1,613 research outputs found

    21st Century Simulation: Exploiting High Performance Computing and Data Analysis

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    This paper identifies, defines, and analyzes the limitations imposed on Modeling and Simulation by outmoded paradigms in computer utilization and data analysis. The authors then discuss two emerging capabilities to overcome these limitations: High Performance Parallel Computing and Advanced Data Analysis. First, parallel computing, in supercomputers and Linux clusters, has proven effective by providing users an advantage in computing power. This has been characterized as a ten-year lead over the use of single-processor computers. Second, advanced data analysis techniques are both necessitated and enabled by this leap in computing power. JFCOM's JESPP project is one of the few simulation initiatives to effectively embrace these concepts. The challenges facing the defense analyst today have grown to include the need to consider operations among non-combatant populations, to focus on impacts to civilian infrastructure, to differentiate combatants from non-combatants, and to understand non-linear, asymmetric warfare. These requirements stretch both current computational techniques and data analysis methodologies. In this paper, documented examples and potential solutions will be advanced. The authors discuss the paths to successful implementation based on their experience. Reviewed technologies include parallel computing, cluster computing, grid computing, data logging, OpsResearch, database advances, data mining, evolutionary computing, genetic algorithms, and Monte Carlo sensitivity analyses. The modeling and simulation community has significant potential to provide more opportunities for training and analysis. Simulations must include increasingly sophisticated environments, better emulations of foes, and more realistic civilian populations. Overcoming the implementation challenges will produce dramatically better insights, for trainees and analysts. High Performance Parallel Computing and Advanced Data Analysis promise increased understanding of future vulnerabilities to help avoid unneeded mission failures and unacceptable personnel losses. The authors set forth road maps for rapid prototyping and adoption of advanced capabilities. They discuss the beneficial impact of embracing these technologies, as well as risk mitigation required to ensure success

    High-performance computing enables simulations to transform education

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    This paper presents the case that education in the 21st Century can only measure up to national needs if technologies developed in the simulation community, further enhanced by the power of high performance computing, are harnessed to supplant traditional didactic instruction. The authors cite their professional experiences in simulation, high performance computing and pedagogical studies to support their thesis that this implementation is not only required, it is feasible, supportable and affordable. Surveying and reporting on work in computer-aided education, this paper will discuss the pedagogical imperatives for group learning, risk management and “hero teacher” surrogates, all being optimally delivered with entity level simulations of varying types. Further, experience and research is adduced to support the thesis that effective implementation of this level of simulation is enabled only by, and is largely dependent upon, high performance computing, especially by the ready utility and acceptable costs of Linux clusters

    Palatini approach to Born-Infeld-Einstein theory and a geometric description of electrodynamics

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    The field equations associated with the Born-Infeld-Einstein action are derived using the Palatini variational technique. In this approach the metric and connection are varied independently and the Ricci tensor is generally not symmetric. For sufficiently small curvatures the resulting field equations can be divided into two sets. One set, involving the antisymmetric part of the Ricci tensor RμνR_{\stackrel{\mu\nu}{\vee}}, consists of the field equation for a massive vector field. The other set consists of the Einstein field equations with an energy momentum tensor for the vector field plus additional corrections. In a vacuum with Rμν=0R_{\stackrel{\mu\nu}{\vee}}=0 the field equations are shown to be the usual Einstein vacuum equations. This extends the universality of the vacuum Einstein equations, discussed by Ferraris et al. \cite{Fe1,Fe2}, to the Born-Infeld-Einstein action. In the simplest version of the theory there is a single coupling constant and by requiring that the Einstein field equations hold to a good approximation in neutron stars it is shown that mass of the vector field exceeds the lower bound on the mass of the photon. Thus, in this case the vector field cannot represent the electromagnetic field and would describe a new geometrical field. In a more general version in which the symmetric and antisymmetric parts of the Ricci tensor have different coupling constants it is possible to satisfy all of the observational constraints if the antisymmetric coupling is much larger than the symmetric coupling. In this case the antisymmetric part of the Ricci tensor can describe the electromagnetic field, although gauge invariance will be broken.Comment: 12 page

    Distributed and Interactive Simulations Operating at Large Scale for Transcontinental Experimentation

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    This paper addresses the use of emerging technologies to respond to the increasing needs for larger and more sophisticated agent-based simulations of urban areas. The U.S. Joint Forces Command has found it useful to seek out and apply technologies largely developed for academic research in the physical sciences. The use of these techniques in transcontinentally distributed, interactive experimentation has been shown to be effective and stable and the analyses of the data find parallels in the behavioral sciences. The authors relate their decade and a half experience in implementing high performance computing hardware, software and user inter-face architectures. These have enabled heretofore unachievable results. They focus on three advances: the use of general purpose graphics processing units as computing accelerators, the efficiencies derived from implementing interest managed routers in distributed systems, and the benefits of effective data management for the voluminous information

    High-performance computing enables simulations to transform education

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    This paper presents the case that education in the 21st Century can only measure up to national needs if technologies developed in the simulation community, further enhanced by the power of high performance computing, are harnessed to supplant traditional didactic instruction. The authors cite their professional experiences in simulation, high performance computing and pedagogical studies to support their thesis that this implementation is not only required, it is feasible, supportable and affordable. Surveying and reporting on work in computer-aided education, this paper will discuss the pedagogical imperatives for group learning, risk management and “hero teacher” surrogates, all being optimally delivered with entity level simulations of varying types. Further, experience and research is adduced to support the thesis that effective implementation of this level of simulation is enabled only by, and is largely dependent upon, high performance computing, especially by the ready utility and acceptable costs of Linux clusters

    Establishing Peer Recovery Support Services to Address the Central Appalachian Opioid Epidemic: The West Virginia Peers Enhancing Education, Recovery, and Survival (WV PEERS) Pilot Program

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    Introduction: Central Appalachia has been disproportionately affected by the opioid epidemic and overdose fatalities. We developed West Virginia Peers Enhancing Education, Recovery, and Survival (WV PEERS), a program based on peer recovery support, to engage individuals using opioids and link them with a range of services. Methods: Community partners providing services to individuals with opioid use disorder (OUD) were identified and collaborations were formalized using a standardized memorandum of understanding. The program was structured to offer ongoing peer recovery support specialist (PRSS) services, not just a one-time referral. A website and cards describing the WV PEERS program were developed and disseminated via community partners and community education sessions. Results: Overall, 1456 encounters with individuals with OUD (mean= 2 encounters per individual) occurred in a variety of community settings over 8 months. The majority of referrals were from harm reduction programs. Overall, 63.9% (n=931) of individuals served by WV PEERS accessed services for substance use disorders and/or mental health problems. Over half (52.3%; n = 487) of individuals entered substance use and/or mental health treatment, and nearly a third (30.4%; n = 283) remained in treatment over six months. Implications: Using the WV PEERS model, PRSSs effectively engaged and linked individuals with OUD to mental health and substance use treatment in rural central Appalachia. Future research is needed to determine whether these services reduce the risk of overdose mortality

    Reconstruction of the joint state of a two-mode Bose-Einstein condensate

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    We propose a scheme to reconstruct the state of a two-mode Bose-Einstein condensate, with a given total number of atoms, using an atom interferometer that requires beam splitter, phase shift and non-ideal atom counting operations. The density matrix in the number-state basis can be computed directly from the probabilities of different counts for various phase shifts between the original modes, unless the beamsplitter is exactly balanced. Simulated noisy data from a two-mode coherent state is produced and the state is reconstructed, for 49 atoms. The error can be estimated from the singular values of the transformation matrix between state and probability data.Comment: 4 pages (REVTeX), 5 figures (PostScript

    Detection of vorticity in Bose-Einstein condensed gases by matter-wave interference

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    A phase-slip in the fringes of an interference pattern is an unmistakable characteristic of vorticity. We show dramatic two-dimensional simulations of interference between expanding condensate clouds with and without vorticity. In this way, vortices may be detected even when the core itself cannot be resolved.Comment: 3 pages, RevTeX, plus 6 PostScript figure

    Pumping two dilute gas Bose-Einstein condensates with Raman light scattering

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    We propose an optical method for increasing the number of atoms in a pair of dilute gas Bose-Einstein condensates. The method uses laser-driven Raman transitions which scatter atoms between the condensate and non-condensate atom fractions. For a range of condensate phase differences there is destructive quantum interference of the amplitudes for scattering atoms out of the condensates. Because the total atom scattering rate into the condensates is unaffected the condensates grow. This mechanism is analogous to that responsible for optical lasing without inversion. Growth using macroscopic quantum interference may find application as a pump for an atom laser.Comment: 4 pages, no figure
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