, a gas chromatograph or an electron microscope. Problems should be used to define the theoretical tools needed and not the other way around. Best results occur when theory and experiments are working together in a team.

  5. Solenoid-Simulation Circuit

    NASA Technical Reports Server (NTRS)

    Simon, R. A.

    1986-01-01

    Electrical properties of solenoids imitated for tests of control circuits. Simulation circuit imitates voltage and current responses of two engine-controlling solenoids. Used in tests of programs of digital engine-control circuits, also provides electronic interface with circuits imitating electrical properties of pressure sensors and linear variable-differential transformers. Produces voltages, currents, delays, and discrete turnon and turnoff signals representing operation of solenoid in engine-control relay. Many such circuits used simulating overall engine circuitry.

  6. Intelligently interactive combat simulation

    NASA Astrophysics Data System (ADS)

    Fogel, Lawrence J.; Porto, Vincent W.; Alexander, Steven M.

    2001-09-01

    To be fully effective, combat simulation must include an intelligently interactive enemy... one that can be calibrated. But human operated combat simulations are uncalibratable, for we learn during the engagement, there's no average enemy, and we cannot replicate their culture/personality. Rule-based combat simulations (expert systems) are not interactive. They do not take advantage of unexpected mistakes, learn, innovate, and reflect the changing mission/situation. And it is presumed that the enemy does not have a copy of the rules, that the available experts are good enough, that they know why they did what they did, that their combat experience provides a sufficient sample and that we know how to combine the rules offered by differing experts. Indeed, expert systems become increasingly complex, costly to develop, and brittle. They have face validity but may be misleading. In contrast, intelligently interactive combat simulation is purpose- driven. Each player is given a well-defined mission, reference to the available weapons/platforms, their dynamics, and the sensed environment. Optimal tactics are discovered online and in real-time by simulating phenotypic evolution in fast time. The initial behaviors are generated randomly or include hints. The process then learns without instruction. The Valuated State Space Approach provides a convenient way to represent any purpose/mission. Evolutionary programming searches the domain of possible tactics in a highly efficient manner. Coupled together, these provide a basis for cruise missile mission planning, and for driving tank warfare simulation. This approach is now being explored to benefit Air Force simulations by a shell that can enhance the original simulation.

  7. Accelerator simulation using computers

    SciTech Connect

    Lee, M.; Zambre, Y.; Corbett, W.

    1992-01-01

    Every accelerator or storage ring system consists of a charged particle beam propagating through a beam line. Although a number of computer programs exits that simulate the propagation of a beam in a given beam line, only a few provide the capabilities for designing, commissioning and operating the beam line. This paper shows how a multi-track'' simulation and analysis code can be used for these applications.

  8. Accelerator simulation using computers

    SciTech Connect

    Lee, M.; Zambre, Y.; Corbett, W.

    1992-01-01

    Every accelerator or storage ring system consists of a charged particle beam propagating through a beam line. Although a number of computer programs exits that simulate the propagation of a beam in a given beam line, only a few provide the capabilities for designing, commissioning and operating the beam line. This paper shows how a ``multi-track`` simulation and analysis code can be used for these applications.

  9. TANGO ARRAY II: Simulations

    NASA Astrophysics Data System (ADS)

    Bauleo, P.; Bonifazi, C.; Filevich, A.

    The angular and energy resolution of the TANGO Array has been obtained using Monte Carlo simulations. The AIRES code, with the SYBILL hadronic collision package, was used to simulate Extended Air Showers produced by primary cosmic rays (protons and iron nuclei), with energies ranging from 1014 eV to 1018 eV. These data were fed into a realistic code which simulates the response of the detector stations (water ˇCerenkov detectors), including the electronics, pick up noise, and the signal attenuation in the connecting cabling. The trigger stage is taken into account in order to produce estimates of the trigger efficiency of the array and to check the accuracy of the reconstruction codes. This paper describes the simulations performed to obtain the expected behavior of the array, and presents the simulated data. These simulations indicate that the accuracy of the cosmic ray primary energy determination is expected to be ˜ 60 % and the precision in the measurement of the direction of arrival can be estimated as ˜ 4 degrees.

  10. Mission Simulation Toolkit

    NASA Technical Reports Server (NTRS)

    Pisaich, Gregory; Flueckiger, Lorenzo; Neukom, Christian; Wagner, Mike; Buchanan, Eric; Plice, Laura

    2007-01-01

    The Mission Simulation Toolkit (MST) is a flexible software system for autonomy research. It was developed as part of the Mission Simulation Facility (MSF) project that was started in 2001 to facilitate the development of autonomous planetary robotic missions. Autonomy is a key enabling factor for robotic exploration. There has been a large gap between autonomy software (at the research level), and software that is ready for insertion into near-term space missions. The MST bridges this gap by providing a simulation framework and a suite of tools for supporting research and maturation of autonomy. MST uses a distributed framework based on the High Level Architecture (HLA) standard. A key feature of the MST framework is the ability to plug in new models to replace existing ones with the same services. This enables significant simulation flexibility, particularly the mixing and control of fidelity level. In addition, the MST provides automatic code generation from robot interfaces defined with the Unified Modeling Language (UML), methods for maintaining synchronization across distributed simulation systems, XML-based robot description, and an environment server. Finally, the MSF supports a number of third-party products including dynamic models and terrain databases. Although the communication objects and some of the simulation components that are provided with this toolkit are specifically designed for terrestrial surface rovers, the MST can be applied to any other domain, such as aerial, aquatic, or space.

  11. Simulating the local Universe

    NASA Astrophysics Data System (ADS)

    Sorce, J. G.

    2016-12-01

    In the local Universe, cosmic structures can be observed down to very small scales, scales on which the standard cosmological model might fail. Such detailed observations have to be compared with simulations in order to verify the predictions of different cosmological models. However, the cosmic variance can obscure the tests. More precisely, comparisons on a one-to-one basis are feasible only with simulations that look like the local Universe. Constrained by observed positions and peculiar velocities of galaxies, the simulations presented here reproduce locally the three-dimensional distribution of matter. Within a sphere of radius 100 hMpc, the observed nearby Large and Small Scale Structure is simulated with an accuracy of a few megaparsecs. These simulations include our nearest cluster neighbor, Virgo, allowing a detailed study of its formation history. It follows that the Virgo cluster has had a quiet merging history within the last seven gigayears. In the near future, zoom-in hydrodynamical simulations of the later will permit deeper comparisons with observations.

  12. Simulation of turbulent wall pressure

    NASA Technical Reports Server (NTRS)

    Ash, R. L.

    1976-01-01

    A computer program has been developed to simulate the transient wall pressure field produced by a low speed fully turbulent boundary layer. The theoretical basis for the simulation has been discussed and preliminary results from a pressure simulation are presented.

  13. Converting DYNAMO simulations to Powersim Studio simulations

    SciTech Connect

    Walker, La Tonya Nicole; Malczynski, Leonard A.

    2014-02-01

    DYNAMO is a computer program for building and running 'continuous' simulation models. It was developed by the Industrial Dynamics Group at the Massachusetts Institute of Technology for simulating dynamic feedback models of business, economic, and social systems. The history of the system dynamics method since 1957 includes many classic models built in DYANMO. It was not until the late 1980s that software was built to take advantage of the rise of personal computers and graphical user interfaces that DYNAMO was supplanted. There is much learning and insight to be gained from examining the DYANMO models and their accompanying research papers. We believe that it is a worthwhile exercise to convert DYNAMO models to more recent software packages. We have made an attempt to make it easier to turn these models into a more current system dynamics software language, Powersim © Studio produced by Powersim AS2 of Bergen, Norway. This guide shows how to convert DYNAMO syntax into Studio syntax.

  14. The cathode plasma simulation

    NASA Astrophysics Data System (ADS)

    Suksila, Thada

    Since its invention at the University of Stuttgart, Germany in the mid-1960, scientists have been trying to understand and explain the mechanism of the plasma interaction inside the magnetoplasmadynamics (MPD) thruster. Because this thruster creates a larger level of efficiency than combustion thrusters, this MPD thruster is the primary cadidate thruster for a long duration (planetary) spacecraft. However, the complexity of this thruster make it difficult to fully understand the plasma interaction in an MPD thruster while operating the device. That is, there is a great deal of physics involved: the fluid dynamics, the electromagnetics, the plasma dynamics, and the thermodynamics. All of these physics must be included when an MPD thruster operates. In recent years, a computer simulation helped scientists to simulate the experiments by programing the physics theories and comparing the simulation results with the experimental data. Many MPD thruster simulations have been conducted: E. Niewood et al.[5], C. K. J. Hulston et al.[6], K. D. Goodfellow[3], J Rossignol et al.[7]. All of these MPD computer simulations helped the scientists to see how quickly the system responds to the new design parameters. For this work, a 1D MPD thruster simulation was developed to find the voltage drop between the cathode and the plasma regions. Also, the properties such as thermal conductivity, electrical conductivity and heat capacity are temperature and pressure dependent. These two conductivity and heat capacity are usually definded as constant values in many other models. However, this 1D and 2D cylindrical symmetry MPD thruster simulations include both temperature and pressure effects to the electrical, thermal conductivities and heat capacity values interpolated from W. F. Ahtye [4]. Eventhough, the pressure effect is also significant; however, in this study the pressure at 66 Pa was set as a baseline. The 1D MPD thruster simulation includes the sheath region, which is the

  15. Reduced Gravity Walking Simulator

    NASA Technical Reports Server (NTRS)

    1963-01-01

    A test subject being suited up for studies on the Reduced Gravity Walking Simulator located in the hanger at Langley Research Center. The initial version of this simulator was located inside the hanger. Later a larger version would be located at the Lunar Landing Facility. The purpose of this simulator was to study the subject while walking, jumping or running. Researchers conducted studies of various factors such as fatigue limit, energy expenditure, and speed of locomotion. Francis B. Smith wrote in his paper 'Simulators For Manned Space Research,' 'I would like to conclude this talk with a discussion of a device for simulating lunar gravity which is very effective and yet which is so simple that its cost is in the order of a few thousand dollars at most, rather than hundreds of thousands. With a little ingenuity, one could almost build this type simulator in his backyard for children to play on. The principle is ...if a test subject is suspended in a sling so that his body axis makes an angle of 9 1/2 degrees with the horizontal and if he then 'stands' on a platform perpendicular to his body axis, the component of the earth's gravity forcing him toward the platform is one times the sine of 9 1/2 degrees or approximately 1/6 of the earth's normal gravity field. That is, a 180 pound astronaut 'standing' on the platform would exert a force of only 30 pounds - the same as if he were standing upright on the lunar surface.' Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, NASA SP-4308; Francis B. Smith, 'Simulators For Manned Space Research,' Paper for 1966 IEEE International Convention, New York, NY, March 21-25, 1966.

  16. EMU Suit Performance Simulation

    NASA Technical Reports Server (NTRS)

    Cowley, Matthew S.; Benson, Elizabeth; Harvill, Lauren; Rajulu, Sudhakar

    2014-01-01

    Introduction: Designing a planetary suit is very complex and often requires difficult trade-offs between performance, cost, mass, and system complexity. To verify that new suit designs meet requirements, full prototypes must be built and tested with human subjects. However, numerous design iterations will occur before the hardware meets those requirements. Traditional draw-prototype-test paradigms for research and development are prohibitively expensive with today's shrinking Government budgets. Personnel at NASA are developing modern simulation techniques that focus on a human-centric design paradigm. These new techniques make use of virtual prototype simulations and fully adjustable physical prototypes of suit hardware. This is extremely advantageous and enables comprehensive design down-selections to be made early in the design process. Objectives: The primary objective was to test modern simulation techniques for evaluating the human performance component of two EMU suit concepts, pivoted and planar style hard upper torso (HUT). Methods: This project simulated variations in EVA suit shoulder joint design and subject anthropometry and then measured the differences in shoulder mobility caused by the modifications. These estimations were compared to human-in-the-loop test data gathered during past suited testing using four subjects (two large males, two small females). Results: Results demonstrated that EVA suit modeling and simulation are feasible design tools for evaluating and optimizing suit design based on simulated performance. The suit simulation model was found to be advantageous in its ability to visually represent complex motions and volumetric reach zones in three dimensions, giving designers a faster and deeper comprehension of suit component performance vs. human performance. Suit models were able to discern differing movement capabilities between EMU HUT configurations, generic suit fit concerns, and specific suit fit concerns for crewmembers based

  17. Videodisc Simulation: Tomorrow's Technology Today.

    ERIC Educational Resources Information Center

    Young, Jon I.

    1984-01-01

    Describes the positive features, significant benefits, and learner interaction modes of videodisc simulation technology and discusses the development of a program structure which utilizes videodisc simulation. (MBR)

  18. Range Process Simulation Tool

    NASA Technical Reports Server (NTRS)

    Phillips, Dave; Haas, William; Barth, Tim; Benjamin, Perakath; Graul, Michael; Bagatourova, Olga

    2005-01-01

    Range Process Simulation Tool (RPST) is a computer program that assists managers in rapidly predicting and quantitatively assessing the operational effects of proposed technological additions to, and/or upgrades of, complex facilities and engineering systems such as the Eastern Test Range. Originally designed for application to space transportation systems, RPST is also suitable for assessing effects of proposed changes in industrial facilities and large organizations. RPST follows a model-based approach that includes finite-capacity schedule analysis and discrete-event process simulation. A component-based, scalable, open architecture makes RPST easily and rapidly tailorable for diverse applications. Specific RPST functions include: (1) definition of analysis objectives and performance metrics; (2) selection of process templates from a processtemplate library; (3) configuration of process models for detailed simulation and schedule analysis; (4) design of operations- analysis experiments; (5) schedule and simulation-based process analysis; and (6) optimization of performance by use of genetic algorithms and simulated annealing. The main benefits afforded by RPST are provision of information that can be used to reduce costs of operation and maintenance, and the capability for affordable, accurate, and reliable prediction and exploration of the consequences of many alternative proposed decisions.

  19. Training using medical simulation.

    PubMed

    Grant, David J; Marriage, Stephen C

    2012-03-01

    As the time available for medical education is shortened by reductions in training hours and the demands of modern healthcare delivery, educators are increasingly looking towards simulation as a means of providing safe and reproducible situations for clinical skills teaching, decision-making and team training. The tools available for simulation-based training have developed rapidly over the past 15 years. There is an increasing range of manikins and part-task trainers - devices that permit selected elements of a skill or task to be practised independently of a whole-body manikin. Those interested in simulation have also focused significantly on adult learning theory to ensure that the training offered through simulation is appropriate, effective and complementary to other educational approaches. By mapping simulated scenarios to the Royal College of Paediatrics and Child Health Curriculum for General Paediatric Training at Level 1, the authors have developed two complementary courses aimed at preparing the general paediatric trainee for progression to the middle grade role. It is hoped that such approaches will become integral to paediatric training in the future.

  20. Multilevel turbulence simulations

    SciTech Connect

    Tziperman, E.

    1994-12-31

    The authors propose a novel method for the simulation of turbulent flows, that is motivated by and based on the Multigrid (MG) formalism. The method, called Multilevel Turbulence Simulations (MTS), is potentially more efficient and more accurate than LES. In many physical problems one is interested in the effects of the small scales on the larger ones, or in a typical realization of the flow, and not in the detailed time history of each small scale feature. MTS takes advantage of the fact that the detailed simulation of small scales is not needed at all times, in order to make the calculation significantly more efficient, while accurately accounting for the effects of the small scales on the larger scale of interest. In MTS, models of several resolutions are used to represent the turbulent flow. The model equations in each coarse level incorporate a closure term roughly corresponding to the tau correction in the MG formalism that accounts for the effects of the unresolvable scales on that grid. The finer resolution grids are used only a small portion of the simulation time in order to evaluate the closure terms for the coarser grids, while the coarse resolution grids are then used to accurately and efficiently calculate the evolution of the larger scales. The methods efficiency relative to direct simulations is of the order of the ratio of required integration time to the smallest eddies turnover time, potentially resulting in orders of magnitude improvement for a large class of turbulence problems.

  1. QTLMAS 2009: simulated dataset

    PubMed Central

    2010-01-01

    Background The simulation of the data for the QTLMAS 2009 Workshop is described. Objective was to simulate observations from a growth curve which was influenced by a number of QTL. Results The data consisted of markers, phenotypes and pedigree. Genotypes of 453 markers, distributed over 5 chromosomes of 1 Morgan each, were simulated for 2,025 individuals. From those, 25 individuals were parents of the other 2,000 individuals. The 25 parents were genetically related. Phenotypes were simulated according to a logistic growth curve and were made available for 1,000 of the 2,000 offspring individuals. The logistic growth curve was specified by three parameters. Each parameter was influenced by six Quantitative Trait Loci (QTL), positioned at the five chromosomes. For each parameter, one QTL had a large effect and five QTL had small effects. Variance of large QTL was five times the variance of small QTL. Simulated data was made available at http://www.qtlmas2009.wur.nl/UK/Dataset/. PMID:20380757

  2. Simulations of Granular Media

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Müller, M.

    For the last ten years there has been an enormous progress in the simulation of granular media like sand or powders. These simulations consist in simulating trajectories of each particle individually. Essentially one has to solve the Newton's equations including the effects of Coulomb friction and the physics occuring at a collision. But the details of the trajectories are not important for the collective behaviour. Therefore simplifications are introduced on the smallest scales. I will introduce various methods like molecular dynamics that are used to simulate large amounts of particles (over 109). Some of these medhods are based on the exploitation of parallelisation and metacomputing. Other approaches are more stochastic (DSMC Direct Simulation Monte Carlo) which simplify the calculation of collisions, positions and collision times. Very successful has been also the use of cellular automata which have been able to predict details such as the logarithmic tale of sand heaps. I will also discuss numerical techniques used for the surrounding fluid. This can be water in the case of sedimentation or air when one studies the formation of dunes in the desert. The calculation of velocity and pressure field of the fluid are done using multigrid techniques on parallel computers. We will compare the performance of the various techniques and show some benchmarks on the dependence on the size of the system, the density of particles and the number of processors used.

  3. Computer Modeling and Simulation

    SciTech Connect

    Pronskikh, V. S.

    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

  4. The Simulated Law Firm and Other Contemporary Law Simulations

    ERIC Educational Resources Information Center

    Hollander, Patricia A.

    1978-01-01

    Various modes of simulations currently used in law schools are reviewed, including the Simulated Law Firm (SLF) at SUNY Buffalo and various computer-aided teaching programs. Simulation and computer use in the legal profession is reported, followed by a historical description of simulations in teaching and research. Its effectiveness as a teaching…

  5. Simulator verification techniques study. Integrated simulator self test system concepts

    NASA Technical Reports Server (NTRS)

    Montoya, G.; Wenglinski, T. H.

    1974-01-01

    Software and hardware requirements for implementing hardware self tests are presented in support of the development of training and procedures development simulators for the space shuttle program. Self test techniques for simulation hardware and the validation of simulation performance are stipulated. The requirements of an integrated simulator self system are analyzed. Readiness tests, fault isolation tests, and incipient fault detection tests are covered.

  6. Flight code validation simulator

    SciTech Connect

    Sims, B.A.

    1995-08-01

    An End-To-End Simulation capability for software development and validation of missile flight software on the actual embedded computer has been developed utilizing a 486 PC, i860 DSP coprocessor, embedded flight computer and custom dual port memory interface hardware. This system allows real-time interrupt driven embedded flight software development and checkout. The flight software runs in a Sandia Digital Airborne Computer (SANDAC) and reads and writes actual hardware sensor locations in which IMU (Inertial Measurements Unit) data resides. The simulator provides six degree of freedom real-time dynamic simulation, accurate real-time discrete sensor data and acts on commands and discretes from the flight computer. This system was utilized in the development and validation of the successful premier flight of the Digital Miniature Attitude Reference System (DMARS) in January 1995 at the White Sands Missile Range on a two stage attitude controlled sounding rocket.

  7. Robot graphic simulation testbed

    NASA Technical Reports Server (NTRS)

    Cook, George E.; Sztipanovits, Janos; Biegl, Csaba; Karsai, Gabor; Springfield, James F.

    1991-01-01

    The objective of this research was twofold. First, the basic capabilities of ROBOSIM (graphical simulation system) were improved and extended by taking advantage of advanced graphic workstation technology and artificial intelligence programming techniques. Second, the scope of the graphic simulation testbed was extended to include general problems of Space Station automation. Hardware support for 3-D graphics and high processing performance make high resolution solid modeling, collision detection, and simulation of structural dynamics computationally feasible. The Space Station is a complex system with many interacting subsystems. Design and testing of automation concepts demand modeling of the affected processes, their interactions, and that of the proposed control systems. The automation testbed was designed to facilitate studies in Space Station automation concepts.

  8. [Simulation of mental illness].

    PubMed

    Mastronardi, Vincenzo; Del Casale, Antonio

    2012-01-01

    The DSM-IV-TR defines the simulation an "intentional production of physical or psychological symptoms false or grossly exaggerated, motivated by external incentives". The first point to consider is that it has a near zero prevalence in the general population, occurring almost exclusively in people imprisoned, treated in Forensic Psychiatric Hospital, in individuals subjected to trial, or in personalities seen as deviated from a criminological point of view. Both the criteria to set diagnoses of simulation, previously examined by Foreal and Kaufman since 1943, and the relative suspicion indicators, not separated by 'reasons of simulated behavior, are taken into account. The work also addresses several other meanings of self injurious actions appointed by Bachler, as well as the associationist/mechanistic theories of the classical dynamic model and the differential diagnosis with other conditions of Psychiatric Interest and concludes with the topic of "Premeditation".

  9. Collisionless galaxy simulations

    NASA Technical Reports Server (NTRS)

    Hohl, F.; Zang, T. A.; Miller, J. B.

    1979-01-01

    Three-dimensional fully self-consistent computer models were used to determine the evolution of galaxies consisting of 100 000 simulation stars. Comparison of two-dimensional simulations with three-dimensional simulations showed only a very slight stabilizing effect due to the additional degree of freedom. The addition of a fully self-consistent, nonrotating, exponential core/halo component resulted in considerable stabilization. A second series of computer experiments was performed to determine the collapse and relaxation of initially spherical, uniform density and uniform velocity dispersion stellar systems. The evolution of the system was followed for various amounts of angular momentum in solid body rotation. For initally low values of the angular momentum satisfying the Ostriker-Peebles stability criterion, the systems quickly relax to an axisymmetric shape and resemble elliptical galaxies in appearance. For larger values of the initial angular momentum bars develop and the systems undergo a much more drastic evolution.

  10. FASTBUS simulation tools

    SciTech Connect

    Dean, T.D. ); Haney, M.J. )

    1992-08-01

    In this paper a generalized model of a FASTBUS master is presented. The model is used with simulation tools to aid in the specification, design, and production of FASTBUS slave modules. The model provides a mechanism to interact with the electrical schematics and software models to predict performance. The model is written in the IEEE std 1076-1987 hardware description language VHDL. A model of the ATC logic is also presented. VHDL was chosen to provide portability to various platforms and simulation tools. The models, in conjunction with most commercially available simulators, will perform all of the transactions specified in IEEE std 960-1989. The models may be used to study the behavior of electrical schematics and other software models and detect violations of the FASTBUS protocol. For example, a hardware design of a slave module could be studied, protocol violations detected and corrected before committing money to prototype development.

  11. A generic multibody simulation

    NASA Technical Reports Server (NTRS)

    Hopping, K. A.; Kohn, W.

    1986-01-01

    Described is a dynamic simulation package which can be configured for orbital test scenarios involving multiple bodies. The rotational and translational state integration methods are selectable for each individual body and may be changed during a run if necessary. Characteristics of the bodies are determined by assigning components consisting of mass properties, forces, and moments, which are the outputs of user-defined environmental models. Generic model implementation is facilitated by a transformation processor which performs coordinate frame inversions. Transformations are defined in the initialization file as part of the simulation configuration. The simulation package includes an initialization processor, which consists of a command line preprocessor, a general purpose grammar, and a syntax scanner. These permit specifications of the bodies, their interrelationships, and their initial states in a format that is not dependent on a particular test scenario.

  12. Constructive Engineering of Simulations

    NASA Technical Reports Server (NTRS)

    Snyder, Daniel R.; Barsness, Brendan

    2011-01-01

    Joint experimentation that investigates sensor optimization, re-tasking and management has far reaching implications for Department of Defense, Interagency and multinational partners. An adaption of traditional human in the loop (HITL) Modeling and Simulation (M&S) was one approach used to generate the findings necessary to derive and support these implications. Here an entity-based simulation was re-engineered to run on USJFCOM's High Performance Computer (HPC). The HPC was used to support the vast number of constructive runs necessary to produce statistically significant data in a timely manner. Then from the resulting sensitivity analysis, event designers blended the necessary visualization and decision making components into a synthetic environment for the HITL simulations trials. These trials focused on areas where human decision making had the greatest impact on the sensor investigations. Thus, this paper discusses how re-engineering existing M&S for constructive applications can positively influence the design of an associated HITL experiment.

  13. Simulation of Mission Phases

    NASA Technical Reports Server (NTRS)

    Carlstrom, Nicholas Mercury

    2016-01-01

    This position with the Simulation and Graphics Branch (ER7) at Johnson Space Center (JSC) provided an introduction to vehicle hardware, mission planning, and simulation design. ER7 supports engineering analysis and flight crew training by providing high-fidelity, real-time graphical simulations in the Systems Engineering Simulator (SES) lab. The primary project assigned by NASA mentor and SES lab manager, Meghan Daley, was to develop a graphical simulation of the rendezvous, proximity operations, and docking (RPOD) phases of flight. The simulation is to include a generic crew/cargo transportation vehicle and a target object in low-Earth orbit (LEO). Various capsule, winged, and lifting body vehicles as well as historical RPOD methods were evaluated during the project analysis phase. JSC core mission to support the International Space Station (ISS), Commercial Crew Program (CCP), and Human Space Flight (HSF) influenced the project specifications. The simulation is characterized as a 30 meter +V Bar and/or -R Bar approach to the target object's docking station. The ISS was selected as the target object and the international Low Impact Docking System (iLIDS) was selected as the docking mechanism. The location of the target object's docking station corresponds with the RPOD methods identified. The simulation design focuses on Guidance, Navigation, and Control (GNC) system architecture models with station keeping and telemetry data processing capabilities. The optical and inertial sensors, reaction control system thrusters, and the docking mechanism selected were based on CCP vehicle manufacturer's current and proposed technologies. A significant amount of independent study and tutorial completion was required for this project. Multiple primary source materials were accessed using the NASA Technical Report Server (NTRS) and reference textbooks were borrowed from the JSC Main Library and International Space Station Library. The Trick Simulation Environment and User

  14. Simulation of LMFBR

    SciTech Connect

    Agrawal, A.K.

    1982-01-01

    The title of this session is taken to imply the system-wide thermohydraulic simulation of liquid metal fast breeder reactors (LMFBR). One is interested in predicting the temperatures, pressures, and the coolant flow rates throughout the entire plant including the reactor core, the primary and secondary sodium heat transport circuits, the steam generating system as well as other auxiliary circuits. Such a simulation is needed for (1) scoping studies (i.e., in the pre-design phase of a plant), (2) detailed design development, (3) the safety analysis (post-design development phase), and (4) the operator training and plant operation. This session emphasizes the simulation of LMFBRs for only two key categories of transients: operational disturbances or events and the post-shutdown heat removal.

  15. Real time digital propulsion system simulation for manned flight simulators

    NASA Technical Reports Server (NTRS)

    Mihaloew, J. R.; Hart, C. E.

    1978-01-01

    A real time digital simulation of a STOL propulsion system was developed which generates significant dynamics and internal variables needed to evaluate system performance and aircraft interactions using manned flight simulators. The simulation ran at a real-to-execution time ratio of 8.8. The model was used in a piloted NASA flight simulator program to evaluate the simulation technique and the propulsion system digital control. The simulation is described and results shown. Limited results of the flight simulation program are also presented.

  16. Simulation verification techniques study. Subsystem simulation validation techniques

    NASA Technical Reports Server (NTRS)

    Duncan, L. M.; Reddell, J. P.; Schoonmaker, P. B.

    1974-01-01

    Techniques for validation of software modules which simulate spacecraft onboard systems are discussed. An overview of the simulation software hierarchy for a shuttle mission simulator is provided. A set of guidelines for the identification of subsystem/module performance parameters and critical performance parameters are presented. Various sources of reference data to serve as standards of performance for simulation validation are identified. Environment, crew station, vehicle configuration, and vehicle dynamics simulation software are briefly discussed from the point of view of their interfaces with subsystem simulation modules. A detailed presentation of results in the area of vehicle subsystems simulation modules is included. A list of references, conclusions and recommendations are also given.

  17. Probabilistic Fatigue: Computational Simulation

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2002-01-01

    Fatigue is a primary consideration in the design of aerospace structures for long term durability and reliability. There are several types of fatigue that must be considered in the design. These include low cycle, high cycle, combined for different cyclic loading conditions - for example, mechanical, thermal, erosion, etc. The traditional approach to evaluate fatigue has been to conduct many tests in the various service-environment conditions that the component will be subjected to in a specific design. This approach is reasonable and robust for that specific design. However, it is time consuming, costly and needs to be repeated for designs in different operating conditions in general. Recent research has demonstrated that fatigue of structural components/structures can be evaluated by computational simulation based on a novel paradigm. Main features in this novel paradigm are progressive telescoping scale mechanics, progressive scale substructuring and progressive structural fracture, encompassed with probabilistic simulation. These generic features of this approach are to probabilistically telescope scale local material point damage all the way up to the structural component and to probabilistically scale decompose structural loads and boundary conditions all the way down to material point. Additional features include a multifactor interaction model that probabilistically describes material properties evolution, any changes due to various cyclic load and other mutually interacting effects. The objective of the proposed paper is to describe this novel paradigm of computational simulation and present typical fatigue results for structural components. Additionally, advantages, versatility and inclusiveness of computational simulation versus testing are discussed. Guidelines for complementing simulated results with strategic testing are outlined. Typical results are shown for computational simulation of fatigue in metallic composite structures to demonstrate the

  18. CAPS Simulation Environment Development

    NASA Technical Reports Server (NTRS)

    Murphy, Douglas G.; Hoffman, James A.

    2005-01-01

    The final design for an effective Comet/Asteroid Protection System (CAPS) will likely come after a number of competing designs have been simulated and evaluated. Because of the large number of design parameters involved in a system capable of detecting an object, accurately determining its orbit, and diverting the impact threat, a comprehensive simulation environment will be an extremely valuable tool for the CAPS designers. A successful simulation/design tool will aid the user in identifying the critical parameters in the system and eventually allow for automatic optimization of the design once the relationships of the key parameters are understood. A CAPS configuration will consist of space-based detectors whose purpose is to scan the celestial sphere in search of objects likely to make a close approach to Earth and to determine with the greatest possible accuracy the orbits of those objects. Other components of a CAPS configuration may include systems for modifying the orbits of approaching objects, either for the purpose of preventing a collision or for positioning the object into an orbit where it can be studied or used as a mineral resource. The Synergistic Engineering Environment (SEE) is a space-systems design, evaluation, and visualization software tool being leveraged to simulate these aspects of the CAPS study. The long-term goal of the SEE is to provide capabilities to allow the user to build and compare various CAPS designs by running end-to-end simulations that encompass the scanning phase, the orbit determination phase, and the orbit modification phase of a given scenario. Herein, a brief description of the expected simulation phases is provided, the current status and available features of the SEE software system is reported, and examples are shown of how the system is used to build and evaluate a CAPS detection design. Conclusions and the roadmap for future development of the SEE are also presented.

  19. LSST Operations Simulator

    NASA Astrophysics Data System (ADS)

    Cook, K. H.; Delgado, F.; Miller, M.; Saha, A.; Allsman, R.; Pinto, P.; Gee, P. A.

    2005-12-01

    We have developed an operations simulator for LSST and used it to explore design and operations parameter space for this large etendue telescope and its ten year survey mission. The design is modular, with separate science programs coded in separate modules. There is a sophisticated telescope module with all motions parametrized for ease of testing different telescope capabilities, e.g. effect of acceleration capabilities of various motors on science output. Sky brightness is calculated as a function of moon phase and separation. A sophisticated exposure time calculator has been developed for LSST which is being incorporated into the simulator to allow specification of S/N requirements. All important parameters for the telescope, the site and the science programs are easily accessible in configuration files. Seeing and cloud data from the three candidate LSST sites are used for our simulations. The simulator has two broad categories of science proposals: sky coverage and transient events. Sky coverage proposals base their observing priorities on a required number of observations for each field in a particular filter with specified conditions (maximum seeing, sky brightness, etc) and one is used for a weak lensing investigation. Transient proposals are highly configurable. A transient proposal can require sequential, multiple exposures in various filters with a specified sequence of filters, and require a particular cadence for multiple revisits to complete an observation sequence. Each science proposal ranks potential observations based upon the internal logic of that proposal. We present the results of a variety of mixed science program observing simulations, showing how varied programs can be carried out simultaneously, with many observations serving multiple science goals. The simulator has shown that LSST can carry out its multiple missions under a variety of conditions. KHC's work was performed under the auspices of the US DOE, NNSA by the Univ. of California

  20. Simulations of vortex generators

    NASA Technical Reports Server (NTRS)

    Koumoutsakos, P.

    1995-01-01

    We are interested in the study, via direct numerical simulations, of active vortex generators. Vortex generators may be used to modify the inner part of the boundary layer or to control separation thus enhancing the performance and maneuverability of aerodynamic configurations. We consider generators that consist of a surface cavity elongated in the stream direction and partially covered with a moving lid that at rest lies flush with the boundary. Streamwise vorticity is generated and ejected due to the oscillatory motion of the lid. The present simulations complement relevant experimental investigations of active vortex generators at NASA Ames and Stanford University (Saddoughi, 1994, and Jacobson and Reynolds, 1993). Jacobson and Reynolds (1993) used a piezoelectric device in water, allowing for small amplitude high frequency oscillations. They placed the lid asymmetrically on the cavity and observed a strong outward velocity at the small gap of the cavity. Saddoughi used a larger mechanically driven device in air to investigate this flow and he observed a jet emerging from the wide gap of the configuration, contrary to the findings of Jacobson and Reynolds. Our task is to simulate the flows generated by these devices and to conduct a parametric study that would help us elucidate the physical mechanisms present in the flow. Conventional computational schemes encounter difficulties when simulating flows around complex configurations undergoing arbitrary motions. Here we present a formulation that achieves this task on a purely Lagrangian frame by extending the formulation presented by Koumoutsakos, Leonard and Pepin (1994). The viscous effects are taken into account by modifying the strength of the particles, whereas fast multipole schemes employing hundreds of thousands of particles allow for high resolution simulations. The results of the present simulations would help us assess some of the effects of three-dimensionality in experiments and investigate the role

  1. Charming VPythong Simulations

    NASA Astrophysics Data System (ADS)

    Pepin, Eric W.; Olenick, R. P.

    2006-12-01

    The University of Dallas Department of Physics requires a sophomore-year computational course for all physics majors. The course introduces students to modeling classical and quantum systems with appropriate numerical methods. Students, as part of a course project, have developed charming visual simulations that have then been refined and used to educate subsequent undergraduates. In this poster session we will present several VPython simulations ranging from baseball pitches as viewed from around the field to quantum scattering and from galaxy formation to dielectric breakdown. We will discuss how they are used to make underlying concepts in physics more understandable.

  2. Visual simulation of radiographs

    SciTech Connect

    Laguna, G.

    1985-01-18

    A method for computer simulation of radiographs has been added to the LLNL version of the solid modeler TIPS-1 (Technical Information Processing System-1). This new tool will enable an engineer to compare an actual radiograph of a solid to its computer-generated counterpart. The appearance of discrepancies between the two can be an indication of flaws in the solid object. Simulated radiographs can also be used to preview the placement of x-ray sources to focus on areas of concern before actual radiographs are made.

  3. Terascale Optimal PDE Simulations

    SciTech Connect

    David Keyes

    2009-07-28

    The Terascale Optimal PDE Solvers (TOPS) Integrated Software Infrastructure Center (ISIC) was created to develop and implement algorithms and support scientific investigations performed by DOE-sponsored researchers. These simulations often involve the solution of partial differential equations (PDEs) on terascale computers. The TOPS Center researched, developed and deployed an integrated toolkit of open-source, optimal complexity solvers for the nonlinear partial differential equations that arise in many DOE application areas, including fusion, accelerator design, global climate change and reactive chemistry. The algorithms created as part of this project were also designed to reduce current computational bottlenecks by orders of magnitude on terascale computers, enabling scientific simulation on a scale heretofore impossible.

  4. Faster simulation plots

    NASA Technical Reports Server (NTRS)

    Fowell, Richard A.

    1989-01-01

    Most simulation plots are heavily oversampled. Ignoring unnecessary data points dramatically reduces plot time with imperceptible effect on quality. The technique is suited to most plot devices. The departments laser printer's speed was tripled for large simulation plots by data thinning. This reduced printer delays without the expense of a faster laser printer. Surpisingly, it saved computer time as well. All plot data are now thinned, including PostScript and terminal plots. The problem, solution, and conclusions are described. The thinning algorithm is described and performance studies are presented. To obtain FORTRAN 77 or C source listings, mail a SASE to the author.

  5. Compassion for simulation.

    PubMed

    Kenny, Gerard

    2016-01-01

    This topic for debate explores how simulation based education has become an area where Higher Education providers look to deliver on an agenda of recruiting, educating and assessing for compassion. This paper offers that rather than SBE being a forum for developing and promoting compassion it may actually be achieving the opposite both for those we educate and those they in turn care for. It does this through introducing two ideas, near enemies and Jung's shadow and uses these ideas to explore our understanding and expression of compassion through simulation.

  6. Tether Dynamics Simulation

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The proceedings of the conference are presented. The objective was to provide a forum for the discussion of the structure and status of existing computer programs which are used to simulate the dynamics of a variety of tether applications in space. A major topic was different simulation models and the process of validating them. Guidance on future work in these areas was obtained from a panel discussion; the panel was composed of resource and technical managers and dynamic analysts in the tether field. The conclusions of this panel are also presented.

  7. Emotional Intelligence and Simulation.

    PubMed

    McKinley, Sophia K; Phitayakorn, Roy

    2015-08-01

    Emotional intelligence (EI) is an established concept in the business literature with evidence that it is an important factor in determining career achievement. There is increasing interest in the role that EI has in medical training, but it is still a nascent field. This article reviews the EI literature most relevant to surgical training and proposes that simulation offers many benefits to the development of EI. Although there are many unanswered questions, it is expected that future research will demonstrate the effectiveness of using simulation to develop EI within surgery.

  8. History Microcomputer Simulations: An Update.

    ERIC Educational Resources Information Center

    Sargent, James E.

    1985-01-01

    This article summarizes seven currently available microcomputer simulations for history. The seven included are: Government Simulations (Prentice-Hall, 1984), Nomination (Brady Company, 1984), Tigers in the Snow (Strategic Simulations, 1981), Lincoln's Decisions (Educational Activities, 1982), Watergate Simulation (Social Science Research and…

  9. Simulation in International Relations Education.

    ERIC Educational Resources Information Center

    Starkey, Brigid A.; Blake, Elizabeth L.

    2001-01-01

    Discusses the educational implications of simulations in international relations. Highlights include the development of international relations simulations; the role of technology; the International Communication and Negotiation Simulations (ICONS) project at the University of Maryland; evolving information technology; and simulating real-world…

  10. Simulating neural systems with Xyce.

    SciTech Connect

    Schiek, Richard Louis; Thornquist, Heidi K.; Mei, Ting; Warrender, Christina E.; Aimone, James Bradley; Teeter, Corinne; Duda, Alex M.

    2012-12-01

    Sandias parallel circuit simulator, Xyce, can address large scale neuron simulations in a new way extending the range within which one can perform high-fidelity, multi-compartment neuron simulations. This report documents the implementation of neuron devices in Xyce, their use in simulation and analysis of neuron systems.

  11. Variational calculation of transport coefficients in diffusive lattice gases

    NASA Astrophysics Data System (ADS)

    Arita, Chikashi; Krapivsky, P. L.; Mallick, Kirone

    2017-03-01

    A diffusive lattice gas is characterized by the diffusion coefficient depending only on the density. The Green-Kubo formula for diffusivity can be represented as a variational formula, but even when the equilibrium properties of a lattice gas are analytically known, the diffusion coefficient can be computed only in the exceptional situation when the lattice gas is gradient. In the general case, minimization over an infinite-dimensional space is required. We propose an approximation scheme based on minimizing over finite-dimensional subspaces of functions. The procedure is demonstrated for one-dimensional generalized exclusion processes in which each site can accommodate at most two particles. Our analytical predictions provide upper bounds for the diffusivity that are very close to simulation results throughout the entire density range. We also analyze nonequilibrium density profiles for finite chains coupled to reservoirs. The predictions for the profiles are in excellent agreement with simulations.

  12. Multipebble Simulations for Alternating Automata

    NASA Astrophysics Data System (ADS)

    Clemente, Lorenzo; Mayr, Richard

    We study generalized simulation relations for alternating Büchi automata (ABA), as well as alternating finite automata. Having multiple pebbles allows the Duplicator to "hedge her bets" and delay decisions in the simulation game, thus yielding a coarser simulation relation. We define (k 1,k 2)-simulations, with k 1/k 2 pebbles on the left/right, respectively. This generalizes previous work on ordinary simulation (i.e., (1,1)-simulation) for nondeterministic Büchi automata (NBA)[4] in and ABA in [5], and (1,k)-simulation for NBA in [3].

  13. Trajectory constraints in qualitative simulation

    SciTech Connect

    Brajnik, G.; Clancy, D.J.

    1996-12-31

    We present a method for specifying temporal constraints on trajectories of dynamical systems and enforcing them during qualitative simulation. This capability can be used to focus a simulation, simulate non-autonomous and piecewise-continuous systems, reason about boundary condition problems and incorporate observations into the simulation. The method has been implemented in TeQSIM, a qualitative simulator that combines the expressive power of qualitative differential equations with temporal logic. It interleaves temporal logic model checking with the simulation to constrain and refine the resulting predicted behaviors and to inject discontinuous changes into the simulation.

  14. Evaluation Training: Simulation Exercises.

    ERIC Educational Resources Information Center

    Smith, Carl B.; Farr, Roger

    The preparation of this simulation material package is guided by the concept of an evaluator as a decision-maker, based on the definition of evaluation as a continuous assessment concerned with answering decision-making questions. The continuous concept of evaluation is based on the model created by Egon Guba and Daniel Stufflebeam, named by its…

  15. Quantitative Simulation Games

    NASA Astrophysics Data System (ADS)

    Černý, Pavol; Henzinger, Thomas A.; Radhakrishna, Arjun

    While a boolean notion of correctness is given by a preorder on systems and properties, a quantitative notion of correctness is defined by a distance function on systems and properties, where the distance between a system and a property provides a measure of "fit" or "desirability." In this article, we explore several ways how the simulation preorder can be generalized to a distance function. This is done by equipping the classical simulation game between a system and a property with quantitative objectives. In particular, for systems that satisfy a property, a quantitative simulation game can measure the "robustness" of the satisfaction, that is, how much the system can deviate from its nominal behavior while still satisfying the property. For systems that violate a property, a quantitative simulation game can measure the "seriousness" of the violation, that is, how much the property has to be modified so that it is satisfied by the system. These distances can be computed in polynomial time, since the computation reduces to the value problem in limit average games with constant weights. Finally, we demonstrate how the robustness distance can be used to measure how many transmission errors are tolerated by error correcting codes.

  16. Simulating the Eucaryotic Chromosome.

    ERIC Educational Resources Information Center

    Spencer, Leo E.

    1985-01-01

    The use of simple materials to illustrate complex biological concepts provides benefits to all students, particularly the visually handicapped. A list of materials needed and discussion of procedures used are given for (1) a nucleosome simulation and (2) a supercoiled model of condensed DNA. (DH)

  17. Data Systems Dynamic Simulator

    NASA Technical Reports Server (NTRS)

    Rouff, Christopher; Clark, Melana; Davenport, Bill; Message, Philip

    1993-01-01

    The Data System Dynamic Simulator (DSDS) is a discrete event simulation tool. It was developed for NASA for the specific purpose of evaluating candidate architectures for data systems of the Space Station era. DSDS provides three methods for meeting this requirement. First, the user has access to a library of standard pre-programmed elements. These elements represent tailorable components of NASA data systems and can be connected in any logical manner. Secondly, DSDS supports the development of additional elements. This allows the more sophisticated DSDS user the option of extending the standard element set. Thirdly, DSDS supports the use of data streams simulation. Data streams is the name given to a technique that ignores packet boundaries, but is sensitive to rate changes. Because rate changes are rare compared to packet arrivals in a typical NASA data system, data stream simulations require a fraction of the CPU run time. Additionally, the data stream technique is considerably more accurate than another commonly-used optimization technique.

  18. Simulations of laser thrombolysis

    SciTech Connect

    Chapyak, E.J.; Godwin, R.P.

    1999-03-01

    The authors have shown that bubble expansion and collapse near the interface between two materials with modest property differences produces jet-like interpenetration of the two materials. The bubble dynamics at a water-viscous fluid interface is compared with that at the interface of water with a weak elastic-plastic material. The authors find that, despite rather similar behavior during bubble growth and the initial portion of bubble collapse, the terminal jetting behavior is quite different, even in direction. The elastic-plastic properties chosen realistically represent real and surrogate thrombus. Simulations using the elastic-plastic model quantitatively agree with laboratory thrombolysis mass removal experiments. In the earlier simulations of laboratory experiments, walls have been remote so as to not effect the dynamics. Here the authors present two-dimensional simulations of thrombolysis with water over elastic-plastic surrogate thrombus in a geometry representative of the clinical situation. The calculations include thin cylindrical elastic walls with properties and dimensions appropriate for arteries. The presence of these artery walls does not substantially change the interface jetting predicted in unconfined simulations.

  19. Helicopter simulator qualification

    NASA Technical Reports Server (NTRS)

    Hampson, Brian

    1992-01-01

    CAE has extensive experience in building helicopter simulators and has participated in group working sessions for fixed-wing advisory circulars. Against this background, issues that should be addressed in establishing helicopter approval criteria were highlighted. Some of these issues are not immediately obvious and may, indeed, be more important than the criteria a themselves.

  20. Plasma Theory and Simulation.

    DTIC Science & Technology

    1981-12-31

    Bill Nevins, LLNL Use of the ZED postprocessor. Oct 9 Tom Crystal Kinetic simulations of Tokamak TEM Oct 23 Niels Otani The AIC instability...Ion test oarticles advanced in the equilibrium fields do maintain their initial distri- bution function, as desired. The next step is to be wholly

  1. Computer Simulation of Mutagenesis.

    ERIC Educational Resources Information Center

    North, J. C.; Dent, M. T.

    1978-01-01

    A FORTRAN program is described which simulates point-substitution mutations in the DNA strands of typical organisms. Its objective is to help students to understand the significance and structure of the genetic code, and the mechanisms and effect of mutagenesis. (Author/BB)

  2. Service Learning and Simulations

    ERIC Educational Resources Information Center

    Jenkins, Shannon

    2010-01-01

    Both service learning and simulations have been shown to positively impact student outcomes, but they are not often used together. This article examines how to effectively combine these active learning styles to reap the benefits of both. After examining a case in which the two were combined and the impact this approach had on student evaluations…

  3. Introduction. Biomolecular simulation

    PubMed Central

    Mulholland, Adrian J.

    2008-01-01

    ‘Everything that living things do can be understood in terms of the jigglings and wigglings of atoms’ as Richard Feynman provocatively stated nearly 50 years ago. But how can we ‘see’ this wiggling and jiggling and understand how it drives biology? Increasingly, computer simulations of biological macromolecules are helping to meet this challenge. PMID:18826912

  4. Human Simulated Diving Experiments.

    ERIC Educational Resources Information Center

    Bruce, David S.; Speck, Dexter F.

    1979-01-01

    This report details several simulated divinq experiments on the human. These are suitable for undergraduate or graduate laboratories in human or environmental physiology. The experiment demonstrates that a diving reflex is precipitated by both facial cooling and apnea. (Author/RE)

  5. Simulation Insights Using "R"

    ERIC Educational Resources Information Center

    Kostadinov, Boyan

    2013-01-01

    This article attempts to introduce the reader to computational thinking and solving problems involving randomness. The main technique being employed is the Monte Carlo method, using the freely available software "R for Statistical Computing." The author illustrates the computer simulation approach by focusing on several problems of…

  6. Parallel Dislocation Simulator

    SciTech Connect

    2006-10-30

    ParaDiS is software capable of simulating the motion, evolution, and interaction of dislocation networks in single crystals using massively parallel computer architectures. The software is capable of outputting the stress-strain response of a single crystal whose plastic deformation is controlled by the dislocation processes.

  7. Simulation of phase structures

    SciTech Connect

    Lawson, J.

    1995-04-20

    This memo outlines a procedure developed by the author to extract information from phase measurements and produce a simulated phase structure for use in modeling optical systems, including characteristic optics for the Beamlet and NIF laser systems. The report includes an IDL program listing.

  8. Simulator Test and Evaluation

    DTIC Science & Technology

    2009-01-13

    control system (AFCS) ON and OFF. Flight control axes which include a trim system will be tested with both TRIM ON and OFF and stability augmentation system (SAS...Flight Test Manual HQ Handling Qualities M&S Modeling and Simulation SAS Stability Augmentation System SCAS Stability and Control

  9. Imitation, Simulation, and Schizophrenia

    PubMed Central

    Park, Sohee; Matthews, Natasha; Gibson, Crystal

    2008-01-01

    The social significance of imitation is that it provides internal tools for understanding the actions of others by simulating or forming internal representations of these actions. Imitation plays a central role in human social behavior by mediating diverse forms of social learning. However, imitation and simulation ability in schizophrenia has not been adequately addressed. The major aim of the present study was to investigate imitation ability in schizophrenia patients and healthy individuals by examining simple motor imitation that involved the replication of meaningless manual and oral gestures, and the imitation of emotional facial expressions, which has implications for mentalizing. A secondary aim of the present study was to investigate the relationships among imitation ability, social functioning, and working memory. Subjects were asked to mimic hand gestures, mouth movements, and facial expressions of others, online. Clinical symptoms, social competence, and working memory were also assessed. Patients with schizophrenia were significantly impaired on all imitation tasks. Imitation errors were significantly correlated with reduced social competence and increased negative symptoms. However, imitation ability was only weakly associated with working memory. To summarize, the present study examined the ability of patients with schizophrenia to imitate the behaviors demonstrated by others. The results indicate a fundamental impairment in imitation ability in schizophrenia and implicate a possible difficulty in simulation. Further research to determine the neural and developmental origins of this difficulty could be extremely helpful in elucidating the role of simulation in schizophrenia and to establish the complex relationships among mental representation, imitation, and social cognition. PMID:18499703

  10. Simulated proteinuria and haematuria.

    PubMed

    Englis, M; Martinek, V; Jirka, J; Schück, O; Velická, V

    1983-01-01

    In nephrology, like in other branches of medicine, falsification is motivated by a desire for profit or is an expression of some mental disorder. Three cases are described in which artificial proteinuria and haematuria were diagnosed by agarose gel electrophoresis of urinary proteins and a simulation and aggravation of renal disease was disclosed.

  11. SPASIM: A Spacecraft Simulator

    NASA Technical Reports Server (NTRS)

    Liceaga, Carlos A.

    1997-01-01

    The SPAcecraft SIMulator (SPASIM) simulates the functions and resources of a spacecraft to quickly perform conceptual design (Phase A) trade-off and sensitivity analyses and uncover any operational bottlenecks during any part of the mission. Failure modes and operational contingencies can be evaluated allowing operational planning (what-if scenarios) and optimization for a range of mission scenarios. The payloads and subsystems are simulated, using a hierarchy of graphical models, in terms of how their functions affect resources such as propellant, power, and data. Any of the inputs and outputs of the payloads and subsystems can be plotted during the simulation or stored in a file so they can be used by other programs. Most trade-off analyses, including those that compare current versus advanced technology, can be performed by changing values in the parameter menus. However, when a component is replaced by one with a different functional architecture, its graphical model can also be modified or replaced by drawing from a component library. SPASIM has been validated using several spacecraft designs that were at least at the Critical Design Review level. The user and programmer guide, including figures, is available on line as a hypertext document. This is an easy-to-use and expandable tool which is based on MATLAB(R) and SIMULINK(R). It runs on Silicon Graphics Inc. workstations and personal computers with Windows 95(TM) or NT(TM).

  12. Smoothed Particle Hydrodynamic Simulator

    SciTech Connect

    2016-10-05

    This code is a highly modular framework for developing smoothed particle hydrodynamic (SPH) simulations running on parallel platforms. The compartmentalization of the code allows for rapid development of new SPH applications and modifications of existing algorithms. The compartmentalization also allows changes in one part of the code used by many applications to instantly be made available to all applications.

  13. Solar simulator mirror refurbishment

    NASA Technical Reports Server (NTRS)

    Leverton, W. R.

    1974-01-01

    Solar simulator mirrors were refurbished. Two different refurbishment methods were employed. In the first, the electroformed mirror replica was removed from the casting and replaced with a new mirror replica. In the second, only the aluminized surface, with its protective overcoat, was removed from the mirror and replaced after cleaning of the nickel surface.

  14. ICAAS piloted simulation results

    NASA Astrophysics Data System (ADS)

    Landy, R. J.; Halski, P. J.; Meyer, R. P.

    1994-05-01

    This paper reports piloted simulation results from the Integrated Control and Avionics for Air Superiority (ICAAS) piloted simulation evaluations. The program was to develop, integrate, and demonstrate critical technologies which will enable United States Air Force tactical fighter 'blue' aircraft to achieve superiority and survive when outnumbered by as much as four to one by enemy aircraft during air combat engagements. Primary emphasis was placed on beyond visual range (BVR) combat with provisions for effective transition to close-in combat. The ICAAS system was developed and tested in two stages. The first stage, called low risk ICAAS, was defined as employing aircraft and avionics technology with an initial operational date no later than 1995. The second stage, called medium risk ICAAS, was defined as employing aircraft and avionics technology with an initial operational date no later than 1998. Descriptions of the low risk and medium risk simulation configurations are given. Normalized (unclassified) results from both the low risk and medium risk ICAAS simulations are discussed. The results show the ICAAS system provided a significant improvement in air combat performance when compared to a current weapon system. Data are presented for both current generation and advanced fighter aircraft. The ICAAS technologies which are ready for flight testing in order to transition to the fighter fleet are described along with technologies needing additional development.

  15. 2007 Simulation Education Summit

    DTIC Science & Technology

    2008-03-01

    simulation: a revolution in procedural training. Chest. 2001 Oct;120(4):1333-9. 11. Mayo PH, Hackney JE, Mueck JT, Ribaudo V, Schneider RF. Achieving...training. Chest. 2001 Oct;120(4):1333-9. 27. Mayo PH, Hackney JE, Mueck JT, Ribaudo V, Schneider RF. Achieving house staff competence in emergency

  16. Juno Mission Simulation

    NASA Technical Reports Server (NTRS)

    Lee, Meemong; Weidner, Richard J.

    2008-01-01

    The Juno spacecraft is planned to launch in August of 2012 and would arrive at Jupiter four years later. The spacecraft would spend more than one year orbiting the planet and investigating the existence of an ice-rock core; determining the amount of global water and ammonia present in the atmosphere, studying convection and deep- wind profiles in the atmosphere; investigating the origin of the Jovian magnetic field, and exploring the polar magnetosphere. Juno mission management is responsible for mission and navigation design, mission operation planning, and ground-data-system development. In order to ensure successful mission management from initial checkout to final de-orbit, it is critical to share a common vision of the entire mission operation phases with the rest of the project teams. Two major challenges are 1) how to develop a shared vision that can be appreciated by all of the project teams of diverse disciplines and expertise, and 2) how to continuously evolve a shared vision as the project lifecycle progresses from formulation phase to operation phase. The Juno mission simulation team addresses these challenges by developing agile and progressive mission models, operation simulations, and real-time visualization products. This paper presents mission simulation visualization network (MSVN) technology that has enabled a comprehensive mission simulation suite (MSVN-Juno) for the Juno project.

  17. Teleoperator docking simulation

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, M.; Brye, R. G.

    1974-01-01

    A simulation study is described of the translation, station keeping and final approach segments of the teleoperator implemented at MSFC. An effort is made to identify the teleoperator visual system design parameters which influence operator performance and to determine human factors design requirements for free flying teleoperators.

  18. Battery Particle Simulation

    SciTech Connect

    2014-09-15

    Two simulations show the differences between a battery being drained at a slower rate, over a full hour, versus a faster rate, only six minutes (a tenth of an hour). In both cases battery particles go from being fully charged (green) to fully drained (red), but there are significant differences in the patterns of discharge based on the rate.

  19. Fault-Mechanism Simulator

    ERIC Educational Resources Information Center

    Guyton, J. W.

    1972-01-01

    An inexpensive, simple mechanical model of a fault can be produced to simulate the effects leading to an earthquake. This model has been used successfully with students from elementary to college levels and can be demonstrated to classes as large as thirty students. (DF)

  20. Enabling immersive simulation.

    SciTech Connect

    McCoy, Josh; Mateas, Michael; Hart, Derek H.; Whetzel, Jonathan; Basilico, Justin Derrick; Glickman, Matthew R.; Abbott, Robert G.

    2009-02-01

    The object of the 'Enabling Immersive Simulation for Complex Systems Analysis and Training' LDRD has been to research, design, and engineer a capability to develop simulations which (1) provide a rich, immersive interface for participation by real humans (exploiting existing high-performance game-engine technology wherever possible), and (2) can leverage Sandia's substantial investment in high-fidelity physical and cognitive models implemented in the Umbra simulation framework. We report here on these efforts. First, we describe the integration of Sandia's Umbra modular simulation framework with the open-source Delta3D game engine. Next, we report on Umbra's integration with Sandia's Cognitive Foundry, specifically to provide for learning behaviors for 'virtual teammates' directly from observed human behavior. Finally, we describe the integration of Delta3D with the ABL behavior engine, and report on research into establishing the theoretical framework that will be required to make use of tools like ABL to scale up to increasingly rich and realistic virtual characters.

  1. Simulations of immersion lithography

    NASA Astrophysics Data System (ADS)

    Bai, Min; Lei, Junjiang; Zhang, Lin; Shiely, James P.

    2005-05-01

    Immersion lithography has been regarded as the most viable contender to extend the resolution capability of optical lithography using 193nm wavelength. In parallel with the tremendous effort of overcoming the engineering challenges in immersion, support from modeling and simulations is strongly needed. Although immersion simulation has become available through a number of simulation tools, we need to investigate the model generation and its compatibility within the context of full-chip optical proximity correction (OPC). In this paper, we will describe the physics of a full vector model that is necessary for the high NA optical modeling under immersion. In this full vector model, we consider not only the plane wave decomposition as light travels from the mask to wafer plane, but also the refraction, transmission and reflection of light through a thin film stack on the wafer. We integrated this comprehensive vector model into Synopsys OPC modeling tool ProGen. Through ProGen simulation results, we will discuss several important merits of immersion lithography, as well as the full portability of immersion models into OPC process flow.

  2. Bolometer Simulation Using SPICE

    NASA Technical Reports Server (NTRS)

    Jones, Hollis H.; Aslam, Shahid; Lakew, Brook

    2004-01-01

    A general model is presented that assimilates the thermal and electrical properties of the bolometer - this block model demonstrates the Electro-Thermal Feedback (ETF) effect on the bolometers performance. This methodology is used to construct a SPICE model that by way of analogy combines the thermal and electrical phenomena into one simulation session. The resulting circuit diagram is presented and discussed.

  3. Ion trap simulation tools.

    SciTech Connect

    Hamlet, Benjamin Roger

    2009-02-01

    Ion traps present a potential architecture for future quantum computers. These computers are of interest due to their increased power over classical computers stemming from the superposition of states and the resulting capability to simultaneously perform many computations. This paper describes a software application used to prepare and visualize simulations of trapping and maneuvering ions in ion traps.

  4. Numerical Propulsion System Simulation

    NASA Technical Reports Server (NTRS)

    Naiman, Cynthia

    2006-01-01

    The NASA Glenn Research Center, in partnership with the aerospace industry, other government agencies, and academia, is leading the effort to develop an advanced multidisciplinary analysis environment for aerospace propulsion systems called the Numerical Propulsion System Simulation (NPSS). NPSS is a framework for performing analysis of complex systems. The initial development of NPSS focused on the analysis and design of airbreathing aircraft engines, but the resulting NPSS framework may be applied to any system, for example: aerospace, rockets, hypersonics, power and propulsion, fuel cells, ground based power, and even human system modeling. NPSS provides increased flexibility for the user, which reduces the total development time and cost. It is currently being extended to support the NASA Aeronautics Research Mission Directorate Fundamental Aeronautics Program and the Advanced Virtual Engine Test Cell (AVETeC). NPSS focuses on the integration of multiple disciplines such as aerodynamics, structure, and heat transfer with numerical zooming on component codes. Zooming is the coupling of analyses at various levels of detail. NPSS development includes capabilities to facilitate collaborative engineering. The NPSS will provide improved tools to develop custom components and to use capability for zooming to higher fidelity codes, coupling to multidiscipline codes, transmitting secure data, and distributing simulations across different platforms. These powerful capabilities extend NPSS from a zero-dimensional simulation tool to a multi-fidelity, multidiscipline system-level simulation tool for the full development life cycle.

  5. Mars Surface Simulations

    NASA Astrophysics Data System (ADS)

    Nørnberg, Per; Merrison, Jonathan P.; Gunnlaugsson, Haraldur P.

    2010-05-01

    Laboratory simulations of the Martian surface are of importance to broaden scientific understanding of the physical processes, but also in order to develop the technology necessary for exploration of the planet. The Mars Simulation Laboratory at Aarhus University [1] has been involved in such simulations for around ten years and has developed several experimental facilities for carrying out science or instrument testing under conditions similar to those at the Martian surface, specifically low pressure, low temperature and importantly recreating the wind flow environment and dust suspension (reproducing the Martian dusty aerosol) using Mars analogue material [2]. The science involved in this simulation work has covered a broad spectrum including, erosion induced mineralogy/chemistry, particulate electrification, magnetic properties of Martian dust, biological survival, UV induced chemistry/mineralogy (using a solar simulator), adhesion/cohesion processes and the wind driven transport of dust and sand [3,4]. With regard to technology the wind tunnel facilities have been used in the development of the latest wind and dust sensing instrumentation [5,6]. With support from the European Space Agency (ESA) and Danish national funding an advanced Mars simulation facility has recently been constructed (2009). This wind tunnel facility has a cross section of 2 x 1 m and a length of 8 m, a temperature range down to below -120C, wind speeds in excess of 20m/s, and automated dust control. With a range of (specialised) sensing instrumentation it provides the opportunity to perform a new generation of scientific experiments and allow testing and technology development in the most realistic and rigorous environment. As well as being available for the space agencies, this facility will be open to all potential scientific collaborators. Also European planetary scientists may benefit from support through the EU Europlanet FP7 networking programme. For more information on access

  6. Simulations of Solar Jets

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-02-01

    Formation of a coronal jet from twisted field lines that have reconnected with the ambient field. The colors show the radial velocity of the plasma. [Adapted from Szente et al. 2017]How do jets emitted from the Suns surface contribute to its corona and to the solar wind? In a recent study, a team of scientists performed complex three-dimensional simulations of coronal jets to answer these questions.Small ExplosionsCoronal jets are relatively small eruptions from the Suns surface, with heights of roughly 100 to 10,000 km, speeds of 10 to 1,000 km/s, and lifetimes of a few minutes to around ten hours. These jets are constantly present theyre emitted even from the quiet Sun, when activity is otherwise low and weve observed them with a fleet of Sun-watching space telescopes spanning the visible, extreme ultraviolet (EUV), and X-ray wavelength bands.A comparison of simulated observations based on the authors model (left panels) to actual EUV and X-ray observations of jets (right panels). [Szente et al. 2017]Due to their ubiquity, we speculate that these jets might contribute to heating the global solar corona (which is significantly hotter than the surface below it, a curiosity known as the coronal heating problem). We can also wonder what role these jets might play in driving the overall solar wind.Launching a JetLed by Judit Szente (University of Michigan), a team of scientists has explored the impact of coronal jets on the global corona and solar wind with a series of numerical simulations. Szente and collaborators used three-dimensional, magnetohydrodynamic simulations that provide realistic treatment of the solar atmosphere, the solar wind acceleration, and the complexities of heat transfer throughout the corona.In the authors simulations, a jet is initiated as a magnetic dipole rotates at the solar surface, winding up field lines. Magnetic reconnection between the twisted lines and the background field then launches the jet from the dense and hot solar

  7. Molecular Simulations in Astrobiology

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Wilson, Michael A.; Schweighofer, Karl; Chipot, Christophe; New, Michael H.

    2000-01-01

    One of the main goals of astrobiology is to understand the origin of cellular life. The most direct approach to this problem is to construct laboratory models of protocells. Such efforts, currently underway in the NASA Astrobiology Program, are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures that are capable of performing protocellular functions. Many of these functions, such as importing nutrients, capturing energy and responding to changes in the environment, are carried out by proteins bound to membranes. We use computer simulations to address the following questions about these proteins: (1) How do small proteins self-organize into ordered structures at water-membrane interfaces and insert into membranes? (2) How do peptides form membrane-spanning structures (e.g. channels)? (3) By what mechanisms do such structures perform their functions? The simulations are performed using the molecular dynamics method. In this method, Newton's equations of motion for each atom in the system are solved iteratively. At each time step, the forces exerted on each atom by the remaining atoms are evaluated by dividing them into two parts. Short-range forces are calculated in real space while long-range forces are evaluated in reciprocal space, using a particle-mesh algorithm which is of order O(NInN). With a time step of 2 femtoseconds, problems occurring on multi-nanosecond time scales (10(exp 6)-10(exp 8) time steps) are accessible. To address a broader range of problems, simulations need to be extended by three orders of magnitude, which requires algorithmic improvements and codes scalable to a large number of processors. Work in this direction is in progress. Two series of simulations are discussed. In one series, it is shown that nonpolar peptides, disordered in water, translocate to the nonpolar interior of the membrane and fold into helical structures (see Figure). Once in the membrane, the peptides

  8. NASA Lunar Regolith Simulant Program

    NASA Technical Reports Server (NTRS)

    Edmunson, J.; Betts, W.; Rickman, D.; McLemore, C.; Fikes, J.; Stoeser, D.; Wilson, S.; Schrader, C.

    2010-01-01

    Lunar regolith simulant production is absolutely critical to returning man to the Moon. Regolith simulant is used to test hardware exposed to the lunar surface environment, simulate health risks to astronauts, practice in situ resource utilization (ISRU) techniques, and evaluate dust mitigation strategies. Lunar regolith simulant design, production process, and management is a cooperative venture between members of the NASA Marshall Space Flight Center (MSFC) and the U.S. Geological Survey (USGS). The MSFC simulant team is a satellite of the Dust group based at Glenn Research Center. The goals of the cooperative group are to (1) reproduce characteristics of lunar regolith using simulants, (2) produce simulants as cheaply as possible, (3) produce simulants in the amount needed, and (4) produce simulants to meet users? schedules.

  9. Deep depth undex simulator

    SciTech Connect

    Higginbotham, R. R.; Malakhoff, A.

    1985-01-29

    A deep depth underwater simulator is illustrated for determining the dual effects of nuclear type underwater explosion shockwaves and hydrostatic pressures on a test vessel while simulating, hydrostatically, that the test vessel is located at deep depths. The test vessel is positioned within a specially designed pressure vessel followed by pressurizing a fluid contained between the test and pressure vessels. The pressure vessel, with the test vessel suspended therein, is then placed in a body of water at a relatively shallow depth, and an explosive charge is detonated at a predetermined distance from the pressure vessel. The resulting shockwave is transmitted through the pressure vessel wall so that the shockwave impinging on the test vessel is representative of nuclear type explosive shockwaves transmitted to an underwater structure at great depths.

  10. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  11. Black Hole Simulation

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This graphic shows the computer simulation of a black hole from start to finish. Plasma is falling slowly toward the black hole in a (at the upper left). The plasma has a magnetic field, shown by the white lines. It picks up speed as it falls toward the hole in b (at the upper right), c (lower left) and d (lower right). However, the rotating black hole twists up space itself (and the magnetic field lines) and ejects electromagnetic power along the north and south poles above the black hole. The red and white color shows the immense electromagnetic power output, which eventually will pick up particles and form squirting jets. This simulation was conducted using supercomputers at Japan's National Institute for Fusion Science.

  12. Compressed quantum simulation

    SciTech Connect

    Kraus, B.

    2014-12-04

    Here, I summarize the results presented in B. Kraus, Phys. Rev. Lett. 107, 250503 (2011). Recently, it has been shown that certain circuits, the so-called match gate circuits, can be compressed to an exponentially smaller universal quantum computation. We use this result to demonstrate that the simulation of a 1-D Ising chain consisting of n qubits can be performed on a universal quantum computer running on only log(n) qubits. We show how the adiabatic evolution can be simulated on this exponentially smaller system and how the magnetization can be measured. Since the Ising model displays a quantum phase transition, this result implies that a quantum phase transition of a very large system can be observed with current technology.

  13. The Umbra Simulation Framework

    SciTech Connect

    GOTTLIEB,ERIC; HARRIGAN,RAYMOND W.; MCDONALD,MICHAEL J.; OPPEL III,FRED J.; XAVIER,PATRICK G.

    2001-06-01

    Umbra is a new Sandia-developed modeling and simulation framework. The Umbra framework allows users to quickly build models and simulations for intelligent system development, analysis, experimentation, and control and supports tradeoff analyses of complex robotic systems, device, and component concepts. Umbra links together heterogeneous collections of modeling tools. The models in Umbra include 3D geometry and physics models of robots, devices and their environments. Model components can be built with varying levels of fidelity and readily switched to allow models built with low fidelity for conceptual analysis to be gradually converted to high fidelity models for later phase detailed analysis. Within control environments, the models can be readily replaced with actual control elements. This paper describes Umbra at a functional level and describes issues that Sandia uses Umbra to address.

  14. Electromagnetic Gyrokinetic Simulations

    SciTech Connect

    Wan, W

    2003-11-19

    A new electromagnetic kinetic electron {delta} particle simulation model has been demonstrated to work well at large values of plasma {beta} times the ion-to-electron mass ratio. The simulation is three-dimensional using toroidal flux-tube geometry and includes electron-ion collisions. The model shows accurate shear Alfven wave damping and microtearing physics. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary, even though the linear behavior of the zonal flow is not significantly affected by kinetic electrons. zonal fields are found to be very weak, consistent with theoretical predictions for {beta} below the kinetic ballooning limit. Detailed spectral analysis of the turbulence data is presented in the various limits.

  15. The Simulation Intranet Architecture

    SciTech Connect

    Holmes, V.P.; Linebarger, J.M.; Miller, D.J.; Vandewart, R.L.

    1998-12-02

    The Simdarion Infranet (S1) is a term which is being used to dcscribc one element of a multidisciplinary distributed and distance computing initiative known as DisCom2 at Sandia National Laboratory (http ct al. 1998). The Simulation Intranet is an architecture for satisfying Sandia's long term goal of providing an end- to-end set of scrviccs for high fidelity full physics simu- lations in a high performance, distributed, and distance computing environment. The Intranet Architecture group was formed to apply current distributed object technologies to this problcm. For the hardware architec- tures and software models involved with the current simulation process, a CORBA-based architecture is best suited to meet Sandia's needs. This paper presents the initial desi-a and implementation of this Intranct based on a three-tier Network Computing Architecture(NCA). The major parts of the architecture include: the Web Cli- ent, the Business Objects, and Data Persistence.

  16. The programmable ECG simulator.

    PubMed

    Caner, Candan; Engin, Mehmet; Engin, Erkan Zeki

    2008-08-01

    This paper reports the design and development of Digital Signal Controller (DSPIC)-based ECG simulator intended to use in testing, calibration and maintenance of electrocardiographic equipment, and to support biomedical engineering students' education. It generates all 12 healthy ECG derivation signals having a profile that varies with heart rate, amplitude, and different noise contamination in a manner which reflects true in vivo conditions. The heart rate can be set at the range of 30 to 120 beats/minute in four steps. The noise and power line interference effects can be set at the range of 0 to 20 dB in three steps. Since standard commercially available electronic components were used to construct the prototype simulator, the proposed design was also relatively inexpensive to produce.

  17. PEBBLES Mechanics Simulation Speedup

    SciTech Connect

    Joshua J. Cogliati; Abderrafi M. Ougouag

    2010-05-01

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. These simulations involve hundreds of thousands of pebbles and involve determining the entire core motion as pebbles are recirculated. Single processor algorithms for this are insufficient since they would take decades to centuries of wall-clock time. This paper describes the process of parallelizing and speeding up the PEBBLES pebble mechanics simulation code. Both shared memory programming with the Open Multi-Processing API and distributed memory programming with the Message Passing Interface API are used in simultaneously in this process. A new shared memory lock-less linear time collision detection algorithm is described. This method allows faster detection of pebbles in contact than generic methods. These combine to make full recirculations on AVR sized reactors possible in months of wall clock time.

  18. Simulators for Safer Shipping

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Each year one ship out of every five afloat collides with another vessel, rams a dock, or runs a ground. CAORF (Computer Aided Operations Research Facility), designed and built by Sperry Rand Corporation, incorporates technology developed in a wide variety of aerospace simulation and technical training programs. CAORF can be set up to duplicate the exact handling qualities of any vessel under various conditions of wind, tide and current. Currently a dozen different ships can be "plugged in." Bridge instrumentation is typical of modern shipboard equipment including radar, internal and external c.ommunications and new collision avoidance systems. From repetitive operation of simulated ships, MarAd is building a valuable data base for improving marine safety.

  19. Simulation of robot manipulators

    SciTech Connect

    Kress, R.L.; Babcock, S.M.; Bills, K.C.; Kwon, D.S.; Schoenwald, D.A.

    1995-03-01

    This paper describes Oak Ridge National Laboratory`s development of an environment for the simulation of robotic manipulators. Simulation includes the modeling of kinematics, dynamics, sensors, actuators, control systems, operators, and environments. Models will be used for manipulator design, proposal evaluation, control system design and analysis, graphical preview of proposed motions, safety system development, and training. Of particular interest is the development of models for robotic manipulators having at least one flexible link. As a first application, models have been developed for the Pacific Northwest Laboratories` Flexible Beam Testbed which is a one-Degree-Of-Freedom, flexible arm with a hydraulic base actuator. Initial results show good agreement between model and experiment.

  20. Simulation of Hyperspectral Images

    NASA Technical Reports Server (NTRS)

    Richsmeier, Steven C.; Singer-Berk, Alexander; Bernstein, Lawrence S.

    2004-01-01

    A software package generates simulated hyperspectral imagery for use in validating algorithms that generate estimates of Earth-surface spectral reflectance from hyperspectral images acquired by airborne and spaceborne instruments. This software is based on a direct simulation Monte Carlo approach for modeling three-dimensional atmospheric radiative transport, as well as reflections from surfaces characterized by spatially inhomogeneous bidirectional reflectance distribution functions. In this approach, "ground truth" is accurately known through input specification of surface and atmospheric properties, and it is practical to consider wide variations of these properties. The software can treat both land and ocean surfaces, as well as the effects of finite clouds with surface shadowing. The spectral/spatial data cubes computed by use of this software can serve both as a substitute for, and a supplement to, field validation data.

  1. Polydispersity and EXAFS simulations

    NASA Astrophysics Data System (ADS)

    Cammelli, S.; Lützenkirchen-Hecht, D.; Degueldre, C.; Bertsch, J.; Frahm, R.

    2009-11-01

    EXAFS is an important experimental technique for determining the local atomic structure of nanoclusters embedded in a bulk material. In practical cases, nanocluster samples do not contain homogeneous clusters of just one size, and the average cluster size is strongly influenced by the specific distribution of cluster sizes. Combinations of different cluster sizes might provide very similar results; this issue is called polydispersity. The goal of this study is to understand if there are any principal limitations for EXAFS studies related to polydispersity. Here a new approach based on EXAFS simulations followed by linear combination (LC) on EXAFS spectra is presented. The simulations were performed on pure Cu and binary Cu-Fe clusters. The main result of this study concerns the proof that polydispersity does not affect XAFS studies on nano-clusters within a size of up to 140 atoms.

  2. Maps and (no) Simulations

    NASA Astrophysics Data System (ADS)

    Forest, Etienne

    As the title suggests, I examine the role of maps in accelerator theory, conveniently leaving simulation out of the picture for lack of time and space. This is really a primer on the map-based "Courant Snyder" theory as independently proposed by Dragt's group (author included) and Turchetti's group at Bologna. Quite obviously it is viewed here from the author's own perspective and prejudices.

  3. Pershing II Simulation Studies

    DTIC Science & Technology

    1982-07-01

    Institute of Technology Engineering Experiment Station Atlanta, GA 30332 PREPARED FOR Systems Simulation and Development Directorate US Army Missile...PROGRAM ELEMENT, PROJECT, TASK AREA & WORK UNIT NUMBERS Georgia Institute of Technology Engineering Experiment Station Atlanta. Georgia 30332 11...of Technology , under Contract No. DAAHOI-81-D-AO03, Delivery Order No. 38, for the U. S. Army Missile Command. The contract technical monitor was M. H

  4. Universal Transparent Simulator (UNITRANS).

    DTIC Science & Technology

    1980-11-01

    Introduction .. ............. .......... . 2-1 2.2. General Concept ....... .................. .. 2-1 2.3. Linear Predictive Coding ( LPC ) -- Its Rudimentary...signal is then decoded back to physical voice by using t <. LPC synthesizing filter and then used as an input to the devices for testing. The result...predictive coding ( LPC ) technique (a full description on LPC will be introduced in the next section.) To simulate an individual successfully, the

  5. Radiation in Particle Simulations

    SciTech Connect

    More, R; Graziani, F; Glosli, J; Surh, M

    2010-11-19

    Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of megabars to thousands of gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known. The second method expands the electromagnetic field in normal modes (planewaves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion. The third method is a hybrid molecular dynamics/Monte Carlo (MD/MC) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions. The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc. This approach is inspired by the virial expansion method of equilibrium statistical mechanics. Using a combination of these methods we believe it is possible to do atomic-scale particle simulations of

  6. Online Simulation and Control

    DTIC Science & Technology

    2005-10-01

    Architecture 4.1.2. Web Services Client The Web Services Client uses the Liferay Portal to provide access to the modeling and simulation environment via...the web using a web browser. Liferay is an open source portal and is designed to be application server independent 1 . Liferay will work on...WebSphere. Liferay will also work on many operating systems such as BSD, Linux, Solaris, Mac OS X, and Windows. Our portal uses the JBoss/Tomcat

  7. Simulated Craters on Venus

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    The thick atmosphere of Venus prevents all but the largest impactors from cratering the surface. The number of small craters on Venus provides an interesting, and statistically significant test of models for the disruption and deceleration of impacting bodies. Here we compare Monte Carlo simulated crater distributions to the observed crater distribution on Venus. The simulation assumes: (1) a power law mass distribution for impactors of the form N(sub cum) alpha m (exp-b) where b=0.8; (2) isotropic incidence angles; (3) velocity at the top of the atmosphere of 20 kilometers per second (more realistic velocity distributions are also considered); (4) Schmidt-Housen crater scaling, modified such that only the normal component of the impact velocity contributes to cratering, and using crater slumping as parameterized (5) and modern populations (60% carbonaceous, 40% stone, 3% iron) and fluxes of asteroids. We use our previously developed model for the disruption and deceleration of large bodies striking thick planetary atmospheres to calculate the impact velocity at the surface as a function of impactor mass, incident velocity, and incident angle. We use a drag coefficient c(sub d) =1; other parameters are as described in Chyba et al. We set a low velocity cutoff of 500 meters per second on crater-forming impacts. Venus's craters are nicely matched by the simulated craters produced by 700 million years of striking asteroids. Shown for comparison are the simulated craters produced by incident comets over the same period, where for comets we have assumed b=0.7 and a flux at 10(exp 14) g 30% that of asteroids. Systematic uncertainties in crater scaling and crater slumping may make the surface age uncertain by a factor of two.

  8. Simulator Sickness Research Summary

    DTIC Science & Technology

    2007-07-01

    male drivers” (Hein, p. 610). 8.2 Age Walt Disney World’s “Mission: Space” thrill ride left some older riders gulping, “Houston, we have a problem...from physical aging may also be a contributing factor to this phenomenon, since those with more flight hours naturally tend to fall into older age...for determining the particular pattern of discomfort produced by a given simulator. All scores have as their lowest level a natural zero (no

  9. Simulations: The dark side

    NASA Astrophysics Data System (ADS)

    Frenkel, D.

    2013-01-01

    This paper discusses the Monte Carlo and Molecular Dynamics methods. Both methods are, in principle, simple. However, simple does not mean risk-free. In the literature, many of the pitfalls in the field are mentioned, but usually as a footnote --and these footnotes are scattered over many papers. The present paper focuses on the "dark side" of simulation: it is one big footnote. I should stress that "dark", in this context, has no negative moral implication. It just means: under-exposed.

  10. Simulating "Mars on Earth"

    NASA Technical Reports Server (NTRS)

    Clancey, William J.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    By now, everyone who's heard of the Haughton-Mars Project knows that we travel to Devon Island to learn how people will live and work on Mars. But how do we learn about Mars operations from what happens in the Arctic? We must document our experience--traverses, life in the hab, instrument deployment, communications, and so on. Then we must analyze and formally model what happens. In short, while most scientists are studying the crater, other scientists must be studying the expedition itself. That's what I have done in the past four field seasons. I study field science, both as it naturally occurs at Haughton (unconstrained by a "Mars Sam") and as a constrained experiment using the Flashline Mars Arctic Research Station. During the second week of July 2001, I lived and worked in the hab as part of the Phase 2 crew of six. Besides participating in all activities, I took many photographs and time lapse video. The result of my work will be a computer simulation of how we lived and worked in the hab. It won't be a model of particular people or even my own phase per se, but a pastiche that demonstrates (a proof of concept) that we have appropriate tools for simulating the layout of the hab and daily routines followed by the group and individual scientists. Activities-how people spend their time-are the focus of my observations for building such a simulation model.

  11. Space robot simulator vehicle

    NASA Technical Reports Server (NTRS)

    Cannon, R. H., Jr.; Alexander, H.

    1985-01-01

    A Space Robot Simulator Vehicle (SRSV) was constructed to model a free-flying robot capable of doing construction, manipulation and repair work in space. The SRSV is intended as a test bed for development of dynamic and static control methods for space robots. The vehicle is built around a two-foot-diameter air-cushion vehicle that carries batteries, power supplies, gas tanks, computer, reaction jets and radio equipment. It is fitted with one or two two-link manipulators, which may be of many possible designs, including flexible-link versions. Both the vehicle body and its first arm are nearly complete. Inverse dynamic control of the robot's manipulator has been successfully simulated using equations generated by the dynamic simulation package SDEXACT. In this mode, the position of the manipulator tip is controlled not by fixing the vehicle base through thruster operation, but by controlling the manipulator joint torques to achieve the desired tip motion, while allowing for the free motion of the vehicle base. One of the primary goals is to minimize use of the thrusters in favor of intelligent control of the manipulator. Ways to reduce the computational burden of control are described.

  12. Saltcake Dissolution Simulant Tests

    SciTech Connect

    Martino, C.J.

    2003-02-18

    Small-scale (15 to 50 mL) dissolution equilibrium tests were performed on surrogate waste representing typical saltcake at the Savannah River and Hanford Sites. The primary objectives of this study were to gain a better understanding of the solid-liquid equilibrium of simulated-waste saltcakes and chemistry of the dissolved salt solutions. These tests were performed in preparation for similar dissolution tests with actual-waste saltcakes. Two types of tests (single-wash and multiple-wash) were performed at two temperatures (25 degrees Celsius and 50 degrees Celsius) for each saltcake simulant. The compositions of the supernatant fluids are provided for both types of dissolution tests, and profiles of the elution of each salt component are provided for the multiple-wash tests. The conclusions from these tests follow: (1) For both salt waste surrogates, dissolution of the soluble components was achieved at less than a 2:1 mass ratio of inhibited water to saltcake during multiple-wash tests., (2) Dissolution of the Hanford S-112 simulant resulted in a relatively large weight percentage of residual insoluble material (4.2 wt. percent), which was identified as a mixture of Al(OH)3 phases (bayerite and gibbsite)., and (3) The profiles for the relative elution of anions from saltcake during dissolution exhibit distinctions that are dependent upon the dissolution temperature and the initial saltcake composition.

  13. YARNsim: Simulating Hadoop YARN

    SciTech Connect

    Liu, Ning; Yang, Xi; Sun, Xian-He; Jenkins, John; Ross, Robert

    2015-01-01

    Despite the popularity of the Apache Hadoop system, its success has been limited by issues such as single points of failure, centralized job/task management, and lack of support for programming models other than MapReduce. The next generation of Hadoop, Apache Hadoop YARN, is designed to address these issues. In this paper, we propose YARNsim, a simulation system for Hadoop YARN. YARNsim is based on parallel discrete event simulation and provides protocol-level accuracy in simulating key components of YARN. YARNsim provides a virtual platform on which system architects can evaluate the design and implementation of Hadoop YARN systems. Also, application developers can tune job performance and understand the tradeoffs between different configurations, and Hadoop YARN system vendors can evaluate system efficiency under limited budgets. To demonstrate the validity of YARNsim, we use it to model two real systems and compare the experimental results from YARNsim and the real systems. The experiments include standard Hadoop benchmarks, synthetic workloads, and a bioinformatics application. The results show that the error rate is within 10% for the majority of test cases. The experiments prove that YARNsim can provide what-if analysis for system designers in a timely manner and at minimal cost compared with testing and evaluating on a real system.

  14. Exploration Supply Chain Simulation

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Exploration Supply Chain Simulation project was chartered by the NASA Exploration Systems Mission Directorate to develop a software tool, with proper data, to quantitatively analyze supply chains for future program planning. This tool is a discrete-event simulation that uses the basic supply chain concepts of planning, sourcing, making, delivering, and returning. This supply chain perspective is combined with other discrete or continuous simulation factors. Discrete resource events (such as launch or delivery reviews) are represented as organizational functional units. Continuous resources (such as civil service or contractor program functions) are defined as enabling functional units. Concepts of fixed and variable costs are included in the model to allow the discrete events to interact with cost calculations. The definition file is intrinsic to the model, but a blank start can be initiated at any time. The current definition file is an Orion Ares I crew launch vehicle. Parameters stretch from Kennedy Space Center across and into other program entities (Michaud Assembly Facility, Aliant Techsystems, Stennis Space Center, Johnson Space Center, etc.) though these will only gain detail as the file continues to evolve. The Orion Ares I file definition in the tool continues to evolve, and analysis from this tool is expected in 2008. This is the first application of such business-driven modeling to a NASA/government-- aerospace contractor endeavor.

  15. Large scale traffic simulations

    SciTech Connect

    Nagel, K.; Barrett, C.L. |; Rickert, M. |

    1997-04-01

    Large scale microscopic (i.e. vehicle-based) traffic simulations pose high demands on computational speed in at least two application areas: (i) real-time traffic forecasting, and (ii) long-term planning applications (where repeated {open_quotes}looping{close_quotes} between the microsimulation and the simulated planning of individual person`s behavior is necessary). As a rough number, a real-time simulation of an area such as Los Angeles (ca. 1 million travellers) will need a computational speed of much higher than 1 million {open_quotes}particle{close_quotes} (= vehicle) updates per second. This paper reviews how this problem is approached in different projects and how these approaches are dependent both on the specific questions and on the prospective user community. The approaches reach from highly parallel and vectorizable, single-bit implementations on parallel supercomputers for Statistical Physics questions, via more realistic implementations on coupled workstations, to more complicated driving dynamics implemented again on parallel supercomputers. 45 refs., 9 figs., 1 tab.

  16. Terminal Descent Sensor Simulation

    NASA Technical Reports Server (NTRS)

    Chen, Curtis W.

    2009-01-01

    Sulcata software simulates the operation of the Mars Science Laboratory (MSL) radar terminal descent sensor (TDS). The program models TDS radar antennas, RF hardware, and digital processing, as well as the physics of scattering from a coherent ground surface. This application is specific to this sensor and is flexible enough to handle end-to-end design validation. Sulcata is a high-fidelity simulation and is used for performance evaluation, anomaly resolution, and design validation. Within the trajectory frame, almost all internal vectors are represented in whatever coordinate system is used to represent platform position. The trajectory frame must be planet-fixed. The platform body frame is specified relative to arbitrary reference points relative to the platform (spacecraft or test vehicle). Its rotation is a function of time from the trajectory coordinate system specified via dynamics input (file for open loop, callback for closed loop). Orientation of the frame relative to the body is arbitrary, but constant over time. The TDS frame must have a constant rotation and translation from the platform body frame specified at run time. The DEM frame has an arbitrary, but time-constant, rotation and translation with respect to the simulation frame specified at run time. It has the same orientation as sigma0 frame, but is possibly translated. Surface sigma0 has the same arbitrary rotation and translation as DEM frame.

  17. SATCOM constellation power simulation

    SciTech Connect

    Capulli, J.; Badke, B.; Davis, G.

    1995-12-31

    Three basic variables directly impact the power and energy generated by the SATCOM satellite constellation and its individual Space Vehicles (SVs). They are (1) telecommunications traffic patterns, (2) network resource management controllables, and (3) system hardware and software performance. This power simulation has verified the robustness of the telecommunications architecture. It has validated the onboard resource allocation process from an SV and network level power and energy perspective. The analyses have led to development of operational procedures that prevent SV node outages, and maximize network telecommunication traffic capacity. The program objective is to optimize overall system operation, availability and quality of service. Achieving this goal requires a thorough understanding of the Electrical Power Subsystem and its interfaces. The EPS simulation model analyzes network level performance by evaluating requirement compliance in the expected operating environments. Specifically, the simulation tool evaluates different design approaches and network operational strategies from a power and energy perspective. As a result, optimal load management solutions will be implemented both on-board the SV and via ground station directed resource allocation strategies.

  18. Simulating rotational grazing management.

    PubMed

    Cros, M J; Duru, M; Garcia, F; Martin-Clouaire, R

    2001-09-01

    Dairy systems predominantly based on rotational grazing are notoriously hard to manage. In order to ensure profitability, this type of production requires quite good organisation, planning, and operating capability on the part of the farmer. A simulation-based decision support system, called SEPATOU, has been developed for this purpose. At the core of the decision support approach lies an explicit and rigorous modelling of the management strategy that underlies a dairy farmer's decision-making behaviour (real or hypothetical). The SEPATOU system is a discrete-event simulator that reproduces the day-to-day dynamics of the farmer's decision process and the response of the controlled biophysical system for which models of grass growth, animal consumption, and milk production are used. SEPATOU provides the means to evaluate and compare tentative strategies by simulating their application throughout the production season under different hypothetical weather conditions. The relative worth of a strategy can be assessed by analysing the effects on the biophysical system and their variability across the representative range of possible conditions that is considered. The activities to be managed concern the type and amount of conserved feed, where to fertilise and how much, the choice of fields to harvest, and most importantly, which field to graze next. Typically, SEPATOU is designed to be used by extension services and farming system scientists. It is implemented in C++ and is currently undergoing a validation process with the intended users.

  19. Software Geometry in Simulations

    NASA Astrophysics Data System (ADS)

    Alion, Tyler; Viren, Brett; Junk, Tom

    2015-04-01

    The Long Baseline Neutrino Experiment (LBNE) involves many detectors. The experiment's near detector (ND) facility, may ultimately involve several detectors. The far detector (FD) will be significantly larger than any other Liquid Argon (LAr) detector yet constructed; many prototype detectors are being constructed and studied to motivate a plethora of proposed FD designs. Whether it be a constructed prototype or a proposed ND/FD design, every design must be simulated and analyzed. This presents a considerable challenge to LBNE software experts; each detector geometry must be described to the simulation software in an efficient way which allows for multiple authors to easily collaborate. Furthermore, different geometry versions must be tracked throughout their use. We present a framework called General Geometry Description (GGD), written and developed by LBNE software collaborators for managing software to generate geometries. Though GGD is flexible enough to be used by any experiment working with detectors, we present it's first use in generating Geometry Description Markup Language (GDML) files to interface with LArSoft, a framework of detector simulations, event reconstruction, and data analyses written for all LAr technology users at Fermilab. Brett is the other of the framework discussed here, the General Geometry Description (GGD).

  20. Simulation Data as Data Streams

    SciTech Connect

    Abdulla, G; Arrighi, W; Critchlow, T

    2003-11-18

    Computational or scientific simulations are increasingly being applied to solve a variety of scientific problems. Domains such as astrophysics, engineering, chemistry, biology, and environmental studies are benefiting from this important capability. Simulations, however, produce enormous amounts of data that need to be analyzed and understood. In this overview paper, we describe scientific simulation data, its characteristics, and the way scientists generate and use the data. We then compare and contrast simulation data to data streams. Finally, we describe our approach to analyzing simulation data, present the AQSim (Ad-hoc Queries for Simulation data) system, and discuss some of the challenges that result from handling this kind of data.

  1. Astronaut John Young in Command Module Simulator during Apollo Simulation

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Astronaut John W. Young, command module pilot, inside the Command Module Simulator in bldg 5 during an Apollo Simulation. Astronauts Thomas P. Stafford, commander and Eugene A. Cernan, lunar module pilot are out of the view.

  2. Three astronauts inside Command Module Simulator during Apollo Simulation

    NASA Technical Reports Server (NTRS)

    1968-01-01

    Three astronauts inside the Command Module Simulator in bldg 5 during an Apollo Simulation. Left to right are Astronauts Thomas P. Stafford, commander; John W. Young, command module pilot; and Eugene A. Cernan, lunar module pilot.

  3. GRMHD and GRPIC Simulations

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Watson, M.; Fuerst, S.; Wu, K.; Hardee, P.; Fishman, G. J.

    2007-01-01

    We have developed a new three-dimensional general relativistic magnetohydrodynamic (GRMHD) code by using a conservative, high-resolution shock-capturing scheme. The numerical fluxes are calculated using the HLL approximate Riemann solver scheme. The flux-interpolated constrained transport scheme is used to maintain a divergence-free magnetic field. We have performed various 1-dimensional test problems in both special and general relativity by using several reconstruction methods and found that the new 3D GRMHD code shows substantial improvements over our previous code. The simulation results show the jet formations from a geometrically thin accretion disk near a nonrotating and a rotating black hole. We will discuss the jet properties depended on the rotation of a black hole and the magnetic field configuration including issues for future research. A General Relativistic Particle-in-Cell Code (GRPIC) has been developed using the Kerr-Schild metric. The code includes kinetic effects, and is in accordance with GRMHD code. Since the gravitational force acting on particles is extreme near black holes, there are some difficulties in numerically describing these processes. The preliminary code consists of an accretion disk and free-falling corona. Results indicate that particles are ejected from the black hole. These results are consistent with other GRMHD simulations. The GRPIC simulation results will be presented, along with some remarks and future improvements. The emission is calculated from relativistic flows in black hole systems using a fully general relativistic radiative transfer formulation, with flow structures obtained by GRMHD simulations considering thermal free-free emission and thermal synchrotron emission. Bright filament-like features protrude (visually) from the accretion disk surface, which are enhancements of synchrotron emission where the magnetic field roughly aligns with the line-of-sight in the co-moving frame. The features move back and forth as

  4. Economics of simulation task force

    NASA Astrophysics Data System (ADS)

    Gordon, Steven C.

    2001-09-01

    It is both logical and appropriate for decision-makers to ask for ways to judge the value of simulation. Often, the request is even more pointed than just wanting a report on the value of simulation, and specifics on the economics of simulation are requested. Clearly, undertaking to answer questions about the economics of simulation will be critical to building an understanding of how to spend future marginal National Defense dollars. As an example, one can evaluate the economics of simulation where it supports our ability to develop, build, and test new weapon systems. Here, historically derived returns on investment, cost avoidance, cycle time reductions, and lifecycle cost savings have been documented and warrant further investigation. However, there is a larger area of use for simulation where judging its value must go beyond economics. Simulation, in most uses, has a value (or benefit or impact) beyond cost savings, and most efforts to understand the economics of simulation really intend to include the more general topic of the value of simulation. The broader question of the value of simulation will be tackled because simulation must prove its worth. If it is adequately funded and intelligently used, simulation will save valuable national resources and improve readiness. A task force of volunteers is now looking at the economics (benefits, value, impact) of simulation, and this paper seeks to provide an overview of the state of understanding of this topic and solicit volunteers to join this task force effort.

  5. Simulation Framework for Teaching in Modeling and Simulation Areas

    ERIC Educational Resources Information Center

    De Giusti, Marisa Raquel; Lira, Ariel Jorge; Villarreal, Gonzalo Lujan

    2008-01-01

    Simulation is the process of executing a model that describes a system with enough detail; this model has its entities, an internal state, some input and output variables and a list of processes bound to these variables. Teaching a simulation language such as general purpose simulation system (GPSS) is always a challenge, because of the way it…

  6. Molecular Simulations in Astrobiology

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Wilson, Michael A.; Schweighofer, Karl; Chipot, Christophe; New, Michael H.; Vincenzi, Donald L. (Technical Monitor)

    2001-01-01

    One of the main goals of astrobiology is to understand the origin of cellular life. In the absence of any record of the earliest ancestors of contemporary cells, protocells, the most direct way to test our understanding of their characteristics is to construct laboratory models of protocells. Such efforts, currently underway in the NASA Astrobiology Program, are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures and developing designs of molecules that are capable of performing protocellular functions. Many of these functions, such as importing nutrients, capturing and storing energy, and responding to changes in the environment, are carried out by proteins bound to membranes. We use computer simulations to address the following, questions about these proteins: (1) How do small proteins (peptides) organize themselves into ordered structures at water-membrane interfaces and insert into membranes? (2) How do peptides aggregate to form membrane-spannin(y structures (e.g., channels)? (3) By what mechanisms do such aggregates perform their functions? The simulations are performed using the molecular dynamics (MD) method. In this method, Newton's equations of motion for each atom in the system are solved iteratively. At each time step, the forces exerted on each atom by the remaining atoms are evaluated by dividing them into two parts. Short-range forces are calculated directly in real space while long-range forces are evaluated in reciprocal space, usually using a particle-mesh algorithm which is of order O(NlnN). Currently, a time step of 2 femtoseconds is typically used, thereby making studies of problems occurring on multi-nanosecond time scales (10(exp 6) - 10(exp 8) time steps) accessible. To address a broader range of problems, simulations need to be extended by three orders of magnitude. Such an extension requires both algorithmic improvements and codes scalable to a large number of parallel

  7. Simulator for heterogeneous dataflow architectures

    NASA Technical Reports Server (NTRS)

    Malekpour, Mahyar R.

    1993-01-01

    A new simulator is developed to simulate the execution of an algorithm graph in accordance with the Algorithm to Architecture Mapping Model (ATAMM) rules. ATAMM is a Petri Net model which describes the periodic execution of large-grained, data-independent dataflow graphs and which provides predictable steady state time-optimized performance. This simulator extends the ATAMM simulation capability from a heterogenous set of resources, or functional units, to a more general heterogenous architecture. Simulation test cases show that the simulator accurately executes the ATAMM rules for both a heterogenous architecture and a homogenous architecture, which is the special case for only one processor type. The simulator forms one tool in an ATAMM Integrated Environment which contains other tools for graph entry, graph modification for performance optimization, and playback of simulations for analysis.

  8. Rocket-Booster Towing Simulation

    NASA Technical Reports Server (NTRS)

    Trovillion, T. A.

    1985-01-01

    Report describes computer simulation of motion of solid-rocket ship. Listing of simulation program in FORTRAN. Mathematical techniques useful in such other maritime applications as buoy or ship design.

  9. Simulator for heterogeneous dataflow architectures

    NASA Astrophysics Data System (ADS)

    Malekpour, Mahyar R.

    1993-09-01

    A new simulator is developed to simulate the execution of an algorithm graph in accordance with the Algorithm to Architecture Mapping Model (ATAMM) rules. ATAMM is a Petri Net model which describes the periodic execution of large-grained, data-independent dataflow graphs and which provides predictable steady state time-optimized performance. This simulator extends the ATAMM simulation capability from a heterogenous set of resources, or functional units, to a more general heterogenous architecture. Simulation test cases show that the simulator accurately executes the ATAMM rules for both a heterogenous architecture and a homogenous architecture, which is the special case for only one processor type. The simulator forms one tool in an ATAMM Integrated Environment which contains other tools for graph entry, graph modification for performance optimization, and playback of simulations for analysis.

  10. Computer Simulation of Colliding Galaxies

    NASA Video Gallery

    Simulation of the formation of the galaxy known as "The Mice." The simulation depicts the merger of two spiral galaxies, pausing and rotating at the stage resembling the Hubble Space Telescope Adva...

  11. Look-ahead Dynamic Simulation

    SciTech Connect

    2015-10-20

    Look-ahead dynamic simulation software system incorporates the high performance parallel computing technologies, significantly reduces the solution time for each transient simulation case, and brings the dynamic simulation analysis into on-line applications to enable more transparency for better reliability and asset utilization. It takes the snapshot of the current power grid status, functions in parallel computing the system dynamic simulation, and outputs the transient response of the power system in real time.

  12. Situational simulations in interactive video

    SciTech Connect

    Smith, L.J.

    1991-07-01

    The Westinghouse Hanford Company Advanced Training Technologies section is using situational simulations in several Interactive Video training courses. Two applications of situational simulations will be discussed. In the first, used in the Hanford General Employee Training course, the student evaluates employee's actions in simulations of possible workplace situations. In the second, used in the Criticality Safety course, students must follow well-defined procedures to complete tasks. Design and incorporation of situational simulations will be discussed. 3 refs.

  13. Simulation in Training Workshop 2012

    DTIC Science & Technology

    2013-06-01

    to obtain more evidence regarding the cost-effectiveness of simulation and for the defence client to adopt more rigorous processes when acquiring...rigorous processes when acquiring a simulation capability, including better definition of training requirements and simulation specifications and...Dr Susannah Whitney (LOD) Use of Simulation in Individual versus Collective Training Dr Greg McLean ( AOD ) Exercise Black Skies 12: Evaluation of

  14. An Autonomous Platform Simulator (APS)

    DTIC Science & Technology

    1989-06-01

    communications between vehicle sim- ulators, sufficient data is needed to display the platform on a remote simulator as well as model its movement. Information ...window manager interface, FOGM modeling , and the overall program structure. 2. The Firing Platform Simulator The Firing Platform Simulator was a class...brakes, and steering. 3. Vehicle Motion Modeling Realistically simulating the response of vehicles to controls, such as throttle and steering, and to

  15. Is high fidelity human patient (mannequin) simulation, simulation of learning?

    PubMed

    McGarry, Denise; Cashin, Andrew; Fowler, Cathrine

    2014-08-01

    This paper explores the application of evaluation of high fidelity human patient (mannequin) simulation emerging in nursing education. The ramifications for use in mental health nursing are examined. A question is posed: Is high fidelity human patient (mannequin) simulation limited to being a "simulation of learning"? Explicit research that traces learning outcomes from mannequin, to clinical practice and hence consumer outcomes, is absent in mental health. Piecing together research from psychology addressing cognitive load theory and considering the capacity for learners to imitate desired behaviour without experiencing deep learning, the possibility is real that simulation of learning is the outcome of high fidelity human patient (mannequin) simulation applications to mental health nursing.

  16. Redesigned Human Metabolic Simulator

    NASA Technical Reports Server (NTRS)

    Duffield, Bruce; Jeng, Frank; Lange, Kevin

    2008-01-01

    A design has been formulated for a proposed improved version of an apparatus that simulates atmospheric effects of human respiration by introducing controlled amounts of carbon dioxide, water vapor, and heat into the air. Denoted a human metabolic simulator (HMS), the apparatus is used for testing life-support equipment when human test subjects are not available. The prior version of the HMS, to be replaced, was designed to simulate the respiratory effects of as many as four persons. It exploits the catalytic combustion of methyl acetate, for which the respiratory quotient (the molar ratio of carbon dioxide produced to oxygen consumed) is very close to the human respiratory quotient of about 0.86. The design of the improved HMS provides for simulation of the respiratory effects of as many as eight persons at various levels of activity. The design would also increase safety by eliminating the use of combustion. The improved HMS (see figure) would include a computer that would exert overall control. The computer would calculate the required amounts of oxygen removal, carbon dioxide addition, water addition, and heat addition by use of empirical equations for metabolic profiles of respiration and heat. A blower would circulate air between the HMS and a chamber containing a life-support system to be tested. With the help of feedback from a mass flowmeter, the blower speed would be adjusted to regulate the rate of flow according to the number of persons to be simulated and to a temperature-regulation requirement (the air temperature would indirectly depend on the rate of flow, among other parameters). Oxygen would be removed from the circulating air by means of a commercially available molecular sieve configured as an oxygen concentrator. Oxygen, argon, and trace amounts of nitrogen would pass through a bed in the molecular sieve while carbon dioxide, the majority of nitrogen, and other trace gases would be trapped by the bed and subsequently returned to the chamber. If

  17. Visual Elements in Flight Simulation

    DTIC Science & Technology

    1975-07-01

    control. In consequence, current efforts tc create appropriate visual simulations run the gamut from efforts toward almost complete replication of the...create appropriate visual simulations run the gamut from efforts to create appropriate visual simulations run the gamut from efforts toward almost

  18. Helicopter simulation: Making it work

    NASA Technical Reports Server (NTRS)

    Payne, Barry

    1992-01-01

    The opportunities for improved training and checking by using helicopter simulators are greater than they are for airplane pilot training. Simulators permit the safe creation of training environments that are conducive to the development of pilot decision-making, situational awareness, and cockpit management. This paper defines specific attributes required in a simulator to meet a typical helicopter operator's training and checking objectives.

  19. New Directions in Maintenance Simulation.

    ERIC Educational Resources Information Center

    Miller, Gary G.

    A two-phase effort was conducted to design and evaluate a maintenance simulator which incorporated state-of-the-art information in simulation and instructional technology. The particular equipment selected to be simulated was the 6883 Convert/Flight Controls Test Station. Phase I included a generalized block diagram of the computer-trainer, the…

  20. Visualization for starlight navigation simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Yang, Zhaowei; Zhang, Yi; Yu, Hong; Du, Huijie; Gao, Yang; Lei, Jie

    2014-12-01

    The star sensor simulation system is uesed to test the star sensor performance on the ground,which is designed for star identification and spacecraft attitude determnation of the spacecraft. The computer star scene based on the astronomical star chat is generated for hardware-in-the-loop simulation of the star sensor simulation system using by openGL.

  1. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  2. Simulation-based surgical education.

    PubMed

    Evgeniou, Evgenios; Loizou, Peter

    2013-09-01

    The reduction in time for training at the workplace has created a challenge for the traditional apprenticeship model of training. Simulation offers the opportunity for repeated practice in a safe and controlled environment, focusing on trainees and tailored to their needs. Recent technological advances have led to the development of various simulators, which have already been introduced in surgical training. The complexity and fidelity of the available simulators vary, therefore depending on our recourses we should select the appropriate simulator for the task or skill we want to teach. Educational theory informs us about the importance of context in professional learning. Simulation should therefore recreate the clinical environment and its complexity. Contemporary approaches to simulation have introduced novel ideas for teaching teamwork, communication skills and professionalism. In order for simulation-based training to be successful, simulators have to be validated appropriately and integrated in a training curriculum. Within a surgical curriculum, trainees should have protected time for simulation-based training, under appropriate supervision. Simulation-based surgical education should allow the appropriate practice of technical skills without ignoring the clinical context and must strike an adequate balance between the simulation environment and simulators.

  3. Plasma theory and simulation research

    SciTech Connect

    Birdsall, C.K.

    1989-01-01

    Our research group uses both theory and simulation as tools in order to increase the understanding of instabilities, heating, diffusion, transport and other phenomena in plasmas. We also work on the improvement of simulation, both theoretically and practically. Our focus has been more and more on the plasma edge (the sheath''), interactions with boundaries, leading to simulations of whole devices (someday a numerical tokamak).

  4. Bio-threat microparticle simulants

    DOEpatents

    Farquar, George Roy; Leif, Roald

    2014-09-16

    A bio-threat simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the bio-threat simulant.

  5. Bio-threat microparticle simulants

    DOEpatents

    Farquar, George Roy; Leif, Roald N

    2012-10-23

    A bio-threat simulant that includes a carrier and DNA encapsulated in the carrier. Also a method of making a simulant including the steps of providing a carrier and encapsulating DNA in the carrier to produce the bio-threat simulant.

  6. MSFC Skylab neutral buoyancy simulator

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The use of a neutral buoyancy simulator for developing extravehicular activity systems and for training astronauts in weightless activities is discussed. The construction of the facility and the operations are described. The types of tests and the training activities conducted in the simulator are reported. Photographs of the components of the simulator and actual training exercises are included.

  7. Probability Simulation in Middle School.

    ERIC Educational Resources Information Center

    Lappan, Glenda; Winter, M. J.

    1980-01-01

    Two simulations designed to teach probability to middle-school age pupils are presented. The first simulates the one-on-one foul shot simulation in basketball; the second deals with collecting a set of six cereal box prizes by buying boxes containing one toy each. (MP)

  8. Circuit simulation: some humbling thoughts

    SciTech Connect

    Wendt, Manfred; /Fermilab

    2006-01-01

    A short, very personal note on circuit simulation is presented. It does neither include theoretical background on circuit simulation, nor offers an overview of available software, but just gives some general remarks for a discussion on circuit simulator needs in context to the design and development of accelerator beam instrumentation circuits and systems.

  9. Epistemology of knowledge based simulation

    SciTech Connect

    Reddy, R.

    1987-04-01

    Combining artificial intelligence concepts, with traditional simulation methodologies yields a powerful design support tool known as knowledge based simulation. This approach turns a descriptive simulation tool into a prescriptive tool, one which recommends specific goals. Much work in the area of general goal processing and explanation of recommendations remains to be done.

  10. Coupling expert systems and simulation

    NASA Technical Reports Server (NTRS)

    Kawamura, K.; Beale, G.; Padalkar, S.; Rodriguez-Moscoso, J.; Hsieh, B. J.; Vinz, F.; Fernandez, K. R.

    1988-01-01

    A prototype coupled system called NESS (NASA Expert Simulation System) is described. NESS assists the user in running digital simulations of dynamic systems, interprets the output data to performance specifications, and recommends a suitable series compensator to be added to the simulation model.

  11. Binaural room simulation

    NASA Technical Reports Server (NTRS)

    Lehnert, H.; Blauert, Jens; Pompetzki, W.

    1991-01-01

    In every-day listening the auditory event perceived by a listener is determined not only by the sound signal that a sound emits but also by a variety of environmental parameters. These parameters are the position, orientation and directional characteristics of the sound source, the listener's position and orientation, the geometrical and acoustical properties of surfaces which affect the sound field and the sound propagation properties of the surrounding fluid. A complete set of these parameters can be called an Acoustic Environment. If the auditory event perceived by a listener is manipulated in such a way that the listener is shifted acoustically into a different acoustic environment without moving himself physically, a Virtual Acoustic Environment has been created. Here, we deal with a special technique to set up nearly arbitrary Virtual Acoustic Environments, the Binaural Room Simulation. The purpose of the Binaural Room Simulation is to compute the binaural impulse response related to a virtual acoustic environment taking into account all parameters mentioned above. One possible way to describe a Virtual Acoustic Environment is the concept of the virtual sound sources. Each of the virtual sources emits a certain signal which is correlated but not necessarily identical with the signal emitted by the direct sound source. If source and receiver are non moving, the acoustic environment becomes a linear time-invariant system. Then, the Binaural Impulse Response from the source to a listener' s eardrums contains all relevant auditory information related to the Virtual Acoustic Environment. Listening into the simulated environment can easily be achieved by convolving the Binaural Impulse Response with dry signals and representing the results via headphones.

  12. Radiation in Particle Simulations

    SciTech Connect

    More, R M; Graziani, F R; Glosli, J; Surh, M

    2009-06-15

    Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of Megabars to thousands of Gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present four methods that attempt a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The first method applies the Lienard-Weichert solution of Maxwell's equations for a classical particle whose motion is assumed to be known (section 3). The second method expands the electromagnetic field in normal modes (plane-waves in a box with periodic boundary-conditions) and solves the equation for wave amplitudes coupled to the particle motion (section 4). The third method is a hybrid MD/MC (molecular dynamics/Monte Carlo) method which calculates radiation emitted or absorbed by electron-ion pairs during close collisions (section 5). The fourth method is a generalization of the third method to include small clusters of particles emitting radiation during close encounters: one electron simultaneously hitting two ions, two electrons simultaneously hitting one ion, etc.(section 6). This approach is inspired by the Virial expansion method of equilibrium statistical mechanics.

  13. Plasma Simulation Program

    SciTech Connect

    Greenwald, Martin

    2011-10-04

    Many others in the fusion energy and advanced scientific computing communities participated in the development of this plan. The core planning team is grateful for their important contributions. This summary is meant as a quick overview the Fusion Simulation Program's (FSP's) purpose and intentions. There are several additional documents referenced within this one and all are supplemental or flow down from this Program Plan. The overall science goal of the DOE Office of Fusion Energy Sciences (FES) Fusion Simulation Program (FSP) is to develop predictive simulation capability for magnetically confined fusion plasmas at an unprecedented level of integration and fidelity. This will directly support and enable effective U.S. participation in International Thermonuclear Experimental Reactor (ITER) research and the overall mission of delivering practical fusion energy. The FSP will address a rich set of scientific issues together with experimental programs, producing validated integrated physics results. This is very well aligned with the mission of the ITER Organization to coordinate with its members the integrated modeling and control of fusion plasmas, including benchmarking and validation activities. [1]. Initial FSP research will focus on two critical Integrated Science Application (ISA) areas: ISA1, the plasma edge; and ISA2, whole device modeling (WDM) including disruption avoidance. The first of these problems involves the narrow plasma boundary layer and its complex interactions with the plasma core and the surrounding material wall. The second requires development of a computationally tractable, but comprehensive model that describes all equilibrium and dynamic processes at a sufficient level of detail to provide useful prediction of the temporal evolution of fusion plasma experiments. The initial driver for the whole device model will be prediction and avoidance of discharge-terminating disruptions, especially at high performance, which are a critical

  14. Simulation of surface processes

    PubMed Central

    Jónsson, Hannes

    2011-01-01

    Computer simulations of surface processes can reveal unexpected insight regarding atomic-scale structure and transitions. Here, the strengths and weaknesses of some commonly used approaches are reviewed as well as promising avenues for improvements. The electronic degrees of freedom are usually described by gradient-dependent functionals within Kohn–Sham density functional theory. Although this level of theory has been remarkably successful in numerous studies, several important problems require a more accurate theoretical description. It is important to develop new tools to make it possible to study, for example, localized defect states and band gaps in large and complex systems. Preliminary results presented here show that orbital density-dependent functionals provide a promising avenue, but they require the development of new numerical methods and substantial changes to codes designed for Kohn–Sham density functional theory. The nuclear degrees of freedom can, in most cases, be described by the classical equations of motion; however, they still pose a significant challenge, because the time scale of interesting transitions, which typically involve substantial free energy barriers, is much longer than the time scale of vibrations—often 10 orders of magnitude. Therefore, simulation of diffusion, structural annealing, and chemical reactions cannot be achieved with direct simulation of the classical dynamics. Alternative approaches are needed. One such approach is transition state theory as implemented in the adaptive kinetic Monte Carlo algorithm, which, thus far, has relied on the harmonic approximation but could be extended and made applicable to systems with rougher energy landscape and transitions through quantum mechanical tunneling. PMID:21199939

  15. Simulation System Fidelity Assessment at the Vertical Motion Simulator

    NASA Technical Reports Server (NTRS)

    Beard, Steven D.; Reardon, Scott E.; Tobias, Eric L.; Aponso, Bimal L.

    2013-01-01

    Fidelity is a word that is often used but rarely understood when talking about groundbased simulation. Assessing the cueing fidelity of a ground based flight simulator requires a comparison to actual flight data either directly or indirectly. Two experiments were conducted at the Vertical Motion Simulator using the GenHel UH-60A Black Hawk helicopter math model that was directly compared to flight data. Prior to the experiment the simulator s motion and visual system frequency responses were measured, the aircraft math model was adjusted to account for the simulator motion system delays, and the motion system gains and washouts were tuned for the individual tasks. The tuned motion system fidelity was then assessed against the modified Sinacori criteria. The first experiments showed similar handling qualities ratings (HQRs) to actual flight for a bob-up and sidestep maneuvers. The second experiment showed equivalent HQRs between flight and simulation for the ADS33 slalom maneuver for the two pilot participants. The ADS33 vertical maneuver HQRs were mixed with one pilot rating the flight and simulation the same while the second pilot rated the simulation worse. In addition to recording HQRs on the second experiment, an experimental Simulation Fidelity Rating (SFR) scale developed by the University of Liverpool was tested for applicability to engineering simulators. A discussion of the SFR scale for use on the Vertical Motion Simulator is included in this paper.

  16. Auditory perceptual simulation: Simulating speech rates or accents?

    PubMed

    Zhou, Peiyun; Christianson, Kiel

    2016-07-01

    When readers engage in Auditory Perceptual Simulation (APS) during silent reading, they mentally simulate characteristics of voices attributed to a particular speaker or a character depicted in the text. Previous research found that auditory perceptual simulation of a faster native English speaker during silent reading led to shorter reading times that auditory perceptual simulation of a slower non-native English speaker. Yet, it was uncertain whether this difference was triggered by the different speech rates of the speakers, or by the difficulty of simulating an unfamiliar accent. The current study investigates this question by comparing faster Indian-English speech and slower American-English speech in the auditory perceptual simulation paradigm. Analyses of reading times of individual words and the full sentence reveal that the auditory perceptual simulation effect again modulated reading rate, and auditory perceptual simulation of the faster Indian-English speech led to faster reading rates compared to auditory perceptual simulation of the slower American-English speech. The comparison between this experiment and the data from Zhou and Christianson (2016) demonstrate further that the "speakers'" speech rates, rather than the difficulty of simulating a non-native accent, is the primary mechanism underlying auditory perceptual simulation effects.

  17. Modern Physics Simulations

    NASA Astrophysics Data System (ADS)

    Brandt, Douglas; Hiller, John R.; Moloney, Michael J.

    1995-10-01

    The Consortium for Upper Level Physics Software (CUPS) has developed a comprehensive series of Nine Book/Software packages that Wiley will publish in FY `95 and `96. CUPS is an international group of 27 physicists, all with extensive backgrounds in the research, teaching, and development of instructional software. The project is being supported by the National Science Foundation (PHY-9014548), and it has received other support from the IBM Corp., Apple Computer Corp., and George Mason University. The Simulations being developed are: Astrophysics, Classical Mechanics, Electricity & Magnetism, Modern Physics, Nuclear and Particle Physics, Quantum Mechanics, Solid State, Thermal and Statistical, and Wave and Optics.

  18. Computationally efficient multibody simulations

    NASA Technical Reports Server (NTRS)

    Ramakrishnan, Jayant; Kumar, Manoj

    1994-01-01

    Computationally efficient approaches to the solution of the dynamics of multibody systems are presented in this work. The computational efficiency is derived from both the algorithmic and implementational standpoint. Order(n) approaches provide a new formulation of the equations of motion eliminating the assembly and numerical inversion of a system mass matrix as required by conventional algorithms. Computational efficiency is also gained in the implementation phase by the symbolic processing and parallel implementation of these equations. Comparison of this algorithm with existing multibody simulation programs illustrates the increased computational efficiency.

  19. Simulating motivated cognition

    NASA Technical Reports Server (NTRS)

    Gevarter, William B.

    1991-01-01

    A research effort to develop a sophisticated computer model of human behavior is described. A computer framework of motivated cognition was developed. Motivated cognition focuses on the motivations or affects that provide the context and drive in human cognition and decision making. A conceptual architecture of the human decision-making approach from the perspective of information processing in the human brain is developed in diagrammatic form. A preliminary version of such a diagram is presented. This architecture is then used as a vehicle for successfully constructing a computer program simulation Dweck and Leggett's findings that relate how an individual's implicit theories orient them toward particular goals, with resultant cognitions, affects, and behavior.

  20. Fusion Simulation Program

    SciTech Connect

    Project Staff

    2012-02-29

    Under this project, General Atomics (GA) was tasked to develop the experimental validation plans for two high priority ISAs, Boundary and Pedestal and Whole Device Modeling in collaboration with the theory, simulation and experimental communities. The following sections have been incorporated into the final FSP Program Plan (www.pppl.gov/fsp), which was delivered to the US Department of Energy (DOE). Additional deliverables by GA include guidance for validation, development of metrics to evaluate success and procedures for collaboration with experiments. These are also part of the final report.

  1. SEALING SIMULATED LEAKS

    SciTech Connect

    Michael A. Romano

    2004-09-01

    This report details the testing equipment, procedures and results performed under Task 7.2 Sealing Simulated Leaks. In terms of our ability to seal leaks identified in the technical topical report, Analysis of Current Field Data, we were 100% successful. In regards to maintaining seal integrity after pigging operations we achieved varying degrees of success. Internal Corrosion defects proved to be the most resistant to the effects of pigging while External Corrosion proved to be the least resistant. Overall, with limitations, pressure activated sealant technology would be a viable option under the right circumstances.

  2. Artificial intelligence and simulation

    SciTech Connect

    Holmes, W.M.

    1985-01-01

    The research and development of AI are discussed. Papers are presented on an expert system for chemical process control, an ocean surveillance information fusion expert system, a distributed intelligence system and aircraft pilotage, a procedure for speeding innovation by transferring scientific knowledge more quickly, and syntax programming, expert systems, and real-time fault diagnosis. Consideration is given to an expert system for modeling NASA flight control room usage, simulating aphasia, a method for single neuron recognition of letters, numbers, faces, and certain types of concepts, integrating AI and control system approach, testing an expert system for manufacturing, and the human memory.

  3. Fading channel simulator

    SciTech Connect

    Argo, P.E.; Fitzgerald, T.J.

    1991-12-31

    This invention relates to high frequency (HF) radio signal propagation through fading channels and, more particularly, to simulation of fading channels in order to characterize HF radio system performance in transmitting and receiving signals through such fading channels. Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

  4. Laparoscopic simulation interface

    DOEpatents

    Rosenberg, Louis B.

    2006-04-04

    A method and apparatus for providing high bandwidth and low noise mechanical input and output for computer systems. A gimbal mechanism provides two revolute degrees of freedom to an object about two axes of rotation. A linear axis member is coupled to the gimbal mechanism at the intersection of the two axes of rotation. The linear axis member is capable of being translated along a third axis to provide a third degree of freedom. The user object is coupled to the linear axis member and is thus translatable along the third axis so that the object can be moved along all three degrees of freedom. Transducers associated with the provided degrees of freedom include sensors and actuators and provide an electromechanical interface between the object and a digital processing system. Capstan drive mechanisms transmit forces between the transducers and the object. The linear axis member can also be rotated about its lengthwise axis to provide a fourth degree of freedom, and, optionally, a floating gimbal mechanism is coupled to the linear axis member to provide fifth and sixth degrees of freedom to an object. Transducer sensors are associated with the fourth, fifth, and sixth degrees of freedom. The interface is well suited for simulations of medical procedures and simulations in which an object such as a stylus or a joystick is moved and manipulated by the user.

  5. Zero Power Reactor Simulation

    SciTech Connect

    2010-01-01

    Ever wanted to see a nuclear reactor core in action? Here's a detailed simulation of the Zero Power Reactor experiment, run by Argonne's unique "UNIC" code. Here, we use VisIt to visualize a numerical model of the ZPR-6 Assembly 6a experiment simulated using the Argonne UNIC code. 0:00-0:06: The fuel and other plates are dropped into an example drawer, and the drawer is inserted into the matrix tube. 0:06-0:21: The two matrix halves are brought together to make a critical (self-sustaining) assembly. 0:21-0:35: The fission power is revealed to be centralized in the thin, enriched Uranium plates. 0:35-0:53: Returning to our example drawer, we show the detailed local plate powers and their relation to the drawer composition. 0:53-1:11: Our model shows that each plate can have widely-varying local changes in the space and energy neutron densities. Read more at http://www.anl.gov/Media_Center/News/2010/news100121.html

  6. Reactor Simulator Testing

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.; Webster, Kenny L.; Pearson, Boise J..

    2013-01-01

    As part of the Nuclear Systems Office Fission Surface Power Technology Demonstration Unit (TDU) project, a reactor simulator test loop (RxSim) was design & built to perform integrated testing of the TDU components. In particular, the objectives of RxSim testing was to verify the operation of the core simulator, the instrumentation and control system, and the ground support gas and vacuum test equipment. In addition, it was decided to include a thermal test of a cold trap purification design and a pump performance test at pump voltages up to 150 V since the targeted mass flow rate of 1.75 kg/s was not obtained in the RxSim at the originally constrained voltage of 120 V. This paper summarizes RxSim testing. The gas and vacuum ground support test equipment performed effectively in NaK fill, loop pressurization, and NaK drain operations. The instrumentation and control system effectively controlled loop temperature and flow rates or pump voltage to targeted settings. The cold trap design was able to obtain the targeted cold temperature of 480 K. An outlet temperature of 636 K was obtained which was lower than the predicted 750 K but 156 K higher than the cold temperature indicating the design provided some heat regeneration. The annular linear induction pump (ALIP) tested was able to produce a maximum flow rate of 1.53 kg/s at 800 K when operated at 150 V and 53 Hz.

  7. Reactor Simulator Testing Overview

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.

    2013-01-01

    Test Objectives Summary: a) Verify operation of the core simulator, the instrumentation & control system, and the ground support gas and vacuum test equipment. b) Examine cooling & heat regeneration performance of the cold trap purification. c) Test the ALIP pump at voltages beyond 120V to see if the targeted mass flow rate of 1.75 kg/s can be obtained in the RxSim. Testing Highlights: a) Gas and vacuum ground support test equipment performed effectively for operations (NaK fill, loop pressurization, and NaK drain). b) Instrumentation & Control system effectively controlled loop temperature and flow rates or pump voltage to targeted settings and ramped within prescribed constraints. It effectively interacted with reactor simulator control model and defaulted back to temperature control mode if the transient fluctuations didn't dampen. c) Cold trap design was able to obtain the targeted cold temperature of 480 K. An outlet temperature of 636 K was obtained which was lower than the predicted 750 K but 156 K higher than the minimum temperature indicating the design provided some heat regeneration. d) ALIP produce a maximum flow rate of 1.53 kg/s at 800 K when operated at 150 V and 53 Hz.

  8. Confidence in Numerical Simulations

    SciTech Connect

    Hemez, Francois M.

    2015-02-23

    This PowerPoint presentation offers a high-level discussion of uncertainty, confidence and credibility in scientific Modeling and Simulation (M&S). It begins by briefly evoking M&S trends in computational physics and engineering. The first thrust of the discussion is to emphasize that the role of M&S in decision-making is either to support reasoning by similarity or to “forecast,” that is, make predictions about the future or extrapolate to settings or environments that cannot be tested experimentally. The second thrust is to explain that M&S-aided decision-making is an exercise in uncertainty management. The three broad classes of uncertainty in computational physics and engineering are variability and randomness, numerical uncertainty and model-form uncertainty. The last part of the discussion addresses how scientists “think.” This thought process parallels the scientific method where by a hypothesis is formulated, often accompanied by simplifying assumptions, then, physical experiments and numerical simulations are performed to confirm or reject the hypothesis. “Confidence” derives, not just from the levels of training and experience of analysts, but also from the rigor with which these assessments are performed, documented and peer-reviewed.

  9. An automation simulation testbed

    NASA Technical Reports Server (NTRS)

    Cook, George E.; Sztipanovits, Janos; Biegl, Csaba; Karsai, Gabor; Springfield, James F.; Mutammara, Atheel

    1988-01-01

    The work being done in porting ROBOSIM (a graphical simulation system developed jointly by NASA-MSFC and Vanderbilt University) to the HP350SRX graphics workstation is described. New additional ROBOSIM features, like collision detection and new kinematics simulation methods are also discussed. Based on the experiences of the work on ROBOSIM, a new graphics structural modeling environment is suggested which is intended to be a part of a new knowledge-based multiple aspect modeling testbed. The knowledge-based modeling methodologies and tools already available are described. Three case studies in the area of Space Station automation are also reported. First a geometrical structural model of the station is presented. This model was developed using the ROBOSIM package. Next the possible application areas of an integrated modeling environment in the testing of different Space Station operations are discussed. One of these possible application areas is the modeling of the Environmental Control and Life Support System (ECLSS), which is one of the most complex subsystems of the station. Using the multiple aspect modeling methodology, a fault propagation model of this system is being built and is described.

  10. Simple stochastic simulation.

    PubMed

    Schilstra, Maria J; Martin, Stephen R

    2009-01-01

    Stochastic simulations may be used to describe changes with time of a reaction system in a way that explicitly accounts for the fact that molecules show a significant degree of randomness in their dynamic behavior. The stochastic approach is almost invariably used when small numbers of molecules or molecular assemblies are involved because this randomness leads to significant deviations from the predictions of the conventional deterministic (or continuous) approach to the simulation of biochemical kinetics. Advances in computational methods over the three decades that have elapsed since the publication of Daniel Gillespie's seminal paper in 1977 (J. Phys. Chem. 81, 2340-2361) have allowed researchers to produce highly sophisticated models of complex biological systems. However, these models are frequently highly specific for the particular application and their description often involves mathematical treatments inaccessible to the nonspecialist. For anyone completely new to the field to apply such techniques in their own work might seem at first sight to be a rather intimidating prospect. However, the fundamental principles underlying the approach are in essence rather simple, and the aim of this article is to provide an entry point to the field for a newcomer. It focuses mainly on these general principles, both kinetic and computational, which tend to be not particularly well covered in specialist literature, and shows that interesting information may even be obtained using very simple operations in a conventional spreadsheet.

  11. Modern Physics Simulations

    NASA Astrophysics Data System (ADS)

    Lopez, Jorge; Correa, Jose

    1999-10-01

    Due to the lack of laboratories for introductory modern physics classes, Dr. Jorge A. Lopez and Mr. Jose Ricardo Correa from the UTEP Physics Department work in the development of computer simulations of important modern physics experiments for the aforementioned physics classes. The presentation will inform the audience about this resource in the instruction of introductory modern physics as well as the success it has had. Introductory modern physics classes expose students to radically new concepts that defy common sense. As if this was not hard enough, students encounter a lack of hands-on activities due to the lack of lab equipment for their modern physics class. This is to be understood since most of the experiments cannot be performed in the conditions university laboratories provide and at the undergraduate level organization. Therefore, much time and effort have been devoted to the development of computer simulations of key modern physics experiments. These virtual experiments are a great alternative that will alleviate the limitations physics professors face when teaching introductory modern physics courses in addition to enchance student understanding.

  12. Vertical motion simulator familiarization guide

    NASA Technical Reports Server (NTRS)

    Danek, George L.

    1993-01-01

    The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms.

  13. PUREX irradiated fuel recovery simulation

    SciTech Connect

    Jaquish, W.R.

    1994-09-01

    This paper discusses the application of IGRIP (Interactive Graphical Robot Instruction Program) to assist environmental remediation efforts at the Department of Energy PUREX Plant at the Hanford Site. An IGRIP simulation was developed to plan, review, and verify proposed remediation activities. This simulation was designed to satisfy a number of unique purposes that each placed specific constraints and requirements on the design and implementation of the simulation. These purposes and their influence on the design of the simulation are presented. A discussion of several control code architectures for mechanical system simulations, including their advantages and limitations, is also presented.

  14. Simulations of the WUVS instrument

    NASA Astrophysics Data System (ADS)

    Marcos-Arenal, Pablo; Gómez de Castro, Ana I.; Perea Abarca, Belén.; Sachkov, Mikhail

    2016-07-01

    The performance of the WUVS (WSO-UV Spectrographs) can be evaluated through simulations of the expected observations. Here we discuss the implementation details and the noise models applied in the simulation software tool developed to carry on these simulations. The WUVS Simulator has been implemented as a further development of the PLATO Simulator, adapting it to the WUVS specific characteristics. It is designed to generate synthetic time-series of images by including models of all important noise sources. The expected overall noise budget of the output images is evaluated as a function of different sets of input parameters describing the instrument properties.

  15. Transportation Anslysis Simulation System

    SciTech Connect

    2004-08-23

    TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the region’s individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at the level of households and individual travelers. Trips a planned to satisfy the population’s activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not account

  16. [New simulation technologies in neurosurgery].

    PubMed

    Byvaltsev, V A; Belykh, E G; Konovalov, N A

    2016-01-01

    The article presents a literature review on the current state of simulation technologies in neurosurgery, a brief description of the basic technology and the classification of simulation models, and examples of simulation models and skills simulators used in neurosurgery. Basic models for the development of physical skills, the spectrum of available computer virtual simulators, and their main characteristics are described. It would be instructive to include microneurosurgical training and a cadaver course of neurosurgical approaches in neurosurgery training programs and to extend the use of three-dimensional imaging. Technologies for producing three-dimensional anatomical models and patient-specific computer simulators as well as improvement of tactile feedback systems and display quality of virtual models are promising areas. Continued professional education necessitates further research for assessing the validity and practical use of simulators and physical models.

  17. A Flexible Simulation Architecture for Pandemic Influenza Simulation

    PubMed Central

    Eriksson, Henrik; Timpka, Toomas; Ekberg, Joakim; Spreco, Armin; Dahlström, Örjan; Strömgren, Magnus; Holm, Einar

    2015-01-01

    Simulation is an important resource for studying the dynamics of pandemic influenza and predicting the potential impact of interventions. However, there are several challenges for the design of such simulator architectures. Specifically, it is difficult to develop simulators that combine flexibility with run-time performance. This tradeoff is problematic in the pandemic-response setting because it makes it challenging to extend and adapt simulators for ongoing situations where rapid results are indispensable. Simulation architectures based on aspect-oriented programming can model specific concerns of the simulator and can allow developers to rapidly extend the simulator in new ways without sacrificing run-time performance. It is possible to use such aspects in conjunction with separate simulation models, which define community, disease, and intervention properties. The implication of this research for pandemic response is that aspects can add a novel layer of flexibility to simulation environments, which enables modelers to extend the simulator run-time component to new requirements that go beyond the original modeling framework. PMID:26958187

  18. X-15 simulator

    NASA Technical Reports Server (NTRS)

    1961-01-01

    This photo shows the X-15 flight simulator located at the NASA Flight Research Center, Edwards, California, in the 1960s. One of the major advances in aircraft development, pilot training, mission planning, and research flight activities in the 1950s and 1960s was the use of simulators. For the X-15, a computer was programmed with the flight characteristics of the aircraft. Before actually flying a mission, a research pilot could discover many potential problems with the aircraft or the mission while still on the ground by 'flying' the simulator. The problem could then be analyzed by engineers and a solution found. This did much to improve safety. The X-15 simulator was very limited compared to those available in the 21st century. The video display was simple, while the computer was analog rather than digital (although it became hybrid in 1964 with the addition of a digital computer for the X-15A-2; this generated the nonlinear aerodynamic coefficients for the modified No. 2 aircraft). The nonlinear aerodynamic function generators used in the X-15 simulator had hundreds of fuses, amplifiers, and potentiometers without any surge protection. After the simulator was started on a Monday morning, it would be noon before it had warmed up and stabilized. The electronics for the X-15 simulator took up many large consoles. The X-15 was a rocket-powered aircraft. The original three aircraft were about 50 ft long with a wingspan of 22 ft. The modified #2 aircraft (X-15A-2 was longer.) They were a missile-shaped vehicles with unusual wedge-shaped vertical tails, thin stubby wings, and unique side fairings that extended along the side of the fuselage. The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch. The XLR-99 rocket engine, manufactured by Thiokol Chemical Corp., was pilot controlled and was rated at 57,000 lb of thrust, although there are indications that it actually achieved up to 60,000 lb. North American Aviation built three X-15 aircraft for

  19. Chip level simulation of fault tolerant computers

    NASA Technical Reports Server (NTRS)

    Armstrong, J. R.

    1983-01-01

    Chip level modeling techniques, functional fault simulation, simulation software development, a more efficient, high level version of GSP, and a parallel architecture for functional simulation are discussed.

  20. Virtual Flow Simulator

    SciTech Connect

    Calderer, Antoni; Yang, Xiaolei; Angelidis, Dionysios; Khosronejad, Ali; Le, Trung; Kang, Seokkoo; Gilmanov, Anvar; Ge, Liang; Borazjani, Iman

    2015-10-05

    Virtual Flow Simulator (VFS) is a state-of-the-art computational fluid mechanics (CFD) package that is capable of simulating multi-physics/multi-phase flows with the most advanced turbulence models (RANS, LES) over complex terrains. The flow solver is based on the Curvilinear Immersed Boundary (CURVIB) method to handle geometrically complex and moving domains. Different modules of the VFS package can provide different simulation capabilities for specific applications ranging from the fluid-structure interaction (FSI) of solid and deformable bodies, the two-phase free surface flow solver based on the level set method for ocean waves, sediment transport models in rivers and the large-scale models of wind farms based on actuator lines and surfaces. All numerical features of VFS package have been validated with known analytical and experimental data as reported in the related journal articles. VFS package is suitable for a broad range of engineering applications within different industries. VFS has been used in different projects with applications in wind and hydrokinetic energy, offshore and near-shore ocean studies, cardiovascular and biological flows, and natural streams and river morphodynamics. Over the last decade, the development of VFS has been supported and assisted with the help of various United States companies and federal agencies that are listed in the sponsor lists. In this version, VFS-Wind contains all the necessary modeling tools for wind energy applications, including land-based and offshore wind farms. VFS is highly scalable to run on either desktop computers or high performance clusters (up to 16,000 CPUs). This released version comes with a detailed user’s manual and a set of case studies designed to facilitate the learning of the various aspects of the code in a comprehensive manner. The included documentation and support material has been elaborated in a collaboration effort with Sandia National Labs under the contract DE-EE0005482. The VFS

  1. Physics-Based Simulator for NEO Exploration Analysis & Simulation

    NASA Technical Reports Server (NTRS)

    Balaram, J.; Cameron, J.; Jain, A.; Kline, H.; Lim, C.; Mazhar, H.; Myint, S.; Nayar, H.; Patton, R.; Pomerantz, M.; Quadrelli, M.; Shakkotai, P.; Tso, K.

    2011-01-01

    As part of the Space Exploration Analysis and Simulation (SEAS) task, the National Aeronautics and Space Administration (NASA) is using physics-based simulations at NASA's Jet Propulsion Laboratory (JPL) to explore potential surface and near-surface mission operations at Near Earth Objects (NEOs). The simulator is under development at JPL and can be used to provide detailed analysis of various surface and near-surface NEO robotic and human exploration concepts. In this paper we describe the SEAS simulator and provide examples of recent mission systems and operations concepts investigated using the simulation. We also present related analysis work and tools developed for both the SEAS task as well as general modeling, analysis and simulation capabilites for asteroid/small-body objects.

  2. Mars ultraviolet simulation facility.

    PubMed

    Zill, L P; Mack, R; DeVincenzi, D L

    1979-12-01

    A facility was established for long-duration ultraviolet (UV) radiation exposure of natural and synthetic materials in order to test hypotheses concerning Martian soil chemistry observed by the Viking Mars landers. The system utilized a 2500 watt xenon lamp as the radiation source, with the beam passing through a heat-dissipating water filter before impinging upon an exposure chamber containing the samples to be irradiated. The chamber was designed to allow for continuous tumbling of the samples, maintenance of temperatures below 0 degrees C during exposure, and monitoring of beam intensity. The facility also provided for sample preparation under a variety of atmospheric conditions, in addition to the Mars nominal. As many as 33 sealed sample ampules have been irradiated in a single exposure. Over 100 samples have been irradiated for approximately 100 to 700 h. The facility has performed well in providing continuous UV irradiation of multiple samples for long periods of time under simulated Mars atmospheric and thermal conditions.

  3. Memory Circuit Fault Simulator

    NASA Technical Reports Server (NTRS)

    Sheldon, Douglas J.; McClure, Tucker

    2013-01-01

    Spacecraft are known to experience significant memory part-related failures and problems, both pre- and postlaunch. These memory parts include both static and dynamic memories (SRAM and DRAM). These failures manifest themselves in a variety of ways, such as pattern-sensitive failures, timingsensitive failures, etc. Because of the mission critical nature memory devices play in spacecraft architecture and operation, understanding their failure modes is vital to successful mission operation. To support this need, a generic simulation tool that can model different data patterns in conjunction with variable write and read conditions was developed. This tool is a mathematical and graphical way to embed pattern, electrical, and physical information to perform what-if analysis as part of a root cause failure analysis effort.

  4. Phobos Mobility Simulation

    NASA Technical Reports Server (NTRS)

    Bielski, Paul

    2015-01-01

    Phobos, the larger of Mars' moons, provides a potential staging location for human exploration of the Martian surface. Its low gravity (about 1/200th of Earth) and lack of atmosphere makes it an attractive destination before a more complex human landing on Mars is attempted. While easier to approach and depart than Mars itself, Phobos provides unique challenges to visiting crews. It is irregularly shaped, so its local gravitational field does not always point straight down with respect to the visible horizon. It is very close to Mars and tidally locked, so the Martian gravity gradient and applied acceleration greatly affect the perceived surface gravity direction and magnitude. This simulation allows the assessment of unique mobility approaches on the surface of Phobos, including hopping in particular.

  5. PV Hourly Simulation Tool

    SciTech Connect

    Dean, Jesse; Metzger, Ian

    2010-12-31

    This software requires inputs of simple general building characteristics and usage information to calculate the energy and cost benefits of solar PV. This tool conducts and complex hourly simulation of solar PV based primarily on the area available on the rooftop. It uses a simplified efficiency calculation method and real panel characteristics. It includes a detailed rate structure to account for time-of-use rates, on-peak and off-peak pricing, and multiple rate seasons. This tool includes the option for advanced system design inputs if they are known. This tool calculates energy savings, demand reduction, cost savings, incentives and building life cycle costs including: simple payback, discounted payback, net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.

  6. Simulations of Fluvial Landscapes

    NASA Astrophysics Data System (ADS)

    Cattan, D.; Birnir, B.

    2013-12-01

    The Smith-Bretherton-Birnir (SBB) model for fluvial landsurfaces consists of a pair of partial differential equations, one governing water flow and one governing the sediment flow. Numerical solutions of these equations have been shown to provide realistic models in the evolution of fluvial landscapes. Further analysis of these equations shows that they possess scaling laws (Hack's Law) that are known to exist in nature. However, the simulations are highly dependent on the numerical methods used; with implicit methods exhibiting the correct scaling laws, but the explicit methods fail to do so. These equations, and the resulting models, help to bridge the gap between the deterministic and the stochastic theories of landscape evolution. Slight modifications of the SBB equations make the results of the model more realistic. By modifying the sediment flow equation, the model obtains more pronounced meandering rivers. Typical landsurface with rivers.

  7. Computer simulation of microstructure

    NASA Astrophysics Data System (ADS)

    Xu, Ping; Morris, J. W.

    1992-11-01

    The microstructure that results from a martensitic transformation is largely determined by the elastic strain that develops as martensite particles grow and interact. To study the development of microstructure, it is useful to have computer simulation models that mimic the process. One such model is a finite-element model in which the transforming body is divided into elementary cells that transform when it is energetically favorable to do so. Using the linear elastic theory, the elastic energy of an arbitrary distribution of transformed cells can be calculated, and the elastic strain field can be monitored as the transformation proceeds. In the present article, a model of this type is developed and evaluated by testing its ability to generate the preferred configurations of isolated martensite particles, which can be predicted analytically from the linear elastic theory. Both two- and three-dimensional versions of the model are used. The computer model is in good agreement with analytic theory when the latter predicts single-variant martensite particles. The three-dimensional model also generates twinned martensite in reason- able agreement with the analytic predictions when the fractions of the two variants in the particle are near 0.5. It is less successful in reproducing twinned martensites when one variant is dom- inant; however, in this case, it does produce unusual morphologies, such as “butterfly mar- tensite,” that have been observed experimentally. Neither the analytic theory nor the computer simulation predicts twinned martensites in the two-dimensional transformations considered here, revealing an inherent limitation of studies that are restricted to two dimensions.

  8. Mars Ice Age, Simulated

    NASA Technical Reports Server (NTRS)

    2003-01-01

    December 17, 2003

    This simulated view shows Mars as it might have appeared during the height of a possible ice age in geologically recent time.

    Of all Solar System planets, Mars has the climate most like that of Earth. Both are sensitive to small changes in orbit and tilt. During a period about 2.1 million to 400,000 years ago, increased tilt of Mars' rotational axis caused increased solar heating at the poles. A new study using observations from NASA's Mars Global Surveyor and Mars Odyssey orbiters concludes that this polar warming caused mobilization of water vapor and dust into the atmosphere, and buildup of a surface deposit of ice and dust down to about 30 degrees latitude in both hemispheres. That is the equivalent of the southern Unites States or Saudi Arabia on Earth. Mars has been in an interglacial period characterized by less axial tilt for about the last 300,000 years. The ice-rich surface deposit has been degrading in the latitude zone of 30 degrees to 60 degrees as water-ice returns to the poles.

    In this illustration prepared for the December 18, 2003, cover of the journal Nature, the simulated surface deposit is superposed on a topography map based on altitude measurements by Global Surveyor and images from NASA's Viking orbiters of the 1970s.

    Mars Global Surveyor and Mars Odyssey are managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, for the NASA Office of Space Science, Washington.

  9. Mesoscopic simulations of recrystallization

    SciTech Connect

    Holm, E.A.; Rollett, A.D.; Srolovitz, D.J.

    1995-08-01

    The application of computer simulation to grain growth and recrystallization was strongly stimulated in the early 80s by the realization that Monte Carlo models could be applied to problems of grain structure evolution. By extension of the Ising model for domain modeling of magnetic domains to the Potts model (with generalized spin numbers) it was then possible to represent discretely grains (domains) by regions of similarly oriented sets of material (lattice) points. In parallel with this fascinating development, there also occured notable work on analytical models, especially by Abbruzzese and Bunge, which has been particularly useful for understanding the variation of texture (crystallographic preferred orientation) during grain growth processes. Geometric models of recrystallization, worked on most recently and productively by Nes et al., have been useful in connection with grain size prediction as a result of recrystallization. Also, mesh-based models have been developed to a high degree by Kawasaki, Fradkov and others, and, rather recently, by Humphreys to model not just grain growth but also the nucleation process in recrystallization. These models have the strength that they deal with the essential features of grains, i.e. the nodes, but have some limitations when second phases must be considered. These various approaches to modeling of recrystallization processes will be reviewed, with a special emphasis on practical approaches to implementing the Potts model. This model has been remarkably successful in modeling such diverse phenomena as dynamic recrystallization, secondary recrystallization (abnormal grain growth), particle-inhibited recrystallization, and grain structure evolution in soldering and welding. In summary, the application of mesoscopic simulation to the phenomenon of recrystallization has yielded much new insight into some longstanding deficiencies in our understanding.

  10. Reactor Simulator Testing

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.; Webster, Kenny L.; Pearson, Boise Jon

    2013-01-01

    As part of the Nuclear Systems Office Fission Surface Power Technology Demonstration Unit (TDU) project, a reactor simulator test loop (RxSim) was design & built to perform integrated testing of the TDU components. In particular, the objectives of RxSim testing was to verify the operation of the core simulator, the instrumentation and control system, and the ground support gas and vacuum test equipment. In addition, it was decided to include a thermal test of a cold trap purification design and a pump performance test at pump voltages up to 150 V since the targeted mass flow rate of 1.75 kg/s was not obtained in the RxSim at the originally constrained voltage of 120 V. This paper summarizes RxSim testing. The gas and vacuum ground support test equipment performed effectively in NaK fill, loop pressurization, and NaK drain operations. The instrumentation and control system effectively controlled loop temperature and flow rates or pump voltage to targeted settings. The cold trap design was able to obtain the targeted cold temperature of 480 K. An outlet temperature of 636 K was obtained which was lower than the predicted 750 K but 156 K higher than the cold temperature indicating the design provided some heat regeneration. The annular linear induction pump (ALIP) tested was able to produce a maximum flow rate of 1.53 kg/s at 800 K when operated at 150 V and 53 Hz. Keywords: fission, space power, nuclear, liquid metal, NaK.

  11. Unsteady Turbopump Flow Simulations

    NASA Technical Reports Server (NTRS)

    Centin, Kiris C.; Kwak, Dochan

    2001-01-01

    The objective of the current effort is two-fold: 1) to provide a computational framework for design and analysis of the entire fuel supply system of a liquid rocket engine; and 2) to provide high-fidelity unsteady turbopump flow analysis capability to support the design of pump sub-systems for advanced space transportation vehicle. Since the space launch systems in the near future are likely to involve liquid propulsion system, increasing the efficiency and reliability of the turbopump components is an important task. To date, computational tools for design/analysis of turbopump flow are based on relatively lower fidelity methods. Unsteady, three-dimensional viscous flow analysis tool involving stationary and rotational components for the entire turbopump assembly has not been available, at least, for real-world engineering applications. Present effort is an attempt to provide this capability so that developers of the vehicle will be able to extract such information as transient flow phenomena for start up, impact of non-uniform inflow, system vibration and impact on the structure. Those quantities are not readily available from simplified design tools. In this presentation, the progress being made toward complete turbo-pump simulation capability for a liquid rocket engine is reported. Space Shuttle Main Engine (SSME) turbo-pump is used as a test case for the performance evaluation of the hybrid MPI/Open-MP and MLP versions of the INS3D code. Relative motion of the grid system for rotor-stator interaction was obtained by employing overset grid techniques. Time-accuracy of the scheme has been evaluated by using simple test cases. Unsteady computations for SSME turbopump, which contains 106 zones with 34.5 Million grid points, are currently underway on Origin 2000 systems at NASA Ames Research Center. Results from these time-accurate simulations with moving boundary capability and the performance of the parallel versions of the code will be presented.

  12. Wind shear and turbulence simulation

    NASA Technical Reports Server (NTRS)

    Bowles, Roland L.

    1987-01-01

    The aviation community is increasing its reliance on flight simulators. This is true both in pilot training and in research and development. In moving research concepts through the development pipeline, there is a sequence of events which take place: analysis, ground based simulation, inflight simulation, and flight testing. Increasing fidelity as progress toward the flight testing arena is accompanied by increasing cost. The question that seems to be posed in relation to the meteorological aspects of flight simulation is, How much fidelity is enough and can it be quantified. As a part of the Langley Simulation Technology Program, there are three principal areas of focus, one being improved simulation of weather hazards. A close liaison with the JAWS project was established because of the Langley Simulation Technology interests regarding reliable simulation of severe convective weather phenomena and their impact on aviation systems. Simulation offers the only feasible approach for examining the utility of new technology and new procedures for coping with severe convective weather phenomena such as wind shear. These simulation concepts are discussed in detail.

  13. Simulation in surgery: a review.

    PubMed

    Tan, Shaun Shi Yan; Sarker, Sudip K

    2011-05-01

    The ability to acquire surgical skills requires consistent practice, and evidence suggests that many of these technical skills can be learnt away from the operating theatre. The aim of this review article is to discuss the importance of surgical simulation today and its various types, exploring the effectiveness of simulation in the clinical setting and its challenges for the future. Surgical simulation offers the opportunity for trainees to practise their surgical skills prior to entering the operating theatre, allowing detailed feedback and objective assessment of their performance. This enables better patient safety and standards of care. Surgical simulators can be divided into organic or inorganic simulators. Organic simulators, consisting of live animal and fresh human cadaver models, are considered to be of high-fidelity. Inorganic simulators comprise virtual reality simulators and synthetic bench models. Current evidence suggests that skills acquired through training with simulators, positively transfers to the clinical setting and improves operative outcome. The major challenge for the future revolves around understanding the value of this new technology and developing an educational curriculum that can incorporate surgical simulators.

  14. Communication Systems Simulation Laboratory (CSSL): Simulation Planning Guide

    NASA Technical Reports Server (NTRS)

    Schlesinger, Adam

    2012-01-01

    The simulation process, milestones and inputs are unknowns to first-time users of the CSSL. The Simulation Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their engineering personnel in simulation planning and execution. Material covered includes a roadmap of the simulation process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, facility interfaces, and inputs necessary to define scope, cost, and schedule are included as an appendix to the guide.

  15. Distributed simulation of network protocols

    NASA Technical Reports Server (NTRS)

    Paterra, Frank; Overstreet, C. Michael; Maly, Kurt J.

    1990-01-01

    Simulations of high speed network protocols are very CPU intensive operations requiring very long run times. Very high speed network protocols (Gigabit/sec rates) require longer simulation runs in order to reach a steady state, while at the same time requiring additional CPU processing for each unit of time because of the data rates for the traffic being simulated. As protocol development proceeds and simulations provide insights into any problems associated with the protocol, the simulation model often must be changed to generate additional or finer statistical performance information. Iterating on this process is very time consuming due to the required run times for the simulation models. The results of the efforts to distribute a high speed ring network protocol, Carrier Sensed Multiple Access/Ring Network (CSMA/RN), are presented.

  16. Stochastic simulation of transport phenomena

    SciTech Connect

    Wedgewood, L.E.; Geurts, K.R.

    1995-10-01

    In this paper, four examples are given to demonstrate how stochastic simulations can be used as a method to obtain numerical solutions to transport problems. The problems considered are two-dimensional heat conduction, mass diffusion with reaction, the start-up of Poiseuille flow, and Couette flow of a suspension of Hookean dumbbells. The first three examples are standard problems with well-known analytic solutions which can be used to verify the results of the stochastic simulation. The fourth example combines a Brownian dynamics simulation for Hookean dumbbells, a crude model of a dilute polymer suspension, and a stochastic simulation for the suspending, Newtonian fluid. These examples illustrate appropriate methods for handling source/sink terms and initial and boundary conditions. The stochastic simulation results compare well with the analytic solutions and other numerical solutions. The goal of this paper is to demonstrate the wide applicability of stochastic simulation as a numerical method for transport problems.

  17. The Shuttle Mission Simulator computer generated imagery

    NASA Technical Reports Server (NTRS)

    Henderson, T. H.

    1984-01-01

    Equipment available in the primary training facility for the Space Transportation System (STS) flight crews includes the Fixed Base Simulator, the Motion Base Simulator, the Spacelab Simulator, and the Guidance and Navigation Simulator. The Shuttle Mission Simulator (SMS) consists of the Fixed Base Simulator and the Motion Base Simulator. The SMS utilizes four visual Computer Generated Image (CGI) systems. The Motion Base Simulator has a forward crew station with six-degrees of freedom motion simulation. Operation of the Spacelab Simulator is planned for the spring of 1983. The Guidance and Navigation Simulator went into operation in 1982. Aspects of orbital visual simulation are discussed, taking into account the earth scene, payload simulation, the generation and display of 1079 stars, the simulation of sun glare, and Reaction Control System jet firing plumes. Attention is also given to landing site visual simulation, and night launch and landing simulation.

  18. Experiential Learning through Computer-Based Simulations.

    ERIC Educational Resources Information Center

    Maynes, Bill; And Others

    1992-01-01

    Describes experiential learning instructional model and simulation for student principals. Describes interactive laser videodisc simulation. Reports preliminary findings about student principal learning from simulation. Examines learning approaches by unsuccessful and successful students and learning levels of model learners. Simulation's success…

  19. HADES, A Radiographic Simulation Code

    SciTech Connect

    Aufderheide, M.B.; Slone, D.M.; Schach von Wittenau, A.E.

    2000-08-18

    We describe features of the HADES radiographic simulation code. We begin with a discussion of why it is useful to simulate transmission radiography. The capabilities of HADES are described, followed by an application of HADES to a dynamic experiment recently performed at the Los Alamos Neutron Science Center. We describe quantitative comparisons between experimental data and HADES simulations using a copper step wedge. We conclude with a short discussion of future work planned for HADES.

  20. Non-detonable explosive simulators

    DOEpatents

    Simpson, R.L.; Pruneda, C.O.

    1994-11-01

    A simulator which is chemically equivalent to an explosive, but is not detonable. The simulator has particular use in the training of explosives detecting dogs and calibrating sensitive analytical instruments. The explosive simulants may be fabricated by different techniques, a first involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and the second involves coating inert beads with thin layers of explosive molecules. 5 figs.

  1. Non-detonable explosive simulators

    DOEpatents

    Simpson, Randall L.; Pruneda, Cesar O.

    1994-01-01

    A simulator which is chemically equivalent to an explosive, but is not detonable. The simulator has particular use in the training of explosives detecting dogs and calibrating sensitive analytical instruments. The explosive simulants may be fabricated by different techniques, a first involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and the second involves coating inert beads with thin layers of explosive molecules.

  2. Manpower Analysis Using Discrete Simulation

    DTIC Science & Technology

    2015-12-01

    building using Discrete Event Simulation (DES) and experimentation using Design of Experiments (DOE). We derived five metamodels to identify the most...objectives were met. 14. SUBJECT TERMS manpower policy analysis, discrete event simulation, Simkit 15. NUMBER OF PAGES 85 16. PRICE CODE 17. SECURITY...using Discrete Event Simulation (DES) and experimentation using Design of Experiments (DOE). We derived five metamodels to identify the most

  3. Medical Simulation for Trauma Management.

    DTIC Science & Technology

    1997-10-01

    too slow to allow realistic deformation of a volumetric representation. Recently, Wiet et al. have presented an endoscopic sinus surgery simulator...simulator systems in recent years, including simulators for neuro- endoscopic surgery, interventional radiology, rigid bronchoscopy, and flexible...mentioned blue spill removal. Other circuits deal with glare, uneven or dirty blue backings, etc. Modern units from the Model V and up can independently

  4. Open cherry picker simulation results

    NASA Technical Reports Server (NTRS)

    Nathan, C. A.

    1982-01-01

    The simulation program associated with a key piece of support equipment to be used to service satellites directly from the Shuttle is assessed. The Open Cherry Picker (OCP) is a manned platform mounted at the end of the remote manipulator system (RMS) and is used to enhance extra vehicular activities (EVA). The results of simulations performed on the Grumman Large Amplitude Space Simulator (LASS) and at the JSC Water Immersion Facility are summarized.

  5. The promise of quantum simulation

    SciTech Connect

    Muller, Richard P.; Blume-Kohout, Robin

    2015-07-21

    In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH+ molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.

  6. The promise of quantum simulation

    DOE PAGES

    Muller, Richard P.; Blume-Kohout, Robin

    2015-07-21

    In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH+ molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.

  7. Parallel Power Grid Simulation Toolkit

    SciTech Connect

    Smith, Steve; Kelley, Brian; Banks, Lawrence; Top, Philip; Woodward, Carol

    2015-09-14

    ParGrid is a 'wrapper' that integrates a coupled Power Grid Simulation toolkit consisting of a library to manage the synchronization and communication of independent simulations. The included library code in ParGid, named FSKIT, is intended to support the coupling multiple continuous and discrete even parallel simulations. The code is designed using modern object oriented C++ methods utilizing C++11 and current Boost libraries to ensure compatibility with multiple operating systems and environments.

  8. Simulations of Polymer Translocation

    NASA Astrophysics Data System (ADS)

    Vocks, H.

    2008-07-01

    Transport of molecules across membranes is an essential mechanism for life processes. These molecules are often long, and the pores in the membranes are too narrow for the molecules to pass through as a single unit. In such circumstances, the molecules have to squeeze -- i.e., translocate -- themselves through the pores. DNA, RNA and proteins are such naturally occuring long molecules in a variety of biological processes. Understandably, the process of translocation has been an active topic of current research: not only because it is a cornerstone of many biological processes, but also due to its relevance for practical applications. Translocation is a complicated process in living organisms -- the presence of chaperone molecules, pH, chemical potential gradients, and assisting molecular motors strongly influence its dynamics. Consequently, the translocation process has been empirically studied in great variety in biological literature. Study of translocation as a biophysical process is more recent. Herein, the polymer is simplified to a sequentially connected string of N monomers as it passes through a narrow pore on a membrane. The quantities of interest are the typical time scale for the polymer to leave a confining cell (the ``escape of a polymer from a vesicle'' time scale), and the typical time scale the polymer spends in the pore (the ``dwell'' time scale) as a function of N and other parameters like membrane thickness, membrane adsorption, electrochemical potential gradient, etc. Our research is focused on computer simulations of translocation. Since our main interest is in the scaling properties, we use a highly simplified description of the translocation process. The polymer is described as a self-avoiding walk on a lattice, and its dynamics consists of single-monomer jumps from one lattice site to another neighboring one. Since we have a very efficient program to simulate such polymer dynamics, which we decribe in Chapter 2, we can perform long

  9. Hybrid Solar GHP Simulator

    SciTech Connect

    Yavuzturk, Cy; Chiasson, Andrew; Shonder, John

    2012-12-11

    This project provides an easy-to-use, menu-driven, software tool for designing hybrid solar-geothermal heat pump systems (GHP) for both heating- and cooling-dominated buildings. No such design tool currently exists. In heating-dominated buildings, the design approach takes advantage of glazed solar collectors to effectively balance the annual thermal loads on the ground with renewable solar energy. In cooling-dominated climates, the design approach takes advantage of relatively low-cost, unglazed solar collectors as the heat rejecting component. The primary benefit of hybrid GHPs is the reduced initial cost of the ground heat exchanger (GHX). Furthermore, solar thermal collectors can be used to balance the ground loads over the annual cycle, thus making the GHX fully sustainable; in heating-dominated buildings, the hybrid energy source (i.e., solar) is renewable, in contrast to a typical fossil fuel boiler or electric resistance as the hybrid component; in cooling-dominated buildings, use of unglazed solar collectors as a heat rejecter allows for passive heat rejection, in contrast to a cooling tower that consumes a significant amount of energy to operate, and hybrid GHPs can expand the market by allowing reduced GHX footprint in both heating- and cooling-dominated climates. The design tool allows for the straight-forward design of innovative GHP systems that currently pose a significant design challenge. The project lays the foundations for proper and reliable design of hybrid GHP systems, overcoming a series of difficult and cumbersome steps without the use of a system simulation approach, and without an automated optimization scheme. As new technologies and design concepts emerge, sophisticated design tools and methodologies must accompany them and be made usable for practitioners. Lack of reliable design tools results in reluctance of practitioners to implement more complex systems. A menu-driven software tool for the design of hybrid solar GHP systems is

  10. Thermoacoustic simulator for regenerative machines

    NASA Astrophysics Data System (ADS)

    Luo, E.; Wu, J.; Yang, J.; Xiao, J.

    2002-05-01

    Linear thermoacoustic theory is a powerful tool to understand the working mechanism of many regenerative machines. Based on the theory, the authors have developed a computer code "Thermoacoustic Simulator" for analyzing and designing different regenerative cryocoolers including String refrigerators, Stirling and G-M types of pulse tube refrigerators and G-M cryocoolers. Also, standing-wave and traveling-wave thermoacoustic machines can be simulated, too. This paper will present the philosophy of the "Thermoacoustic Simulator" and some demonstrations of simulation for different types of cryocoolers and thermoacoustic engines.

  11. Requirements definition by numerical simulation

    NASA Astrophysics Data System (ADS)

    Hickman, James J.; Kostas, Chris; Tsang, Kang T.

    1994-10-01

    We are investigating the issues involved in requirements definition for narcotics interdiction: how much of a particular signature is possible, how does this amount change for different conditions, and what is the temporal relationship in various scenarios. Our approach has been to simulate numerically the conditions that arise during vapor or particulate transport. The advantages of this approach are that (1) a broad range of scenarios can be rapidly and inexpensively analyzed by simulation, and (2) simulations can display quantities that are difficult or impossible to measure. The drawback of this approach is that simulations cannot include all of the phenomena present in a real measurement, and therefore the fidelity of the simulation results is always an issue. To address this limitation, we will ultimately combine the results of numerical simulations with measurements of physical parameters for inclusion in the simulation. In this paper, we discuss these issues and how they apply to the current problems in narcotics interdictions, especially cargo containers. We also show the results of 1D and 3D numerical simulations, and compare these results with analytical solutions. The results indicate that this approach is viable. We also present data from 3D simulations of vapor transport in a loaded cargo container and some of the issues present in this ongoing work.

  12. Thirty years of lithography simulation

    NASA Astrophysics Data System (ADS)

    Mack, Chris A.

    2005-05-01

    Thirty years ago Rick Dill and his team at IBM published the first account of lithography simulation - the accurate description of semiconductor optical lithography by mathematical equations. Since then, lithography simulation has grown dramatically in importance in four important areas: as a research tool, as a development tool, as a manufacturing tool, and as a learning tool. In this paper, the history of lithography simulations is traced from its roots to today"s indispensable tools for lithographic technology development. Along the way, an attempt will be made to define the true value of lithography simulation to the semiconductor industry.

  13. Medical simulation in anesthesiology training.

    PubMed

    Bressan, F; Buti, G; Boncinelli, S

    2007-01-01

    Simulators are more and more widely used in different scientific areas. Through very sophisticated and realistic simulations, they actually permit to teach and demonstrate theoretical or practical notions. Besides, they allow to evaluate a particular performance. In the latest years, the use of simulators has considerably developed in medicine. Anaesthetists have been the first to use and develop simulation. Having the possibility to deal with emergencies and getting accustomed to them without any real risk is an undeniable advantage. Even though the long-term effects due to a simulation session haven't been properly evaluated yet, it is important to bear in mind that simulators are being successfully used in an impressive number of centres in different parts of the world. The activities in the medical simulation centres deal to a certain extent with studying and teaching to manage critical events. This particular discipline, deriving from the aeronautic field, relies upon decision making and teamwork in order to manage the critical event most appropriately. Formative trainings, initially meant for anaesthetists and later on open to other medical categories as well, have been developed. Such courses aimed at establishing the proper interactions between different people with different tasks who are involved in the approach to an emergency rather than the management of the whole scenario. The main drawback of simulation is, however, the high costs required to set a simulation programme, especially as far as the human resources involved are concerned.

  14. RELAP5 based engineering simulator

    SciTech Connect

    Charlton, T.R.; Laats, E.T.; Burtt, J.D.

    1990-01-01

    The INEL Engineering Simulation Center was established in 1988 to provide a modern, flexible, state-of-the-art simulation facility. This facility and two of the major projects which are part of the simulation center, the Advance Test Reactor (ATR) engineering simulator project and the Experimental Breeder Reactor II (EBR-II) advanced reactor control system, have been the subject of several papers in the past few years. Two components of the ATR engineering simulator project, RELAP5 and the Nuclear Plant Analyzer (NPA), have recently been improved significantly. This paper will present an overview of the INEL Engineering Simulation Center, and discuss the RELAP5/MOD3 and NPA/MOD1 codes, specifically how they are being used at the INEL Engineering Simulation Center. It will provide an update on the modifications to these two codes and their application to the ATR engineering simulator project, as well as, a discussion on the reactor system representation, control system modeling, two phase flow and heat transfer modeling. It will also discuss how these two codes are providing desktop, stand-alone reactor simulation. 12 refs., 2 figs.

  15. Multicanonical simulations of some peptides

    NASA Astrophysics Data System (ADS)

    Arkın, H.; Yaşar, F.; Çelik, T.; Berg, B. A.; Meirovitch, H.

    2002-08-01

    A brief discussion of the multicanonical simulation method is given and the results of our simulations of the peptides Leu-enkephalin and deltorphin (in vacuum) are presented. For Leu-enkephalin the determination of the a priori unknown multicanonical weight factors by a recursion is demonstrated, a comparison to the canonical simulations at fixed temperature is done and the effectiveness of the multicanonical simulation method is discussed. Ramachandran plots are shown for deltorphin and interpreted in favor of a funnel kind of picture.

  16. Shuttle bioresearch laboratory breadboard simulations

    NASA Technical Reports Server (NTRS)

    Taketa, S. T.

    1975-01-01

    Laboratory breadboard simulations (Tests I and II) were conducted to test concepts and assess problems associated with bioresearch support equipment, facilities, and operational integration for conducting manned earth orbital Shuttle missions. This paper describes Test I and discusses the major observations made in Test II. The tests emphasized candidate experiment protocols and requirements: Test I for biological research and Test II for crew members (simulated), subhuman primates, and radioisotope tracer studies on lower organisms. The procedures and approaches developed for these simulation activities could form the basis for Spacelab simulations and developing preflight integration, testing, and logistics of flight payloads.

  17. Training and Simulation in Otolaryngology

    PubMed Central

    Wiet, Gregory J.; Stredney, Don; Wan, Dinah

    2011-01-01

    This article focuses on key issues surrounding the needs and application of simulation technologies for technical skills training in otolaryngology. The discussion includes an overview of key topics in training and learning, the application of these issues in simulation environments, and the subsequent applications of these simulation environments to the field of otolaryngology. Examples of past applications are presented, with discussion of how the interplay of cultural changes in surgical training in general, along with the rapid advancements in technology have shaped and influenced their adoption and adaptation. The authors conclude with emerging trends and potential influences advanced simulation and training will have on technical skills training in otolaryngology. PMID:22032486

  18. Block Oriented Simulation System (BOSS)

    NASA Technical Reports Server (NTRS)

    Ratcliffe, Jaimie

    1988-01-01

    Computer simulation is assuming greater importance as a flexible and expedient approach to modeling system and subsystem behavior. Simulation has played a key role in the growth of complex, multiple access space communications such as those used by the space shuttle and the TRW-built Tracking and Data Relay Satellites (TDRS). A powerful new simulator for use in designing and modeling the communication system of NASA's planned Space Station is being developed. Progress to date on the Block (Diagram) Oriented Simulation System (BOSS) is described.

  19. Microarray simulator as educational tool.

    PubMed

    Ruusuvuori, Pekka; Nykter, Matti; Mäkiraatikka, Eeva; Lehmussola, Antti; Korpelainen, Tomi; Erkkilä, Timo; Yli-Harja, Olli

    2007-01-01

    As many real-world applications, microarray measurements are inapplicable for large-scale teaching purposes due to their laborious preparation process and expense. Fortunately, many phases of the array preparation process can be efficiently demonstrated by using a software simulator tool. Here we propose the use of microarray simulator as an aiding tool in teaching of computational biology. Three case studies on educational use of the simulator are presented, which demonstrate the effect of gene knock-out, synthetic time series, and effect of noise sources. We conclude that the simulator, used for teaching the principles of microarray measurement technology, proved to be a useful tool in education.

  20. A Lunar Surface Operations Simulator

    NASA Technical Reports Server (NTRS)

    Nayar, H.; Balaram, J.; Cameron, J.; Jain, A.; Lim, C.; Mukherjee, R.; Peters, S.; Pomerantz, M.; Reder, L.; Shakkottai, P.; Wall, S,

    2008-01-01

    The Lunar Surface Operations Simulator (LSOS) is being developed to support planning and design of space missions to return astronauts to the moon. Vehicles, habitats, dynamic and physical processes and related environment systems are modeled and simulated in LSOS to assist in the visualization and design optimization of systems for lunar surface operations. A parametric analysis tool and a data browser were also implemented to provide an intuitive interface to run multiple simulations and review their results. The simulator and parametric analysis capability are described in this paper.

  1. Computer simulation of astrophysical plasmas

    NASA Technical Reports Server (NTRS)

    Max, Claire E.

    1991-01-01

    The role of sophisticated numerical models and simulations in the field of plasma astrophysics is discussed. The need for an iteration between microphysics and macrophysics in order for astrophysical plasma physics to produce quantitative results that can be related to astronomical data is stressed. A discussion on computational requirements for simulations of astrophysical plasmas contrasts microscopic plasma simulations with macroscopic system models. An overview of particle-in-cell simulations (PICS) is given and two examples of PICS of astrophysical plasma are discussed including particle acceleration by collisionless shocks in relativistic plasmas and magnetic field reconnection in astrophysical plasmas.

  2. Chemical simulation of greywater.

    PubMed

    Abed, Suhail Najem; Scholz, Miklas

    2016-01-01

    Sustainable water resources management attracts considerable attention in today's world. Recycling and reuse of both wastewater and greywater are becoming more attractive. The strategy is to protect ecosystem services by balancing the withdrawal of water and the disposal of wastewater. In the present study, a timely and novel synthetic greywater composition has been proposed with respect to the composition of heavy metals, nutrients and organic matter. The change in water quality of the synthetic greywater due to increasing storage time was monitored to evaluate the stability of the proposed chemical formula. The new greywater is prepared artificially using analytical-grade chemicals to simulate either low (LC) or high (HC) pollutant concentrations. The characteristics of the synthetic greywater were tested (just before starting the experiment, after two days and a week of storage under real weather conditions) and compared to those reported for real greywater. Test results for both synthetic greywater types showed great similarities with the physiochemical properties of published findings concerning real greywater. Furthermore, the synthetic greywater is relatively stable in terms of its characteristics for different storage periods. However, there was a significant (p < .05) reduction in 5-day biochemical oxygen demand (BOD5) for both low (LC) and high (HC) concentrations of greywater after two days of storage with reductions of 62% and 55%, respectively. A significant (p < .05) change was also noted for the reduction (70%) of nitrate-nitrogen (NO3-N) concerning HC greywater after seven days of storage.

  3. Laser Ranging Simulation Program

    NASA Technical Reports Server (NTRS)

    Piazolla, Sabino; Hemmati, Hamid; Tratt, David

    2003-01-01

    Laser Ranging Simulation Program (LRSP) is a computer program that predicts selected aspects of the performances of a laser altimeter or other laser ranging or remote-sensing systems and is especially applicable to a laser-based system used to map terrain from a distance of several kilometers. Designed to run in a more recent version (5 or higher) of the MATLAB programming language, LRSP exploits the numerical and graphical capabilities of MATLAB. LRSP generates a graphical user interface that includes a pop-up menu that prompts the user for the input of data that determine the performance of a laser ranging system. Examples of input data include duration and energy of the laser pulse, the laser wavelength, the width of the laser beam, and several parameters that characterize the transmitting and receiving optics, the receiving electronic circuitry, and the optical properties of the atmosphere and the terrain. When the input data have been entered, LRSP computes the signal-to-noise ratio as a function of range, signal and noise currents, and ranging and pointing errors.

  4. 3D Surgical Simulation

    PubMed Central

    Cevidanes, Lucia; Tucker, Scott; Styner, Martin; Kim, Hyungmin; Chapuis, Jonas; Reyes, Mauricio; Proffit, William; Turvey, Timothy; Jaskolka, Michael

    2009-01-01

    This paper discusses the development of methods for computer-aided jaw surgery. Computer-aided jaw surgery allows us to incorporate the high level of precision necessary for transferring virtual plans into the operating room. We also present a complete computer-aided surgery (CAS) system developed in close collaboration with surgeons. Surgery planning and simulation include construction of 3D surface models from Cone-beam CT (CBCT), dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and bony segment repositioning. A virtual setup can be used to manufacture positioning splints for intra-operative guidance. The system provides further intra-operative assistance with the help of a computer display showing jaw positions and 3D positioning guides updated in real-time during the surgical procedure. The CAS system aids in dealing with complex cases with benefits for the patient, with surgical practice, and for orthodontic finishing. Advanced software tools for diagnosis and treatment planning allow preparation of detailed operative plans, osteotomy repositioning, bone reconstructions, surgical resident training and assessing the difficulties of the surgical procedures prior to the surgery. CAS has the potential to make the elaboration of the surgical plan a more flexible process, increase the level of detail and accuracy of the plan, yield higher operative precision and control, and enhance documentation of cases. Supported by NIDCR DE017727, and DE018962 PMID:20816308

  5. Error coding simulations

    NASA Technical Reports Server (NTRS)

    Noble, Viveca K.

    1993-01-01

    There are various elements such as radio frequency interference (RFI) which may induce errors in data being transmitted via a satellite communication link. When a transmission is affected by interference or other error-causing elements, the transmitted data becomes indecipherable. It becomes necessary to implement techniques to recover from these disturbances. The objective of this research is to develop software which simulates error control circuits and evaluate the performance of these modules in various bit error rate environments. The results of the evaluation provide the engineer with information which helps determine the optimal error control scheme. The Consultative Committee for Space Data Systems (CCSDS) recommends the use of Reed-Solomon (RS) and convolutional encoders and Viterbi and RS decoders for error correction. The use of forward error correction techniques greatly reduces the received signal to noise needed for a certain desired bit error rate. The use of concatenated coding, e.g. inner convolutional code and outer RS code, provides even greater coding gain. The 16-bit cyclic redundancy check (CRC) code is recommended by CCSDS for error detection.

  6. Simulation of Pellet Ablation

    NASA Astrophysics Data System (ADS)

    Parks, P. B.; Ishizaki, Ryuichi

    2000-10-01

    In order to clarify the structure of the ablation flow, 2D simulation is carried out with a fluid code solving temporal evolution of MHD equations. The code includes electrostatic sheath effect at the cloud interface.(P.B. Parks et al.), Plasma Phys. Contr. Fusion 38, 571 (1996). An Eulerian cylindrical coordinate system (r,z) is used with z in a spherical pellet. The code uses the Cubic-Interpolated Psudoparticle (CIP) method(H. Takewaki and T. Yabe, J. Comput. Phys. 70), 355 (1987). that divides the fluid equations into non-advection and advection phases. The most essential element of the CIP method is in calculation of the advection phase. In this phase, a cubic interpolated spatial profile is shifted in space according to the total derivative equations, similarly to a particle scheme. Since the profile is interpolated by using the value and the spatial derivative value at each grid point, there is no numerical oscillation in space, that often appears in conventional spline interpolation. A free boundary condition is used in the code. The possibility of a stationary shock will also be shown in the presentation because the supersonic ablation flow across the magnetic field is impeded.

  7. Fading channel simulator

    DOEpatents

    Argo, Paul E.; Fitzgerald, T. Joseph

    1993-01-01

    Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

  8. Simulated Associating Polymer Networks

    NASA Astrophysics Data System (ADS)

    Billen, Joris

    Telechelic associating polymer networks consist of polymer chains terminated by endgroups that have a different chemical composition than the polymer backbone. When dissolved in a solution, the endgroups cluster together to form aggregates. At low temperature, a strongly connected reversible network is formed and the system behaves like a gel. Telechelic networks are of interest since they are representative for biopolymer networks (e.g. F-actin) and are widely used in medical applications (e.g. hydrogels for tissue engineering, wound dressings) and consumer products (e.g. contact lenses, paint thickeners). In this thesis such systems are studied by means of a molecular dynamics/Monte Carlo simulation. At first, the system in rest is studied by means of graph theory. The changes in network topology upon cooling to the gel state, are characterized. Hereto an extensive study of the eigenvalue spectrum of the gel network is performed. As a result, an in-depth investigation of the eigenvalue spectra for spatial ER, scale-free, and small-world networks is carried out. Next, the gel under the application of a constant shear is studied, with a focus on shear banding and the changes in topology under shear. Finally, the relation between the gel transition and percolation is discussed.

  9. Reactor Simulator Testing Overview

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.

    2013-01-01

    OBJECTIVE: Integrated testing of the TDU components TESTING SUMMARY: a) Verify the operation of the core simulator, the instrumentation and control system, and the ground support gas and vacuum test equipment. b) Thermal test heat regeneration design aspect of a cold trap purification filter. c) Pump performance test at pump voltages up to 150 V (targeted mass flow rate of 1.75 kg/s was not obtained in the RxSim at the originally constrained voltage of 120 V). TESTING HIGHLIGHTS: a) Gas and vacuum ground support test equipment performed effectively for NaK fill, loop pressurization, and NaK drain operations. b) Instrumentation and control system effectively controlled loop temperature and flow rates or pump voltage to targeted settings. c) Cold trap design was able to obtain the targeted cold temperature of 480 K. An outlet temperature of 636 K was obtained which was lower than the predicted 750 K but 156 K higher than the cold temperature indicating the design provided some heat regeneration. d) ALIP produce a maximum flow rate of 1.53 kg/s at 800 K when operated at 150 V and 53 Hz.

  10. Cellular Array Processing Simulation

    NASA Astrophysics Data System (ADS)

    Lee, Harry C.; Preston, Earl W.

    1981-11-01

    The Cellular Array Processing Simulation (CAPS) system is a high-level image language that runs on a multiprocessor configuration. CAPS is interpretively decoded on a conventional minicomputer with all image operation instructions executed on an array processor. The synergistic environment that exists between the minicomputer and the array processor gives CAPS its high-speed throughput, while maintaining a convenient conversational user language. CAPS was designed to be both modular and table driven so that it can be easily maintained and modified. CAPS uses the image convolution operator as one of its primitives and performs this cellular operation by decomposing it into parallel image steps that are scheduled to be executed on the array processor. Among its features is the ability to observe the imagery in real time as a user's algorithm is executed. This feature reduces the need for image storage space, since it is feasible to retain only original images and produce resultant images when needed. CAPS also contains a language processor that permits users to develop re-entrant image processing subroutines or algorithms.

  11. Simulations of Enhanced Confinement

    NASA Astrophysics Data System (ADS)

    Dorland, W.; Kotschenreuther, M.; Liu, Q. P.; Jones, C. S.; Beer, M. A.; Hammett, G. W.

    1996-11-01

    Most existing tokamaks routinely achieve enhanced confinement regimes. Designs for new, larger tokamaks therefore are typically predicated upon reliable enhanced confinement performance. However, most enhanced confinement regimes rely (to some degree) upon sheared E×B flows to stabilize the turbulence that otherwise limits the confinement. For example, the pedestal H-mode transport barrier is typically attributed to shear stabilization [Biglari, Diamond and Terry, Phys. Fl. B, 2 1 (1990)]. Unfortunately, it is easily shown that sheared E×B stabilization of microinstabilities such as the ITG mode does not scale favorably with machine size. Here, using nonlinear gyrofluid simulations in general geometry, we attempt to quantify the confinement enhancement that can be expected from velocity shear stabilization for conventional reactor plasmas. We also consider other microinstability stabilization mechanisms(See related presentations by Beer, Kotschenreuther, Manickam, and Ramos, this conference.) (strong density peaking, Shafranov shift stabilization, dots) and unconventional reactor configurations.^2 Experimental datasets from JET, DIII-D, C-Mod and TFTR are analyzed, and ITER operation is considered.

  12. GRB Simulations in GLAST

    SciTech Connect

    Omodei, Nicola; Battelino, Milan; Komin, Nukri; Longo, Francesco; McEnery, Julie; Ryde, Felix; /Denver U.

    2007-10-22

    The Gamma-ray Large Area Space Telescope (GLAST), scheduled to be launched in fall of 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT) is a pair conversion telescope built with a high precision silicon tracker, a segmented CsI electromagnetic calorimeter and a plastic anticoincidence shield. The LAT will survey the sky in the energy range between 20 MeV to more than 300 GeV, shedding light on many issues left open by its highly successful predecessor EGRET. LAT will observe Gamma-Ray Bursts (GRB) in an energy range never explored before; to tie these frontier observations to the better-known properties at lower energies, a second instrument, the GLAST Burst Monitor (GBM) will provide important spectra and timing in the 10 keV to 30 MeV range. We briefly present the instruments onboard the GLAST satellite, their synergy in the GRB observations and the work done so far by the collaboration in simulation, analysis, and GRB sensitivity estimation.

  13. GRB Simulations in GLAST

    SciTech Connect

    Omodei, Nicola; Battelino, Milan; Komin, Nukri; Longo, Francesco; McEnery, Julie; Norris, Jay; Ryde, Felix

    2007-05-01

    The Gamma-ray Large Area Space Telescope (GLAST), scheduled to be launched in fall of 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT) is a pair conversion telescope built with a high precision silicon tracker, a segmented CsI electromagnetic calorimeter and a plastic anticoincidence shield. The LAT will survey the sky in the energy range between 20 MeV to more than 300 GeV, shedding light on many issues left open by its highly successful predecessor EGRET. LAT will observe Gamma-Ray Bursts (GRB) in an energy range never explored before; to tie these frontier observations to the better-known properties at lower energies, a second instrument, the GLAST Burst Monitor (GBM) will provide important spectra and timing in the 10 keV to 30 MeV range. We briefly present the instruments onboard the GLAST satellite, their synergy in the GRB observations and the work done so far by the collaboration in simulation, analysis, and GRB sensitivity estimation.

  14. SSPX simulation model

    SciTech Connect

    Fowler, T K

    1999-09-20

    An analytical approximation to an R-L-C circuit representing SSPX is shown to reproduce the observed capacitor bank efficiency and gun optimization data. As in the SPICE code, the spheromak gun is represented by a fixed resistance chosen to balance energy transfer to the gun. A revised estimate of the magnetic decay time in SSPX Shot 1822 then brings our estimate of the gun efficiency itself in line with the observed spheromak magnetic field for this shot. Prompted by these successes, we present a turbulence-based theoretical model for the spheromak resistance that can be implemented in the SPICE code, of the form: R{sub s} = {kappa}I (1-I{sub 0}/I){sup 2} where I is the gun current, I{sub 0} = ({Lambda}{sub 0}/{mu}{sub 0}){Phi} with bias flux and Taylor eigenvalue {lambda}{sub 0}, and {kappa} is a coefficient based on the magnetic turbulence model employed in Dan Hua's spheromak simulation code. The value of {kappa} giving a good energy balance (around 0.1 m{Omega}/KA) implies substantial turbulence levels. Implementing our model in SPICE would provide a calibration for theoretical calculations of the turbulence. Our analytic approximation to the SPICE code provides guidance to optimize future performance in SSPX, the greatest benefit appearing to come from reducing or eliminating the protective resistor to increase bank efficiency. Eliminating the resistor altogether doubles the bank efficiency and the spheromak magnetic energy.

  15. Thermoforming simulation with FEA

    SciTech Connect

    Luca, P. de; Pickett, A.K.; Johnson, A.F.

    1996-09-01

    This article describes how the ability to produce high-quality, lightweight structural parts quickly with complex shapes promises to make thermoforming competitive with conventional metal-stamping methods. Thermoforming--the press-forming of continuous fiber-reinforced-thermoplastic (FRTP) sheets--is a promising option for fabricating lightweight structural composite components. Thermoplastic polymers offer improved mechanical and physical properties compared with thermoset polymers, and perhaps most important for industry, they make rapid part production possible using the press-forming process. Despite its promise, thermoforming has not been used to its full potential because tool designers generally rely on trial and error to obtain a detailed understanding of how well this process lends itself to producing a particular part. Because trial-and-error methods are costly and inefficient, tool designers typically cannot gain the sophisticated understanding of the process needed to optimize it for the particular part at hand. Recent advances in the finite-element method may make it easier for tool designers to obtain the insights that have typically come from trial and error. An explicit finite-element code has been developed to simulate the thermoforming process, thereby enabling tool designers to experiment on a computer. The codes use detailed temperature-dependent rheological models to account for intraply shearing, squeeze flow, fiber reorientation, and fiber buckling. They also rely on advanced friction laws--both temperature- and pressure-dependent--to account for the interply sliding mechanism between plies.

  16. MJO Simulation Diagnostics

    SciTech Connect

    Waliser, D; Sperber, K; Hendon, H; Kim, D; Maloney, E; Wheeler, M; Weickmann, K; Zhang, C; Donner, L; Gottschalck, J; Higgins, W; Kang, I; Legler, D; Moncrieff, M; Schubert, S; Stern, W; Vitart, F; Wang, B; Wang, W; Woolnough, S

    2008-06-02

    The Madden-Julian Oscillation (MJO) interacts with, and influences, a wide range of weather and climate phenomena (e.g., monsoons, ENSO, tropical storms, mid-latitude weather), and represents an important, and as yet unexploited, source of predictability at the subseasonal time scale. Despite the important role of the MJO in our climate and weather systems, current global circulation models (GCMs) exhibit considerable shortcomings in representing this phenomenon. These shortcomings have been documented in a number of multi-model comparison studies over the last decade. However, diagnosis of model performance has been challenging, and model progress has been difficult to track, due to the lack of a coherent and standardized set of MJO diagnostics. One of the chief objectives of the US CLIVAR MJO Working Group is the development of observation-based diagnostics for objectively evaluating global model simulations of the MJO in a consistent framework. Motivation for this activity is reviewed, and the intent and justification for a set of diagnostics is provided, along with specification for their calculation, and illustrations of their application. The diagnostics range from relatively simple analyses of variance and correlation, to more sophisticated space-time spectral and empirical orthogonal function analyses. These diagnostic techniques are used to detect MJO signals, to construct composite life-cycles, to identify associations of MJO activity with the mean state, and to describe interannual variability of the MJO.

  17. Plasma Theory and Simulation.

    DTIC Science & Technology

    1979-09-30

    mode In all of Davidson’s equations, there is a factor of /2- difference in vti due 2 to his definition of T.i =m v ti12. -3- 𔃺-1 10-2- 1 0- 10-51 0.3...v E.6 max N~ -10- 0.6 v x 0.4 -0.2 a -0.4 0 1.0 2.0 3.0 4.0 5.0 6.0 16 12 8 4 (b) -0.4 -0.2 Vph -0. -. 2 0.0 0.2 0.4 A vx FIG. 5 Simulation (many mode...Drift Instability", Phys. Fluids 21, 1017 (1978). l mj 12 0.6 . . . . . . vx A 0.4. -0.2 (a) -0.4x 0 10 2.0 3.0 4.0 5.0 6.0 16 12 8 4 (b) Vph -0.4 -0.2

  18. Methods of sound simulation and applications in flight simulators

    NASA Technical Reports Server (NTRS)

    Gaertner, K. P.

    1980-01-01

    An overview of methods for electronically synthesizing sounds is presented. A given amount of hardware and computer capacity places an upper limit on the degree and fidelity of realism of sound simulation which is attainable. Good sound realism for aircraft simulators can be especially expensive because of the complexity of flight sounds and their changing patterns through time. Nevertheless, the flight simulator developed at the Research Institute for Human Engineering, West Germany, shows that it is possible to design an inexpensive sound simulator with the required acoustic properties using analog computer elements. The characteristics of the sub-sound elements produced by this sound simulator for take-off, cruise and approach are discussed.

  19. Interdisciplinary Simulation Using the Cardiopulmonary Bypass Simulator (CPBS)©

    PubMed Central

    Mendel, Shaun

    2014-01-01

    Abstract: Interdisciplinary education offerings between students of cardiovascular science and nurse anesthesia are uncommon despite the collaborative nature of these disciplines. The dual purpose of this article is to describe a method for interdisciplinary simulation and to report survey responses provided by participants. An interdisciplinary simulation session using concurrent use of the cardiopulmonary bypass simulator and the emergency care simulator is described. Interdisciplinary perceptions before and after the event were surveyed using the revised Interdisciplinary Education Perception Scale. Statistically significant differences between baseline and final survey responses were observed in the total score and within the areas of competency and perception of cooperation. Emerging simulation technologies and novel combinations of existing devices can facilitate meaningful interdisciplinary educational opportunities for health science students. PMID:26357799

  20. Mathematical simulation of power conditioning systems. Volume 1: Simulation of elementary units. Report on simulation methodology

    NASA Technical Reports Server (NTRS)

    Prajous, R.; Mazankine, J.; Ippolito, J. C.

    1978-01-01

    Methods and algorithms used for the simulation of elementary power conditioning units buck, boost, and buck-boost, as well as shunt PWM are described. Definitions are given of similar converters and reduced parameters. The various parts of the simulation to be carried out are dealt with; local stability, corrective network, measurements of input-output impedance and global stability. A simulation example is given.

  1. Simulations of chemical catalysis

    NASA Astrophysics Data System (ADS)

    Smith, Gregory K.

    This dissertation contains simulations of chemical catalysis in both biological and heterogeneous contexts. A mixture of classical, quantum, and hybrid techniques are applied to explore the energy profiles and compare possible chemical mechanisms both within the context of human and bacterial enzymes, as well as exploring surface reactions on a metal catalyst. A brief summary of each project follows. Project 1 - Bacterial Enzyme SpvC The newly discovered SpvC effector protein from Salmonella typhimurium interferes with the host immune response by dephosphorylating mitogen-activated protein kinases (MAPKs) with a beta-elimination mechanism. The dynamics of the enzyme substrate complex of the SpvC effector is investigated with a 3.2 ns molecular dynamics simulation, which reveals that the phosphorylated peptide substrate is tightly held in the active site by a hydrogen bond network and the lysine general base is positioned for the abstraction of the alpha hydrogen. The catalysis is further modeled with density functional theory (DFT) in a truncated active-site model at the B3LYP/6-31 G(d,p) level of theory. The truncated model suggested the reaction proceeds via a single transition state. After including the enzyme environment in ab initio QM/MM studies, it was found to proceed via an E1cB-like pathway, in which the carbanion intermediate is stabilized by an enzyme oxyanion hole provided by Lys104 and Tyr158 of SpvC. Project 2 - Human Enzyme CDK2 Phosphorylation reactions catalyzed by kinases and phosphatases play an indispensable role in cellular signaling, and their malfunctioning is implicated in many diseases. Ab initio quantum mechanical/molecular mechanical studies are reported for the phosphoryl transfer reaction catalyzed by a cyclin-dependent kinase, CDK2. Our results suggest that an active-site Asp residue, rather than ATP as previously proposed, serves as the general base to activate the Ser nucleophile. The corresponding transition state features a

  2. Terminological Ambiguity: Game and Simulation

    ERIC Educational Resources Information Center

    Klabbers, Jan H. G.

    2009-01-01

    Since its introduction in academia and professional practice during the 1950s, gaming has been linked to simulation. Although both fields have a few important characteristics in common, they are distinct in their form and underlying theories of knowledge and methodology. Nevertheless, in the literature, hybrid terms such as "gaming/simulation" and…

  3. FEL Simulation Using Distributed Computing

    SciTech Connect

    Einstein, Joshua; Bernabeu Altayo, Gerard; Biedron, Sandra; Freund, Henry; Milton, Stephen; van der Slot, Peter

    2016-06-01

    While simulation tools are available and have been used regularly for simulating light sources, the increasing availability and lower cost of GPU-based processing opens up new opportunities. This poster highlights a method of how accelerating and parallelizing code processing through the use of COTS software interfaces.

  4. Numerical simulation of dusty plasmas

    SciTech Connect

    Winske, D.

    1995-09-01

    The numerical simulation of physical processes in dusty plasmas is reviewed, with emphasis on recent results and unresolved issues. Three areas of research are discussed: grain charging, weak dust-plasma interactions, and strong dust-plasma interactions. For each area, we review the basic concepts that are tested by simulations, present some appropriate examples, and examine numerical issues associated with extending present work.

  5. PETCO: An American Workplace Simulation.

    ERIC Educational Resources Information Center

    Johnston, Amy

    1985-01-01

    PETCO is a simulated corporation used as a teaching tool in the pre-employment training program at the Galang Refugee Processing Center in Indonesia. The refugees in the program are in low-level classes. The use of the simulation allows the staff to present hands-on, task-based learning techniques to address four major concerns of refugees…

  6. SIMULATION GAMING FOR MANAGEMENT DEVELOPMENT.

    ERIC Educational Resources Information Center

    MCKENNEY, JAMES L.

    THE PRESENT HARVARD BUSINESS SCHOOL MANAGEMENT SIMULATION GAME WAS DEVELOPED AS A TEACHING DEVICE FOR CLASSES OF 20 OR MORE STUDENTS GROUPED INTO FOUR- AND FIVE-MAN TEAMS CALLED "FIRMS." EACH FIRM COMPETES WITH OTHERS IN AN "INDUSTRY," AN ECONOMIC ABSTRACTION OF A CONSUMER GOODS MARKET PROGRAMED TO BE SIMULATED ON AN ELECTRONIC…

  7. Conducting Simulation Studies in Psychometrics

    ERIC Educational Resources Information Center

    Feinberg, Richard A.; Rubright, Jonathan D.

    2016-01-01

    Simulation studies are fundamental to psychometric discourse and play a crucial role in operational and academic research. Yet, resources for psychometricians interested in conducting simulations are scarce. This Instructional Topics in Educational Measurement Series (ITEMS) module is meant to address this deficiency by providing a comprehensive…

  8. Electronic Neural-Network Simulator

    NASA Technical Reports Server (NTRS)

    Moopenn, Alex W.; Thakoor, Anilkumar P.; Lambe, John J.

    1988-01-01

    Experimental circuits faster than simulation programs run on digital computers. Serial shift register routes clock pulses C1 to neurons in sequence. Clock pulses C2 interrogate neurons. Neuron interconnection information stored in simulated synapses. Can be expanded to greater complexity.

  9. Aerodynamic Simulation of Indoor Flight

    ERIC Educational Resources Information Center

    De Leon, Nelson; De Leon, Matthew N.

    2007-01-01

    We develop a two-dimensional flight simulator for lightweight (less than 10 g) indoor planes. The simulator consists of four coupled time differential equations describing the plane CG, plane pitch and motor. The equations are integrated numerically with appropriate parameters and initial conditions for two planes: (1) Science Olympiad and (2)…

  10. Simulation Gaming: A Critical Review.

    ERIC Educational Resources Information Center

    Roberts, Nancy

    The review of the empirical literature on simulation gaming categorizes positive, negative, and contradictory aspects of gaming as an educational tool as revealed by the research. The review, which concentrates on simulation games for elementary and secondary school students, is presented in seven sections. Section I presents a brief history of…

  11. Simulating The SSF Information System

    NASA Technical Reports Server (NTRS)

    Deshpande, Govind K.; Kleine, Henry; Younger, Joseph C.; Sanders, Felicia A.; Smith, Jeffrey L.; Aster, Robert W.; Olivieri, Jerry M.; Paul, Lori L.

    1993-01-01

    Freedom Operations Simulation Test (FROST) computer program simulates operation of SSF information system, tracking every packet of data from generation to destination, for both uplinks and downlinks. Collects various statistics concerning operation of system and provides reports of statistics at intervals specified by user. FROST also incorporates graphical-display capability to enhance interpretation of these statistics. Written in SIMSCRIPT 11.5.

  12. Space simulators for laser optics

    NASA Technical Reports Server (NTRS)

    Gardner, Frank H.

    1988-01-01

    Different approaches that are being utilized to test laser optical systems are described. One of the most crucial areas in the testing phase is the stability of the laser optics mounted inside the space simulator. The thermal vacuum system, the refrigeration system, and the space simulator are discussed.

  13. Simulated Laboratory in Digital Logic.

    ERIC Educational Resources Information Center

    Cleaver, Thomas G.

    Design of computer circuits used to be a pencil and paper task followed by laboratory tests, but logic circuit design can now be done in half the time as the engineer accesses a program which simulates the behavior of real digital circuits, and does all the wiring and testing on his computer screen. A simulated laboratory in digital logic has been…

  14. Understanding the Marketplace: A Simulation

    ERIC Educational Resources Information Center

    Vickers, Carole A.

    1978-01-01

    Describes a marketplace simulation game to help students understand the role of competition and the rationale behind buying and selling food and restaurant services. Cutouts (given in the article) are used to simulate elements in the game. Emphasis is on making decisions in business operation and consumer purchases. (MF)

  15. Simulation of spiculated breast lesions

    NASA Astrophysics Data System (ADS)

    Elangovan, Premkumar; Alrehily, Faisal; Pinto, R. Ferrari; Rashidnasab, Alaleh; Dance, David R.; Young, Kenneth C.; Wells, Kevin

    2016-03-01

    Virtual clinical trials are a promising new approach increasingly used for the evaluation and comparison of breast imaging modalities. A key component in such an assessment paradigm is the use of simulated pathology, in particular, simulation of lesions. Breast mass lesions can be generally classified into two categories based on their appearance; nonspiculated masses and spiculated masses. In our previous work, we have successfully simulated non-spiculated masses using a fractal growth process known as diffusion limited aggregation. In this new work, we have extended the DLA model to simulate spiculated lesions by using features extracted from patient DBT images containing spiculated lesions. The features extracted included spicule length, width, curvature and distribution. This information was used to simulate realistic looking spicules which were attached to the surface of a DLA mass to produce a spiculated mass. A batch of simulated spiculated masses was inserted into normal patient images and presented to an experienced radiologist for review. The study yielded promising results with the radiologist rating 60% of simulated lesions in 2D and 50% of simulated lesions in DBT as realistic.

  16. A Monetary Policy Simulation Game

    ERIC Educational Resources Information Center

    Lengwiler, Yvan

    2004-01-01

    The author presents a computer game that puts the player in the role of a central bank governor. The game is a stochastic simulation of a standard reduced form macro model, and the user interacts with this simulation by manipulating the interest rate. The problem the player faces is in many ways quite realistic--just as a real monetary authority,…

  17. Peacebuilding with Games and Simulations

    ERIC Educational Resources Information Center

    Brynen, Rex; Milante, Gary

    2013-01-01

    Simulations and games can offer valuable insight into the management of conflict and the achievement of peace. This special symposium issue of "Simulation & Gaming" examines several such approaches, used in both educational settings and to prepare practitioners to deal with the concrete challenges of peacebuilding. In the introduction, the authors…

  18. Simulations Helping Novices Hone Skills

    ERIC Educational Resources Information Center

    Sawchuk, Stephen

    2011-01-01

    Real-time classroom simulations like TeachME, a University of Central Florida project, offer promise for a host of teacher-training applications. Through them, candidates could learn to work with different groups of students, or practice a discrete skill such as classroom management. Most of all, such simulations give teachers in training the…

  19. Telematics Simulation: Recent Developments & Issues.

    ERIC Educational Resources Information Center

    Sutherland, Janet; Ekker, Knut; Morgan, Konrad; Crookall, David; Carbonell, Amparo Garcia

    Recent developments in Internet technologies have enabled new, more flexible forms of telematic simulation and have raised issues that were not considered in the early days of networked learning. Ultimately, these questions revolve around: (1) the learning cost-effectiveness of telematic simulation (quality and quantity of learning as opposed to…

  20. Detector simulation for the SSC

    SciTech Connect

    Price, L.E.

    1991-01-01

    Detector simulation activities for SSC detector designs are described. Topics include the extensive work to date using existing programs. In addition, the several efforts to extend the capabilities of today's programs are described, as the practical and experimental use of new computing platforms for simulation. Finally, progress in the field is compared with the recommendations of the first workshop in this series in 1987.