WorldWideScience

Sample records for distributed interactive simulation

  1. Distributed Interactive Simulation Protocol Extensions

    Science.gov (United States)

    1993-05-28

    8 po -et.-siuulation -load ............................ 39 neu.simulator.event-. bandler .................. 8 po-least...1 ose.zrceniilatn...............391 po-set .exercise.init ializat ion .................. 39 overlay..con -irmation- bandler

  2. Interactive simulations for quantum key distribution

    CERN Document Server

    Kohnle, Antje

    2016-01-01

    Secure communication protocols are becoming increasingly important, e.g. for internet-based communication. Quantum key distribution allows two parties, commonly called Alice and Bob, to generate a secret sequence of 0s and 1s called a key that is only known to themselves. Classically, Alice and Bob could never be certain that their communication was not compromised by a malicious eavesdropper. Quantum mechanics however makes secure communication possible. The fundamental principle of quantum mechanics that taking a measurement perturbs the system (unless the measurement is compatible with the quantum state) also applies to an eavesdropper. Using appropriate protocols to create the key, Alice and Bob can detect the presence of an eavesdropper by errors in their measurements. As part of the QuVis Quantum Mechanics Visualization Project, we have developed a suite of four interactive simulations that demonstrate the basic principles of three different quantum key distribution protocols. The simulations use either...

  3. Simulated Galaxy Interactions as Probes of Merger Spectral Energy Distributions

    CERN Document Server

    Lanz, Lauranne; Zezas, Andreas; Smith, Howard A; Ashby, Matthew L N; Brassington, Nicola; Fazio, Giovanni G; Hernquist, Lars

    2014-01-01

    We present the first systematic comparison of ultraviolet-millimeter spectral energy distributions (SEDs) of observed and simulated interacting galaxies. Our sample is drawn from the Spitzer Interacting Galaxy Survey, and probes a range of galaxy interaction parameters. We use 31 galaxies in 14 systems which have been observed with Herschel, Spitzer, GALEX, and 2MASS. We create a suite of GADGET-3 hydrodynamic simulations of isolated and interacting galaxies with stellar masses comparable to those in our sample of interacting galaxies. Photometry for the simulated systems is then calculated with the SUNRISE radiative transfer code for comparison with the observed systems. For most of the observed systems, one or more of the simulated SEDs match reasonably well. The best matches recover the infrared luminosity and the star formation rate of the observed systems, and the more massive systems preferentially match SEDs from simulations of more massive galaxies. The most morphologically distorted systems in our sa...

  4. Distributed interactive communication in simulated space-dwelling groups.

    Science.gov (United States)

    Brady, Joseph V; Hienz, Robert D; Hursh, Steven R; Ragusa, Leonard C; Rouse, Charles O; Gasior, Eric D

    2004-03-01

    This report describes the development and preliminary application of an experimental test bed for modeling human behavior in the context of a computer generated environment to analyze the effects of variations in communication modalities, incentives and stressful conditions. In addition to detailing the methodological development of a simulated task environment that provides for electronic monitoring and recording of individual and group behavior, the initial substantive findings from an experimental analysis of distributed interactive communication in simulated space dwelling groups are described. Crews of three members each (male and female) participated in simulated "planetary missions" based upon a synthetic scenario task that required identification, collection, and analysis of geologic specimens with a range of grade values. The results of these preliminary studies showed clearly that cooperative and productive interactions were maintained between individually isolated and distributed individuals communicating and problem-solving effectively in a computer-generated "planetary" environment over extended time intervals without benefit of one another's physical presence. Studies on communication channel constraints confirmed the functional interchangeability between available modalities with the highest degree of interchangeability occurring between Audio and Text modes of communication. The effects of task-related incentives were determined by the conditions under which they were available with Positive Incentives effectively attenuating decrements in performance under stressful time pressure.

  5. Addressing the Challenge of Distributed Interactive Simulation With Data Distribution Service

    CERN Document Server

    Hakiri, Akram; Gayraud, Thierry

    2010-01-01

    Real-Time availability of information is of most importance in large scale distributed interactive simulation in network-centric communication. Information generated from multiple federates must be distributed and made available to interested parties and providing the required QoS for consistent communication. The remainder of this paper discuss design alternative for realizing high performance distributed interactive simulation (DIS) application using the OMG Data Distribution Service (DDS), which is a QoS enabled publish/subscribe platform standard for time-critical, data-centric and large scale distributed networks. The considered application, in the civil domain, is used for remote education in driving schools. An experimental design evaluates the bandwidth and the latency performance of DDS and a comparison with the High Level Architecture performance is given.

  6. Dynamic Multicast Grouping Approach in HLA-Based Distributed Interactive Simulation

    Institute of Scientific and Technical Information of China (English)

    DAI Zhong-jian; HOU Chao-zhen

    2005-01-01

    In order to improve the efficiency of data distributed management service in distributed interactive simulation based on high level architecture (HLA) and to reduce the network traffic and save the system resource, the approaches of multicast grouping in HLA-based distributed interactive simulation are discussed. Then a new dynamic multicast grouping approach is proposed. This approach is based on the current publication and subscription region in the process of simulation. The results of simulation experiment show that this approach can significantly reduce the message overhead and use fewer multicast groups.

  7. Experimental grid access for dynamic discovery and data transfer in distributed interactive simulation systems

    NARCIS (Netherlands)

    A. Tirado-Ramos; K. Zajac; Z. Zhao; P.M.A. Sloot; G.D. van Albada; M. Bubak

    2003-01-01

    Interactive Problem Solving Environments (PSEs) offer an integrated approach for constructing and running complex systems, such as distributed simulation systems. New distributed infrastructures, like the Grid, support the access to a large variety of core services and resources that can be used by

  8. Innovative Training Concepts for Use in Distributed Interactive Simulation (DIS) Environments

    Science.gov (United States)

    1993-07-30

    Atwood , N. K., Sawyer, A. R., Quinkert, K.A., Heiden, C. K., Smith, P. G. and Schwartz, B. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) B. PERFORMING...Use in Distributed Interactive Simulation (DIS) EnvironmentsI Beverly J. Winsch Nancy K. Atwood Alicia R. Sawyer BDM Federal, Inc. Kathleen A...time. In addition to the authors, the BDM Federal, Inc. research staff participating in the effort included Mr. Silver Campbell, Ms. Margaret Shay and

  9. Distributed interactive simulation (DIS) systems engineering fidelity, management, and usability issues in DIS exercises

    Science.gov (United States)

    McDonald, Bruce

    1995-06-01

    This paper is intended to familiarize the sensor design engineer with the capabilities of distributed interactive simulation (DIS) to support the design and test of sensor system. We define DIS terms and then discuss what DIS does to support the design and development process. Fist, DIS provides access to reusable simulation and network components that reduce the cost of tests. Second, it makes user personnel available to interact in the simulation without the expense of bringing the participants to the test site. Third, DIS has reusable computer- generated forces that provide the engineer with sufficient threats and friendlies to load the sensor system in an affordable exercise. Examples of how an engineer would design a study to take advantage of DIS capabilities are provided.

  10. A unified framework for spiking and gap-junction interactions in distributed neuronal network simulations

    Directory of Open Access Journals (Sweden)

    Jan eHahne

    2015-09-01

    Full Text Available Contemporary simulators for networks of point and few-compartment model neurons come with a plethora of ready-to-use neuron and synapse models and support complex network topologies. Recent technological advancements have broadened the spectrum of application further to the efficient simulation of brain-scale networks on supercomputers. In distributed network simulations the amount of spike data that accrues per millisecond and process is typically low, such that a common optimization strategy is to communicate spikes at relatively long intervals, where the upper limit is given by the shortest synaptic transmission delay in the network. This approach is well-suited for simulations that employ only chemical synapses but it has so far impeded the incorporation of gap-junction models, which require instantaneous neuronal interactions. Here, we present a numerical algorithm based on a waveform-relaxation technique which allows for network simulations with gap junctions in a way that is compatible with the delayed communication strategy. Using a reference implementation in the NEST simulator, we demonstrate that the algorithm and the required data structures can be smoothly integrated with existing code such that they complement the infrastructure for spiking connections. To show that the unified framework for gap-junction and spiking interactions achieves high performance and delivers high accuracy...

  11. Development of a Web-Based Distributed Interactive Simulation (DIS) Environment Using JavaScript

    Science.gov (United States)

    2014-09-01

    present technologies for developing a small-scale and interactive simulation. A. MOTIVATION With the prosperity of the Internet, more and more web...between ECEF and ENU (east, north and up), which is a set 34 of local coordinates with a given geodetic point. Figure 16 presents the coordinate systems...position. Dead reckoning can be utilized to cover an entity’s stutters caused by the heartbeat period. The demonstration tank game used dead reckoning

  12. A Virtual Environment for Satellite Modeling and Orbital Analysis in a Distributed Interactive Simulation

    Science.gov (United States)

    1993-12-01

    center of mass to the center of the earth. Interactive modification of the heading or pitch components of satellite orientation is not factored in to... satellite orientation and orientation by simulating thruster-firing activities. Both systems accept actual satellite telemetry for propagating models in the...model by applying rigid body dynamics. Model satellite sensor capabilities to determine FOV. Process actual satellite orientation data. _ __ Incorporate

  13. QoS-enabled ANFIS Dead Reckoning Algorithm for Distributed Interactive Simulation

    CERN Document Server

    Hakiri, Akram

    2010-01-01

    Dead Reckoning mechanisms are usually used to estimate the position of simulated entity in virtual environment. However, this technique often ignores available contextual information that may be influential to the state of an entity, sacrificing remote predictive accuracy in favor of low computational complexity. A novel extension of Dead Reckoning is suggested in this paper to increase the network availability and fulfill the required Quality of Service in large scale distributed simulation application. The proposed algorithm is referred to as ANFIS Dead Reckoning, which stands for Adaptive Neuro-based Fuzzy Inference System Dead Reckoning is based on a fuzzy inference system which is trained by the learning algorithm derived from the neuronal networks and fuzzy inference theory. The proposed mechanism takes its based on the optimization approach to calculate the error threshold violation in networking games. Our model shows it primary benefits especially in the decision making of the behavior of simulated e...

  14. Characteristics of the mixing volume model with the interactions among spatially distributed particles for Lagrangian simulations of turbulent mixing

    Science.gov (United States)

    Watanabe, Tomoaki; Nagata, Koji

    2016-11-01

    The mixing volume model (MVM), which is a mixing model for molecular diffusion in Lagrangian simulations of turbulent mixing problems, is proposed based on the interactions among spatially distributed particles in a finite volume. The mixing timescale in the MVM is derived by comparison between the model and the subgrid scale scalar variance equation. A-priori test of the MVM is conducted based on the direct numerical simulations of planar jets. The MVM is shown to predict well the mean effects of the molecular diffusion under various conditions. However, a predicted value of the molecular diffusion term is positively correlated to the exact value in the DNS only when the number of the mixing particles is larger than two. Furthermore, the MVM is tested in the hybrid implicit large-eddy-simulation/Lagrangian-particle-simulation (ILES/LPS). The ILES/LPS with the present mixing model predicts well the decay of the scalar variance in planar jets. This work was supported by JSPS KAKENHI Nos. 25289030 and 16K18013. The numerical simulations presented in this manuscript were carried out on the high performance computing system (NEC SX-ACE) in the Japan Agency for Marine-Earth Science and Technology.

  15. Interactive Reactor Simulation.

    Science.gov (United States)

    Nuttall, Herbert E., Jr.; Himmelblau, David M.

    In the field of chemical engineering, interactive process models can simulate the dynamic behavior and analysis of chemical processes. DYFLO was the process simulation program selected as a foundation for development of interactive programs for computer-assisted instruction (CAI) in chemical engineering. Interactive Computing and time sharing…

  16. Distributed Hardware-in-the-loop simulator for autonomous continuous dynamical systems with spatially constrained interactions

    NARCIS (Netherlands)

    Verburg, D.J.; Papp, Z.; Dorrepaal, M.

    2003-01-01

    The state-of-the-art intelligent vehicle, autonomous guided vehicle and mobile robotics application domains can be described as collection of interacting highly autonomous complex dynamical systems. Extensive formal analysis of these systems – except special cases – is not feasible, consequently the

  17. Interactive CFD simulations

    OpenAIRE

    Duque Lombana, Juan Fernando

    2007-01-01

    This project is about the development of an implementable Interactive Computer Fluid Dynamics methodology -- The range of this work begins with an overview of the current status of computational fluid dynamics simulation software and methodologies, continues with an introduction to what interactive and interactivity mean, develops an all original interactive CFD methodology to follow for the solution of fluid scenarios and finally, the description of the implementation of an interactive solve...

  18. Highly interactive distributed visualization

    NARCIS (Netherlands)

    Scarpa, M.; Belleman, R.G.; Sloot, P.M.A.; de Laat, C.T.A.M.

    2006-01-01

    We report on our iGrid2005 demonstration, called the "Dead Cat Demo"; an example of a highly interactive augmented reality application consisting of software services distributed over a wide-area, high-speed network. We describe our design decisions, analyse the implications of the design on applica

  19. Interactive Foresight Simulation

    DEFF Research Database (Denmark)

    Hansen, Mette Sanne; Rasmussen, Lauge Baungaard; Jacobsen, Peter

    2016-01-01

    The Combined Simulation Approach (CSA) is a way to evaluate risks and address potential unforeseen problems in a more interactive way than what is often observed in practice in companies or sectors. The approach is based on a combination of scenario analysis and discrete-event computer simulation...

  20. Electrostatics interactions in classical simulations.

    Science.gov (United States)

    Cisneros, G Andrés; Babin, Volodymyr; Sagui, Celeste

    2013-01-01

    Electrostatic interactions are crucial for both the accuracy and performance of atomistic biomolecular simulations. In this chapter we review well-established methods and current developments aiming at efficiency and accuracy. Specifically, we review the classical Ewald summations, particle-particle particle-method particle-method Ewald algorithms, multigrid, fast multipole, and local methods. We also highlight some recent developments targeting more accurate, yet classical, representation of the molecular charge distribution.

  1. Interactive Parallel and Distributed Processing

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop; Pagliarini, Luigi

    2010-01-01

    We present the concept of interactive parallel and distributed processing, and the challenges that programmers face in designing interactive parallel and distributed systems. Specifically, we introduce the challenges that are met and the decisions that need to be taken with respect...... to distributedness, master dependency, software behavioural models, adaptive interactivity, feedback, connectivity, topology, island modeling, and user interaction. We introduce the system of modular interactive tiles as a tool for easy, fast, and flexible exploration of these issues, and through examples show how...... to implement interactive parallel and distributed processing with different software behavioural models such as open loop, randomness based, rule based, user interaction based, AI and ALife based software....

  2. Interactive Dynamic-System Simulation

    CERN Document Server

    Korn, Granino A

    2010-01-01

    Showing you how to use personal computers for modeling and simulation, Interactive Dynamic-System Simulation, Second Edition provides a practical tutorial on interactive dynamic-system modeling and simulation. It discusses how to effectively simulate dynamical systems, such as aerospace vehicles, power plants, chemical processes, control systems, and physiological systems. Written by a pioneer in simulation, the book introduces dynamic-system models and explains how software for solving differential equations works. After demonstrating real simulation programs with simple examples, the author

  3. Infrastructure for distributed enterprise simulation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M.M.; Yoshimura, A.S.; Goldsby, M.E. [and others

    1998-01-01

    Traditional discrete-event simulations employ an inherently sequential algorithm and are run on a single computer. However, the demands of many real-world problems exceed the capabilities of sequential simulation systems. Often the capacity of a computer`s primary memory limits the size of the models that can be handled, and in some cases parallel execution on multiple processors could significantly reduce the simulation time. This paper describes the development of an Infrastructure for Distributed Enterprise Simulation (IDES) - a large-scale portable parallel simulation framework developed to support Sandia National Laboratories` mission in stockpile stewardship. IDES is based on the Breathing-Time-Buckets synchronization protocol, and maps a message-based model of distributed computing onto an object-oriented programming model. IDES is portable across heterogeneous computing architectures, including single-processor systems, networks of workstations and multi-processor computers with shared or distributed memory. The system provides a simple and sufficient application programming interface that can be used by scientists to quickly model large-scale, complex enterprise systems. In the background and without involving the user, IDES is capable of making dynamic use of idle processing power available throughout the enterprise network. 16 refs., 14 figs.

  4. Distributed Air Traffic Control Simulator

    Directory of Open Access Journals (Sweden)

    R. Radovanović

    2013-06-01

    Full Text Available During initial training air traffic control students acquire theoretical knowledge in various fields including air traffic management, aircraft performance, air traffic control equipment and systems, navigation and others. This paper proposes a simulator and explains its use and features that allows students to gain a practical insight into their coursework in order to complement their training. The goal of the simulator is to realistically implement all the key functionalities needed to cover the topics that were presented in class. The simulator offers a user friendly, distributed, and multi-role environment that can be deployed on regular PCs. Moreover, this paper discusses and resolves some of the main conceptual and implementational issues that were faced during simulator development.

  5. Air shower simulation and hadronic interactions

    Directory of Open Access Journals (Sweden)

    Ulrich Ralf

    2013-06-01

    Full Text Available The aim of this report of the Working Group on Hadronic Interactions and Air Shower Simulation is to give an overview of the status of the field, emphasizing open questions and a comparison of relevant results of the different experiments. It is shown that an approximate overall understanding of extensive air showers and the corresponding hadronic interactions has been reached. The simulations provide a qualitative description of the bulk of the air shower observables. Discrepancies are however found when the correlation between measurements of the longitudinal shower profile are compared to that of the lateral particle distributions at ground. The report concludes with a list of important problems that should be addressed to make progress in understanding hadronic interactions and, hence, improve the reliability of air shower simulations.

  6. Capstone Renaissance = Simulation + Interaction + DSS.

    Science.gov (United States)

    Jauch, Lawrence R.; And Others

    1989-01-01

    Reviews the development of integrated business policy and strategic management courses, or capstone courses, in business school curricula. A simulation game is described that incorporates the need for computer literacy, decision support systems (DSS), and interaction to effectively meet the needs for a capstone course. (14 references) (LRW)

  7. Quantum simulation with interacting photons

    Science.gov (United States)

    Hartmann, Michael J.

    2016-10-01

    Enhancing optical nonlinearities so that they become appreciable on the single photon level and lead to nonclassical light fields has been a central objective in quantum optics for many years. After this has been achieved in individual micro-cavities representing an effectively zero-dimensional volume, this line of research has shifted its focus towards engineering devices where such strong optical nonlinearities simultaneously occur in extended volumes of multiple nodes of a network. Recent technological progress in several experimental platforms now opens the possibility to employ the systems of strongly interacting photons, these give rise to as quantum simulators. Here we review the recent development and current status of this research direction for theory and experiment. Addressing both, optical photons interacting with atoms and microwave photons in networks of superconducting circuits, we focus on analogue quantum simulations in scenarios where effective photon-photon interactions exceed dissipative processes in the considered platforms.

  8. Quantum Simulation with Interacting Photons

    CERN Document Server

    Hartmann, Michael J

    2016-01-01

    We review the theoretical and experimental developments in recent research on quantum simulators with interacting photons. Enhancing optical nonlinearities so that they become appreciable on the single photon level and lead to nonclassical light fields has been a central objective in quantum optics for many years. After this has been achieved in individual micro-cavities representing an effectively zero-dimensional volume, this line of research has now shifted its focus towards engineering devices where such strong optical nonlinearities simultaneously occur in extended volumes of multiple nodes of a network. Recent technological progress in several experimental platforms now opens the possibility to employ the systems of strongly interacting photons these give rise to as quantum simulators. Here we review the recent development and current status of this research direction for theory and experiment. Addressing both, optical photons interacting with atoms and microwave photons in networks of superconducting c...

  9. Interaction and Impact Studies for Distributed Energy Resource, Transactive Energy, and Electric Grid, using High Performance Computing ?based Modeling and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, B M

    2017-02-10

    The electric utility industry is undergoing significant transformations in its operation model, including a greater emphasis on automation, monitoring technologies, and distributed energy resource management systems (DERMS). With these changes and new technologies, while driving greater efficiencies and reliability, these new models may introduce new vectors of cyber attack. The appropriate cybersecurity controls to address and mitigate these newly introduced attack vectors and potential vulnerabilities are still widely unknown and performance of the control is difficult to vet. This proposal argues that modeling and simulation (M&S) is a necessary tool to address and better understand these problems introduced by emerging technologies for the grid. M&S will provide electric utilities a platform to model its transmission and distribution systems and run various simulations against the model to better understand the operational impact and performance of cybersecurity controls.

  10. Distributed simulation a model driven engineering approach

    CERN Document Server

    Topçu, Okan; Oğuztüzün, Halit; Yilmaz, Levent

    2016-01-01

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

  11. Distribution view: a tool to write and simulate distributions

    OpenAIRE

    Coelho, José; Branco, Fernando; Oliveira, Teresa

    2006-01-01

    In our work we present a tool to write and simulate distributions. This tool allows to write mathematical expressions which can contain not only functions and variables, but also statistical distributions, including mixtures. Each time the expression is evaluated, for all inner distributions, is generated a value according to the distribution and is used for expression value determination. The inversion method can be used in this language, allowing to generate all distributions...

  12. FEL Simulation Using Distributed Computing

    Energy Technology Data Exchange (ETDEWEB)

    Einstein, Joshua [Fermilab; Bernabeu Altayo, Gerard [Fermilab; Biedron, Sandra [Ljubljana U.; Freund, Henry [Colorado State U., Fort Collins; Milton, Stephen [Colorado State U., Fort Collins; van der Slot, Peter [Colorado State U., Fort Collins

    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.

  13. Automated Distributed Simulation in Ptolemy II

    DEFF Research Database (Denmark)

    Lázaro Cuadrado, Daniel; Ravn, Anders Peter; Koch, Peter

    2007-01-01

    the ensuing communication and synchronization problems. Very often the designer has to explicitly specify extra information concerning distribution for the framework to make an effort to exploit parallelism. This paper presents Automated Distributed Simulation (ADS), which allows the designer to forget about......Despite the well known advantages of distributed processing for intensive computations like simulation, frameworks often fail to exploit them. A distributed simulation is harder to develop than a sequential one, because it is necessary to interface and map activities to processors and handle...... distribution concerns while benefiting from the advantages. ADS relies on the actor formalism. It is realized as an open source implementation for the Ptolemy II simulation framework. Experiments compare different topologies, granularities and number of blocks, achieving linear speedups for practical cases. We...

  14. The Schlueter distribution: theory and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Shutler, P M E; Springham, S V; Martinez, J C [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2007-11-15

    The distribution of molecular speeds for a hard spheres gas in the microcanonical ensemble follows the Schlueter distribution when the number of molecules is small, converging to the classical Maxwell distribution in the large number limit. We present a derivation of the Schlueter distribution, obtained from Khinchin's derivation of the factorization of the density of states, which is simpler and shorter than those currently available. We also verify its predictions for three-dimensional (3D) hard spheres using a desktop computer simulation, whereas previous studies have simulated only 2D hard discs.

  15. Dynamics simulations for engineering macromolecular interactions

    Science.gov (United States)

    Robinson-Mosher, Avi; Shinar, Tamar; Silver, Pamela A.; Way, Jeffrey

    2013-06-01

    The predictable engineering of well-behaved transcriptional circuits is a central goal of synthetic biology. The artificial attachment of promoters to transcription factor genes usually results in noisy or chaotic behaviors, and such systems are unlikely to be useful in practical applications. Natural transcriptional regulation relies extensively on protein-protein interactions to insure tightly controlled behavior, but such tight control has been elusive in engineered systems. To help engineer protein-protein interactions, we have developed a molecular dynamics simulation framework that simplifies features of proteins moving by constrained Brownian motion, with the goal of performing long simulations. The behavior of a simulated protein system is determined by summation of forces that include a Brownian force, a drag force, excluded volume constraints, relative position constraints, and binding constraints that relate to experimentally determined on-rates and off-rates for chosen protein elements in a system. Proteins are abstracted as spheres. Binding surfaces are defined radially within a protein. Peptide linkers are abstracted as small protein-like spheres with rigid connections. To address whether our framework could generate useful predictions, we simulated the behavior of an engineered fusion protein consisting of two 20 000 Da proteins attached by flexible glycine/serine-type linkers. The two protein elements remained closely associated, as if constrained by a random walk in three dimensions of the peptide linker, as opposed to showing a distribution of distances expected if movement were dominated by Brownian motion of the protein domains only. We also simulated the behavior of fluorescent proteins tethered by a linker of varying length, compared the predicted Förster resonance energy transfer with previous experimental observations, and obtained a good correspondence. Finally, we simulated the binding behavior of a fusion of two ligands that could

  16. A distributed blackboard architecture for interactive data visualization

    NARCIS (Netherlands)

    Liere, R. van; Harkes, J.A.; Leeuw, W.C. de

    1998-01-01

    In this paper the motivation, design and application of a distributed blackboard architecture for interactive data visualization is discussed. The main advantages of the architecture is twofold. First, it allows visualization tools to be tightly integrated with simulations. Second, it allows qualit

  17. Software To Secure Distributed Propulsion Simulations

    Science.gov (United States)

    Blaser, Tammy M.

    2003-01-01

    Distributed-object computing systems are presented with many security threats, including network eavesdropping, message tampering, and communications middleware masquerading. NASA Glenn Research Center, and its industry partners, has taken an active role in mitigating the security threats associated with developing and operating their proprietary aerospace propulsion simulations. In particular, they are developing a collaborative Common Object Request Broker Architecture (CORBA) Security (CORBASec) test bed to secure their distributed aerospace propulsion simulations. Glenn has been working with its aerospace propulsion industry partners to deploy the Numerical Propulsion System Simulation (NPSS) object-based technology. NPSS is a program focused on reducing the cost and time in developing aerospace propulsion engines

  18. Object-oriented framework for distributed simulation

    Science.gov (United States)

    Hunter, Julia; Carson, John A.; Colley, Martin; Standeven, John; Callaghan, Victor

    1999-06-01

    The benefits of object-oriented technology are widely recognized in software engineering. This paper describes the use of the object-oriented paradigm to create distributed simulations. The University of Essex Robotics and Intelligent Machines group has been carrying out research into distributed vehicle simulation since 1992. Part of this research has focused on the development of simulation systems to assist in the design of robotic vehicles. This paper describes the evolution of these systems, from an early toolkit used for teaching robotics to recent work on using simulation as a design tool in the creation of a new generation of unmanned underwater vehicles. It outlines experiences gained in using PVM, and ongoing research into the use of the emerging High Level Architecture as the basis for these frameworks. The paper concludes with the perceived benefits of adopting object-oriented methodologies as the basis for simulation frameworks.

  19. Multiple peaks of species abundance distributions induced by sparse interactions

    CERN Document Server

    Obuchi, Tomoyuki; Tokita, Kei

    2016-01-01

    We investigate the replicator dynamics with "sparse" symmetric interactions which represent specialist-specialist interactions in ecological communities. By considering a large self interaction $u$, we conduct a perturbative expansion which manifests that the nature of the interactions has a direct impact on the species abundance distribution. The central results are all species coexistence in a realistic range of the model parameters and that a certain discrete nature of the interactions induces multiple peaks in the species abundance distribution, providing the possibility of theoretically explaining multiple peaks observed in various field studies. To get more quantitative information, we also construct a non-perturbative theory which becomes exact on tree-like networks if all the species coexist, providing exact critical values of $u$ below which extinct species emerge. Numerical simulations in various different situations are conducted and they clarify the robustness of the presented mechanism of all spe...

  20. Multi-threaded, discrete event simulation of distributed computing systems

    Science.gov (United States)

    Legrand, Iosif; MONARC Collaboration

    2001-10-01

    The LHC experiments have envisaged computing systems of unprecedented complexity, for which is necessary to provide a realistic description and modeling of data access patterns, and of many jobs running concurrently on large scale distributed systems and exchanging very large amounts of data. A process oriented approach for discrete event simulation is well suited to describe various activities running concurrently, as well the stochastic arrival patterns specific for such type of simulation. Threaded objects or "Active Objects" can provide a natural way to map the specific behaviour of distributed data processing into the simulation program. The simulation tool developed within MONARC is based on Java (TM) technology which provides adequate tools for developing a flexible and distributed process oriented simulation. Proper graphics tools, and ways to analyze data interactively, are essential in any simulation project. The design elements, status and features of the MONARC simulation tool are presented. The program allows realistic modeling of complex data access patterns by multiple concurrent users in large scale computing systems in a wide range of possible architectures, from centralized to highly distributed. Comparison between queuing theory and realistic client-server measurements is also presented.

  1. Evaluating Australian football league player contributions using interactive network simulation.

    Science.gov (United States)

    Sargent, Jonathan; Bedford, Anthony

    2013-01-01

    This paper focuses on the contribution of Australian Football League (AFL) players to their team's on-field network by simulating player interactions within a chosen team list and estimating the net effect on final score margin. A Visual Basic computer program was written, firstly, to isolate the effective interactions between players from a particular team in all 2011 season matches and, secondly, to generate a symmetric interaction matrix for each match. Negative binomial distributions were fitted to each player pairing in the Geelong Football Club for the 2011 season, enabling an interactive match simulation model given the 22 chosen players. Dynamic player ratings were calculated from the simulated network using eigenvector centrality, a method that recognises and rewards interactions with more prominent players in the team network. The centrality ratings were recorded after every network simulation and then applied in final score margin predictions so that each player's match contribution-and, hence, an optimal team-could be estimated. The paper ultimately demonstrates that the presence of highly rated players, such as Geelong's Jimmy Bartel, provides the most utility within a simulated team network. It is anticipated that these findings will facilitate optimal AFL team selection and player substitutions, which are key areas of interest to coaches. Network simulations are also attractive for use within betting markets, specifically to provide information on the likelihood of a chosen AFL team list "covering the line ". Key pointsA simulated interaction matrix for Australian Rules football players is proposedThe simulations were carried out by fitting unique negative binomial distributions to each player pairing in a sideEigenvector centrality was calculated for each player in a simulated matrix, then for the teamThe team centrality measure adequately predicted the team's winning marginA player's net effect on margin could hence be estimated by replacing him in

  2. Simulation of warehousing and distribution systems

    Directory of Open Access Journals (Sweden)

    Drago Pupavac

    2005-08-01

    Full Text Available The modern world abounds in simulation models. Thousands of organizations use simulation models to solve business problems. Problems in micro logistics systems are a very important segment of the business problems that can be solved by a simulation method. In most cases logistics simulation models should be developed with a purpose to evaluate the performance of individual value-adding indirect resources of logistics system, their possibilities and operational advantages as well as the flow of logistics entities between the plants, warehouses, and customers. Accordingly, this scientific paper elaborates concisely the theoretical characteristics of simulation models and the domains in which the simulation approach is best suited in logistics. Special attention is paid to simulation modeling of warehousing and distribution subsystems of logistic system and there is an example of spreadsheet application in the function of simulated demand for goods from warehouse. Apart from simulation model induction and deduction methods, the description method and a method of information modeling are applied.

  3. Interactive Visualization and Simulation of Astronomical Nebulae

    CERN Document Server

    Wenger, Stephan; Steffen, Wolfgang; Koning, Nico; Weiskopf, Daniel; Magnor, Marcus

    2012-01-01

    Interactive visualization and simulation of astrophysical phenomena help astronomers and enable digital planetariums and television documentaries to take their spectators on a journey into deep space to explore the astronomical wonders of our universe in 3D.

  4. Conditional Knowledge as a Basis for Distributed Simulation

    OpenAIRE

    Chandy, K. Mani; Misra, Jay

    1987-01-01

    A goal of this paper is to explore different ways of implementing distributed simulations. Distributed simulation grew out of sequential simulation, and it is possible that the way we think about distributed simulation is unduly influenced by its sequential origins. To free ourselves from unnecessary restrictions on the way we design distributed simulations, in this paper we define the distributed simulation problem somewhat differently than in the literature. We propose the concepts of "know...

  5. Integrating software architectures for distributed simulations and simulation analysis communities.

    Energy Technology Data Exchange (ETDEWEB)

    Goldsby, Michael E.; Fellig, Daniel; Linebarger, John Michael; Moore, Patrick Curtis; Sa, Timothy J.; Hawley, Marilyn F.

    2005-10-01

    The one-year Software Architecture LDRD (No.79819) was a cross-site effort between Sandia California and Sandia New Mexico. The purpose of this research was to further develop and demonstrate integrating software architecture frameworks for distributed simulation and distributed collaboration in the homeland security domain. The integrated frameworks were initially developed through the Weapons of Mass Destruction Decision Analysis Center (WMD-DAC), sited at SNL/CA, and the National Infrastructure Simulation & Analysis Center (NISAC), sited at SNL/NM. The primary deliverable was a demonstration of both a federation of distributed simulations and a federation of distributed collaborative simulation analysis communities in the context of the same integrated scenario, which was the release of smallpox in San Diego, California. To our knowledge this was the first time such a combination of federations under a single scenario has ever been demonstrated. A secondary deliverable was the creation of the standalone GroupMeld{trademark} collaboration client, which uses the GroupMeld{trademark} synchronous collaboration framework. In addition, a small pilot experiment that used both integrating frameworks allowed a greater range of crisis management options to be performed and evaluated than would have been possible without the use of the frameworks.

  6. Exposing Conditional Inclusive Ideologies through Simulated Interactions

    Science.gov (United States)

    Dotger, Benjamin; Ashby, Christine

    2010-01-01

    This manuscript examines how teacher candidates enacted their extensive inclusive classroom preparation within simulated interactions. Diffusing a common medical education pedagogy to teacher education, the researchers situated inclusively-trained teacher candidates in front of standardized paraprofessionals. Data from these simulated interactions…

  7. Salesperson Ethics: An Interactive Computer Simulation

    Science.gov (United States)

    Castleberry, Stephen

    2014-01-01

    A new interactive computer simulation designed to teach sales ethics is described. Simulation learner objectives include gaining a better understanding of legal issues in selling; realizing that ethical dilemmas do arise in selling; realizing the need to be honest when selling; seeing that there are conflicting demands from a salesperson's…

  8. Salesperson Ethics: An Interactive Computer Simulation

    Science.gov (United States)

    Castleberry, Stephen

    2014-01-01

    A new interactive computer simulation designed to teach sales ethics is described. Simulation learner objectives include gaining a better understanding of legal issues in selling; realizing that ethical dilemmas do arise in selling; realizing the need to be honest when selling; seeing that there are conflicting demands from a salesperson's…

  9. Toward an Ontology of Simulated Social Interaction

    DEFF Research Database (Denmark)

    2016-01-01

    The paper develops a general conceptual framework for the ontological classification of human-robot interaction. After arguing against fictionalist interpretations of human-robot interactions, I present five notions of simulation or partial realization, formally defined in terms of relationships...

  10. Research on HLA Distributing Interactive Simulation of Torpedo Weapon System%基于HLA的鱼雷武器系统分布交互仿真

    Institute of Scientific and Technical Information of China (English)

    魏静; 高立娥; 杜来毅; 王飞

    2011-01-01

    为避免传统意义上低层次、低效率的重复开发,通过对HIA联邦成员的仿真流程及内部接口关系的研究,构建了基于HLA标准的由鱼雷、发射艇、目标、对抗器材等联邦成员组成的鱼雷作战对抗分布交互仿真系统,给出了仿真系统的网络拓扑结构,完成了联邦成员的功能实现.介绍了水声对抗条件下的基本作战仿真流程,包括初始设定、仿真计算、搜索探测、决策方案、双方武器或干扰器材的对抗过程、仿真结束等六个阶段:完成了鱼雷武器系统在潜一潜,舰一潜对抗态势条件下的弹道仿真研究.%In order to ovoid low level and inefficient exploitation , by means of researching of simulation flow and inside interface of HLA federation member, based on HLA standard, torpedo warfare simulation system is established by federation members such as torpedo, launch ship, target and confront equipments.This paper introduces the principal campaign simulation flow under the different countermove.It consists of the initialization, searching, detecting, decision, and the countermine process for weapon and countermeasure, and it investigates the ballistic trajectory simulation under the submarine to submarine countermine situation.

  11. EVALUATING AUSTRALIAN FOOTBALL LEAGUE PLAYER CONTRIBUTIONS USING INTERACTIVE NETWORK SIMULATION

    Directory of Open Access Journals (Sweden)

    Jonathan Sargent

    2013-03-01

    Full Text Available This paper focuses on the contribution of Australian Football League (AFL players to their team's on-field network by simulating player interactions within a chosen team list and estimating the net effect on final score margin. A Visual Basic computer program was written, firstly, to isolate the effective interactions between players from a particular team in all 2011 season matches and, secondly, to generate a symmetric interaction matrix for each match. Negative binomial distributions were fitted to each player pairing in the Geelong Football Club for the 2011 season, enabling an interactive match simulation model given the 22 chosen players. Dynamic player ratings were calculated from the simulated network using eigenvector centrality, a method that recognises and rewards interactions with more prominent players in the team network. The centrality ratings were recorded after every network simulation and then applied in final score margin predictions so that each player's match contribution-and, hence, an optimal team-could be estimated. The paper ultimately demonstrates that the presence of highly rated players, such as Geelong's Jimmy Bartel, provides the most utility within a simulated team network. It is anticipated that these findings will facilitate optimal AFL team selection and player substitutions, which are key areas of interest to coaches. Network simulations are also attractive for use within betting markets, specifically to provide information on the likelihood of a chosen AFL team list "covering the line".

  12. A Modular Toolkit for Distributed Interactions

    Directory of Open Access Journals (Sweden)

    Julien Lange

    2011-10-01

    Full Text Available We discuss the design, architecture, and implementation of a toolkit which supports some theories for distributed interactions. The main design principles of our architecture are flexibility and modularity. Our main goal is to provide an easily extensible workbench to encompass current algorithms and incorporate future developments of the theories. With the help of some examples, we illustrate the main features of our toolkit.

  13. Simulation of wave interactions with MHD

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, D; Bernholdt, D; Berry, L; Elwasif, W; Jaeger, E; Keyes, D; Klasky, S [Oak Ridge National Laboratory, Oak Ridge, TN 37331 (United States); Alba, C; Choi, M [General Atomics, San Diego, CA 92186 (United States); Bateman, G [Lehigh University, Bethlehem, PA 18015 (United States); Bonoli, P [Plasma Science and Fusion Center, MTT, Cambridge, MA 02139 (United States); Bramley, R [Indiana University, Bloomington, IN 47405 (United States); Breslau, J; Chance, M; Chen, J; Fu, G; Jardin, S [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Harvey, R [CompX, Del Mar, CA 92014 (United States); Jenkins, T [University of Wisconsin, Madison, WI 53706 (United States); Kruger, S [Tech-X, Boulder, CO 80303 (United States)], E-mail: batchelordb@ornl.gov (and others)

    2008-07-15

    The broad scientific objectives of the SWIM (Simulation 01 Wave Interaction with MHD) project are twofold: (1) improve our understanding of interactions that both radio frequency (RF) wave and particle sources have on extended-MHD phenomena, and to substantially improve our capability for predicting and optimizing the performance of burning plasmas in devices such as ITER: and (2) develop an integrated computational system for treating multiphysics phenomena with the required flexibility and extensibility to serve as a prototype for the Fusion Simulation Project. The Integrated Plasma Simulator (IPS) has been implemented. Presented here are initial physics results on RP effects on MHD instabilities in tokamaks as well as simulation results for tokamak discharge evolution using the IPS.

  14. Simulation of wave interactions with MHD

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, Donald B [ORNL; Abla, G [General Atomics, San Diego; Bateman, Glenn [Lehigh University, Bethlehem, PA; Bernholdt, David E [ORNL; Berry, Lee A [ORNL; Bonoli, P. [Massachusetts Institute of Technology (MIT); Bramley, R [Indiana University; Breslau, J. [Princeton Plasma Physics Laboratory (PPPL); Chance, M. [Princeton Plasma Physics Laboratory (PPPL); Chen, J. [Princeton Plasma Physics Laboratory (PPPL); Choi, M. [General Atomics; Elwasif, Wael R [ORNL; Fu, GuoYong [Princeton Plasma Physics Laboratory (PPPL); Harvey, R. W. [CompX, Del Mar, CA; Jaeger, Erwin Frederick [ORNL; Jardin, S. C. [Princeton Plasma Physics Laboratory (PPPL); Jenkins, T [University of Wisconsin; Keyes, David E [Columbia University; Klasky, Scott A [ORNL; Kruger, Scott [Tech-X Corporation; Ku, Long-Poe [Princeton Plasma Physics Laboratory (PPPL); Lynch, Vickie E [ORNL; McCune, Douglas [Princeton Plasma Physics Laboratory (PPPL); Ramos, J. [Massachusetts Institute of Technology (MIT); Schissel, D. [General Atomics; Schnack, [University of Wisconsin; Wright, J. [Massachusetts Institute of Technology (MIT)

    2008-07-01

    The broad scientific objectives of the SWIM (Simulation of Wave Interaction with MHD) project are twofold: (1) improve our understanding of interactions that both radio frequency (RF) wave and particle sources have on extended-MHD phenomena, and to substantially improve our capability for predicting and optimizing the performance of burning plasmas in devices such as ITER: and (2) develop an integrated computational system for treating multiphysics phenomena with the required flexibility and extensibility to serve as a prototype for the Fusion Simulation Project. The Integrated Plasma Simulator (IPS) has been implemented. Presented here are initial physics results on RF effects on MHD instabilities in tokamaks as well as simulation results for tokamak discharge evolution using the IPS.

  15. Equilibrium distribution from distributed computing (simulations of protein folding).

    Science.gov (United States)

    Scalco, Riccardo; Caflisch, Amedeo

    2011-05-19

    Multiple independent molecular dynamics (MD) simulations are often carried out starting from a single protein structure or a set of conformations that do not correspond to a thermodynamic ensemble. Therefore, a significant statistical bias is usually present in the Markov state model generated by simply combining the whole MD sampling into a network whose nodes and links are clusters of snapshots and transitions between them, respectively. Here, we introduce a depth-first search algorithm to extract from the whole conformation space network the largest ergodic component, i.e., the subset of nodes of the network whose transition matrix corresponds to an ergodic Markov chain. For multiple short MD simulations of a globular protein (as in distributed computing), the steady state, i.e., stationary distribution determined using the largest ergodic component, yields more accurate free energy profiles and mean first passage times than the original network or the ergodic network obtained by imposing detailed balance by means of symmetrization of the transition counts.

  16. Interactive Heat Transfer Simulations for Everyone

    Science.gov (United States)

    Xie, Charles

    2012-01-01

    Heat transfer is widely taught in secondary Earth science and physics. Researchers have identified many misconceptions related to heat and temperature. These misconceptions primarily stem from hunches developed in everyday life (though the confusions in terminology often worsen them). Interactive computer simulations that visualize thermal energy,…

  17. Interactive Mathematica Simulations in Chemical Engineering Courses

    Science.gov (United States)

    Falconer, John L.; Nicodemus, Garret D.

    2014-01-01

    Interactive Mathematica simulations with graphical displays of system behavior are an excellent addition to chemical engineering courses. The Manipulate command in Mathematica creates on-screen controls that allow users to change system variables and see the graphical output almost instantaneously. They can be used both in and outside class. More…

  18. Interactive Mathematica Simulations in Chemical Engineering Courses

    Science.gov (United States)

    Falconer, John L.; Nicodemus, Garret D.

    2014-01-01

    Interactive Mathematica simulations with graphical displays of system behavior are an excellent addition to chemical engineering courses. The Manipulate command in Mathematica creates on-screen controls that allow users to change system variables and see the graphical output almost instantaneously. They can be used both in and outside class. More…

  19. Interactive Heat Transfer Simulations for Everyone

    Science.gov (United States)

    Xie, Charles

    2012-01-01

    Heat transfer is widely taught in secondary Earth science and physics. Researchers have identified many misconceptions related to heat and temperature. These misconceptions primarily stem from hunches developed in everyday life (though the confusions in terminology often worsen them). Interactive computer simulations that visualize thermal energy,…

  20. Interactive visualization to advance earthquake simulation

    Science.gov (United States)

    Kellogg, L.H.; Bawden, G.W.; Bernardin, T.; Billen, M.; Cowgill, E.; Hamann, B.; Jadamec, M.; Kreylos, O.; Staadt, O.; Sumner, D.

    2008-01-01

    The geological sciences are challenged to manage and interpret increasing volumes of data as observations and simulations increase in size and complexity. For example, simulations of earthquake-related processes typically generate complex, time-varying data sets in two or more dimensions. To facilitate interpretation and analysis of these data sets, evaluate the underlying models, and to drive future calculations, we have developed methods of interactive visualization with a special focus on using immersive virtual reality (VR) environments to interact with models of Earth's surface and interior. Virtual mapping tools allow virtual "field studies" in inaccessible regions. Interactive tools allow us to manipulate shapes in order to construct models of geological features for geodynamic models, while feature extraction tools support quantitative measurement of structures that emerge from numerical simulation or field observations, thereby enabling us to improve our interpretation of the dynamical processes that drive earthquakes. VR has traditionally been used primarily as a presentation tool, albeit with active navigation through data. Reaping the full intellectual benefits of immersive VR as a tool for scientific analysis requires building on the method's strengths, that is, using both 3D perception and interaction with observed or simulated data. This approach also takes advantage of the specialized skills of geological scientists who are trained to interpret, the often limited, geological and geophysical data available from field observations. ?? Birkhaueser 2008.

  1. Distributed communication and psychosocial performance in simulated space dwelling groups

    Science.gov (United States)

    Hienz, R. D.; Brady, J. V.; Hursh, S. R.; Ragusa, L. C.; Rouse, C. O.; Gasior, E. D.

    2005-05-01

    The present report describes the development and application of a distributed interactive multi-person simulation in a computer-generated planetary environment as an experimental test bed for modeling the human performance effects of variations in the types of communication modes available, and in the types of stress and incentive conditions underlying the completion of mission goals. The results demonstrated a high degree of interchangeability between communication modes (audio, text) when one mode was not available. Additionally, the addition of time pressure stress to complete tasks resulted in a reduction in performance effectiveness, and these performance reductions were ameliorated via the introduction of positive incentives contingent upon improved performances. The results obtained confirmed that cooperative and productive psychosocial interactions can be maintained between individually isolated and dispersed members of simulated spaceflight crews communicating and problem-solving effectively over extended time intervals without the benefit of one another's physical presence.

  2. Reactive Control of Distributed Interactive Simulations

    Science.gov (United States)

    2007-11-02

    San Deigo, CA. [50] Kohn, W. and T. Skillman , "Hierarchical Control Systems for Autonomous Space Robots," Proceedings of AIAA Conference in...1988. [60] Robinson, J.A., Logic: Form and Function, North Holland, NY, 1979. [61] Skillman , T. and Kohn, W., et.al., "Class of Hierarchical

  3. Interacting discrete Markov processes with power-law probability distributions

    Science.gov (United States)

    Ridley, Kevin D.; Jakeman, Eric

    2017-09-01

    During recent years there has been growing interest in the occurrence of long-tailed distributions, also known as heavy-tailed or fat-tailed distributions, which can exhibit power-law behaviour and often characterise physical systems that undergo very large fluctuations. In this paper we show that the interaction between two discrete Markov processes naturally generates a time-series characterised by such a distribution. This possibility is first demonstrated by numerical simulation and then confirmed by a mathematical analysis that enables the parameter range over which the power-law occurs to be quantified. The results are supported by comparison of numerical results with theoretical predictions and general conclusions are drawn regarding mechanisms that can cause this behaviour.

  4. Pseudo-interactive monitoring in distributed computing

    Energy Technology Data Exchange (ETDEWEB)

    Sfiligoi, I.; /Fermilab; Bradley, D.; Livny, M.; /Wisconsin U., Madison

    2009-05-01

    Distributed computing, and in particular Grid computing, enables physicists to use thousands of CPU days worth of computing every day, by submitting thousands of compute jobs. Unfortunately, a small fraction of such jobs regularly fail; the reasons vary from disk and network problems to bugs in the user code. A subset of these failures result in jobs being stuck for long periods of time. In order to debug such failures, interactive monitoring is highly desirable; users need to browse through the job log files and check the status of the running processes. Batch systems typically don't provide such services; at best, users get job logs at job termination, and even this may not be possible if the job is stuck in an infinite loop. In this paper we present a novel approach of using regular batch system capabilities of Condor to enable users to access the logs and processes of any running job. This does not provide true interactive access, so commands like vi are not viable, but it does allow operations like ls, cat, top, ps, lsof, netstat and dumping the stack of any process owned by the user; we call this pseudo-interactive monitoring. It is worth noting that the same method can be used to monitor Grid jobs in a glidein-based environment. We further believe that the same mechanism could be applied to many other batch systems.

  5. Distributed Power-Flow Controller (DPFC Simulation

    Directory of Open Access Journals (Sweden)

    T Jagan Mohan Rao

    2014-10-01

    Full Text Available This paper describes the steady-state response and control of power in transmission line equipped with FACTS devices. Detailed simulations are carried out on two -machine systems to illustrate the control features of these devices and their influence to increase power transfer capability and improve system reliability. The DPFC is derived from the unified power-flow controller (UPFC and DPFC has the same control capability as the UPFC. The DPFC can be considered as a UPFC with an eliminated common dc link. The active power exchange between the shunt and series converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third -harmonic frequency. The interaction between the DPFC, the network and the machines are analyzed.

  6. Hybrid Simulations of Pluto's Plasma Interaction

    Science.gov (United States)

    Feyerabend, M.; Simon, S.; Motschmann, U.; Liuzzo, L.

    2016-12-01

    We study the interaction between Pluto and the solar wind at the time of the New Horizons (NH) flyby by applying a hybrid (kinetic ions, fluid electrons) simulation model. The use of a hybrid model is necessary since the gyroradii of the involved ion species are more than an order of magnitude larger than the obstacle to the solar wind and thus, Pluto's interaction region displays considerable asymmetries. We investigate the three-dimensional structure and extension of the various plasma signatures seen along the NH trajectory. Especially, we will constrain possible asymmetries in the shape of Pluto's bow shock, plasma tail and Plutopause (i.e., the boundary between the solar wind and the population of plutogenic ions) which may arise from the large ion gyroradii. Starting from the upstream solar wind parameters measured by NH, we investigate the dependency of these plasma signatures on the density of Pluto's ionosphere and on the solar wind ram pressure. We also include Pluto's largest moon Charon into the simulation model and study the simultaneous interaction between both bodies and the solar wind. Data from NH suggest that Charon mainly acts as a plasma absorber without an appreciable atmosphere. For various relative positions of Pluto and Charon, we investigate the deformation of Charon's wake when exposed to the inhomogeneous plasma flow in the Pluto interaction region, as well as a possible feedback of Charon on the structure of Pluto's induced magnetosphere.

  7. SimpLens: Interactive gravitational lensing simulator

    Science.gov (United States)

    Saha, Prasenjit; Williams, Liliya L. R.

    2016-06-01

    SimpLens illustrates some of the theoretical ideas important in gravitational lensing in an interactive way. After setting parameters for elliptical mass distribution and external mass, SimpLens displays the mass profile and source position, the lens potential and image locations, and indicate the image magnifications and contours of virtual light-travel time. A lens profile can be made shallower or steeper with little change in the image positions and with only total magnification affected.

  8. Distribution of Steps with Finite-Range Interactions: Analytic Approximations and Numerical Results

    Science.gov (United States)

    GonzáLez, Diego Luis; Jaramillo, Diego Felipe; TéLlez, Gabriel; Einstein, T. L.

    2013-03-01

    While most Monte Carlo simulations assume only nearest-neighbor steps interact elastically, most analytic frameworks (especially the generalized Wigner distribution) posit that each step elastically repels all others. In addition to the elastic repulsions, we allow for possible surface-state-mediated interactions. We investigate analytically and numerically how next-nearest neighbor (NNN) interactions and, more generally, interactions out to q'th nearest neighbor alter the form of the terrace-width distribution and of pair correlation functions (i.e. the sum over n'th neighbor distribution functions, which we investigated recently.[2] For physically plausible interactions, we find modest changes when NNN interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms.

  9. PLEVIS (Plant Engineering Visual and Interactive Simulator), a plant engineering visual and interactive simulator

    Energy Technology Data Exchange (ETDEWEB)

    Mizukami, Masumi; Yoshikawa, Eiji; Tanaka, Kazuma; Otsuka, Shiro

    1989-01-01

    Toshiba and Nippon Atomic Industry Group Company (NAIG) have devoted much effort to the development of nuclear power simulators for operator training, such as replica simulators and compact simulators since 1973. These simulators have special-purpose consoles or control room equipment for operation training and run on one or more process computers; therefore, they require a large amount of space, e.g., a special room for installation. The Plant Engineering Visual and Interactive Simulator (PLEVIS) is a real-time plant engineering simulator and operates on a general-purpose desk-side engineering workstation (Sun4 series) with a high-resolution bit-mapped display. The major objectives of PLEVIS are to further improve training performance and efficiency, not only for operators, but also for engineers, and to provide a powerful and cost-effective plant engineering tool. The PELVIS development objectives and background technologies are shown. System configuration and major features are discussed.

  10. Local simulation algorithms for Coulombic interactions

    Indian Academy of Sciences (India)

    L Leverel; F Alet; J Rottler; A C Maggs

    2005-06-01

    We consider a problem in dynamically constrained Monte Carlo dynamics and show that this leads to the generation of long ranged effective interactions. This allows us to construct a local algorithm for the simulation of charged systems without ever having to evaluate pair potentials or solve the Poisson equation. We discuss a simple implementation of a charged lattice gas as well as more elaborate off-lattice versions of the algorithm. There are analogies between our formulation of electrostatics and the bosonic Hubbard model in the phase approximation. Cluster methods developed for this model further improve the efficiency of the electrostatics algorithm.

  11. Tornado structure interaction: a numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T.

    1977-05-20

    The effects of tornadoes on buildings are examined to determine the wind forces on structures. The American National Standards Institute (ANSI) has developed guidelines for building code requirements for the minimum wind loads a building must be designed to withstand. The conservatism or nonconservatism on the ANSI approach is evaluated by simulating tornado-structure interaction numerically with a two-dimensional fluid dynamics computer code and a vortex model. Only external pressures are considered. The computer calculations yield the following percentages of the ANSI design pressures: rigid frame, 50 to 90%; individual wall panels, 75 to 200%; and wall corners, 50 to 75%.

  12. Derivation of Distributed Models of Atomic Polarizability for Molecular Simulations.

    Science.gov (United States)

    Soteras, Ignacio; Curutchet, Carles; Bidon-Chanal, Axel; Dehez, François; Ángyán, János G; Orozco, Modesto; Chipot, Christophe; Luque, F Javier

    2007-11-01

    The main thrust of this investigation is the development of models of distributed atomic polarizabilities for the treatment of induction effects in molecular mechanics simulations. The models are obtained within the framework of the induced dipole theory by fitting the induction energies computed via a fast but accurate MP2/Sadlej-adjusted perturbational approach in a grid of points surrounding the molecule. Particular care is paid in the examination of the atomic quantities obtained from models of implicitly and explicitly interacting polarizabilities. Appropriateness and accuracy of the distributed models are assessed by comparing the molecular polarizabilities recovered from the models and those obtained experimentally and from MP2/Sadlej calculations. The behavior of the models is further explored by computing the polarization energy for aromatic compounds in the context of cation-π interactions and for selected neutral compounds in a TIP3P aqueous environment. The present results suggest that the computational strategy described here constitutes a very effective tool for the development of distributed models of atomic polarizabilities and can be used in the generation of new polarizable force fields.

  13. Monitoring and Steering of Large-Scale Distributed Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Geist, G.A.; Kohl, J.A.

    1999-09-01

    Oak Ridge National Laboratory is developing a state-of-the-art parallel application development system called CUMULVS, which allows scientists to easily incorporate interactive visualization, computational steering and fault tolerance into distributed software applications. The system is a valuable tool for many large scientific applications because it enables the scientist to visually monitor large data fields and remotely control parameters inside a running application. Collaborative monitoring is provided by allowing multiple researchers to simultaneously attach to a simulation, each controlling their own view of the same or different data fields within the simulation. By supporting steering of a simulation while it is running, CUMULVS provides the opportunity to accelerate the process of scientific discovery. CUMULVS also provides a simple mechanism to incorporate automatic checkpointing and heterogeneous task migration into large applications so that simulations can continue to run for weeks unattended. This paper will give an overview of the CUMULVS system and its capabilities, including several case histories. The status of the project is described with instructions on how to obtain the software.

  14. Interactive simulations as teaching tools for engineering mechanics courses

    Science.gov (United States)

    Carbonell, Victoria; Romero, Carlos; Martínez, Elvira; Flórez, Mercedes

    2013-07-01

    This study aimed to gauge the effect of interactive simulations in class as an active teaching strategy for a mechanics course. Engineering analysis and design often use the properties of planar sections in calculations. In the stress analysis of a beam under bending and torsional loads, cross-sectional properties are used to determine stress and displacement distributions in the beam cross section. The centroid, moments and products of inertia of an area made up of several common shapes (rectangles usually) may thus be obtained by adding the moments of inertia of the component areas (U-shape, L-shape, C-shape, etc). This procedure is used to calculate the second moments of structural shapes in engineering practice because the determination of their moments of inertia is necessary for the design of structural components. This paper presents examples of interactive simulations developed for teaching the ‘Mechanics and mechanisms’ course at the Universidad Politecnica de Madrid, Spain. The simulations focus on fundamental topics such as centroids, the properties of the moment of inertia, second moments of inertia with respect to two axes, principal moments of inertia and Mohr's Circle for plane stress, and were composed using Geogebra software. These learning tools feature animations, graphics and interactivity and were designed to encourage student participation and engagement in active learning activities, to effectively explain and illustrate course topics, and to build student problem-solving skills.

  15. Simulations of flow interactions near Los Alamos

    Energy Technology Data Exchange (ETDEWEB)

    Costigan, K. R. (Keeley R.); Winterkamp, Judy; Bossert, J. E. (James E.); Langley, D. L. (David L.)

    2002-01-01

    The Pajarito Plateau is located on the eastern flank of the Jemez Mountains and the west side of the Rio Grande Valley, in north-central New Mexico, where the river runs roughly north to south. On the Pajarito Plateau, a network of surface meteorological stations has been routinely maintained by Los Alamos National Laboratory. This network includes five instrumented towers, within an approximately 10 km by 15 km area. The towers stand from 23 m to 92 m tall, with multiple wind measurement heights. Investigation of the station records indicates that the wind fields can be quite complicated and may be the result of interactions of thermally and/or dynamically driven flows of many scales. Slope flows are often found on the plateau during the morning and evening transition times, but it is not unusual to find wind directions that are inconsistent with slope flows at some or all of the stations. It has been speculated that valley circulations, as well as synoptically driven winds, interact with the slope flows, but the mesonet measurements alone, with no measurements in the remainder of the valley, were not sufficient to investigate this hypothesis. Thus, during October of 1995, supplemental meteorological instrumentation was placed in the Rio Grande basin to study the complex interaction of flows in the area. A sodar was added near the 92 m tower and a radar wind profiler was placed in the Rio Grande Valley, just east of the plateau and near the river. Measurements were also added at the top of Pajarito Mountain, just west of the plateau, and across the valley, to the east, on top of Tesuque Peak (in the Sangre de Cristo Mountains). Two surface stations were also added to the north-facing slopes of Pajarito Mountain. This paper will present observations from October 1995 and results of simulations of this area that are used in the study of the complex interaction of dynamically and thermally driven flows on multiple scales.

  16. Computer simulation of spacecraft/environment interaction.

    Science.gov (United States)

    Krupnikov, K K; Makletsov, A A; Mileev, V N; Novikov, L S; Sinolits, V V

    1999-10-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991 1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.

  17. Computer simulation of spacecraft/environment interaction

    CERN Document Server

    Krupnikov, K K; Mileev, V N; Novikov, L S; Sinolits, V V

    1999-01-01

    This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991-1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.

  18. Simulated Mima mounds emerge from small interactions

    CERN Document Server

    Lewis, Chloë Peregrine Hunt

    2011-01-01

    The Mima-mound-and-vernal-pool topography of California is rich in endemic plant and invertebrate species, but we do not know how this unusual environment is created or maintained. Burrowing rodents have been observed to move soil upwards at annual rates sufficient to maintain the mounds despite erosion, but there is no tested explanation of this behavior. We propose that the mounds are an emergent effect of small-scale (10 cm, 1 day) interactions between topography, hydrology, plant growth, and rodent burrowing. A cellular automata simulation of these processes both generates and maintains mound-pool topography with minimal dependence on initial conditions, and can also describe mound morphogenesis on slopes, where observed mound geometry is distinct from that on level ground.

  19. An Educational Tool for Interactive Parallel and Distributed Processing

    DEFF Research Database (Denmark)

    Pagliarini, Luigi; Lund, Henrik Hautop

    2011-01-01

    In this paper we try to describe how the Modular Interactive Tiles System (MITS) can be a valuable tool for introducing students to interactive parallel and distributed processing programming. This is done by providing an educational hands-on tool that allows a change of representation...... of the abstract problems related to designing interactive parallel and distributed systems. Indeed, MITS seems to bring a series of goals into the education, such as parallel programming, distributedness, communication protocols, master dependency, software behavioral models, adaptive interactivity, feedback...... parallel and distributed processing with different software behavioural models such as open loop, randomness based, rule based, user interaction based, AI and ALife based software....

  20. AISIM (Automated Interactive Simulation Modeling System) VAX Version Training Manual.

    Science.gov (United States)

    1985-02-01

    AD-Ri6t 436 AISIM (RUTOMATED INTERACTIVE SIMULATION MODELING 1/2 SYSTEM) VAX VERSION TRAI (U) HUGHES AIRCRAFT CO FULLERTON CA GROUND SYSTEMS GROUP S...Continue on reverse if necessary and Identify by block number) THIS DOCUMENT IS THE TRAINING MANUAL FOR THE AUTOMATED INTERACTIVE SIMULATION MODELING SYSTEM...form. Page 85 . . . . . . . . APPENDIX B SIMULATION REPORT FOR WORKING EXAMPLE Pa jPage.8 7AD-Ai6i 46 ISIM (AUTOMATED INTERACTIVE SIMULATION MODELING 2

  1. Numerical Simulations of Disk-Planet Interactions

    Science.gov (United States)

    D'Angelo, Gennaro

    2003-06-01

    The aim of this thesis is the study the dynamical interactions occurring between a forming planet and its surrounding protostellar environment. This task is accomplished by means of both 2D and 3D numerical simulations. The first part of this work concerned global simulations in 3D. These were intended to investigate large-scale effects caused by a Jupiter-size body still in the process of accreting matter from its surroundings. Simulations show that, despite a density gap forms along the orbital path, Jupiter-mass protoplanets still accrete at a rate on the order of 0.01 Earth's masses per year when they are embedded in a minimum-mass Solar nebula. In the same conditions, the migration time scale due to gravitational torques by the disk is around 100000 years. The second part of the work was dedicated to perform 2D calculations, by employing a nested-grid technique. This method allows to carry out global simulations of planets orbiting in disks and, at the same time, to resolve in great detail the dynamics of the flow inside the Roche lobe of both massive and low-mass planets. Regardless of the planet mass, the high resolution supplied by the nested-grid technique permits an evaluation of the torques, resulting from short and very short range gravitational interactions, more reliable than the one previously estimated with the aid of numerical methods. Likewise, the mass flow onto the planet is computed in a more accurate fashion. Resulting migration time scales are in the range from 20000 years, for intermediate-mass planets, to 1000000 years, for very low-mass as well as high-mass planets. Circumplanetary disks form inside of the Roche lobe of Jupiter-size secondaries. In order to evaluate the consequences of the flat geometry on the local flow structure around planets, 3D nested-grid simulations were carried out to investigate a range of planetary masses spanning from 1.5 Earth's masses to one Jupiter's mass. Outcomes show that migration rates are relatively

  2. Implementation of force distribution analysis for molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Seifert Christian

    2011-04-01

    Full Text Available Abstract Background The way mechanical stress is distributed inside and propagated by proteins and other biopolymers largely defines their function. Yet, determining the network of interactions propagating internal strain remains a challenge for both, experiment and theory. Based on molecular dynamics simulations, we developed force distribution analysis (FDA, a method that allows visualizing strain propagation in macromolecules. Results To be immediately applicable to a wide range of systems, FDA was implemented as an extension to Gromacs, a commonly used package for molecular simulations. The FDA code comes with an easy-to-use command line interface and can directly be applied to every system built using Gromacs. We provide an additional R-package providing functions for advanced statistical analysis and presentation of the FDA data. Conclusions Using FDA, we were able to explain the origin of mechanical robustness in immunoglobulin domains and silk fibers. By elucidating propagation of internal strain upon ligand binding, we previously also successfully revealed the functionality of a stiff allosteric protein. FDA thus has the potential to be a valuable tool in the investigation and rational design of mechanical properties in proteins and nano-materials.

  3. Runtime Execution Management of Distributed Simulations

    Science.gov (United States)

    2013-12-01

    Gaughan 2011). The EASE architecture consists of a number of components. The Software Design Description ( SDD ) captures the systems engineering...interoperate in a simulation environment. The SDD also allows the system engi- neering user to add new simulation applications (Beauchat et al. 2012). The EASE

  4. Execution Management Solutions for Geographically Distributed Simulations

    NARCIS (Netherlands)

    Berg, T.W. van den; Jansen, H.G.M.; Jansen, R.E.J.; Prins, L.M.

    2009-01-01

    Managing the initialization, execution control and monitoring of HLA federates is not always straightforward, especially for a geographically distributed time managed federation. Issues include pre and post run-time data distribution and run-time data collection; starting, stopping and monitoring

  5. Multivariate stochastic simulation with subjective multivariate normal distributions

    Science.gov (United States)

    P. J. Ince; J. Buongiorno

    1991-01-01

    In many applications of Monte Carlo simulation in forestry or forest products, it may be known that some variables are correlated. However, for simplicity, in most simulations it has been assumed that random variables are independently distributed. This report describes an alternative Monte Carlo simulation technique for subjectively assesed multivariate normal...

  6. A Simulation Model for Evaluating Distributed Systems Dependability

    CERN Document Server

    Dobre, Ciprian; Cristea, Valentin

    2012-01-01

    In this paper we present a new simulation model designed to evaluate the dependability in distributed systems. This model extends the MONARC simulation model with new capabilities for capturing reliability, safety, availability, security, and maintainability requirements. The model has been implemented as an extension of the multithreaded, process oriented simulator MONARC, which allows the realistic simulation of a wide-range of distributed system technologies, with respect to their specific components and characteristics. The extended simulation model includes the necessary components to inject various failure events, and provides the mechanisms to evaluate different strategies for replication, redundancy procedures, and security enforcement mechanisms, as well. The results obtained in simulation experiments presented in this paper probe that the use of discrete-event simulators, such as MONARC, in the design and development of distributed systems is appealing due to their efficiency and scalability.

  7. Simulation of the interaction of tsunami waves with underwater barriers

    Science.gov (United States)

    Boshenyatov, B. V.; Zhiltsov, K. N.

    2016-10-01

    This article examines the experimental and numerical simulation of the processes of distribution and interaction of tsunami-type gravitational waves with one barrier and a complex of two barriers. Experiments were conducted in a hydrodynamic channel using high-precision sensors for the measurement of the wave processes. Mathematical modelling was carried out using two-dimensional non-stationary Navier-Stokes equations for an incompressible fluid using the freely available software package OpenFOAM. It is shown that for small-amplitude waves, when their advance speed is described by the linear theory of shallow water, the interaction with the underwater barriers has important non-linear and viscous effects. Our results explain why a complex of two barriers spaced at a definite distance from each other has a significant impact on the power of the transmitted wave. The energy of the waves passing through the two barriers can be reduced to 35% of the incident wave.

  8. Beam distribution reconstruction simulation for electron beam probe

    CERN Document Server

    Feng, Yongchun; Li, Peng; Kang, Xincai; Yin, Yan; Liu, Tong; You, Yaoyao; Chen, Yucong; Zhao, Tiecheng; Xu, Zhiguo; Wang, Yanyu; Yuan, Youjin

    2016-01-01

    Electron beam probe (EBP) is a new principle detector, which makes use of a low-intensity and low-energy electron beam to measure the transverse profile, bunch shape, beam neutralization and beam wake field of an intense beam with small dimensions. While can be applied to many aspects, we limit our analysis to beam distribution reconstruction. This kind of detector is almost non-interceptive for all of the beam and does not disturb the machine environment. In this paper, we present the theoretical aspects behind this technique for beam distribution measurement and some simulation results of the detector involved. First, a method to obtain parallel electron beam is introduced and a simulation code is developed. And then, EBP as a profile monitor for dense beam is simulated using fast scan method under various target beam profile, such as KV distribution, waterbag distribution, parabolic distribution, Gaussian distribution and halo distribution. Profile reconstruction from the deflected electron beam trajectory...

  9. Effects of biotic interactions on modeled species' distribution can be masked by environmental gradients.

    Science.gov (United States)

    Godsoe, William; Franklin, Janet; Blanchet, F Guillaume

    2017-01-01

    A fundamental goal of ecology is to understand the determinants of species' distributions (i.e., the set of locations where a species is present). Competition among species (i.e., interactions among species that harms each of the species involved) is common in nature and it would be tremendously useful to quantify its effects on species' distributions. An approach to studying the large-scale effects of competition or other biotic interactions is to fit species' distributions models (SDMs) and assess the effect of competitors on the distribution and abundance of the species of interest. It is often difficult to validate the accuracy of this approach with available data. Here, we simulate virtual species that experience competition. In these simulated datasets, we can unambiguously identify the effects that competition has on a species' distribution. We then fit SDMs to the simulated datasets and test whether we can use the outputs of the SDMs to infer the true effect of competition in each simulated dataset. In our simulations, the abiotic environment influenced the effects of competition. Thus, our SDMs often inferred that the abiotic environment was a strong predictor of species abundance, even when the species' distribution was strongly affected by competition. The severity of this problem depended on whether the competitor excluded the focal species from highly suitable sites or marginally suitable sites. Our results highlight how correlations between biotic interactions and the abiotic environment make it difficult to infer the effects of competition using SDMs.

  10. Schedule Risk Analysis Simulator using Beta Distribution

    Directory of Open Access Journals (Sweden)

    Isha Sharma,

    2011-06-01

    Full Text Available This paper describes an application of simulation and Modelling in Software risk management. This paper describes a simulation based software risk management tool which helps manager to identifyhigh risk areas of software process. In this paper an endeavour has been made to build up a Stochastic Simulator which helps in decision making to identify the critical activities which are given due priorities during the development of Software Project. In response to new information or revised estimates, it may be necessary to reassign resources, cancel optional tasks, etc. Project management tools that make projections while treating decisions about tasks and resource assignments as static will not yield realistic results. The usual PERT procedure may lead to overly optimistic results as many pass which are not critical but slightly shorter than critical on the basis of estimated activity duration or average durations.Due to randomness of durations, these pass under some combination of activity durations, could become longer than the average longest path. Such paths would be ignored while using the PERT technique onthe basis of the average durations. In order to overcome this problem and be more reasonable, the said Stochastic Simulator has been designed by generating random samples from a specific probabilitydistribution associated with that particular activity of SPM. The said simulator is also not bugged with overly estimated results.

  11. Effect of intergranular interactions on thermal energy barrier distribution in perpendicular media

    Science.gov (United States)

    Zhou, Hong; Bertram, H. Neal; Schabes, Manfred E.

    2002-05-01

    Micromagnetic simulations have been performed to simulate dynamic hysteresis loops in perpendicular media. Thermal energy barrier distributions have been calculated. For a fixed percentage of magnetization switched, a linear variation between the scaled applied field Ha(t)/HK and ln(f0t)1/2 is found. Without including intergranular magnetostatic interactions, intergranular exchange coupling reduces the thermal energy barrier distribution width, compared to the physical volume distribution width. However, the magnetostatic interactions increase the energy barrier width substantially. The increase is significantly reduced at smaller magnetostatic interactions. For the effective volume of 50% magnetization switched (V50), the results show V50=√ almost independent of intergranular magnetostatic and exchange interactions.

  12. An RTM based Distributed Simulation System for Guide Robot

    Directory of Open Access Journals (Sweden)

    Chen Peihua

    2013-10-01

    Full Text Available In order to enhance the robot system integration and development for guide robot, a distributed simulation system was developed in this study using RTM (Robot Technology Middleware technology, which is an open software platform for robot systems. The RT (robot technology system of an adapter, a controller and the robot, together with other CORBA objects, was developed to connect the graphical programing interface with 3D simulator to set up an RTM based distributed simulation system. Simultaneously, the application of the distributed simulation system also confirms the controlling of the real robot utilizing the RT system. The proposed distributed simulation system based on RTM can obviously accelerate the software component development as well as the system integration for guide robot, which will certainly lower the cost of the development of new robot application systems.

  13. Combining Interactive Thermodynamics Simulations with Screencasts and Conceptests

    Science.gov (United States)

    Falconer, John L.

    2016-01-01

    More than 40 interactive "Mathematica" simulations were prepared for chemical engineering thermodynamics, screencasts were prepared that explain how to use each simulation, and more than 100 ConcepTests were prepared that utilize the simulations. They are located on www.LearnChemE.com. The purposes of these simulations are to clarify…

  14. Simulation study on the impact of air distribution on formaldehyde pollutant distribution in room

    Science.gov (United States)

    Wu, Jingtao; Wang, Jun; Cheng, Zhu

    2017-01-01

    In this paper, physical and mathematical model of a room was established based on the Airpak software. The velocity distribution, air age distribution, formaldehyde concentration distribution and Predicted Mean Vote(PMV), Predicted Percentage Dissatisfied(PPD) distribution in the ward of a hospital were simulated. In addition, the air volume was doubled, the change of indoor pollutant concentration distribution was simulated. And further, the change of air age was simulated. Through the simulation, it can help arrange the position of the air supply port, so it is very necessary to increase the comfort of the staff in the room. Finally, through the simulation of pollutant concentration distribution, it can be seen that when concentration of indoor pollutants was high, the supply air flow rate should be increased appropriately. Indoor pollutant will be discharged as soon as possible, which is very beneficial to human body health.

  15. A Process for Comparing Dynamics of Distributed Space Systems Simulations

    Science.gov (United States)

    Cures, Edwin Z.; Jackson, Albert A.; Morris, Jeffery C.

    2009-01-01

    The paper describes a process that was developed for comparing the primary orbital dynamics behavior between space systems distributed simulations. This process is used to characterize and understand the fundamental fidelities and compatibilities of the modeling of orbital dynamics between spacecraft simulations. This is required for high-latency distributed simulations such as NASA s Integrated Mission Simulation and must be understood when reporting results from simulation executions. This paper presents 10 principal comparison tests along with their rationale and examples of the results. The Integrated Mission Simulation (IMSim) (formerly know as the Distributed Space Exploration Simulation (DSES)) is a NASA research and development project focusing on the technologies and processes that are related to the collaborative simulation of complex space systems involved in the exploration of our solar system. Currently, the NASA centers that are actively participating in the IMSim project are the Ames Research Center, the Jet Propulsion Laboratory (JPL), the Johnson Space Center (JSC), the Kennedy Space Center, the Langley Research Center and the Marshall Space Flight Center. In concept, each center participating in IMSim has its own set of simulation models and environment(s). These simulation tools are used to build the various simulation products that are used for scientific investigation, engineering analysis, system design, training, planning, operations and more. Working individually, these production simulations provide important data to various NASA projects.

  16. Beyond Flory theory: Distribution functions for interacting lattice trees

    Science.gov (United States)

    Rosa, Angelo; Everaers, Ralf

    2017-01-01

    While Flory theories [J. Isaacson and T. C. Lubensky, J. Physique Lett. 41, 469 (1980), 10.1051/jphyslet:019800041019046900; M. Daoud and J. F. Joanny, J. Physique 42, 1359 (1981), 10.1051/jphys:0198100420100135900; A. M. Gutin et al., Macromolecules 26, 1293 (1993), 10.1021/ma00058a016] provide an extremely useful framework for understanding the behavior of interacting, randomly branching polymers, the approach is inherently limited. Here we use a combination of scaling arguments and computer simulations to go beyond a Gaussian description. We analyze distribution functions for a wide variety of quantities characterizing the tree connectivities and conformations for the four different statistical ensembles, which we have studied numerically in [A. Rosa and R. Everaers, J. Phys. A: Math. Theor. 49, 345001 (2016), 10.1088/1751-8113/49/34/345001 and J. Chem. Phys. 145, 164906 (2016), 10.1063/1.4965827]: (a) ideal randomly branching polymers, (b) 2 d and 3 d melts of interacting randomly branching polymers, (c) 3 d self-avoiding trees with annealed connectivity, and (d) 3 d self-avoiding trees with quenched ideal connectivity. In particular, we investigate the distributions (i) pN(n ) of the weight, n , of branches cut from trees of mass N by severing randomly chosen bonds; (ii) pN(l ) of the contour distances, l , between monomers; (iii) pN(r ⃗) of spatial distances, r ⃗, between monomers, and (iv) pN(r ⃗|l ) of the end-to-end distance of paths of length l . Data for different tree sizes superimpose, when expressed as functions of suitably rescaled observables x ⃗=r ⃗/√{ } or x =l / . In particular, we observe a generalized Kramers relation for the branch weight distributions (i) and find that all the other distributions (ii-iv) are of Redner-des Cloizeaux type, q (x ⃗) =C |x| θexp(-(K|x |) t) . We propose a coherent framework, including generalized Fisher-Pincus relations, relating most of the RdC exponents to each other and to the contact and Flory

  17. CAGE IIIA Distributed Simulation Design Methodology

    Science.gov (United States)

    2014-05-01

    Coordination Element AMALO Amphibious Air Liaison Officer AMD Air and Missile Defense AMDWS Air and Missile Defence Work Station AMHS Automated...Object Model (HLA RPR-FOM)8. • Trading off the use of HLA and DIS within clusters of simulations to enable/ disable features required by the larger

  18. Toward Designing a Quantum Key Distribution Network Simulation Model

    Directory of Open Access Journals (Sweden)

    Miralem Mehic

    2016-01-01

    Full Text Available As research in quantum key distribution network technologies grows larger and more complex, the need for highly accurate and scalable simulation technologies becomes important to assess the practical feasibility and foresee difficulties in the practical implementation of theoretical achievements. In this paper, we described the design of simplified simulation environment of the quantum key distribution network with multiple links and nodes. In such simulation environment, we analyzed several routing protocols in terms of the number of sent routing packets, goodput and Packet Delivery Ratio of data traffic flow using NS-3 simulator.

  19. Optimisation of a Crossdocking Distribution Centre Simulation Model

    CERN Document Server

    Adewunmi, Adrian

    2010-01-01

    This paper reports on continuing research into the modelling of an order picking process within a Crossdocking distribution centre using Simulation Optimisation. The aim of this project is to optimise a discrete event simulation model and to understand factors that affect finding its optimal performance. Our initial investigation revealed that the precision of the selected simulation output performance measure and the number of replications required for the evaluation of the optimisation objective function through simulation influences the ability of the optimisation technique. We experimented with Common Random Numbers, in order to improve the precision of our simulation output performance measure, and intended to use the number of replications utilised for this purpose as the initial number of replications for the optimisation of our Crossdocking distribution centre simulation model. Our results demonstrate that we can improve the precision of our selected simulation output performance measure value using C...

  20. An educational tool for interactive parallel and distributed processing

    DEFF Research Database (Denmark)

    Pagliarini, Luigi; Lund, Henrik Hautop

    2012-01-01

    In this article we try to describe how the modular interactive tiles system (MITS) can be a valuable tool for introducing students to interactive parallel and distributed processing programming. This is done by providing a handson educational tool that allows a change in the representation...... of abstract problems related to designing interactive parallel and distributed systems. Indeed, the MITS seems to bring a series of goals into education, such as parallel programming, distributedness, communication protocols, master dependency, software behavioral models, adaptive interactivity, feedback...... interactive parallel and distributed processing with different behavioral software models such as open loop, randomness-based, rule-based, user interaction-based, and AI- and ALife-based software....

  1. Distributed Geant4 simulation in medical and space science applications using DIANE framework and the GRID

    CERN Document Server

    Moscicki, J T; Mantero, A; Pia, M G

    2003-01-01

    Distributed computing is one of the most important trends in IT which has recently gained significance for large-scale scientific applications. Distributed analysis environment (DIANE) is a R&D study, focusing on semiinteractive parallel and remote data analysis and simulation, which has been conducted at CERN. DIANE provides necessary software infrastructure for parallel scientific applications in the master-worker model. Advanced error recovery policies, automatic book-keeping of distributed jobs and on-line monitoring and control tools are provided. DIANE makes a transparent use of a number of different middleware implementations such as load balancing service (LSF, PBS, GRID Resource Broker, Condor) and security service (GSI, Kerberos, openssh). A number of distributed Geant 4 simulations have been deployed and tested, ranging from interactive radiotherapy treatment planning using dedicated clusters in hospitals, to globally-distributed simulations of astrophysics experiments using the European data g...

  2. Spatial distribution sampling and Monte Carlo simulation of radioactive isotopes

    CERN Document Server

    Krainer, Alexander Michael

    2015-01-01

    This work focuses on the implementation of a program for random sampling of uniformly spatially distributed isotopes for Monte Carlo particle simulations and in specific FLUKA. With FLUKA it is possible to calculate the radio nuclide production in high energy fields. The decay of these nuclide, and therefore the resulting radiation field, however can only be simulated in the same geometry. This works gives the tool to simulate the decay of the produced nuclide in other geometries. With that the radiation field from an irradiated object can be simulated in arbitrary environments. The sampling of isotope mixtures was tested by simulating a 50/50 mixture of $Cs^{137}$ and $Co^{60}$. These isotopes are both well known and provide therefore a first reliable benchmark in that respect. The sampling of uniformly distributed coordinates was tested using the histogram test for various spatial distributions. The advantages and disadvantages of the program compared to standard methods are demonstrated in the real life ca...

  3. Micromagnetic evaluation of magnetostatic interactions distribution in structured particulate media

    Energy Technology Data Exchange (ETDEWEB)

    Stancu, Alexandru; Stoleriu, Laurentiu; Cerchez, Mihai

    2001-06-01

    A complex analysis of magnetostatic interactions in particulate media is performed by means of a micromagnetic model. The properties of the interaction field distribution are presented for the case of structured two-dimensional media. The vector properties of the interaction field distribution are also analyzed. The hypothesis concerning interactions in scalar Preisach-type models are validated while the same hypothesis used in vector Preisach models are not entirely in agreement with the physical reality in particulate media. {copyright} 2001 American Institute of Physics.

  4. Design of object-oriented distributed simulation classes

    Science.gov (United States)

    Schoeffler, James D. (Principal Investigator)

    1995-01-01

    Distributed simulation of aircraft engines as part of a computer aided design package is being developed by NASA Lewis Research Center for the aircraft industry. The project is called NPSS, an acronym for 'Numerical Propulsion Simulation System'. NPSS is a flexible object-oriented simulation of aircraft engines requiring high computing speed. It is desirable to run the simulation on a distributed computer system with multiple processors executing portions of the simulation in parallel. The purpose of this research was to investigate object-oriented structures such that individual objects could be distributed. The set of classes used in the simulation must be designed to facilitate parallel computation. Since the portions of the simulation carried out in parallel are not independent of one another, there is the need for communication among the parallel executing processors which in turn implies need for their synchronization. Communication and synchronization can lead to decreased throughput as parallel processors wait for data or synchronization signals from other processors. As a result of this research, the following have been accomplished. The design and implementation of a set of simulation classes which result in a distributed simulation control program have been completed. The design is based upon MIT 'Actor' model of a concurrent object and uses 'connectors' to structure dynamic connections between simulation components. Connectors may be dynamically created according to the distribution of objects among machines at execution time without any programming changes. Measurements of the basic performance have been carried out with the result that communication overhead of the distributed design is swamped by the computation time of modules unless modules have very short execution times per iteration or time step. An analytical performance model based upon queuing network theory has been designed and implemented. Its application to realistic configurations has

  5. Bus.py: A GridLAB-D Communication Interface for Smart Distribution Grid Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Timothy M.; Palmintier, Bryan; Suryanarayanan, Siddharth; Maciejewski, Anthony A.; Siegel, Howard Jay

    2015-07-03

    As more Smart Grid technologies (e.g., distributed photovoltaic, spatially distributed electric vehicle charging) are integrated into distribution grids, static distribution simulations are no longer sufficient for performing modeling and analysis. GridLAB-D is an agent-based distribution system simulation environment that allows fine-grained end-user models, including geospatial and network topology detail. A problem exists in that, without outside intervention, once the GridLAB-D simulation begins execution, it will run to completion without allowing the real-time interaction of Smart Grid controls, such as home energy management systems and aggregator control. We address this lack of runtime interaction by designing a flexible communication interface, Bus.py (pronounced bus-dot-pie), that uses Python to pass messages between one or more GridLAB-D instances and a Smart Grid simulator. This work describes the design and implementation of Bus.py, discusses its usefulness in terms of some Smart Grid scenarios, and provides an example of an aggregator-based residential demand response system interacting with GridLAB-D through Bus.py. The small scale example demonstrates the validity of the interface and shows that an aggregator using said interface is able to control residential loads in GridLAB-D during runtime to cause a reduction in the peak load on the distribution system in (a) peak reduction and (b) time-of-use pricing cases.

  6. Sensitivity of Monte Carlo simulations to input distributions

    Energy Technology Data Exchange (ETDEWEB)

    RamoRao, B. S.; Srikanta Mishra, S.; McNeish, J.; Andrews, R. W.

    2001-07-01

    The sensitivity of the results of a Monte Carlo simulation to the shapes and moments of the probability distributions of the input variables is studied. An economical computational scheme is presented as an alternative to the replicate Monte Carlo simulations and is explained with an illustrative example. (Author) 4 refs.

  7. Validation of Multibody Program to Optimize Simulated Trajectories II Parachute Simulation with Interacting Forces

    Science.gov (United States)

    Raiszadeh, Behzad; Queen, Eric M.; Hotchko, Nathaniel J.

    2009-01-01

    A capability to simulate trajectories of multiple interacting rigid bodies has been developed, tested and validated. This capability uses the Program to Optimize Simulated Trajectories II (POST 2). The standard version of POST 2 allows trajectory simulation of multiple bodies without force interaction. In the current implementation, the force interaction between the parachute and the suspended bodies has been modeled using flexible lines, allowing accurate trajectory simulation of the individual bodies in flight. The POST 2 multibody capability is intended to be general purpose and applicable to any parachute entry trajectory simulation. This research paper explains the motivation for multibody parachute simulation, discusses implementation methods, and presents validation of this capability.

  8. Traffic and Driving Simulator Based on Architecture of Interactive Motion.

    Science.gov (United States)

    Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

    2015-01-01

    This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination.

  9. Traffic and Driving Simulator Based on Architecture of Interactive Motion

    Directory of Open Access Journals (Sweden)

    Alexander Paz

    2015-01-01

    Full Text Available This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i motion-based driving simulation, (ii pedestrian simulation, (iii motorcycling and bicycling simulation, and (iv traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination.

  10. Human Resources Skills: Learning through an Interactive Multimedia Business Simulation.

    Science.gov (United States)

    Klassen, Johanna; Drummond, Damon

    2000-01-01

    Describes and evaluates the design and development of an interactive multimedia simulation package for management education called Business Simulation which combines the concepts of case study methods with business simulation games. It is designed to provide students with skills-based training in human resources management, particularly…

  11. PLEVIS: plant engineering visual and interactive simulator

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Kazuma; Yoshikawa, Eiji; Ohtsuka, Shiroh; Kawakami, Seishiroh (Toshiba Corp., Kawasaki, Kanagawa (Japan))

    1990-07-01

    TOSHIBA has devoted much effort since 1974 to the development of nuclear power plant simulators for operator training, such as replica simulators and compact simulators. These simulators have special purpose consoles or control room equipment for operation training, and run on one or more process computers. Hence they require a large amount of space, e.g. a special room for installation. PLEVIS is a real time plant engineering simulator and operates on a general purpose desk-side engineering workstation (TOSHIBA AS-series) with a high resolution bit-mapped display. The major objectives of PLEVIS are to further improve training performance and efficiency for operators and engineers and to provide a powerful and cost effective plant engineering tool. (author).

  12. Simulated disparity and peripheral blur interact during binocular fusion.

    Science.gov (United States)

    Maiello, Guido; Chessa, Manuela; Solari, Fabio; Bex, Peter J

    2014-07-17

    We have developed a low-cost, practical gaze-contingent display in which natural images are presented to the observer with dioptric blur and stereoscopic disparity that are dependent on the three-dimensional structure of natural scenes. Our system simulates a distribution of retinal blur and depth similar to that experienced in real-world viewing conditions by emmetropic observers. We implemented the system using light-field photographs taken with a plenoptic camera which supports digital refocusing anywhere in the images. We coupled this capability with an eye-tracking system and stereoscopic rendering. With this display, we examine how the time course of binocular fusion depends on depth cues from blur and stereoscopic disparity in naturalistic images. Our results show that disparity and peripheral blur interact to modify eye-movement behavior and facilitate binocular fusion, and the greatest benefit was gained by observers who struggled most to achieve fusion. Even though plenoptic images do not replicate an individual’s aberrations, the results demonstrate that a naturalistic distribution of depth-dependent blur may improve 3-D virtual reality, and that interruptions of this pattern (e.g., with intraocular lenses) which flatten the distribution of retinal blur may adversely affect binocular fusion. © 2014 ARVO.

  13. Simulation of water temperature distribution in Fenhe Reservoir

    Institute of Scientific and Technical Information of China (English)

    Shu-fang FAN; Min-quan FENG; Zhao LIU

    2009-01-01

    In order to evaluate the need of controlling the temperature of water discharged from the Fenhe Reservoir, the reservoir water temperature distribution was examined. A three-dimensional mathematical model was used to simulate the in-plane and vertical distribution of water temperature. The parameters of the model were calibrated with field data of the temperature distribution in the Fenhe Reservoir. The simulated temperature of discharged water is consistent with the measured data. The difference in temperature between the discharged water and the natural river channel is less than 3℃ under the current operating conditions. This will not significantly impact the environment of downstream areas.

  14. Simulation of water temperature distribution in Fenhe Reservoir

    Directory of Open Access Journals (Sweden)

    Shu-fang FAN

    2009-06-01

    Full Text Available Abstract: In order to evaluate the need of controlling the temperature of water discharged from the Fenhe Reservoir, the reservoir water temperature distribution was examined. A three-dimensional mathematical model was used to simulate the in-plane and vertical distribution of water temperature. The parameters of the model were calibrated with field data of the temperature distribution in the Fenhe Reservoir. The simulated temperature of discharged water is consistent with the measured data. The difference in temperature between the discharged water and the natural river channel is less than 3℃ under the current operating conditions. This will not significantly impact the environment of downstream areas.

  15. The distribution of mass components in simulated disc galaxies

    CERN Document Server

    Santos-Santos, Isabel M; Stinson, Greg; Di Cintio, Arianna; Wadsley, James; Domínguez-Tenreiro, Rosa; Gottlöber, Stefan; Yepes, Gustavo

    2015-01-01

    Using 22 hydrodynamical simulated galaxies in a LCDM cosmological context we recover not only the observed baryonic Tully-Fisher relation, but also the observed "mass discrepancy--acceleration" relation, which reflects the distribution of the main components of the galaxies throughout their disks. This implies that the simulations, which span the range 52 < V$_{\\rm flat}$ < 222 km/s where V$_{\\rm flat}$ is the circular velocity at the flat part of the rotation curve, and match galaxy scaling relations, are able to recover the observed relations between the distributions of stars, gas and dark matter over the radial range for which we have observational rotation curve data. Furthermore, we explicitly match the observed baryonic to halo mass relation for the first time with simulated galaxies. We discuss our results in the context of the baryon cycle that is inherent in these simulations, and with regards to the effect of baryonic processes on the distribution of dark matter.

  16. Static load balancing for CFD distributed simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chronopoulos, A T; Grosu, D; Wissink, A; Benche, M

    2001-01-26

    The cost/performance ratio of networks of workstations has been constantly improving. This trend is expected to continue in the near future. The aggregate peak rate of such systems often matches or exceeds the peak rate offered by the fastest parallel computers. This has motivated research towards using a network of computers, interconnected via a fast network (cluster system) or a simple Local Area Network (LAN) (distributed system), for high performance concurrent computations. Some of the important research issues arise such as (1) Optimal problem partitioning and virtual interconnection topology mapping; (2) Optimal execution scheduling and load balancing. CFD codes have been efficiently implemented on homogeneous parallel systems in the past. In particular, the helicopter aerodynamics CFD code TURNS has been implemented with MPI on the IBM SP with parallel relaxation and Krylov iterative methods used in place of more traditional recursive algorithms to enhance performance. In this implementation the space domain is divided into equal subdomain which are mapped to the processors. We consider the implementation of TURNS on a LAN of heterogeneous workstations. In order to deal with the problem of load balancing due to the different processor speeds we propose a suboptimal algorithm of dividing the space domain into unequal subdomains and assign them to the different computers. The algorithm can apply to other CFD applications. We used our algorithm to schedule TURNS on a network of workstations and obtained significantly better results.

  17. Static load balancing for CFD distributed simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chronopoulos, A T; Grosu, D; Wissink, A; Benche, M

    2001-01-26

    The cost/performance ratio of networks of workstations has been constantly improving. This trend is expected to continue in the near future. The aggregate peak rate of such systems often matches or exceeds the peak rate offered by the fastest parallel computers. This has motivated research towards using a network of computers, interconnected via a fast network (cluster system) or a simple Local Area Network (LAN) (distributed system), for high performance concurrent computations. Some of the important research issues arise such as (1) Optimal problem partitioning and virtual interconnection topology mapping; (2) Optimal execution scheduling and load balancing. CFD codes have been efficiently implemented on homogeneous parallel systems in the past. In particular, the helicopter aerodynamics CFD code TURNS has been implemented with MPI on the IBM SP with parallel relaxation and Krylov iterative methods used in place of more traditional recursive algorithms to enhance performance. In this implementation the space domain is divided into equal subdomain which are mapped to the processors. We consider the implementation of TURNS on a LAN of heterogeneous workstations. In order to deal with the problem of load balancing due to the different processor speeds we propose a suboptimal algorithm of dividing the space domain into unequal subdomains and assign them to the different computers. The algorithm can apply to other CFD applications. We used our algorithm to schedule TURNS on a network of workstations and obtained significantly better results.

  18. Comparing models of star formation simulating observed interacting galaxies

    Science.gov (United States)

    Quiroga, L. F.; Muñoz-Cuartas, J. C.; Rodrigues, I.

    2017-07-01

    In this work, we make a comparison between different models of star formation to reproduce observed interacting galaxies. We use observational data to model the evolution of a pair of galaxies undergoing a minor merger. Minor mergers represent situations weakly deviated from the equilibrium configuration but significant changes in star fomation (SF) efficiency can take place, then, minor mergers provide an unique scene to study SF in galaxies in a realistic but yet simple way. Reproducing observed systems also give us the opportunity to compare the results of the simulations with observations, which at the end can be used as probes to characterize the models of SF implemented in the comparison. In this work we compare two different star formation recipes implemented in Gadget3 and GIZMO codes. Both codes share the same numerical background, and differences arise mainly in the star formation recipe they use. We use observations from Pico dos Días and GEMINI telescopes and show how we use observational data of the interacting pair in AM2229-735 to characterize the interacting pair. Later we use this information to simulate the evolution of the system to finally reproduce the observations: Mass distribution, morphology and main features of the merger-induced star formation burst. We show that both methods manage to reproduce roughly the star formation activity. We show, through a careful study, that resolution plays a major role in the reproducibility of the system. In that sense, star formation recipe implemented in GIZMO code has shown a more robust performance. Acknowledgements: This work is supported by Colciencias, Doctorado Nacional - 617 program.

  19. Complex molecular assemblies at hand via interactive simulations.

    Science.gov (United States)

    Delalande, Olivier; Férey, Nicolas; Grasseau, Gilles; Baaden, Marc

    2009-11-30

    Studying complex molecular assemblies interactively is becoming an increasingly appealing approach to molecular modeling. Here we focus on interactive molecular dynamics (IMD) as a textbook example for interactive simulation methods. Such simulations can be useful in exploring and generating hypotheses about the structural and mechanical aspects of biomolecular interactions. For the first time, we carry out low-resolution coarse-grain IMD simulations. Such simplified modeling methods currently appear to be more suitable for interactive experiments and represent a well-balanced compromise between an important gain in computational speed versus a moderate loss in modeling accuracy compared to higher resolution all-atom simulations. This is particularly useful for initial exploration and hypothesis development for rare molecular interaction events. We evaluate which applications are currently feasible using molecular assemblies from 1900 to over 300,000 particles. Three biochemical systems are discussed: the guanylate kinase (GK) enzyme, the outer membrane protease T and the soluble N-ethylmaleimide-sensitive factor attachment protein receptors complex involved in membrane fusion. We induce large conformational changes, carry out interactive docking experiments, probe lipid-protein interactions and are able to sense the mechanical properties of a molecular model. Furthermore, such interactive simulations facilitate exploration of modeling parameters for method improvement. For the purpose of these simulations, we have developed a freely available software library called MDDriver. It uses the IMD protocol from NAMD and facilitates the implementation and application of interactive simulations. With MDDriver it becomes very easy to render any particle-based molecular simulation engine interactive. Here we use its implementation in the Gromacs software as an example.

  20. Interactive Simulated Robot Construction and Controller Evolution

    Science.gov (United States)

    2012-07-09

    evolvability. 2. METHODS The design environment uses the Open Dynamics En- gine (ODE) physics engine with a graphics window and keyboard-driven input to...the allotted time. The simulator captured the time-stamped command keystrokes from each user’s session as well as the simulation environment that...created with an earlier version of the application,which did not include keystroke capture. For this reason, we can- not analyze the user inputs for

  1. Interactive 3D display simulator for autostereoscopic smart pad

    Science.gov (United States)

    Choe, Yeong-Seon; Lee, Ho-Dong; Park, Min-Chul; Son, Jung-Young; Park, Gwi-Tae

    2012-06-01

    There is growing interest of displaying 3D images on a smart pad for entertainments and information services. Designing and realizing various types of 3D displays on the smart pad is not easy for costs and given time. Software simulation can be an alternative method to save and shorten the development. In this paper, we propose a 3D display simulator for autostereoscopic smart pad. It simulates light intensity of each view and crosstalk for smart pad display panels. Designers of 3D display for smart pad can interactively simulate many kinds of autostereoscopic displays interactively by changing parameters required for panel design. Crosstalk to reduce leakage of one eye's image into the image of the other eye, and light intensity for computing visual comfort zone are important factors in designing autostereoscopic display for smart pad. Interaction enables intuitive designs. This paper describes an interactive 3D display simulator for autostereoscopic smart pad.

  2. XNsim: Internet-Enabled Collaborative Distributed Simulation via an Extensible Network

    Science.gov (United States)

    Novotny, John; Karpov, Igor; Zhang, Chendi; Bedrossian, Nazareth S.

    2007-01-01

    In this paper, the XNsim approach to achieve Internet-enabled, dynamically scalable collaborative distributed simulation capabilities is presented. With this approach, a complete simulation can be assembled from shared component subsystems written in different formats, that run on different computing platforms, with different sampling rates, in different geographic locations, and over singlelmultiple networks. The subsystems interact securely with each other via the Internet. Furthermore, the simulation topology can be dynamically modified. The distributed simulation uses a combination of hub-and-spoke and peer-topeer network topology. A proof-of-concept demonstrator is also presented. The XNsim demonstrator can be accessed at http://www.jsc.draver.corn/xn that hosts various examples of Internet enabled simulations.

  3. A Distributed Simulation Software System for Multi-Spacecraft Missions

    Science.gov (United States)

    Burns, Richard; Davis, George; Cary, Everett

    2003-01-01

    The paper will provide an overview of the web-based distributed simulation software system developed for end-to-end, multi-spacecraft mission design, analysis, and test at the NASA Goddard Space Flight Center (GSFC). This software system was developed for an internal research and development (IR&D) activity at GSFC called the Distributed Space Systems (DSS) Distributed Synthesis Environment (DSE). The long-term goal of the DSS-DSE is to integrate existing GSFC stand-alone test beds, models, and simulation systems to create a "hands on", end-to-end simulation environment for mission design, trade studies and simulations. The short-term goal of the DSE was therefore to develop the system architecture, and then to prototype the core software simulation capability based on a distributed computing approach, with demonstrations of some key capabilities by the end of Fiscal Year 2002 (FY02). To achieve the DSS-DSE IR&D objective, the team adopted a reference model and mission upon which FY02 capabilities were developed. The software was prototyped according to the reference model, and demonstrations were conducted for the reference mission to validate interfaces, concepts, etc. The reference model, illustrated in Fig. 1, included both space and ground elements, with functional capabilities such as spacecraft dynamics and control, science data collection, space-to-space and space-to-ground communications, mission operations, science operations, and data processing, archival and distribution addressed.

  4. Remarks on long range interactions in simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pollock, E L

    1999-08-11

    Long range interactions in periodic systems should be treated using the Ewald potential. For systems larger than a few hundred particles this is best calculated using the particle-particle, particle-mesh (P3M) method.

  5. Remarks on long range interactions in simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pollock, E L

    1999-08-11

    Long range interactions in periodic systems should be treated using the Ewald potential. For systems larger than a few hundred particles this is best calculated using the particle-particle, particle-mesh (P3M) method.

  6. A Framework for the Interactive Handling of High-Dimensional Simulation Data in Complex Geometries

    KAUST Repository

    Benzina, Amal

    2013-01-01

    Flow simulations around building infrastructure models involve large scale complex geometries, which when discretized in adequate detail entail high computational cost. Moreover, tasks such as simulation insight by steering or optimization require many such costly simulations. In this paper, we illustrate the whole pipeline of an integrated solution for interactive computational steering, developed for complex flow simulation scenarios that depend on a moderate number of both geometric and physical parameters. A mesh generator takes building information model input data and outputs a valid cartesian discretization. A sparse-grids-based surrogate model—a less costly substitute for the parameterized simulation—uses precomputed data to deliver approximated simulation results at interactive rates. Furthermore, a distributed multi-display visualization environment shows building infrastructure together with flow data. The focus is set on scalability and intuitive user interaction.

  7. Particles inside electrolytes with ion-specific interactions, their effective charge distributions, and effective interactions

    Science.gov (United States)

    Ding, Mingnan; Liang, Yihao; Xing, Xiangjun

    2016-10-01

    In this work, we explore the statistical physics of colloidal particles that interact with electrolytes via ion-specific interactions. Firstly we study particles interacting weakly with electrolyte using linear response theory. We find that the mean potential around a particle is linearly determined by the effective charge distribution of the particle, which depends both on the bare charge distribution and on ion-specific interactions. We also discuss the effective interaction between two such particles and show that, in the far field regime, it is bilinear in the effective charge distributions of two particles. We subsequently generalize the above results to the more complicated case where particles interact strongly with the electrolyte. Our results indicate that in order to understand the statistical physics of non-dilute electrolytes, both ion-specific interactions and ionic correlations have to be addressed in a single unified and consistent framework. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174196 and 91130012).

  8. Simulation of energy barrier distributions using real particle parameters and comparison with experimental obtained results

    Energy Technology Data Exchange (ETDEWEB)

    Büttner, M., E-mail: Markus.Buettner@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena (Germany); Schiffler, M. [Institut für Geowissenschaften, Friedrich-Schiller-Universität Jena, Burgweg 11, 07749 Jena (Germany); Weber, P.; Seidel, P. [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena (Germany)

    2013-11-15

    Distributions of energy barriers in systems of magnetic nanoparticles have been calculated by means of the path integral method and the results have been compared with distributions previously obtained in our experiments by means of the temperature dependent magnetorelaxation method. The path integral method allowed to obtain energies of the interactions of magnetic moments of nanoparticles with axes of their easy magnetisation as well as energies of mutual interactions of magnetic moments. Calculated distributions of energy barriers have been described satisfactorily by curves of the lognormal distribution. We found an agreement between the theory and the experiment at temperatures above approximately 100 K. The influence of the volume concentration of nanoparticles and agglomeration on the energy barrier distribution has been investigated. - Highlights: • The path integral method of calculation allows to satisfactorily reproduce the quantitative experimental results. • The simulations of the energy barrier distributions reflect the lognormal distribution of the MNP found in real experiments. • Higher particle volume concentration leads to a broadening of the simulated energy barrier distribution. • At low particle concentration there is only anisotropy energy. • In case of agglomeration the energy barrier distribution broadens.

  9. Shock Particle Interaction - Fully Resolved Simulations and Modeling

    Science.gov (United States)

    Mehta, Yash; Neal, Chris; Jackson, Thomas L.; Balachandar, S. "Bala"; Thakur, Siddharth

    2016-11-01

    Currently there is a substantial lack of fully resolved data for shock interacting with multiple particles. In this talk we will fill this gap by presenting results of shock interaction with 1-D array and 3-D structured arrays of particles. Objectives of performing fully resolved simulations of shock propagation through packs of multiple particles are twofold, 1) To understand the complicated physical phenomena occurring during shock particle interaction, and 2) To translate the knowledge from microscale simulations in building next generation point-particle models for macroscale simulations that can better predict the motion (forces) and heat transfer for particles. We compare results from multiple particle simulations against the single particle simulations and make relevant observations. The drag history and flow field for multiple particle simulations are markedly different from those of single particle simluations, highlighting the effect of neighboring particles. We propose new models which capture this effect of neighboring particles. These models are called Pair-wise Interaction Extended Point Particle models (PIEP). Effect of multiple neighboring particles is broken down into pair-wise interactions, and these pair-wise interactions are superimposed to get the final model U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

  10. Simulating Heinrich event 1 with interactive icebergs

    NARCIS (Netherlands)

    Jongma, J.I.; Renssen, H.; Roche, D.M.V.A.P.

    2012-01-01

    During the last glacial, major abrupt climate events known as Heinrich events left distinct fingerprints of ice rafted detritus, and are thus associated with iceberg armadas; the release of many icebergs into the North Atlantic Ocean. We simulated the impact of a large armada of icebergs on glacial

  11. Simulation of Tasks Distribution in Horizontally Scalable Management System

    Science.gov (United States)

    Kustov, D.; Sherstneva, A.; Botygin, I.

    2016-08-01

    This paper presents an imitational model of the task distribution system for the components of territorially-distributed automated management system with a dynamically changing topology. Each resource of the distributed automated management system is represented with an agent, which allows to set behavior of every resource in the best possible way and ensure their interaction. The agent work load imitation was done via service query imitation formed in a system dynamics style using a stream diagram. The query generation took place in the abstract-represented center - afterwards, they were sent to the drive to be distributed to management system resources according to a ranking table.

  12. Challenges in reducing the computational time of QSTS simulations for distribution system analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Deboever, Jeremiah [Georgia Inst. of Technology, Atlanta, GA (United States); Zhang, Xiaochen [Georgia Inst. of Technology, Atlanta, GA (United States); Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States); Therrien, Francis [CME International T& D, St. Bruno, QC (Canada)

    2017-06-01

    The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modelling and impact analysis. Unlike conventional scenario - based studies , quasi - static time - series (QSTS) simulation s can realistically model time - dependent voltage controllers and the diversity of potential impacts that can occur at different times of year . However, to accurately model a distribution system with all its controllable devices, a yearlong simulation at 1 - second resolution is often required , which could take conventional computers a computational time of 10 to 120 hours when an actual unbalanced distribution feeder is modeled . This computational burden is a clear l imitation to the adoption of QSTS simulation s in interconnection studies and for determining optimal control solutions for utility operations . Our ongoing research to improve the speed of QSTS simulation has revealed many unique aspects of distribution system modelling and sequential power flow analysis that make fast QSTS a very difficult problem to solve. In this report , the most relevant challenges in reducing the computational time of QSTS simulations are presented: number of power flows to solve, circuit complexity, time dependence between time steps, multiple valid power flow solutions, controllable element interactions, and extensive accurate simulation analysis.

  13. Timing interactions in social simulations: The voter model

    CERN Document Server

    Fernández-Gracia, Juan; Miguel, Maxi San

    2013-01-01

    The recent availability of huge high resolution datasets on human activities has revealed the heavy-tailed nature of the interevent time distributions. In social simulations of interacting agents the standard approach has been to use Poisson processes to update the state of the agents, which gives rise to very homogeneous activity patterns with a well defined characteristic interevent time. As a paradigmatic opinion model we investigate the voter model and review the standard update rules and propose two new update rules which are able to account for heterogeneous activity patterns. For the new update rules each node gets updated with a probability that depends on the time since the last event of the node, where an event can be an update attempt (exogenous update) or a change of state (endogenous update). We find that both update rules can give rise to power law interevent time distributions, although the endogenous one more robustly. Apart from that for the exogenous update rule and the standard update rules...

  14. Timing Interactions in Social Simulations: The Voter Model

    Science.gov (United States)

    Fernández-Gracia, Juan; Eguíluz, Víctor M.; Miguel, Maxi San

    The recent availability of huge high resolution datasets on human activities has revealed the heavy-tailed nature of the interevent time distributions. In social simulations of interacting agents the standard approach has been to use Poisson processes to update the state of the agents, which gives rise to very homogeneous activity patterns with a well defined characteristic interevent time. As a paradigmatic opinion model we investigate the voter model and review the standard update rules and propose two new update rules which are able to account for heterogeneous activity patterns. For the new update rules each node gets updated with a probability that depends on the time since the last event of the node, where an event can be an update attempt (exogenous update) or a change of state (endogenous update). We find that both update rules can give rise to power law interevent time distributions, although the endogenous one more robustly. Apart from that for the exogenous update rule and the standard update rules the voter model does not reach consensus in the infinite size limit, while for the endogenous update there exist a coarsening process that drives the system toward consensus configurations.

  15. Simulating market dynamics: interactions between consumer psychology and social networks.

    Science.gov (United States)

    Janssen, Marco A; Jager, Wander

    2003-01-01

    Markets can show different types of dynamics, from quiet markets dominated by one or a few products, to markets with continual penetration of new and reintroduced products. In a previous article we explored the dynamics of markets from a psychological perspective using a multi-agent simulation model. The main results indicated that the behavioral rules dominating the artificial consumer's decision making determine the resulting market dynamics, such as fashions, lock-in, and unstable renewal. Results also show the importance of psychological variables like social networks, preferences, and the need for identity to explain the dynamics of markets. In this article we extend this work in two directions. First, we will focus on a more systematic investigation of the effects of different network structures. The previous article was based on Watts and Strogatz's approach, which describes the small-world and clustering characteristics in networks. More recent research demonstrated that many large networks display a scale-free power-law distribution for node connectivity. In terms of market dynamics this may imply that a small proportion of consumers may have an exceptional influence on the consumptive behavior of others (hubs, or early adapters). We show that market dynamics is a self-organized property depending on the interaction between the agents' decision-making process (heuristics), the product characteristics (degree of satisfaction of unit of consumption, visibility), and the structure of interactions between agents (size of network and hubs in a social network).

  16. Numerical Simulation of Wind Turbine Blade-Tower Interaction

    Institute of Scientific and Technical Information of China (English)

    Qiang Wang; Hu Zhou; Decheng Wan

    2012-01-01

    Numerical simulations of wind turbine blade-tower interaction by using the open source OpenFOAM tools coupled with arbitrary mesh interface (AMI) method were presented.The governing equations were the unsteady Reynolds-averaged Navier-Stokes (PANS) which were solved by the pimpleDyMFoam solver,and the AMI method was employed to handle mesh movements.The National Renewable Energy Laboratory (NREL) phase Ⅵ wind turbine in upwind configuration was selected for numerical tests with different incoming wind speeds (5,10,15,and 25 m/s) at a fixed blade pitch and constant rotational speed.Detailed numerical results of vortex structure,time histories of thrust,and pressure distribution on the blade and tower were presented.The findings show that the wind turbine tower has little effect on the whole aerodynamic performance of an upwind wind turbine,while the rotating rotor will induce an obvious cyclic drop in the front pressure of the tower.Also,strong interaction of blade tip vortices with separation from the tower was observed.

  17. The Electron Transport Chain: An Interactive Simulation

    Science.gov (United States)

    Romero, Chris; Choun, James

    2014-01-01

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

  18. The Electron Transport Chain: An Interactive Simulation

    Science.gov (United States)

    Romero, Chris; Choun, James

    2014-01-01

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

  19. Interactive Classroom Graphics--Simulating Non-Linear Arrhenius Plots.

    Science.gov (United States)

    Ben-Zion, M.; Hoz, S.

    1980-01-01

    Describes two simulation programs using an interactive graphic display terminal that were developed for a course in physical organic chemistry. Demonstrates the energetic conditions that give rise to deviations from linearity in the Arrhenius equation. (CS)

  20. Simulation of distribution of radiation energy density in water balls

    Institute of Scientific and Technical Information of China (English)

    TANG Shi-Biao; MA Qing-Li; YIN Ze-Jie; TANG Yu; HUANG Huan; RAO Nan-Xia; ZHU Da-Ming

    2005-01-01

    The distribution of energy deposition density in radiate region and its surrounding areas from γ-rays was simulated and analyzed for a water-ball model with Geant4 package ( Geant4.7.0,2005 ) developed by CERN (the Center of European Research of Nucleus). The results show that the distribution depends strongly on the collimating condition of radiation beam. A well-collimated beam would reduce radiation effects on surrounding areas.

  1. Interactive Modelling and Simulation of Human Motion

    DEFF Research Database (Denmark)

    Engell-Nørregård, Morten Pol

    Dansk resumé Denne ph.d.-afhandling beskæftiger sig med modellering og simulation af menneskelig bevægelse. Emnerne i denne afhandling har mindst to ting til fælles. For det første beskæftiger de sig med menneskelig bevægelse. Selv om de udviklede modeller også kan benyttes til andre ting,er det ....... Endvidere kan den anvendes med enhver softbody simuleringsmodel som finite elements eller mass spring systemer. • En kontrol metode til deformerbare legemer baseret på rum tids opti- mering. fremgangsmåden kan anvendes til at styre sammentrækning af muskler i en muskel simulering....

  2. Simulation of Gas-Surface Dynamical Interactions

    Science.gov (United States)

    2007-07-01

    Brenig, Z. Phys. B 36, 81 (1979). [39] J. Böheim and W. Brenig, Z. Phys. B 41, 243 (1981). [40] G. B. Arfken and H. J. Weber, Mathematical Methods for...excitation of the substrate have to be taken into account. In this lecture, the quantum and classical methods required for the simulation of gas-surface...well-defined conditions [2]. In this chapter, I will briefly review the theoretical methods necessary to determine the dynamics of processes at surfaces

  3. Simulation of interactions at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Duckeck, Guenter [Munich Univ. (Germany). Physics Faculty

    2016-11-01

    The LHC Run-2 is planned to continue until end of 2018 and should increase the data volume by at least a factor 5 compared to Run-1. A corresponding increase of the simulated data volume is required in order to analyze and interpret the recorded data. This will allow us to determine with much better precision the properties of the Higgs Boson and either find new particles as predicted by 'New Physics' theories or further increase the constraints on these models. Using SuperMUC to simulate events will be a crucial component to reach these goals. Active development of the simulation software is ongoing in order to make the workflow more flexible and better parallelizable for smaller work-units. Adapting the software for Intel/Mic architectures is an important goal, though presumably more in the long-term after LHC Run-2 (Run-3 is planned to start in 2021). We would hope that ''SuperMUC Next Generation'' provides Intel/Mic architecture extensions.

  4. Interactive Modelling and Simulation of Human Motion

    DEFF Research Database (Denmark)

    Engell-Nørregård, Morten Pol

    Dansk resumé Denne ph.d.-afhandling beskæftiger sig med modellering og simulation af menneskelig bevægelse. Emnerne i denne afhandling har mindst to ting til fælles. For det første beskæftiger de sig med menneskelig bevægelse. Selv om de udviklede modeller også kan benyttes til andre ting,er det...... menneskers led, der udviser både ikke-konveksitet og flere frihedsgrader • En generel og alsidig model for aktivering af bløde legemer. Modellen kan anvendes som et animations værktøj, men er lige så velegnet til simulering af menneskelige muskler, da den opfylder de grundlæggende fysiske principper...... primære fokus på at modellere den menneskelige krop. For det andet, beskæftiger de sig alle med simulering som et redskab til at syntetisere bevægelse og dermed skabe animationer. Dette er en vigtigt pointe, da det betyder, at vi ikke kun skaber værktøjer til animatorer, som de kan bruge til at lave sjove...

  5. An open source platform for multi-scale spatially distributed simulations of microbial ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Segre, Daniel [Boston Univ., MA (United States)

    2014-08-14

    The goal of this project was to develop a tool for facilitating simulation, validation and discovery of multiscale dynamical processes in microbial ecosystems. This led to the development of an open-source software platform for Computation Of Microbial Ecosystems in Time and Space (COMETS). COMETS performs spatially distributed time-dependent flux balance based simulations of microbial metabolism. Our plan involved building the software platform itself, calibrating and testing it through comparison with experimental data, and integrating simulations and experiments to address important open questions on the evolution and dynamics of cross-feeding interactions between microbial species.

  6. An Interactive Simulation Tool for Production Planning in Bacon Factories

    DEFF Research Database (Denmark)

    Nielsen, Jens Frederik Dalsgaard; Nielsen, Kirsten Mølgaard

    1994-01-01

    The paper describes an interactive simulation tool for production planning in bacon factories. The main aim of the tool is to make it possible to combine the production plans of all parts of the factory......The paper describes an interactive simulation tool for production planning in bacon factories. The main aim of the tool is to make it possible to combine the production plans of all parts of the factory...

  7. Impact of interactive vegetation phenology on the simulated pan-Arctic land surface state

    Science.gov (United States)

    Teufel, Bernardo; Sushama, Laxmi

    2016-04-01

    The pan-Arctic land surface is undergoing rapid changes in a warming climate, with near-surface permafrost projected to degrade significantly during the 21st century. This can have important impacts on the regional climate and hydrology through various feedbacks, including vegetation-related feedbacks. In this study, the impact of interactive phenology on the land surface state, including near-surface permafrost, is assessed by comparing two simulations of the Canadian Land Surface Scheme (CLASS) - one with interactive phenology, modelled using the Canadian Terrestrial Ecosystem Model (CTEM), and the other with prescribed phenology. These simulations are performed for the 1979-2012 period, using atmospheric forcing from ECMWF's ERA-Interim reanalysis. The impact of interactive phenology on projected changes to the land surface state are also assessed by comparing two simulations of CLASS (with and without interactive phenology), spanning the 1961-2100 period, driven by atmospheric forcing from a transient climate change simulation of the 5th generation Canadian Regional Climate Model (CRCM5) for the Representative Concentration Pathway 8.5 (RCP8.5). Comparison of the CLASS coupled to CTEM simulation with available observational estimates of plant area index, primary productivity, spatial distribution of permafrost and active layer thickness suggests that the model captures reasonably well the general distribution of vegetation and permafrost. Significant differences in evapotranspiration, leading to differences in runoff, soil temperature and active layer thickness are noted when comparing CLASS simulations with and without interactive phenology. Furthermore, the CLASS simulations with and without interactive phenology for RCP8.5 show extensive near-surface permafrost degradation by the end of the 21st century, with slightly accelerated degradation of permafrost in the simulation with interactive phenology, pointing towards a positive feedback of changes in

  8. Web-Based Distributed Simulation of Aeronautical Propulsion System

    Science.gov (United States)

    Zheng, Desheng; Follen, Gregory J.; Pavlik, William R.; Kim, Chan M.; Liu, Xianyou; Blaser, Tammy M.; Lopez, Isaac

    2001-01-01

    An application was developed to allow users to run and view the Numerical Propulsion System Simulation (NPSS) engine simulations from web browsers. Simulations were performed on multiple INFORMATION POWER GRID (IPG) test beds. The Common Object Request Broker Architecture (CORBA) was used for brokering data exchange among machines and IPG/Globus for job scheduling and remote process invocation. Web server scripting was performed by JavaServer Pages (JSP). This application has proven to be an effective and efficient way to couple heterogeneous distributed components.

  9. Global simulation of interactions between groundwater and terrestrial ecosystems

    Science.gov (United States)

    Braakhekke, M. C.; Rebel, K.; Dekker, S. C.; Smith, B.; Van Beek, L. P.; Sutanudjaja, E.; van Kampenhout, L.; Wassen, M. J.

    2016-12-01

    In many places in the world ecosystems are influenced by the presence of a shallow groundwater table. In these regions upward water flux due to capillary rise increases soil moisture availability in the root zone, which has strong positive effect on evapotranspiration. Additionally it has important consequences for vegetation dynamics and fluxes of carbon and nitrogen. Under water limited conditions shallow groundwater stimulates vegetation productivity, and soil organic matter decomposition while under saturated conditions groundwater may have a negative effect on these processes due to lack of oxygen. Furthermore, since plant species differ with respect to their root distribution, preference for moisture conditions, and resistance to oxygen stress, shallow groundwater also influences vegetation type. Finally, processes such as denitrification and methane production occur under strictly anaerobic conditions and are thus strongly influenced by moisture availability. Most global hydrological models and several land surface models simulate groundwater table dynamics and their effects on land surface processes. However, these models typically have relatively simplistic representation of vegetation and do not consider changes in vegetation type and structure and are therefore less suitable to represent effects of groundwater on biogeochemical fluxes. Dynamic global vegetation models (DGVMs), describe land surface from an ecological perspective, combining detailed description of vegetation dynamics and structure and biogeochemical processes. These models are thus more appropriate to simulate the ecological and biogeochemical effects of groundwater interactions. However, currently virtually all DGVMs ignore these effects, assuming that water tables are too deep to affect soil moisture in the root zone. We have implemented a tight coupling between the dynamic global ecosystem model LPJ-GUESS and the global hydrological model PCR-GLOBWB. Using this coupled model we aim to

  10. Gyrokinetic simulations with a general equilibrium distribution function

    Science.gov (United States)

    Wilkie, George; Highcock, Edmund; Abel, Ian; Dorland, William

    2013-10-01

    Applying the gyrokinetic framework to study the dynamics of fast particles requires a transport-scale equilibrium distribution that is not Maxwellian, and whose functional form may not be known a priori. The GS2 gyrokinetics code has been modified to accommodate an arbitrary equilibrium distribution and this capability has been validated. The need to resolve the tail of the distribution for fast particles introduces numerical challenges that are resolved by implementing a generalized quadrature scheme that retains spectral accuracy of velocity-space integrals. Preliminary simulation results are presented.

  11. New electron multiple scattering distributions for Monte Carlo transport simulation

    Energy Technology Data Exchange (ETDEWEB)

    Chibani, Omar (Haut Commissariat a la Recherche (C.R.S.), 2 Boulevard Franz Fanon, Alger B.P. 1017, Alger-Gare (Algeria)); Patau, Jean Paul (Laboratoire de Biophysique et Biomathematiques, Faculte des Sciences Pharmaceutiques, Universite Paul Sabatier, 35 Chemin des Maraichers, 31062 Toulouse cedex (France))

    1994-10-01

    New forms of electron (positron) multiple scattering distributions are proposed. The first is intended for use in the conditions of validity of the Moliere theory. The second distribution takes place when the electron path is so short that only few elastic collisions occur. These distributions are adjustable formulas. The introduction of some parameters allows impositions of the correct value of the first moment. Only positive and analytic functions were used in constructing the present expressions. This makes sampling procedures easier. Systematic tests are presented and some Monte Carlo simulations, as benchmarks, are carried out. ((orig.))

  12. {sup 19}F MRI oximetry: simulation of perfluorocarbon distribution impact

    Energy Technology Data Exchange (ETDEWEB)

    Baete, S H; Vandecasteele, J; De Deene, Y, E-mail: steven.baete@ugent.be [Department of Radiation Oncology and Experimental Cancer Research, Ghent University, De Pintelaan 185, 9000 Gent (Belgium)

    2011-04-21

    In {sup 19}F MRI oximetry, a method used to image tumour hypoxia, perfluorocarbons serve as oxygenation markers. The goal of this study is to evaluate the impact of perfluorocarbon distribution and concentration in {sup 19}F MRI oximetry through a computer simulation. The simulation studies the correspondence between {sup 19}F measured (pO{sup FNMR}{sub 2}) and actual tissue oxygen tension (pO{sub 2}) for several tissue perfluorocarbon distributions. For this, a Krogh tissue model is implemented which incorporates the presence of perfluorocarbons in blood and tissue. That is, in tissue the perfluorocarbons are distributed homogeneously according to Gaussian diffusion profiles, or the perfluorocarbons are concentrated in the capillary wall. Using these distributions, the oxygen tension in the simulation volume is calculated. The simulated mean oxygen tension is then compared with pO{sup FNMR}{sub 2}, the {sup 19}F MRI-based measure of pO{sub 2} and with pO{sup 0}{sub 2}, pO{sub 2} in the absence of perfluorocarbons. The agreement between pO{sup FNMR}{sub 2} and actual pO{sub 2} is influenced by vascular density and perfluorocarbon distribution. The presence of perfluorocarbons generally gives rise to a pO{sub 2} increase in tissue. This effect is enhanced when perfluorocarbons are also present in blood. Only the homogeneous perfluorocarbon distribution in tissue with no perfluorocarbons in blood guarantees small deviations of pO{sup FNMR}{sub 2} from pO{sub 2}. Hence, perfluorocarbon distribution in tissue and blood has a serious impact on the reliability of {sup 19}F MRI-based measures of oxygen tension. In addition, the presence of perfluorocarbons influences the actual oxygen tension. This finding may be of great importance for further development of {sup 19}F MRI oximetry.

  13. 19F MRI oximetry: simulation of perfluorocarbon distribution impact

    Science.gov (United States)

    Baete, S. H.; Vandecasteele, J.; De Deene, Y.

    2011-04-01

    In 19F MRI oximetry, a method used to image tumour hypoxia, perfluorocarbons serve as oxygenation markers. The goal of this study is to evaluate the impact of perfluorocarbon distribution and concentration in 19F MRI oximetry through a computer simulation. The simulation studies the correspondence between 19F measured (pOFNMR2) and actual tissue oxygen tension (pO2) for several tissue perfluorocarbon distributions. For this, a Krogh tissue model is implemented which incorporates the presence of perfluorocarbons in blood and tissue. That is, in tissue the perfluorocarbons are distributed homogeneously according to Gaussian diffusion profiles, or the perfluorocarbons are concentrated in the capillary wall. Using these distributions, the oxygen tension in the simulation volume is calculated. The simulated mean oxygen tension is then compared with pOFNMR2, the 19F MRI-based measure of pO2 and with pO02, pO2 in the absence of perfluorocarbons. The agreement between pOFNMR2 and actual pO2 is influenced by vascular density and perfluorocarbon distribution. The presence of perfluorocarbons generally gives rise to a pO2 increase in tissue. This effect is enhanced when perfluorocarbons are also present in blood. Only the homogeneous perfluorocarbon distribution in tissue with no perfluorocarbons in blood guarantees small deviations of pOFNMR2 from pO2. Hence, perfluorocarbon distribution in tissue and blood has a serious impact on the reliability of 19F MRI-based measures of oxygen tension. In addition, the presence of perfluorocarbons influences the actual oxygen tension. This finding may be of great importance for further development of 19F MRI oximetry.

  14. An agent-based interaction model for Chinese personal income distribution

    Science.gov (United States)

    Zou, Yijiang; Deng, Weibing; Li, Wei; Cai, Xu

    2015-10-01

    The personal income distribution in China was studied by employing the data from China Household Income Projects (CHIP) between 1990 and 2002. It was observed that the low and middle income regions could be described by the log-normal law, while the large income region could be well fitted by the power law. To characterize these empirical findings, a stochastic interactive model with mean-field approach was discussed, and the analytic result shows that the wealth distribution is of the Pareto type. Then we explored the agent-based model on networks, in which the exchange of wealth among agents depends on their connectivity. Numerical results suggest that the wealth of agents would largely rely on their connectivity, and the Pareto index of the simulated wealth distributions is comparable to those of the empirical data. The Pareto behavior of the tails of the empirical wealth distributions is consistent with that of the 'mean-field' model, as well as numerical simulations.

  15. Schemes of Repeater Optimizing Distribution based on the MLC Application and CBLRD Simulation

    Directory of Open Access Journals (Sweden)

    Qian Qiuye

    2013-07-01

    Full Text Available The widely use of repeaters raises concern about their coordination among the public. Since repeaters may suffer interaction and limitation bearing capacity, designing a reasonable repeaters coordination method is of great significance. This study address the problem if repeater coordination in a circular flat area with minimal number of repeaters with seamless coverage theory, system simulation method. With 1,000 users, this study model the coverage, getting the minimal number of repeaters of different coverage radius based on extensive used regular hexagon coverage theory. A numerical example was given in this case. When the number of users increases to 10,000, this study simulate to get the signal density across the area according to the consideration of repeaters and the different distribution of users, which are divided into uniform distribution, linear distribution, normal distribution and lognormal distribution. Then, Multi-Layer Coverage (MLC and Coverage by Link Rate Density (CBLRD are created as the distribution scheme on the area where repeat service demand is large. Moreover, for solution on the distribution of the repeaters with barriers, distribution schemes are given considering the transmission of VHF spectrums and the distribution of users around the barrier. Additionally, Spring Comfortable Degree (SCD is used for evaluation of the results and the developing tends are given to improve the model. Due to the reasonable assumption, the solution of repeater distribution is of pivotal reference value based on the reasonable results.

  16. Agent based models for wealth distribution with preference in interaction

    CERN Document Server

    Goswami, Sanchari

    2014-01-01

    We propose a set of conservative models in which agents exchange wealth with a preference in the choice of interacting agents in different ways. The common feature in all the models is that the temporary values of financial status of agents is a deciding factor for interaction. Other factors which may play important role are past interactions and wealth possessed by individuals. Wealth distribution, network properties and activity are the main quantities which have been studied. Evidence of phase transitions and other interesting features are presented. The results show that certain observations of real economic system can be reproduced by the models.

  17. Interfacial interaction between polypropylene and nanotube: A molecular dynamics simulation

    Science.gov (United States)

    Zhang, Danhui; Yang, Houbo; Liu, Zhongkui; Liu, Anmin; Li, Yunfang

    2017-09-01

    The interfacial interaction between polypropylene (PE) and single walled carbon nanotube (SWCNT) was studied using molecular dynamics (MD) simulations. The result showed that the PE chain could stabilize the SWCNT and then extended along the direction of SWCNT. The mechanism of interfacial interaction between PE and SWCNT was also discussed. Furthermore, the interfacial interaction between more PE and SWCNT was also investigated and the position also deeply influenced the interaction. This will be beneficial to understanding the interfacial interaction between polymer and CNT in solution, and also guiding the fabrication of high performance polymer/CNT nanocomposites.

  18. Interactive simulation of technology management foresight

    DEFF Research Database (Denmark)

    Hansen, Mette Sanne; Rasmussen, Lauge Baungaard; Jacobsen, Peter

    2013-01-01

    Two of the main foresight challenges are how to handle complexity and uncertainty of evolving technology tracks, which may merge and create new challenges for the management of a company in order to avoid sub- optimization. Complexity refers to the difficulty of identifying and quantifying causal...... as a number of intervening stakeholders at different levels of technology management in an organization. Uncertainty comprises lack of knowledge in addition to variable responses of management to identical technological tracks. The purpose of this paper is to identify and reflect on the obstacles...... and possibilities of using the combination of narrative and numerical simulation to explore uncertainties and complexities of technology development and implementation in companies. Foresight as a method to develop technology management strategies can hardly be organized as a separated step by step procedure...

  19. Interactive Room Support for Complex and Distributed Design Projects

    DEFF Research Database (Denmark)

    Grønbæk, Kaj; Gundersen, Kristian Kroyer; Mogensen, Preben Holst

    2001-01-01

    notion of interactive room technology supporting industrial design and describes two examples of this technology: the Designers' Workbench and the 3D Whiteboard, both integrated in a common distributed and collaborative infrastructure. The paper also describes a number of new easy-to-grab and lightweight...

  20. Simulating heterogeneous user behaviors to interact with conversational interfaces

    Directory of Open Access Journals (Sweden)

    David GRIOL

    2016-12-01

    Full Text Available Research in techniques to simulate users has a long history within the fields of language processing, speech technologies and conversational interfaces. In this paper, we describe a technique to develop heterogeneous user models that are able to interact with this kind of interfaces. By means of simulated users, it is possible not only to automatically evaluate the overall operation of a conversational interface, but also to assess the impact of the user responses on the decisions that are selected by the system. The selection of the user responses by the simulated user are based on a statistical model that considers the complete history of the interaction to carry out this selection. We describe this technique and its practical application to measure the influence of the most important user's features characteristics that affect the interaction of the simulated user with the a conversational interface.

  1. Simulating human behavior for national security human interactions.

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, Michael Lewis; Hart, Dereck H.; Verzi, Stephen J.; Glickman, Matthew R.; Wolfenbarger, Paul R.; Xavier, Patrick Gordon

    2007-01-01

    This 3-year research and development effort focused on what we believe is a significant technical gap in existing modeling and simulation capabilities: the representation of plausible human cognition and behaviors within a dynamic, simulated environment. Specifically, the intent of the ''Simulating Human Behavior for National Security Human Interactions'' project was to demonstrate initial simulated human modeling capability that realistically represents intra- and inter-group interaction behaviors between simulated humans and human-controlled avatars as they respond to their environment. Significant process was made towards simulating human behaviors through the development of a framework that produces realistic characteristics and movement. The simulated humans were created from models designed to be psychologically plausible by being based on robust psychological research and theory. Progress was also made towards enhancing Sandia National Laboratories existing cognitive models to support culturally plausible behaviors that are important in representing group interactions. These models were implemented in the modular, interoperable, and commercially supported Umbra{reg_sign} simulation framework.

  2. Towards Real Time Simulation of Ship-Ship Interaction

    DEFF Research Database (Denmark)

    Lindberg, Ole; Bingham, Harry B.; Engsig-Karup, Allan Peter

    2012-01-01

    We present recent and preliminary work directed towards the development of a simplified, physics-based model for improved simulation of ship-ship interaction that can be used for both analysis and real-time computing (i.e. with real-time constraints due to visualization). The goal is to implement...... the model into a large maritime simulator for training of naval officers, in particular tug boat helmsmen. Tug boat simulators are used for training of communication and situation awareness during manoeuvre involved with towing of large vessels. A main objective of the work is to improve and enable more...... accurate (realistic) and much faster ship-wave and ship-ship simulations than are currently possible. The coupling of simulation with visualization should improve the visual experience such that it can be perceived as more realistic in training. Today the state-of-art in real-time ship-ship interaction...

  3. ELECTRON COOLING SIMULATION FOR ARBITRARY DISTRIBUTION OF ELECTRONS

    Energy Technology Data Exchange (ETDEWEB)

    SIDORIN,A.; SMIRNOV, A.; FEDOTOV, A.; BEN-ZVI, I.; KAYRAN, D.

    2007-09-10

    Typically, several approximations are being used in simulation of electron cooling process, for example, density distribution of electrons is calculated using an analytical expression and distribution in the velocity space is assumed to be Maxwellian in all degrees of freedom. However, in many applications, accurate description of the cooling process based on realistic distribution of electrons is very useful. This is especially true for a high-energy electron cooling system which requires bunched electron beam produced by an Energy Recovery Linac (Em). Such systems are proposed, for instance, for RHIC and electron - ion collider. To address unique features of the RHIC-I1 cooler, new algorithms were introduced in BETACOOL code which allow us to take into account local properties of electron distribution as well as calculate friction force for an arbitrary velocity distribution. Here, we describe these new numerical models. Results based on these numerical models are compared with typical approximations using electron distribution produced by simulations of electron bunch through ERL of RHIC-II cooler.

  4. Dynamical simulation of fluidized beds - hydrodynamically interacting granular particles

    CERN Document Server

    Ichiki, K; Ichiki, Kengo; Hayakawa, Hisao

    1995-01-01

    A numerical simulation of a gas-fluidized bed is performed without introduction of any empirical parameters. Realistic bubbles and slugs are observed in our simulation. It is found that the convective motion of particles is important for the bubbling phase and there is no convection in the slugging phase. From the simulation results, non-Gaussian distributions are found in the particle velocities and the relation between the deviation from Gaussian and the local density of particles is suggested. It is also shown that the power spectra of particle velocities obey power laws. A brief explanation on the relationship between the simulation results and the Kolmogorov scaling argument is discussed.

  5. Parallelization and automatic data distribution for nuclear reactor simulations

    Energy Technology Data Exchange (ETDEWEB)

    Liebrock, L.M. [Liebrock-Hicks Research, Calumet, MI (United States)

    1997-07-01

    Detailed attempts at realistic nuclear reactor simulations currently take many times real time to execute on high performance workstations. Even the fastest sequential machine can not run these simulations fast enough to ensure that the best corrective measure is used during a nuclear accident to prevent a minor malfunction from becoming a major catastrophe. Since sequential computers have nearly reached the speed of light barrier, these simulations will have to be run in parallel to make significant improvements in speed. In physical reactor plants, parallelism abounds. Fluids flow, controls change, and reactions occur in parallel with only adjacent components directly affecting each other. These do not occur in the sequentialized manner, with global instantaneous effects, that is often used in simulators. Development of parallel algorithms that more closely approximate the real-world operation of a reactor may, in addition to speeding up the simulations, actually improve the accuracy and reliability of the predictions generated. Three types of parallel architecture (shared memory machines, distributed memory multicomputers, and distributed networks) are briefly reviewed as targets for parallelization of nuclear reactor simulation. Various parallelization models (loop-based model, shared memory model, functional model, data parallel model, and a combined functional and data parallel model) are discussed along with their advantages and disadvantages for nuclear reactor simulation. A variety of tools are introduced for each of the models. Emphasis is placed on the data parallel model as the primary focus for two-phase flow simulation. Tools to support data parallel programming for multiple component applications and special parallelization considerations are also discussed.

  6. MR imaging of model drug distribution in simulated vitreous

    Directory of Open Access Journals (Sweden)

    Stein Sandra

    2015-09-01

    Full Text Available The in vitro and in vivo characterization of intravitreal injections plays an important role in developing innovative therapy approaches. Using the established vitreous model (VM and eye movement system (EyeMoS the distribution of contrast agents with different molecular weight was studied in vitro. The impact of the simulated age-related vitreal liquefaction (VL on drug distribution in VM was examined either with injection through the gel phase or through the liquid phase. For comparison the distribution was studied ex vivo in the porcine vitreous. The studies were performed in a magnetic resonance (MR scanner. As expected, with increasing molecular weight the diffusion velocity and the visual distribution of the injected substances decreased. Similar drug distribution was observed in VM and in porcine eye. VL causes enhanced convective flow and faster distribution in VM. Confirming the importance of the injection technique in progress of VL, injection through gelatinous phase caused faster distribution into peripheral regions of the VM than following injection through liquefied phase. VM and MR scanner in combination present a new approach for the in vitro characterization of drug release and distribution of intravitreal dosage forms.

  7. Envelope: interactive software for modeling and fitting complex isotope distributions

    Directory of Open Access Journals (Sweden)

    Sykes Michael T

    2008-10-01

    Full Text Available Abstract Background An important aspect of proteomic mass spectrometry involves quantifying and interpreting the isotope distributions arising from mixtures of macromolecules with different isotope labeling patterns. These patterns can be quite complex, in particular with in vivo metabolic labeling experiments producing fractional atomic labeling or fractional residue labeling of peptides or other macromolecules. In general, it can be difficult to distinguish the contributions of species with different labeling patterns to an experimental spectrum and difficult to calculate a theoretical isotope distribution to fit such data. There is a need for interactive and user-friendly software that can calculate and fit the entire isotope distribution of a complex mixture while comparing these calculations with experimental data and extracting the contributions from the differently labeled species. Results Envelope has been developed to be user-friendly while still being as flexible and powerful as possible. Envelope can simultaneously calculate the isotope distributions for any number of different labeling patterns for a given peptide or oligonucleotide, while automatically summing these into a single overall isotope distribution. Envelope can handle fractional or complete atom or residue-based labeling, and the contribution from each different user-defined labeling pattern is clearly illustrated in the interactive display and is individually adjustable. At present, Envelope supports labeling with 2H, 13C, and 15N, and supports adjustments for baseline correction, an instrument accuracy offset in the m/z domain, and peak width. Furthermore, Envelope can display experimental data superimposed on calculated isotope distributions, and calculate a least-squares goodness of fit between the two. All of this information is displayed on the screen in a single graphical user interface. Envelope supports high-quality output of experimental and calculated

  8. NUMERICAL SIMULATION OF ORIENTATION DISTRIBUTION FUNCTION OF CYLINDRICAL PARTICLE SUSPENSIONS

    Institute of Scientific and Technical Information of China (English)

    林建忠; 张凌新

    2002-01-01

    The orientation distribution function of cylindrical particle suspensions was deduced and numerically simulated, and an application was taken in a wedge-shaped flow field. The relationship between the orientation distribution function and particle orientation angles was obtained. The results show that comparing with the most probable angle distribution which comes to being in short time, the distribution of the steady state doesn' t vary much in range ; the main difference is the anti-clockwise rotation in the right and upper field, that is, particles rotate more at the points where the velocity gradients are larger.The most probable orientations are close to the direction of local streamlines. In the direction of streamlines, with poleradius decreasing, the most probable angles increase,but the angles between their orientations and the local streamlines decrease.

  9. System Engineering Strategy for Distributed Multi-Purpose Simulation Architectures

    Science.gov (United States)

    Bhula, Dlilpkumar; Kurt, Cindy Marie; Luty, Roger

    2007-01-01

    This paper describes the system engineering approach used to develop distributed multi-purpose simulations. The multi-purpose simulation architecture focuses on user needs, operations, flexibility, cost and maintenance. This approach was used to develop an International Space Station (ISS) simulator, which is called the International Space Station Integrated Simulation (ISIS)1. The ISIS runs unmodified ISS flight software, system models, and the astronaut command and control interface in an open system design that allows for rapid integration of multiple ISS models. The initial intent of ISIS was to provide a distributed system that allows access to ISS flight software and models for the creation, test, and validation of crew and ground controller procedures. This capability reduces the cost and scheduling issues associated with utilizing standalone simulators in fixed locations, and facilitates discovering unknowns and errors earlier in the development lifecycle. Since its inception, the flexible architecture of the ISIS has allowed its purpose to evolve to include ground operator system and display training, flight software modification testing, and as a realistic test bed for Exploration automation technology research and development.

  10. Development of MCNPX-ESUT computer code for simulation of neutron/gamma pulse height distribution

    Science.gov (United States)

    Abolfazl Hosseini, Seyed; Vosoughi, Naser; Zangian, Mehdi

    2015-05-01

    In this paper, the development of the MCNPX-ESUT (MCNPX-Energy Engineering of Sharif University of Technology) computer code for simulation of neutron/gamma pulse height distribution is reported. Since liquid organic scintillators like NE-213 are well suited and routinely used for spectrometry in mixed neutron/gamma fields, this type of detectors is selected for simulation in the present study. The proposed algorithm for simulation includes four main steps. The first step is the modeling of the neutron/gamma particle transport and their interactions with the materials in the environment and detector volume. In the second step, the number of scintillation photons due to charged particles such as electrons, alphas, protons and carbon nuclei in the scintillator material is calculated. In the third step, the transport of scintillation photons in the scintillator and lightguide is simulated. Finally, the resolution corresponding to the experiment is considered in the last step of the simulation. Unlike the similar computer codes like SCINFUL, NRESP7 and PHRESP, the developed computer code is applicable to both neutron and gamma sources. Hence, the discrimination of neutron and gamma in the mixed fields may be performed using the MCNPX-ESUT computer code. The main feature of MCNPX-ESUT computer code is that the neutron/gamma pulse height simulation may be performed without needing any sort of post processing. In the present study, the pulse height distributions due to a monoenergetic neutron/gamma source in NE-213 detector using MCNPX-ESUT computer code is simulated. The simulated neutron pulse height distributions are validated through comparing with experimental data (Gohil et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 664 (2012) 304-309.) and the results obtained from similar computer codes like SCINFUL, NRESP7 and Geant4. The simulated gamma pulse height distribution for a 137Cs

  11. Improving Project Management with Simulation and Completion Distribution Functions

    Science.gov (United States)

    Cates, Grant R.

    2004-01-01

    Despite the critical importance of project completion timeliness, management practices in place today remain inadequate for addressing the persistent problem of project completion tardiness. A major culprit in late projects is uncertainty, which most, if not all, projects are inherently subject to. This uncertainty resides in the estimates for activity durations, the occurrence of unplanned and unforeseen events, and the availability of critical resources. In response to this problem, this research developed a comprehensive simulation based methodology for conducting quantitative project completion time risk analysis. It is called the Project Assessment by Simulation Technique (PAST). This new tool enables project stakeholders to visualize uncertainty or risk, i.e. the likelihood of their project completing late and the magnitude of the lateness, by providing them with a completion time distribution function of their projects. Discrete event simulation is used within PAST to determine the completion distribution function for the project of interest. The simulation is populated with both deterministic and stochastic elements. The deterministic inputs include planned project activities, precedence requirements, and resource requirements. The stochastic inputs include activity duration growth distributions, probabilities for events that can impact the project, and other dynamic constraints that may be placed upon project activities and milestones. These stochastic inputs are based upon past data from similar projects. The time for an entity to complete the simulation network, subject to both the deterministic and stochastic factors, represents the time to complete the project. Repeating the simulation hundreds or thousands of times allows one to create the project completion distribution function. The Project Assessment by Simulation Technique was demonstrated to be effective for the on-going NASA project to assemble the International Space Station. Approximately $500

  12. Real-time modeling and simulation of distribution feeder and distributed resources

    Science.gov (United States)

    Singh, Pawan

    The analysis of the electrical system dates back to the days when analog network analyzers were used. With the advent of digital computers, many programs were written for power-flow and short circuit analysis for the improvement of the electrical system. Real-time computer simulations can answer many what-if scenarios in the existing or the proposed power system. In this thesis, the standard IEEE 13-Node distribution feeder is developed and validated on a real-time platform OPAL-RT. The concept and the challenges of the real-time simulation are studied and addressed. Distributed energy resources include some of the commonly used distributed generation and storage devices like diesel engine, solar photovoltaic array, and battery storage system are modeled and simulated on a real-time platform. A microgrid encompasses a portion of an electric power distribution which is located downstream of the distribution substation. Normally, the microgrid operates in paralleled mode with the grid; however, scheduled or forced isolation can take place. In such conditions, the microgrid must have the ability to operate stably and autonomously. The microgrid can operate in grid connected and islanded mode, both the operating modes are studied in the last chapter. Towards the end, a simple microgrid controller modeled and simulated on the real-time platform is developed for energy management and protection for the microgrid.

  13. Simulation of soot size distribution in an ethylene counterflow flame

    KAUST Repository

    Zhou, Kun

    2014-01-06

    Soot, an aggregate of carbonaceous particles produced during the rich combustion of fossil fuels, is an undesirable pollutant and health hazard. Soot evolution involves various dynamic processes: nucleation soot formation from polycyclic aromatic hydrocarbons (PAHs) condensation PAHs condensing on soot particle surface surface processes hydrogen-abstraction-C2H2-addition, oxidation coagulation two soot particles coagulating to form a bigger particle This simulation work investigates soot size distribution and morphology in an ethylene counterflow flame, using i). Chemkin with a method of moments to deal with the coupling between vapor consumption and soot formation; ii). Monte Carlo simulation of soot dynamics.

  14. Distribution System Optimization Planning Based on Plant Growth Simulation Algorithm

    Institute of Scientific and Technical Information of China (English)

    WANG Chun; CHENG Hao-zhong; HU Ze-chun; WANG Yi

    2008-01-01

    An approach for the integrated optimization of the construction/expansion capacity of high-voltage/medium-voltage (HV/MV) substations and the configuration of MV radial distribution network was presented using plant growth simulation algorithm (PGSA). In the optimization process, fixed costs correspondent to the investment in lines and substations and the variable costs associated to the operation of the system were considered under the constraints of branch capacity, substation capacity and bus voltage. The optimization variables considerably reduce the dimension of variables and speed up the process of optimizing. The effectiveness of the proposed approach was tested by a distribution system planning.

  15. Development of a Dynamically Configurable, Object-Oriented Framework for Distributed, Multi-modal Computational Aerospace Systems Simulation

    Science.gov (United States)

    Afjeh, Abdollah A.; Reed, John A.

    2003-01-01

    The following reports are presented on this project:A first year progress report on: Development of a Dynamically Configurable,Object-Oriented Framework for Distributed, Multi-modal Computational Aerospace Systems Simulation; A second year progress report on: Development of a Dynamically Configurable, Object-Oriented Framework for Distributed, Multi-modal Computational Aerospace Systems Simulation; An Extensible, Interchangeable and Sharable Database Model for Improving Multidisciplinary Aircraft Design; Interactive, Secure Web-enabled Aircraft Engine Simulation Using XML Databinding Integration; and Improving the Aircraft Design Process Using Web-based Modeling and Simulation.

  16. Does polar interaction influence medium viscosity? A computer simulation investigation using model liquids

    Indian Academy of Sciences (India)

    Snehasis Daschakraborty; Ranjit Biswas

    2012-07-01

    Molecular dynamics simulations of model liquids interacting via Lennard-Jones (L-J) and Stockmayer (SM) interactions have been carried out to explore the effects of the longer-ranged dipole-dipole interaction on solvent viscosity and diffusion. Switching on of the dipolar interaction at a fixed density and temperature has been found to increase the viscosity over that of the LJ liquid, the extent of increase being a few percent to as large as ∼60% depending on the magnitude of the solvent dipole moment used in the SM potential. The simulated translational and rotational diffusion coefficients show strong dipole moment and temperature dependences, eventhough effects of these parameters on solvent-solvent radial distribution function are moderate. Interestingly, a partial solute-solvent decoupling is observed when the simulated translational and rotational diffusion coefficients are connected to the simulated viscosity coefficients via the Stokes-Einstein (SE) and Stokes-Einstein-Debye (SED) relations. In the limit of large dipole moment, simulated self-part of the van Hove correlation function at intermediate times reveals a departure from the Gaussian distribution with particle displacement. This suggests that dynamic heterogeneity is one of the reasons for the departure of centre-of-mass diffusion from the SE relation in these model systems.

  17. Building Interactive Simulations in Web Pages without Programming.

    Science.gov (United States)

    Mailen Kootsey, J; McAuley, Grant; Bernal, Julie

    2005-01-01

    A software system is described for building interactive simulations and other numerical calculations in Web pages. The system is based on a new Java-based software architecture named NumberLinX (NLX) that isolates each function required to build the simulation so that a library of reusable objects could be assembled. The NLX objects are integrated into a commercial Web design program for coding-free page construction. The model description is entered through a wizard-like utility program that also functions as a model editor. The complete system permits very rapid construction of interactive simulations without coding. A wide range of applications are possible with the system beyond interactive calculations, including remote data collection and processing and collaboration over a network.

  18. Distributed Online Judge System for Interactive Theorem Provers

    Science.gov (United States)

    Mizuno, Takahisa; Nishizaki, Shin-ya

    2014-03-01

    In this paper, we propose a new software design of an online judge system for interactive theorem proving. The distinctive feature of this architecture is that our online judge system is distributed on the network and especially involves volunteer computing. In volunteers' computers, network bots (software robots) are executed and donate computational resources to the central host of the online judge system. Our proposed design improves fault tolerance and security. We gave an implementation to two different styles of interactive theorem prover, Coq and ACL2, and evaluated our proposed architecture. From the experiment on the implementation, we concluded that our architecture is efficient enough to be used practically.

  19. Distributed Online Judge System for Interactive Theorem Provers

    Directory of Open Access Journals (Sweden)

    Mizuno Takahisa

    2014-03-01

    Full Text Available In this paper, we propose a new software design of an online judge system for interactive theorem proving. The distinctive feature of this architecture is that our online judge system is distributed on the network and especially involves volunteer computing. In volunteers’ computers, network bots (software robots are executed and donate computational resources to the central host of the online judge system. Our proposed design improves fault tolerance and security. We gave an implementation to two different styles of interactive theorem prover, Coq and ACL2, and evaluated our proposed architecture. From the experiment on the implementation, we concluded that our architecture is efficient enough to be used practically.

  20. Novel simulation model for many-body multipole dispersion interactions

    Science.gov (United States)

    van der Hoef Paul, Martin A.; Madden, A.

    We present a novel simulation technique, within the framework of a molecular dynamics simulation, which accounts for both two- and three-body dispersion interactions, up to the triple-quadrupole interaction. This technique involves a unification of molecular dynamics and quantum-mechanical variational methods, in the spirit of the Car-Parrinello method. The advantage of this new method compared to existing techniques for simulating three-body dispersion forces, is that it allows for a consistent treatment of both dispersion damping and periodic boundary conditions at the pair and three-body level. The latter means that it would be possible, for the first time, to include many-body dispersion effects in the simulation of bulk properties of materials, without making use of effective pair potentials.

  1. Distributed Heterogeneous Simulation of a Hybrid-Electric Vehicle

    Science.gov (United States)

    2006-03-29

    operate as a generator to convert mechanical energy from the diesel t~nginc 01 from regenerative braking to electrical energy. A vehicle control module...Distributed Heterogeneous Simulation of a Hybrid- Electric Vehicle Ning Wu’, Curtis Rands t , Charles E. Lucas!, Eric A. Walters§, and Maher A...Masrurit US Army RDECOM-TARDEC, Warren, MI, 48397 Hybrid- electric military vehicles provide many advantages over conventional military vehicles powered

  2. Efficient simulation of strong system-environment interactions.

    Science.gov (United States)

    Prior, Javier; Chin, Alex W; Huelga, Susana F; Plenio, Martin B

    2010-07-30

    Multicomponent quantum systems in strong interaction with their environment are receiving increasing attention due to their importance in a variety of contexts, ranging from solid state quantum information processing to the quantum dynamics of biomolecular aggregates. Unfortunately, these systems are difficult to simulate as the system-bath interactions cannot be treated perturbatively and standard approaches are invalid or inefficient. Here we combine the time-dependent density matrix renormalization group with techniques from the theory of orthogonal polynomials to provide an efficient method for simulating open quantum systems, including spin-boson models and their generalizations to multicomponent systems.

  3. Efficient simulation of strong system-environment interactions

    CERN Document Server

    Prior, Javier; Huelga, Susana F; Plenio, Martin B

    2010-01-01

    Multi-component quantum systems in strong interaction with their environment are receiving increasing attention due to their importance in a variety of contexts, ranging from solid state quantum information processing to the quantum dynamics of bio-molecular aggregates. Unfortunately, these systems are difficult to simulate as the system-bath interactions cannot be treated perturbatively and standard approaches are invalid or inefficient. Here we combine the time dependent density matrix renormalization group methods with techniques from the theory of orthogonal polynomials to provide an efficient method for simulating open quantum systems, including spin-boson models and their generalisations to multi-component systems.

  4. A trophallaxis inspired model for distributed transport between randomly interacting agents

    CERN Document Server

    Gräwer, Johannes; Mazza, Marco G; Katifori, Eleni

    2016-01-01

    A trophallaxis inspired model for distributed transport between randomly interacting agents Trophallaxis, the regurgitation and mouth to mouth transfer of liquid food between members of eusocial insect societies, is an important process that allows the fast and efficient dissemination of food in the colony. Trophallactic systems are typically treated as a network of agent interactions. This approach, though valuable, does not easily lend itself to analytic predictions. In this work we consider a simple trophallactic system of randomly interacting agents with finite carrying capacity, and calculate analytically and via a series of simulations the global food intake rate for the whole colony as well as observables describing how uniformly the food is distributed within the nest. Our work serves as a stepping stone to describing the collective properties of more complex trophallactic systems, such as those including division of labor between foragers and workers.

  5. Simulated CONUS Flash Flood Climatologies from Distributed Hydrologic Models

    Science.gov (United States)

    Flamig, Z.; Gourley, J. J.; Vergara, H. J.; Kirstetter, P. E.; Hong, Y.

    2016-12-01

    This study will describe a CONUS flash flood climatology created over the period from 2002 through 2011. The MRMS reanalysis precipitation dataset was used as forcing into the Ensemble Framework For Flash Flood Forecasting (EF5). This high resolution 1-sq km 5-minute dataset is ideal for simulating flash floods with a distributed hydrologic model. EF5 features multiple water balance components including SAC-SMA, CREST, and a hydrophobic model all coupled with kinematic wave routing. The EF5/SAC-SMA and EF5/CREST water balance schemes were used for the creation of dual flash flood climatologies based on the differing water balance principles. For the period from 2002 through 2011 the daily maximum streamflow, unit streamflow, and time of peak streamflow was stored along with the minimum soil moisture. These variables are used to describe the states of the soils right before a flash flood event and the peak streamflow that was simulated during the flash flood event. The results will be shown, compared and contrasted. The resulting model simulations will be verified on basins less than 1,000-sq km with USGS gauges to ensure the distributed hydrologic models are reliable. The results will also be compared spatially to Storm Data flash flood event observations to judge the degree of agreement between the simulated climatologies and observations.

  6. FLUKA Monte Carlo Simulations about Cosmic Rays Interactions with Kaidun Meteorite

    Directory of Open Access Journals (Sweden)

    Turgay Korkut

    2013-01-01

    Full Text Available An asteroid called Kaidun fell on December 3, 1980, in Yemen (15° 0′N, 48° 18′E. Investigations on this large-sized meteorite are ongoing today. In this paper, interactions between cosmic rays-earth atmosphere and cosmic rays-Kaidun meteorite were modeled using a cosmic ray generator FLUKA Monte Carlo code. Isotope distributions and produced particles were given after these interactions. Also, simulation results were compared for these two types of interactions.

  7. Computer Simulation of Effect of Intergrain Exchange Interaction on Magnetic Properties of Nanocomposite Magnets

    Institute of Scientific and Technical Information of China (English)

    Fukunaga H; Mukaino H

    2004-01-01

    Effects of the intergrain exchange interaction on magnetic properties of nanocomposite magnets were investigated by using the computer simulation based on the micromagnetic theory. The simulation was carried out under the assumptions that the strength of the intergrain exchange interaction is weaker than that of the intragrain exchange interaction, that inhomogeneous nanostructures result in the distribution of the strength of the intergrain exchange interaction, and that there exists nonmagnetic intergranular phase(NMIP) between grain boundaries. The distribution of the strength of the intergrain exchange interaction was simulated by the lognormal distribution with the standard deviation of σ.The calculations for Nd2Fe14B/α-Fe nanocomposite magnets reveal that a suitably weak intergrain exchange interaction and small grain size enable us to improve magnetic properties. It is also found that a Nd2Fe14B/α-Fe nanocomposite magnet has a potential of a(BH)max value exceeding 300 kJ·m-3. On the other hand, the calculations for Nd2Fe14B/Fe3B nanocomposite magnets reveal that the distribution of the strength of the intergrain exchange interaction deteriorates magnetic properties significantly. Particularly, this tendency is remarkable, when the grain size L is larger than its optimum value, 11 nm. The existence of nonmagnetic boundary layers accelerats this tendency. At σ=0.2, the calculated demagnetization curve for the model magnet composed of Nd2Fe14B(36%)/Fe3B(54%)/NMIP(10%)(Valume fraction) grains(L=15 nm) agrees with that obtained experimentally for a Nd2Fe14B/Fe3B nanocomposite magnet. These results suggest importance of refinement of grain size, suppression of a nonmagnetic intergranular phase, and preparation of homogeneous nanostructure for superior magnetic properties.

  8. Parallel and distributed processing in power system simulation and control

    Energy Technology Data Exchange (ETDEWEB)

    Falcao, Djalma M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1994-12-31

    Recent advances in computer technology will certainly have a great impact in the methodologies used in power system expansion and operational planning as well as in real-time control. Parallel and distributed processing are among the new technologies that present great potential for application in these areas. Parallel computers use multiple functional or processing units to speed up computation while distributed processing computer systems are collection of computers joined together by high speed communication networks having many objectives and advantages. The paper presents some ideas for the use of parallel and distributed processing in power system simulation and control. It also comments on some of the current research work in these topics and presents a summary of the work presently being developed at COPPE. (author) 53 refs., 2 figs.

  9. Simulation of flame-vortex interaction using detailed and reduced

    Energy Technology Data Exchange (ETDEWEB)

    Hilka, M. [Gaz de France (GDF), 75 - Paris (France); Veynante, D. [Ecole Centrale de Paris, Laboratoire EM2C. CNRS, 92 - Chatenay-Malabry (France); Baum, M. [CERFACS (France); Poinsot, T.J. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France). Institut de Mecanique des Fluides de Toulouse

    1996-12-31

    The interaction between a pair of counter-rotating vortices and a lean premixed CH{sub 4}/O{sub 2}/N{sub 2} flame ({Phi} = + 0.55) has been studied by direct numerical simulations using detailed and reduced chemical reaction schemes. Results from the complex chemistry simulation are discussed with respect to earlier experiments and differences in the simulations using detailed and reduces chemistry are investigated. Transient evolutions of the flame surface and the total heat release rate are compared and modifications in the evolution of the local flame structure are displayed. (authors) 22 refs.

  10. Distributed and interactive visual analysis of omics data.

    Science.gov (United States)

    Farag, Yehia; Berven, Frode S; Jonassen, Inge; Petersen, Kjell; Barsnes, Harald

    2015-11-01

    The amount of publicly shared proteomics data has grown exponentially over the last decade as the solutions for sharing and storing the data have improved. However, the use of the data is often limited by the manner of which it is made available. There are two main approaches: download and inspect the proteomics data locally, or interact with the data via one or more web pages. The first is limited by having to download the data and thus requires local computational skills and resources, while the latter most often is limited in terms of interactivity and the analysis options available. A solution is to develop web-based systems supporting distributed and fully interactive visual analysis of proteomics data. The use of a distributed architecture makes it possible to perform the computational analysis at the server, while the results of the analysis can be displayed via a web browser without the need to download the whole dataset. Here the challenges related to developing such systems for omics data will be discussed. Especially how this allows for multiple connected interactive visual displays of omics dataset in a web-based setting, and the benefits this provide for computational analysis of proteomics data.This article is part of a Special Issue entitled: Computational Proteomics.

  11. Biotic Interactions Shape the Ecological Distributions of Staphylococcus Species

    Directory of Open Access Journals (Sweden)

    Erik K. Kastman

    2016-10-01

    Full Text Available Many metagenomic sequencing studies have observed the presence of closely related bacterial species or genotypes in the same microbiome. Previous attempts to explain these patterns of microdiversity have focused on the abiotic environment, but few have considered how biotic interactions could drive patterns of microbiome diversity. We dissected the patterns, processes, and mechanisms shaping the ecological distributions of three closely related Staphylococcus species in cheese rind biofilms. Paradoxically, the most abundant species (S. equorum is the slowest colonizer and weakest competitor based on growth and competition assays in the laboratory. Through in vitro community reconstructions, we determined that biotic interactions with neighboring fungi help resolve this paradox. Species-specific stimulation of the poor competitor by fungi of the genus Scopulariopsis allows S. equorum to dominate communities in vitro as it does in situ. Results of comparative genomic and transcriptomic experiments indicate that iron utilization pathways, including a homolog of the S. aureus staphyloferrin B siderophore operon pathway, are potential molecular mechanisms underlying Staphylococcus-Scopulariopsis interactions. Our integrated approach demonstrates that fungi can structure the ecological distributions of closely related bacterial species, and the data highlight the importance of bacterium-fungus interactions in attempts to design and manipulate microbiomes.

  12. Biotic Interactions Shape the Ecological Distributions of Staphylococcus Species.

    Science.gov (United States)

    Kastman, Erik K; Kamelamela, Noelani; Norville, Josh W; Cosetta, Casey M; Dutton, Rachel J; Wolfe, Benjamin E

    2016-10-18

    Many metagenomic sequencing studies have observed the presence of closely related bacterial species or genotypes in the same microbiome. Previous attempts to explain these patterns of microdiversity have focused on the abiotic environment, but few have considered how biotic interactions could drive patterns of microbiome diversity. We dissected the patterns, processes, and mechanisms shaping the ecological distributions of three closely related Staphylococcus species in cheese rind biofilms. Paradoxically, the most abundant species (S. equorum) is the slowest colonizer and weakest competitor based on growth and competition assays in the laboratory. Through in vitro community reconstructions, we determined that biotic interactions with neighboring fungi help resolve this paradox. Species-specific stimulation of the poor competitor by fungi of the genus Scopulariopsis allows S. equorum to dominate communities in vitro as it does in situ Results of comparative genomic and transcriptomic experiments indicate that iron utilization pathways, including a homolog of the S. aureus staphyloferrin B siderophore operon pathway, are potential molecular mechanisms underlying Staphylococcus-Scopulariopsis interactions. Our integrated approach demonstrates that fungi can structure the ecological distributions of closely related bacterial species, and the data highlight the importance of bacterium-fungus interactions in attempts to design and manipulate microbiomes. Decades of culture-based studies and more recent metagenomic studies have demonstrated that bacterial species in agriculture, medicine, industry, and nature are unevenly distributed across time and space. The ecological processes and molecular mechanisms that shape these distributions are not well understood because it is challenging to connect in situ patterns of diversity with mechanistic in vitro studies in the laboratory. Using tractable cheese rind biofilms and a focus on coagulase-negative staphylococcus (CNS

  13. Brownian dynamics simulations of a flexible polymer chain which includes continuous resistance and multibody hydrodynamic interactions

    Science.gov (United States)

    Butler, Jason E.; Shaqfeh, Eric S. G.

    2005-01-01

    Using methods adapted from the simulation of suspension dynamics, we have developed a Brownian dynamics algorithm with multibody hydrodynamic interactions for simulating the dynamics of polymer molecules. The polymer molecule is modeled as a chain composed of a series of inextensible, rigid rods with constraints at each joint to ensure continuity of the chain. The linear and rotational velocities of each segment of the polymer chain are described by the slender-body theory of Batchelor [J. Fluid Mech. 44, 419 (1970)]. To include hydrodynamic interactions between the segments of the chain, the line distribution of forces on each segment is approximated by making a Legendre polynomial expansion of the disturbance velocity on the segment, where the first two terms of the expansion are retained in the calculation. Thus, the resulting linear force distribution is specified by a center of mass force, couple, and stresslet on each segment. This method for calculating the hydrodynamic interactions has been successfully used to simulate the dynamics of noncolloidal suspensions of rigid fibers [O. G. Harlen, R. R. Sundararajakumar, and D. L. Koch, J. Fluid Mech. 388, 355 (1999); J. E. Butler and E. S. G. Shaqfeh, J. Fluid Mech. 468, 204 (2002)]. The longest relaxation time and center of mass diffusivity are among the quantities calculated with the simulation technique. Comparisons are made for different levels of approximation of the hydrodynamic interactions, including multibody interactions, two-body interactions, and the "freely draining" case with no interactions. For the short polymer chains studied in this paper, the results indicate a difference in the apparent scaling of diffusivity with polymer length for the multibody versus two-body level of approximation for the hydrodynamic interactions.

  14. Cloud vertical distribution from radiosonde, remote sensing, and model simulations

    Science.gov (United States)

    Zhang, Jinqiang; Li, Zhanqing; Chen, Hongbin; Yoo, Hyelim; Cribb, Maureen

    2014-08-01

    Knowledge of cloud vertical structure is important for meteorological and climate studies due to the impact of clouds on both the Earth's radiation budget and atmospheric adiabatic heating. Yet it is among the most difficult quantities to observe. In this study, we develop a long-term (10 years) radiosonde-based cloud profile product over the Southern Great Plains and along with ground-based and space-borne remote sensing products, use it to evaluate cloud layer distributions simulated by the National Centers for Environmental Prediction global forecast system (GFS) model. The primary objective of this study is to identify advantages and limitations associated with different cloud layer detection methods and model simulations. Cloud occurrence frequencies are evaluated on monthly, annual, and seasonal scales. Cloud vertical distributions from all datasets are bimodal with a lower peak located in the boundary layer and an upper peak located in the high troposphere. In general, radiosonde low-level cloud retrievals bear close resemblance to the ground-based remote sensing product in terms of their variability and gross spatial patterns. The ground-based remote sensing approach tends to underestimate high clouds relative to the radiosonde-based estimation and satellite products which tend to underestimate low clouds. As such, caution must be exercised to use any single product. Overall, the GFS model simulates less low-level and more high-level clouds than observations. In terms of total cloud cover, GFS model simulations agree fairly well with the ground-based remote sensing product. A large wet bias is revealed in GFS-simulated relative humidity fields at high levels in the atmosphere.

  15. Effective Student Learning of Fractions with an Interactive Simulation

    Science.gov (United States)

    Hensberry, Karina K. R.; Moore, Emily B.; Perkins, Katherine K.

    2015-01-01

    Computer technology, when coupled with reform-based teaching practices, has been shown to be an effective way to support student learning of mathematics. The quality of the technology itself, as well as how it is used, impacts how much students learn. Interactive simulations are dynamic virtual environments similar to virtual manipulatives that…

  16. I PASS: an interactive policy analysis simulation system.

    Science.gov (United States)

    Doug Olson; Con Schallau; Wilbur Maki

    1984-01-01

    This paper describes an interactive policy analysis simulation system(IPASS) that can be used to analyze the long-term economic and demographic effects of alternative forest resource management policies. The IPASS model is a dynamic analytical tool that forecasts growth and development of an economy. It allows the user to introduce changes in selected parameters based...

  17. Incorporating Context Dependency of Species Interactions in Species Distribution Models.

    Science.gov (United States)

    Lany, Nina K; Zarnetske, Phoebe L; Gouhier, Tarik C; Menge, Bruce A

    2017-07-01

    Species distribution models typically use correlative approaches that characterize the species-environment relationship using occurrence or abundance data for a single species. However, species distributions are determined by both abiotic conditions and biotic interactions with other species in the community. Therefore, climate change is expected to impact species through direct effects on their physiology and indirect effects propagated through their resources, predators, competitors, or mutualists. Furthermore, the sign and strength of species interactions can change according to abiotic conditions, resulting in context-dependent species interactions that may change across space or with climate change. Here, we incorporated the context dependency of species interactions into a dynamic species distribution model. We developed a multi-species model that uses a time-series of observational survey data to evaluate how abiotic conditions and species interactions affect the dynamics of three rocky intertidal species. The model further distinguishes between the direct effects of abiotic conditions on abundance and the indirect effects propagated through interactions with other species. We apply the model to keystone predation by the sea star Pisaster ochraceus on the mussel Mytilus californianus and the barnacle Balanus glandula in the rocky intertidal zone of the Pacific coast, USA. Our method indicated that biotic interactions between P. ochraceus and B. glandula affected B. glandula dynamics across >1000 km of coastline. Consistent with patterns from keystone predation, the growth rate of B. glandula varied according to the abundance of P. ochraceus in the previous year. The data and the model did not indicate that the strength of keystone predation by P. ochraceus varied with a mean annual upwelling index. Balanus glandula cover increased following years with high phytoplankton abundance measured as mean annual chlorophyll-a. M. californianus exhibited the same

  18. Favouritism in the motor system: social interaction modulates action simulation.

    Science.gov (United States)

    Kourtis, Dimitrios; Sebanz, Natalie; Knoblich, Günther

    2010-12-23

    The ability to anticipate others' actions is crucial for social interaction. It has been shown that this ability relies on motor areas of the human brain that are not only active during action execution and action observation, but also during anticipation of another person's action. Recording electroencephalograms during a triadic social interaction, we assessed whether activation of motor areas pertaining to the human mirror-neuron system prior to action observation depends on the social relationship between the actor and the observer. Anticipatory motor activation was stronger when participants expected an interaction partner to perform a particular action than when they anticipated that the same action would be performed by a third person they did not interact with. These results demonstrate that social interaction modulates action simulation.

  19. Real-time, interactive, visually updated simulator system for telepresence

    Science.gov (United States)

    Schebor, Frederick S.; Turney, Jerry L.; Marzwell, Neville I.

    1991-01-01

    Time delays and limited sensory feedback of remote telerobotic systems tend to disorient teleoperators and dramatically decrease the operator's performance. To remove the effects of time delays, key components were designed and developed of a prototype forward simulation subsystem, the Global-Local Environment Telerobotic Simulator (GLETS) that buffers the operator from the remote task. GLETS totally immerses an operator in a real-time, interactive, simulated, visually updated artificial environment of the remote telerobotic site. Using GLETS, the operator will, in effect, enter into a telerobotic virtual reality and can easily form a gestalt of the virtual 'local site' that matches the operator's normal interactions with the remote site. In addition to use in space based telerobotics, GLETS, due to its extendable architecture, can also be used in other teleoperational environments such as toxic material handling, construction, and undersea exploration.

  20. Simulation of chemical kinetics in sodium-concrete interactions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Sodium-concrete interaction is a key safety-related issue in safety analysis of liquid metal cooled fast breeder reactors (LMFBRs). The chemical kinetics model is a key component of the sodium-concrete interaction model. Conservation equations integrated in sodium-concrete interaction model cannot be solved without a set of relationships that couple the equations together, and this may be done by the chemical kinetics model. Simultaneously,simulation of chemical kinetics is difficult due to complexity of the mechanism of chemical reactions between sodium and concrete. This paper describes the chemical kinetics simulation under some hypotheses. The chemical kinetics model was integrated with the conservation equations to form a computer code. Penetration depth, penetration rate,hydrogen flux, reaction heat, etc. can be provided by this code. Theoretical models and computational procedure were recounted in detail. Good agreements of an overall transient behavior were obtained in a series of sodium-concrete interaction experiment analysis. Comparison between analytical and experimental results showed that the chemical kinetics model presented in this paper was creditable and reasonable for simulating the sodium-concrete interactions.

  1. Graph model of behavior simulator. [Interactive simulator developed as part of UCLA SARA system

    Energy Technology Data Exchange (ETDEWEB)

    Razouk, R.R.; Estrin, G.

    1966-01-01

    An interactive simulator developed at UCLA as part of the SARA system is described. This simulator, in conjunction with other design tools of the SARA system, allows the user to model the behavior of the system being designed at various levels of detail. The models which drive the simulator are control graphs and associated data graphs. The simulator uses the control graph to express synchronization of sequences of events. Initiation of any control node triggers the simulator to call on the data graph model to provide interpretation of a process at a desired level of abstraction. The simulator gives the user the capability to examine, or modify, the state of the control and data graphs during a simulation. 8 figures.

  2. Simulation of granular packing of frictional cohesive particles with Gaussian size distribution

    Science.gov (United States)

    Jia, Tao; Gao, Di

    2016-09-01

    The granular packing of frictional cohesive particles with Gaussian distribution is investigated based on distinct element method. Different sliding frictional coefficients are considered in the simulation. Due to the inelastic collision between the particles, the agglomeration of the particles occurs and the packing structure is formed finally. The range of the diameter of the particle is between 50 and 100 μm, and the distribution of the particle diameter is Gaussian. The inelastic interaction is caused by the viscoelastic force and the frictional force. The internal structure of the granular matter is quantified by the coordination number, packing density, and the force distribution. It is found that the increase in the sliding frictional coefficient looses the packing structure, and the distribution range of the contact force is larger than that of the van der Waals force.

  3. Developing Models for Embodied Learning with Live Interactive Simulations

    DEFF Research Database (Denmark)

    Gjedde, Lisa

    2014-01-01

    Live simulations may offer a natural form of multimodal learning through embodied action, which can be engaging to a variety of learners and provide a platform for inclusion of special needs learners across the classroom. In this approach to interactive learning, the subject matter is embedded...... learning design is available that provides for interactive and embodied learning, which appeals to the segment of boys that are often difficult to motivate with ordinary uni-modal teaching methods. The paper will present preliminary results from an action research project carried out in collaboration...... with a municipal secondary school. It has been part of a large scale research project, which has implemented models for embodied learning through narrative role-play games and interactive simulations....

  4. An online interactive simulation system for medical imaging education.

    Science.gov (United States)

    Dikshit, Aditya; Wu, Dawei; Wu, Chunyan; Zhao, Weizhao

    2005-09-01

    This report presents a recently developed web-based medical imaging simulation system for teaching students or other trainees who plan to work in the medical imaging field. The increased importance of computer and information technology widely applied to different imaging techniques in clinics and medical research necessitates a comprehensive medical imaging education program. A complete tutorial of simulations introducing popular imaging modalities, such as X-ray, MRI, CT, ultrasound and PET, forms an essential component of such an education. Internet technologies provide a vehicle to carry medical imaging education online. There exist a number of internet-based medical imaging hyper-books or online documentations. However, there are few providing interactive computational simulations. We focus on delivering knowledge of the physical principles and engineering implementation of medical imaging techniques through an interactive website environment. The online medical imaging simulation system presented in this report outlines basic principles underlying different imaging techniques and image processing algorithms and offers trainees an interactive virtual laboratory. For education purposes, this system aims to provide general understanding of each imaging modality with comprehensive explanations, ample illustrations and copious references as its thrust, rather than complex physics or detailed math. This report specifically describes the development of the tutorial for commonly used medical imaging modalities. An internet-accessible interface is used to simulate various imaging algorithms with user-adjustable parameters. The tutorial is under the MATLAB Web Server environment. Macromedia Director MX is used to develop interactive animations integrating theory with graphic-oriented simulations. HTML and JavaScript are used to enable a user to explore these modules online in a web browser. Numerous multiple choice questions, links and references for advanced study are

  5. Spatially varying color distributions for interactive multilabel segmentation.

    Science.gov (United States)

    Nieuwenhuis, Claudia; Cremers, Daniel

    2013-05-01

    We propose a method for interactive multilabel segmentation which explicitly takes into account the spatial variation of color distributions. To this end, we estimate a joint distribution over color and spatial location using a generalized Parzen density estimator applied to each user scribble. In this way, we obtain a likelihood for observing certain color values at a spatial coordinate. This likelihood is then incorporated in a Bayesian MAP estimation approach to multiregion segmentation which in turn is optimized using recently developed convex relaxation techniques. These guarantee global optimality for the two-region case (foreground/background) and solutions of bounded optimality for the multiregion case. We show results on the GrabCut benchmark, the recently published Graz benchmark, and on the Berkeley segmentation database which exceed previous approaches such as GrabCut, the Random Walker, Santner's approach, TV-Seg, and interactive graph cuts in accuracy. Our results demonstrate that taking into account the spatial variation of color models leads to drastic improvements for interactive image segmentation.

  6. Simulation of 2D Fields of Raindrop Size Distributions

    Science.gov (United States)

    Berne, A.; Schleiss, M.; Uijlenhoet, R.

    2008-12-01

    The raindrop size distribution (DSD hereafter) is of primary importance for quantitative applications of weather radar measurements. The radar reflectivity~Z (directly measured by radar) is related to the power backscattered by the ensemble of hydrometeors within the radar sampling volume. However, the rain rate~R (the flux of water to the surface) is the variable of interest for many applications (hydrology, weather forecasting, air traffic for example). Usually, radar reflectivity is converted into rain rate using a power law such as Z=aRb. The coefficients a and b of the Z-R relationship depend on the DSD. The variability of the DSD in space and time has to be taken into account to improve radar rain rate estimates. Therefore, the ability to generate a large number of 2D fields of DSD which are statistically homogeneous provides a very useful simulation framework that nicely complements experimental approaches based on DSD data, in order to investigate radar beam propagation through rain as well as radar retrieval techniques. The proposed approach is based on geostatistics for structural analysis and stochastic simulation. First, the DSD is assumed to follow a gamma distribution. Hence a 2D field of DSDs can be adequately described as a 2D field of a multivariate random function consisting of the three DSD parameters. Such fields are simulated by combining a Gaussian anamorphosis and a multivariate Gaussian random field simulation algorithm. Using the (cross-)variogram models fitted on data guaranties that the spatial structure of the simulated fields is consistent with the observed one. To assess its validity, the proposed method is applied to data collected during intense Mediterranean rainfall. As only time series are available, Taylor's hypothesis is assumed to convert time series in 1D range profile. Moreover, DSD fields are assumed to be isotropic so that the 1D structure can be used to simulate 2D fields. A large number of 2D fields of DSD parameters are

  7. Star formation rates and mass distributions in interacting galaxies

    CERN Document Server

    Kapferer, W; Schindler, S; Van Kampen, E

    2005-01-01

    We present a systematic investigation of the star formation rate (hereafter SFR) in interacting disk galaxies. We determine the dependence of the overall SFR on different spatial alignments and impact parameters of more than 50 different configurations in combined N-body/hydrodynamic simulations. We also show mass profiles of the baryonic components. We find that galaxy-galaxy interactions can enrich the surrounding intergalatic medium with metals very efficiently up to distances of several 100 kpc. This enrichment can be explained in terms of indirect processes like thermal driven galactic winds or direct processes like 'kinetic' spreading of baryonic matter. In the case of equal mass mergers the direct -kinetic- redistribution of gaseous matter (after 5 Gyr) is less efficient than the environmental enrichment of the same isolated galaxies by a galactic wind. In the case of non-equal mass mergers however, the direct -kinetic- process dominates the redistribution of gaseous matter. Compared to the isolated sy...

  8. Interaction between charged nanoparticles and vesicles: coarse-grained molecular dynamics simulations.

    Science.gov (United States)

    Liu, Linying; Zhang, Jianhua; Zhao, Xiaowei; Mao, Zheng; Liu, Na; Zhang, Youyu; Liu, Qing Huo

    2016-11-23

    An enhanced understanding of the interactions between charged nanoparticles (CNPs) and a curved vesicle membrane may have important implications for the design of nanocarrier agents and drug delivery systems. In this work, coarse-grained molecular dynamics (CGMD) simulations of the CNPs with vesicles were performed to evaluate the effects of hydrophobicity, surface charge density and distribution on the curved vesicle membrane. The simulations reveal that there exist four distinct modes (insertion, repulsion, adhesion, and penetration) in the CNP-vesicle interaction. In contrast to previous studies on a planar membrane, the interactions of CNPs and a curved vesicle membrane show some novel properties. CNPs with low surface charge density (or neutral ones) can penetrate into the interior of the vesicle membrane more easily because of the increased membrane tension. The asymmetry between two leaflets of the membrane induces different interaction strengths of the negatively CNPs with the outer and inner leaflets. After penetration, the negatively CNPs prefer to stay close to the inner leaflet inside the vesicle where CNPs have stronger interactions with their surroundings. In the present work, we analyze the detailed mechanism of CNP's spontaneous penetration into vesicles, which is rarely mentioned in previous simulations. Moreover, we found that the negatively CNPs with the same surface charge density but different distribution result in different modes: the homogeneous mode is more likely to adsorb on the vesicle surface while the inhomogeneous mode tends to be more penetrable. In addition, the flip-flop phenomenon of the lipid membrane and the exchanging of water in or out of the vesicle were observed during penetration. Our results demonstrate that the electrostatic effect plays an essential role in the interaction between CNPs and vesicles. These findings suggest a way of controlling the CNP-vesicle interaction by coupling the hydrophobic properties, surface

  9. CORBASec Used to Secure Distributed Aerospace Propulsion Simulations

    Science.gov (United States)

    Blaser, Tammy M.

    2003-01-01

    The NASA Glenn Research Center and its industry partners are developing a Common Object Request Broker (CORBA) Security (CORBASec) test bed to secure their distributed aerospace propulsion simulations. Glenn has been working with its aerospace propulsion industry partners to deploy the Numerical Propulsion System Simulation (NPSS) object-based technology. NPSS is a program focused on reducing the cost and time in developing aerospace propulsion engines. It was developed by Glenn and is being managed by the NASA Ames Research Center as the lead center reporting directly to NASA Headquarters' Aerospace Technology Enterprise. Glenn is an active domain member of the Object Management Group: an open membership, not-for-profit consortium that produces and manages computer industry specifications (i.e., CORBA) for interoperable enterprise applications. When NPSS is deployed, it will assemble a distributed aerospace propulsion simulation scenario from proprietary analytical CORBA servers and execute them with security afforded by the CORBASec implementation. The NPSS CORBASec test bed was initially developed with the TPBroker Security Service product (Hitachi Computer Products (America), Inc., Waltham, MA) using the Object Request Broker (ORB), which is based on the TPBroker Basic Object Adaptor, and using NPSS software across different firewall products. The test bed has been migrated to the Portable Object Adaptor architecture using the Hitachi Security Service product based on the VisiBroker 4.x ORB (Borland, Scotts Valley, CA) and on the Orbix 2000 ORB (Dublin, Ireland, with U.S. headquarters in Waltham, MA). Glenn, GE Aircraft Engines, and Pratt & Whitney Aircraft are the initial industry partners contributing to the NPSS CORBASec test bed. The test bed uses Security SecurID (RSA Security Inc., Bedford, MA) two-factor token-based authentication together with Hitachi Security Service digital-certificate-based authentication to validate the various NPSS users. The test

  10. Simulation of emission tomography using grid middleware for distributed computing.

    Science.gov (United States)

    Thomason, M G; Longton, R F; Gregor, J; Smith, G T; Hutson, R K

    2004-09-01

    SimSET is Monte Carlo simulation software for emission tomography. This paper describes a simple but effective scheme for parallel execution of SimSET using NetSolve, a client-server system for distributed computation. NetSolve (version 1.4.1) is "grid middleware" which enables a user (the client) to run specific computations remotely and simultaneously on a grid of networked computers (the servers). Since the servers do not have to be identical machines, computation may take place in a heterogeneous environment. To take advantage of diversity in machines and their workloads, a client-side scheduler was implemented for the Monte Carlo simulation. The scheduler partitions the total decay events by taking into account the inherent compute-speeds and recent average workloads, i.e., the scheduler assigns more decay events to processors expected to give faster service and fewer decay events to those expected to give slower service. When compute-speeds and sustained workloads are taken into account, the speed-up is essentially linear in the number of equivalent "maximum-service" processors. One modification in the SimSET code (version 2.6.2.3) was made to ensure that the total number of decay events specified by the user is maintained in the distributed simulation. No other modifications in the standard SimSET code were made. Each processor runs complete SimSET code for its assignment of decay events, independently of others running simultaneously. Empirical results are reported for simulation of a clinical-quality lung perfusion study.

  11. Simulation study of territory size distributions in subterranean termites.

    Science.gov (United States)

    Jeon, Wonju; Lee, Sang-Hee

    2011-06-21

    In this study, on the basis of empirical data, we have simulated the foraging tunnel patterns of two subterranean termites, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar), using a two-dimensional model. We have defined a territory as a convex polygon containing a tunnel pattern and explored the effects of competition among termite territory colonies on the territory size distribution in the steady state that was attained after a sufficient simulation time. In the model, territorial competition was characterized by a blocking probability P(block) that quantitatively describes the ease with which a tunnel stops its advancement when it meets another tunnel; higher P(block) values imply easier termination. In the beginning of the simulation run, N=10, 20,…,100 territory seeds, representing the founding pair, were randomly distributed on a square area. When the territory density was less (N=20), the differences in the territory size distributions for different P(block) values were small because the territories had sufficient space to grow without strong competitions. Further, when the territory density was higher (N>20), the territory sizes increased in accordance with the combinational effect of P(block) and N. In order to understand these effects better, we introduced an interference coefficient γ. We mathematically derived γ as a function of P(block) and N: γ(N,P(block))=a(N)P(block)/(P(block)+b(N)). a(N) and b(N) are functions of N/(N+c) and d/(N+c), respectively, and c and d are constants characterizing territorial competition. The γ function is applicable to characterize the territoriality of various species and increases with both the P(block) values and N; higher γ values imply higher limitations of the network growth. We used the γ function, fitted the simulation results, and determined the c and d values. In addition, we have briefly discussed the predictability of the present model by comparing it with our previous lattice model

  12. Brownian dynamics simulations with hard-body interactions: Spherical particles

    CERN Document Server

    Behringer, Hans; 10.1063/1.4761827

    2012-01-01

    A novel approach to account for hard-body interactions in (overdamped) Brownian dynamics simulations is proposed for systems with non-vanishing force fields. The scheme exploits the analytically known transition probability for a Brownian particle on a one-dimensional half-line. The motion of a Brownian particle is decomposed into a component that is affected by hard-body interactions and into components that are unaffected. The hard-body interactions are incorporated by replacing the affected component of motion by the evolution on a half-line. It is discussed under which circumstances this approach is justified. In particular, the algorithm is developed and formulated for systems with space-fixed obstacles and for systems comprising spherical particles. The validity and justification of the algorithm is investigated numerically by looking at exemplary model systems of soft matter, namely at colloids in flow fields and at protein interactions. Furthermore, a thorough discussion of properties of other heurist...

  13. Distributed interacted multisensor joint probabilistic data association algorithm based on D-S theory

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to resolve the multisensor multiplied maneuvering target tracking problem, this paper presents a distributed interacted multiple model multisensor joint probabilistic data association algorithm (DIMM-MSJPDA). First of all, the interacted multiple model joint probabilistic data association algorithm is applied to each sensor, and then the state estimation, estimation covariance, model probability, combined innovation, innovation covariance are delivered to the fusion center. Then, the tracks from each sensor are correlated and the D-S evidence theory is used to gain the model probability of an identical target. Finally, the ultimate state estimation of each target is calculated according to the new model probability, and the state estimation is transmitted to each sensor. Simulations are designed to test the tracking performance of DIMM-MSJPDA algorithm. The results show that the use of DIMM-MSJPDA algorithm enables the distributed multisensor system to track multiplied maneuvering targets and its tracking performance is much better than that of IMMJPDA algorithm.

  14. Atomistic protein folding simulations on the submillisecond time scale using worldwide distributed computing.

    Science.gov (United States)

    Pande, Vijay S; Baker, Ian; Chapman, Jarrod; Elmer, Sidney P; Khaliq, Siraj; Larson, Stefan M; Rhee, Young Min; Shirts, Michael R; Snow, Christopher D; Sorin, Eric J; Zagrovic, Bojan

    2003-01-01

    Atomistic simulations of protein folding have the potential to be a great complement to experimental studies, but have been severely limited by the time scales accessible with current computer hardware and algorithms. By employing a worldwide distributed computing network of tens of thousands of PCs and algorithms designed to efficiently utilize this new many-processor, highly heterogeneous, loosely coupled distributed computing paradigm, we have been able to simulate hundreds of microseconds of atomistic molecular dynamics. This has allowed us to directly simulate the folding mechanism and to accurately predict the folding rate of several fast-folding proteins and polymers, including a nonbiological helix, polypeptide alpha-helices, a beta-hairpin, and a three-helix bundle protein from the villin headpiece. Our results demonstrate that one can reach the time scales needed to simulate fast folding using distributed computing, and that potential sets used to describe interatomic interactions are sufficiently accurate to reach the folded state with experimentally validated rates, at least for small proteins.

  15. Implementation of quantum key distribution network simulation module in the network simulator NS-3

    Science.gov (United States)

    Mehic, Miralem; Maurhart, Oliver; Rass, Stefan; Voznak, Miroslav

    2017-10-01

    As the research in quantum key distribution (QKD) technology grows larger and becomes more complex, the need for highly accurate and scalable simulation technologies becomes important to assess the practical feasibility and foresee difficulties in the practical implementation of theoretical achievements. Due to the specificity of the QKD link which requires optical and Internet connection between the network nodes, to deploy a complete testbed containing multiple network hosts and links to validate and verify a certain network algorithm or protocol would be very costly. Network simulators in these circumstances save vast amounts of money and time in accomplishing such a task. The simulation environment offers the creation of complex network topologies, a high degree of control and repeatable experiments, which in turn allows researchers to conduct experiments and confirm their results. In this paper, we described the design of the QKD network simulation module which was developed in the network simulator of version 3 (NS-3). The module supports simulation of the QKD network in an overlay mode or in a single TCP/IP mode. Therefore, it can be used to simulate other network technologies regardless of QKD.

  16. Interaction of Biofunctionalized Nanoparticles with Receptors on Cell Surfaces: MC Simulations

    Science.gov (United States)

    Dormidontova, Elena; Wang, Shihu

    2015-03-01

    One of the areas of active development of modern nanomedicine is drug/gene delivery and imaging application of nanoparticles functionalized by ligands, aptamers or antibodies capable of specific interactions with cell surface receptors. Being a complex multifunctional system different structural aspects of nanoparticles affect their interactions with cell surfaces and the surface properties of cells can be different (e.g. density, distribution and mobility of receptors). Computer simulations allow a systematic investigation of the influence of multiple factors and provide a unified platform for the comparison. Using Monte Carlo simulations we investigate the influence of the nanoparticle properties (nanoparticle size, polymer tether length, polydispersity, density, ligand energy, valence and density) on nanoparticle-cell surface interactions and make predictions regarding favorable nanoparticle design for achieving multiple ligand-receptor binding. We will also discuss the implications of nanoparticle design on the selectivity of attachment to cells with high receptor density while ``ignoring'' cells with a low density of receptors.

  17. Ion angular distribution simulation of the HEMP Thruster

    Science.gov (United States)

    Duras, Julia; Koch, Norbert; Kahnfeld, Daniel; Bandelow, Gunnar; Matthias, Paul; Lüskow, Karl Felix; Schneider, Ralf; Kemnitz, Stefan

    2016-10-01

    Ion angular current and energy distributions are important parameters for ion thrusters, which are typically measured at a few tens of centimetres to a few meters distance from thruster exit. However, fully kinetic Particle-in-Cell simulations are not able to simulate such domain sizes, due to high computational costs. Therefore, a parallelisation strategy of the code is presented to reduce computational time. To map diagnostics information from the domain boundary of the calculational domain to the positions of experimental diagnostics the concept of transfer functions is introduced. The calculated ion beam angular distributions in the plume region are quite sensitive to boundary conditions of the potential, possible additional source contributions, e.g. from secondary electron emission at vessel walls, and charge exchange collisions. This work was supported by the Bavarian State Ministry of Education Science and the Arts and the German Space Agency DLR. We also like to thank R. Heidemann from THALES Electron Devices GmbH, for interesting and stimulating discussions.

  18. CFD Simulation of Air Velocity Distribution in Occupied Livestock Buildings

    DEFF Research Database (Denmark)

    Svidt, Kjeld; Zhang, G.; Bjerg, B.

    In modem livestock buildings the design of the ventilation systems is important in order to obtain good air distribution. The use of Computational Fluid Dynamics for predicting the air flow and air quality makes it possible to include the effect of room geometry, equipment and occupants in the de......In modem livestock buildings the design of the ventilation systems is important in order to obtain good air distribution. The use of Computational Fluid Dynamics for predicting the air flow and air quality makes it possible to include the effect of room geometry, equipment and occupants...... in the design of ventilation systems. However, it is not appropriate to include the detailed geometry of a large group of lying or standing animals affecting the air flow in the building. It is necessary to have relatively simple models of the animals, which are easier to implement in the computer models....... In this study laboratory measurements in a ventilated test room with "pig simulators" are compared with CFD-simulations....

  19. Large-Scale Mass Distribution in the Illustris-Simulation

    CERN Document Server

    Haider, Markus; Vogelsberger, Mark; Genel, Shy; Springel, Volker; Torrey, Paul; Hernquist, Lars

    2015-01-01

    Observations at low redshifts thus far fail to account for all of the baryons expected in the Universe according to cosmological constraints. A large fraction of the baryons presumably resides in a thin and warm-hot medium between the galaxies, where they are difficult to observe due to their low densities and high temperatures. Cosmological simulations of structure formation can be used to verify this picture and provide quantitative predictions for the distribution of mass in different large-scale structure components. Here we study the distribution of baryons and dark matter at different epochs using data from the Illustris Simulation. We identify regions of different dark matter density with the primary constituents of large-scale structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift zero, we find that 49 % of the dark matter and 23 % of the baryons are within haloes. The filaments of the cosmic web host a further 45 % of the dark matter and 46 % of the baryons. The...

  20. Testing advanced driver assistance systems with the interactive driving simulator; Erprobung von Fahrerassistenzsystemen mit dem Interactive Driving Simulator

    Energy Technology Data Exchange (ETDEWEB)

    Friedrichs, A.; Grosse-Kappenberg, S.; Happe, J. [Zentrum fuer Lern- und Wissensmanagement und Lehrstuhl Informatik im Maschinenbau ZLW/IMA der RWTH Aachen (Germany)

    2005-07-01

    The Centre for Learning and Knowledge Management and Department of Computer Science in Engineering of the Technical University Aachen has developed a truck driving simulator which combines a driving simulation as well as traffic flow calculations to the interactive Driving Simulator (InDriveS). In real-time the effects of the driver's behaviour on the surrounding traffic are considered and vice versa. The integrative part of InDriveS is a software-in-the-loop and hardware-in-the-loop development environment. By means of this tool, all phases of development (Analysis, Design, Modelling, Simulation, Implementation as well as Testing and Evaluation) of new vehicle technologies, e.g. Information and Assistance Systems, can be realised in consideration of the road traffic and the driver's behaviour. (orig.)

  1. Numerical Simulation of Wave Interaction with Moving Net Structures

    DEFF Research Database (Denmark)

    Chen, Hao; Christensen, Erik Damgaard

    2015-01-01

    Fluid structure interaction is an important issue in designof many engineering systems including offshore fish cages. As a first step to develop a coupled CFD/FEM model, in the present study a moving porous media model has been developed in the open source library Open FOAM. The net structure...... was described as a sheet of porous media with prescribed rigid body motion and mesh motion was incorporated to conform the motion of the net. Free surface wave generation and absorption framework was also introduced to simulate wave interaction with moving net structures. The results showed that mesh motion...... with moving net structures....

  2. Blocking temperature of interacting magnetic nanoparticles with uniaxial and cubic anisotropies from Monte Carlo simulations

    Science.gov (United States)

    Russier, V.

    2016-07-01

    The low temperature behavior of densely packed interacting spherical single domain nanoparticles (MNP) is investigated by Monte Carlo simulations in the framework of an effective one spin model. The particles are distributed through a hard sphere like distribution with periodic boundary conditions and interact through the dipole dipole interaction (DDI) with an anisotropy energy including both cubic and uniaxial symmetry components. The cubic component is shown to play a sizable role on the value of the blocking temperature Tb only when the MNP easy axes are parallel to the cubic easy direction ([111] direction for a negative cubic anisotropy constant). The nature of the collective low temperature state, either ferromagnetic or spin glass like, is found to depend on the ratio of the anisotropy to the dipolar energies characterizing partly the disorder in the system.

  3. Simulations of the Hadamard Variance: Probability Distributions and Confidence Intervals.

    Science.gov (United States)

    Ashby, Neil; Patla, Bijunath

    2016-04-01

    Power-law noise in clocks and oscillators can be simulated by Fourier transforming a modified spectrum of white phase noise. This approach has been applied successfully to simulation of the Allan variance and the modified Allan variance in both overlapping and nonoverlapping forms. When significant frequency drift is present in an oscillator, at large sampling times the Allan variance overestimates the intrinsic noise, while the Hadamard variance is insensitive to frequency drift. The simulation method is extended in this paper to predict the Hadamard variance for the common types of power-law noise. Symmetric real matrices are introduced whose traces-the sums of their eigenvalues-are equal to the Hadamard variances, in overlapping or nonoverlapping forms, as well as for the corresponding forms of the modified Hadamard variance. We show that the standard relations between spectral densities and Hadamard variance are obtained with this method. The matrix eigenvalues determine probability distributions for observing a variance at an arbitrary value of the sampling interval τ, and hence for estimating confidence in the measurements.

  4. Wave optics approach for incoherent imaging simulation through distributed turbulence

    Science.gov (United States)

    Underwood, Thomas A.; Voelz, David G.

    2013-09-01

    An approach is presented for numerically simulating incoherent imaging using coherent wave optics propagation methods. The approach employs averaging of irradiance from uncorrelated coherent waves to produce incoherent results. Novel aspects of the method include 1) the exploitation of a spatial windowing feature in the wave optics numerical propagator to limit the angular spread of the light and 2) a simple propagation scaling concept to avoid aliased field components after the focusing element. Classical linear systems theory is commonly used to simulate incoherent imaging when it is possible to incorporate aberrations and/or propagation medium characteristics into an optical transfer function (OTF). However, the technique presented here is useful for investigating situations such as "instantaneous" short-exposure imaging through distributed turbulence and phenomena like anisoplanatism that are not easily modeled with the typical linear systems theory. The relationships between simulation variables such as spatial sampling, source and aperture support, and intermediate focal plane are discussed and the requirement or benefits of choosing these in certain ways are demonstrated.

  5. APPLICATION OF INTERACTIVE ONLINE SIMULATIONS FOR DEMONSTRATION EXPERIMENT IN PHYSICS

    Directory of Open Access Journals (Sweden)

    Nina P. Dementievska

    2014-06-01

    Full Text Available Development of modern school physics experiment is related to the extensive use of ICT not only for data processing and visualization. Interactive computer simulation for processes and phenomena, developed by scientists and methodologists by the site Phet, helps to improve the physical demonstration experiment with the support of modern pedagogical technologies that change the traditional procedure to form students' understanding of the processes and phenomena, active cognitive activity. To study the influence of methods to integrate interactive computer simulations for better understanding the students' physical processes, phenomena and laws of the international community, teachers and Ukrainian scientists and teachers of physics have been involved. The aim of the article is to introduce the research results in the development and testing of individual components of educational technology in performing a physical experiment in secondary school.

  6. First-principles simulations of electrostatic interactions between dust grains

    CERN Document Server

    Itou, Hotaka; Hoshino, Masahiro

    2014-01-01

    We investigated the electrostatic interaction between two identical dust grains of an infinite mass immersed in homogeneous plasma by employing first-principles N-body simulations combined with the Ewald method. We specifically tested the possibility of an attractive force due to overlapping Debye spheres (ODSs), as was suggested by Resendes et al. (1998). Our simulation results demonstrate that the electrostatic interaction is repulsive and even stronger than the standard Yukawa potential. We showed that the measured electric field acting on the grain is highly consistent with a model electrostatic potential around a single isolated grain that takes into account a correction due to the orbital motion limited theory. Our result is qualitatively consistent with the counterargument suggested by Markes and Williams (2000), indicating the absence of the ODS attractive force.

  7. Developing Models for Embodied Learning with Live Interactive Simulations

    DEFF Research Database (Denmark)

    Gjedde, Lisa

    2014-01-01

    Live simulations may offer a natural form of multimodal learning through embodied action, which can be engaging to a variety of learners and provide a platform for inclusion of special needs learners across the classroom. In this approach to interactive learning, the subject matter is embedded...... in narrative Role Play Games. Through this platform which combines the narrative framework with a game-driven approach an analogue simulation can be designed and implemented by the teacher allowing for easy adaptation to the particulars of the learners and the school. In this way a contextual and personalized...... learning design is available that provides for interactive and embodied learning, which appeals to the segment of boys that are often difficult to motivate with ordinary uni-modal teaching methods. The paper will present preliminary results from an action research project carried out in collaboration...

  8. Steered molecular dynamics simulations of protein-ligand interactions

    Institute of Scientific and Technical Information of China (English)

    XU; Yechun; SHEN; Jianhua; LUO; Xiaomin; SHEN; Xu; CHEN; Ka

    2004-01-01

    Studies of protein-ligand interactions are helpful to elucidating the mechanisms of ligands, providing clues for rational drug design. The currently developed steered molecular dynamics (SMD) is a complementary approach to experimental techniques in investigating the biochemical processes occurring at microsecond or second time scale, thus SMD may provide dynamical and kinetic processes of ligand-receptor binding and unbinding, which cannot be accessed by the experimental methods. In this article, the methodology of SMD is described, and the applications of SMD simulations for obtaining dynamic insights into protein-ligand interactions are illustrated through two of our own examples. One is associated with the simulations of binding and unbinding processes between huperzine A and acetylcholinesterase, and the other is concerned with the unbinding process of α-APA from HIV-1 reverse transcriptase.

  9. A treecode to simulate dust-plasma interactions

    CERN Document Server

    Thomas, D M

    2016-01-01

    The complex interaction of a small object with its surrounding plasma is an area of significant research with applications in a multitude of astrophysical, atmospheric, industrial and fusion plasmas. The computational study of these interactions has been dominated by macroscopic particle-in-cell (PIC) codes. This paper introduces a microscopic simulator of a spherical dust grain in a plasma, the plasma octree code pot, which uses the Barnes-Hut treecode algorithm to perform $N$-body simulations of electrons and ions in the vicinity of a spherical object. It also employs the Boris particle-motion integrator and Hutchinson's reinjection algorithm from SCEPTIC; a description of all three algorithms, and their implementation, is provided. Test results confirm the successful implementation of the treecode method and question the assumptions made by hybrid PIC codes.

  10. Molecular dynamics simulations of fluid cyclopropane with MP2/CBS-fitted intermolecular interaction potentials.

    Science.gov (United States)

    Ho, Yen-Ching; Wang, Yi-Siang; Chao, Sheng D

    2017-08-14

    Modeling fluid cycloalkanes with molecular dynamics simulations has proven to be a very challenging task partly because of lacking a reliable force field based on quantum chemistry calculations. In this paper, we construct an ab initio force field for fluid cyclopropane using the second-order Møller-Plesset perturbation theory. We consider 15 conformers of the cyclopropane dimer for the orientation sampling. Single-point energies at important geometries are calibrated by the coupled cluster with single, double, and perturbative triple excitation method. Dunning's correlation consistent basis sets (up to aug-cc-pVTZ) are used in extrapolating the interaction energies at the complete basis set limit. The force field parameters in a 9-site Lennard-Jones model are regressed by the calculated interaction energies without using empirical data. With this ab initio force field, we perform molecular dynamics simulations of fluid cyclopropane and calculate both the structural and dynamical properties. We compare the simulation results with those using an empirical force field and obtain a quantitative agreement for the detailed atom-wise radial distribution functions. The experimentally observed gross radial distribution function (extracted from the neutron scattering measurements) is well reproduced in our simulation. Moreover, the calculated self-diffusion coefficients and shear viscosities are in good agreement with the experimental data over a wide range of thermodynamic conditions. To the best of our knowledge, this is the first ab initio force field which is capable of competing with empirical force fields for simulating fluid cyclopropane.

  11. Molecular dynamics simulations of fluid cyclopropane with MP2/CBS-fitted intermolecular interaction potentials

    Science.gov (United States)

    Ho, Yen-Ching; Wang, Yi-Siang; Chao, Sheng D.

    2017-08-01

    Modeling fluid cycloalkanes with molecular dynamics simulations has proven to be a very challenging task partly because of lacking a reliable force field based on quantum chemistry calculations. In this paper, we construct an ab initio force field for fluid cyclopropane using the second-order Møller-Plesset perturbation theory. We consider 15 conformers of the cyclopropane dimer for the orientation sampling. Single-point energies at important geometries are calibrated by the coupled cluster with single, double, and perturbative triple excitation method. Dunning's correlation consistent basis sets (up to aug-cc-pVTZ) are used in extrapolating the interaction energies at the complete basis set limit. The force field parameters in a 9-site Lennard-Jones model are regressed by the calculated interaction energies without using empirical data. With this ab initio force field, we perform molecular dynamics simulations of fluid cyclopropane and calculate both the structural and dynamical properties. We compare the simulation results with those using an empirical force field and obtain a quantitative agreement for the detailed atom-wise radial distribution functions. The experimentally observed gross radial distribution function (extracted from the neutron scattering measurements) is well reproduced in our simulation. Moreover, the calculated self-diffusion coefficients and shear viscosities are in good agreement with the experimental data over a wide range of thermodynamic conditions. To the best of our knowledge, this is the first ab initio force field which is capable of competing with empirical force fields for simulating fluid cyclopropane.

  12. Simulation of hypersonic shock wave - laminar boundary layer interactions

    Science.gov (United States)

    Kianvashrad, N.; Knight, D.

    2017-06-01

    The capability of the Navier-Stokes equations with a perfect gas model for simulation of hypersonic shock wave - laminar boundary layer interactions is assessed. The configuration is a hollow cylinder flare. The experimental data were obtained by Calspan-University of Buffalo (CUBRC) for total enthalpies ranging from 5.07 to 21.85 MJ/kg. Comparison of the computed and experimental surface pressure and heat transfer is performed and the computed §ow¦eld structure is analyzed.

  13. Interactive Exploration of Cosmological Dark-Matter Simulation Data.

    Science.gov (United States)

    Scherzinger, Aaron; Brix, Tobias; Drees, Dominik; Volker, Andreas; Radkov, Kiril; Santalidis, Niko; Fieguth, Alexander; Hinrichs, Klaus H

    2017-01-01

    The winning entry of the 2015 IEEE Scientific Visualization Contest, this article describes a visualization tool for cosmological data resulting from dark-matter simulations. The proposed system helps users explore all aspects of the data at once and receive more detailed information about structures of interest at any time. Moreover, novel methods for visualizing and interactively exploring dark-matter halo substructures are proposed.

  14. ARCHITECTURAL LARGE CONSTRUCTED ENVIRONMENT. MODELING AND INTERACTION USING DYNAMIC SIMULATIONS

    Directory of Open Access Journals (Sweden)

    P. Fiamma

    2012-09-01

    Full Text Available How to use for the architectural design, the simulation coming from a large size data model? The topic is related to the phase coming usually after the acquisition of the data, during the construction of the model and especially after, when designers must have an interaction with the simulation, in order to develop and verify their idea. In the case of study, the concept of interaction includes the concept of real time "flows". The work develops contents and results that can be part of the large debate about the current connection between "architecture" and "movement". The focus of the work, is to realize a collaborative and participative virtual environment on which different specialist actors, client and final users can share knowledge, targets and constraints to better gain the aimed result. The goal is to have used a dynamic micro simulation digital resource that allows all the actors to explore the model in powerful and realistic way and to have a new type of interaction in a complex architectural scenario. On the one hand, the work represents a base of knowledge that can be implemented more and more; on the other hand the work represents a dealt to understand the large constructed architecture simulation as a way of life, a way of being in time and space. The architectural design before, and the architectural fact after, both happen in a sort of "Spatial Analysis System". The way is open to offer to this "system", knowledge and theories, that can support architectural design work for every application and scale. We think that the presented work represents a dealt to understand the large constructed architecture simulation as a way of life, a way of being in time and space. Architecture like a spatial configuration, that can be reconfigurable too through designing.

  15. Neurosurgical simulation by interactive computer graphics on iPad.

    Science.gov (United States)

    Maruyama, Keisuke; Kin, Taichi; Saito, Toki; Suematsu, Shinya; Gomyo, Miho; Noguchi, Akio; Nagane, Motoo; Shiokawa, Yoshiaki

    2014-11-01

    Presurgical simulation before complicated neurosurgery is a state-of-the-art technique, and its usefulness has recently become well known. However, simulation requires complex image processing, which hinders its widespread application. We explored handling the results of interactive computer graphics on the iPad tablet, which can easily be controlled anywhere. Data from preneurosurgical simulations from 12 patients (4 men, 8 women) who underwent complex brain surgery were loaded onto an iPad. First, DICOM data were loaded using Amira visualization software to create interactive computer graphics, and ParaView, another free visualization software package, was used to convert the results of the simulation to be loaded using the free iPad software KiwiViewer. The interactive computer graphics created prior to neurosurgery were successfully displayed and smoothly controlled on the iPad in all patients. The number of elements ranged from 3 to 13 (mean 7). The mean original data size was 233 MB, which was reduced to 10.4 MB (4.4% of original size) after image processing by ParaView. This was increased to 46.6 MB (19.9%) after decompression in KiwiViewer. Controlling the magnification, transfer, rotation, and selection of translucence in 10 levels of each element were smoothly and easily performed using one or two fingers. The requisite skill to smoothly control the iPad software was acquired within 1.8 trials on average in 12 medical students and 6 neurosurgical residents. Using an iPad to handle the result of preneurosurgical simulation was extremely useful because it could easily be handled anywhere.

  16. Stochastic annealing simulations of defect interactions among subcascades

    Energy Technology Data Exchange (ETDEWEB)

    Heinisch, H.L. [Pacific Northwest National Lab., Richland, WA (United States); Singh, B.N.

    1997-04-01

    The effects of the subcascade structure of high energy cascades on the temperature dependencies of annihilation, clustering and free defect production are investigated. The subcascade structure is simulated by closely spaced groups of lower energy MD cascades. The simulation results illustrate the strong influence of the defect configuration existing in the primary damage state on subsequent intracascade evolution. Other significant factors affecting the evolution of the defect distribution are the large differences in mobility and stability of vacancy and interstitial defects and the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. Annealing simulations are also performed on high-energy, subcascade-producing cascades generated with the binary collision approximation and calibrated to MD results.

  17. Investigations and advanced concepts on gyrotron interaction modeling and simulations

    Science.gov (United States)

    Avramidis, K. A.

    2015-12-01

    In gyrotron theory, the interaction between the electron beam and the high frequency electromagnetic field is commonly modeled using the slow variables approach. The slow variables are quantities that vary slowly in time in comparison to the electron cyclotron frequency. They represent the electron momentum and the high frequency field of the resonant TE modes in the gyrotron cavity. For their definition, some reference frequencies need to be introduced. These include the so-called averaging frequency, used to define the slow variable corresponding to the electron momentum, and the carrier frequencies, used to define the slow variables corresponding to the field envelopes of the modes. From the mathematical point of view, the choice of the reference frequencies is, to some extent, arbitrary. However, from the numerical point of view, there are arguments that point toward specific choices, in the sense that these choices are advantageous in terms of simulation speed and accuracy. In this paper, the typical monochromatic gyrotron operation is considered, and the numerical integration of the interaction equations is performed by the trajectory approach, since it is the fastest, and therefore it is the one that is most commonly used. The influence of the choice of the reference frequencies on the interaction simulations is studied using theoretical arguments, as well as numerical simulations. From these investigations, appropriate choices for the values of the reference frequencies are identified. In addition, novel, advanced concepts for the definitions of these frequencies are addressed, and their benefits are demonstrated numerically.

  18. EWS based visual and interactive simulator for plant engineering

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuka, Shiroh [Toshiba Corp. (Japan). Isogo Nuclear Engineering Center; Tanaka, Kazuma; Yoshikawa, Eiji [Toshiba Corp. (Japan). Nuclear Engineering Lab.

    1994-12-31

    The `Plant Engineering Visual and Interactive Simulator (PLEVIS)` is a realtime plant engineering simulator and runs on a general-purpose desk-top engineering workstation with a high-resolution bit-mapped display. PLEVIS is unique in that simulation models are integrated with a control/interlock model editor. PLEVIS can be used in a wide variety of applications, some of which are: (1) Design and modification studies of a control and interlock system, (2) Plant response evaluation for plant start-up testing and troubleshooting, (3) Transient recognition and mitigation studies, and (4) Familiarization with the plant process and control/ interlock system concept. The basic features of PLEVIS in order to realize the above applications are described in the presentation. (1 ref., 6 figs.).

  19. A treecode to simulate dust-plasma interactions

    Science.gov (United States)

    Thomas, D. M.; Holgate, J. T.

    2017-02-01

    The interaction of a small object with surrounding plasma is an area of plasma-physics research with a multitude of applications. This paper introduces the plasma octree code pot, a microscopic simulator of a spheroidal dust grain in a plasma. pot uses the Barnes-Hut treecode algorithm to perform N-body simulations of electrons and ions in the vicinity of a chargeable spheroid, employing also the Boris particle-motion integrator and Hutchinson’s reinjection algorithm from SCEPTIC; a description of the implementation of all three algorithms is provided. We present results from pot simulations of the charging of spheres in magnetised plasmas, and of spheroids in unmagnetized plasmas. The results call into question the validity of using the Boltzmann relation in hybrid PIC codes. Substantial portions of this paper are adapted from chapters 4 and 5 of the first author’s recent PhD dissertation.

  20. Energy distribution of secondary particles in ion beam deposition process of Ag: experiment, calculation and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bundesmann, C.; Feder, R.; Lautenschlaeger, T.; Neumann, H. [Leibniz-Institute of Surface Modification, Leipzig (Germany)

    2015-12-15

    Ion beam sputter deposition allows tailoring the properties of the film-forming, secondary particles (sputtered target particles and backscattered primary particles) and, hence, thin film properties by changing ion beam (ion energy, ion species) and geometrical parameters (ion incidence angle, polar emission angle). In particular, the energy distribution of secondary particles and their influence on the ion beam deposition process of Ag was studied in dependence on process parameters. Energy-selective mass spectrometry was used to measure the energy distribution of sputtered and backscattered ions. The energy distribution of the sputtered particles shows, in accordance with theory, a maximum at low energy and an E{sup -2} decay for energies above the maximum. If the sum of incidence angle and polar emission angle is larger than 90 , additional contributions due to direct sputtering events occur. The energy distribution of the backscattered primary particles can show contributions by scattering at target particles and at implanted primary particles. The occurrence of these contributions depends again strongly on the scattering geometry but also on the primary ion species. The energy of directly sputtered and backscattered particles was calculated using equations based on simple two-particle-interaction whereas the energy distribution was simulated using the well-known Monte Carlo code TRIM.SP. In principal, the calculation and simulation data agree well with the experimental findings. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Two dimensional simulation of high power laser-surface interaction

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, S.R.; Wilke, M.D.; Green, R.E.L.; Johnson, R.P. [Los Alamos National Lab., NM (United States); Busch, G.E. [KMS Fusion, Inc., Ann Arbor, MI (United States)

    1998-08-01

    For laser intensities in the range of 10{sup 8}--10{sup 9} W/cm{sup 2}, and pulse lengths of order 10 {micro}sec or longer, the authors have modified the inertial confinement fusion code Lasnex to simulate gaseous and some dense material aspects of the laser-matter interaction. The unique aspect of their treatment consists of an ablation model which defines a dense material-vapor interface and then calculates the mass flow across this interface. The model treats the dense material as a rigid two-dimensional mass and heat reservoir suppressing all hydrodynamic motion in the dense material. The computer simulations and additional post-processors provide predictions for measurements including impulse given to the target, pressures at the target interface, electron temperatures and densities in the vapor-plasma plume region, and emission of radiation from the target. The authors will present an analysis of some relatively well diagnosed experiments which have been useful in developing their modeling. The simulations match experimentally obtained target impulses, pressures at the target surface inside the laser spot, and radiation emission from the target to within about 20%. Hence their simulational technique appears to form a useful basis for further investigation of laser-surface interaction in this intensity, pulse-width range. This work is useful in many technical areas such as materials processing.

  2. Jovian Plasma Torus Interaction with Europa: 3D Hybrid Kinetic Simulation. First results

    Science.gov (United States)

    Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.; Simpson, D. G.

    2010-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa-moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo orbiter mission, and for planning flyby and orbital measurements, (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy etal.,2007;Shematovichetal.,2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyro radius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions).Non-thermal distributions of upstream plasma will be addressed in future work. Photoionization,electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider two models for background plasma:(a) with O(++) ions; (b) with O(++) and S(++) ions. The majority of O2 atmosphere is thermal with an extended cold population (Cassidyetal.,2007). A few first simulations already include an induced magnetic dipole; however, several important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work.

  3. Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions

    Energy Technology Data Exchange (ETDEWEB)

    Yigit, Cemil; Dzubiella, Joachim, E-mail: joachim.dzubiella@helmholtz-berlin.de [Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin (Germany); Helmholtz Virtual Institute “Multifunctional Biomaterials for Medicine,” 14513 Teltow (Germany); Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin (Germany); Heyda, Jan [Department of Physical Chemistry, University of Chemistry and Technology, Prague, 166 28 Praha 6 (Czech Republic)

    2015-08-14

    We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low salt concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions.

  4. Design, modeling, simulation and evaluation of a distributed energy system

    Science.gov (United States)

    Cultura, Ambrosio B., II

    This dissertation presents the design, modeling, simulation and evaluation of distributed energy resources (DER) consisting of photovoltaics (PV), wind turbines, batteries, a PEM fuel cell and supercapacitors. The distributed energy resources installed at UMass Lowell consist of the following: 2.5kW PV, 44kWhr lead acid batteries and 1500W, 500W & 300W wind turbines, which were installed before year 2000. Recently added to that are the following: 10.56 kW PV array, 2.4 kW wind turbine, 29 kWhr Lead acid batteries, a 1.2 kW PEM fuel cell and 4-140F supercapacitors. Each newly added energy resource has been designed, modeled, simulated and evaluated before its integration into the existing PV/Wind grid-connected system. The Mathematical and Simulink model of each system was derived and validated by comparing the simulated and experimental results. The Simulated results of energy generated from a 10.56kW PV system are in good agreement with the experimental results. A detailed electrical model of a 2.4kW wind turbine system equipped with a permanent magnet generator, diode rectifier, boost converter and inverter is presented. The analysis of the results demonstrates the effectiveness of the constructed simulink model, and can be used to predict the performance of the wind turbine. It was observed that a PEM fuel cell has a very fast response to load changes. Moreover, the model has validated the actual operation of the PEM fuel cell, showing that the simulated results in Matlab Simulink are consistent with the experimental results. The equivalent mathematical equation, derived from an electrical model of the supercapacitor, is used to simulate its voltage response. The model is completely capable of simulating its voltage behavior, and can predict the charge time and discharge time of voltages on the supercapacitor. The bi-directional dc-dc converter was designed in order to connect the 48V battery bank storage to the 24V battery bank storage. This connection was

  5. Examining the interaction of Europa with the Jovian magnetosphere using eruptive and multifluid plasma dynamic simulations

    Science.gov (United States)

    Paty, C. S.; Dufek, J.; Payan, A. P.

    2015-12-01

    Jupiter's icy moon Europa provides a unique laboratory for understanding the physics of moon-magnetosphere interactions. Europa possesses a conductive subsurface ocean, the interaction of which with the locally varying Jovian magnetic field is expressed by the observed inductive response. This icy moon also boasts a dynamic exosphere as well as eruptive plumes, which interact with the Jovian plasma as expressed via ultraviolet aurora. We investigate a broad range of parameter space related to the interaction of this icy moon with the rapidly rotating magnetosphere of Jupiter, systematically working through and quantifying various physical effects using a multifluid plasma dynamic modeling framework. Aside from induction and interactions with the exosphere, we will also present preliminary result from incorporating a neutral plume generated by an eruptive simulation. We run conduit simulations to get at neutral gas and particle injection velocities, which are in turn used as a source for the plasma dynamic simulations. We then investigate the distribution of neutrals, ions, and charged grains as a function of altitude.

  6. Simulation of temperature distribution of point contacts in mixed lubrication

    Institute of Scientific and Technical Information of China (English)

    LIU; Yuchuan(刘雨川); HU; Yuanzhong(胡元中); WANG; Wenzhong; (王文中); WANG; Hui(王慧)

    2002-01-01

    The numerical simulation of temperature distribution of point contacts in mixed lubrication is presented. The calculating includes two steps. First, temperature rises on two surfaces are obtained by a temperature integration method of transient point heat source. Second, the partition coefficients of heat flux are determined by matching the temperature of two surfaces. Similar to the calculation of elastic deformation, double linear interpolation function is used to get a better accuracy, and moving grid method is used to increase the efficiency of the computation. Due to the symmetry of influence coefficient matrix in the direction perpendicular to the velocity, storage and computational work are further reduced by 50%. Numerical samples validate the algorithm and program. The calculating results of the cases of smooth surface and isotropic sinusoidal surface are presented.

  7. Exploratory simulation of an Intelligent Iris Verifier Distributed System

    CERN Document Server

    Popescu-Bodorin, Nicolaie; 10.1109/SACI.2011.5873010

    2011-01-01

    This paper discusses some topics related to the latest trends in the field of evolutionary approaches to iris recognition. It presents the results of an exploratory experimental simulation whose goal was to analyze the possibility of establishing an Interchange Protocol for Digital Identities evolved in different geographic locations interconnected through and into an Intelligent Iris Verifier Distributed System (IIVDS) based on multi-enrollment. Finding a logically consistent model for the Interchange Protocol is the key factor in designing the future large-scale iris biometric networks. Therefore, the logical model of such a protocol is also investigated here. All tests are made on Bath Iris Database and prove that outstanding power of discrimination between the intra- and the inter-class comparisons can be achieved by an IIVDS, even when practicing 52.759.182 inter-class and 10.991.943 intra-class comparisons. Still, the test results confirm that inconsistent enrollment can change the logic of recognition ...

  8. Unbalanced Load Simulation of Electronic Power Transformer in Distribution System

    Institute of Scientific and Technical Information of China (English)

    Wang Dan; Mao Chengxiong; Lu Jiming; Fan Shu; Cao Jiewei; Wang Ben

    2006-01-01

    A control scheme of electronic power transformer (EPT) in a three-phase four-wire distribution system, which included an input section, an isolating section and an output section, was researched under unbalanced loads. The simple and appropriate control scheme was developed through analyzing the system requirements of the primary side and the load requirements of the secondary side. In the input section, a dual-loop control in synchronous rotating d-q coordinates was introduced, and in the output section, a dual-loop control based on instantaneous output voltage wasused. Load characteristics of EPT were investigated by using Matlab/Simulink software. Simulation results showed that, with the proposed control scheme, the EPT has good performances and the sinusoidal input current and constant output voltage can be realized under both balanced and unbalanced loads.

  9. Distribution of electric field for carbon nanotube assembly: Simulation (Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    Soon-Geun KWON; Soo-Hyun KIM; Kwang-Ho KIM; Myung-Chang KANG; Hyung-Woo LEE

    2011-01-01

    The distribution of electric field for the alignment and attachment of carbon nanotubes (CNTs) was simulated. To be attached at the desired place. the aligned and attracted CNTs should be stayed in the desired area called the stable region or the quasi-stable region for an instant where the change of electric field is minimized. Since the conical electrode has the very narrow sized quasi-stable region, few CNTs can be attached. The rectangular electrodes have a wide stable region, so lots of CNTs can be attached. The results indicate that the round electrode which has a proper sized quasi-stable region is more effective for aligning and attaching a single CNT than the conical or rectangular shaped electrodes.

  10. Model simulations of fungal spore distribution over the Indian region

    Science.gov (United States)

    Ansari, Tabish U.; Valsan, Aswathy E.; Ojha, N.; Ravikrishna, R.; Narasimhan, Balaji; Gunthe, Sachin S.

    2015-12-01

    Fungal spores play important role in the health of humans, animals, and plants by constituting a class of the primary biological aerosol particles (PBAPs). Additionally, these could mediate the hydrological cycle by acting as nuclei for ice and cloud formation (IN and CCN respectively). Various processes in the biosphere and the variations in the meteorological conditions control the releasing mechanism of spores through active wet and dry discharge. In the present paper, we simulate the concentration of fungal spores over the Indian region during three distinct meteorological seasons by combining a numerical model (WRF-Chem) with the fungal spore emissions based on land-use type. Maiden high-resolution regional simulations revealed large spatial gradient and strong seasonal dependence in the concentration of fungal spores over the Indian region. The fungal spore concentrations are found to be the highest during winter (0-70 μg m-3 in December), moderately higher during summer (0-35 μg m-3 in May) and lowest during the monsoon (0-25 μg m-3 in July). The elevated concentrations during winter are attributed to the shallower boundary layer trapping the emitted fungal spores in smaller volume. In contrast, the deeper boundary layer mixing in May and stronger monsoonal-convection in July distribute the fungal spores throughout the lower troposphere (∼5 km). We suggest that the higher fungal spore concentrations during winter could have potential health impacts. While, stronger vertical mixing could enable fungal spores to influence the cloud formation during summer and monsoon. Our study provides the first information about the distribution and seasonal variation of fungal spores over the densely populated and observationally sparse Indian region.

  11. Large-scale mass distribution in the Illustris simulation

    Science.gov (United States)

    Haider, M.; Steinhauser, D.; Vogelsberger, M.; Genel, S.; Springel, V.; Torrey, P.; Hernquist, L.

    2016-04-01

    Observations at low redshifts thus far fail to account for all of the baryons expected in the Universe according to cosmological constraints. A large fraction of the baryons presumably resides in a thin and warm-hot medium between the galaxies, where they are difficult to observe due to their low densities and high temperatures. Cosmological simulations of structure formation can be used to verify this picture and provide quantitative predictions for the distribution of mass in different large-scale structure components. Here we study the distribution of baryons and dark matter at different epochs using data from the Illustris simulation. We identify regions of different dark matter density with the primary constituents of large-scale structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift zero, we find that 49 per cent of the dark matter and 23 per cent of the baryons are within haloes more massive than the resolution limit of 2 × 108 M⊙. The filaments of the cosmic web host a further 45 per cent of the dark matter and 46 per cent of the baryons. The remaining 31 per cent of the baryons reside in voids. The majority of these baryons have been transported there through active galactic nuclei feedback. We note that the feedback model of Illustris is too strong for heavy haloes, therefore it is likely that we are overestimating this amount. Categorizing the baryons according to their density and temperature, we find that 17.8 per cent of them are in a condensed state, 21.6 per cent are present as cold, diffuse gas, and 53.9 per cent are found in the state of a warm-hot intergalactic medium.

  12. An Interactive Learning Tutorial on Quantum Key Distribution

    CERN Document Server

    DeVore, Seth

    2016-01-01

    We describe the development and evaluation of a Quantum Interactive Learning Tutorial (QuILT) on quantum key distribution, a context which involves an exciting application of quantum mechanics. The protocol used in the QuILT described here uses single photons with non-orthogonal polarization states to generate a random shared key over a public channel for encrypting and decrypting information. The QuILT helps upper-level undergraduate students learn quantum mechanics using a simple two state system. It actively engages students in the learning process and helps them build links between the formalism and the conceptual aspects of quantum physics without compromising the technical content. The evaluations suggest that the QuILT is helpful in improving students' understanding of relevant concepts.

  13. Development of an interactive tutorial on quantum key distribution

    CERN Document Server

    DeVore, Seth

    2016-01-01

    We describe the development of a Quantum Interactive Learning Tutorial (QuILT) on quantum key distribution, a context which involves a practical application of quantum mechanics. The QuILT helps upper-level undergraduate students learn quantum mechanics using a simple two state system and was developed based upon the findings of cognitive research and physics education research. One protocol used in the QuILT involves generating a random shared key over a public channel for encrypting and decrypting information using single photons with non-orthogonal polarization states, and another protocol makes use of two entangled spin-1/2 particles. The QuILT uses a guided approach and focuses on helping students build links between the formalism and conceptual aspects of quantum physics without compromising the technical content. We also discuss findings from a preliminary in-class evaluation.

  14. UAV based distributed ATR under realistic simulated environmental effects

    Science.gov (United States)

    Chen, Xiaohan; Gong, Shanshan; Schmid, Natalia A.; Valenti, Matthew C.

    2007-04-01

    Over the past several years, the military has grown increasingly reliant upon the use of unattended aerial vehicles (UAVs) for surveillance missions. There is an increasing trend towards fielding swarms of UAVs operating as large-scale sensor networks in the air. Such systems tend to be used primarily for the purpose of acquiring sensory data with the goal of automatic detection, identification, and tracking objects of interest. These trends have been paralleled by advances in both distributed detection, image/signal processing and data fusion techniques. Furthermore, swarmed UAV systems must operate under severe constraints on environmental conditions and sensor limitations. In this work, we investigate the effects of environmental conditions on target detection and recognition performance in a UAV network. We assume that each UAV is equipped with an optical camera, and use a realistic computer simulation to generate synthetic images. The detection algorithm relies on Haar-based features while the automatic target recognition (ATR) algorithm relies on Bessel K features. The performance of both algorithms is evaluated using simulated images that closely mimic data acquired in a UAV network under realistic environmental conditions. We design several fusion techniques and analyze both the case of a single observation and the case of multiple observations of the same target.

  15. Advancing the boundaries of high-connectivity network simulation with distributed computing.

    Science.gov (United States)

    Morrison, Abigail; Mehring, Carsten; Geisel, Theo; Aertsen, A D; Diesmann, Markus

    2005-08-01

    The availability of efficient and reliable simulation tools is one of the mission-critical technologies in the fast-moving field of computational neuroscience. Research indicates that higher brain functions emerge from large and complex cortical networks and their interactions. The large number of elements (neurons) combined with the high connectivity (synapses) of the biological network and the specific type of interactions impose severe constraints on the explorable system size that previously have been hard to overcome. Here we present a collection of new techniques combined to a coherent simulation tool removing the fundamental obstacle in the computational study of biological neural networks: the enormous number of synaptic contacts per neuron. Distributing an individual simulation over multiple computers enables the investigation of networks orders of magnitude larger than previously possible. The software scales excellently on a wide range of tested hardware, so it can be used in an interactive and iterative fashion for the development of ideas, and results can be produced quickly even for very large networks. In contrast to earlier approaches, a wide class of neuron models and synaptic dynamics can be represented.

  16. Interaction of counterions with subtilisin in acetonitrile: insights from molecular dynamics simulations.

    Science.gov (United States)

    Lousa, Diana; Cianci, Michele; Helliwell, John R; Halling, Peter J; Baptista, António M; Soares, Cláudio M

    2012-05-24

    A recent X-ray structure has enabled the location of chloride and cesium ions on the surface of subtilisin Carlsberg in acetonitrile soaked crystals. (1) To complement the previous study and analyze the system in solution, molecular dynamics (MD) simulations, in acetonitrile, were performed using this structure. Additionally, Cl(-) and Cs(+) ions were docked on the protein surface and this system was also simulated. Our results indicate that chloride ions tend to stay close to the protein, whereas cesium ions frequently migrate to the solvent. The distribution of the ions around the enzyme surface is not strongly biased by their initial locations. Replacing cesium by sodium ions showed that the distribution of the two cations is similar, indicating that Cs(+) can be used to find the binding sites of cations like Na(+) and K(+), which, unlike Cs(+), have physiological and biotechnological roles. The Na(+)Cl(-) is more stable than the Cs(+)Cl(-) ion pair, decreasing the probability of interaction between Cl(-) and subtilisin. The comparison of water and acetonitrile simulations indicates that the solvent influences the distribution of the ions. This work provides an extensive theoretical analysis of the interaction between ions and the model enzyme subtilisin in a nonaqueous medium.

  17. Simulation of Au particle interaction on graphene sheets

    Science.gov (United States)

    Mcleod, A.; Vernon, K. C.; Rider, A. E.; Ostrikov, K.

    2013-09-01

    The interaction of Au particles with few layer graphene is of interest for the formation of the next generation of sensing devices 1. In this paper we investigate the coupling of single gold nanoparticles to a graphene sheet, and multiple gold nanoparticles with a graphene sheet using COMSOL Multiphysics. By using these simulations we are able to determine the electric field strength and associated hot-spots for various gold nanoparticle-graphene systems. The Au nanoparticles were modelled as 8 nm diameter spheres on 1.5 nm thick (5 layers) graphene, with properties of graphene obtained from the refractive index data of Weber 2 and the Au refractive index data from Palik 3. The field was incident along the plane of the sheet with polarisation tested for both s and p. The study showed strong localised interaction between the Au and graphene with limited spread; however the double particle case where the graphene sheet separated two Au nanoparticles showed distinct interaction between the particles and graphene. An offset was introduced (up to 4 nm) resulting in much reduced coupling between the opposed particles as the distance apart increased. Findings currently suggest that the graphene layer has limited interaction with incident fields with a single particle present whilst reducing the coupling region to a very fine area when opposing particles are involved. It is hoped that the results of this research will provide insight into graphene-plasmon interactions and spur the development of the next generation of sensing devices.

  18. Modeling interstellar pickup ion distributions in corotating interaction regions inside 1 AU

    Science.gov (United States)

    Chen, J. H.; Schwadron, N. A.; Möbius, E.; Gorby, M.

    2015-11-01

    We present a modeling study of interstellar pickup ion (PUI) distributions in corotating interaction regions (CIRs). We consider gradual compressions associated with CIRs formed when fast speed streams overtake slower streams in the inner heliosphere. For the analysis, we adopt a simplified magnetohydrodynamic model of a CIR. The Energetic Particle Radiation Environment Module, a parallelized particle numerical kinetic code, is used to model PUI distributions using the focused transport equation, including adiabatic cooling/heating, adiabatic focusing, and parallel and perpendicular diffusion. The continuous injection of PUIs is handled as a source term with a ring distribution in velocity space that is produced from the local neutral density obtained from a hot model of the interstellar neutral gas. The simulated distributions exhibit a harder spectrum in the compression region and a softer spectrum in the rarefaction region than that in undisturbed solar wind. As an additional result, a v-5 power law tail distribution above the PUI cutoff speed (a knee in the distribution) emerges for a particular velocity gradient in the CIR. The tail above the PUI cutoff is sensitive to the CIR velocity gradient, and in one observational case studied, this relationship adequately explains the observed spectrum from 2 to 4 times the solar wind speed. This suggests that the velocity gradient associated with the CIR formation can efficiently create a seed population of PUIs before a shock forms even without stochastic acceleration. Thus, local CIR compressions without shocks may play a significant role in the acceleration process as suggested previously.

  19. Simulations of Shock Wave Interaction with a Particle Cloud

    Science.gov (United States)

    Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S.'Bala'

    2016-11-01

    Simulations of a shock wave interacting with a cloud of particles are performed in an attempt to understand similar phenomena observed in dispersal of solid particles under such extreme environment as an explosion. We conduct numerical experiments in which a particle curtain fills only 87% of the shock tube from bottom to top. As such, the particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In this study, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. In these simulations we use a Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. Measurements of particle dispersion are made at different initial volume fractions of the particle cloud. A detailed analysis of the evolution of the particle curtain with respect to the initial conditions is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

  20. Simulating and stimulating performance: Introducing distributed simulation to enhance musical learning and performance

    Directory of Open Access Journals (Sweden)

    Aaron eWilliamon

    2014-02-01

    Full Text Available Musicians typically rehearse far away from their audiences and in practice rooms that differ significantly from the concert venues in which they aspire to perform. Due to the high costs and inaccessibility of such venues, much current international music training lacks repeated exposure to realistic performance situations, with students learning all too late (or not at all how to manage performance stress and the demands of their audiences. Virtual environments have been shown to be an effective training tool in the fields of medicine and sport, offering practitioners access to real-life performance scenarios but with lower risk of negative evaluation and outcomes. The aim of this research was to design and test the efficacy of simulated performance environments in which conditions of real performance could be recreated. Advanced violin students (n=11 were recruited to perform in two simulations: a solo recital with a small virtual audience and an audition situation with three expert virtual judges. Each simulation contained back-stage and on-stage areas, life-sized interactive virtual observers, and pre- and post-performance protocols designed to match those found at leading international performance venues. Participants completed a questionnaire on their experiences of using the simulations. Results show that both simulated environments offered realistic experience of performance contexts and were rated particularly useful for developing performance skills. For a subset of 7 violinists, state anxiety and electrocardiographic data were collected during the simulated audition and an actual audition with real judges. Results display comparable levels of reported state anxiety and patterns of heart rate variability in both situations, suggesting that responses to the simulated audition closely approximate those of a real audition. The findings are discussed in relation to their implications, both generalizable and individual-specific, for

  1. Simulating and stimulating performance: introducing distributed simulation to enhance musical learning and performance

    Science.gov (United States)

    Williamon, Aaron; Aufegger, Lisa; Eiholzer, Hubert

    2014-01-01

    Musicians typically rehearse far away from their audiences and in practice rooms that differ significantly from the concert venues in which they aspire to perform. Due to the high costs and inaccessibility of such venues, much current international music training lacks repeated exposure to realistic performance situations, with students learning all too late (or not at all) how to manage performance stress and the demands of their audiences. Virtual environments have been shown to be an effective training tool in the fields of medicine and sport, offering practitioners access to real-life performance scenarios but with lower risk of negative evaluation and outcomes. The aim of this research was to design and test the efficacy of simulated performance environments in which conditions of “real” performance could be recreated. Advanced violin students (n = 11) were recruited to perform in two simulations: a solo recital with a small virtual audience and an audition situation with three “expert” virtual judges. Each simulation contained back-stage and on-stage areas, life-sized interactive virtual observers, and pre- and post-performance protocols designed to match those found at leading international performance venues. Participants completed a questionnaire on their experiences of using the simulations. Results show that both simulated environments offered realistic experience of performance contexts and were rated particularly useful for developing performance skills. For a subset of 7 violinists, state anxiety and electrocardiographic data were collected during the simulated audition and an actual audition with real judges. Results display comparable levels of reported state anxiety and patterns of heart rate variability in both situations, suggesting that responses to the simulated audition closely approximate those of a real audition. The findings are discussed in relation to their implications, both generalizable and individual-specific, for performance

  2. Innovative Training Concepts for Use in Distributed Interactive Simulation Environments

    Science.gov (United States)

    1994-08-01

    795 2221 6. AUTmOR(S) Winsch, Beverly J.; Atwood , Nancy K.; Sawyer, ROI Alicia R. (BDM Federal, Inc.); Quinkert, Kathleen (ARI); Heiden, Charles K...Environments Beverly J. Winsch, Nancy K. Atwood , and Alicia R. Sawyer BDM Federal, Inc. Kathleen A. Quinkert U.S. Army Research Institute Charles K. Heiden and...addition to the authors, the BDM Federal, Inc., research staff participating in the effort included Silver Campbell, Margaret Shay, and Timothy Voss

  3. Experimental study on interaction between simulated sandstone and acidic fluid

    Institute of Scientific and Technical Information of China (English)

    Zhang Yongwang; Zeng Jianhu; Yu Bingsong

    2009-01-01

    In order to investigate the controlling mechanism of temperature, fluid and other factors on water-rock interaction in the diagenetic process, we performed a series of simulated experiments on the interaction between two kinds of fluids with different salinity and a composite mineral system (simulated sandstone), which contains albite, K-feldspar and other minerals. The experimental results showed that acidity was the most important factor that affected the dissolution of minerals in the composite mineral system. The lower the pH value, the more easily the minerals dissolved. At the same pH value, the dissolution abilities of different acids for various mineral components were also different. Compared to hydrochloric acid (inorganic acid), oxalic acid (organic acid) was more able to dissolve aluminosilicate minerals. However, the dissolution ability of oxalic acid for carbonate minerals was lower than that of hydrochloric acid. In the process of fluid-rock interaction,dissolution of feldspar was relatively complicated. Increase of temperature would accelerate the dissolution of feldspar. Under acidic conditions, albite had a higher dissolution rate than K-feldspar. K-feldspar could dissolve and convert into montmorillonite and kaolinite, while albite could dissolve and convert into kaolinite both at 40℃ and 80℃. Presence of organic acid, and decrease of pH value and water salinity were all favorable for the dissolution of feldspar, but weakened the ability to form clay minerals.

  4. Fluid Structure Interaction Simulations of Pediatric Ventricular Assist Device Operation

    Science.gov (United States)

    Long, Chris; Marsden, Alison; Bazilevs, Yuri

    2011-11-01

    Pediatric ventricular assist devices (PVADs) are used for mechanical circulatory support in children with failing hearts. They can be used to allow the heart to heal naturally or to extend the life of the patient until transplant. A PVAD has two chambers, blood and air, separated by a flexible membrane. The air chamber is pressurized, which drives the membrane and pumps the blood. The primary risk associated with these devices is stroke or embolism from thrombogenesis. Simulation of these devices is difficult due to a complex coupling of two fluid domains and a thin membrane, requiring fluid-structure interaction modeling. The goal of this work is to accurately simulate the hemodynamics of a PVAD. We perform FSI simulations using an Arbitrary Lagrangian-Eulerian (ALE) finite element framework to account for large motions of the membrane and the fluid domains. The air, blood, and membrane are meshed as distinct subdomains, and a method for non-matched discretizations at the fluid-structure interface is presented. The use of isogeometric analysis to model the membrane mechanics is also discussed, and the results of simulations are presented.

  5. Axisymmetric Simulations of Hot Jupiter-Stellar Wind Hydrodynamic Interaction

    CERN Document Server

    Christie, Duncan; Li, Zhi-Yun

    2016-01-01

    Gas giant exoplanets orbiting at close distances to the parent star are subjected to large radiation and stellar wind fluxes. In this paper, hydrodynamic simulations of the planetary upper atmosphere and its interaction with the stellar wind are carried out to understand the possible flow regimes and how they affect the Lyman-alpha transmission spectrum. Following Tremblin and Chiang, charge exchange reactions are included to explore the role of energetic atoms as compared to thermal particles. In order to understand the role of the tail as compared to the leading edge of the planetary gas, the simulations were carried out under axisymmetry, and photoionization and stellar wind electron impact ionization reactions were included to limit the extent of the neutrals away from the planet. By varying the planetary gas temperature, two regimes are found. At high temperature, a supersonic planetary wind is found, which is turned around by the stellar wind and forms a tail behind the planet. At lower temperatures, th...

  6. A Graphical Interactive Simulation Environment for Production Planning in Bacon Factories

    DEFF Research Database (Denmark)

    Nielsen, Kirsten Mølgaard; Nielsen, Jens Frederik Dalsgaard

    1994-01-01

    The paper describes a graphical interactive simulation tool for production planning in bacon factories........The paper describes a graphical interactive simulation tool for production planning in bacon factories.....

  7. Hydrodynamic simulations of the interaction between giant stars and planets

    Science.gov (United States)

    Staff, Jan E.; De Marco, Orsola; Wood, Peter; Galaviz, Pablo; Passy, Jean-Claude

    2016-05-01

    We present the results of hydrodynamic simulations of the interaction between a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with a zero-age main sequence mass of 3.5 M⊙. Dynamic in-spiral time-scales are of the order of few years and a few decades for the red and asymptotic giant branch stars, respectively. The planets will eventually be destroyed at a separation from the core of the giants smaller than the resolution of our simulations, either through evaporation or tidal disruption. As the planets in-spiral, the giant stars' envelopes are somewhat puffed up. Based on relatively long time-scales and even considering the fact that further in-spiral should take place before the planets are destroyed, we predict that the merger would be difficult to observe, with only a relatively small, slow brightening. Very little mass is unbound in the process. These conclusions may change if the planet's orbit enhances the star's main pulsation modes. Based on the angular momentum transfer, we also suspect that this star-planet interaction may be unable to lead to large-scale outflows via the rotation-mediated dynamo effect of Nordhaus and Blackman. Detectable pollution from the destroyed planets would only result for the lightest, lowest metallicity stars. We furthermore find that in both simulations the planets move through the outer stellar envelopes at Mach-3 to Mach-5, reaching Mach-1 towards the end of the simulations. The gravitational drag force decreases and the in-spiral slows down at the sonic transition, as predicted analytically.

  8. Audio-haptic interaction in simulated walking experiences

    DEFF Research Database (Denmark)

    Serafin, Stefania

    2011-01-01

    and interchangeable use of the haptic and auditory modality in floor interfaces, and for the synergy of perception and action in capturing and guiding human walking. We describe the technology developed in the context of this project, together with some experiments performed to evaluate the role of auditory......In this paper an overview of the work conducted on audio-haptic physically based simulation and evaluation of walking is provided. This work has been performed in the context of the Natural Interactive Walking (NIW) project, whose goal is to investigate possibilities for the integrated...

  9. Numerical simulation of multi-fluid shock-turbulence interaction

    Science.gov (United States)

    Tian, Yifeng; Jaberi, Farhad; Livescu, Daniel; Li, Zhaorui

    2017-01-01

    Accurate numerical simulation of multi-fluid Shock-Turbulence Interaction (STI) is conducted by a hybrid monotonicity preserving-compact finite difference scheme for a detailed study of STI in variable density flows. Theoretical and numerical assessments of data confirm that all turbulence scales as well as the STI are well captured by the computational method. Comparison of multi-fluid and single-fluid data indicates that the turbulent kinetic energy is amplified more and the scalar mixing is enhanced more by the shock in flows involving two different fluids/densities when compared with those observed in single-fluid flows.

  10. Working with simulated forms of interaction in health care education

    DEFF Research Database (Denmark)

    Nordentoft, Helle Merete; Olesen, Lektor Birgitte Ravn

    This paper argues that role-play as a simulated form of interaction - live and performed on video - is a creative method which has the potential to generate and support authentic dialogues in practice. In the paper we draw on experiences from 6 interdisciplinary workshops at a Danish hospital...... aspects of health care practices and 2) to display tensions between participants’ different perspectives on the same situation. We conclude that the dialogical process of raising reflexive awareness of tensions makes role-play a powerful creative method in health care education....

  11. Boundary Slip and Surface Interaction: A Lattice Boltzmann Simulation

    Institute of Scientific and Technical Information of China (English)

    CHEN Yan-Yan; YI Hou-Hui; LI Hua-Bing

    2008-01-01

    The factors affecting slip length in Couette geometry flows are analysed by means of a two-phase mesoscopic lattice Boltzmann model including non-ideal fluid-fluid and fluid-wall interactions.The main factors influencing the boundary slip are the strength of interactions between fluid-fluid and fluid-wall particles.Other factors,such as fluid viscosity,bulk pressure may also change the slip length.We find that boundary slip only occurs under a certain density(bulk pressure).If the density is large enough,the slip length will tend to zero.In our simulations,a low density layer near the wall does not need to be postulated a priori but emerges naturally from the underlying non-ideal mesoscopic dynamics.It is the low density layer that induces the boundary slip.The results may be helpful to understand recent experimental observations on the slippage of micro flows.

  12. Simulation of Interaction of Strong Shocks with Gas Bubbles using the Direct Simulation Monte Carlo Method

    Science.gov (United States)

    Puranik, Bhalchandra; Watvisave, Deepak; Bhandarkar, Upendra

    2016-11-01

    The interaction of a shock with a density interface is observed in several technological applications such as supersonic combustion, inertial confinement fusion, and shock-induced fragmentation of kidney and gall-stones. The central physical process in this interaction is the mechanism of the Richtmyer-Meshkov Instability (RMI). The specific situation where the density interface is initially an isolated spherical or cylindrical gas bubble presents a relatively simple geometry that exhibits all the essential RMI processes such as reflected and refracted shocks, secondary instabilities, turbulence and mixing of the species. If the incident shocks are strong, the calorically imperfect nature needs to be modelled. In the present work, we have carried out simulations of the shock-bubble interaction using the DSMC method for such situations. Specifically, an investigation of the shock-bubble interaction with diatomic gases involving rotational and vibrational excitations at high temperatures is performed, and the effects of such high temperature phenomena will be presented.

  13. SIMULATION OF FLUID-SOLID INTERACTION ON WATER DITCHING OF AN AIRPLANE BY ALE METHOD

    Institute of Scientific and Technical Information of China (English)

    HUA Cheng; FANG Chao; CHENG Jin

    2011-01-01

    Ditching is considered as one of the important aspects of safety performances of airplanes.It is related primarily with the fluid-solid interaction,whose studies mainly depend on experiments at the present time.Numerical and analytical methods for fluid-solid interaction by using 3-D full scale airplane's model will reduce the dependence on the expensive model tests.Numerical studies can be used to estimate the safety of ditching and provide a reference for the crashworthiness design.This article proposes a 3-D dynamical structural model after the real shape of an airplane and an Arbitrary Lagrange-Euler (ALE) fluid-field model,to simulate the fluid-solid interactions caused by low speed ditching.The simulation is based on interaction computational methods,within LS-DYNA nonlinear finite-element code.The results of pressure distributions and accelerating time histories of the airplane's subfloor are discussed in the context of the safety of ditching,and the simulation results and the analytical methods are verified.

  14. Molecular Statics Simulation of Hydrogen Defect Interaction in Tungsten

    Science.gov (United States)

    Li, Xiaochun; Liu, Yinan; Yu, Yi; Niu, Guojian; Luo, Guangnan; Shu, Xiaolin

    2015-06-01

    Hydrogen (H) defect interactions have been investigated by molecular statics simulations in tungsten (W), including H-H interactions and interactions between H and W self-interstitial atoms. The interactions between H and small H-vacancy clusters are also demonstrated; the binding energies of an H, a vacancy and a self-interstitial W to an H-vacancy cluster depend on the H-to-vacancy ratio. We conclude that H bubble formation needs a high concentration of H in W for the H bubble nucleation and growth, which are also governed by the H-to-vacancy ratio of the cluster. The vacancy first combines with H atoms and a cluster forms, then the H-vacancy cluster goes through the whole process of vacancy capture, H capture, and vacancy capture again, and as a result the H-vacancy cluster grows larger and larger. Finally, the H bubble forms. supported by National Natural Science Foundation of China (Nos. 51171008 and 11405201) and the National Magnetic Confinement Fusion Science Program of China (No. 2013GB1090)

  15. Numerical simulations of a shock interacting with multiple magnetized clouds

    Science.gov (United States)

    Alūzas, R.; Pittard, J. M.; Falle, S. A. E. G.; Hartquist, T. W.

    2014-10-01

    We present 2D adiabatic magnetohydrodynamic simulations of a shock interacting with groups of two or three cylindrical clouds. We study how the presence of a nearby cloud influences the dynamics of this interaction, and explore the resulting differences and similarities in the evolution of each cloud. The understanding gained from this small-scale study will help to interpret the behaviour of systems with many 10s or 100s of clouds. We observe a wide variety of behaviour in the interactions studied, which is dependent on the initial positions of the clouds and the orientation and strength of the magnetic field. We find (i) some clouds are stretched along their field lines, whereas others are confined by their field lines; (ii) upstream clouds may accelerate past downstream clouds (though magnetic tension can prevent this); (iii) clouds may also change their relative positions transverse to the direction of shock propagation as they `slingshot' past each other; (iv) downstream clouds may be offered some protection from the oncoming flow as a result of being in the lee of an upstream cloud; (v) the cycle of cloud compression and re-expansion is generally weaker when there are nearby neighbouring clouds; (vi) the plasma β in cloud material can vary rapidly as clouds collide with one another, but low values of β are always transitory. This work is relevant to studies of multiphase regions, where fast, low-density gas interacts with dense clouds, such as in circumstellar bubbles, supernova remnants, superbubbles and galactic winds.

  16. Pigeon interaction mode switch-based UAV distributed flocking control under obstacle environments.

    Science.gov (United States)

    Qiu, Huaxin; Duan, Haibin

    2017-07-28

    Unmanned aerial vehicle (UAV) flocking control is a serious and challenging problem due to local interactions and changing environments. In this paper, a pigeon flocking model and a pigeon coordinated obstacle-avoiding model are proposed based on a behavior that pigeon flocks will switch between hierarchical and egalitarian interaction mode at different flight phases. Owning to the similarity between bird flocks and UAV swarms in essence, a distributed flocking control algorithm based on the proposed pigeon flocking and coordinated obstacle-avoiding models is designed to coordinate a heterogeneous UAV swarm to fly though obstacle environments with few informed individuals. The comparative simulation results are elaborated to show the feasibility, validity and superiority of our proposed algorithm. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  17. On the Relation of Wave-Particle Interactions, Particle Dynamics, and Suprathermal Particle Distributions

    Science.gov (United States)

    Kucharek, Harald; Galvin, Antoinette; Farrugia, Charles; Klecker, Berndt; Pogorelov, Nikolai

    2016-04-01

    Wave-particle interactions, ion acceleration, and magnetic turbulence are closely interlinked and the physical processes may occur on different scales. These scales range from the kinetic scale to the macro-scale (MHD-scale). These processes are likely universal and the same basic processes occur at the Earth's environment, at the Earth's bow shock, the solar wind, and around the heliosphere. Undoubtedly, the Earth's environment as well as the close interplanetary space are the best plasma environments to study these processes using satellite measurements. Recently, ACE, STEREO, IBEX and Voyager observations clearly showed that turbulence and wave-particle interactions and turbulence are extremely important in interplanetary space and in the heliosphere. Using data from STEREO, Wind, we have investigated the spectral properties of suprathermal ion distributions. The results show that spectral slopes are very variable and depend on the plasma properties. We have also performed 3D hybrid simulations and studied particle dynamics. These simulations show that the particle dynamics in the turbulent magnetic wave field is Levy-Flight like which leads to a kappa distribution, which is often found in various space environments. This result is very significant of future mission such as THOR and IMAP and current operating missions such as STEREO, IBEX, and MMS.

  18. Simulation and Experimental Validation of Hypersonic Shock Wave Interaction

    Directory of Open Access Journals (Sweden)

    Li Jing

    2013-12-01

    Full Text Available The present paper examines the relevance of grid and simulation accuracy of hypersonic CFD in terms of hypersonic sharp double-cone flow. The flow grid and normal grid each adopted 250×100, 500×100, 1000×100, 500×200, 1000×200, 1000×400 and so on grids. When the normal grid was 100, the wall pressure and heat flux distribution obtained from flow grid 500 and 1000 were consistent, indicating that the solution of flow grid convergence was obtained. However, some difference was observed when the separation zone was compared with the experimental data. In increasing the normal grid number and adopting grid 500×200, the position of the separation point, wall pressure and heat flux peak was shown to be consistent with the experiment. When the grid was further encrypted, the calculation using grid 1000×200 and 1000×400 was equal to that using grid 500×200. The simulation of hypersonic sharp double-cone flow also showed that when the separation zone of the simulation was less than the experimental measurement, the wall pressure and heat flux peak moved forward. This is because the backwardness of the intersection of the separation shock and the first shock resulted in the forwardness of the intersection of the first shock and the second shock after interference, making the work region of the induction shock and boundary layer move forward. The key challenge in achieving the correct simulation of the hypersonic sharp double-cone flow is explained as follows: the algorithm can not only capture shock wave strength correctly and give the adverse pressure gradient formed by the interfering shock wave near the wall accurately. It can also prevent the numerical dissipation of the algorithm from affecting the simulation accuracy of the viscous boundary layer to ensure the correct prediction of the size of the separation zone.

  19. Lattice Boltzmann simulations of multiple-droplet interaction dynamics

    Science.gov (United States)

    Zhou, Wenchao; Loney, Drew; Fedorov, Andrei G.; Degertekin, F. Levent; Rosen, David W.

    2014-03-01

    A lattice Boltzmann (LB) formulation, which is consistent with the phase-field model for two-phase incompressible fluid, is proposed to model the interface dynamics of droplet impingement. The interparticle force is derived by comparing the macroscopic transport equations recovered from LB equations with the governing equations of the continuous phase-field model. The inconsistency between the existing LB implementations and the phase-field model in calculating the relaxation time at the phase interface is identified and an approximation is proposed to ensure the consistency with the phase-field model. It is also shown that the commonly used equilibrium velocity boundary for the binary fluid LB scheme does not conserve momentum at the wall boundary and a modified scheme is developed to ensure the momentum conservation at the boundary. In addition, a geometric formulation of the wetting boundary condition is proposed to replace the popular surface energy formulation and results show that the geometric approach enforces the prescribed contact angle better than the surface energy formulation in both static and dynamic wetting. The proposed LB formulation is applied to simulating droplet impingement dynamics in three dimensions and results are compared to those obtained with the continuous phase-field model, the LB simulations reported in the literature, and experimental data from the literature. The results show that the proposed LB simulation approach yields not only a significant speed improvement over the phase-field model in simulating droplet impingement dynamics on a submillimeter length scale, but also better accuracy than both the phase-field model and the previously reported LB techniques when compared to experimental data. Upon validation, the proposed LB modeling methodology is applied to the study of multiple-droplet impingement and interactions in three dimensions, which demonstrates its powerful capability of simulating extremely complex interface

  20. An Object-Oriented Interactive System for Scientific Simulations : Design and Applications

    NARCIS (Netherlands)

    Telea, A.C.; Overveld, C.W.A.M. van

    1998-01-01

    Better insight in complex physical processes requires integration of scientific visualization and numerical simulation in a single interactive framework. This paper presents an object-oriented environment which combines the tasks of numerical simulation, visualization, simulation specification, run-

  1. Towards understanding tree root profiles: simulating hydrologically optimal strategies for root distribution

    Directory of Open Access Journals (Sweden)

    M. T. van Wijk

    2001-01-01

    Full Text Available In this modelling study differences in vertical root distributions measured in four contrasting forest locations in the Netherlands were investigated. Root distributions are seen as a reflection of the plant’s optimisation strategy, based on hydrological grounds. The 'optimal' root distribution is defined as the one that maximises the water uptake from the root zone over a period of ten years. The optimal root distributions of four forest locations with completely different soil physical characteristics are calculated using the soil hydrological model SWIF. Two different model configurations for root interactions were tested: the standard model configuration in which one single root profile was used (SWIF-NC, and a model configuration in which two root profiles compete for the same available water (SWIF-C. The root profiles were parameterised with genetic algorithms. The fitness of a certain root profile was defined as the amount of water uptake over a simulation period of ten years. The root profiles of SWIF-C were optimised using an evolutionary game. The results showed clear differences in optimal root distributions between the various sites and also between the two model configurations. Optimisation with SWIF-C resulted in root profiles that were easier to interpret in terms of feasible biological strategies. Preferential water uptake in wetter soil regions was an important factor for interpretation of the simulated root distributions. As the optimised root profiles still showed differences with measured profiles, this analysis is presented, not as the final solution for explaining differences in root profiles of vegetation but as a first step using an optimisation theory to increase understanding of the root profiles of trees. Keywords: forest hydrology, optimisation, roots

  2. Distribution and interaction patterns of bacterial communities in an ornithogenic soil of Seymour Island, Antarctica.

    Science.gov (United States)

    Rampelotto, Pabulo Henrique; Barboza, Anthony Diego Muller; Pereira, Antônio Batista; Triplett, Eric W; Schaefer, Carlos Ernesto G R; de Oliveira Camargo, Flávio Anastácio; Roesch, Luiz Fernando Wurdig

    2015-04-01

    Next-generation, culture-independent sequencing offers an excellent opportunity to examine network interactions among different microbial species. In this study, soil bacterial communities from a penguin rookery site at Seymour Island were analyzed for abundance, structure, diversity, and interaction networks to identify interaction patterns among the various taxa at three soil depths. The analysis revealed the presence of eight phyla distributed in different proportions among the surface layer (0-8 cm), middle layer (20-25 cm), and bottom (35-40 cm). The bottom layer presented the highest values of bacterial richness, diversity, and evenness when compared to surface and middle layers. The network analysis revealed the existence of a unique pattern of interactions in which the soil microbial network formed a clustered topology, rather than a modular structure as is usually found in biological communities. In addition, specific taxa were identified as important players in microbial community structure. Furthermore, simulation analyses indicated that the loss of potential keystone groups of microorganisms might alter the patterns of interactions within the microbial community. These findings provide new insights for assessing the consequences of environmental disturbances at the whole-community level in Antarctica.

  3. AXISYMMETRIC SIMULATIONS OF HOT JUPITER–STELLAR WIND HYDRODYNAMIC INTERACTION

    Energy Technology Data Exchange (ETDEWEB)

    Christie, Duncan; Arras, Phil; Li, Zhi-Yun [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)

    2016-03-20

    Gas giant exoplanets orbiting at close distances to the parent star are subjected to large radiation and stellar wind fluxes. In this paper, hydrodynamic simulations of the planetary upper atmosphere and its interaction with the stellar wind are carried out to understand the possible flow regimes and how they affect the Lyα transmission spectrum. Following Tremblin and Chiang, charge exchange reactions are included to explore the role of energetic atoms as compared to thermal particles. In order to understand the role of the tail as compared to the leading edge of the planetary gas, the simulations were carried out under axisymmetry, and photoionization and stellar wind electron impact ionization reactions were included to limit the extent of the neutrals away from the planet. By varying the planetary gas temperature, two regimes are found. At high temperature, a supersonic planetary wind is found, which is turned around by the stellar wind and forms a tail behind the planet. At lower temperatures, the planetary wind is shut off when the stellar wind penetrates inside where the sonic point would have been. In this regime mass is lost by viscous interaction at the boundary between planetary and stellar wind gases. Absorption by cold hydrogen atoms is large near the planetary surface, and decreases away from the planet as expected. The hot hydrogen absorption is in an annulus and typically dominated by the tail, at large impact parameter, rather than by the thin leading edge of the mixing layer near the substellar point.

  4. Building interactive simulations in a Web page design program.

    Science.gov (United States)

    Kootsey, J Mailen; Siriphongs, Daniel; McAuley, Grant

    2004-01-01

    A new Web software architecture, NumberLinX (NLX), has been integrated into a commercial Web design program to produce a drag-and-drop environment for building interactive simulations. NLX is a library of reusable objects written in Java, including input, output, calculation, and control objects. The NLX objects were added to the palette of available objects in the Web design program to be selected and dropped on a page. Inserting an object in a Web page is accomplished by adding a template block of HTML code to the page file. HTML parameters in the block must be set to user-supplied values, so the HTML code is generated dynamically, based on user entries in a popup form. Implementing the object inspector for each object permits the user to edit object attributes in a form window. Except for model definition, the combination of the NLX architecture and the Web design program permits construction of interactive simulation pages without writing or inspecting code.

  5. Monte Carlo Simulations of Cosmic Rays Hadronic Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Aguayo Navarrete, Estanislao; Orrell, John L.; Kouzes, Richard T.

    2011-04-01

    This document describes the construction and results of the MaCoR software tool, developed to model the hadronic interactions of cosmic rays with different geometries of materials. The ubiquity of cosmic radiation in the environment results in the activation of stable isotopes, referred to as cosmogenic activities. The objective is to use this application in conjunction with a model of the MAJORANA DEMONSTRATOR components, from extraction to deployment, to evaluate cosmogenic activation of such components before and after deployment. The cosmic ray showers include several types of particles with a wide range of energy (MeV to GeV). It is infeasible to compute an exact result with a deterministic algorithm for this problem; Monte Carlo simulations are a more suitable approach to model cosmic ray hadronic interactions. In order to validate the results generated by the application, a test comparing experimental muon flux measurements and those predicted by the application is presented. The experimental and simulated results have a deviation of 3%.

  6. 2D velocity fields of simulated interacting disc galaxies

    CERN Document Server

    Kronberger, T; Schindler, S; Ziegler, B L

    2007-01-01

    We investigate distortions in the velocity fields of disc galaxies and their use to reveal the dynamical state of interacting galaxies at different redshift. For that purpose, we model disc galaxies in combined N-body/hydrodynamic simulations. 2D velocity fields of the gas are extracted from these simulations which we place at different redshifts from z=0 to z=1 to investigate resolution effects on the properties of the velocity field. To quantify the structure of the velocity field we also perform a kinemetry analysis. If the galaxy is undisturbed we find that the rotation curve extracted from the 2D field agrees well with long-slit rotation curves. This is not true for interacting systems, as the kinematic axis is not well defined and does in general not coincide with the photometric axis of the system. For large (Milky way type) galaxies we find that distortions are still visible at intermediate redshifts but partly smeared out. Thus a careful analysis of the velocity field is necessary before using it for...

  7. Interaction of light with hematite hierarchical structures: Experiments and simulations

    Science.gov (United States)

    Distaso, Monica; Zhuromskyy, Oleksander; Seemann, Benjamin; Pflug, Lukas; Mačković, Mirza; Encina, Ezequiel; Taylor, Robin Klupp; Müller, Rolf; Leugering, Günter; Spiecker, Erdmann; Peschel, Ulf; Peukert, Wolfgang

    2017-03-01

    Mesocrystalline particles have been recognized as a class of multifunctional materials with potential applications in different fields. However, the internal organization of nanocomposite mesocrystals and its influence on the final properties have not yet been investigated. In this paper, a novel strategy based on electrodynamic simulations is developed to shed light on how the internal structure of mesocrystals influences their optical properties. In a first instance, a unified design protocol is reported for the fabrication of hematite/PVP particles with different morphologies such as pseudo-cubes, rods-like and apple-like structures and controlled particle size distributions. The optical properties of hematite/PVP mesocrystals are effectively simulated by taking their aggregate and nanocomposite structure into consideration. The superposition T-Matrix approach accounts for the aggregate nature of mesocrystalline particles and validate the effective medium approximation used in the framework of the Mie theory and electromagnetic simulation such as Finite Element Method. The approach described in our paper provides the framework to understand and predict the optical properties of mesocrystals and more general, of hierarchical nanostructured particles.

  8. Virtual patient simulator for distributed collaborative medical education.

    Science.gov (United States)

    Caudell, Thomas P; Summers, Kenneth L; Holten, Jim; Hakamata, Takeshi; Mowafi, Moad; Jacobs, Joshua; Lozanoff, Beth K; Lozanoff, Scott; Wilks, David; Keep, Marcus F; Saiki, Stanley; Alverson, Dale

    2003-01-01

    Project TOUCH (Telehealth Outreach for Unified Community Health; http://hsc.unm.edu/touch) investigates the feasibility of using advanced technologies to enhance education in an innovative problem-based learning format currently being used in medical school curricula, applying specific clinical case models, and deploying to remote sites/workstations. The University of New Mexico's School of Medicine and the John A. Burns School of Medicine at the University of Hawai'i face similar health care challenges in providing and delivering services and training to remote and rural areas. Recognizing that health care needs are local and require local solutions, both states are committed to improving health care delivery to their unique populations by sharing information and experiences through emerging telehealth technologies by using high-performance computing and communications resources. The purpose of this study is to describe the deployment of a problem-based learning case distributed over the National Computational Science Alliance's Access Grid. Emphasis is placed on the underlying technical components of the TOUCH project, including the virtual reality development tool Flatland, the artificial intelligence-based simulation engine, the Access Grid, high-performance computing platforms, and the software that connects them all. In addition, educational and technical challenges for Project TOUCH are identified.

  9. Numerical Simulation of Particle Distribution in Capillary Membrane during Backwash

    Directory of Open Access Journals (Sweden)

    Anik Keller

    2013-09-01

    Full Text Available The membrane filtration with inside-out dead-end driven UF-/MF- capillary membranes is an effective process for particle removal in water treatment. Its industrial application increased in the last decade exponentially. To date, the research activities in this field were aimed first of all at the analysis of filtration phenomena disregarding the influence of backwash on the operation parameters of filtration plants. However, following the main hypothesis of this paper, backwash has great potential to increase the efficiency of filtration. In this paper, a numerical approach for a detailed study of fluid dynamic processes in capillary membranes during backwash is presented. The effect of particle size and inlet flux on the backwash process are investigated. The evaluation of these data concentrates on the analysis of particle behavior in the cross sectional plane and the appearance of eventually formed particle plugs inside the membrane capillary. Simulations are conducted in dead-end filtration mode and with two configurations. The first configuration includes a particle concentration of 10% homogeneously distributed within the capillary and the second configuration demonstrates a cake layer on the membrane surface with a packing density of 0:6. Analyzing the hydrodynamic forces acting on the particles shows that the lift force plays the main role in defining the particle enrichment areas. The operation parameters contribute in enhancing the lift force and the heterogeneity to anticipate the clogging of the membrane.

  10. Numerical Simulations of a Shock Interacting with Multiple Magnetized Clouds

    CERN Document Server

    Alūzas, R; Falle, S A E G; Hartquist, T W

    2014-01-01

    We present 2D adiabatic magnetohydrodynamic (MHD) simulations of a shock interacting with groups of two or three cylindrical clouds. We study how the presence of a nearby cloud influences the dynamics of this interaction, and explore the resulting differences and similarities in the evolution of each cloud. The understanding gained from this small-scale study will help to interpret the behaviour of systems with many 10's or 100's of clouds. We observe a wide variety of behaviour in the interactions studied, which is dependent on the initial positions of the clouds and the orientation and strength of the magnetic field. We find: i) some clouds are stretched along their field-lines, whereas others are confined by their field-lines; ii) upstream clouds may accelerate past downstream clouds (though magnetic tension can prevent this); iii) clouds may also change their relative positions transverse to the direction of shock propagation as they "slingshot" past each other; iv) downstream clouds may be offered some p...

  11. Lattice-Boltzmann Simulations of Microswimmer-Tracer Interactions

    CERN Document Server

    de Graaf, Joost

    2016-01-01

    Hydrodynamic interactions in systems comprised of self-propelled particles, such as swimming microorganisms, and passive tracers have a significant impact on the tracer dynamics compared to the equivalent "dry" sample. However, such interactions are often difficult to take into account in simulations due to their computational cost. Here, we perform a systematic investigation of swimmer-tracer interaction using an efficient force/counter-force based lattice-Boltzmann (LB) algorithm [J. de Graaf~\\textit{et al.}, J. Chem. Phys.~\\textbf{144}, 134106 (2016)], in order to validate its applicability to study large-scale microswimmer suspensions. We show that the LB algorithm reproduces far-field theoretical results well, both in a system with periodic boundary conditions and in a spherical cavity with no-slip walls, for which we derive expressions here. The LB algorithm has an inherent near-field renormalization of the flow field, due to the force interpolation between the swimmers and the lattice. This strongly pe...

  12. Simulations of structure formation in interacting dark energy cosmologies

    CERN Document Server

    Baldi, Marco

    2009-01-01

    The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We review here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models, as already presented in Baldi et al. [20]. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these...

  13. Simulating the interaction of jets with the intracluster medium

    Science.gov (United States)

    Weinberger, Rainer; Ehlert, Kristian; Pfrommer, Christoph; Pakmor, Rüdiger; Springel, Volker

    2017-10-01

    Jets from supermassive black holes in the centres of galaxy clusters are a potential candidate for moderating gas cooling and subsequent star formation through depositing energy in the intracluster gas. In this work, we simulate the jet-intracluster medium interaction using the moving-mesh magnetohydrodynamics code arepo. Our model injects supersonic, low-density, collimated and magnetized outflows in cluster centres, which are then stopped by the surrounding gas, thermalize and inflate low-density cavities filled with cosmic rays. We perform high-resolution, non-radiative simulations of the lobe creation, expansion and disruption, and find that its dynamical evolution is in qualitative agreement with simulations of idealized low-density cavities that are dominated by a large-scale Rayleigh-Taylor instability. The buoyant rising of the lobe does not create energetically significant small-scale chaotic motion in a volume-filling fashion, but rather a systematic upward motion in the wake of the lobe and a corresponding back-flow antiparallel to it. We find that, overall, 50 per cent of the injected energy ends up in material that is not part of the lobe, and about 25 per cent remains in the inner 100 kpc. We conclude that jet-inflated, buoyantly rising cavities drive systematic gas motions that play an important role in heating the central regions, while mixing of lobe material is subdominant. Encouragingly, the main mechanisms responsible for this energy deposition can be modelled already at resolutions within reach in future, high-resolution cosmological simulations of galaxy clusters.

  14. Simulation of Metal Flow During Friction Stir Welding Based on the Model of Interactive Force Between Tool and Material

    Science.gov (United States)

    Chen, G. Q.; Shi, Q. Y.; Fujiya, Y.; Horie, T.

    2014-04-01

    In this research, the three-dimensional flow of metal in friction stir welding (FSW) has been simulated based on computational fluid dynamics. Conservation equations of mass, momentum, and energy were solved in three dimensions. The interactive force was imposed as boundary conditions on the tool/material boundary in the model. The strain rate- and temperature-dependent non-Newtonian viscosity was adopted for the calculation of metal flow. The distribution of temperature, velocity, and strain rate were simulated based on the above models. The simulated temperature distribution agreed well with the experimental results. The simulation results showed that the velocity on the pin was much higher than that on the shoulder. From the comparison between the simulation results and the experiments results, contours line, corresponding to strain rate = 4 s-1, reflected reasonably well the shape of stir zone, especially at the ground portion.

  15. Two-way coupled fluid structure interaction simulation of a propeller turbine

    Energy Technology Data Exchange (ETDEWEB)

    Schmucker, H [Voith Hydro GmbH and Co. KG, Germany Alexanderstrasse 11, 89522 Heidenheim (Germany); Flemming, F; Coulson, S, E-mail: Hannes.Schmucker@voith.co [Voith Hydro Inc. York, PA, 760 East Berlin Road, York, PA, 17408 (United States)

    2010-08-15

    During the operation of a hydro turbine the fluid mechanical pressure loading on the turbine blades provides the driving torque on the turbine shaft. This fluid loading results in a structural load on the component which in turn causes the turbine blade to deflect. Classically, these mechanical stresses and deflections are calculated by means of finite element analysis (FEA) which applies the pressure distribution on the blade surface calculated by computational fluid dynamics (CFD) as a major boundary condition. Such an approach can be seen as a oneway coupled simulation of the fluid structure interaction (FSI) problem. In this analysis the reverse influence of the deformation on the fluid is generally neglected. Especially in axial machines the blade deformation can result in a significant impact on the turbine performance. The present paper analyzes this influence by means of fully two-way coupled FSI simulations of a propeller turbine utilizing two different approaches. The configuration has been simulated by coupling the two commercial solvers ANSYS CFX for the fluid mechanical simulation with ANSYS Classic for the structure mechanical simulation. A detailed comparison of the results for various blade stiffness by means of changing Young's Modulus are presented. The influence of the blade deformation on the runner discharge and performance will be discussed and shows for the configuration investigated no significant influence under normal structural conditions. This study also highlights that a two-way coupled fluid structure interaction simulation of a real engineering configuration is still a challenging task for today's commercially available simulation tools.

  16. Hydroacoustic simulation of rotor-stator interaction in resonance conditions in Francis pump-turbine

    Energy Technology Data Exchange (ETDEWEB)

    Nicolet, C [Power Vision Engineering sarl, Ch. des Champs-Courbes 1, CH-1024 Ecublens (Switzerland); Ruchonnet, N; Alligne, S; Avellan, F [EPFL Laboratory for Hydraulic Machines, Av. de Cour 33bis, CH-1007 Lausanne (Switzerland); Koutnik, J, E-mail: christophe.nicolet@powervision-eng.c [Voith Hydro Holding GmbH and Co. KG, Alexanderstr. 11, 89522 Heidenheim (Germany)

    2010-08-15

    Combined effect of rotating pressure field related to runner blade and wakes of wicket gates leads to rotor stator interactions, RSI, in Francis pump-turbines. These interactions induce pressures waves propagating in the entire hydraulic machine. Superposition of those pressure waves may result in standing wave in the spiral casing and rotating diametrical mode in the guide vanes and can cause strong pressure fluctuations and vibrations. This paper presents the modeling, simulation and analysis of Rotor-Stator Interaction of a scale model of a Francis pump-turbine and related test rig using a one-dimensional approach. The hydroacoustic modeling of the Francis pump-turbine takes into account the spiral casing, the 20 guide vanes, the 9 rotating runner vanes. The connection between stationary and rotating parts is ensured by a valve network driven according to the unsteady flow distribution between guide vanes and runner vanes. Time domain simulations are performed for 2 different runner rotational speeds in turbine mode. The simulation results are analyzed in frequency domain and highlights hydroacoustic resonance between RSI excitations and the spiral case. Rotating diametrical mode in the vaneless gap and standing wave in the spiral case are identified. The influence of the resonance on phase and amplitude of pressure fluctuations obtained for both the spiral case and the vaneless gap is analyzed. The mode shape and frequencies are confirmed using eigenvalues analysis.

  17. Migrating to a real-time distributed parallel simulator architecture- An update

    CSIR Research Space (South Africa)

    Duvenhage, B

    2007-09-01

    Full Text Available A legacy non-distributed logical time simulator was previously migrated to a distributed architecture to parallelise execution. The existing Discrete Time System Specification (DTSS) modelling formalism was retained to simplify the reuse of existing...

  18. Web-based Interactive Landform Simulation Model - Grand Canyon

    Science.gov (United States)

    Luo, W.; Pelletier, J. D.; Duffin, K.; Ormand, C. J.; Hung, W.; Iverson, E. A.; Shernoff, D.; Zhai, X.; Chowdary, A.

    2013-12-01

    Earth science educators need interactive tools to engage and enable students to better understand how Earth systems work over geologic time scales. The evolution of landforms is ripe for interactive, inquiry-based learning exercises because landforms exist all around us. The Web-based Interactive Landform Simulation Model - Grand Canyon (WILSIM-GC, http://serc.carleton.edu/landform/) is a continuation and upgrade of the simple cellular automata (CA) rule-based model (WILSIM-CA, http://www.niu.edu/landform/) that can be accessed from anywhere with an Internet connection. Major improvements in WILSIM-GC include adopting a physically based model and the latest Java technology. The physically based model is incorporated to illustrate the fluvial processes involved in land-sculpting pertaining to the development and evolution of one of the most famous landforms on Earth: the Grand Canyon. It is hoped that this focus on a famous and specific landscape will attract greater student interest and provide opportunities for students to learn not only how different processes interact to form the landform we observe today, but also how models and data are used together to enhance our understanding of the processes involved. The latest development in Java technology (such as Java OpenGL for access to ubiquitous fast graphics hardware, Trusted Applet for file input and output, and multithreaded ability to take advantage of modern multi-core CPUs) are incorporated into building WILSIM-GC and active, standards-aligned curricula materials guided by educational psychology theory on science learning will be developed to accompany the model. This project is funded NSF-TUES program.

  19. Hardware-in-the-Loop Co-simulation of Distribution Grid for Demand Response

    Energy Technology Data Exchange (ETDEWEB)

    Rotger-Griful, Sergi; Chatzivasileiadis, Spyros; Jacobsen, Rune H.; Stewart, Emma M.; Domingo, Javier M.; Wetter, Michael

    2016-06-20

    In modern power systems, co-simulation is proposed as an enabler for analyzing the interactions between disparate systems. This paper introduces the co-simulation platform Virtual Grid Integration Laboratory (VirGIL) including Hardware-in-the-Loop testing, and demonstrates its potential to assess demand response strategies. VirGIL is based on a modular architecture using the Functional Mock-up Interface industrial standard to integrate new simulators. VirGIL combines state-of-the-art simulators in power systems, communications, buildings, and control. In this work, VirGIL is extended with a Hardware-in-the-Loop component to control the ventilation system of a real 12-story building in Denmark. VirGIL capabilities are illustrated in three scenarios: load following, primary reserves and load following aggregation. Experimental results show that the system can track one minute changing signals and it can provide primary reserves for up-regulation. Furthermore, the potential of aggregating several ventilation systems is evaluated considering the impact at distribution grid level and the communications protocol effect.

  20. Distributed practice. The more the merrier? A randomised bronchoscopy simulation study

    OpenAIRE

    2016-01-01

    Introduction: The distribution of practice affects the acquisition of skills. Distributed practice has shown to be more effective for skills acquisition than massed training. However, it remains unknown as to which is the most effective distributed practice schedule for learning bronchoscopy skills through simulation training. This study compares two distributed practice schedules: One-day distributed practice and weekly distributed practice.Method: Twenty physicians in training were randomly...

  1. Interactions in charged colloidal suspensions: A molecular dynamics simulation study

    Science.gov (United States)

    Padidela, Uday Kumar; Behera, Raghu Nath

    2017-07-01

    Colloidal suspensions are extensively used in everyday life and find several applications in the pharmaceutical, chemical, food industries, etc. We present the classical molecular dynamics simulation results of the structural and transport properties of charged colloidal suspensions as a function of its size, charge and concentration. The system is viewed as a two-component (colloids and counterions) primitive model consisting of spherical colloid particle (macroion) and the counterions (micro-particles), which are treated explicitly. The solvent is treated as dielectric continuum. A systematic trend in the radial distribution functions g(r), potential of mean force W(r), different thermodynamic properties and diffusion coefficients is obtained as a function of colloid charge, size and concentration. An attractive minimum in W(r) is obtained at short interparticle distance.

  2. Beam equipment electromagnetic interaction in accelerators: simulation and experimental benchmarking

    CERN Document Server

    Passarelli, Andrea; Vaccaro, Vittorio Giorgio; Massa, Rita; Masullo, Maria Rosaria

    One of the most significant technological problems to achieve the nominal performances in the Large Hadron Collider (LHC) concerns the system of collimation of particle beams. The use of collimators crystals, exploiting the channeling effect on extracted beam, has been experimentally demonstrated. The first part of this thesis is about the optimization of UA9 goniometer at CERN, this device used for beam collimation will replace a part of the vacuum chamber. The optimization process, however, requires the calculation of the coupling impedance between the circulating beam and this structure in order to define the threshold of admissible intensity to do not trigger instability processes. Simulations have been performed with electromagnetic codes to evaluate the coupling impedance and to assess the beam-structure interaction. The results clearly showed that the most concerned resonance frequencies are due solely to the open cavity to the compartment of the motors and position sensors considering the crystal in o...

  3. Direct simulation Monte Carlo schemes for Coulomb interactions in plasmas

    CERN Document Server

    Dimarco, Giacomo; Pareschi, Lorenzo

    2010-01-01

    We consider the development of Monte Carlo schemes for molecules with Coulomb interactions. We generalize the classic algorithms of Bird and Nanbu-Babovsky for rarefied gas dynamics to the Coulomb case thanks to the approximation introduced by Bobylev and Nanbu (Theory of collision algorithms for gases and plasmas based on the Boltzmann equation and the Landau-Fokker-Planck equation, Physical Review E, Vol. 61, 2000). Thus, instead of considering the original Boltzmann collision operator, the schemes are constructed through the use of an approximated Boltzmann operator. With the above choice larger time steps are possible in simulations; moreover the expensive acceptance-rejection procedure for collisions is avoided and every particle collides. Error analysis and comparisons with the original Bobylev-Nanbu (BN) scheme are performed. The numerical results show agreement with the theoretical convergence rate of the approximated Boltzmann operator and the better performance of Bird-type schemes with respect to t...

  4. Simulation of the interaction of methane, carbon dioxide and coal

    Institute of Scientific and Technical Information of China (English)

    Nie Baisheng; Wang Longkang; Li Xiangchun; Wang Chao; Li Li

    2013-01-01

    Gas adsorption has an important influence on gas flow in a coal body. Research on the characteristics of coal and gas adsorption is the theoretical basis for studying gas flow in coal. In this paper, the interaction between methane, carbon dioxide and surface molecules of anthracite was simulated using the quantum chemistry method. Adsorption energy and adsorption configurations of different quantities of gas mole-cules absorbed on the coal surface were calculated. The results show that adsorption between coal and the two kinds of gas molecules is a physical adsorption process and there is an optimal configuration. Gas molecules are more easily adsorbed in the hydroxyl-containing side chain, while it is difficult for them to be adsorbed at the position of the benzene ring. Besides, carbon dioxide molecules are more readily adsorbed on the coal surface than methane molecules. The findings have an important signifi-cance in revealing the nature of gas adsorption in coal.

  5. An Educational Tool for Interactive Parallel and Distributed Processing

    DEFF Research Database (Denmark)

    Pagliarini, Luigi; Lund, Henrik Hautop

    2011-01-01

    , connectivity, topology, island modeling, user and multiuser interaction, which can hardly be found in other tools. Finally, we introduce the system of modular interactive tiles as a tool for easy, fast, and flexible hands-on exploration of these issues, and through examples show how to implement interactive...

  6. Comparison of MADE3-simulated and observed aerosol distributions with a focus on aerosol vertical profiles

    Science.gov (United States)

    Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick

    2016-04-01

    The reliability of aerosol radiative forcing estimates from climate models depends on the accuracy of simulated global aerosol distribution and composition, as well as on the models' representation of the aerosol-cloud and aerosol-radiation interactions. To help improve on previous modeling studies, we recently developed the new aerosol microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated aerosol properties to observations. Compared properties include continental near-surface aerosol component concentrations and size distributions, continental and marine aerosol vertical profiles, and nearly global aerosol optical depth. Recent studies have shown the specific importance of aerosol vertical profiles for determination of the aerosol radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total aerosol mass mixing ratios, as well as aerosol particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total

  7. Evaporation Flux Distribution of Drops on a Hydrophilic or Hydrophobic Flat Surface by Molecular Simulations.

    Science.gov (United States)

    Xie, Chiyu; Liu, Guangzhi; Wang, Moran

    2016-08-16

    The evaporation flux distribution of sessile drops is investigated by molecular dynamic simulations. Three evaporating modes are classified, including the diffusion dominant mode, the substrate heating mode, and the environment heating mode. Both hydrophilic and hydrophobic drop-substrate interactions are considered. To count the evaporation flux distribution, which is position dependent, we proposed an azimuthal-angle-based division method under the assumption of spherical crown shape of drops. The modeling results show that the edge evaporation, i.e., near the contact line, is enhanced for hydrophilic drops in all the three modes. The surface diffusion of liquid molecular absorbed on solid substrate for hydrophilic cases plays an important role as well as the space diffusion on the enhanced evaporation rate at the edge. For hydrophobic drops, the edge evaporation flux is higher for the substrate heating mode, but lower than elsewhere of the drop for the diffusion dominant mode; however, a nearly uniform distribution is found for the environment heating mode. The evidence shows that the temperature distribution inside drops plays a key role in the position-dependent evaporation flux.

  8. Enhancing food engineering education with interactive web-based simulations

    Directory of Open Access Journals (Sweden)

    Alexandros Koulouris

    2015-04-01

    Full Text Available In the traditional deductive approach in teaching any engineering topic, teachers would first expose students to the derivation of the equations that govern the behavior of a physical system and then demonstrate the use of equations through a limited number of textbook examples. This methodology, however, is rarely adequate to unmask the cause-effect and quantitative relationships between the system variables that the equations embody. Web-based simulation, which is the integration of simulation and internet technologies, has the potential to enhance the learning experience by offering an interactive and easily accessible platform for quick and effortless experimentation with physical phenomena.This paper presents the design and development of a web-based platform for teaching basic food engineering phenomena to food technology students. The platform contains a variety of modules (“virtual experiments” covering the topics of mass and energy balances, fluid mechanics and heat transfer. In this paper, the design and development of three modules for mass balances and heat transfer is presented. Each webpage representing an educational module has the following features: visualization of the studied phenomenon through graphs, charts or videos, computation through a mathematical model and experimentation.  The student is allowed to edit key parameters of the phenomenon and observe the effect of these changes on the outputs. Experimentation can be done in a free or guided fashion with a set of prefabricated examples that students can run and self-test their knowledge by answering multiple-choice questions.

  9. Hydrodynamic Simulations of the Interaction between Giant Stars and Planets

    CERN Document Server

    Staff, Jan E; Wood, Peter; Galaviz, Pablo; Passy, Jean-Claude

    2016-01-01

    We present the results of hydrodynamic simulations of the interaction between a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with a zero-age main sequence mass of 3.5 $M_\\odot$. Dynamic in-spiral timescales are of the order of few years and a few decades for the red and asymptotic giant branch stars, respectively. The planets will eventually be destroyed at a separation from the core of the giants smaller than the resolution of our simulations, either through evaporation or tidal disruption. As the planets in-spiral, the giant stars' envelopes are somewhat puffed up. Based on relatively long timescales and even considering the fact that further in-spiral should take place before the planets are destroyed, we predict that the merger would be difficult to observe, with only a relatively small, slow brightening. Very little mass is unbound in the process. These conclusions may change if the planet's orbit enhances the star's main pulsation modes. Based on the angular momentum transfer,...

  10. Collaborative Simulation Grid: Multiscale Quantum-Mechanical/Classical Atomistic Simulations on Distributed PC Clusters in the US and Japan

    Science.gov (United States)

    Kikuchi, Hideaki; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya; Iyetomi, Hiroshi; Ogata, Shuji; Kouno, Takahisa; Shimojo, Fuyuki; Tsuruta, Kanji; Saini, Subhash; Biegel, Bryan (Technical Monitor)

    2002-01-01

    A multidisciplinary, collaborative simulation has been performed on a Grid of geographically distributed PC clusters. The multiscale simulation approach seamlessly combines i) atomistic simulation backed on the molecular dynamics (MD) method and ii) quantum mechanical (QM) calculation based on the density functional theory (DFT), so that accurate but less scalable computations are performed only where they are needed. The multiscale MD/QM simulation code has been Grid-enabled using i) a modular, additive hybridization scheme, ii) multiple QM clustering, and iii) computation/communication overlapping. The Gridified MD/QM simulation code has been used to study environmental effects of water molecules on fracture in silicon. A preliminary run of the code has achieved a parallel efficiency of 94% on 25 PCs distributed over 3 PC clusters in the US and Japan, and a larger test involving 154 processors on 5 distributed PC clusters is in progress.

  11. Control of entity interactions in a hierarchical variable resolution simulation

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.R.

    1997-10-01

    There has long been interest in variable resolution modeling to support military analysis for a broad range of interest areas. Despite the ever-present desire for models of greater fidelity at the expense of analysis and computation resources, models of moderate to low fidelity are still required at many levels of decision-making. Problems can arise due to the issue of consistency among the family of models used for analysis. To address this and other problems, models of variable resolution have been suggested. However, such variable resolution architectures inherently carry their own set of issues which must be resolved in order to be useful. First, what are the structural requirements for a variable resolution model; and second, how are interactions between entities governed, especially when the entities have different resolutions? This paper addresses these issues and discusses key mechanisms needed to develop a variable resolution combat simulation that meets several core requirements for such models: seamless aggregation/disaggregation, appropriate interactions between entities of differing resolution, and control of the aggregation/disaggregation process.

  12. Control of entity interactions in a hierarchical variable resolution simulation

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.R.

    1997-08-01

    There has long been interest in variable resolution modeling to support military analysis for a broad range of interest areas. Despite the ever-present desire for models of greater fidelity at the expense of analysis and computation resources, models of moderate to low fidelity are still required at many levels of decision-making. Problems can arise due to the issue of consistency among the family of models used for analysis. To address this and other problems, models of variable resolution have been suggested. However, such variable resolution architectures inherently carry their own set of issues which must be resolved in order to be useful. First, what are the structural requirements for a variable resolution model; and second, how are interactions between entities governed, especially when the entities have different resolutions? This paper addresses these issues and discusses key mechanisms needed to develop a variable resolution combat simulation that meets several core requirements for such models: seamless aggregation/disaggregation, appropriate interactions between entities of differing resolution, and control of the aggregation/disaggregation process.

  13. Parameter specification for the degree distribution of simulated Barabási-Albert graphs

    Science.gov (United States)

    Mohd-Zaid, Fairul; Kabban, Christine M. Schubert; Deckro, Richard F.; White, Edward D.

    2017-01-01

    The degree distribution of a simulated Barabási-Albert graph under linear preferential attachment is investigated. Specifically, the parameters of the power law distribution are estimated and compared against the theoretical values derived using mean field theory. Least squares method and MLE-nonparametric method were utilized to estimate the distribution parameters on 1000 simulated Barabási-Albert graphs for edge parameter m ∈ { 2 , 4 , 6 } and size n ∈ {2k : k = 5 , 6 , … , 14 , 15 } . Goodness of fit metrics were computed on a second set of simulated graphs for the median of the estimated parameters and other hypothetical values for the distribution parameters. The results suggest that the distribution of the parameters from simulated graphs are significantly different from the theoretical distribution and is also dependent on m. Further results confirm the finding that the parameter of the power law distribution, β, increases as m increases.

  14. FluxSimulator: An R Package to Simulate Isotopomer Distributions in Metabolic Networks

    Directory of Open Access Journals (Sweden)

    Thomas W. Binsl

    2007-01-01

    Full Text Available The representation of biochemical knowledge in terms of fluxes (transformation rates in a metabolic network is often a crucial step in the development of new drugs and efficient bioreactors. Mass spectroscopy (MS and nuclear magnetic resonance spectroscopy (NMRS in combination with 13C labeled substrates are experimental techniques resulting in data that may be used to quantify fluxes in the metabolic network underlying a process. The massive amount of data generated by spectroscopic experiments increasingly requires software which models the dynamics of the underlying biological system. In this work we present an approach to handle isotopomer distributions in metabolic networks using an object-oriented programming approach, implemented using S4 classes in R. The developed package is called FluxSimulator and provides a user friendly interface to specify the topological information of the metabolic network as well as carbon atom transitions in plain text files. The package automatically derives the mathematical representation of the formulated network, and assembles a set of ordinary differential equations (ODEs describing the change of each isotopomer pool over time. These ODEs are subsequently solved numerically. In a case study FluxSimulator was applied to an example network. Our results indicate that the package is able to reproduce exact changes in isotopomer compositions of the metabolite pools over time at given flux rates.

  15. Bayesian Reconstruction of the Velocity Distribution of Weakly Interacting Massive Particles from Direct Dark Matter Detection Data

    CERN Document Server

    Shan, Chung-Lin

    2014-01-01

    In this paper, we extended our earlier work on the reconstruction of the (time-averaged) one-dimensional velocity distribution of Galactic Weakly Interacting Massive Particles (WIMPs) and introduce the Bayesian fitting procedure to the theoretically predicted velocity distribution functions. In this reconstruction process, the (rough) velocity distribution reconstructed by using raw data from direct Dark Matter detection experiments directly, i.e. measured recoil energies, with one or more different target materials, has been used as "reconstructed-input" information. By assuming a fitting velocity distribution function and scanning the parameter space based on the Bayesian analysis, the astronomical characteristic parameters, e.g. the Solar and Earth's orbital velocities, will be pinned down as the output results. Our Monte-Carlo simulations show that this Bayesian scanning procedure could reconstruct the true (input) WIMP velocity distribution function pretty precisely with negligible systematic deviations ...

  16. The Evolving Physical Processes In Interacting Galaxies Traced By Their Spectral Energy Distributions

    Science.gov (United States)

    Smith, Howard

    Mergers and interactions have profound effects on the evolution of galaxies and on the various physical processes associated with star formation and the fueling of active nuclei (AGN). There remains, however, an incomplete understanding of how interactions affect such processes or how important they are in controlling the appearance of today's universe. We propose to study 180 interacting galaxies in 101 systems spanning early to late stage mergers for which newly archived NASA data enable detailed analyses of their ultraviolet-to-far infrared (UV-FIR) spectral energy distributions (SEDs). Our goal is an improved understanding of how a wide range of key galaxy parameters vary across the interaction sequence. Our derived physical parameters will include the total optical- infrared luminosity, star formation rate, specific star formation rate, stellar mass, dust temperatures and dust masses, compactness, photo-dissociation region (PDR) fractions, and AGN contributions to the FIR SED. Our sample is taken from the Keel-Kennicutt catalog of merging galaxies (based only on apparent galaxy separations and hence free of morphological bias) and the Surace IRAS sample of bright mergers. Our sample contains virtually all bright mergers with UV-FIR data in the archives, including (but not limited to) data from missions GALEX, Swift, Spitzer, WISE, and Herschel. We will re-reduce, recalibrate, and extract the photometry in up to 23 wavelength bands from the UV to the FIR. Our analysis plan emphasizes three new SED modeling tools, one of which we have recently developed. Nearly all of the sources also have Spitzer IRS spectral data (primarily of the circumnuclear regions), and we will use the IRS data to supplement the SED conclusions via our own algorithm which also infers metallicity, interstellar medium (ISM) ambient pressure, and embedded young star fractions. Finally, we will compare each merger to the simulated photometry/ morphology of a suite of simulations based on

  17. Simulating SAL formation and aerosol size distribution during SAMUM-I

    KAUST Repository

    Khan, Basit Ali

    2015-04-01

    To understand the formation mechanisms of Saharan Air Layer (SAL), we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF-Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground-based observations show that WRF-Chem reproduces observed meteorological fields as well as aerosol spatial distribution across the entire region and along the airplane\\'s tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface-detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground-based observations are generally good, but suggest that more detailed treatment of microphysics in the model is required to capture the full-scale effect of large aerosol particles.

  18. Investigating the effect of surface water - groundwater interactions on stream temperature using Distributed temperature sensing and instream temperature model

    DEFF Research Database (Denmark)

    Karthikeyan, Matheswaran; Blemmer, Morten; Mortensen, Julie Flor;

    2011-01-01

    Surface water–groundwater interactions at the stream interface influences, and at times controls the stream temperature, a critical water property driving biogeochemical processes. This study investigates the effects of these interactions on temperature of Stream Elverdamsåen in Denmark using...... the Distributed Temperature Sensing (DTS) system and instream temperature modelling. Locations of surface water–groundwater interactions were identified from the temperature data collected over a 2-km stream reach using a DTS system with 1-m spatial and 5-min temporal resolution. The stream under consideration...... exhibits three distinct thermal regimes within a 2 km reach length due to two major interactions. An energy balance model is used to simulate the instream temperature and to quantify the effect of these interactions on the stream temperature. This research demonstrates the effect of reach level small scale...

  19. Trophallaxis-inspired model for distributed transport between randomly interacting agents

    Science.gov (United States)

    Gräwer, Johannes; Ronellenfitsch, Henrik; Mazza, Marco G.; Katifori, Eleni

    2017-08-01

    Trophallaxis, the regurgitation and mouth to mouth transfer of liquid food between members of eusocial insect societies, is an important process that allows the fast and efficient dissemination of food in the colony. Trophallactic systems are typically treated as a network of agent interactions. This approach, though valuable, does not easily lend itself to analytic predictions. In this work we consider a simple trophallactic system of randomly interacting agents with finite carrying capacity, and calculate analytically and via a series of simulations the global food intake rate for the whole colony as well as observables describing how uniformly the food is distributed within the nest. Our model and predictions provide a useful benchmark to assess to what level the observed food uptake rates and efficiency in food distribution is due to stochastic effects or specific trophallactic strategies by the ant colony. Our work also serves as a stepping stone to describing the collective properties of more complex trophallactic systems, such as those including division of labor between foragers and workers.

  20. Baryonic and dark matter distribution in cosmological simulations of spiral galaxies

    CERN Document Server

    Mollitor, Pol; Teyssier, Romain

    2014-01-01

    We study three high resolution cosmological hydrodynamical simulations of Milky Way-sized halos including a comparison with the corresponding DM-only counterparts performed with the adaptive mesh refinement code RAMSES. We analyse the stellar and the gas distribution and find one of our simulated galaxies with interesting Milky Way-like features with regard to several observational tests. Thanks to consistently tuned star formation rate and supernovae feedback, we manage to obtain an extended disk and a flat rotation curve with a circular velocity and a dark matter density in the solar neighbourhood in agreement with observations. With a careful look at the derivation of the stellar-to-halo mass ratio, we also obtain competitive values for this criterion. Concerning the dark matter distribution, we explicitly show the interaction with the baryons and show how the dark matter is first contracted by star formation and then cored by feedback processes. Analysing the clump spectrum, we find a shift in mass with r...

  1. Numerical simulation of unsteady interaction of centrifugal impeller with its diffuser using Lagrangian discrete vortex method

    Institute of Scientific and Technical Information of China (English)

    Baoshan Zhu; Kyoji Kamemoto

    2005-01-01

    In this study, an advanced Lagrangian vortexboundary element method is applied to simulate the unsteady impeller-diffuser interactions in a diffuser pump not only for design but also for off-design considerations. In velocity calculations based on the Biot-Savart law we do not have to grid large portions of the flow field and the calculation points are concentrated in the regions where vorticity is present.Lagrangian representation of the evolving vorticity field is well suited to moving boundaries. An integral pressure equation shows that the pressure distribution can be estimated directly from the instantaneous velocity and vorticity field.The numerical results are compared with the experimental data and the comparisons show that the method used in this study can provide us insight into the complicated unsteady impeller-diffuser interaction phenomena in a diffuser pump.

  2. Simulation of a class of delay stochastic system with distributed parameter

    Institute of Scientific and Technical Information of China (English)

    Song Yanan; Deng Feiqi; Luo Qi

    2005-01-01

    Simulation of a class of delay stochastic system with distributed parameter is discussed. Difference schemes for the numerical computation of delay stochastic system are obtained. The precision of the difference scheme and the efficiency of the difference scheme in simulation of delay stochastic system with distributed parameter are analyzed. Examples are given to illustrate the application of the method.

  3. Jovian plasma torus interaction with Europa. Plasma wake structure and effect of inductive magnetic field: 3D Hybrid kinetic simulation

    CERN Document Server

    Lipatov, A S; Paterson, W R; Sittler, E C; Hartle, R E; Simpson, D G

    2012-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect a to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream backgr...

  4. Distributed-Order Dynamic Systems Stability, Simulation, Applications and Perspectives

    CERN Document Server

    Jiao, Zhuang; Podlubny, Igor

    2012-01-01

    Distributed-order differential equations, a generalization of fractional calculus, are of increasing importance in many fields of science and engineering from the behaviour of complex dielectric media to the modelling of nonlinear systems. This Brief will broaden the toolbox available to researchers interested in modeling, analysis, control and filtering. It contains contextual material outlining the progression from integer-order, through fractional-order to distributed-order systems. Stability issues are addressed with graphical and numerical results highlighting the fundamental differences between constant-, integer-, and distributed-order treatments. The power of the distributed-order model is demonstrated with work on the stability of noncommensurate-order linear time-invariant systems. Generic applications of the distributed-order operator follow: signal processing and viscoelastic damping of a mass–spring set up. A new general approach to discretization of distributed-order derivatives and integrals ...

  5. Multiagent-Based Simulation of Temporal-Spatial Characteristics of Activity-Travel Patterns Using Interactive Reinforcement Learning

    Directory of Open Access Journals (Sweden)

    Min Yang

    2014-01-01

    Full Text Available We propose a multiagent-based reinforcement learning algorithm, in which the interactions between travelers and the environment are considered to simulate temporal-spatial characteristics of activity-travel patterns in a city. Road congestion degree is added to the reinforcement learning algorithm as a medium that passes the influence of one traveler’s decision to others. Meanwhile, the agents used in the algorithm are initialized from typical activity patterns extracted from the travel survey diary data of Shangyu city in China. In the simulation, both macroscopic activity-travel characteristics such as traffic flow spatial-temporal distribution and microscopic characteristics such as activity-travel schedules of each agent are obtained. Comparing the simulation results with the survey data, we find that deviation of the peak-hour traffic flow is less than 5%, while the correlation of the simulated versus survey location choice distribution is over 0.9.

  6. Iteration method for the inversion of simulated multiwavelength lidar signals to determine aerosol size distribution

    Institute of Scientific and Technical Information of China (English)

    Tao Zong-Ming; Zhang Yin-Chao; Liu Xiao-Qin; Tan Kun; Shao Shi-Sheng; Hu Huan-Ling; Zhang Gai-Xia; Lü Yong-Hui

    2004-01-01

    A new method is proposed to derive the size distribution of aerosol from the simulated multiwavelength lidar extinction coefficients. The basis for this iteration is to consider the extinction efficiency factor of particles as a set of weighting function covering the entire radius region of a distribution. The weighting functions are calculated exactly from Mie theory. This method extends the inversion region by subtracting some extinction coefficient. The radius range of simulated size distribution is 0.1-10.0μm, the inversion radius range is 0.1-2.0μm, but the inverted size distributions are in good agreement with the simulated one.

  7. Molecular simulation of carbon dioxide, brine, and clay mineral interactions and determination of contact angles.

    Science.gov (United States)

    Tenney, Craig M; Cygan, Randall T

    2014-01-01

    Capture and subsequent geologic storage of CO2 in deep brine reservoirs plays a significant role in plans to reduce atmospheric carbon emission and resulting global climate change. The interaction of CO2 and brine species with mineral surfaces controls the ultimate fate of injected CO2 at the nanoscale via geochemistry, at the pore-scale via capillary trapping, and at the field-scale via relative permeability. We used large-scale molecular dynamics simulations to study the behavior of supercritical CO2 and aqueous fluids on both the hydrophilic and hydrophobic basal surfaces of kaolinite, a common clay mineral. In the presence of a bulk aqueous phase, supercritical CO2 forms a nonwetting droplet above the hydrophilic surface of kaolinite. This CO2 droplet is separated from the mineral surface by distinct layers of water, which prevent the CO2 droplet from interacting directly with the mineral surface. Conversely, both CO2 and H2O molecules interact directly with the hydrophobic surface of kaolinite. In the presence of bulk supercritical CO2, nonwetting aqueous droplets interact with the hydrophobic surface of kaolinite via a mixture of adsorbed CO2 and H2O molecules. Because nucleation and precipitation of minerals should depend strongly on the local distribution of CO2, H2O, and ion species, these nanoscale surface interactions are expected to influence long-term mineralization of injected carbon dioxide.

  8. Interaction of ring current and radiation belt protons with ducted plasmaspheric hiss. 2. Time evolution of the distribution function

    Science.gov (United States)

    Kozyra, J. U.; Rasmussen, C. E.; Miller, R. H.; Villalon, E.

    1995-11-01

    The evolution of the bounce-averaged ring current/radiation belt proton distribution is simulated during resonant interactions with ducted plasmaspheric hiss. The plasmaspheric hiss is assumed to be generated by ring current electrons and to be damped by the energetic protons. Thus energy is transferred between energetic electrons and protons using the plasmaspheric hiss as a mediary. The problem is not solved self-consistently. During the simulation period, interactions with ring current electrons (not represented in the model) are assumed to maintain the wave amplitudes in the presence of damping by the energetic protons, allowing the wave spectrum to be held fixed. Diffusion coefficients in pitch angle, cross pitch angle/energy, and energy were previously calculated by Kozyra et al. (1994) and are adopted for the present study. The simulation treats the energy range, E>=80 keV, within which the wave diffusion operates on a shorter timescale than other proton loss processes (i.e., Coulomb drag and charge exchange). These other loss processes are not included in the simulation. An interesting result of the simulation is that energy diffusion maximizes at moderate pitch angles near the edge of the atmospheric loss cone. Over the simulation period, diffusion in energy creates an order of magnitude enhancement in the bounce-averaged proton distribution function at moderate pitch angles. The loss cone is nearly empty because scattering of particles at small pitch angles is weak. The bounce-averaged flux distribution, mapped to ionospheric heights, results in elevated locally mirroring proton fluxes. OGO 5 observed order of magnitude enhancements in locally mirroring energetic protons at altitudes between 350 and 1300 km and invariant latitudes between 50° and 60° (Lundblad and Soraas, 1978). The proton distributions were highly anisotropic in pitch angle with nearly empty loss cones. The similarity between the observed distributions and those resulting from this

  9. CONCEPTUAL CATEGORIES FOR THE STUDY OF Strategic KNOWLEDGE USED WHEN INTERACTING WITH EDUCATIONAL SIMULATIONS

    Directory of Open Access Journals (Sweden)

    María José Bouciguez

    2010-11-01

    Full Text Available In this paper, we introduce some relationships between elements coming from psychological referentials with the purpose of developing a referential framework for interpreting and understanding the actions that take place during school practices with computer simulations that include, in addition to concepts of the learning process of a particular discipline, concepts that refer to social relationships, not only interactions among people but also between people with to culture, social institutions and social structure. From a social constructivist approach is proposed to constitute the object of study in the system “person + tool” in the situated context in the learning of science in the school, in order to obtain categories that allow us investigate the strategic knowledge employed by the students when they use educational simulations and the influence of the latter in science learning. We believe that the study of the strategic knowledge performed by the students in science classes when they interact with computer simulations is an issue of the technological mediation of learning. For that reason, from the socio-historical perspective we have selected the following categories: instrumental mediation, the distributed character of cognition, the zone of proximal development and the situated character of cognition.

  10. Structures and orientation-dependent interaction forces of titania nanowires using molecular dynamics simulations

    Science.gov (United States)

    Okeke, George; Antony, S. Joseph; Hammond, Robert B.; Ahmed, Kamran

    2017-07-01

    Engineering nanowires to develop new products and processes is highly topical due to their ability to provide highly enhanced physical, chemical, mechanical, thermal and electrical properties. In this work, using molecular dynamics simulations, we report fundamental information, about the structural and thermodynamic properties of individual anatase titania (TiO2) nanowires with cross-sectional diameters between 2 and 6 nm, and aspect ratio (length to diameter) of 6:1 at temperatures ranging from 300 to 3000 K. Estimates of the melting transition temperature of the nanowires are between 2000 and 2500 K. The melting transition temperature predicted from the radial distribution functions (RDFs) shows strong agreement with those predicted from the total energy profiles. Overall, the transition temperature is in reasonable agreement with melting points predicted from experiments and simulations reported in the literature for spherical nanoparticles of similar sizes. Hence, the melting transition temperature of TiO2 nanowires modelled here can be considered as shape independent. Furthermore, for the first time based on MD simulations, interaction forces between two nanowires are reported at ambient temperature (300 K) for different orientations: parallel, perpendicular and end-to-end. It is observed that end-to-end orientations manifested the strongest attraction forces, while the parallel and perpendicular orientations displayed weaker attractions. The results reported here could form a foundation in future multiscale modelling studies of the structured titania nanowire assemblies, depending on the inter-wire interaction forces.

  11. Cloud Service for Interactive Simulation of Interregional Trade

    Directory of Open Access Journals (Sweden)

    A. S. Velichko

    2016-01-01

    Full Text Available The paper describes a mathematical model of trade flows between the territories of a region or a country in a transport network having one or more different types of marine or ground transportation. We use the approach of modeling complex communication systems to determine the most probable values of flows in case of incomplete information about the system. Transport costs between the territories are modeled within the framework of the gravity model. The payment for transportation depends on the distance between regions, the distance is estimated as the shortest way length in a given transport network or geographical distance. The mathematical formulation of the problem belongs to the class of convex mathematical programming problems and assumes the numerical solution of nonlinear optimization problem with linear constraints. Based on the model, the software is implemented as a cloud service on heterogeneous computing architectures: the simulation module is made on a highperformance server platform, management and visualization modules are produced with IACPaaS cloud platform. Communication between the platforms is established via asynchronous http-queries. For information exchange between the modules the declarative model with JSON format is developed and implemented for the objects considered in the mathematical model which are products, areas and communications. Visualization module allows to present graphically the original and the resulting matrix data and to modify the input parameters of the model interactively. The paper demonstrates the use of software for the simulation of inter-regional freight traffic of the Russian Far East region based on input data provided by open statistics sources.

  12. Modeling the Dynamics of Interacting Galaxy Pairs - Testing Identikit Using GADGET SPH Simulations

    Science.gov (United States)

    Mortazavi, S. Alireza; Lotz, Jennifer; Barnes, Joshua E.

    2015-01-01

    We develop and test an automated technique to model the dynamics of interacting galaxy pairs. We use Identikit (Barnes & Hibbard 2009; Barnes 2011) as a tool for modeling and matching the morphology and kinematics of the interacting pairs of similar-size galaxies. In order to reduce the effect of subjective human interference, we automate the selection of phase-space regions used to match simulations to data, and we explore how selection of these regions affects the random uncertainties of parameters in the best-fit model. In this work, we used an independent set of GADGET SPH simulations as input data, so we determined the systematic bias in the measured encounter parameters based on the known initial conditions of these simulations. We tested both cold gas and young stellar components in the GADGET simulations to explore the effect of choosing HI vs. Hα as the line of sight velocity tracer. We found that we can group the results into tests with good, fair, and poor convergence based on the distribution of parameters of models close enough to the best-fit model. For tests with good and fair convergence, we ruled out large fractions of parameter space and recovered merger stage, eccentricity, viewing angle, and pericentric distance within 2σ of the correct value. All of tests on gaseous component of prograde systems had either good or fair convergence. Retrograde systems and most of tests on young stars had poor convergence and may require constraints from regions other than the tidal tails. In this work we also present WIYN SparsePak IFU data for a few interacting galaxies, and we show the result of applying our method on this data set.

  13. Numerical simulations and measurements of a droplet size distribution in a turbulent vortex street

    Directory of Open Access Journals (Sweden)

    Ellen Schmeyer

    2014-09-01

    Full Text Available A turbulent vortex street in an air flow interacting with a disperse droplet population is investigated in a wind tunnel. Non-intrusive measurement techniques are used to obtain data for the air velocity and the droplet velocity. The process is modeled with a population balance system consisting of the incompressible Navier-Stokes equations and a population balance equation for the droplet size distribution. Numerical simulations are performed that rely on a variational multiscale method for turbulent flows, a direct discretization of the differential operator of the population balance equation, and a modern technique for the evaluation of the coalescence integrals. After having calibrated two unknown model parameters, a very good agreement of the experimental and numerical results can be observed.

  14. Galaxy pairs in cosmological simulations: effects of interactions on colours and chemical abundances

    CERN Document Server

    Perez, M J; Lambas, D G; Scannapieco, C; Tissera, P B; Lambas, Diego G.; Rossi, Maria E. De; Scannapieco, Cecilia; Tissera, Patricia B.

    2006-01-01

    We perform an statistical analysis of galaxies in pairs in a Lambda-CDM scenario by using the chemical GADGET-2 of Scannapieco et al. (2005) in order to study the effects of galaxy interactions on colours and metallicities. We find that galaxy-galaxy interactions can produce a bimodal colour distribution with galaxies with significant recent star formation activity contributing mainly to blue colours. In the simulations, the colours and the fractions of recently formed stars of galaxies in pairs depend on environment more strongly than those of galaxies without a close companion, suggesting that interactions play an important role in galaxy evolution. If the metallicity of the stellar populations is used as the chemical indicator, we find that the simulated galaxies determine luminosity-metallicity and stellar mass-metallicity relations which do not depend on the presence of a close companion. However, in the case of the luminosity-metallicity relation, at a given level of enrichment, we detect a systematic d...

  15. The Astrophysics Simulation Collaboratory portal: A framework foreffective distributed research

    Energy Technology Data Exchange (ETDEWEB)

    Bondarescu, Ruxandra; Allen, Gabrielle; Daues, Gregory; Kelly,Ian; Russell, Michael; Seidel, Edward; Shalf, John; Tobias, Malcolm

    2003-03-03

    We describe the motivation, architecture, and implementation of the Astrophysics Simulation Collaboratory (ASC) portal. The ASC project provides a web-based problem solving framework for the astrophysics community that harnesses the capabilities of emerging computational grids.

  16. Migrating to a real-time distributed parallel simulator architecture

    CSIR Research Space (South Africa)

    Duvenhage, B

    2007-07-01

    Full Text Available DEVS. Ogata, et al. [7] tested the real-time performance of DIS and different versions of the RTI-NG HLA Run-Time Infrastructure (RTI). Their real-time vehicle model simulation within a 3D graphi- cal environment reached a frame rate ceiling... to mili- tary training simulation: A guide for discrete event sim- ulationists. In Proceedings of the 1998 Winter Simula- tion Conference, 1998. [7] Michihiko Ogata, Akira Higashide, Mike Cammarano, and Toshinao Takagi. Rti performance...

  17. High-energy tail distributions and resonant wave particle interaction

    Science.gov (United States)

    Leubner, M. P.

    1983-01-01

    High-energy tail distributions (k distributions) are used as an alternative to a bi-Lorentzian distribution to study the influence of energetic protons on the right- and left-hand cyclotron modes in a hot two-temperature plasma. Although the parameters are chosen to be in a range appropriate to solar wind or magnetospheric configurations, the results apply not only to specific space plasmas. The presence of energetic particles significantly alters the behavior of the electromagnetic ion cyclotron modes, leading to a wide range of unstable frequencies and increased growth rates. From the strongly enhanced growth rates it can be concluded that high-energy tail distributions should not show major temperature anisotropies, which is consistent with observations.

  18. Distributed energy resources in grid interactive AC microgrids

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Guerrero, Josep; Chen, Zhe

    2010-01-01

    Increased penetration of distributed energy resources (DER) and large-scale deployment of renewable energy sources are challenging the entire architecture of traditional power system. Microgrid, featuring higher flexibility and reliability, becomes an attractive candidate for the configuration of...

  19. Interactive Graphics Simulator: Design, Development, and Effectiveness/Cost Evaluation. Final Report.

    Science.gov (United States)

    Pieper, William J.; And Others

    This study was initiated to design, develop, implement, and evaluate a videodisc-based simulator system, the Interactive Graphics Simulator (IGS) for 6883 Converter Flight Control Test Station training at Lowry Air Force Base, Colorado. The simulator provided a means for performing task analysis online, developing simulations from the task…

  20. Quantum Monte Carlo simulations of bosons with complex interactions

    Science.gov (United States)

    Rousseau, Valery

    2015-03-01

    Many of the most exciting materials and phenomena being studied today, from oxide heterostructures to topological insulators or iron-based superconductors, are the ones in which an understanding of how quantum particles interact with each other is essential. In the last decade, the development and the improvement of quantum Monte Carlo algorithms combined with the increased power of computers has opened the way to the exact simulation of Hamiltonians that include various types of interactions, such as inter-species conversion terms or ring-exchange terms. Simultaneously, developments made in the field of optical lattices, laser cooling and magneto/optical trapping techniques have led to ideal realizations of such Hamiltonians. A wide variety of phases can be present, including Mott insulators and superfluids, as well as more exotic phases such as Haldane insulators, supersolids, counter-superfluids, or the recently proposed Feshbach insulator. These experimental realizations of the various forms of the Hubbard model can have interesting applications, in particular they provide a possible way of performing quantum computing, and have also given rise to a new field known as Atomtronics, the equivalent of Electronics where the carriers are replaced by atoms. I will illustrate these ideas with examples of Hamiltonians that have been studied and some results. In order to study these systems, it is crucial to identify the various phases that are present, which can be characterized by a set of order parameters. Of particular importance in this task is the superfluid density. It is well known that the superfluid density can be related to the response of the free energy to a boundary phase twist, or to the fluctuations of the winding number. However, these relationships break down when complex interactions are involved. To address this problem, I will propose a general expression of the superfluid density, derived from real and thought experiments. I will discuss two

  1. Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

    CERN Document Server

    Churmakov, D Y; Piletsky, S A; Greenhalgh, D A

    2003-01-01

    A novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account the spatial distribution of fluorophores, which would arise due to the structure of collagen fibres, compared to the epidermis and stratum corneum where the distribution of fluorophores is assumed to be homogeneous. The results of simulation suggest that distribution of auto- fluorescence is significantly suppressed in the near-infrared spectral region, whereas the spatial distribution of fluorescence sources within a sensor layer embedded in the epidermis is localized at an effective depth.

  2. Analysis of skin tissues spatial fluorescence distribution by the Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Churmakov, D Y [School of Engineering, Cranfield University, Cranfield, MK43 0AL (United Kingdom); Meglinski, I V [School of Engineering, Cranfield University, Cranfield, MK43 0AL (United Kingdom); Piletsky, S A [Institute of BioScience and Technology, Cranfield University, Silsoe, MK45 4DT (United Kingdom); Greenhalgh, D A [School of Engineering, Cranfield University, Cranfield, MK43 0AL (United Kingdom)

    2003-07-21

    A novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account the spatial distribution of fluorophores, which would arise due to the structure of collagen fibres, compared to the epidermis and stratum corneum where the distribution of fluorophores is assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed in the near-infrared spectral region, whereas the spatial distribution of fluorescence sources within a sensor layer embedded in the epidermis is localized at an 'effective' depth.

  3. Implementation of interactive virtual simulation of physical systems

    Science.gov (United States)

    Sanchez, H.; Escobar, J. J.; Gonzalez, J. D.; Beltran, J.

    2014-03-01

    Considering the limited availability of laboratories for physics teaching and the difficulties this causes in the learning of school students in Santa Marta Colombia, we have developed software in order to generate greater student interaction with the phenomena physical and improve their understanding. Thereby, this system has been proposed in an architecture Model/View- View- Model (MVVM), sharing the benefits of MVC. Basically, this pattern consists of 3 parts: The Model, that is responsible for business logic related. The View, which is the part with which we are most familiar and the user sees. Its role is to display data to the user and allowing manipulation of the data of the application. The ViewModel, which is the middle part of the Model and the View (analogous to the Controller in the MVC pattern), as well as being responsible for implementing the behavior of the view to respond to user actions and expose data model in a way that is easy to use links to data in the view. .NET Framework 4.0 and editing package Silverlight 4 and 5 are the main requirements needed for the deployment of physical simulations that are hosted in the web application and a web browser (Internet Explorer, Mozilla Firefox or Chrome). The implementation of this innovative application in educational institutions has shown that students improved their contextualization of physical phenomena.

  4. Simulated Interactive Research Experiments as Educational Tools for Advanced Science

    Science.gov (United States)

    Tomandl, Mathias; Mieling, Thomas; Losert-Valiente Kroon, Christiane M.; Hopf, Martin; Arndt, Markus

    2015-09-01

    Experimental research has become complex and thus a challenge to science education. Only very few students can typically be trained on advanced scientific equipment. It is therefore important to find new tools that allow all students to acquire laboratory skills individually and independent of where they are located. In a design-based research process we have investigated the feasibility of using a virtual laboratory as a photo-realistic and scientifically valid representation of advanced scientific infrastructure to teach modern experimental science, here, molecular quantum optics. We found a concept based on three educational principles that allows undergraduate students to become acquainted with procedures and concepts of a modern research field. We find a significant increase in student understanding using our Simulated Interactive Research Experiment (SiReX), by evaluating the learning outcomes with semi-structured interviews in a pre/post design. This suggests that this concept of an educational tool can be generalized to disseminate findings in other fields.

  5. Numerical Simulation of Tower Rotor Interaction for Downwind Wind Turbine

    Directory of Open Access Journals (Sweden)

    Isam Janajreh

    2010-01-01

    Full Text Available Downwind wind turbines have lower upwind rotor misalignment, and thus lower turning moment and self-steered advantage over the upwind configuration. In this paper, numerical simulation to the downwind turbine is conducted to investigate the interaction between the tower and the blade during the intrinsic passage of the rotor in the wake of the tower. The moving rotor has been accounted for via ALE formulation of the incompressible, unsteady, turbulent Navier-Stokes equations. The localized CP, CL, and CD are computed and compared to undisturbed flow evaluated by Panel method. The time history of the CP, aerodynamic forces (CL and CD, as well as moments were evaluated for three cross-sectional tower; asymmetrical airfoil (NACA0012 having four times the rotor's chord length, and two circular cross-sections having four and two chords lengths of the rotor's chord. 5%, 17%, and 57% reductions of the aerodynamic lift forces during the blade passage in the wake of the symmetrical airfoil tower, small circular cross-section tower and large circular cross-section tower were observed, respectively. The pronounced reduction, however, is confined to a short time/distance of three rotor chords. A net forward impulsive force is also observed on the tower due to the high speed rotor motion.

  6. Numerical simulation of a compressible vortex-wall interaction

    Science.gov (United States)

    Murugan, T.; De, S.; Sreevatsa, A.; Dutta, S.

    2016-05-01

    The wall interaction of isolated compressible vortices generated from a short driver section shock tube has been simulated numerically by solving the Navier-Stokes equations in axisymmetric form. The dynamics of shock-free (incident shock Mach number M = 1.36) and shock-embedded (M = 1.57) compressible vortices near the wall has been studied in detail. The AUSM+ scheme with a fifth-order upwind interpolation formula is used for the convective fluxes. Time integration is performed using a low dissipative and dispersive fourth-order six-stage Runge-Kutta scheme. The evolution of primary and wall vortices has been shown using the velocity field, vorticity field, and numerical schlierens. The vortex impingement, shocklets, wall vortices, and their lift-off are clearly identified from the wall pressure time history. It has been observed that the maximum vorticity of the wall vortices reaches close to 30 % of the primary vortex for M = 1.36 and it reaches up to 60 % for M = 1.57. The net pressure force on the wall due to incident shock impingement is dominant compared to the compressible vortex impingement and their evolution.

  7. Computer Simulations for Top Flavor-changing Neutral Higgs Interactions

    Science.gov (United States)

    Sloan, Jackson; Kao, Chung; Jain, Rishabh; McCoy, Brent

    2017-01-01

    Two-Higgs-doublet models (2HDM) are natural extensions to the Standard Model (SM), and a general 2HDM allows tree-level flavor-changing neutral currents (FCNC). We choose this model for our analysis. Since the top quark is heavier than the light Higgs, t -> ch is kinematically possible, and a tch coupling is an accessible example of an FCNC. We look to FCNCs to study physics beyond the Standard Model, and, more specifically, to examine the potential for discovery of a flavor-changing neutral Higgs (FCNH) interaction at the LHC. We examine the discovery potential for the processes pp -> th -> bjjWW -> bjjlνlν + X and pp -> t t -> bjjcWW + X , using MadGraph to generate parton level calculations, Pythia for showering and hadronization, and Delphes for detector simulation. We use ROOT analysis to reconstruct the transverse mass mT (ll ,ET) . We examine these processes and present event rates and significance of the Higgs signal, including SM physics background with realistic acceptance cuts for √{ s} = 13 TeV and √{ s} = 14 TeV. This research was funded in part by NSF award PHY-1359417.

  8. Simulated Interactive Research Experiments as Educational Tools for Advanced Science

    Science.gov (United States)

    Tomandl, Mathias; Mieling, Thomas; Losert-Valiente Kroon, Christiane M.; Hopf, Martin; Arndt, Markus

    2015-01-01

    Experimental research has become complex and thus a challenge to science education. Only very few students can typically be trained on advanced scientific equipment. It is therefore important to find new tools that allow all students to acquire laboratory skills individually and independent of where they are located. In a design-based research process we have investigated the feasibility of using a virtual laboratory as a photo-realistic and scientifically valid representation of advanced scientific infrastructure to teach modern experimental science, here, molecular quantum optics. We found a concept based on three educational principles that allows undergraduate students to become acquainted with procedures and concepts of a modern research field. We find a significant increase in student understanding using our Simulated Interactive Research Experiment (SiReX), by evaluating the learning outcomes with semi-structured interviews in a pre/post design. This suggests that this concept of an educational tool can be generalized to disseminate findings in other fields. PMID:26370627

  9. Simulated Interactive Research Experiments as Educational Tools for Advanced Science.

    Science.gov (United States)

    Tomandl, Mathias; Mieling, Thomas; Losert-Valiente Kroon, Christiane M; Hopf, Martin; Arndt, Markus

    2015-09-15

    Experimental research has become complex and thus a challenge to science education. Only very few students can typically be trained on advanced scientific equipment. It is therefore important to find new tools that allow all students to acquire laboratory skills individually and independent of where they are located. In a design-based research process we have investigated the feasibility of using a virtual laboratory as a photo-realistic and scientifically valid representation of advanced scientific infrastructure to teach modern experimental science, here, molecular quantum optics. We found a concept based on three educational principles that allows undergraduate students to become acquainted with procedures and concepts of a modern research field. We find a significant increase in student understanding using our Simulated Interactive Research Experiment (SiReX), by evaluating the learning outcomes with semi-structured interviews in a pre/post design. This suggests that this concept of an educational tool can be generalized to disseminate findings in other fields.

  10. DISCOS- DYNAMIC INTERACTION SIMULATION OF CONTROLS AND STRUCTURES (IBM VERSION)

    Science.gov (United States)

    Frisch, H. P.

    1994-01-01

    The Dynamic Interaction Simulation of Controls and Structure (DISCOS) program was developed for the dynamic simulation and stability analysis of passive and actively controlled spacecraft. In the use of DISCOS, the physical system undergoing analysis may be generally described as a cluster of contiguous flexible structures (bodies) that comprise a mechanical system, such as a spacecraft. The entire system (spacecraft) or portions thereof may be either spinning or nonspinning. Member bodies of the system may undergo large relative excursions, such as those of appendage deployment or rotor/ stator motion. The general system of bodies is, by its inherent nature, a feedback system in which inertial forces (such as those due to centrifugal and Coriolis acceleration) and the restoring and damping forces are motion-dependent. The system may possess a control system in which certain position and rate errors are actively controlled through the use of reaction control jets, servomotors, or momentum wheels. Bodies of the system may be interconnected by linear or nonlinear springs and dampers, by a gimbal and slider block mechanism, or by any combination of these. The DISCOS program can be used to obtain nonlinear and linearized time response of the system, interaction constant forces in the system, total system resonance properties, and frequency domain response and stability information for the system. DISCOS is probably the most powerful computational tool to date for the computer simulation of actively controlled coupled multi-flexible-body systems. The program is not easy to understand and effectively apply, but is not intended for simple problems. The DISCOS user is expected to have extensive working knowledge of rigid-body and flexible-body dynamics, finite-element techniques, numerical methods, and frequency-domain analysis. Various applications of DISCOS include simulation of the Shuttle payload deployment/retrieval mechanism, solar panel array deployment, antenna

  11. Numerical simulation of red blood cell distributions in three-dimensional microvascular bifurcations.

    Science.gov (United States)

    Hyakutake, Toru; Nagai, Shinya

    2015-01-01

    We constructed three-dimensional microvascular bifurcation models using a parent vessel of diameter 10μm and investigated the flow behavior of the red blood cells (RBCs) through bifurcations. We considered symmetric and asymmetric model types. Two cases of equal daughter vessel diameter were employed for the asymmetric models, where the first was 10μm, which is the same as the parent vessel and the second was 7.94μm, which satisfies Murray's law. Simulated blood flow was computed using the lattice Boltzmann method in conjunction with the immersed boundary method for incorporating fluid-membrane interactions between the flow field and deformable RBCs. First, we investigated the flow behavior of a single RBC through microvascular bifurcations. In the case of the symmetric bifurcation, the turning point of the fractional plasma flow wherein the RBC flow changed from one daughter vessel to the other was 0.50. This turning point was however different for asymmetric bifurcations. Additionally, we varied the initial offset of RBCs from the centerline of the parent vessel. The simulation results indicated that the RBCs preferentially flow through the branch of a larger flow ratio. Next, we investigated the distribution characteristics of multiple RBCs. Simulations indicated that the results of the symmetric model were similar to those predicted by a previously published empirical model. On the other hand, results of asymmetric models deviated from those of the symmetric and empirical models. These results suggest that the distribution of RBCs varies according to the bifurcation angle and daughter vessel diameter in a microvascular bifurcation of the size considered.

  12. Flight Dynamic Simulation with Nonlinear Aeroelastic Interaction using the ROM-ROM Procedure Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. (ZONA) proposes to develop an integrated flight dynamics simulation capability with nonlinear aeroelastic interactions by combining a flight...

  13. Flight Dynamic Simulation with Nonlinear Aeroelastic Interaction using the ROM-ROM Procedure Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZONA Technology, Inc. proposes to develop an integrated flight dynamics simulation capability with nonlinear aeroelastic interactions by combining a flight dynamics...

  14. Simulation research of location mechanism of chaotic distributed optical fiber sensing system

    Science.gov (United States)

    Guo, Sujie; Fang, Nian; Wang, Lutang; Huang, Zhaoming

    2016-01-01

    A distributed optical fiber sensing system based on a bidirectional chaotic fiber ring laser has been proposed. The output waveforms induced by an external disturbance in some period are different from those in other time. This period equals the time difference between two counter-propagating beams arriving at the semiconductor optical amplifier (SOA) from the disturbance point. It is utilized for the disturbance location. In this paper, the location mechanism is explored by investigating optical interaction in the SOA in two simulation systems with a continuous wave optical source. One system is for studying the interaction of a continuous wave beam and a phase modulation beam input into the SOA from the left and right sides respectively. The other system is for investigating the interaction of two phase modulation beams counter-arriving at the SOA with a certain time difference. Under a small SOA current, only the transformation of the phase modulation to intensity modulation occurs due to the interference caused by facets reflection of the SOA. With the increase of current, the cross-gain modulation effect of the SOA makes the interference signal in one beam copy to the other one reversely in the phase, which generates the time difference characteristic. For the chaotic sensing system the situation is similar to the large current case in the second simulation system, only the conversion of the modulation format is achieved by the sensitivity to initial values of chaotic systems. The cross-gain modulation effect in the SOA contributes to the time difference location method.

  15. A distributed computing tool for generating neural simulation databases.

    Science.gov (United States)

    Calin-Jageman, Robert J; Katz, Paul S

    2006-12-01

    After developing a model neuron or network, it is important to systematically explore its behavior across a wide range of parameter values or experimental conditions, or both. However, compiling a very large set of simulation runs is challenging because it typically requires both access to and expertise with high-performance computing facilities. To lower the barrier for large-scale model analysis, we have developed NeuronPM, a client/server application that creates a "screen-saver" cluster for running simulations in NEURON (Hines & Carnevale, 1997). NeuronPM provides a user-friendly way to use existing computing resources to catalog the performance of a neural simulation across a wide range of parameter values and experimental conditions. The NeuronPM client is a Windows-based screen saver, and the NeuronPM server can be hosted on any Apache/PHP/MySQL server. During idle time, the client retrieves model files and work assignments from the server, invokes NEURON to run the simulation, and returns results to the server. Administrative panels make it simple to upload model files, define the parameters and conditions to vary, and then monitor client status and work progress. NeuronPM is open-source freeware and is available for download at http://neuronpm.homeip.net . It is a useful entry-level tool for systematically analyzing complex neuron and network simulations.

  16. Designing a Digital Medical Management Training Simulator Using Distributed Cognition Theory

    OpenAIRE

    Rybing, Jonas; Prytz, Erik; Hornwall, Johan; Nilsson, Helene; Jonson, Carl-Oscar; Bång, Magnus

    2017-01-01

    Background Training of medical professionals is important to improve care during mass-causality events. Therefore, it is essential to extend knowledge on how to design valid and usable simulation-based training environments. Purpose This article investigates how distributed cognition and simulation theory concepts can guide design of simulation-based training environments. We present the design and user evaluation of DigEmergo, a simulator for training and assessing emergency medicine managem...

  17. Internet Based General Computer Simulation Platform for Distributed Multi-Robotic System

    Institute of Scientific and Technical Information of China (English)

    迟艳玲; 张斌; 王硕; 谭民

    2002-01-01

    A general computer simulation platform is designed for the purpose of catrrying out experiments on the Distributed Multi-Robotic System. The simulation platform is based on Internet and possesses generality, validity, real-time display and function of supporting algorithm developing. In addition, the platform is equipped wit recording and replay module, and simulation experiment can be reviewed at anytime.By now; a few algorithms have been developed on the Simulation Platform designed.

  18. Efficiently passing messages in distributed spiking neural network simulation.

    Science.gov (United States)

    Thibeault, Corey M; Minkovich, Kirill; O'Brien, Michael J; Harris, Frederick C; Srinivasa, Narayan

    2013-01-01

    Efficiently passing spiking messages in a neural model is an important aspect of high-performance simulation. As the scale of networks has increased so has the size of the computing systems required to simulate them. In addition, the information exchange of these resources has become more of an impediment to performance. In this paper we explore spike message passing using different mechanisms provided by the Message Passing Interface (MPI). A specific implementation, MVAPICH, designed for high-performance clusters with Infiniband hardware is employed. The focus is on providing information about these mechanisms for users of commodity high-performance spiking simulators. In addition, a novel hybrid method for spike exchange was implemented and benchmarked.

  19. Simulation of particle distribution in a room with air cleaner

    DEFF Research Database (Denmark)

    Ardkapan, Siamak Rahimi; Afshari, Alireza; Nielsen, Peter V.

    2012-01-01

    gas and particles with different sizes.The proper turbulence model was selected after comparing the results with the behaviour of the gass in the test room. The simulations showed the effect that the location of an air cleaner had on the particle level. The results showed that the location of the air...... and particle phase model for simulating an air cleaner in a room. In addition, the aim is to study the impact of location of an air cleaner in a room. The dynamics of the particle inside a room was simulated by computational fluid dynamics software. Furthermore, the air change rate was measured by both tracer...... cleaner in relation to inlet, outlet and particle source had a significant effect on the effectiveness of the air cleaner....

  20. Efficiently passing messages in distributed spiking neural network simulation

    Directory of Open Access Journals (Sweden)

    Corey Michael Thibeault

    2013-06-01

    Full Text Available Efficiently passing spiking messages in a neural model is an important aspect of high-performance simulation. As the scale of networks has increased so has the size of the computing systems required to simulate them. In addition, the information exchange of these resources has become more of an impediment to performance. In this paper we explore spike message passing using different mechanisms provided by the Message Passing Interface (MPI. A specific implementation, MVAPICH, designed for high-performance clusters with Infiniband hardware is employed. The focus is on providing information about these mechanisms for users of commodity high-performance spiking simulators. In addition, a novel hybrid-method for spike exchange was implemented and benchmarked.

  1. Etude et modélisation d'interactions complexes pour la simulation de foule

    OpenAIRE

    Bruneau, Julien

    2016-01-01

    This PhD has been focused on human interactions in complex situations whether by studyingsuch interactions or by proposing algorithms to simulate them. While also exploringhow to adapt an interaction to the current situation and target, in order to simulate awider range of situations, the focus has been on the combination of interactions. Analgorithm has been proposed to improve the way collision avoidance are combined whichimproved results in complex situations. Meanwhile, experiments have b...

  2. Molecular dynamics simulations of interactions between energetic dust and plasma-facing materials

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Guo-jian, E-mail: niugj@ipp.ac.cn [Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Li, Xiao-chun; Xu, Qian; Yang, Zhong-shi [Hefei Center Physical Science and Technology, Hefei (China); Luo, Guang-nan [Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Hefei Center Physical Science and Technology, Hefei (China); Hefei Science Center of CAS, Hefei (China)

    2015-11-15

    The interactions between dust and plasma-facing material (PFM) relate to the lifetime of PFM and impurity production. Series results have been obtained theoretically and experimentally but more detailed studies are needed. In present research, we investigate the evolution of kinetic, potential and total energy of plasma-facing material (PFM) in order to understand the dust/PFM interaction process. Three typical impacting energy are selected, i.e., 1, 10 and 100 keV/dust for low-, high- and hyper-energy impacting cases. For low impacting energy, dust particles stick on PFM surface without damaging it. Two typical time points exist and the temperature of PFM grows all the time but PFM structure experience a modifying process. Under high energy case, three typical points appear. The temperature curve fluctuates in the whole interaction process which indicates there are dust/PFM and kinetic/potential energy exchanges. In the hyper-energy case in present simulation, the violence dust/PFM interactions cause sputtering and crater investigating on energy evolution curves. We further propose the statistics of energy distribution. Results show that about half of impacting energy consumes on heating plasma-facing material meanwhile the other half on PFM structure deformation. Only a small proportion becomes kinetic energy of interstitial or sputtering atoms.

  3. Distribution function approach to irreversible adsorption of interacting colloidal particles

    Science.gov (United States)

    Faraudo, Jordi; Bafaluy, Javier

    2000-01-01

    A statistical-mechanical description of the irreversible adsorption of interacting colloidal particles is developed. Our approach describes in a consistent way the interaction of particles from the bulk with adsorbed particles during the transport process towards the adsorbing surface. The macroscopic physical quantities corresponding to the actual process are expressed as averages over simpler auxiliary processes which proceed in the presence of a fixed number n of adsorbed particles. The adsorption rate verifies a generalized Langmuir equation, in which the kinetic resistance (the inverse of the kinetic coefficient) is expressed as the sum of a diffusional resistance and a resistance due to interaction with adsorbed particles during the transport process (blocking effect). Contrary to previous approaches, the blocking effect is not due to geometrical exclusion, instead it measures how the transport from the bulk is affected by the adsorbed particles. From the general expressions obtained, we have derived coverage expansions for the adsorption rate and the surface correlation function. The theory is applied to the case of colloidal particles interacting through DLVO potentials. This form of the kinetic coefficient is shown to be in agreement with recent experimental results, in which RSA fails.

  4. Interactive Room Support for Complex and Distributed Design Projects

    DEFF Research Database (Denmark)

    Grønbæk, Kaj; Gundersen, Kristian Kroyer; Mogensen, Preben Holst

    2001-01-01

    We are investigating the design of digital 3D interaction technology embedded in a physical environment. We take as point of departure cemplex, collaborative industrial design projects involving heterogeneous sets of documents, and physical as well as digital 3D models. The paper introduces our n...

  5. GPGPU Approach: Simulation of the Interaction of Heavy Interstellar Atoms with the Heliosphere

    Science.gov (United States)

    DeStefano, A.

    2014-12-01

    Running simulations is an involved process taking many hours of computational time to complete. With the advent of cluster computing and parallel processing, problems may be solved in much less time compared to those run in serial. Specifically, NVIDIA released the parallel computing platform CUDA in 2007 giving researchers and programmers access to the GPU to solve generalized problems, and not those of just images.In current research, code has previously been developed to study the interaction of the heliosphere and heavy atoms from the local interstellar medium.Ionized species of hydrogen, helium and other heavy atoms are deflected by the heliosphere where as the neutral species are relatively unimpeded. Charge exchange of these neutral particles may occur between ionized species originating from the solar wind or other populations of pickup ions (PUI) modifying the shape and properties of the heliosphere, compared to one without neutrals. The details of the charge exchange interaction are element dependent and need to be investigated one by one. Current research has studied the interaction of local interstellar hydrogen with the heliosphere quite extensively with theory, simulations and modeling.Since hydrogen is the most abundant element care must be taken when coupling MHD equations with the charge exchange interactions. Simulation code has been developed to account for this dynamic problem and they have shown that the shape of the heliosphere is affected by this. Interstellar atoms heavier than hydrogen interacting with the heliosphere has been looked at as well, but not nearly with as much detail or sophisticated models as hydrogen. The heavy atom data collected by IBEX has in this sense been under-utilized by models.Previously, the simulation was computed with the use of MPI (Message Passing Interface) for parallelization. This approach provided a decrease in computational time. However, CUDA enables the programmer to take advantage of the computer

  6. Simplified Spatially-distributed Model for Inundation Simulations

    Science.gov (United States)

    Hsu, M. H.; Huang, C. J.; Su, Y. H.; Chen, A. S.

    2009-04-01

    Although traditional inundation models have been applied with good accuracy in Taiwan, they usually require a long computing time for simulations. However, the meteorological and geographical conditions in Taiwan frequently cause inundation within a short time period when storm occurs. The lead-time for emergency response in too short to indicate the areas with high flood risks for evacuation by using the traditional inundation models. The study established an inundation model for Taiwan and integrated the QPESUMS system which constructed and developed by the Central Weather Bureau. The radar precipitations by the QPESUMS system, as well as the rain-gauge records, are considered in the inundation model for real-time simulations. The precipitation data of typhoon NARI were simulated and evaluated different scale of grid size that the accuracy and efficiency of model would be suggested for practical applications. The Keelung River basin is adopted as the study areas of the inundation model. By use of QPESUMS radar precipitation for the typhoon HAITANG and KROSA, the inundation simulations can be calculated in a short time. The model will be executed in the future, to simulate the flood scenarios induced by the occurring and the forecasted rainfalls. The inundation will be predicted in 1-3 hours ahead to help the emergency managers taking proper strategies for disaster mitigations. Traditional inundation models have been widely applied with good accuracy to many studies in Taiwan. The main drawback of these models is that extraordinary requirement of computing time, which causes the obstacle for real-time applications. The meteorological and geographical conditions in Taiwan frequently result in flashfloods within short time periods when storms occur. The lead time for emergency response is too short to indicate the areas with high flood risks by using the traditional inundation models.

  7. Multi-scale interactions of geological processes during mineralization: cascade dynamics model and multifractal simulation

    Directory of Open Access Journals (Sweden)

    L. Yao

    2011-03-01

    Full Text Available Relations between mineralization and certain geological processes are established mostly by geologist's knowledge of field observations. However, these relations are descriptive and a quantitative model of how certain geological processes strengthen or hinder mineralization is not clear, that is to say, the mechanism of the interactions between mineralization and the geological framework has not been thoroughly studied. The dynamics behind these interactions are key in the understanding of fractal or multifractal formations caused by mineralization, among which singularities arise due to anomalous concentration of metals in narrow space. From a statistical point of view, we think that cascade dynamics play an important role in mineralization and studying them can reveal the nature of the various interactions throughout the process. We have constructed a multiplicative cascade model to simulate these dynamics. The probabilities of mineral deposit occurrences are used to represent direct results of mineralization. Multifractal simulation of probabilities of mineral potential based on our model is exemplified by a case study dealing with hydrothermal gold deposits in southern Nova Scotia, Canada. The extent of the impacts of certain geological processes on gold mineralization is related to the scale of the cascade process, especially to the maximum cascade division number nmax. Our research helps to understand how the singularity occurs during mineralization, which remains unanswered up to now, and the simulation may provide a more accurate distribution of mineral deposit occurrences that can be used to improve the results of the weights of evidence model in mapping mineral potential.

  8. Simulation of the interaction between Alfven waves and fast particles

    Energy Technology Data Exchange (ETDEWEB)

    Feher, Tamas Bela

    2014-02-18

    There is a wide variety of Alfven waves in tokamak and stellarator plasmas. While most of them are damped, some of the global eigenmodes can be driven unstable when they interact with energetic particles. By coupling the MHD code CKA with the gyrokinetic code EUTERPE, a hybrid kinetic-MHD model is created to describe this wave-particle interaction in stellarator geometry. In this thesis, the CKA-EUTERPE code package is presented. This numerical tool can be used for linear perturbative stability analysis of Alfven waves in the presence of energetic particles. The equations for the hybrid model are based on the gyrokinetic equations. The fast particles are described with linearized gyrokinetic equations. The reduced MHD equations are derived by taking velocity moments of the gyrokinetic equations. An equation for describing the Alfven waves is derived by combining the reduced MHD equations. The Alfven wave equation can retain kinetic corrections. Considering the energy transfer between the particles and the waves, the stability of the waves can be calculated. Numerically, the Alfven waves are calculated using the CKA code. The equations are solved as an eigenvalue problem to determine the frequency spectrum and the mode structure of the waves. The results of the MHD model are in good agreement with other sophisticated MHD codes. CKA results are shown for a JET and a W7-AS example. The linear version of the EUTERPE code is used to study the motion of energetic particles in the wavefield with fixed spatial structure, and harmonic oscillations in time. In EUTERPE, the gyrokinetic equations are discretized with a PIC scheme using the delta-f method, and both full orbit width and finite Larmor radius effects are included. The code is modified to be able to use the wavefield calculated externally by CKA. Different slowing-down distribution functions are also implemented. The work done by the electric field on the particles is measured to calculate the energy transfer

  9. Simulation model of load balancing in distributed computing systems

    Science.gov (United States)

    Botygin, I. A.; Popov, V. N.; Frolov, S. G.

    2017-02-01

    The availability of high-performance computing, high speed data transfer over the network and widespread of software for the design and pre-production in mechanical engineering have led to the fact that at the present time the large industrial enterprises and small engineering companies implement complex computer systems for efficient solutions of production and management tasks. Such computer systems are generally built on the basis of distributed heterogeneous computer systems. The analytical problems solved by such systems are the key models of research, but the system-wide problems of efficient distribution (balancing) of the computational load and accommodation input, intermediate and output databases are no less important. The main tasks of this balancing system are load and condition monitoring of compute nodes, and the selection of a node for transition of the user’s request in accordance with a predetermined algorithm. The load balancing is one of the most used methods of increasing productivity of distributed computing systems through the optimal allocation of tasks between the computer system nodes. Therefore, the development of methods and algorithms for computing optimal scheduling in a distributed system, dynamically changing its infrastructure, is an important task.

  10. Research and Implementation of Distributed Virtual Simulation Platform Based on Components

    Institute of Scientific and Technical Information of China (English)

    SUN Zhi-xin; WANG Ru-chuan; WANG Shao-di

    2004-01-01

    This paper proposes a combination of system's theoretic simulation methodology with the virtual reality technology as a basis for a component-based virtual simulation framework. The created universal framework can be used in different fields, such as drive training, airplane fighting training, and so on. The result of the synergism is a powerful component-based virtual simulation framework. After having briefly introduced the concepts and principles of the distributed component object, the paper describes a software development method based on components. Then a method of virtual simulation system modeling based on components is proposed, and the integrated framework supporting distributed virtual simulation and its key technologies are discussed at length. Our experiments indicate that the framework can be widely used in simulation fields such as arms antagonism, driving simulation and so on.

  11. DIGI-vis: Distributed interactive geospatial information visualization

    KAUST Repository

    Ponto, Kevin

    2010-03-01

    Geospatial information systems provide an abundance of information for researchers and scientists. Unfortunately this type of data can usually only be analyzed a few megapixels at a time, giving researchers a very narrow view into these voluminous data sets. We propose a distributed data gathering and visualization system that allows researchers to view these data at hundreds of megapixels simultaneously. This system allows scientists to view real-time geospatial information at unprecedented levels expediting analysis, interrogation, and discovery. ©2010 IEEE.

  12. T-Algorithm-Based Logic Simulation on Distributed Systems

    OpenAIRE

    Sundaram, S; Patnaik, LM

    1992-01-01

    Increase in the complexity of VLSI digital circuit it sign demands faster logic simulation techniques than those currently available. One of the ways of speeding up existing logic simulataon algorithms is by exploiting the inherent parallelism an the sequentaal versaon. In this paper, we explore the possibility of mapping a T-algoriihm based logac samulataon algorithm onto a cluster of workstation interconnected by an ethernet. The set of gates at a particular level as partitioned by the hias...

  13. Aggregated Representation of Distribution Networks for Large-Scale Transmission Network Simulations

    DEFF Research Database (Denmark)

    Göksu, Ömer; Altin, Müfit; Sørensen, Poul Ejnar

    2014-01-01

    As a common practice of large-scale transmission network analysis the distribution networks have been represented as aggregated loads. However, with increasing share of distributed generation, especially wind and solar power, in the distribution networks, it became necessary to include...... the distributed generation within those analysis. In this paper a practical methodology to obtain aggregated behaviour of the distributed generation is proposed. The methodology, which is based on the use of the IEC standard wind turbine models, is applied on a benchmark distribution network via simulations....

  14. Study on visualization simulation of temperature distributions in surrounding rock of tunnels in a deep mine

    Institute of Scientific and Technical Information of China (English)

    SUN Pei-de

    2006-01-01

    Based on the mathematical model for rock temperature distribution in a geothermal field, the properties of rock temperature distribution in geothermal field for four kinds of surrounding rock cross-sections of tunnels in a deep mine were simulated by using finite element method. It is shown that the relationship for rock temperature distribution varied with the geothermal parameters, time and space. Namely, 2-dimensional time-dependent isograms clearly showed the process for rock temperature variation and distribution in a geothermal field which has been redisplayed with visualization numerical simulation.

  15. A methodology for simulated experiments in interactive search

    OpenAIRE

    2010-01-01

    Interactive information retrieval has received much attention in recent years, e.g. [7]. Furthermore, increased activity in developing interactive features in search systems used across existing popular Web search engines suggests that interactive systems are being recognised as a promising next step in assisting information search. One of the most challenging problems with interactive systems however remains evaluation.\\ud \\ud We describe the general specifications of a methodology for condu...

  16. Simulating the Immune Response on a Distributed Parallel Computer

    Science.gov (United States)

    Castiglione, F.; Bernaschi, M.; Succi, S.

    The application of ideas and methods of statistical mechanics to problems of biological relevance is one of the most promising frontiers of theoretical and computational mathematical physics.1,2 Among others, the computer simulation of the immune system dynamics stands out as one of the prominent candidates for this type of investigations. In the recent years immunological research has been drawing increasing benefits from the resort to advanced mathematical modeling on modern computers.3,4 Among others, Cellular Automata (CA), i.e., fully discrete dynamical systems evolving according to boolean laws, appear to be extremely well suited to computer simulation of biological systems.5 A prominent example of immunological CA is represented by the Celada-Seiden automaton, that has proven capable of providing several new insights into the dynamics of the immune system response. To date, the Celada-Seiden automaton was not in a position to exploit the impressive advances of computer technology, and notably parallel processing, simply because no parallel version of this automaton had been developed yet. In this paper we fill this gap and describe a parallel version of the Celada-Seiden cellular automaton aimed at simulating the dynamic response of the immune system. Details on the parallel implementation as well as performance data on the IBM SP2 parallel platform are presented and commented on.

  17. Fully Coupled Fluid-Structure Interaction Model Based on Distributed Lagrange Multiplier/Fictitious Domain Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper, with a finite element method, studies the interaction of a coupled incompressible fluid-rigid structure system with a free surface subjected to external wave excitations. With this fully coupled model, the rigid structure is taken as "fictitious" fluid with zero strain rate. Both fluid and structure are described by velocity and pressure. The whole domain, including fluid region and structure region, is modeled by the incompressible Navier-Stokes equations which are discretized with fixed Eulerian mesh. However, to keep the structure's rigid body shape and behavior, a rigid body constraint is enforced on the "fictitious" fluid domain by use of the Distributed Lagrange Multiplier/Fictitious Domain (DLM/FD) method which is originally introduced to solve particulate flow problems by Glowinski et al. For the verification of the model presented herein, a 2D numerical wave tank is established to simulate small amplitude wave propagations, and then numerical results are compared with analytical solutions. Finally, a 2D example of fluid-structure interaction under wave dynamic forces provides convincing evidences for the method excellent solution quality and fidelity.

  18. All-atom Molecular Dynamic Simulations and NMR Spectra Study on Intermolecular Interactions of N,N-dimethylacetamide-Water System

    Institute of Scientific and Technical Information of China (English)

    Rong Zhang; Zai-you Tan; San-lai Luo

    2008-01-01

    N,N-dimethylacetamide (DMA) has been investigated extensively in studying models of peptide bonds. An all-atom MD simulation and the NMR spectra were performed to investigate the interactions in the DMA- water system. The radial distribution functions (RDFs) and the hydrogen-bonding network were used in MD simulations. There are strong hydrogen bonds and weak C-H…O contacts in the mixtures, as shown by the analysis of the RDFs. The insight structures in the DMA-water mixtures can be classified into different regions by the analysis of the hydrogen-bonding network. Chemical shifts of the hydrogen atom of water molecule with concentration and temperatures are adopted to study the interactions in the mixtures. The results of NMR spectra show good agreement with the statistical results of hydrogen bonds in MD simulations.

  19. Building interactive virtual environments for simulated training in medicine using VRML and Java/JavaScript.

    Science.gov (United States)

    Korocsec, D; Holobar, A; Divjak, M; Zazula, D

    2005-12-01

    Medicine is a difficult thing to learn. Experimenting with real patients should not be the only option; simulation deserves a special attention here. Virtual Reality Modelling Language (VRML) as a tool for building virtual objects and scenes has a good record of educational applications in medicine, especially for static and animated visualisations of body parts and organs. However, to create computer simulations resembling situations in real environments the required level of interactivity and dynamics is difficult to achieve. In the present paper we describe some approaches and techniques which we used to push the limits of the current VRML technology further toward dynamic 3D representation of virtual environments (VEs). Our demonstration is based on the implementation of a virtual baby model, whose vital signs can be controlled from an external Java application. The main contributions of this work are: (a) outline and evaluation of the three-level VRML/Java implementation of the dynamic virtual environment, (b) proposal for a modified VRML Timesensor node, which greatly improves the overall control of system performance, and (c) architecture of the prototype distributed virtual environment for training in neonatal resuscitation comprising the interactive virtual newborn, active bedside monitor for vital signs and full 3D representation of the surgery room.

  20. Research framework of integrated simulation on bilateral interaction between water cycle and socio-economic development

    Science.gov (United States)

    Hao, C. F.; Yang, X. L.; Niu, C. W.; Jia, Y. W.

    2016-08-01

    The mechanism of bilateral interaction between natural water cycle evolution and socio-economic development has been obscured in current research due to the complexity of the hydrological process and the socio-economic system. The coupling of economic model CGE (Computable General Equilibrium) and distributed hydrological model WEP (Water and Energy transfer Processes) provides a model-based tool for research on response and feedback of water cycle and social development, as well as economic prospects under the constraint of water resources. On one hand, water policies, such as water use limitation and water price adjustment under different levels of socio-economic development, are to be evaluated by CGE model as assumed conditions and corresponding results of water demand could be put into WEP model to simulate corresponding response during the whole process of water cycle. On the other hand, variation of available water resources quantity under different scenarios simulated by WEP model may provide proper limitation for water demand in CGE model, and corresponding change of economic factors could indicate the influence of water resources constraints on socio-economic development. The research is believed to be helpful for better understanding of bilateral interaction between water and society.

  1. Engaging Undergraduate Math Majors in Geoscience Research using Interactive Simulations and Computer Art

    Science.gov (United States)

    Matott, L. S.; Hymiak, B.; Reslink, C. F.; Baxter, C.; Aziz, S.

    2012-12-01

    As part of the NSF-sponsored 'URGE (Undergraduate Research Group Experiences) to Compute' program, Dr. Matott has been collaborating with talented Math majors to explore the design of cost-effective systems to safeguard groundwater supplies from contaminated sites. Such activity is aided by a combination of groundwater modeling, simulation-based optimization, and high-performance computing - disciplines largely unfamiliar to the students at the outset of the program. To help train and engage the students, a number of interactive and graphical software packages were utilized. Examples include: (1) a tutorial for exploring the behavior of evolutionary algorithms and other heuristic optimizers commonly used in simulation-based optimization; (2) an interactive groundwater modeling package for exploring alternative pump-and-treat containment scenarios at a contaminated site in Billings, Montana; (3) the R software package for visualizing various concepts related to subsurface hydrology; and (4) a job visualization tool for exploring the behavior of numerical experiments run on a large distributed computing cluster. Further engagement and excitement in the program was fostered by entering (and winning) a computer art competition run by the Coalition for Academic Scientific Computation (CASC). The winning submission visualizes an exhaustively mapped optimization cost surface and dramatically illustrates the phenomena of artificial minima - valley locations that correspond to designs whose costs are only partially optimal.

  2. Distributional approach to point interactions in one-dimensional quantum mechanics

    Directory of Open Access Journals (Sweden)

    Marcos eCalçada

    2014-04-01

    Full Text Available We consider the one-dimensional quantum mechanical problem of defining interactions concentrated at a single point in the framework of the theory of distributions. The often ill-defined product which describes the interaction term in the Schrodinger and Dirac equations is replaced by a well-defined distribution satisfying some simple mathematical conditions and, in addition, the physical requirement of probability current conservation is imposed. A four-parameter family of interactions thus emerges as the most general point interaction both in the non-relativistic and in the relativistic theories (in agreement with results obtained by self-adjoint extensions. Since the interaction is given explicitly, the distributional method allows one to carry out symmetry investigations in a simple way, and it proves to be useful to clarify some ambiguities related to the so-called $delta^prime$ interaction.

  3. Need for Agility in Security Constraints for Distributed Simulation

    Science.gov (United States)

    2014-06-01

    Army locations, Fort Sill and Fort Bliss, are accessed through the JTEN network shown in Figure 1. By using a distributed architecture geographically...a tiered approach and establish separate guards with their own rule bases for each tier of international partners. For example, the English speaking ...time to speak with us and share their experiences and information. Without their assistance this paper would not have been possible. 19_ICCRTS

  4. Simulation of Velocity and Temperature Distributions of Displacement Ventilation System with Single or Double Heat Sources

    Institute of Scientific and Technical Information of China (English)

    Wenfei Wu; Xuan Wu; Yanhui Feng; Xinxin Zhang

    2007-01-01

    In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verified by experiments, based on this, the velocity and temperature distribution of three-dimensional displacement ventilation system with single and double heat sources are studied. Velocity and temperature fields under two different cases of heat source are analyzed and compared. The numerical results show that there are three layers in vertical temperature fields of displacement ventilation system with single or double heat sources, and the vertical temperature distribution of single heat source is different from that of double heat sources. When indoor load is large, the comfort requirement of people indoor can't be satisfied with displacement ventilation system only, thus an additional refrigeration system is necessary. Furthermore, under the condition of two heat sources, the displacement ventilation parameters can't be computed simply according to single heat source inlet parameters, therefore the interaction between heat sources should be considered.

  5. Crisscross Optimization Algorithm and Monte Carlo Simulation for Solving Optimal Distributed Generation Allocation Problem

    Directory of Open Access Journals (Sweden)

    Xiangang Peng

    2015-12-01

    Full Text Available Distributed generation (DG systems are integral parts in future distribution networks. In this paper, a novel approach integrating crisscross optimization algorithm and Monte Carlo simulation (CSO-MCS is implemented to solve the optimal DG allocation (ODGA problem. The feature of applying CSO to address the ODGA problem lies in three interacting operators, namely horizontal crossover, vertical crossover and competitive operator. The horizontal crossover can search new solutions in a hypercube space with a larger probability while in the periphery of each hypercube with a decreasing probability. The vertical crossover can effectively facilitate those stagnant dimensions of a population to escape from premature convergence. The competitive operator allows the crisscross search to always maintain in a historical best position to quicken the converge rate. It is the combination of the double search strategies and competitive mechanism that enables CSO significant advantage in convergence speed and accuracy. Moreover, to deal with system uncertainties such as the output power of wind turbine and photovoltaic generators, an MCS-based method is adopted to solve the probabilistic power flow. The effectiveness of the CSO-MCS method is validated on the typical 33-bus and 69-bus test system, and results substantiate the suitability of CSO-MCS for multi-objective ODGA problem.

  6. Matrix-fracture interactions in dual porosity simulation

    Energy Technology Data Exchange (ETDEWEB)

    Shook, G.M.

    1996-01-01

    A new method for simulating flow in fractured media is presented which uses a truncated version of the analytical solution to resolve pressure transients in the rock matrix. The point at which the series solution may be truncated is a known function of the problem, and may therefore be readily determined. Furthermore, the functional form of the method is essentially dimension-independent, and implementation of the method requires only minimal modification to an existing dual porosity simulator. Three test cases are presented comparing results from fine grid simulations, Warren and Root simulations, and the new formulation. In each of the three cases presented, excellent agreement with the fine grid simulations is obtained using the new method. The W&R formulation exhibits excessive error throughout the simulated time, first underpredicting outflow rates, and then overpredicting rates. The error using the W&R formulation is largest for 3-D fracture networks, but is large for all cases tested.

  7. Role of subgrid-scale modeling in large eddy simulation of wind turbine wake interactions

    DEFF Research Database (Denmark)

    Sarlak, Hamid; Meneveau, C.; Sørensen, Jens Nørkær

    2015-01-01

    A series of simulations are carried out to evaluate specific features of the Large Eddy Simulation (LES) technique in wind turbine wake interactions. We aim to model wake interactions of two aligned model rotors. The effects of the rotor resolution, actuator line force filter size, and Reynolds...

  8. Simulating the hydrologic cycle in coal mining subsidence areas with a distributed hydrologic model

    Science.gov (United States)

    Wang, Jianhua; Lu, Chuiyu; Sun, Qingyan; Xiao, Weihua; Cao, Guoliang; Li, Hui; Yan, Lingjia; Zhang, Bo

    2017-01-01

    Large-scale ground subsidence caused by coal mining and subsequent water-filling leads to serious environmental problems and economic losses, especially in plains with a high phreatic water level. Clarifying the hydrologic cycle in subsidence areas has important practical value for environmental remediation, and provides a scientific basis for water resource development and utilisation of the subsidence areas. Here we present a simulation approach to describe interactions between subsidence area water (SW) and several hydrologic factors from the River-Subsidence-Groundwater Model (RSGM), which is developed based on the distributed hydrologic model. Analysis of water balance shows that the recharge of SW from groundwater only accounts for a small fraction of the total water source, due to weak groundwater flow in the plain. The interaction between SW and groundwater has an obvious annual cycle. The SW basically performs as a net source of groundwater in the wet season, and a net sink for groundwater in the dry season. The results show there is an average 905.34 million m3 per year of water available through the Huainan coal mining subsidence areas (HCMSs). If these subsidence areas can be integrated into water resource planning, the increasingly precarious water supply infrastructure will be strengthened. PMID:28106048

  9. Simulating the hydrologic cycle in coal mining subsidence areas with a distributed hydrologic model

    Science.gov (United States)

    Wang, Jianhua; Lu, Chuiyu; Sun, Qingyan; Xiao, Weihua; Cao, Guoliang; Li, Hui; Yan, Lingjia; Zhang, Bo

    2017-01-01

    Large-scale ground subsidence caused by coal mining and subsequent water-filling leads to serious environmental problems and economic losses, especially in plains with a high phreatic water level. Clarifying the hydrologic cycle in subsidence areas has important practical value for environmental remediation, and provides a scientific basis for water resource development and utilisation of the subsidence areas. Here we present a simulation approach to describe interactions between subsidence area water (SW) and several hydrologic factors from the River-Subsidence-Groundwater Model (RSGM), which is developed based on the distributed hydrologic model. Analysis of water balance shows that the recharge of SW from groundwater only accounts for a small fraction of the total water source, due to weak groundwater flow in the plain. The interaction between SW and groundwater has an obvious annual cycle. The SW basically performs as a net source of groundwater in the wet season, and a net sink for groundwater in the dry season. The results show there is an average 905.34 million m3 per year of water available through the Huainan coal mining subsidence areas (HCMSs). If these subsidence areas can be integrated into water resource planning, the increasingly precarious water supply infrastructure will be strengthened.

  10. Simulation models developed for voltage control in a distribution network using energy storage systems for PV penetration

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Bindner, Henrik W.

    2013-01-01

    This paper presents the development of simulation models for DER components in a distribution network, with focus on voltage controllers using energy storage systems for PV penetration. The Vanadium Redox Battery (VRB) system model, used as an energy storage system, was implemented in MATLAB....../Simulink and DIgSILENT PowerFactory, based on the efficiency of different components-such as: cell stacks, electrolytes, pumps and power converters, whilst power losses were also taken into account. The simulation results have been validated against measurements using experimental facility of a distributed power...... system laboratory. To study the variability and the interaction between feeders including VRB, PV system and active units an overvoltage controller has also been developed, implemented and tested successfully....

  11. Simulation of fog influence on laser beam distribution in atmosphere

    Science.gov (United States)

    Vasinek, Vladimir; Latal, Jan; Koudelka, Petr; Vitasek, Jan; Witas, Karel; Hejduk, Stanislav

    2012-10-01

    Optical fibreless data networks P2P offer fast data transmissions with big transmittance from 1- 10 Gbps on a distance of 1- 6 km. Perfections of such networks are especially flexibility, rapid creation of communications. Sensitivity to atmospheric influences, necessity of light on sight belongs to disadvantages. Transmission through atmosphere be characterized by non-stationarity, inhomogeneity, the influences have random character. It means immediately that it is possible only with difficulty to project conclusions concerning to the measurement on one line upon fiberless line in another position. Contribution tackles a question of forming of the artificial hazy atmospheres, finding the statistical parameters of artificially created foggy atmospheres that could be reproduced to real environment. This work describes created laboratory apparatus powered with fog generator, heat source and ventilating fans, which allow in a controlled way to change the optical transmission inside the bounded space. Laser diode radiation at wavelength of 850 nm is transmitted into created space like this which is scanned with optical power meter after passing of artificially created turbulent vaporous environment. Changes in intensity of the passed lights are captured; the mean value and maximum deviation from the mean value are computed. In this way it is possible to change the reached specific attenuation in dB/km. Owing to turbulences it happens to deviations from the mean value, these abnormalities are characterized by the distribution function that describes the size of turbulences in time. By the help of ergodic theorem then it is possible to deduce that the distribution function of the foggy turbulences gained at continuous time evaluation has same history like the distribution function gained behind the same conditions in the setup in other times. It holds as well that these distribution functions are the same for variety of points in experimental space, provided there are

  12. A DLM/FD/IB Method for Simulating Cell/Cell and Cell/Particle Interaction in Microchannels

    Institute of Scientific and Technical Information of China (English)

    Tsorng-Whay PAN; Lingling SHI; Roland GLOWINSKI

    2010-01-01

    A spring model is used to simulate the skeleton structure of the red blood cell(RBC)membrane and to study the red blood cell(RBC)rheology in Poiseuille flow with an immersed boundary method.The lateral migration properties of many cells in Poiseuille flow have been investigated.The authors also combine the above methodology with a distributed Lagrange multiplier/fictitious domain method to simulate the interaction of cells and neutrally buoyant particles in a microchannel for studying the margination of particles.

  13. Interactive verification of Markov chains: Two distributed protocol case studies

    Directory of Open Access Journals (Sweden)

    Johannes Hölzl

    2012-12-01

    Full Text Available Probabilistic model checkers like PRISM only check probabilistic systems of a fixed size. To guarantee the desired properties for an arbitrary size, mathematical analysis is necessary. We show for two case studies how this can be done in the interactive proof assistant Isabelle/HOL. The first case study is a detailed description of how we verified properties of the ZeroConf protocol, a decentral address allocation protocol. The second case study shows the more involved verification of anonymity properties of the Crowds protocol, an anonymizing protocol.

  14. Distributed Parallel Interactive Data Analysis Using the Proof System

    Institute of Scientific and Technical Information of China (English)

    ReneBrun; FonsRademakers

    2001-01-01

    The only way Terabytes of data can be processed and analyzed in a reasonable time is by using parallel processing architectures.The Paralle ROOT Facility,PROOF,is s system for the parallel interactive analysis of such datasets on clusters of heterogeneous computers.Early prototypes have confirmed the validity of the basic PROOF architecture However,some important work still has to be done before PROOF can be used as a production facility.The basic architecture and the planned developments are described in this paper.

  15. SLA-Driven Simulation of Multi-Tenant Scalable Cloud-Distributed Enterprise Information Systems

    OpenAIRE

    2014-01-01

    Cloud Computing is an enabler for delivering large-scale, distributed enterprise applications with strict requirements in terms of performance. It is often the case that such applications have complex scaling and Service Level Agreement (SLA) management requirements. In this paper we present a simulation approach for validating and comparing SLA-aware scaling policies using the CloudSim simulator, using data from an actual Distributed Enterprise Information System (dEIS). We extend CloudSim w...

  16. Statistics of interacting networks with extreme preferred degrees: Simulation results and theoretical approaches

    Science.gov (United States)

    Liu, Wenjia; Schmittmann, Beate; Zia, R. K. P.

    2012-02-01

    Network studies have played a central role for understanding many systems in nature - e.g., physical, biological, and social. So far, much of the focus has been the statistics of networks in isolation. Yet, many networks in the world are coupled to each other. Recently, we considered this issue, in the context of two interacting social networks. In particular, We studied networks with two different preferred degrees, modeling, say, introverts vs. extroverts, with a variety of ``rules for engagement.'' As a first step towards an analytically accessible theory, we restrict our attention to an ``extreme scenario'': The introverts prefer zero contacts while the extroverts like to befriend everyone in the society. In this ``maximally frustrated'' system, the degree distributions, as well as the statistics of cross-links (between the two groups), can depend sensitively on how a node (individual) creates/breaks its connections. The simulation results can be reasonably well understood in terms of an approximate theory.

  17. Compressive characteristics of single walled carbon nanotube with water interactions investigated by using molecular dynamics simulation

    Science.gov (United States)

    Wong, C. H.; Vijayaraghavan, V.

    2014-01-01

    The elastic properties of single walled carbon nanotube (SWCNT) with surrounding water interactions are studied using molecular dynamics simulation technique. The compressive loading characteristic of carbon nanotubes (CNTs) in a fluidic medium such as water is critical for its role in determining the lifetime and stability of CNT based nano-fluidic devices. In this paper, we conducted a comprehensive analysis on the effect of geometry, chirality and density of encapsulated water on the elastic properties of SWCNT. Our studies show that defect density and distribution can strongly impact the compressive resistance of SWCNTs in water. Further studies were conducted on capped SWCNTs with varying densities of encapsulated water, which is necessary to understand the strength of CNT as a potential drug carrier. The results obtained from this paper will help determining the potential applications of CNTs in the field of nano-electromechanical systems (NEMS) such as nano-biological and nano-fluidic devices.

  18. Compressive characteristics of single walled carbon nanotube with water interactions investigated by using molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Wong, C.H., E-mail: chwong@ntu.edu.sg; Vijayaraghavan, V.

    2014-01-24

    The elastic properties of single walled carbon nanotube (SWCNT) with surrounding water interactions are studied using molecular dynamics simulation technique. The compressive loading characteristic of carbon nanotubes (CNTs) in a fluidic medium such as water is critical for its role in determining the lifetime and stability of CNT based nano-fluidic devices. In this paper, we conducted a comprehensive analysis on the effect of geometry, chirality and density of encapsulated water on the elastic properties of SWCNT. Our studies show that defect density and distribution can strongly impact the compressive resistance of SWCNTs in water. Further studies were conducted on capped SWCNTs with varying densities of encapsulated water, which is necessary to understand the strength of CNT as a potential drug carrier. The results obtained from this paper will help determining the potential applications of CNTs in the field of nano-electromechanical systems (NEMS) such as nano-biological and nano-fluidic devices.

  19. Simulations of ice jam thickness distribution in the transverse direction

    Institute of Scientific and Technical Information of China (English)

    王军; 施发义; 陈胖胖

    2014-01-01

    River ice often forms in the cold regions of northern hemisphere which can lead to ice jams (or ice dams). Water level can be significantly raised due to ice jams. As a consequence, disastrous ice flooding may be resulted, such as the ice jam flooding in the Nechako River in Prince George in winter 2007-2008. In the present study, the equations describing the ice jam thickness in the transverse direction are derived. The impact of the secondary vortex is considered while the cohesive force within ice cubes is neglected in the model. The relationship between the parameterb and the total water depth is established based on the assumption that all other variables except the velocities are kept constant on the same cross section. By using the parameterb and the developed equations, the ice jam thickness in the transverse direction can be predicted. The developed model is used to simulate the ice jam thickness in the transverse direction at the Hequ Reach of the Yellow River in China. The simulated ice jam thicknesses agree well with the field measurements on different cross sections.

  20. Simulation of hydrodynamically interacting particles confined by a spherical cavity

    Science.gov (United States)

    Aponte-Rivera, Christian; Zia, Roseanna N.

    2016-06-01

    We present a theoretical framework to model the behavior of a concentrated colloidal dispersion confined inside a spherical cavity. Prior attempts to model such behavior were limited to a single enclosed particle and attempts to enlarge such models to two or more particles have seen limited success owing to the challenges of accurately modeling many-body and singular hydrodynamic interactions. To overcome these difficulties, we have developed a set of hydrodynamic mobility functions that couple particle motion with hydrodynamic traction moments that, when inverted and combined with near-field resistance functions, form a complete coupling tensor that accurately captures both the far-field and near-field physics and is valid for an arbitrary number of spherical particles enclosed by a spherical cavity of arbitrary relative size a /R , where a and R are the particle and cavity size, respectively. This framework is then utilized to study the effect of spherical confinement on the self- and entrained motion of the colloids, for a range of particle-to-cavity size ratios. The self-motion of a finite-size enclosed particle is studied first, recovering prior results published in the literature: The hydrodynamic mobility of the particle is greatest at the center of the cavity and decays as (a /R ) /(1 -y2) , where y is the particle distance to the cavity center. Near the cavity wall, the no-slip surfaces couple strongly and mobility along the cavity radius vanishes as ξ ≡R -(a +y ) , where y is center-to-center distance from particle to cavity. Corresponding motion transverse to the cavity radius vanishes as [ln(1/ξ ) ] -1. The effect of confinement on entrainment of a particle in the flow created by the motion of others is also studied, where we find that confinement exerts a qualitative effect on the strength and anisotropy of entrainment of a passive particle dragged by the flow of a forced particle. As expected, entrainment strength decays with increased distance

  1. Room Acoustical Simulation Algorithm Based on the Free Path Distribution

    Science.gov (United States)

    VORLÄNDER, M.

    2000-04-01

    A new algorithm is presented which provides estimates of impulse responses in rooms. It is applicable to arbitrary shaped rooms, thus including non-diffuse spaces like workrooms or offices. In the latter cases, for instance, sound propagation curves are of interest to be applied in noise control. In the case of concert halls and opera houses, the method enables very fast predictions of room acoustical criteria like reverberation time, strength or clarity. The method is based on a low-resolved ray tracing and recording of the free paths. Estimates of impulse responses are derived from evaluation of the free path distribution and of the free path transition probabilities.

  2. Good experiences with interactive temporal bone surgical simulator

    DEFF Research Database (Denmark)

    Andersen, Steven A W; Mikkelsen, Peter Trier; Noe, Karsten Ostergaard;

    2014-01-01

    The Visible Ear Simulator (VES) is a freeware temporal bone surgical simulator utilizing a high-fidelity haptic and graphical voxel model compiled from segmented digital images of fresh frozen sections. A haptic device provides the 3-dimensional handling and drilling with force-feedback in real...

  3. An Interactive Teaching System for Bond Graph Modeling and Simulation in Bioengineering

    Science.gov (United States)

    Roman, Monica; Popescu, Dorin; Selisteanu, Dan

    2013-01-01

    The objective of the present work was to implement a teaching system useful in modeling and simulation of biotechnological processes. The interactive system is based on applications developed using 20-sim modeling and simulation software environment. A procedure for the simulation of bioprocesses modeled by bond graphs is proposed and simulators…

  4. LARGE EDDY SIMULATION OF THE INTERACTION BETWEEN WALL JET AND OFFSET JET

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-wei; HUAI Wen-xin; HAN Jie

    2011-01-01

    The interaction between a plane wall jet and a parallel offset jet is studied through the Large Eddy Simulation (LES).In order to compare with the related experimental data,the offset ratio is set to be 1.0 and the Reynolds number Re is 1.0×104 with respect to the jet height L and the exit velocity U0.The Finite Volume Method (FVM) with orthogonal-mesh (6.17±106 nodes) is used to discretize governing equations.The large eddies are obtained directly,while the small eddies are simulated by using the Dynamic Smagorinsky-Lily Model (DSLM) and the Dynamic Kinetic energy Subgrid-scale Model (DKSM).Comparisons between computational results and experimental data show that the DKSM is especially effective in predicting the mean stream-wise velocity,the half-width of the velocity and the decay of the maximum velocity.The variations of the mean stream-wise velocity and the turbulent intensity at several positions are also obtained,and their distributions agree well with the measurements.The further analysis of dilute characteristics focuses on the tracer concentration,such as the distributions of the concentration (i.e.,C / C0 or C/Cm ),the boundary layer thickness δc and the half-width of the concentration bc,the decay of the maximum concentration ( Cm / Co) along the downstream direction.The turbulence mechanism is also analyzed in some aspects,such as the coherent structure,the correlation function and the Probability Density Function (PDF) of the fluctuating velocity.The results show that the interaction between the two jets is strong near the jet exit and they are fully merged after a certain distance.

  5. Cognitive load in distributed and massed practice in virtual reality mastoidectomy simulation

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars;

    2016-01-01

    -integrated tutoring on CL in virtual reality (VR) mastoidectomy simulation. STUDY DESIGN: Prospective trial. METHODS: Forty novice medical students performed 12 repeated virtual mastoidectomy procedures in the Visible Ear Simulator: 21 completed distributed practice with practice blocks spaced in time and 19...

  6. Mathematical simulation application for research of nonuniform distributed-parameter circuit transients

    Science.gov (United States)

    Kuleshova, E. O.; Plyusnin, A. A.; Shandarova, E. B.; Tikhomirova, O. V.

    2016-04-01

    This paper considers the simulation capability of nonuniform distributed-parameter circuit transients by using MatLab Simulink. This approach is capable of determining currents and voltages of nodes for power networks of any configurations and modes. The paper contains results of nonuniform line simulations in idle, short-circuit and load modes.

  7. Wetlands Spatial-Temporal Distribution Multi-Scale Simulation Using Multi-Agent System

    Directory of Open Access Journals (Sweden)

    Huan Yu

    2012-08-01

    Full Text Available The simulation of wetland landscape spatial-temporal distribution not only can reveal the mechanisms and laws of landscape evolution, but achieve the sustainable land use as well as provide supports for wetland conservation and management. In this report, the inland freshwater wetlands in the Sanjiang Plain of China were selected for wetland landscape changing process simulation studies. Results showed that both visual effects of simulation and prediction were good and the total accuracy co-efficiency of points to points was also significantly high (above 82%, which demonstrated the feasibility and effectiveness of wetland landscape spatial-temporal distribution simulation using Multi-Agent System (MAS. Scales exerted influence on visual effects, simulation accuracies and statistics of landscape index. Scale effects were obvious during simulation process using MAS. It was demonstrated that 60m was the best scale for simulation. It was shown that contagion index lines were exponential distribution while accuracy lines were lognormal distribution with the scale rising, which provided a reference for scale effect assessment and simulation scale selection.

  8. Computer simulation of the effects of a distributed array antenna on synthetic aperture radar images

    Science.gov (United States)

    Estes, J. M.

    1985-01-01

    The ARL:UT orbital SAR simulation has been upgraded to use three-dimensional antenna gain patterns. This report describes the modifications and presents quantitative image analyses of a simulation using antenna patterns generated from the modeling of a distributed array antenna.

  9. Integrating international relations and environmental science course concepts through an interactive world politics simulation

    Science.gov (United States)

    Straub, K. H.; Kesgin, B.

    2012-12-01

    During the fall 2012 semester, students in two introductory courses at Susquehanna University - EENV:101 Environmental Science and POLI:131 World Affairs - will participate together in an online international relations simulation called Statecraft (www.statecraftsim.com). In this strategy game, students are divided into teams representing independent countries, and choose their government type (democracy, constitutional monarchy, communist totalitarian, or military dictatorship) and two country attributes (industrial, green, militaristic, pacifist, or scientific), which determine a set of rules by which that country must abide. Countries interact over issues such as resource distribution, war, pollution, immigration, and global climate change, and must also keep domestic political unrest to a minimum in order to succeed in the game. This simulation has typically been run in political science courses, as the goal is to allow students to experience the balancing act necessary to maintain control of global and domestic issues in a dynamic, diverse world. This semester, environmental science students will be integrated into the simulation, both as environmental advisers to each country and as independent actors representing groups such as Greenpeace, ExxonMobil, and UNEP. The goal in integrating the two courses in the simulation is for the students in each course to gain both 1) content knowledge of certain fundamental material in the other course, and 2) a more thorough, applied understanding of the integrated nature of the two subjects. Students will gain an appreciation for the multiple tradeoffs that decision-makers must face in the real world (economy, resources, pollution, health, defense, etc.). Environmental science students will link these concepts to the traditional course material through a "systems thinking" approach to sustainability. Political science students will face the challenges of global climate change and gain an understanding of the nature of

  10. Mechanical ventilation-induced intrathoracic pressure distribution and heart-lung interactions

    NARCIS (Netherlands)

    Lansdorp, Benno; Hofhuizen, C.; van Lavieren, M.A.; van Swieten, H.; Lemson, J.; van Putten, Michel Johannes Antonius Maria; van der Hoeven, J.G.; Pickkers, P.

    2014-01-01

    OBJECTIVE: Mechanical ventilation causes cyclic changes in the heart's preload and afterload, thereby influencing the circulation. However, our understanding of the exact physiology of this cardiopulmonary interaction is limited. We aimed to thoroughly determine airway pressure distribution, how

  11. Mechanical ventilation-induced intrathoracic pressure distribution and heart-lung interactions*

    NARCIS (Netherlands)

    Lansdorp, B.; Hofhuizen, C.M.; Lavieren, M. van; Swieten, H.A. van; Lemson, J.; Putten, M.J.A.M. van; Hoeven, J.G. van der; Pickkers, P.

    2014-01-01

    OBJECTIVE: Mechanical ventilation causes cyclic changes in the heart's preload and afterload, thereby influencing the circulation. However, our understanding of the exact physiology of this cardiopulmonary interaction is limited. We aimed to thoroughly determine airway pressure distribution, how thi

  12. Dynamic Simulations of Combined Transmission and Distribution Systems using Parallel Processing Techniques

    OpenAIRE

    Aristidou, P; Van Cutsem, T

    2014-01-01

    Simulating a power system with both transmission and distribution networks modeled in detail is a huge computational challenge. In this paper, we propose a Schur-complement-based domain decomposition algorithm to provide accurate, detailed dynamic simulations of the combined system. The simulation procedure is accelerated with the use of parallel programming techniques, taking advantage of the parallelization opportunities inherent in domain decomposition algorithms. The proposed algorithm is...

  13. A Parallel Processing Approach to Dynamic Simulations of Combined Transmission and Distribution Systems

    OpenAIRE

    Aristidou, P; Van Cutsem, T

    2015-01-01

    Simulating a power system with both transmission and distribution networks modeled in detail is a huge computational challenge. In this paper, a Schur-complement-based domain decomposition algorithm is proposed to provide accurate, detailed dynamic simulations of such systems. The simulation procedure is accelerated with the use of parallel programming techniques, taking advantage of the parallelization opportunities inherent to domain decomposition algorithms. The proposed algorithm is gener...

  14. Strategic Simulation - Support of Innovation and Operation in Distribution and production Networks

    DEFF Research Database (Denmark)

    Hansen, Mette Sanne

    Today’s business environment is characterized by global competition, changing conditions, and uncertainty. Many Western companies have responded by developing global distribution and production networks. The increasingly challenging business environment and the more complex structure of companies...... or quantitative approaches. Strategic simulation is the combination of narrative and numerical simulation and can be used as a tool to support strategic decision making by providing different scenarios in combination with computer modelling. The core of the combined simulation approach (CSA) is to make...

  15. An iterative approach for modeling the interaction of a partial coherent light distribution with an absorbing photosensitive polymer

    Science.gov (United States)

    Heyvaert, S.; Meuret, Y.; Meulebroeck, W.; Thienpont, H.

    2012-06-01

    The propagation of coherent light through a heterogeneous medium is an often-encountered problem in optics. Analytical solutions, found by solving the appropriate differential equations, usually only exist for simplified and idealized situations limiting their accuracy and applicability. A widely used approach is the Beam Propagation Method in which the electric field is determined by solving the wave equation numerically, making the method time-consuming, a drawback exacerbated by the heterogeneity of the medium. In this work we propose an alternative approach which combines, in an iterative way, optical ray-tracing simulation in the software ASAP™ with numerical simulations in Matlab in order to model the change in light distribution in a medium with anisotropic absorption, exposed to partially coherent light with high irradiance. The medium under study is a photosensitive polymer in which photochemical reactions cause the local absorption to change as a function of the local light fluence. Under continuous illumination, this results in time-varying light distributions throughout the irradiance process. In our model the fluence-absorption interaction is modelled by splitting up each iteration step into two parts. In the first part the optical ray-tracing software determines the new light distribution in the medium using the absorption from the previous iteration step. In the second part, using the new light distribution, the new absorption coefficients are calculated and expressed as a set of polynomials. The evolution of the light distribution and absorption is presented and the change in total transmission is compared with experiments.

  16. Simulation and Analysis of China Climate Using Two-Way Interactive Atmosphere-Vegetation Model (RIEMS-AVIM)

    Institute of Scientific and Technical Information of China (English)

    GAO Rong; DONG Wenjie; WEI Zhigang

    2008-01-01

    In this paper, an Atmosphere-Vegetation Interaction Model (AVIM) is coupled to the Regional Integrated Environment Model System (RIEMS), and a 10-year integration for China is performed using the RIEMS-AVIM. The analysis of the results of the 10-year integration shows that the characters of the spatial distributions of temperature and precipitation over China are well simulated. The patterns of simulated surface sensible and latent heat fluxes match well with the spatial climatological atlas: the values of winter surface sensible and latent heat fluxes are both lower than climatological values over the whole country. Summer surface sensible heat flux is higher than climatological values in western China and lower in eastern China, while summer surface latent heat flux is higher than climatological values in the eastern and lower in the western. Seasonal variations of simulated temperature and precipitation of RIMES-AVIM agree with those of the observed. Simulated temperature is lower than the observed in the Tibetan Plateau and North-west China for the whole year, slightly lower in the remaining regions in winter, but consistent with the observed in summer. The simulated temperature of RIEMS-AVIM is higher in winter and lower in summer than that of RIEMS, which shows that the simulated tempcrature of RIEMS-AVIM is closer to the observed value. Simulated precipitation is excessive in the first half of the year, but consistent with the observed in the second half of the year. The simulated summer precipitation of RIEMS-AVIM has significant improvement compared to that of RIEMS, which is less and closer to the observed value. The interannual variations of temperature and precipitation are also fairly well simulated, with temperature simulation being superior to precipitation simulation. The interannual variation of simulated temperature is significantly correlated with the observed in Northeast China, the Transition Region, South China, and the Tibetan Plateau, but

  17. Comparing simulated and theoretical sampling distributions of the U3 person-fit statistic

    NARCIS (Netherlands)

    Emons, W.H.M.; Meijer, R.R.; Sijtsma, K.

    2002-01-01

    The accuracy with which the theoretical sampling distribution of van der Flier's person-.t statistic U3 approaches the empirical U3 sampling distribution is affected by the item discrimination. A simulation study showed that for tests with a moderate or a strong mean item discrimination, the Type I

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

    CERN Document Server

    Kretz, Tobias

    2012-01-01

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

  19. Nonexistence of interactions between axially symmetric massive scalar field and perfect fluid distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tarachand, R.K.; Singh, N.I.

    1988-07-01

    Considering the axially symmetric Einstein-Rosen metric, the problem of massive scalar field interactions in the presence of perfect fluid distribution has been studied, and it has been observed that there cannot exist any solution for the coupled massive scalar field and perfect fluid distribution for the metric. The problem reduces to the finding of interactions between zero-mass scalar field and stiff fluid.

  20. Differences between Caucasian and Hispanic undergraduates in emphasis on distributive, procedural, and interactional justice.

    Science.gov (United States)

    Tata, J

    2000-08-01

    Most theories of justice focus on individual-level approaches; few examine the role of contextual factors such as culture. To fill this gap in the literature, this study examined the differences between Caucasian and Hispanic undergraduates (n = 120 and 58, respectively) in terms of their emphasis on distributive, procedural, and interactional justice. Analyses indicated that Hispanic students were more likely to use interactional justice than Caucasian respondents, but the groups did not differ in their likelihood of using distributive or procedural justice.

  1. Difference of carboxybetaine and oligo(ethylene glycol) moieties in altering hydrophobic interactions: a molecular simulation study.

    Science.gov (United States)

    Shao, Qing; White, Andrew D; Jiang, Shaoyi

    2014-01-01

    Polycarboxybetaine and poly(ethylene glycol) materials resist nonspecific protein adsorption but differ in influencing biological functions such as enzymatic activity. To investigate this difference, we studied the influence of carboxybetaine and oligo(ethylene glycol) moieties on hydrophobic interactions using molecular simulations. We employed a model system composed of two non-polar plates and studied the potential of mean force of plate-plate association in carboxybetaine, (ethylene glycol)4, and (ethylene glycol)2 solutions using well-tempered metadynamics simulations. Water, trimethylamine N-oxide, and urea solutions were used as reference systems. We analyzed the variation of the potential of mean force in various solutions to study how carboxybetaine and oligo(ethylene glycol) moieties influence the hydrophobic interactions. To study the origin of their influence, we analyzed the normalized distributions of moieties and water molecules using molecular dynamics simulations. The simulation results showed that oligo(ethylene glycol) moieties repel water molecules away from the non-polar plates and weaken the hydrophobic interactions. Carboxybetaine moieties do not repel water molecules away from the plates and therefore do not influence the hydrophobic interactions.

  2. FINITE ELEMENT SIMULATION FOR STRUCTURAL RESPONSE OF U7MO DISPERSION FUEL PLATES VIA FLUID-THERMAL-STRUCTURAL INTERACTION

    Energy Technology Data Exchange (ETDEWEB)

    Hakan Ozaltun; Herman Shen; Pavel Madvedev

    2010-11-01

    This article presents numerical simulation of dispersion fuel mini plates via fluid–thermal–structural interaction performed by commercial finite element solver COMSOL Multiphysics to identify initial mechanical response under actual operating conditions. Since fuel particles are dispersed in Aluminum matrix, and temperatures during the fabrication process reach to the melting temperature of the Aluminum matrix, stress/strain characteristics of the domain cannot be reproduced by using simplified models and assumptions. Therefore, fabrication induced stresses were considered and simulated via image based modeling techniques with the consideration of the high temperature material data. In order to identify the residuals over the U7Mo particles and the Aluminum matrix, a representative SEM image was employed to construct a microstructure based thermo-elasto-plastic FE model. Once residuals and plastic strains were identified in micro-scale, solution was used as initial condition for subsequent multiphysics simulations at the continuum level. Furthermore, since solid, thermal and fluid properties are temperature dependent and temperature field is a function of the velocity field of the coolant, coupled multiphysics simulations were considered. First, velocity and pressure fields of the coolant were computed via fluidstructural interaction. Computed solution for velocity fields were used to identify the temperature distribution on the coolant and on the fuel plate via fluid-thermal interaction. Finally, temperature fields and residual stresses were used to obtain the stress field of the plates via fluid-thermal-structural interaction.

  3. Statics and Dynamics of Selfish Interactions in Distributed Service Systems.

    Directory of Open Access Journals (Sweden)

    Fabrizio Altarelli

    Full Text Available We study a class of games which models the competition among agents to access some service provided by distributed service units and which exhibits congestion and frustration phenomena when service units have limited capacity. We propose a technique, based on the cavity method of statistical physics, to characterize the full spectrum of Nash equilibria of the game. The analysis reveals a large variety of equilibria, with very different statistical properties. Natural selfish dynamics, such as best-response, usually tend to large-utility equilibria, even though those of smaller utility are exponentially more numerous. Interestingly, the latter actually can be reached by selecting the initial conditions of the best-response dynamics close to the saturation limit of the service unit capacities. We also study a more realistic stochastic variant of the game by means of a simple and effective approximation of the average over the random parameters, showing that the properties of the average-case Nash equilibria are qualitatively similar to the deterministic ones.

  4. Statics and Dynamics of Selfish Interactions in Distributed Service Systems.

    Science.gov (United States)

    Altarelli, Fabrizio; Braunstein, Alfredo; Dall'Asta, Luca

    2015-01-01

    We study a class of games which models the competition among agents to access some service provided by distributed service units and which exhibits congestion and frustration phenomena when service units have limited capacity. We propose a technique, based on the cavity method of statistical physics, to characterize the full spectrum of Nash equilibria of the game. The analysis reveals a large variety of equilibria, with very different statistical properties. Natural selfish dynamics, such as best-response, usually tend to large-utility equilibria, even though those of smaller utility are exponentially more numerous. Interestingly, the latter actually can be reached by selecting the initial conditions of the best-response dynamics close to the saturation limit of the service unit capacities. We also study a more realistic stochastic variant of the game by means of a simple and effective approximation of the average over the random parameters, showing that the properties of the average-case Nash equilibria are qualitatively similar to the deterministic ones.

  5. Simulation Calculation and Distribution Characteristics of Terrain Reflected Radiation in Fujian Province

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the distribution characteristics of terrain reflected radiation in Fujian Province.[Method] Based on solar radiation data,digital elevation model (DEM) and surface meteorological observation data in Fujian Province,plus surface albedo obtained by using remote sensing inversion method,the distribution of terrain reflected radiation in Fujian Province from 1988 to 2007 was simulated,and then its temporal and spatial distribution characteristics was studied.[Result] The simulat...

  6. An Experimental Approach to Simulations of the CLIC Interaction Point

    DEFF Research Database (Denmark)

    Esberg, Jakob

    2012-01-01

    an understanding of definitions of processes and quantities that will be used throughout the rest of the thesis. The 7th chapter focuses on the parts of my work that is related to experiment. The main topic is the NA63 Trident experiment which will be discussed in detail. Results of the crystalline undulator...... experiments conducted at MAMI will be presented. Furthermore the chapter discusses the performance of new CMOS based detectors to be used in future experiments by the NA63 collaboration. The chapter on collider simulations introduces the beam-beam simulation codes GUINEA-PIG and GUINEA-PIG++, their methods...... to theoretical ones, and simulations are applied to the 3 TeV CLIC scenario. Here, experimentally based conclusions on the applicability of the theory for strong field production of pairs will be made. In the chapter on depolarization, simulations of the beam-beam depolarization will be presented. The chapter...

  7. Simulations of Energetic Particles Interacting with Dynamical Magnetic Turbulence

    Science.gov (United States)

    Hussein, M.; Shalchi, A.

    2016-02-01

    We explore the transport of energetic particles in interplanetary space by using test-particle simulations. In previous work such simulations have been performed by using either magnetostatic turbulence or undamped propagating plasma waves. In the current paper we simulate for the first time particle transport in dynamical turbulence. To do so we employ two models, namely the damping model of dynamical turbulence and the random sweeping model. We compute parallel and perpendicular diffusion coefficients and compare our numerical findings with solar wind observations. We show that good agreement can be found between simulations and the Palmer consensus range for both dynamical turbulence models if the ratio of turbulent magnetic field and mean field is δB/B0 = 0.5.

  8. Experimental and numerical simulation of air distribution and microorganism pollutant dispersion in gymnasium

    Institute of Scientific and Technical Information of China (English)

    马飞; 霍廖然; 谢慧; 范慧芳

    2009-01-01

    By conducting experimental measurements and numerical simulations of air distribution and microorganism pollutant distribution in the auditorium and game area in a gymnasium,pollutant dispersion control and indoor air quality improvement methods were put forward. The results show that the fungi and bacteria concentration levels are less than the magnitude of 103 CFU (colony-forming units) which meets the requirements of indoor air quality standard. The numerical simulation results quantitatively agree with the experimental data while some differences between theoretical data and experimental data exist in air distributions. People number in gymnasium plays an important role in affecting indoor air quality and the environmental parameters attained the standard.

  9. Traveling Salesman Approach for Solving Petrol Distribution Using Simulated Annealing

    Directory of Open Access Journals (Sweden)

    Zuhaimy Ismail

    2008-01-01

    Full Text Available This research presents an attempt to solve a logistic company's problem of delivering petrol to petrol station in the state of Johor. This delivery system is formulated as a travelling salesman problem (TSP. TSP involves finding an optimal route for visiting stations and returning to point of origin, where the inter-station distance is symmetric and known. This real world application is a deceptive simple combinatorial problem and our approach is to develop solutions based on the idea of local search and meta-heuristics. As a standard problem, we have chosen a solution is a deceptively simple combinatorial problem and we defined it simply as the time spends or distance travelled by salesman visiting n cities (or nodes cyclically. In one tour the vehicle visits each station just once and finishes up where he started. As standard problems, we have chosen TSP with different stations visited once. This research presents the development of solution engine based on local search method known as Greedy Method and with the result generated as the initial solution, Simulated Annealing (SA and Tabu Search (TS further used to improve the search and provide the best solution. A user friendly optimization program developed using Microsoft C++ to solve the TSP and provides solutions to future TSP which may be classified into daily or advanced management and engineering problems.

  10. Anthropogenic litter in urban freshwater ecosystems: distribution and microbial interactions.

    Science.gov (United States)

    Hoellein, Timothy; Rojas, Miguel; Pink, Adam; Gasior, Joseph; Kelly, John

    2014-01-01

    Accumulation of anthropogenic litter (i.e. garbage; AL) and its ecosystem effects in marine environments are well documented. Rivers receive AL from terrestrial habitats and represent a major source of AL to marine environments, but AL is rarely studied within freshwater ecosystems. Our objectives were to 1) quantify AL density in urban freshwaters, 2) compare AL abundance among freshwater, terrestrial, and marine ecosystems, and 3) characterize the activity and composition of AL biofilms in freshwater habitats. We quantified AL from the Chicago River and Chicago's Lake Michigan shoreline, and found that AL abundance in Chicago freshwater ecosystems was comparable to previously reported data for marine and terrestrial ecosystems, although AL density and composition differed among habitats. To assess microbial interactions with AL, we incubated AL and natural substrates in 3 freshwater ecosystems, quantified biofilm metabolism as gross primary production (GPP) and community respiration (CR), and characterized biofilm bacterial community composition via high-throughput sequencing of 16S rRNA genes. The main driver of biofilm community composition was incubation location (e.g., river vs pond), but there were some significant differences in biofilm composition and metabolism among substrates. For example, biofilms on organic substrates (cardboard and leaves) had lower GPP than hard substrates (glass, plastic, aluminum and tiles). In addition, bacterial communities on organic substrates were distinct in composition from those on hard substrates, with higher relative abundances of bacteria associated with cellulose decomposition. Finally, we used our results to develop a conceptual diagram designed to unite the study of AL in terrestrial and freshwater environments with the well-established field of marine debris research. We suggest this broad perspective will be useful for future studies which synthesize AL sources, ecosystem effects, and fate across multiple ecosystem

  11. Deficiencies in the simulation of the geographic distribution of climate types by global climate models

    Science.gov (United States)

    Zhang, Xianliang; Yan, Xiaodong

    2016-05-01

    The performances of General Circulation Models (GCMs) when checked with conventional methods (i.e. correlation, bias, root-mean-square error) can only be evaluated for each variable individually. The geographic distribution of climate type in GCM simulations, which reflects the spatial attributes of models and is related closely to the terrestrial biosphere, has not yet been evaluated. Thus, whether the geographic distribution of climate types was well simulated by GCMs was evaluated in this study for nine GCMs. The results showed that large areas of climate zones classified by the GCMs were allocated incorrectly when compared to the basic climate zones established by observed data. The percentages of wrong areas covered approximately 30-50 % of the total land area for most models. In addition, the temporal shift in the distribution of climate zones according to the GCMs was found to be inaccurate. Not only were the locations of shifts poorly simulated, but also the areas of shift in climate zones. Overall, the geographic distribution of climate types was not simulated well by the GCMs, nor was the temporal shift in the distribution of climate zones. Thus, a new method on how to evaluate the simulated distribution of climate types for GCMs was provided in this study.

  12. The simulated emergence of distributed environmental control in evolving microcosms.

    Science.gov (United States)

    Downing, Keith L

    2002-01-01

    This work continues investigation into Gaia theory [Lovelock, (1995) The ages of Gaia, Oxford University Press] from an artificial life perspective [Downing, (2000) in Proceedings of the 7th International Conference on Artificial Life, (pp. 90-99) MIT Press], with the aim of assessing the general compatibility of emergent distributed environmental control with conventional natural selection. Our earlier system, GUILD [Downing and Zvirinsky, (1999) Artificial Life, 5, 291-318], displayed emergent regulation of the chemical environment by a population of metabolizing agents, but the chemical model underlying those results was trivial, essentially admitting all possible reactions at a single energy cost. The new model, METAMIC, utilizes abstract chemistries that are both (a) constrained to a small set of legal reactions, and (b) grounded in basic fundamental relationships between energy, entropy, and biomass synthesis/breakdown. To explore the general phenomena of emergent homeostasis, we generate 100 different chemistries and use each as the basis for several METAMIC runs, as part of a Gaia hunt. This search discovers 20 chemistries that support microbial populations capable of regulating a physical environmental factor within their growth-optimal range, despite the extra metabolic cost. Case studies from the Gaia hunt illustrate a few simple mechanisms by which real biota might exploit the underlying chemistry to achieve some control over their physical environment. Although these results shed little light on the question of Gaia on Earth, they support the possibility of emergent environmental control at the microcosmic level.

  13. Simulated Galactic methanol maser distribution to constrain Milky Way parameters

    Science.gov (United States)

    Quiroga-Nuñez, L. H.; van Langevelde, H. J.; Reid, M. J.; Green, J. A.

    2017-08-01

    Context. Using trigonometric parallaxes and proper motions of masers associated with massive young stars, the Bar and Spiral Structure Legacy (BeSSeL) survey has reported the most accurate values of the Galactic parameters so far. The determination of these parameters with high accuracy has a widespread impact on Galactic and extragalactic measurements. Aims: This research is aimed at establishing the confidence with which such parameters can be determined. This is relevant for the data published in the context of the BeSSeL survey collaboration, but also for future observations, in particular from the southern hemisphere. In addition, some astrophysical properties of the masers can be constrained, notably the luminosity function. Methods: We have simulated the population of maser-bearing young stars associated with Galactic spiral structure, generating several samples and comparing them with the observed samples used in the BeSSeL survey. Consequently, we checked the determination of Galactic parameters for observational biases introduced by the sample selection. Results: Galactic parameters obtained by the BeSSeL survey do not seem to be biased by the sample selection used. In fact, the published error estimates appear to be conservative for most of the parameters. We show that future BeSSeL data and future observations with southern arrays will improve the Galactic parameters estimates and smoothly reduce their mutual correlation. Moreover, by modeling future parallax data with larger distance values and, thus, greater relative uncertainties for a larger numbers of sources, we found that parallax-distance biasing is an important issue. Hence, using fractional parallax uncertainty in the weighting of the motion data is imperative. Finally, the luminosity function for 6.7 GHz methanol masers was determined, allowing us to estimate the number of Galactic methanol masers.

  14. Geant4 Simulation Study of Deep Underground Muons: Vertical Intensity and Angular Distribution

    Directory of Open Access Journals (Sweden)

    Halil Arslan

    2013-01-01

    Full Text Available Underground muon intensities up to 10000 m.w.e. and angular distribution up to 6500 m.w.e. in standard rock have been investigated using Geant4 simulation package. Muons with energies above 100 GeV were distributed from the ground level taking into account the muon charge ratio of ~1.3 at sea level. The simulated differential muon intensities are in good agreement with the intensities given in the literature. Furthermore, the simulation results for the integrated intensities are consistent with the experimental data, particularly at depths above 4000 m.w.e., where the simulation gives slightly smaller intensities than the experimental ones. In addition, the simulated exponent n at different underground depths agrees well with the experimental points, especially above ~2000 m.w.e.

  15. SIMULATION OF AIRCRAFT CONDENSATION TRAILS AND WAKE VORTICES INTERACTION

    Directory of Open Access Journals (Sweden)

    T. O. Aubakirov

    2015-01-01

    Full Text Available A technique of calculation of aircraft condensation trails (contrails and wake vortices interaction is described. The technique is based on a suitable for real-time applications mathematical model of far wake utilizes the method of discrete vortices. The technique is supplemented by account of the influence of axial velocities in the vortex nucleus on contrail and wake vortex location. Results of calculations of contrails and wake vortices interaction for Il-76 and B-747 aircraft are presented.

  16. Towards an Information Model of Consistency Maintenance in Distributed Interactive Applications

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2008-01-01

    Full Text Available A novel framework to model and explore predictive contract mechanisms in distributed interactive applications (DIAs using information theory is proposed. In our model, the entity state update scheme is modelled as an information generation, encoding, and reconstruction process. Such a perspective facilitates a quantitative measurement of state fidelity loss as a result of the distribution protocol. Results from an experimental study on a first-person shooter game are used to illustrate the utility of this measurement process. We contend that our proposed model is a starting point to reframe and analyse consistency maintenance in DIAs as a problem in distributed interactive media compression.

  17. Reliability Assessment of Active Distribution System Using Monte Carlo Simulation Method

    Directory of Open Access Journals (Sweden)

    Shaoyun Ge

    2014-01-01

    Full Text Available In this paper we have treated the reliability assessment problem of low and high DG penetration level of active distribution system using the Monte Carlo simulation method. The problem is formulated as a two-case program, the program of low penetration simulation and the program of high penetration simulation. The load shedding strategy and the simulation process were introduced in detail during each FMEA process. Results indicate that the integration of DG can improve the reliability of the system if the system was operated actively.

  18. Bone drilling haptic interaction for orthopedic surgical simulator.

    Science.gov (United States)

    Tsai, Ming-Dar; Hsieh, Ming-Shium; Tsai, Chiung-Hsin

    2007-12-01

    Drilling procedure is widely used in orthopedic surgery to position reduced fractured bones and prosthetic components. However, successful execution of bone drilling requires a high level of dexterity and experience, because the drilling resistance is large and sometimes vibrates violently to difficultly grasp the hand-piece or even break the slender drill. This paper introduces haptic functions that are added to a volume based surgical simulator to simulate the drilling process. These haptic functions compute drilling forces and torques based on reliable metal removing theorem. Therefore, accurate prediction for the drilling process can be obtained to provide effective surgery training and rehearsal. A simulation example of screw and plate surgery for positioning the hip trochanter fracture illustrates the practicality and versatility of the proposed method.

  19. Observation and simulation of space-charge effects in a radio-frequency photoinjector using a transverse multibeamlet distribution

    Directory of Open Access Journals (Sweden)

    M. Rihaoui

    2009-12-01

    Full Text Available We report on an experimental study of space-charge effects in a radio-frequency (rf photoinjector. A 5 MeV electron bunch, consisting of a number of beamlets separated transversely, was generated in an rf photocathode gun and propagated in the succeeding drift space. The collective interaction of these beamlets was studied for different experimental conditions. The experiment allowed the exploration of space-charge effects and its comparison with 3D particle-in-cell simulations. Our observations also suggest the possible use of a multibeam configuration to tailor the transverse distribution of an electron beam.

  20. Advances in Simulation of Wave Interactions with Extended MHD Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, Donald B [ORNL; D' Azevedo, Eduardo [ORNL; Bateman, Glenn [ORNL; Bernholdt, David E [ORNL; Bonoli, P. [Massachusetts Institute of Technology (MIT); Bramley, Randall B [ORNL; Breslau, Joshua [ORNL; Elwasif, Wael R [ORNL; Foley, S. [Indiana University; Jaeger, Erwin Frederick [ORNL; Jardin, S. C. [Princeton Plasma Physics Laboratory (PPPL); Klasky, Scott A [ORNL; Kruger, Scott E [ORNL; Ku, Long-Poe [ORNL; McCune, Douglas [Princeton Plasma Physics Laboratory (PPPL); Ramos, J. [Massachusetts Institute of Technology (MIT); Schissel, David P [ORNL; Schnack, Dalton D [ORNL

    2009-01-01

    The Integrated Plasma Simulator (IPS) provides a framework within which some of the most advanced, massively-parallel fusion modeling codes can be interoperated to provide a detailed picture of the multi-physics processes involved in fusion experiments. The presentation will cover four topics: (1) recent improvements to the IPS, (2) application of the IPS for very high resolution simulations of ITER scenarios, (3) studies of resistive and ideal MHD stability in tokamak discharges using IPS facilities, and (4) the application of RF power in the electron cyclotron range of frequencies to control slowly growing MHD modes in tokamaks and initial evaluations of optimized location for RF power deposition.

  1. Advances in Simulation of Wave Interaction with Extended MHD Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, Donald B [ORNL; Abla, Gheni [ORNL; D' Azevedo, Ed F [ORNL; Bateman, Glenn [Lehigh University, Bethlehem, PA; Bernholdt, David E [ORNL; Berry, Lee A [ORNL; Bonoli, P. [Massachusetts Institute of Technology (MIT); Bramley, R [Indiana University; Breslau, Joshua [ORNL; Chance, M. [Princeton Plasma Physics Laboratory (PPPL); Chen, J. [Princeton Plasma Physics Laboratory (PPPL); Choi, M. [General Atomics; Elwasif, Wael R [ORNL; Foley, S. [Indiana University; Fu, GuoYong [Princeton Plasma Physics Laboratory (PPPL); Harvey, R. W. [CompX, Del Mar, CA; Jaeger, Erwin Frederick [ORNL; Jardin, S. C. [Princeton Plasma Physics Laboratory (PPPL); Jenkins, T [University of Wisconsin; Keyes, David E [Columbia University; Klasky, Scott A [ORNL; Kruger, Scott [Tech-X Corporation; Ku, Long-Poe [Princeton Plasma Physics Laboratory (PPPL); Lynch, Vickie E [ORNL; McCune, Douglas [Princeton Plasma Physics Laboratory (PPPL); Ramos, J. [Massachusetts Institute of Technology (MIT); Schissel, D. [General Atomics; Schnack, [University of Wisconsin; Wright, J. [Massachusetts Institute of Technology (MIT)

    2009-01-01

    The Integrated Plasma Simulator (IPS) provides a framework within which some of the most advanced, massively-parallel fusion modeling codes can be interoperated to provide a detailed picture of the multi-physics processes involved in fusion experiments. The presentation will cover four topics: 1) recent improvements to the IPS, 2) application of the IPS for very high resolution simulations of ITER scenarios, 3) studies of resistive and ideal MHD stability in tokamk discharges using IPS facilities, and 4) the application of RF power in the electron cyclotron range of frequencies to control slowly growing MHD modes in tokamaks and initial evaluations of optimized location for RF power deposition.

  2. Advances in simulation of wave interactions with extended MHD phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, D; D' Azevedo, E; Bernholdt, D E; Berry, L; Elwasif, W; Jaeger, E [Oak Ridge National Laboratory (United States); Abla, G; Choi, M [General Atomics (United States); Bateman, G [Lehigh University (United States); Bonoli, P [Plasma Science and Fusion Center, Massachusetts Institute of Technology (United States); Bramley, R; Foley, S [Indiana University (United States); Breslau, J; Chance, M; Chen, J; Fu, G; Jardin, S [Princeton Plasma Physics Laboratory (United States); Harvey, R [CompX International (United States); Jenkins, T [University of Wisconsin (United States); Keyes, D, E-mail: batchelordb@ornl.go [Columbia University (United States)

    2009-07-01

    The Integrated Plasma Simulator (IPS) provides a framework within which some of the most advanced, massively-parallel fusion modeling codes can be interoperated to provide a detailed picture of the multi-physics processes involved in fusion experiments. The presentation will cover four topics: 1) recent improvements to the IPS, 2) application of the IPS for very high resolution simulations of ITER scenarios, 3) studies of resistive and ideal MHD stability in tokamk discharges using IPS facilities, and 4) the application of RF power in the electron cyclotron range of frequencies to control slowly growing MHD modes in tokamaks and initial evaluations of optimized location for RF power deposition.

  3. APPLICATION OF INTERACTIVE ONLINE SIMULATIONS IN THE PHYSICS LABORATORY ACTIVITIES

    Directory of Open Access Journals (Sweden)

    Nina P. Dementievska

    2013-09-01

    Full Text Available Physics teachers should have professional competences, aimed at the use of online technologies associated with physical experiments. Lack of teaching materials for teachers in Ukrainian language leads to the use of virtual laboratories and computer simulations by traditional methods of education, not by the latest innovative modern educational technology, which may limit their use and greatly reduce their effectiveness. Ukrainian teaching literature has practically no information about the assessment of competencies, research skills of students for the laboratory activities. The aim of the article is to describe some components of instructional design for the Web site with simulations in school physical experiments and their evaluation.

  4. Simulation and optimization of logistics distribution for an engine production line

    Directory of Open Access Journals (Sweden)

    Lijun Song

    2016-02-01

    Full Text Available Purpose: In order to analyze and study the factors about Logistics distribution system, solve the problems of out of stock on the production line and improve the efficiency of the assembly line. Design/methodology/approach: Using the method of industrial engineering, put forward the optimization scheme of distribution system. The simulation model of logistics distribution system for engine assembly line was build based on Witness software. Findings: The optimization plan is efficient to improve Logistics distribution efficiency, production of assembly line efficiency and reduce the storage of production line Originality/value: Based on the study of the modeling and simulation of engine production logistics distribution system, the result reflects some influence factors about production logistics system, which has reference value to improving the efficiency of the production line.

  5. Internet of Things: a possible change in the distributed modeling and simulation architecture paradigm

    Science.gov (United States)

    Riecken, Mark; Lessmann, Kurt; Schillero, David

    2016-05-01

    The Data Distribution Service (DDS) was started by the Object Management Group (OMG) in 2004. Currently, DDS is one of the contenders to support the Internet of Things (IoT) and the Industrial IOT (IIoT). DDS has also been used as a distributed simulation architecture. Given the anticipated proliferation of IoT and II devices, along with the explosive growth of sensor technology, can we expect this to have an impact on the broader community of distributed simulation? If it does, what is the impact and which distributed simulation domains will be most affected? DDS shares many of the same goals and characteristics of distributed simulation such as the need to support scale and an emphasis on Quality of Service (QoS) that can be tailored to meet the end user's needs. In addition, DDS has some built-in features such as security that are not present in traditional distributed simulation protocols. If the IoT and II realize their potential application, we predict a large base of technology to be built around this distributed data paradigm, much of which could be directly beneficial to the distributed M&S community. In this paper we compare some of the perceived gaps and shortfalls of current distributed M&S technology to the emerging capabilities of DDS built around the IoT. Although some trial work has been conducted in this area, we propose a more focused examination of the potential of these new technologies and their applicability to current and future problems in distributed M&S. The Internet of Things (IoT) and its data communications mechanisms such as the Data Distribution System (DDS) share properties in common with distributed modeling and simulation (M&S) and its protocols such as the High Level Architecture (HLA) and the Test and Training Enabling Architecture (TENA). This paper proposes a framework based on the sensor use case for how the two communities of practice (CoP) can benefit from one another and achieve greater capability in practical distributed

  6. Limitations of fibre optic distributed temperature sensing for quantifying surface water groundwater interactions

    Directory of Open Access Journals (Sweden)

    H. Roshan

    2014-07-01

    Full Text Available Studies of surface water–groundwater interactions using fiber optic distributed temperature sensing (FO-DTS has increased in recent years. However, only a few studies to date have explored the limitations of FO-DTS in detecting groundwater discharge to streams. A FO_DTS system was therefore tested in a flume under controlled laboratory conditions for its ability to accurately measure the discharge of hot or cold groundwater into a simulated surface water flow. In the experiment the surface water (SW and groundwater (GW velocities, expressed as ratios (vgw/vsw, were varied from 0.21% to 61.7%; temperature difference between SW-GW were varied from 2 to 10 °C; the direction of temperature gradient were varied with both cold and-hot water injection; and two different bed materials were used to investigate their effects on FO_DTS's detection limit of groundwater discharge. The ability of the FO_DTS system to detect the discharge of groundwater of a different temperature in the laboratory environment was found to be mainly dependent upon the surface and groundwater flow velocities and their temperature difference. A correlation was proposed to estimate the groundwater discharge from temperature. The correlation is valid when the ratio of the apparent temperature response to the source temperature difference is above 0.02.

  7. Variability of daily winter wind speed distribution over Northern Europe during the past millennium in regional and global climate simulations

    Science.gov (United States)

    Bierstedt, Svenja; Hünicke, Birgit; Zorita, Eduardo; Wagner, Sebastian; José Gomez-Navarro, Juán

    2016-04-01

    daily wind speed statistics can be inferred from these simulations. The understanding of past and future changes in the distribution of wind speeds, and thus of wind speed extremes, will require a detailed analysis of the representation of the interaction between large-scale and small-scale dynamics.

  8. Simulating social interactions for the experimental investigation of joint attention.

    Science.gov (United States)

    Caruana, Nathan; McArthur, Genevieve; Woolgar, Alexandra; Brock, Jon

    2017-03-01

    Social interactions are, by their nature, dynamic and reciprocal - your behaviour affects my behaviour, which affects your behaviour in return. However, until recently, the field of social cognitive neuroscience has been dominated by paradigms in which participants passively observe social stimuli from a detached "third person" perspective. Here we consider the unique conceptual and methodological challenges involved in adopting a "second person" approach whereby social cognitive mechanisms and their neural correlates are investigated within social interactions (Schilbach et al., 2013). The key question for researchers is how to distil a complex, intentional interaction between two individuals into a tightly controlled and replicable experimental paradigm. We explore these issues within the context of recent investigations of joint attention - the ability to coordinate a common focus of attention with another person. We review pioneering neurophysiology and eye-tracking studies that have begun to address these issues; offer recommendations for the optimal design and implementation of interactive tasks, and discuss the broader implications of interactive approaches for social cognitive neuroscience.

  9. A Guide for Developing Human-Robot Interaction Experiments in the Robotic Interactive Visualization and Experimentation Technology (RIVET) Simulation

    Science.gov (United States)

    2016-05-01

    camera control for remote exploration. In: Proceedings of ACM CHI 2004 Conference on Human Factors in Computing Systems; 2004 Apr 24–29; Vienna...Austria. New York (NY): ACM ; c2004. p. 511–517. Kunkler K. The role of medical simulation: an overview. The International Journal of Medical Robotics and...Schreckenghost D. Survey of metrics for human-robot interaction. In: Proceedings of the 8th ACM /IEEE Human-Robot Interaction Conference; HRI 2013

  10. Ensemble-Biased Metadynamics: A Molecular Simulation Method to Sample Experimental Distributions.

    Science.gov (United States)

    Marinelli, Fabrizio; Faraldo-Gómez, José D

    2015-06-16

    We introduce an enhanced-sampling method for molecular dynamics (MD) simulations referred to as ensemble-biased metadynamics (EBMetaD). The method biases a conventional MD simulation to sample a molecular ensemble that is consistent with one or more probability distributions known a priori, e.g., experimental intramolecular distance distributions obtained by double electron-electron resonance or other spectroscopic techniques. To this end, EBMetaD adds an adaptive biasing potential throughout the simulation that discourages sampling of configurations inconsistent with the target probability distributions. The bias introduced is the minimum necessary to fulfill the target distributions, i.e., EBMetaD satisfies the maximum-entropy principle. Unlike other methods, EBMetaD does not require multiple simulation replicas or the introduction of Lagrange multipliers, and is therefore computationally efficient and straightforward in practice. We demonstrate the performance and accuracy of the method for a model system as well as for spin-labeled T4 lysozyme in explicit water, and show how EBMetaD reproduces three double electron-electron resonance distance distributions concurrently within a few tens of nanoseconds of simulation time. EBMetaD is integrated in the open-source PLUMED plug-in (www.plumed-code.org), and can be therefore readily used with multiple MD engines.

  11. Simulation of product distribution at PT Anugrah Citra Boga by using capacitated vehicle routing problem method

    Science.gov (United States)

    Lamdjaya, T.; Jobiliong, E.

    2017-01-01

    PT Anugrah Citra Boga is a food processing industry that produces meatballs as their main product. The distribution system of the products must be considered, because it needs to be more efficient in order to reduce the shipment cost. The purpose of this research is to optimize the distribution time by simulating the distribution channels with capacitated vehicle routing problem method. Firstly, the distribution route is observed in order to calculate the average speed, time capacity and shipping costs. Then build the model using AIMMS software. A few things that are required to simulate the model are customer locations, distances, and the process time. Finally, compare the total distribution cost obtained by the simulation and the historical data. It concludes that the company can reduce the shipping cost around 4.1% or Rp 529,800 per month. By using this model, the utilization rate can be more optimal. The current value for the first vehicle is 104.6% and after the simulation it becomes 88.6%. Meanwhile, the utilization rate of the second vehicle is increase from 59.8% to 74.1%. The simulation model is able to produce the optimal shipping route with time restriction, vehicle capacity, and amount of vehicle.

  12. PhET Interactive Simulations: Transformative Tools for Teaching Chemistry

    Science.gov (United States)

    Moore, Emily B.; Chamberlain, Julia M.; Parson, Robert; Perkins, Katherine K.

    2014-01-01

    Developing fluency across symbolic-, macroscopic-, and particulate-level representations is central to learning chemistry. Within the chemistry education community, animations and simulations that support multi-representational fluency are considered critical. With advances in the accessibility and sophistication of technology,…

  13. Simulating market dynamics : Interactions between consumer psychology and social networks

    NARCIS (Netherlands)

    Janssen, MA; Jager, W

    2003-01-01

    Markets can show different types of dynamics, from quiet markets dominated by one or a few products, to markets with continual penetration of new and reintroduced products. in a previous article we explored the dynamics of markets from a psychological perspective using a multi-agent simulation model

  14. Simulation of interaction between wind farm and power system

    DEFF Research Database (Denmark)

    Sørensen, Poul Ejnar; Hansen, Anca Daniela; Janosi, L.

    2002-01-01

    A dynamic model of the wind farm Hagesholm has been implemented in the dedicated power system simulation program DIgSILENT. The wind farm con- sists of six 2MW NM2000/72 wind turbines from NEG-Micon. The model has been verified using simultaneous powerquality measurements on the 10 kV terminals...

  15. Compressible simulation of rotor-stator interaction in pump-turbines

    Energy Technology Data Exchange (ETDEWEB)

    Yan, J; Koutnik, J; Seidel, U; Huebner, B, E-mail: jianping.yan@voith.co [Voith Hydro Holding GmbH and Co. KG Alexanderstr. 11, 89522 Heidenheim (Germany)

    2010-08-15

    This work investigates the influence of water compressibility on pressure pulsations induced by rotor-stator interaction (RSI) in hydraulic machinery, using the commercial CFD solver ANSYS-CFX. A pipe flow example with harmonic velocity excitation at the inlet plane is simulated using different grid densities and time step sizes. Results are compared with a validated code for hydraulic networks (SIMSEN). Subsequently, the solution procedure is applied to a simplified 2.5-dimensional pump-turbine configuration in model scale with an adapted speed of sound. Pressure fluctuations are compared with numerical and experimental data based on prototype scale. The good agreement indicates that the scaling of acoustic effects with an adapted speed of sound works well. Finally, the procedure is applied to a 3-dimensional pump configuration in model scale. Pressure fluctuations are compared with results from prototype measurements. Compared to incompressible computations, compressible simulations provide similar pressure fluctuations in vaneless space, but pressure fluctuations in spiral case and penstock may be much higher. With respect to pressure fluctuation amplitudes along the centerline of runner channels, incompressible solutions exhibit a linear decrease while compressible solutions exhibit sinusoidal distributions with maximum values at half the channel length, coinciding with analytical solutions of one-dimensional acoustics.

  16. Interaction of amyloid inhibitor proteins with amyloid beta peptides: insight from molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Payel Das

    Full Text Available Knowledge of the detailed mechanism by which proteins such as human αB- crystallin and human lysozyme inhibit amyloid beta (Aβ peptide aggregation is crucial for designing treatment for Alzheimer's disease. Thus, unconstrained, atomistic molecular dynamics simulations in explicit solvent have been performed to characterize the Aβ17-42 assembly in presence of the αB-crystallin core domain and of lysozyme. Simulations reveal that both inhibitor proteins compete with inter-peptide interaction by binding to the peptides during the early stage of aggregation, which is consistent with their inhibitory action reported in experiments. However, the Aβ binding dynamics appear different for each inhibitor. The binding between crystallin and the peptide monomer, dominated by electrostatics, is relatively weak and transient due to the heterogeneous amino acid distribution of the inhibitor surface. The crystallin-bound Aβ oligomers are relatively long-lived, as they form more extensive contact surface with the inhibitor protein. In contrast, a high local density of arginines from lysozyme allows strong binding with Aβ peptide monomers, resulting in stable complexes. Our findings not only illustrate, in atomic detail, how the amyloid inhibitory mechanism of human αB-crystallin, a natural chaperone, is different from that of human lysozyme, but also may aid de novo design of amyloid inhibitors.

  17. A variational constitutive model for the distribution and interactions of multi-sized voids

    KAUST Repository

    Liu, Jinxing

    2013-07-29

    The evolution of defects or voids, generally recognized as the basic failure mechanism in most metals and alloys, has been intensively studied. Most investigations have been limited to spatially periodic cases with non-random distributions of the radii of the voids. In this study, we use a new form of the incompressibility of the matrix to propose the formula for the volumetric plastic energy of a void inside a porous medium. As a consequence, we are able to account for the weakening effect of the surrounding voids and to propose a general model for the distribution and interactions of multi-sized voids. We found that the single parameter in classical Gurson-type models, namely void volume fraction is not sufficient for the model. The relative growth rates of voids of different sizes, which can in principle be obtained through physical or numerical experiments, are required. To demonstrate the feasibility of the model, we analyze two cases. The first case represents exactly the same assumption hidden in the classical Gurson\\'s model, while the second embodies the competitive mechanism due to void size differences despite in a much simpler manner than the general case. Coalescence is implemented by allowing an accelerated void growth after an empirical critical porosity in a way that is the same as the Gurson-Tvergaard-Needleman model. The constitutive model presented here is validated through good agreements with experimental data. Its capacity for reproducing realistic failure patterns is shown by simulating a tensile test on a notched round bar. © 2013 The Author(s).

  18. Simulation of folding of a small alpha-helical protein in atomistic detail using worldwide-distributed computing.

    Science.gov (United States)

    Zagrovic, Bojan; Snow, Christopher D; Shirts, Michael R; Pande, Vijay S

    2002-11-08

    By employing thousands of PCs and new worldwide-distributed computing techniques, we have simulated in atomistic detail the folding of a fast-folding 36-residue alpha-helical protein from the villin headpiece. The total simulated time exceeds 300 micros, orders of magnitude more than previous simulations of a molecule of this size. Starting from an extended state, we obtained an ensemble of folded structures, which is on average 1.7A and 1.9A away from the native state in C(alpha) distance-based root-mean-square deviation (dRMS) and C(beta) dRMS sense, respectively. The folding mechanism of villin is most consistent with the hydrophobic collapse view of folding: the molecule collapses non-specifically very quickly ( approximately 20ns), which greatly reduces the size of the conformational space that needs to be explored in search of the native state. The conformational search in the collapsed state appears to be rate-limited by the formation of the aromatic core: in a significant fraction of our simulations, the C-terminal phenylalanine residue packs improperly with the rest of the hydrophobic core. We suggest that the breaking of this interaction may be the rate-determining step in the course of folding. On the basis of our simulations we estimate the folding rate of villin to be approximately 5micros. By analyzing the average features of the folded ensemble obtained by simulation, we see that the mean folded structure is more similar to the native fold than any individual folded structure. This finding highlights the need for simulating ensembles of molecules and averaging the results in an experiment-like fashion if meaningful comparison between simulation and experiment is to be attempted. Moreover, our results demonstrate that (1) the computational methodology exists to simulate the multi-microsecond regime using distributed computing and (2) that potential sets used to describe interatomic interactions may be sufficiently accurate to reach the folded state

  19. DIANE - Distributed analysis environment for GRID-enabled simulation and analysis of physics data

    CERN Document Server

    Moscicki, Jakub T

    2003-01-01

    Distributed ANalysis Environment (DIANE) is the result of R&D in CERN IT Division focused on interfacing semiinteractive parallel applications with distributed GRID technology. DIANE provides a master-worker workflow management layer above low-level GRID services. DIANE is application and language-neutral. Component- container architecture and component adapters provide flexibility necessary to fulfill the diverse requirements of distributed applications. Physical Transport Layer assures interoperability with existing middleware frameworks based on Web Services. Several distributed simulations based on Geant 4 were deployed and tested in real-life scenarios with DIANE.

  20. Molecular dynamics simulation of nanoscale distribution and mobility of water and dimethylmethylphosphonate in sulfonated polystyrene.

    Science.gov (United States)

    Vishnyakov, Aleksey; Neimark, Alexander V

    2008-11-27

    The interest in a better understanding of the specific interactions of phosphor-organic compounds and water with sulfonated polystyrene (sPS) is motivated by the use of block copolymers as protective membranes against chemical warfare agents. Using classical molecular dynamics simulations, we explored the nanoscale segregation and diffusion of water and nerve gas simulant dimethylmethylphosphonate (DMMP) in sPS neutralized with calcium counterions at different sulfonation and hydration levels. The water content was varied from 15 to 54% of dry polymer weight, and the DMMP content was varied from 0 to 100 wt %. We found that, in the 40% sulfonated polystyrene, water forms well defined aggregates, which grow in size as the hydration increases, reaching approximately 20 A at the maximum water content. In the 100% sulfonated polystyrene, the overall structure of hydrated polymer is more uniform with smaller water aggregates. Diffusion of water at the same number of water molecules per sulfonate group is faster at a lower sulfonation level. The solvation of sPS in water-DMMP binary mixtures was found to differ substantially from Nafion, where DMMP forms a layer between the hydropholic and hydrophobic subphases. In sPS with divalent Ca(2+) counterions, DMMP and water compete for the solvation of the sulfonate group. At high water and DMMP contents, the diffusion of DMMP turned out to be rather fast with a diffusion coefficient of ca. 30% of that of water. At the same time, water diffusion slows down as the DMMP concentration increases. This observation suggests that although sPS is permeable for both solvents, water and DMMP are partially segregated on the scale of 1-2 nm and have different pathways through the system. The nonuniform nanoscale distribution of water and DMMP in sPS is confirmed by analyses of different pair correlation functions. This feature may significantly affect the perm-selective properties of sPS-contained block copolymer membranes.

  1. Modeling and Simulation of Power Distribution System in More Electric Aircraft

    Directory of Open Access Journals (Sweden)

    Zhangang Yang

    2015-01-01

    Full Text Available The More Electric Aircraft concept is a fast-developing trend in modern aircraft industry. With this new concept, the performance of the aircraft can be further optimized and meanwhile the operating and maintenance cost will be decreased effectively. In order to optimize the power system integrity and have the ability to investigate the performance of the overall system in any possible situations, one accurate simulation model of the aircraft power system will be very helpful and necessary. This paper mainly introduces a method to build a simulation model for the power distribution system, which is based on detailed component models. The power distribution system model consists of power generation unit, transformer rectifier unit, DC-DC converter unit, and DC-AC inverter unit. In order to optimize the performance of the power distribution system and improve the quality of the distributed power, a feedback control network is designed based on the characteristics of the power distribution system. The simulation result indicates that this new simulation model is well designed and it works accurately. Moreover, steady state performance and transient state performance of the model can fulfill the requirements of aircraft power distribution system in the realistic application.

  2. Initial and Final State Interaction Effects in Small-x Quark Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bo-Wen; Yuan, Feng

    2010-08-30

    We study the initial and final state interaction effects in the transverse momentum dependent parton distributions in the small-x saturation region. In particular, we discuss the quark distributions in the semi-inclusive deep inelastic scattering, Drell-Yan lepton pair production and dijet-correlation processes in pA collisions. We calculate the quark distributions in the scalar-QED model and then extend to the color glass condensate formalism in QCD. The quark distributions are found universal between the DIS and Drell-Yan processes. On the other hand, the quark distribution from the qq'-->qq' channel contribution to the dijet-correlation process is not universal. However, we find that it can be related to the quark distribution in DIS process by a convolution with the normalized unintegrated gluon distribution in the CGC formalism in the large Nc limit.

  3. Simulation of diatomic gas-wall interaction and accommodation coefficients for negative ion sources and accelerators

    Science.gov (United States)

    Sartori, E.; Brescaccin, L.; Serianni, G.

    2016-02-01

    Particle-wall interactions determine in different ways the operating conditions of plasma sources, ion accelerators, and beams operating in vacuum. For instance, a contribution to gas heating is given by ion neutralization at walls; beam losses and stray particle production—detrimental for high current negative ion systems such as beam sources for fusion—are caused by collisional processes with residual gas, with the gas density profile that is determined by the scattering of neutral particles at the walls. This paper shows that Molecular Dynamics (MD) studies at the nano-scale can provide accommodation parameters for gas-wall interactions, such as the momentum accommodation coefficient and energy accommodation coefficient: in non-isothermal flows (such as the neutral gas in the accelerator, coming from the plasma source), these affect the gas density gradients and influence efficiency and losses in particular of negative ion accelerators. For ideal surfaces, the computation also provides the angular distribution of scattered particles. Classical MD method has been applied to the case of diatomic hydrogen molecules. Single collision events, against a frozen wall or a fully thermal lattice, have been simulated by using probe molecules. Different modelling approximations are compared.

  4. The interaction between electrolyte and surfaces decorated with charged groups: A molecular dynamics simulation study.

    Science.gov (United States)

    Calero, Carles; Faraudo, Jordi

    2010-01-14

    In this paper, we perform molecular dynamics simulations of an interface containing charged functional groups of different valences in contact with 2:1 ionic solution. We take into account both the finite sizes of the ions in solution and the functional groups but we neglect the structural details of the solvent (primitive model). We show that the distribution of ions and the electrostatic properties of the system depend strongly on the valence of the interfacial charged groups. In the case of surfaces containing well-separated charged interfacial groups, we observe counterion binding at these groups induced by electrostatic interactions. A detailed analysis of the potential of mean force between interfacial charged groups and ions reveals significant features not anticipated by present theories of electrolytes near interfaces. Overall, our results show that, in primitive models of the ion-interface interaction, not only the ionic size and valence are important but the size and valence of the interfacial charged groups also have a significant impact.

  5. Implementation of Parallel Dynamic Simulation on Shared-Memory vs. Distributed-Memory Environments

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Shuangshuang; Chen, Yousu; Wu, Di; Diao, Ruisheng; Huang, Zhenyu

    2015-12-09

    Power system dynamic simulation computes the system response to a sequence of large disturbance, such as sudden changes in generation or load, or a network short circuit followed by protective branch switching operation. It consists of a large set of differential and algebraic equations, which is computational intensive and challenging to solve using single-processor based dynamic simulation solution. High-performance computing (HPC) based parallel computing is a very promising technology to speed up the computation and facilitate the simulation process. This paper presents two different parallel implementations of power grid dynamic simulation using Open Multi-processing (OpenMP) on shared-memory platform, and Message Passing Interface (MPI) on distributed-memory clusters, respectively. The difference of the parallel simulation algorithms and architectures of the two HPC technologies are illustrated, and their performances for running parallel dynamic simulation are compared and demonstrated.

  6. A solution of multidisciplinary collaborative simulation for complex engineering systems in a distributed heterogeneous environment

    Institute of Scientific and Technical Information of China (English)

    ZHANG HeMing

    2009-01-01

    This paper presents an integrated approach to multidisciplinary collaborative simulation for complex engineering systems. The formulized paradigm of mulUdisciplinary collaborative simulation for com-plex engineering systems is principally analyzed. An IEEE HLA and web services based framework is proposed to provide a heterogeneous, distributed and collaborative running environment where multi-disciplinary modeling, running management and post-processing of collaborative simulation are under-taken. The mechanism of multidisciplinary collaborative modeling, disciplinary model transformation, and time-synchronized simulation advancement are studied in detail. A prototype with the functions of multidisciplinary modeling, running management and post-processing for collaborative simulations is developed, and a typical complex engineering system is chosen as a case study to demonstrate the effectiveness of this new approach towards collaborative simulation.

  7. Estimating and Measuring Application Latency of Typical Distributed Interactive Simulation (DIS)-Based Simulation Architecture

    Science.gov (United States)

    2013-03-01

    Bottazzi & Salati, 1991). A variant of the model-view-controller ( MVC ) design pattern is typically used to create these types of multithreaded... pattern . The thread rates of the software design play a significant role in determining the state data consistency and are the focus of this...act as a means to find several of the performance metrics. Note that in Figure 6, as 31 drawn, there is a symmetric pattern for all the timestamps

  8. Numerical Simulation of Shock(Blast)Wave Interaction with Bodies

    Institute of Scientific and Technical Information of China (English)

    JialingLE

    1999-01-01

    Some typical results of computation on the shock(blast)wave interaction (2-D and 3-D) with bodies and its experimental validation in shock tube are summarized,suggestions for improving the numerical method(Difference scheme and grid systems).developing 3-D optical quantitative visualization technology and further studying the unsteady turbulent flow are put forward.

  9. Humans, computers and wizards human (simulated) computer interaction

    CERN Document Server

    Fraser, Norman; McGlashan, Scott; Wooffitt, Robin

    2013-01-01

    Using data taken from a major European Union funded project on speech understanding, the SunDial project, this book considers current perspectives on human computer interaction and argues for the value of an approach taken from sociology which is based on conversation analysis.

  10. Enhancing the NS-2 Network Simulator for Near Real-Time Control Feedback and Distributed Simulation

    Science.gov (United States)

    2009-03-21

    introduction of a mediator to synchronize events is often used. Branicky et al [5] outlines a framework for co-simulation with a networked control system providing...accessed on Nov 4, 2008. Http://www.boost.org/. 5. Branicky, Michael, Vincenzo Liberatore, and Stephen M. Phillips. “ Networked Control System Co

  11. Social interaction, globalization and computer-aided analysis a practical guide to developing social simulation

    CERN Document Server

    Osherenko, Alexander

    2014-01-01

    This thorough, multidisciplinary study discusses the findings of social interaction and social simulation using understandable global examples. Shows the reader how to acquire intercultural data, illustrating each step with descriptive comments and program code.

  12. Multiscale GasKinetics/Particle (MGP) Simulation for Rocket Plume/Lunar Dust Interactions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A Multiscale GasKinetic/Particle (MGP) computational method is proposed to simulate the plume-crater-interaction/dust-impingement(PCIDI) problem. The MGP method...

  13. MHD Simulations of Magnetospheric Accretion, Ejection and Plasma-field Interaction

    Directory of Open Access Journals (Sweden)

    Romanova M. M.

    2014-01-01

    Full Text Available We review recent axisymmetric and three-dimensional (3D magnetohydrodynamic (MHD numerical simulations of magnetospheric accretion, plasma-field interaction and outflows from the disk-magnetosphere boundary.

  14. GPU-Accelerated PIC/MCC Simulation of Laser-Plasma Interaction Using BUMBLEBEE

    Science.gov (United States)

    Jin, Xiaolin; Huang, Tao; Chen, Wenlong; Wu, Huidong; Tang, Maowen; Li, Bin

    2015-11-01

    The research of laser-plasma interaction in its wide applications relies on the use of advanced numerical simulation tools to achieve high performance operation while reducing computational time and cost. BUMBLEBEE has been developed to be a fast simulation tool used in the research of laser-plasma interactions. BUMBLEBEE uses a 1D3V electromagnetic PIC/MCC algorithm that is accelerated by using high performance Graphics Processing Unit (GPU) hardware. BUMBLEBEE includes a friendly user-interface module and four physics simulators. The user-interface provides a powerful solid-modeling front end and graphical and computational post processing functionality. The solver of BUMBLEBEE has four modules for now, which are used to simulate the field ionization, electron collisional ionization, binary coulomb collision and laser-plasma interaction processes. The ionization characteristics of laser-neutral interaction and the generation of high-energy electrons have been analyzed by using BUMBLEBEE for validation.

  15. Finite element simulation of influences of grain interaction on rolling textures of fcc metals

    Institute of Scientific and Technical Information of China (English)

    TANG Jian-guo; ZHANG Xin-ming; CHEN Zhi-yong; DENG Yun-lai

    2006-01-01

    A rate dependent crystal plasticity constitutive model considering self and latent hardening in finite element analysis was developed to simulate rolling textures of pure aluminum. By changing the assignment of orientations to finite elements, i.e. assigning the same set of orientations to all elements or different orientations to different elements, the influences of grain interaction on the formation of rolling textures were numerically simulated with this kind of crystal plasticity finite element model. The simulation results reveal that the grains without considering grain interaction rotate faster than those considering grain interaction, and the rotation of grain boundary is slowed down due to the grain interaction. For a good simulation more elements should be assigned to one grain, in which the effects of both the boundary and interior parts of grain contribute to the formation of rolling textures.

  16. Process monitoring and simulation code verification using interactive computer animation

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, J.N.; Beelman, R.J.; Schwieder, D.H.; Stewart, H.D.

    1984-05-23

    At the Idaho National Engineering Laboratory (INEL), EG and G Idaho, Inc., has developed techniques by which schematics, created for and displayed at color graphics terminals, can be driven by actual or calculated data. These input data cause changes to occur within the displayed schematic. This research is presently being done to develop a prototype to be used in nuclear power plant control rooms. Work stations have already been developed to analyze data that are produced during actual and simulated nuclear reactor experiments.

  17. 3D simulations of gyrosynchrotron emission from mildly anisotropic nonuniform electron distributions in symmetric magnetic loops

    CERN Document Server

    Kuznetsov, Alexey A; Fleishman, Gregory D

    2011-01-01

    Microwave emission of solar flares is formed primarily by incoherent gyrosynchrotron radiation generated by accelerated electrons in coronal magnetic loops. The resulting emission depends on many factors, including pitch-angle distribution of the emitting electrons and the source geometry. In this work, we perform systematic simulations of solar microwave emission using recently developed tools (GS Simulator and fast gyrosynchrotron codes) capable of simulating maps of radio brightness and polarization as well as spatially resolved emission spectra. A 3D model of a symmetric dipole magnetic loop is used. We compare the emission from isotropic and anisotropic (of loss-cone type) electron distributions. We also investigate effects caused by inhomogeneous distribution of the emitting particles along the loop. It is found that effect of the adopted moderate electron anisotropy is the most pronounced near the footpoints and it also depends strongly on the loop orientation. Concentration of the emitting particles a...

  18. Speed Spatial Distribution Models for Traffic Accident Section of Freeway Based on Computer Simulation

    Institute of Scientific and Technical Information of China (English)

    Decai Li; Jiangwei Chu; Wenhui Zhang; Xiaojuan Wang; Guosheng Zhang

    2015-01-01

    Simulation models for accident section on freeway are built in microscopic traffic flow simulation environment. In these models involving 2⁃lane, 3⁃lane and 4⁃lane freeway, one detector is set every 10 m to measure section running speed. According to the simulation results, speed spatial distribution curves for traffic accident section on freeway are drawn which help to determine dangerous sections on upstream of accident section. Furthermore, the speed spatial distribution models are obtained for every speed distribution curve. The results provide theoretical basis for determination on temporal and spatial influence ranges of traffic accident and offer reference to formulation of speed limit scheme and other management measures.

  19. Simulating shock-bubble interactions at water-gelatin interfaces

    Science.gov (United States)

    Adami, Stefan; Kaiser, Jakob; Bermejo-Moreno, Ivan; Adams, Nikolaus

    2016-11-01

    Biomedical problems are often driven by fluid dynamics, as in vivo organisms are usually composed of or filled with fluids that (strongly) affected their physics. Additionally, fluid dynamical effects can be used to enhance certain phenomena or destroy organisms. As examples, we highlight the benign potential of shockwave-driven kidney-stone lithotripsy or sonoporation (acoustic cavitation of microbubbles) to improve drug delivery into cells. During the CTR SummerProgram 2016 we have performed axisymmetric three-phase simulations of a shock hitting a gas bubble in water near a gelatin interface mimicking the fundamental process during sonoporation. We used our multi-resolution finite volume method with sharp interface representation (level-set), WENO-5 shock capturing and interface scale-separation and compared the results with a diffuse-interface method. Qualitatively our simulation results agree well with the reference. Due to the interface treatment the pressure profiles are sharper in our simulations and bubble collapse dynamics are predicted at shorter time-scales. Validation with free-field collapse (Rayleigh collapse) shows very good agreement. The project leading to this application has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No 667483).

  20. Grand Canonical Ensemble Monte Carlo Simulation of Depletion Interactions in Colloidal Suspensions

    Institute of Scientific and Technical Information of China (English)

    GUO Ji-Yuan; XIAO Chang-Ming

    2008-01-01

    Depletion interactions in colloidal suspensions confined between two parallel plates are investigated by using acceptance ratio method with grand canonical ensemble Monte Carlo simulation.The numerical results show that both the depletion potential and depletion force are affected by the confinement from the two parallel plates.Furthermore,it is found that in the grand canonical ensemble Monte Carlo simulation,the depletion interactions are strongly affected by the generalized chemical potential.

  1. A multimodal architecture for simulating natural interactive walking in virtual environments

    OpenAIRE

    Nordahl, Rolf; Serafin, Stefania; Turchet, Luca; Nilsson, Niels Christian

    2011-01-01

    We describe a multimodal system that exploits the use of footwear-based interaction in virtual environments. We developed a pair of shoes enhanced with pressure sensors, actuators, and markers. These shoes control a multichannel surround sound system and drive a physically based audio-haptic synthesis engine that simulates the act of walking on different surfaces. We present the system in all its components, and explain its ability to simulate natural interactive walking in virtual environmen...

  2. Enhancing student learning of two-level quantum systems with interactive simulations

    CERN Document Server

    Kohnle, Antje; Campbell, Anna; Korolkova, Natalia; Paetkau, Mark J

    2015-01-01

    The QuVis Quantum Mechanics Visualization project aims to address challenges of quantum mechanics instruction through the development of interactive simulations for the learning and teaching of quantum mechanics. In this article, we describe evaluation of simulations focusing on two-level systems developed as part of the Institute of Physics Quantum Physics resources. Simulations are research-based and have been iteratively refined using student feedback in individual observation sessions and in-class trials. We give evidence that these simulations are helping students learn quantum mechanics concepts at both the introductory and advanced undergraduate level, and that students perceive simulations to be beneficial to their learning.

  3. Simulation of a pulsatile total artificial heart: Development of a partitioned Fluid Structure Interaction model

    Science.gov (United States)

    Sonntag, Simon J.; Kaufmann, Tim A. S.; Büsen, Martin R.; Laumen, Marco; Linde, Torsten; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2013-04-01

    Heart disease is one of the leading causes of death in the world. Due to a shortage in donor organs artificial hearts can be a bridge to transplantation or even serve as a destination therapy for patients with terminal heart insufficiency. A pusher plate driven pulsatile membrane pump, the Total Artificial Heart (TAH) ReinHeart, is currently under development at the Institute of Applied Medical Engineering of RWTH Aachen University.This paper presents the methodology of a fully coupled three-dimensional time-dependent Fluid Structure Interaction (FSI) simulation of the TAH using a commercial partitioned block-Gauss-Seidel coupling package. Partitioned coupling of the incompressible fluid with the slender flexible membrane as well as a high fluid/structure density ratio of about unity led inherently to a deterioration of the stability (‘artificial added mass instability’). The objective was to conduct a stable simulation with high accuracy of the pumping process. In order to achieve stability, a combined resistance and pressure outlet boundary condition as well as the interface artificial compressibility method was applied. An analysis of the contact algorithm and turbulence condition is presented. Independence tests are performed for the structural and the fluid mesh, the time step size and the number of pulse cycles. Because of the large deformation of the fluid domain, a variable mesh stiffness depending on certain mesh properties was specified for the fluid elements. Adaptive remeshing was avoided. Different approaches for the mesh stiffness function are compared with respect to convergence, preservation of mesh topology and mesh quality. The resulting mesh aspect ratios, mesh expansion factors and mesh orthogonalities are evaluated in detail. The membrane motion and flow distribution of the coupled simulations are compared with a top-view recording and stereo Particle Image Velocimetry (PIV) measurements, respectively, of the actual pump.

  4. Improving the efficiency of the loop method for the simulation of water distribution networks

    OpenAIRE

    2015-01-01

    Efficiency of hydraulic solvers for the simulation of flows and pressures in water distribution systems (WDSs) is very important, especially in the context of optimization and risk analysis problems, where the hydraulic simulation has to be repeated many times. Among the methods used for hydraulic solvers, the most prominent nowadays is the global gradient algorithm (GGA), based on a hybrid node-loop formulation. Previously, another method based just on loop flow equations was proposed, which...

  5. Contribution of static and dynamic load balancing in a real-time distributed air defence simulation

    CSIR Research Space (South Africa)

    Duvenhage, B

    2008-05-01

    Full Text Available and Dynamic Load Balancing In A Real-Time Distributed Air Defence Simulation Mr Bernardt Duvenhage; Mr Jan J. Nel Council for Scientific and Industrial Research (CSIR) bduvenhage@csir.co.za, cnel@csir.co.za Abstract. Simulations with a large number... system. The measure to which dynamic load balancing could further enhance the performance is then explored. Such knowledge forms the basis for further load balance research. 1. INTRODUCTION The South African Council for Scientific and Industrial...

  6. Turbulence radiation interaction modeling in hydrocarbon pool fire simulations

    Energy Technology Data Exchange (ETDEWEB)

    BURNS,SHAWN P.

    1999-12-01

    The importance of turbulent fluctuations in temperature and species concentration in thermal radiation transport modeling for combustion applications is well accepted by the radiation transport and combustion communities. A number of experimental and theoretical studies over the last twenty years have shown that fluctuations in the temperature and species concentrations may increase the effective emittance of a turbulent flame by as much as 50% to 300% over the value that would be expected from the mean temperatures and concentrations. With the possibility of such a large effect on the principal mode of heat transfer from a fire, it is extremely important for fire modeling efforts that turbulence radiation interaction be well characterized and possible modeling approaches understood. Toward this end, this report seeks to accomplish three goals. First, the principal turbulence radiation interaction closure terms are defined. Second, an order of magnitude analysis is performed to understand the relative importance of the various closure terms. Finally, the state of the art in turbulence radiation interaction closure modeling is reviewed. Hydrocarbon pool fire applications are of particular interest in this report and this is the perspective from which this review proceeds. Experimental and theoretical analysis suggests that, for this type of heavily sooting flame, the turbulent radiation interaction effect is dominated by the nonlinear dependence of the Planck function on the temperature. Additional effects due to the correlation between turbulent fluctuations in the absorptivity and temperature may be small relative to the Planck function effect for heavily sooting flames. This observation is drawn from a number of experimental and theoretical discussions. Nevertheless, additional analysis and data is needed to validate this observation for heavily sooting buoyancy dominated plumes.

  7. Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels

    Science.gov (United States)

    Yun, Di; Yacout, Abdellatif M.; Stan, Marius; Bauer, Theodore H.; Wright, Arthur E.

    2014-05-01

    Evolution of porosity generated in metallic U-Zr fuel irradiated in fast spectrum reactors leads to changes in fuel properties and impacts important phenomena such as heat transport and constituent redistribution. The porosity is generated as a result of the accumulation of fission gases and is affected by the possible bond sodium infiltration into the fuel. Typically, the impact of porosity development on properties, such as thermal conductivity, is accounted for through empirical correlations that are dependent on porosity and infiltrated sodium fractions. Currently available simulation tools make it possible to take into account fuel 3-D porosity distributions, potentially eliminating the need for such correlations. This development allows for a more realistic representation of the porosity evolution in metallic fuel and creates a framework for truly mechanistic fuel development models. In this work, COMSOL multi-physics simulation platform is used to model 3-D porosity distributions and simulate heat transport in metallic U-10Zr fuel. Available experimental data regarding microstructural evolution of fuel that was irradiated in EBR-II and associated phase stability information are used to guide the simulation. The impact of changes in porosity characteristics on material properties is estimated and the results are compared with calculated temperature distributions. The simulations demonstrate the developed capability and importance of accounting for detailed porosity distribution features for accurate fuel performance evaluation.

  8. Terrace-width distributions of touching steps: Modification of the fermion analogy with implications for measuring step-step interactions

    Science.gov (United States)

    Sathiyanarayanan, Rajesh; Hamouda, Ajmi Bh.; Einstein, T. L.

    2009-10-01

    Using Monte Carlo simulations, we compute the terrace-width distributions (TWDs) of surfaces in which steps can touch each other, forming multiple-atomic height steps, but cannot cross (no overhangs), and so inconsistent with the standard mapping to spinless fermions. Our results show that the generalized Wigner distribution with minor modifications at small step separations, gives a very good fit for TWDs of touching steps. The interaction strength derived from the fit parameter (ϱ) indicates an effective attraction between steps. The strength of this effective attraction decreases for larger mean-step separations and decreasing step-touching energies; describable via finite-size scaling. Hence, accurate extraction of the true repulsion strength requires multiple vicinalities.

  9. Distribution of Action Potential Duration and T-wave Morphology: a Simulation Study

    CERN Document Server

    Ryzhii, Elena; Wei, Daming

    2009-01-01

    The results of a simulation study of the action potential duration (APD) distribution and T-wave morphology taking into account the midmyocardial cells (M-cells) concept are described. To investigate the effect of M-cells we present a computer model in which ion channel action potential formulations are incorporated into three-dimensional whole heart model. We implemented inhomogeneous continuous action potential duration distribution based on different distributions of maximal slow delayed rectifier current conductance. Using the proposed action potential distribution procedure midmural zeniths with longest action potential length were created as islands of model cells in the depth of thickest areas of ventricular tissue. Different spatial functions on layer indexes were simulated and their influences on electrocardiogram waveforms were analyzed. Changing parameters of ion channel model we varied duration of minimal and maximal action potential and investigated T-wave amplitude, Q-Tpeak and QT intervals vari...

  10. A Two-layer Model for the Simulation of the VARTM Process with Resin Distribution Layer

    Science.gov (United States)

    Young, Wen-Bin

    2013-12-01

    Vacuum assisted resin transfer molding (VARTM) is one of the important processes to fabricate high performance composites. In this process, resin is drawn into the mold to impregnate the fiber reinforcement to a form composite. A resin distribution layer with high permeability was often introduced on top of the fiber reinforcement to accelerate the filling speed. Due to the difference of the flow resistance in the resin distribution layer and the reinforcement as well as the resulting through thickness transverse flow, the filling flow field is intrinsically three-dimensional. This study developed a two-layer model with two-dimensional formulation to simulate the filling flow of the VARTM process with a resin distribution layer. Two-dimensional flow was considered in each layer and a transverse flow in the thickness direction was estimated between the two layers. Thermal analysis including the transverse convection was also performed to better simulate the temperature distribution.

  11. A Computer Simulation of the Interaction of Drugs with Cardiovascular Reflexes.

    Science.gov (United States)

    Walker, J. R.; Traber, D. L.

    1985-01-01

    Discusses advantages and disadvantages of using computer simulations (including those involving application of mathematical models) in teaching physiology and pharmacology, indicating that the major benefit is in performing experiments that cannot be performed in the laboratory. Also considers a simulation on the interaction of drugs with…

  12. Interactive Computer Assisted Instruction in Teaching of Process Analysis and Simulation.

    Science.gov (United States)

    Nuttall, Herbert E., Jr.; Himmelblau, David M.

    To improve the instructional process, time shared computer-assisted instructional methods were developed to teach upper division undergraduate chemical engineering students the concepts of process simulation and analysis. The interactive computer simulation aimed at enabling the student to learn the difficult concepts of process dynamics by…

  13. Driving engineering of novel antimicrobial peptides from simulations of peptide-micelle interactions

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Langham, Allison A; Kaznessis, Yiannis N

    2006-01-01

    peptides and their interaction with membrane mimics. In this article, we discuss the promise and the challenges of widely used models and detail our recent work on peptide-micelle simulations as an attractive alternative to peptide-bilayer simulations. We detail our results with two large structural...

  14. Design and Application of Interactive Simulations in Problem-Solving in University-Level Physics Education

    Science.gov (United States)

    Ceberio, Mikel; Almudí, José Manuel; Franco, Ángel

    2016-01-01

    In recent years, interactive computer simulations have been progressively integrated in the teaching of the sciences and have contributed significant improvements in the teaching-learning process. Practicing problem-solving is a key factor in science and engineering education. The aim of this study was to design simulation-based problem-solving…

  15. Science Laboratory Depth of Learning: Interactive Multimedia Simulation and Virtual Dissection Software

    Science.gov (United States)

    Yuza, Steve C.

    2010-01-01

    The purpose of this study was to determine the effects of interactive multimedia simulations and virtual dissection software on depth of learning among students participating in biology and chemistry laboratory courses. By understanding more about how simulation and virtual dissection software changes depth of learning, educators will have the…

  16. Modeling the Effects of Solar Cell Attitude Distribution on Optical Cross Section for Solar Panel Simulations

    Science.gov (United States)

    Feirstine, K.; Bush, K.; Crosher, C.; Klein, M.; Bowers, D.; Wellems, D.; Duggin, M.; Vaughn, L.

    2012-09-01

    The Air Force Research Laboratory (AFRL) Time-domain Analysis Simulation for Advanced Tracking (TASAT) was used to explore the variation of Optical Cross Section (OCS) with glint angle for a solar panel with different solar cell attitude distribution statistics. Simulations were conducted using a 3D model of a solar panel with various solar cell tip and tilt distribution statistics. Modeling a solar panel as a single sheet of "solar cell" material is not appropriate for OCS glint studies. However, modeling each individual solar cell on the panel, the tips and tilts of which come from a distribution of specified statistics (distribution type, mean, and standard deviation), accurately captures the solar panel OCS with glint angle. The objective of the simulations was to vary the glint measurement angle about the maximum glint position of the solar panel and observe the variations in OCS with angle for a bi-static illumination condition. OCS was calculated relative to the simulated scattering of a Spectralon material in the glint orientation. Results show the importance of solar cell attitude distribution statistics in modeling the OCS observed for a solar panel.

  17. Artificial neural networks for simulating wind effects on sprinkler distribution patterns

    Energy Technology Data Exchange (ETDEWEB)

    Sayyadi, H.; Sadraddini, A. A.; Farsadi Zadeh, D.; Montero, J.

    2012-07-01

    A new approach based on Artificial Neural Networks (ANNs) is presented to simulate the effects of wind on the distribution pattern of a single sprinkler under a center pivot or block irrigation system. Field experiments were performed under various wind conditions (speed and direction). An experimental data from different distribution patterns using a Nelson R3000 Rotator sprinkler have been split into three and used for model training, validation and testing. Parameters affecting the distribution pattern were defined. To find an optimal structure, various networks with different architectures have been trained using an Early Stopping method. The selected structure produced R2 0.929 and RMSE = 6.69 mL for the test subset, consisting of a Multi-Layer Perceptron (MLP) neural network with a backpropagation training algorithm; two hidden layers (twenty neurons in the first hidden layer and six neurons in the second hidden layer) and a tangent-sigmoid transfer function. This optimal network was implemented in MATLAB to develop a model termed ISSP (Intelligent Simulator of Sprinkler Pattern). ISSP uses wind speed and direction as input variables and is able to simulate the distorted distribution pattern from a R3000 Rotator sprinkler with reasonable accuracy (R{sup 2} > 0.935). Results of model evaluation confirm the accuracy and robustness of ANNs for simulation of a single sprinkler distribution pattern under real field conditions. (Author) 41 refs.

  18. Quantum Simulation of Pairing Hamiltonians with Nearest-Neighbor Interacting Qubits

    OpenAIRE

    Wang, Zhixin; Gu, Xiu; Wu, Lian-Ao; Liu, Yu-xi

    2014-01-01

    Although a universal quantum computer is still far from reach, the tremendous advances in controllable quantum devices, in particular with solid-state systems, make it possible to physically implement "quantum simulators". Quantum simulators are physical setups able to simulate other quantum systems efficiently that are intractable on classical computers. Based on solid-state qubit systems with various types of nearest-neighbor interactions, we propose a complete set of algorithms for simulat...

  19. Study on Simulating Spatial Distribution and Varying Patterns of Urumqi's Population

    Institute of Scientific and Technical Information of China (English)

    Chen Xuegang; Yang Zhaoping; Zhang Xiaolei

    2007-01-01

    In this paper,an approach to simulate the spatial distribution of urban population is proposed using urban land use and population statistical data through the geographical information systems(GIS).Then,the spatial population distribution of Urumqi as a case is simulated by the approach mentioned above and its varying patterns are analyzed by the raster population surface.As a result,producing raster population surface is more accurate and natural than the traditional choropleth map of population density.Concerning the spatial population distribution of Urumqi,the population density declines from south to north and the population distribution mainly presents"T-type",the population distribution presents multi-centre agglomeration and the population distribution of the districts shows different features.The population density varies significantly with the incmase in the distance from central business district(CBD).Finally,it is found in this paper that the development history of districts,terrain and traffic road are main factors that have an influence Urumqi's population distribution.This paper tries to provide more accurate population data for the plan and management of urban land,traffic and public facilities in order to enrich the researches on urban population distribution.

  20. Numerical simulation of the fluid-structure interaction between air blast waves and soil structure

    Science.gov (United States)

    Umar, S.; Risby, M. S.; Albert, A. Luthfi; Norazman, M.; Ariffin, I.; Alias, Y. Muhamad

    2014-03-01

    Normally, an explosion threat on free field especially from high explosives is very dangerous due to the ground shocks generated that have high impulsive load. Nowadays, explosion threats do not only occur in the battlefield, but also in industries and urban areas. In industries such as oil and gas, explosion threats may occur on logistic transportation, maintenance, production, and distribution pipeline that are located underground to supply crude oil. Therefore, the appropriate blast resistances are a priority requirement that can be obtained through an assessment on the structural response, material strength and impact pattern of material due to ground shock. A highly impulsive load from ground shocks is a dynamic load due to its loading time which is faster than ground response time. Of late, almost all blast studies consider and analyze the ground shock in the fluid-structure interaction (FSI) because of its influence on the propagation and interaction of ground shock. Furthermore, analysis in the FSI integrates action of ground shock and reaction of ground on calculations of velocity, pressure and force. Therefore, this integration of the FSI has the capability to deliver the ground shock analysis on simulation to be closer to experimental investigation results. In this study, the FSI was implemented on AUTODYN computer code by using Euler-Godunov and the arbitrary Lagrangian-Eulerian (ALE). Euler-Godunov has the capability to deliver a structural computation on a 3D analysis, while ALE delivers an arbitrary calculation that is appropriate for a FSI analysis. In addition, ALE scheme delivers fine approach on little deformation analysis with an arbitrary motion, while the Euler-Godunov scheme delivers fine approach on a large deformation analysis. An integrated scheme based on Euler-Godunov and the arbitrary Lagrangian-Eulerian allows us to analyze the blast propagation waves and structural interaction simultaneously.