WorldWideScience

Sample records for collaborative simulation grid

  1. 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.

  2. Experience with Large Scale Simulations on the EGEE Grid for the AUGER collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Schovancova, J.; Chudoba, J.; Dvorak, F.; Filipovic, J.; Kmunicek, J.; Krenek, A.; Matyska, L.; Mulac, M.; Ruda, M.; Salvet, Z.; Sitera, J.; Sustr, Z.; Travnicek, P.

    2007-07-01

    We share our experience with the Large Scale Monte Carlo Simulations using the CORSIKA simulation program performed by the VO AUGER users on the EGEE Grid environment. We report on the AUGER CPU Challenge performed in April 2007 as a test of availability of the VO AUGER dedicated resources. We developed a set of scripts for an easy handling of a Large Scale Simulations by a very small number of users. We show status of the AUGER Offline Production ran with the CORSIKA simulation program, where these scripts were used. We report our preliminary results with testing the Job Provenance as the long-term information storage. (Author)

  3. The LHCb Grid Simulation

    CERN Multimedia

    Baranov, Alexander

    2016-01-01

    The LHCb Grid access if based on the LHCbDirac system. It provides access to data and computational resources to researchers with different geographical locations. The Grid has a hierarchical topology with multiple sites distributed over the world. The sites differ from each other by their number of CPUs, amount of disk storage and connection bandwidth. These parameters are essential for the Grid work. Moreover, job scheduling and data distribution strategy have a great impact on the grid performance. However, it is hard to choose an appropriate algorithm and strategies as they need a lot of time to be tested on the real grid. In this study, we describe the LHCb Grid simulator. The simulator reproduces the LHCb Grid structure with its sites and their number of CPUs, amount of disk storage and bandwidth connection. We demonstrate how well the simulator reproduces the grid work, show its advantages and limitations. We show how well the simulator reproduces job scheduling and network anomalies, consider methods ...

  4. NREL and DONG Energy Collaboration for Grid Simulator Controls and Testing: Cooperative Research and Development Final Report, CRADA Number CRD-13-527

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-05-01

    The National Renewable Energy Laboratory (NREL) and DONG Energy are interested in collaborating for the development of control algorithms, modeling, and grid simulator testing of wind turbine generator systems involving NWTC's advanced Controllable Grid Interface (CGI). NREL and DONG Energy will work together to develop control algorithms, models, test methods, and protocols involving NREL's CGI, as well as appropriate data acquisition systems for grid simulation testing. The CRADA also includes work on joint publication of results achieved from modeling and testing efforts. Further, DONG Energy will send staff to NREL on a long-term basis for collaborative work including modeling and testing. NREL will send staff to DONG Energy on a short-term basis to visit wind power sites and participate in meetings relevant to this collaborative effort. DOE has provided NREL with over 10 years of support in developing custom facilities and capabilities to enable testing of full-scale integrated wind turbine drivetrain systems in accordance with the needs of the US wind industry. NREL currently operates a 2.5MW dynamometer and is in the processes of commissioning a 5MW dynamometer and a grid simulator (referred to as a 'Controllable Grid Interface' or CGI). DONG Energy is the market leader in offshore wind power development, with currently over 1 GW of on- and offshore wind power in operation, and 1.3 GW under construction. DONG Energy has on-going R&D projects involving high voltage DC (HVDC) transmission.

  5. Polymorphic collaboration in the global grid

    Science.gov (United States)

    McQuay, William K.

    2006-05-01

    Next generation collaborative systems must be able to represent the same information in different forms on a broad spectrum of devices and resources from low end personal digital assistants (PDA) to high performance computers (HPC). Users might be on a desktop then switch to a laptop and then to a PDA while accessing the global grid. The user preference profile for a collaboration session should be capable of moving with them as well as be automatically adjusted for the device type. Collaborative systems must be capable of representing the same information in many forms for different domains and on many devices and thus be polymorphic. Polymorphic collaboration will provide an ability for multiple heterogeneous resources (human to human, human to machine and machine to machine) to share information and activities, as well as the ability to regulate collaborative sessions based on client characteristics and needs; reuse user profiles, tool category choices, and settings in future collaboration session by same or different users; use intelligent agents to assist collaborative systems in learning user/resource preferences and behaviors, and autonomously derive optimal information to provide to users and decision makers. This paper discusses ongoing research in next generation collaborative environments with the goal of making electronic collaboration as easy to use as the telephone - collaboration at the touch of the screen.

  6. Collaborating CPU and GPU for large-scale high-order CFD simulations with complex grids on the TianHe-1A supercomputer

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chuanfu, E-mail: xuchuanfu@nudt.edu.cn [College of Computer Science, National University of Defense Technology, Changsha 410073 (China); Deng, Xiaogang; Zhang, Lilun [College of Computer Science, National University of Defense Technology, Changsha 410073 (China); Fang, Jianbin [Parallel and Distributed Systems Group, Delft University of Technology, Delft 2628CD (Netherlands); Wang, Guangxue; Jiang, Yi [State Key Laboratory of Aerodynamics, P.O. Box 211, Mianyang 621000 (China); Cao, Wei; Che, Yonggang; Wang, Yongxian; Wang, Zhenghua; Liu, Wei; Cheng, Xinghua [College of Computer Science, National University of Defense Technology, Changsha 410073 (China)

    2014-12-01

    Programming and optimizing complex, real-world CFD codes on current many-core accelerated HPC systems is very challenging, especially when collaborating CPUs and accelerators to fully tap the potential of heterogeneous systems. In this paper, with a tri-level hybrid and heterogeneous programming model using MPI + OpenMP + CUDA, we port and optimize our high-order multi-block structured CFD software HOSTA on the GPU-accelerated TianHe-1A supercomputer. HOSTA adopts two self-developed high-order compact definite difference schemes WCNS and HDCS that can simulate flows with complex geometries. We present a dual-level parallelization scheme for efficient multi-block computation on GPUs and perform particular kernel optimizations for high-order CFD schemes. The GPU-only approach achieves a speedup of about 1.3 when comparing one Tesla M2050 GPU with two Xeon X5670 CPUs. To achieve a greater speedup, we collaborate CPU and GPU for HOSTA instead of using a naive GPU-only approach. We present a novel scheme to balance the loads between the store-poor GPU and the store-rich CPU. Taking CPU and GPU load balance into account, we improve the maximum simulation problem size per TianHe-1A node for HOSTA by 2.3×, meanwhile the collaborative approach can improve the performance by around 45% compared to the GPU-only approach. Further, to scale HOSTA on TianHe-1A, we propose a gather/scatter optimization to minimize PCI-e data transfer times for ghost and singularity data of 3D grid blocks, and overlap the collaborative computation and communication as far as possible using some advanced CUDA and MPI features. Scalability tests show that HOSTA can achieve a parallel efficiency of above 60% on 1024 TianHe-1A nodes. With our method, we have successfully simulated an EET high-lift airfoil configuration containing 800M cells and China's large civil airplane configuration containing 150M cells. To our best knowledge, those are the largest-scale CPU–GPU collaborative simulations

  7. Cosmological Simulations using Grid Middleware

    CERN Document Server

    Caniou, Y; Depardon, B; Courtois, H; Teyssier, R

    2006-01-01

    One way to access the aggregated power of a collection of heterogeneous machines is to use a grid middleware, such as DIET, GridSolve or NINF. It addresses the problem of monitoring the resources, of handling the submissions of jobs and as an example the inherent transfer of input and output data, in place of the user. In this paper we present how to run cosmological simulations using the RAMSES application along with the DIET middleware. We will describe how to write the corresponding DIET client and server. The remainder of the paper is organized as follows: Section 2 presents the DIET middleware. Section 3 describes the RAMSES cosmological software and simulations, and how to interface it with DIET. We show how to write a client and a server in Section 4. Finally, Section 5 presents the experiments realized on Grid'5000, the French Research Grid, and we conclude in Section 6.

  8. Grid computing and biomolecular simulation.

    Science.gov (United States)

    Woods, Christopher J; Ng, Muan Hong; Johnston, Steven; Murdock, Stuart E; Wu, Bing; Tai, Kaihsu; Fangohr, Hans; Jeffreys, Paul; Cox, Simon; Frey, Jeremy G; Sansom, Mark S P; Essex, Jonathan W

    2005-08-15

    Biomolecular computer simulations are now widely used not only in an academic setting to understand the fundamental role of molecular dynamics on biological function, but also in the industrial context to assist in drug design. In this paper, two applications of Grid computing to this area will be outlined. The first, involving the coupling of distributed computing resources to dedicated Beowulf clusters, is targeted at simulating protein conformational change using the Replica Exchange methodology. In the second, the rationale and design of a database of biomolecular simulation trajectories is described. Both applications illustrate the increasingly important role modern computational methods are playing in the life sciences.

  9. Scalable Open Source Smart Grid Simulator (SGSim)

    DEFF Research Database (Denmark)

    Ebeid, Emad Samuel Malki; Jacobsen, Rune Hylsberg; Quaglia, Davide

    2017-01-01

    . This paper presents an open source smart grid simulator (SGSim). The simulator is based on open source SystemC Network Simulation Library (SCNSL) and aims to model scalable smart grid applications. SGSim has been tested under different smart grid scenarios that contain hundreds of thousands of households...

  10. Collaborative DFA learning applied to Grid administration

    NARCIS (Netherlands)

    Mulder, W.; Jacobs, C.J.H.; van Someren, M.; van Erp, M.; Stehouwer, H.; van Zaanen, M.

    2009-01-01

    This paper proposes a distributed learning mechanism that learns patterns from distributed datasets. The complex and dynamic settings of grid environments requires supporting systems to be of a more sophisticated level. Contemporary tools lack the ability to relate and infer events. We developed an

  11. Collaborative DFA learning applied to Grid administration

    NARCIS (Netherlands)

    W. Mulder; C.J.H. Jacobs; M. van Someren

    2009-01-01

    This paper proposes a distributed learning mechanism that learns patterns from distributed datasets. The complex and dynamic settings of grid environments requires supporting systems to be of a more sophisticated level. Contemporary tools lack the ability to relate and infer events. We developed an

  12. Grid simulator for power quality assessment of micro-grids

    DEFF Research Database (Denmark)

    Carrasco, Joaquin Eloy Garcia; Vasquez, Juan Carlos; Guerrero, Josep M.

    2013-01-01

    In this study, a grid simulator based on a back-to-back inverter topology with resonant controllers is presented. The simulator is able to generate three-phase voltages for a range of amplitudes and frequencies with different types of perturbations, such as voltage sags, steady-state unbalanced v...

  13. MaGate Simulator: A Simulation Environment for a Decentralized Grid Scheduler

    Science.gov (United States)

    Huang, Ye; Brocco, Amos; Courant, Michele; Hirsbrunner, Beat; Kuonen, Pierre

    This paper presents a simulator for of a decentralized modular grid scheduler named MaGate. MaGate’s design emphasizes scheduler interoperability by providing intelligent scheduling serving the grid community as a whole. Each MaGate scheduler instance is able to deal with dynamic scheduling conditions, with continuously arriving grid jobs. Received jobs are either allocated on local resources, or delegated to other MaGates for remote execution. The proposed MaGate simulator is based on GridSim toolkit and Alea simulator, and abstracts the features and behaviors of complex fundamental grid elements, such as grid jobs, grid resources, and grid users. Simulation of scheduling tasks is supported by a grid network overlay simulator executing distributed ant-based swarm intelligence algorithms to provide services such as group communication and resource discovery. For evaluation, a comparison of behaviors of different collaborative policies among a community of MaGates is provided. Results support the use of the proposed approach as a functional ready grid scheduler simulator.

  14. Collaboration in a Wireless Grid Innovation Testbed by Virtual Consortium

    Science.gov (United States)

    Treglia, Joseph; Ramnarine-Rieks, Angela; McKnight, Lee

    This paper describes the formation of the Wireless Grid Innovation Testbed (WGiT) coordinated by a virtual consortium involving academic and non-academic entities. Syracuse University and Virginia Tech are primary university partners with several other academic, government, and corporate partners. Objectives include: 1) coordinating knowledge sharing, 2) defining key parameters for wireless grids network applications, 3) dynamically connecting wired and wireless devices, content and users, 4) linking to VT-CORNET, Virginia Tech Cognitive Radio Network Testbed, 5) forming ad hoc networks or grids of mobile and fixed devices without a dedicated server, 6) deepening understanding of wireless grid application, device, network, user and market behavior through academic, trade and popular publications including online media, 7) identifying policy that may enable evaluated innovations to enter US and international markets and 8) implementation and evaluation of the international virtual collaborative process.

  15. The QuarkNet/Grid collaborative learning e-lab

    Energy Technology Data Exchange (ETDEWEB)

    Bardeen, Marjorie; Gilbert, Eric; Jordan, Thomas; Nepywoda, Paul; Quigg, Elizabeth; /Fermilab; Wilde, Mike; /Argonne; Zhao, Yong; /Chicago U.

    2004-12-01

    We describe a case study that uses grid computing techniques to support the collaborative learning of high school students investigating cosmic rays. Students gather and upload science data to our e-Lab portal. They explore those data using techniques from the GriPhyN collaboration. These techniques include virtual data transformations, workflows, metadata cataloging and indexing, data product provenance and persistence, as well as job planners. Students use web browsers and a custom interface that extends the GriPhyN Chiron portal to perform all of these tasks. They share results in the form of online posters and ask each other questions in this asynchronous environment. Students can discover and extend the research of other students, modeling the processes of modern large-scale scientific collaborations. Also, the e-Lab portal provides tools for teachers to guide student work throughout an investigation.

  16. Data Compression of Hydrocarbon Reservoir Simulation Grids

    KAUST Repository

    Chavez, Gustavo Ivan

    2015-05-28

    A dense volumetric grid coming from an oil/gas reservoir simulation output is translated into a compact representation that supports desired features such as interactive visualization, geometric continuity, color mapping and quad representation. A set of four control curves per layer results from processing the grid data, and a complete set of these 3-dimensional surfaces represents the complete volume data and can map reservoir properties of interest to analysts. The processing results yield a representation of reservoir simulation results which has reduced data storage requirements and permits quick performance interaction between reservoir analysts and the simulation data. The degree of reservoir grid compression can be selected according to the quality required, by adjusting for different thresholds, such as approximation error and level of detail. The processions results are of potential benefit in applications such as interactive rendering, data compression, and in-situ visualization of large-scale oil/gas reservoir simulations.

  17. Computer Simulation of the UMER Gridded Gun

    CERN Document Server

    Haber, Irving; Friedman, Alex; Grote, D P; Kishek, Rami A; Reiser, Martin; Vay, Jean-Luc; Zou, Yun

    2005-01-01

    The electron source in the University of Maryland Electron Ring (UMER) injector employs a grid 0.15 mm from the cathode to control the current waveform. Under nominal operating conditions, the grid voltage during the current pulse is sufficiently positive relative to the cathode potential to form a virtual cathode downstream of the grid. Three-dimensional computer simulations have been performed that use the mesh refinement capability of the WARP particle-in-cell code to examine a small region near the beam center in order to illustrate some of the complexity that can result from such a gridded structure. These simulations have been found to reproduce the hollowed velocity space that is observed experimentally. The simulations also predict a complicated time-dependent response to the waveform applied to the grid during the current turn-on. This complex temporal behavior appears to result directly from the dynamics of the virtual cathode formation and may therefore be representative of the expected behavior in...

  18. Coarse Grid CFD for underresolved simulation

    Science.gov (United States)

    Class, Andreas G.; Viellieber, Mathias O.; Himmel, Steffen R.

    2010-11-01

    CFD simulation of the complete reactor core of a nuclear power plant requires exceedingly huge computational resources so that this crude power approach has not been pursued yet. The traditional approach is 1D subchannel analysis employing calibrated transport models. Coarse grid CFD is an attractive alternative technique based on strongly under-resolved CFD and the inviscid Euler equations. Obviously, using inviscid equations and coarse grids does not resolve all the physics requiring additional volumetric source terms modelling viscosity and other sub-grid effects. The source terms are implemented via correlations derived from fully resolved representative simulations which can be tabulated or computed on the fly. The technique is demonstrated for a Carnot diffusor and a wire-wrap fuel assembly [1]. [4pt] [1] Himmel, S.R. phd thesis, Stuttgart University, Germany 2009, http://bibliothek.fzk.de/zb/berichte/FZKA7468.pdf

  19. Modularized Parallel Neutron Instrument Simulation on the TeraGrid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Meili [ORNL; Cobb, John W [ORNL; Hagen, Mark E [ORNL; Miller, Stephen D [ORNL; Lynch, Vickie E [ORNL

    2007-01-01

    In order to build a bridge between the TeraGrid (TG), a national scale cyberinfrastructure resource, and neutron science, the Neutron Science TeraGrid Gateway (NSTG) is focused on introducing productive HPC usage to the neutron science community, primarily the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Monte Carlo simulations are used as a powerful tool for instrument design and optimization at SNS. One of the successful efforts of a collaboration team composed of NSTG HPC experts and SNS instrument scientists is the development of a software facility named PSoNI, Parallelizing Simulations of Neutron Instruments. Parallelizing the traditional serial instrument simulation on TeraGrid resources, PSoNI quickly computes full instrument simulation at sufficient statistical levels in instrument de-sign. Upon SNS successful commissioning, to the end of 2007, three out of five commissioned instruments in SNS target station will be available for initial users. Advanced instrument study, proposal feasibility evalua-tion, and experiment planning are on the immediate schedule of SNS, which pose further requirements such as flexibility and high runtime efficiency on fast instrument simulation. PSoNI has been redesigned to meet the new challenges and a preliminary version is developed on TeraGrid. This paper explores the motivation and goals of the new design, and the improved software structure. Further, it describes the realized new fea-tures seen from MPI parallelized McStas running high resolution design simulations of the SEQUOIA and BSS instruments at SNS. A discussion regarding future work, which is targeted to do fast simulation for automated experiment adjustment and comparing models to data in analysis, is also presented.

  20. Overview of Simulation Tools for Smart Grids

    DEFF Research Database (Denmark)

    aim of this report “D2.1 – Overview of Simulation Tools for Smart Grids” is to provide an overview of the different simulation tools available, i.e. developed and in use, at the different research centres. Required new tool capabilities are identified and extensions to the existing packages...... are indicated. An analysis of the emerging power systems challenges together with a review of the main topics regarding smart grids is provided in Chapter 1. The requirements for the simulation tools and the list of available tools in the different research centres and their main characteristic are reported...... in Chapter 2. The main aspects of the different tools and their purpose of analysis are listed in Chapter 3 along with the main topics concerning the new requirements for tools in order to allow a proper study in the smart grid context. Gaps capabilities and model consolidation of the analysed tools...

  1. Cosmological Simulations on a Grid of Computers

    CERN Document Server

    Depardon, Benjamin; Desprez, Frédéric; Blaizot, Jérémy; Courtois, Hélène M

    2010-01-01

    The work presented in this paper aims at restricting the input parameter values of the semi-analytical model used in GALICS and MOMAF, so as to derive which parameters influence the most the results, e.g., star formation, feedback and halo recycling efficiencies, etc. Our approach is to proceed empirically: we run lots of simulations and derive the correct ranges of values. The computation time needed is so large, that we need to run on a grid of computers. Hence, we model GALICS and MOMAF execution time and output files size, and run the simulation using a grid middleware: DIET. All the complexity of accessing resources, scheduling simulations and managing data is harnessed by DIET and hidden behind a web portal accessible to the users.

  2. Opportunities for Grid Modernization Collaboration: U.K.-U.S. Grid Modernization Workshop Report, February 28 - March 2, 2017

    Energy Technology Data Exchange (ETDEWEB)

    2017-06-28

    This report captures the discussions and takeaways from the U.K.-U.S. Grid Modernization Workshop on February 28-March 2, 2017 at the National Renewable Energy Laboratory. Speakers from across the United States and Europe convened to discuss the challenges associated with grid modernization for the 21st century, while identifying transatlantic solutions and opportunities for collaboration.

  3. Design and Implementation of a Four-Quadrant Grid Simulator

    Directory of Open Access Journals (Sweden)

    Minhua Qian

    2013-06-01

    Full Text Available This study presents the development of a grid simulator which is capable of generating sinusoidal waveforms with variable amplitude and frequency over a wide range. Moreover, it can achieve four-quadrant operation and allows bi-directional power flow due to the back-to-back topology. The transient grid conditions generated by this grid simulator can comply with the requirements of the international standards, such as VDE-AR-N 4105. So, it is well suited for testing grid-connected photovoltaic inverters. Both simulation and experiment results showed that the grid simulator designed in this study can provide transient grid conditions and achieve four-quadrant operation.

  4. Power grid simulation applications developed using the GridPACK™ high performance computing framework

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Shuangshuang; Chen, Yousu; Diao, Ruisheng; Huang, Zhenyu (Henry); Perkins, William; Palmer, Bruce

    2016-12-01

    This paper describes the GridPACK™ software framework for developing power grid simulations that can run on high performance computing platforms, with several example applications (dynamic simulation, static contingency analysis, and dynamic contingency analysis) that have been developed using GridPACK.

  5. Flexible Residential Smart Grid Simulation Framework

    Science.gov (United States)

    Xiang, Wang

    Different scheduling and coordination algorithms controlling household appliances' operations can potentially lead to energy consumption reduction and/or load balancing in conjunction with different electricity pricing methods used in smart grid programs. In order to easily implement different algorithms and evaluate their efficiency against other ideas, a flexible simulation framework is desirable in both research and business fields. However, such a platform is currently lacking or underdeveloped. In this thesis, we provide a simulation framework to focus on demand side residential energy consumption coordination in response to different pricing methods. This simulation framework, equipped with an appliance consumption library using realistic values, aims to closely represent the average usage of different types of appliances. The simulation results of traditional usage yield close matching values compared to surveyed real life consumption records. Several sample coordination algorithms, pricing schemes, and communication scenarios are also implemented to illustrate the use of the simulation framework.

  6. Petascale Flow Simulations Using Particles and Grids

    Science.gov (United States)

    Koumoutsakos, Petros

    2014-11-01

    How to chose the discretization of flow models in order to harness the power of available computer architectures? Our group explores this question for particle (vortex methods, molecular and dissipative particle dynamics) and grid based (finite difference, finite volume) discretisations for flow simulations across scales. I will discuss methodologies to transition between these methods and their implementation in massively parallel computer architectures. I will present simulations ranging from flows of cells in microfluidic channels to cloud cavitation collapse at 14.5 PFLOP/s. This research was supported by the European Research Council, the Swiss National Science Foundation and the Swiss National Supercomputing Center.

  7. COLLABORATIVE RESEARCH: CONTINUOUS DYNAMIC GRID ADAPTATION IN A GLOBAL ATMOSPHERIC MODEL: APPLICATION AND REFINEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Gutowski, William J.; Prusa, Joseph M.; Smolarkiewicz, Piotr K.

    2012-05-08

    This project had goals of advancing the performance capabilities of the numerical general circulation model EULAG and using it to produce a fully operational atmospheric global climate model (AGCM) that can employ either static or dynamic grid stretching for targeted phenomena. The resulting AGCM combined EULAG's advanced dynamics core with the "physics" of the NCAR Community Atmospheric Model (CAM). Effort discussed below shows how we improved model performance and tested both EULAG and the coupled CAM-EULAG in several ways to demonstrate the grid stretching and ability to simulate very well a wide range of scales, that is, multi-scale capability. We leveraged our effort through interaction with an international EULAG community that has collectively developed new features and applications of EULAG, which we exploited for our own work summarized here. Overall, the work contributed to over 40 peer-reviewed publications and over 70 conference/workshop/seminar presentations, many of them invited. 3a. EULAG Advances EULAG is a non-hydrostatic, parallel computational model for all-scale geophysical flows. EULAG's name derives from its two computational options: EULerian (flux form) or semi-LAGrangian (advective form). The model combines nonoscillatory forward-in-time (NFT) numerical algorithms with a robust elliptic Krylov solver. A signature feature of EULAG is that it is formulated in generalized time-dependent curvilinear coordinates. In particular, this enables grid adaptivity. In total, these features give EULAG novel advantages over many existing dynamical cores. For EULAG itself, numerical advances included refining boundary conditions and filters for optimizing model performance in polar regions. We also added flexibility to the model's underlying formulation, allowing it to work with the pseudo-compressible equation set of Durran in addition to EULAG's standard anelastic formulation. Work in collaboration with others also extended the

  8. 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.

  9. ISOGA: Integrated Services Optical Grid Architecture for Emerging E-Science Collaborative Applications

    Energy Technology Data Exchange (ETDEWEB)

    Oliver Yu

    2008-11-28

    This final report describes the accomplishments in the ISOGA (Integrated Services Optical Grid Architecture) project. ISOGA enables efficient deployment of existing and emerging collaborative grid applications with increasingly diverse multimedia communication requirements over a wide-area multi-domain optical network grid; and enables collaborative scientists with fast retrieval and seamless browsing of distributed scientific multimedia datasets over a wide-area optical network grid. The project focuses on research and development in the following areas: the polymorphic optical network control planes to enable multiple switching and communication services simultaneously; the intelligent optical grid user-network interface to enable user-centric network control and monitoring; and the seamless optical grid dataset browsing interface to enable fast retrieval of local/remote dataset for visualization and manipulation.

  10. Towards a collaborative framework to improve urban grid resilience

    NARCIS (Netherlands)

    Jung, Oliver; Besser, Sandford; Ceccarelli, Andrea; Zoppi, Tomasso; Vasenev, Alexandr; Montoya, Lorena; Clarke, Tony; Chappell, Keith

    2016-01-01

    Two trends will help to ensure reliable electricity supply in Smart Cities: a) the ongoing deployment of Smart Grid technology and b) the adoption of distributed energy resources. Unfortunately, the increased reliance on ICT in the Smart Grid will expose new threats that could result in incidents th

  11. GridLAB-D: An Agent-Based Simulation Framework for Smart Grids

    Directory of Open Access Journals (Sweden)

    David P. Chassin

    2014-01-01

    Full Text Available Simulation of smart grid technologies requires a fundamentally new approach to integrated modeling of power systems, energy markets, building technologies, and the plethora of other resources and assets that are becoming part of modern electricity production, delivery, and consumption systems. As a result, the US Department of Energy’s Office of Electricity commissioned the development of a new type of power system simulation tool called GridLAB-D that uses an agent-based approach to simulating smart grids. This paper presents the numerical methods and approach to time-series simulation used by GridLAB-D and reviews applications in power system studies, market design, building control system design, and integration of wind power in a smart grid.

  12. National power grid simulation capability : need and issues

    Energy Technology Data Exchange (ETDEWEB)

    Petri, Mark C. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2009-06-02

    On December 9 and 10, 2008, the Department of Homeland Security (DHS) Science and Technology Directorate sponsored a national workshop at Argonne National Laboratory to explore the need for a comprehensive modeling and simulation capability for the national electric power grid system. The workshop brought together leading electric power grid experts from federal agencies, the national laboratories, and academia to discuss the current state of power grid science and engineering and to assess if important challenges are being met. The workshop helped delineate gaps between grid needs and current capabilities and identify issues that must be addressed if a solution is to be implemented. This report is a result of the workshop and highlights power grid modeling and simulation needs, the barriers that must be overcome to address them, and the benefits of a national power grid simulation capability.

  13. The Japanese Smart Grid Initiatives, Investments, and Collaborations

    Directory of Open Access Journals (Sweden)

    Mukaidono Masao

    2012-07-01

    Full Text Available A smart grid delivers power around the country and has an intelligent monitoring system, which not only keeps track of all the energy coming in from diverse sources but also can detect where energy is needed through a two-way communication system that collects data about how and when consumers use power. It is safer in many ways, compared with the current one-directional power supply system that seems susceptible to either sabotage or natural disasters, including being more resistant to attack and power outages. In such an autonomic and advanced-grid environment, investing in a pilot study and knowing the nation’s readiness to adopt a smart grid absolves the government of complex intervention from any failure to bring Japan into the autonomic-grid environment. This paper looks closely into the concept of the Japanese government’s ‘go green’ effort, the objective of which is to make Japan a leading nation in environmental and energy sustainability through green innovation, such as creating a low-carbon society and embracing the natural grid community. This paper paints a clearer conceptual picture of how Japan’s smart grid effort compares with that of the US. The structure of Japan’s energy sources is describe including its major power generation plants, photovoltaic power generation development, and a comparison of energy sources between Japan and the US. Japan’s smart community initiatives are also highlighted, illustrating the Japanese government planned social security system, which focuses on a regional energy management system and lifestyle changes under such an energy supply structure. This paper also discusses Japan’s involvement in smart grid pilot projects for development and investment, and its aim of obtaining successful outcomes. Engagement in the pilot projects is undertaken in conjunction with Japan’s attempt to implement a fully smart grid city in the near future. In addition, major smart grid awareness

  14. Constructing a Grid Simulation for E-Governance Applications Using GridSim

    Directory of Open Access Journals (Sweden)

    Mrs. P. Sumathi

    2008-01-01

    Full Text Available This study provides a design framework for the adoption of grid computing for e-governance applications. Problem statement: E-Governance is the application of information and communication technology to achieve efficiency, effectiveness, transparency and accountability in Government to Government (G2G, Government to Employee (G2E, Government to Citizen (G2C and Government to Business (G2B. It enables citizens to make best use of automated administration processes that are accessible on-line. Grid computing is an ideal solution to this type of applications and the study presents how grid computing can be used to effectively and efficiently handle such huge data. In this study, we illustrate the creation of a virtual environment by using existing Grid technologies to specific e-governance applications on distributed resources. Approach: A Grid generally refers to an infrastructure that involves the integrated and collaborative use of all computing resources into a single virtual computing environment. Grid applications often involve large amounts of data and/or computing resources that require secure resource sharing across organizational boundaries. Grid computing is an ideal solution to this type of applications and the study presents how grid computing can be used to effectively and efficiently handle such huge data. Results: The applications were run with the grid environment and without Grid environment. The results obtained were compared with the time and the number of jobs. The obtained results using grid environment were more significant and promising. Conclusions: Implementing an E-Governance solution will lower the cost of developing, deploying, managing government solutions and providing better services to citizens.

  15. COLLABORATIVE RESEARCH: CONTINUOUS DYNAMIC GRID ADAPTATION IN A GLOBAL ATMOSPHERIC MODEL: APPLICATION AND REFINEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Gutowski, William J.; Prusa, Joseph M.; Smolarkiewicz, Piotr K.

    2012-05-08

    This project had goals of advancing the performance capabilities of the numerical general circulation model EULAG and using it to produce a fully operational atmospheric global climate model (AGCM) that can employ either static or dynamic grid stretching for targeted phenomena. The resulting AGCM combined EULAG's advanced dynamics core with the "physics" of the NCAR Community Atmospheric Model (CAM). Effort discussed below shows how we improved model performance and tested both EULAG and the coupled CAM-EULAG in several ways to demonstrate the grid stretching and ability to simulate very well a wide range of scales, that is, multi-scale capability. We leveraged our effort through interaction with an international EULAG community that has collectively developed new features and applications of EULAG, which we exploited for our own work summarized here. Overall, the work contributed to over 40 peer-reviewed publications and over 70 conference/workshop/seminar presentations, many of them invited. 3a. EULAG Advances EULAG is a non-hydrostatic, parallel computational model for all-scale geophysical flows. EULAG's name derives from its two computational options: EULerian (flux form) or semi-LAGrangian (advective form). The model combines nonoscillatory forward-in-time (NFT) numerical algorithms with a robust elliptic Krylov solver. A signature feature of EULAG is that it is formulated in generalized time-dependent curvilinear coordinates. In particular, this enables grid adaptivity. In total, these features give EULAG novel advantages over many existing dynamical cores. For EULAG itself, numerical advances included refining boundary conditions and filters for optimizing model performance in polar regions. We also added flexibility to the model's underlying formulation, allowing it to work with the pseudo-compressible equation set of Durran in addition to EULAG's standard anelastic formulation. Work in collaboration with others also extended the

  16. Measurements and simulations of turbines on common grid

    Science.gov (United States)

    Nielsen, T. K.; Storli, P.-T.

    2014-03-01

    Speed droop control is of basic importance for the primary governing in the Nordic grid. The speed droop control. a mandatory and build-in regulatory loop on all larger units. is automatically changing the produced power on synchronous units as the grid frequency changes. This part of the governor allows a certain deviance from the nominal 50 Hz grid frequency. If the grid frequency is decreasing this means that the load on the grid is greater than the power delivered into the grid. and the local speed droop regulatory loop on each unit then autonomously increases the production to obtain a new balance between load and production. which will be at a lower frequency than 50 Hz. If the power delivered into the grid is greater than the load. the rotating masses will be accelerated (thus increasing the grid frequency) and the speed droop operation will act to reduce the power produced to obtain a new balance. this time at a higher frequency than 50 Hz. The frequency in the Nordic power grid has in recent years for increasing duration been outside the allowed steady state frequency band of 50 ± 0.1 Hz. In order to study the behaviour of a turbine operating on a common grid, measurements have been done at site. The measurements performed are the generator power, main servo motor position, the rotational speed of the unit and the grid frequency. The purpose of the measurements was to see if it is possible to observe the behaviour of the machine as it is linked together with all the other machines on a synchronous grid. It is interesting to observe the response to deviations in the frequency due to the speed droop operation. In order to better understand the behaviour, a simulation model of two power plants, complete with individual conduit system, turbine and generator, connected to the same grid was used.

  17. Use of the Repertory Grid for collaboration and reflection in a research context

    CSIR Research Space (South Africa)

    Alexander, P

    2010-09-01

    Full Text Available for collaboration and reflection in a research context Patricia Alexander1, Johan van Loggerenberg2, Hugo Lotriet3, Jackie Phahlamohlaka4 1,2,3 Department of Informatics, University of Pretoria, Hatfield, PRETORIA, 0083, South Africa Patricia....Alexander@up.ac.za 4 Department of Informatics, University of Pretoria and Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa JPhahlamohlaka@csir.co.za Running head: Repertory Grid for collaboration & reflection ABSTRACT...

  18. Research collaboration and the expanding science grid: Measuring globalization processes worldwide

    CERN Document Server

    Tijssen, Robert J W; van Eck, Nees Jan

    2012-01-01

    This paper applies a new model and analytical tool to measure and study contemporary globalization processes in collaborative science - a world in which scientists, scholars, technicians and engineers interact within a 'grid' of interconnected research sites and collaboration networks. The building blocks of our metrics are the cities where scientific research is conducted, as mentioned in author addresses on research publications. The unit of analysis is the geographical distance between those cities. In our macro-level trend analysis, covering the years 2000-2010, we observe that research collaboration distances have been increasing, while the share of collaborative contacts with foreign cities has leveled off. Collaboration distances and growth rates differ significantly between countries and between fields of science. The application of a distance metrics to compare and track these processes opens avenues for further studies, both at the meso-level and at the micro-level, into how research collaboration p...

  19. SAUNA: A system for grid generation and flow simulation using hybrid structured/unstructured grids

    Science.gov (United States)

    Childs, P. N.; Shaw, J. A.; Peace, A. J.; Georgala, J. M.

    1992-05-01

    The development of a flow simulation facility for predicting the aerodynamics of complex configurations wherein the grid is composed of both structured and unstructured regions is described. Issues relating to the generation and analysis of such grids and to the accurate and efficient computation of both inviscid and viscous flows thereon are considered. Further the development of a comprehensive post-processing and visualization facility is explored. Techniques are illustrated throughout by application to realistic aircraft geometries.

  20. Improving collaboration between primary care research networks using Access Grid technology

    Directory of Open Access Journals (Sweden)

    Zsolt Nagykaldi

    2008-05-01

    Full Text Available Access Grid (AG is an Internet2-driven, high performance audio_visual conferencing technology used worldwide by academic and government organisations to enhance communication, human interaction and group collaboration. AG technology is particularly promising for improving academic multi-centre research collaborations. This manuscript describes how the AG technology was utilised by the electronic Primary Care Research Network (ePCRN that is part of the National Institutes of Health (NIH Roadmap initiative to improve primary care research and collaboration among practice- based research networks (PBRNs in the USA. It discusses the design, installation and use of AG implementations, potential future applications, barriers to adoption, and suggested solutions.

  1. Bioinfogrid:. Bioinformatics Simulation and Modeling Based on Grid

    Science.gov (United States)

    Milanesi, Luciano

    2007-12-01

    Genomics sequencing projects and new technologies applied to molecular genetics analysis are producing huge amounts of raw data. In future the trend of the biomedical scientific research will be based on computing Grids for data crunching applications, data Grids for distributed storage of large amounts of accessible data and the provision of tools to all users. Biomedical research laboratories are moving towards an environment, created through the sharing of resources, in which heterogeneous and dispersed health data, such as molecular data (e.g. genomics, proteomics), cellular data (e.g. pathways), tissue data, population data (e.g. Genotyping, SNP, Epidemiology), as well the data generated by large scale analysis (eg. Simulation data, Modelling). In this paper some applications developed in the framework of the European Project "Bioinformatics Grid Application for life science - BioinfoGRID" will be described in order to show the potentiality of the GRID to carry out large scale analysis and research worldwide.

  2. Towards Hybrid Overset Grid Simulations of the Launch Environment

    Science.gov (United States)

    Moini-Yekta, Shayan

    A hybrid overset grid approach has been developed for the design and analysis of launch vehicles and facilities in the launch environment. The motivation for the hybrid grid methodology is to reduce the turn-around time of computational fluid dynamic simulations and improve the ability to handle complex geometry and flow physics. The LAVA (Launch Ascent and Vehicle Aerodynamics) hybrid overset grid scheme consists of two components: an off-body immersed-boundary Cartesian solver with block-structured adaptive mesh refinement and a near-body unstructured body-fitted solver. Two-way coupling is achieved through overset connectivity between the off-body and near-body grids. This work highlights verification using code-to-code comparisons and validation using experimental data for the individual and hybrid solver. The hybrid overset grid methodology is applied to representative unsteady 2D trench and 3D generic rocket test cases.

  3. Optorsim: A Grid Simulator for Studying Dynamic Data Replication Strategies

    CERN Document Server

    Bell, William H; Millar, A Paul; Capozza, Luigi; Stockinger, Kurt; Zini, Floriano

    2003-01-01

    Computational grids process large, computationally intensive problems on small data sets. In contrast, data grids process large computational problems that in turn require evaluating, mining and producing large amounts of data. Replication, creating geographically disparate identical copies of data, is regarded as one of the major optimization techniques for reducing data access costs. In this paper, several replication algorithms are discussed. These algorithms were studied using the Grid simulator: OptorSim. OptorSim provides a modular framework within which optimization strategies can be studied under different Grid configurations. The goal is to explore the stability and transient behaviour of selected optimization techniques. We detail the design and implementation of OptorSim and analyze various replication algorithms based on different Grid workloads.

  4. Hardware-in-the-loop grid simulator system and method

    Science.gov (United States)

    Fox, John Curtiss; Collins, Edward Randolph; Rigas, Nikolaos

    2017-05-16

    A hardware-in-the-loop (HIL) electrical grid simulation system and method that combines a reactive divider with a variable frequency converter to better mimic and control expected and unexpected parameters in an electrical grid. The invention provides grid simulation in a manner to allow improved testing of variable power generators, such as wind turbines, and their operation once interconnected with an electrical grid in multiple countries. The system further comprises an improved variable fault reactance (reactive divider) capable of providing a variable fault reactance power output to control a voltage profile, therein creating an arbitrary recovery voltage. The system further comprises an improved isolation transformer designed to isolate zero-sequence current from either a primary or secondary winding in a transformer or pass the zero-sequence current from a primary to a secondary winding.

  5. Collaborative virtual experience based on reconfigurable simulation

    Science.gov (United States)

    Shahab, Qonita M.; Kwon, Yong-Moo; Ko, Heedong

    2006-10-01

    Virtual Reality simulation enables immersive 3D experience of a Virtual Environment. A simulation-based Virtual Environment can be used to map real world phenomena onto virtual experience. With a reconfigurable simulation, users can reconfigure the parameters of the involved objects, so that they can see different effects from the different configurations. This concept is suitable for a classroom learning of physics law. This research studies the Virtual Reality simulation of Newton's physics law on rigid body type of objects. With network support, collaborative interaction is enabled so that people from different places can interact with the same set of objects in immersive Collaborative Virtual Environment. The taxonomy of the interaction in different levels of collaboration is described as: distinct objects and same object, in which there are same object - sequentially, same object - concurrently - same attribute, and same object - concurrently - distinct attributes. The case studies are the interaction of users in two cases: destroying and creating a set of arranged rigid bodies. In Virtual Domino, users can observe physics law while applying force to the domino blocks in order to destroy the arrangements. In Virtual Dollhouse, users can observe physics law while constructing a dollhouse using existing building blocks, under gravity effects.

  6. A Simulated Student Can Improve Collaborative Learning

    OpenAIRE

    Vizcaíno, Aurora

    2005-01-01

    Copyright 2005, the International AIED Society. Permission is hereby granted to copy this article provided that copies are not sold or distributed and that IJAIED is credited. The final, printed version is obtainable on-line from IOS Press; This paper describes a Simulated Student architecture designed to detect and avoid three situations that decrease the benefits of learning in collaboration. These are off-topic conversations, students with passive behaviour and problems related to students...

  7. First International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains: Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, V.; Link, H.; McDade, M.; Mander, A.; Fox, J. C.; Rigas, N.

    2013-11-01

    This report summarizes the proceedings of the First International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains, held from June 13 to 14, 2013, at the National Renewable Energy Laboratory's National Wind Technology Center, located south of Boulder, Colorado. The workshop was sponsored by the U.S. Department of Energy and cohosted by the National Renewable Energy Laboratory and Clemson University under ongoing collaboration via a cooperative research and development agreement. The purpose of the workshop was to provide a forum to discuss the research, testing needs, and state-of-the-art apparatuses involved in grid compliance testing of utility-scale wind turbine generators. This includes both dynamometer testing of wind turbine drivetrains ('ground testing') and field testing grid-connected wind turbines. Four sessions followed by discussions in which all attendees of the workshop were encouraged to participate comprised the workshop.

  8. GRID GENERATION AND NUMERICAL SIMULATION OF 2-D RIVER FLOW GRID GENERATION AND NUMERICAL SIMULATION OF 2-D RIVER FLOW

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents new weighting functions in grid generation and new discretizing scheme of momentum equations in numerical simulation of river flow. By using the new weighting functions, the curvilinear grid could be concentrated as desired near the assigned points or lines in physical plane. By using the new discretizing scheme, the difficulties caused by movable boundary and dry riverbed can be overcome. As an application, the flow in the Wuhan Section of Yangtze River is simulated. The computational results are in good agreement with the measured results. The new method is applicable to the numerical simulation of 2-D river flow with irregular region and moveable boundary.

  9. Research of the grid computing system applied in optical simulation

    Science.gov (United States)

    Jin, Wei-wei; Wang, Yu-dong; Liu, Qiangsheng; Cen, Zhao-feng; Li, Xiao-tong; Lin, Yi-qun

    2008-03-01

    A grid computing in the field of optics is presented in this paper. Firstly, the basic principles and research background of grid computing are outlined in this paper, along with the overview of its applications and the development status quo. The paper also discusses several typical tasks scheduling algorithms. Secondly, it focuses on describing a task scheduling of grid computing applied in optical computation. The paper gives details about the task scheduling system, including the task partition, granularity selection and tasks allocation, especially the structure of the system. In addition, some details of communication on grid computing are also illustrated. In this system, the "makespan" and "load balancing" are comprehensively considered. Finally, we build a grid model to test the task scheduling strategy, and the results are analyzed in detail. Compared to one isolated computer, a grid comprised of one server and four processors can shorten the "makespan" to 1/4. At the same time, the experimental results of the simulation also illustrate that the proposed scheduling system is able to balance loads of all processors. In short, the system performs scheduling well in the grid environment.

  10. Hydrophobic grid membrane filter method for aerobic plate count in foods: collaborative study.

    Science.gov (United States)

    Entis, P

    1986-01-01

    Twenty-one laboratories participated in a collaborative study to validate a hydrophobic grid membrane filter (HGMF) method for aerobic plate count by comparing its performance against the AOAC/APHA pour plate method. Raw milk, raw poultry, whole egg powder, flours, and spices were included in the study. Counts obtained by the HGMF and pour plate methods did not differ significantly, except in the case of whole egg powder, for which the HGMF method produced significantly higher counts. The hydrophobic grid membrane filter method for aerobic plate count in foods has been adopted official first action.

  11. Using 3D Voronoi grids in radiative transfer simulations

    CERN Document Server

    Camps, Peter; Saftly, Waad

    2013-01-01

    Probing the structure of complex astrophysical objects requires effective three-dimensional (3D) numerical simulation of the relevant radiative transfer (RT) processes. As with any numerical simulation code, the choice of an appropriate discretization is crucial. Adaptive grids with cuboidal cells such as octrees have proven very popular, however several recently introduced hydrodynamical and RT codes are based on a Voronoi tessellation of the spatial domain. Such an unstructured grid poses new challenges in laying down the rays (straight paths) needed in RT codes. We show that it is straightforward to implement accurate and efficient RT on 3D Voronoi grids. We present a method for computing straight paths between two arbitrary points through a 3D Voronoi grid in the context of a RT code. We implement such a grid in our RT code SKIRT, using the open source library Voro++ to obtain the relevant properties of the Voronoi grid cells based solely on the generating points. We compare the results obtained through t...

  12. 15 MW HArdware-in-the-loop Grid Simulation Project

    Energy Technology Data Exchange (ETDEWEB)

    Rigas, Nikolaos [Clemson Univ., SC (United States); Fox, John Curtiss [Clemson Univ., SC (United States); Collins, Randy [Clemson Univ., SC (United States); Tuten, James [Clemson Univ., SC (United States); Salem, Thomas [Clemson Univ., SC (United States); McKinney, Mark [Clemson Univ., SC (United States); Hadidi, Ramtin [Clemson Univ., SC (United States); Gislason, Benjamin [Clemson Univ., SC (United States); Boessneck, Eric [Clemson Univ., SC (United States); Leonard, Jesse [Clemson Univ., SC (United States)

    2014-10-31

    The 15MW Hardware-in-the-loop (HIL) Grid Simulator project was to (1) design, (2) construct and (3) commission a state-of-the-art grid integration testing facility for testing of multi-megawatt devices through a ‘shared facility’ model open to all innovators to promote the rapid introduction of new technology in the energy market to lower the cost of energy delivered. The 15 MW HIL Grid Simulator project now serves as the cornerstone of the Duke Energy Electric Grid Research, Innovation and Development (eGRID) Center. This project leveraged the 24 kV utility interconnection and electrical infrastructure of the US DOE EERE funded WTDTF project at the Clemson University Restoration Institute in North Charleston, SC. Additionally, the project has spurred interest from other technology sectors, including large PV inverter and energy storage testing and several leading edge research proposals dealing with smart grid technologies, grid modernization and grid cyber security. The key components of the project are the power amplifier units capable of providing up to 20MW of defined power to the research grid. The project has also developed a one of a kind solution to performing fault ride-through testing by combining a reactive divider network and a large power converter into a hybrid method. This unique hybrid method of performing fault ride-through analysis will allow for the research team at the eGRID Center to investigate the complex differences between the alternative methods of performing fault ride-through evaluations and will ultimately further the science behind this testing. With the final goal of being able to perform HIL experiments and demonstration projects, the eGRID team undertook a significant challenge with respect to developing a control system that is capable of communicating with several different pieces of equipment with different communication protocols in real-time. The eGRID team developed a custom fiber optical network that is based upon FPGA

  13. Training, simulation, restoration expert system for power grid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The paper introduces some technology for training, simulation, restoration expert system of power grid, the structure of the system including function composition, hardware and software composition are discussed, knowledge representation and the method to establish device graphical library for expert system are given, the fault setting and diagnosis for training and simulation as well as restoration technology with deep first searching arithmetic and heuristic inference are presented. The research provides a good base for developing the training, simulation, restoration system of power companies.

  14. Geodynamo and mantle convection simulations on the Earth Simulator using the Yin-Yang grid

    Energy Technology Data Exchange (ETDEWEB)

    Kageyama, Akira; Yoshida, Masaki [Earth Simulator Center, Japan Agency for Marine-Earth Science and Technology, Showa-machi 3173-25, Yokohama (Japan)

    2005-01-01

    We have developed finite difference codes based on the Yin-Yang grid for the geodynamo simulation and the mantle convection simulation. The Yin-Yang grid is a kind of spherical overset grid that is composed of two identical component grids. The intrinsic simplicity of the mesh configuration of the Yin-Yang grid enables us to develop highly optimized simulation codes on massively parallel supercomputers. The Yin-Yang geodynamo code has achieved 15.2 Tflops with 4096 processors on the Earth Simulator. This represents 46% of the theoretical peak performance. The Yin-Yang mantle code has enabled us to carry out mantle convection simulations in realistic regimes with a Rayleigh number of 10{sup 7} including strongly temperature dependent viscosity with spatial contrast up to 10{sup 6}.

  15. Open science grid: Building and sustaining general cyberinfrastructure using a collaborative approach

    OpenAIRE

    2007-01-01

    I describe in this paper the creation and operation of the Open Science Grid (OSG [1]), a distributed shared cyberinfrastructure driven by the milestones of a diverse group of research communities. The effort is fundamentally collaborative, with domain scientists, computer scientists and technology specialists and providers from more than 70 U.S. universities, national laboratories and organizations providing resources, tools and expertise. The evolving OSG facility provides computing and sto...

  16. Complete agent based simulation of mini-grids

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez de Durana, J.M.; Barambones, O. [Univ. of the Basque Country, Vitoria (Spain). Dept. Ingeniera de Sistemas y Automatica; Kremers, E.; Viejo, P. [Karlsruhe Univ., Karlsruhe (Germany). European Inst. for Energy Research

    2009-07-01

    Most people without access to electricity live in remote and rural areas of developing countries where micro-grids have a high potential to actively participate in the electrification of such areas. Micro-grids may be fed by electricity from different renewable and conventional decentralized sources. There are several interesting hybrid renewable energy system (HRES) micro-grid applications, such as mobile equipment; autonomous equipment; small village electricity power supply; water pumping and irrigation systems; communications power supply; and mobile health emergency clinics. This paper presented a review of some of the main types of HRESs. The paper described an agent based model of a simple example of one such system, a micro-grid, oriented to designing a decentralized supervisor control. The model was implemented using AnyLogic and was primarily intended as a tool for design, development and demonstration of micro-grid control strategies. According to simulation results, the model could be used to analyze micro-grid design, operation strategies and economic benefits. 6 refs., 6 figs.

  17. Monte Carlo Simulation Optimizing Design of Grid Ionization Chamber

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Yu-lai; WANG; Qiang; YANG; Lu

    2013-01-01

    The grid ionization chamber detector is often used for measuring charged particles.Based on Monte Carlo simulation method,the energy loss distribution and electron ion pairs of alpha particle with different energy have been calculated to determine suitable filling gas in the ionization chamber filled with

  18. Province Based Design and Simulation of Indonesian Education Grid Topology

    Directory of Open Access Journals (Sweden)

    Heru Suhartanto

    2012-01-01

    Full Text Available This paper discusses the design and simulation of an e-learning computer network topology, based on Grid computing technology, for Indonesian schools called the Indonesian Education Grid (IndoEdu-Grid. The grid technology proposed to solve infrastructure problems faced by Indonesian ICT Network (Jardiknas. In previous study, we designed the topology which based on two scenarios: region based and island based topology. Each scenario run in the simulator using two packet scheduling algorithms, one will be FIFO (First In First Out Scheduler and the other SCFQ (Self-Clocked Fair Queuing Scheduler. In this paper we proposed a different scenario which based on province. The simulation treatments are the same with the two previous scenarios. The simulation results showed that when using FIFO algorithm, the province based scenario has the best performance compared to Region Based and Island Based. However, this scenario is not competitive with the others when using SCFQ algorithm which is due to higher packet lifetime.

  19. 3D COMPOSITIONAL RESERVOIR SIMULATION IN CONJUNCTION WITH UNSTRUCTURED GRIDS

    Directory of Open Access Journals (Sweden)

    A. L. S. Araújo

    Full Text Available Abstract In the last decade, unstructured grids have been a very important step in the development of petroleum reservoir simulators. In fact, the so-called third generation simulators are based on Perpendicular Bisection (PEBI unstructured grids. Nevertheless, the use of PEBI grids is not very general when full anisotropic reservoirs are modeled. Another possibility is the use of the Element based Finite Volume Method (EbFVM. This approach has been tested for several reservoir types and in principle has no limitation in application. In this paper, we implement this approach in an in-house simulator called UTCOMP using four element types: hexahedron, tetrahedron, prism, and pyramid. UTCOMP is a compositional, multiphase/multi-component simulator based on an Implicit Pressure Explicit Composition (IMPEC approach designed to handle several hydrocarbon recovery processes. All properties, except permeability and porosity, are evaluated in each grid vertex. In this work, four case studies were selected to evaluate the implementation, two of them involving irregular geometries. Results are shown in terms of oil and gas rates and saturated gas field.

  20. Electric Vehicle Scenario Simulator Tool for Smart Grid Operators

    OpenAIRE

    Hugo Morais; Zita Vale; João Soares; Cristina Lobo; Bruno Canizes

    2012-01-01

    This paper presents a simulator for electric vehicles in the context of smart grids and distribution networks. It aims to support network operators’ planning and operations but can be used by other entities for related studies. The paper describes the parameters supported by the current version of the Electric Vehicle Scenario Simulator (EVeSSi) tool and its current algorithm. EVeSSi enables the definition of electric vehicles scenarios on distribution networks using a built-in movement engin...

  1. Electric Vehicle Scenario Simulator Tool for Smart Grid Operators

    OpenAIRE

    Hugo Morais; Zita Vale; João Soares; Cristina Lobo; Bruno Canizes

    2012-01-01

    This paper presents a simulator for electric vehicles in the context of smart grids and distribution networks. It aims to support network operators’ planning and operations but can be used by other entities for related studies. The paper describes the parameters supported by the current version of the Electric Vehicle Scenario Simulator (EVeSSi) tool and its current algorithm. EVeSSi enables the definition of electric vehicles scenarios on distribution networks using a built-in movement engin...

  2. Enabling cutting-edge semiconductor simulation through grid technology.

    Science.gov (United States)

    Reid, Dave; Millar, Campbell; Roy, Scott; Roy, Gareth; Sinnott, Richard; Stewart, Gordon; Stewart, Graeme; Asenov, Asen

    2009-06-28

    The progressive scaling of complementary metal oxide semiconductor (CMOS) transistors drives the success of the global semiconductor industry. Detailed knowledge of transistor behaviour is necessary to overcome the many fundamental challenges faced by chip and systems designers. Grid technology has enabled the unavoidable statistical variations introduced by scaling to be examined in unprecedented detail. Over 200 000 transistors have been simulated, the results of which provide detailed insight into underlying physical processes. This paper outlines recent scientific results of the nanoCMOS project and describes the way in which the scientific goals have been reflected in the grid-based e-Infrastructure.

  3. A Scalable Resource Management Architecture for Wide-Area Industrial Measurement Collaboration on Grids

    Institute of Scientific and Technical Information of China (English)

    ZHANG Deng-pan; HE Ling-song; YANG Hong

    2007-01-01

    Research on Web measurement and industrial collaboration in measurement fields in a wide-area and across-organizationally is accepted globally. This paper proposes a novel, scalable management architecture of measurement resources for the resource organization and resource access of the current wide-area collaborative measurement applications in the context of a grid. The complexity of the measurement management on a grid arises from the scale, dynamism, autonomy, heterogeneity, and distribution of the measurement systems and the relative data systems. This paper mainly discusses the interconnection, collaboration, and transparent access of the multi-measurement resources based on the proposed management architecture in the context of complexity. We first discuss the logical architecture used in the measurement fields, and then the resource management system is put at a high premium with layered architecture. Finally, the problems such as resource interconnection, sharing and collaboration are studied in the context of the proposed management environment. The typical applying instance is given to show the advancement of the proposed approach.

  4. NuGrid: Nuclear Burning in 3-D Double Degenerate Merger Simulations

    CERN Document Server

    Diehl, Steven; Hungerford, Aimee; Rockefeller, Gabriel; Bennett, Michael; Herwig, Falk; Hirschi, Raphael; Pignatari, Marco; Magkotsios, Georgios; Timmes, Francis X; Young, Patrick; Clayton, Geoffrey C; Motl, Patrick; Tohline, Joel E

    2008-01-01

    We present preliminary results from recent high-resolution double-degenerate merger simulations with the Smooth Particle Hydrodynamics (SPH) technique. We put particular emphasis on verification and validation in our effort and show the importance of details in the initial condition setup for the final outcome of the simulation. We also stress the dynamical importance of including shocks in the simulations. These results represent a first step toward a suite of simulations that will shed light on the question whether double-degenerate mergers are a viable path toward type 1a supernovae. In future simulations, we will make use of the capabilities of the NuGrid collaboration in post-processing SPH particle trajectories with a complete nuclear network to follow the detailed nuclear reactions during the dynamic merger phase.

  5. Simulations of a multi-layer extended gating grid

    CERN Document Server

    INSPIRE-00507724

    2016-01-01

    A novel idea to control ion back-flow in time projection chambers is to use a multi-layer extended gating grid to capture back-flowing ions at the expense of live time and electron transparency. In this initial study, I perform simulations of a four-layer grid for the ALICE and STAR time projection chambers, using $\\text{Ne}-\\text{CO}_{2}\\;(90-10)$ and $\\text{Ar}-\\text{CH}_{4}\\;(90-10)$ gas mixtures, respectively. I report the live time and electron transparency for both 90% and 99% ion back-flow suppression. Additionally, for the ALICE configuration I study several effects: using a mesh vs. wire-plane grid, including a magnetic field, and varying the over-voltage distribution in the gating region. For 90% ion back-flow suppression, I achieve 75% live time with 86% electron transparency for ALICE, and 95% live time with 83% electron transparency for STAR.

  6. Electric Vehicle Scenario Simulator Tool for Smart Grid Operators

    Directory of Open Access Journals (Sweden)

    Hugo Morais

    2012-06-01

    Full Text Available This paper presents a simulator for electric vehicles in the context of smart grids and distribution networks. It aims to support network operators’ planning and operations but can be used by other entities for related studies. The paper describes the parameters supported by the current version of the Electric Vehicle Scenario Simulator (EVeSSi tool and its current algorithm. EVeSSi enables the definition of electric vehicles scenarios on distribution networks using a built-in movement engine. The scenarios created with EVeSSi can be used by external tools (e.g., power flow for specific analysis, for instance grid impacts. Two scenarios are briefly presented for illustration of the simulator capabilities.

  7. 75 FR 42747 - Smart Grid Update; Notice of Commissioner and Staff Attendance at FERC/NARUC Collaborative on...

    Science.gov (United States)

    2010-07-22

    ... Energy Regulatory Commission Smart Grid Update; Notice of Commissioner and Staff Attendance at FERC/NARUC Collaborative on Smart Response Meeting July 15, 2010. The Federal Energy Regulatory Commission hereby gives.../NARUC Collaborative on Smart Response: Sacramento Convention Center, 1400 J Street, Sacramento, CA 95814...

  8. Simulation for Grid Connected Wind Turbines with Fluctuating

    Science.gov (United States)

    Ye, Ying; Fu, Yang; Wei, Shurong

    This paper establishes the whole dynamic model of wind turbine generator system which contains the wind speed model and DFIG wind turbines model .A simulation sample based on the mathematical models is built by using MATLAB in this paper. Research are did on the performance characteristics of doubly-fed wind generators (DFIG) which connected to power grid with three-phase ground fault and the disturbance by gust and mixed wind. The capacity of the wind farm is 9MW which consists of doubly-fed wind generators (DFIG). Simulation results demonstrate that the three-phase ground fault occurs on grid side runs less affected on the stability of doubly-fed wind generators. However, as a power source, fluctuations of the wind speed will run a large impact on stability of double-fed wind generators. The results also show that if the two disturbances occur in the meantime, the situation will be very serious.

  9. Modeling and simulation of communication networks for smart grid applications; Modellierung und Simulation von Kommunikationsnetzen fuer Smart Grid Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Benoit, Pascal; Rohbogner, Gregor; Fey, Simon; Kohrs, Robert; Wittwer, Christof [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany)

    2012-07-01

    Communication systems will facilitate different new applications in the future Smart Grid. Hence, the design of these systems is of particular importance regarding security, flexibility, usability, robustness and functionality concerns. This article works out the questions for which modeling and simulation of communication networks can be used in finding an engineering solution. Furthermore, it gives a brief overview of the available simulation tools today. Multiagent systems and large-scale photovoltaic plants with tracking systems are two communication intensive applications which are considered as showcases. A model of such a plant will be presented as well as the result of a validation experiment. (orig.)

  10. Climate simulations and services on HPC, Cloud and Grid infrastructures

    Science.gov (United States)

    Cofino, Antonio S.; Blanco, Carlos; Minondo Tshuma, Antonio

    2017-04-01

    Cloud, Grid and High Performance Computing have changed the accessibility and availability of computing resources for Earth Science research communities, specially for Climate community. These paradigms are modifying the way how climate applications are being executed. By using these technologies the number, variety and complexity of experiments and resources are increasing substantially. But, although computational capacity is increasing, traditional applications and tools used by the community are not good enough to manage this large volume and variety of experiments and computing resources. In this contribution, we evaluate the challenges to run climate simulations and services on Grid, Cloud and HPC infrestructures and how to tackle them. The Grid and Cloud infrastructures provided by EGI's VOs ( esr , earth.vo.ibergrid and fedcloud.egi.eu) will be evaluated, as well as HPC resources from PRACE infrastructure and institutional clusters. To solve those challenges, solutions using DRM4G framework will be shown. DRM4G provides a good framework to manage big volume and variety of computing resources for climate experiments. This work has been supported by the Spanish National R&D Plan under projects WRF4G (CGL2011-28864), INSIGNIA (CGL2016-79210-R) and MULTI-SDM (CGL2015-66583-R) ; the IS-ENES2 project from the 7FP of the European Commission (grant agreement no. 312979); the European Regional Development Fund—ERDF and the Programa de Personal Investigador en Formación Predoctoral from Universidad de Cantabria and Government of Cantabria.

  11. Collaborative Science Using Web Services and the SciFlo Grid Dataflow Engine

    Science.gov (United States)

    Wilson, B. D.; Manipon, G.; Xing, Z.; Yunck, T.

    2006-12-01

    Access Protocol (OpenDAP) servers. The scientist injects a distributed computation into the Grid by simply filling out an HTML form or directly authoring the underlying XML dataflow document, and results are returned directly to the scientist's desktop. Once an analysis has been specified for a chunk or day of data, it can be easily repeated with different control parameters or over months of data. Recently, the Earth Science Information Partners (ESIP) Federation sponsored a collaborative activity in which several ESIP members advertised their respective WMS/WCS and SOAP services, developed some collaborative science scenarios for atmospheric and aerosol science, and then choreographed services from multiple groups into demonstration workflows using the SciFlo engine and a Business Process Execution Language (BPEL) workflow engine. For several scenarios, the same collaborative workflow was executed in three ways: using hand-coded scripts, by executing a SciFlo document, and by executing a BPEL workflow document. We will discuss the lessons learned from this activity, the need for standardized interfaces (like WMS/WCS), the difficulty in agreeing on even simple XML formats and interfaces, and further collaborations that are being pursued.

  12. A laboratory grid simulator based on three-phase four-leg inverter

    DEFF Research Database (Denmark)

    Li, Fei; Wang, Xiongfei; Chen, Zhe

    2011-01-01

    This paper presents the design and implementation of a laboratory grid simulator which is used to test the grid-connected devices according to the strict standards. Three-phase four-leg inverter with direct voltage control in Natural Frame is adopted in this grid simulator, which significantly re...... and power quality. Experimental results verify the functionality and performances of the designed grid simulator.......This paper presents the design and implementation of a laboratory grid simulator which is used to test the grid-connected devices according to the strict standards. Three-phase four-leg inverter with direct voltage control in Natural Frame is adopted in this grid simulator, which significantly...

  13. Mass production of extensive air showers for the Pierre Auger Collaboration using Grid Technology

    Science.gov (United States)

    Lozano Bahilo, Julio; Pierre Auger Collaboration

    2012-06-01

    When ultra-high energy cosmic rays enter the atmosphere they interact producing extensive air showers (EAS) which are the objects studied by the Pierre Auger Observatory. The number of particles involved in an EAS at these energies is of the order of billions and the generation of a single simulated EAS requires many hours of computing time with current processors. In addition, the storage space consumed by the output of one simulated EAS is very high. Therefore we have to make use of Grid resources to be able to generate sufficient quantities of showers for our physics studies in reasonable time periods. We have developed a set of highly automated scripts written in common software scripting languages in order to deal with the high number of jobs which we have to submit regularly to the Grid. In spite of the low number of sites supporting our Virtual Organization (VO) we have reached the top spot on CPU consumption among non LHC (Large Hadron Collider) VOs within EGI (European Grid Infrastructure).

  14. Simulation For Synchronization Of A Micro-Grid With Three-Phase Systems

    Directory of Open Access Journals (Sweden)

    Mohammad Jafari Far

    2015-08-01

    Full Text Available Abstract today due to the high reliability of the micro-grids they have developed significantly. They have two states of operation the island state and connection to the main grid. Under certain circumstances the micro-grid is connected to or disconnected from the network. Synchronization of a micro-grid with the network must be done when its voltage is synchronized with the voltage in the main grid. Phase lock loops are responsible to identify the voltage phase of the micro-gird and the main grid and when these two voltages are in the same phase they connect the micro-grid to the main grid. In this research the connection of a micro-grid to the main grid in the two phases of synchronous and asynchronous voltage is simulated and investigated.

  15. Collaborative Simulation Run-time Management Environment Based on HLA

    Institute of Scientific and Technical Information of China (English)

    王江云; 柴旭东; 王行仁

    2002-01-01

    The Collaborative Simulation Run-time Management Environment based on HLA (CSRME) mainly focuses on simulation problems for the system design of the complex distributed simulation. CSRME can integrate all the simulation tools and simulation applications that comply with the well-documented interface standards defined by CSRME. CSRME supports both the interoperability of different simulations and the integration of simulation tools, as well as provides simulation run-time management, simulation time management and simulation data management. Finally, the distributed command training system is analyzed and realized to validate the theories of CSRME.

  16. COLLABORATIVE RESEARCH: CONTINUOUS DYNAMIC GRID ADAPTATION IN A GLOBAL ATMOSPHERIC MODEL: APPLICATION AND REFINEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Prusa, Joseph

    2012-05-08

    This project had goals of advancing the performance capabilities of the numerical general circulation model EULAG and using it to produce a fully operational atmospheric global climate model (AGCM) that can employ either static or dynamic grid stretching for targeted phenomena. The resulting AGCM combined EULAG's advanced dynamics core with the physics of the NCAR Community Atmospheric Model (CAM). Effort discussed below shows how we improved model performance and tested both EULAG and the coupled CAM-EULAG in several ways to demonstrate the grid stretching and ability to simulate very well a wide range of scales, that is, multi-scale capability. We leveraged our effort through interaction with an international EULAG community that has collectively developed new features and applications of EULAG, which we exploited for our own work summarized here. Overall, the work contributed to over 40 peer- reviewed publications and over 70 conference/workshop/seminar presentations, many of them invited.

  17. 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.

  18. Virtual Collaborative Simulation Environment for Integrated Product and Process Development

    Science.gov (United States)

    Gulli, Michael A.

    1997-01-01

    Deneb Robotics is a leader in the development of commercially available, leading edge three- dimensional simulation software tools for virtual prototyping,, simulation-based design, manufacturing process simulation, and factory floor simulation and training applications. Deneb has developed and commercially released a preliminary Virtual Collaborative Engineering (VCE) capability for Integrated Product and Process Development (IPPD). This capability allows distributed, real-time visualization and evaluation of design concepts, manufacturing processes, and total factory and enterprises in one seamless simulation environment.

  19. Power Grid Simulation with GPU-Accelerated Iterative Solvers and Preconditioners

    NARCIS (Netherlands)

    Xu, S.

    2011-01-01

    This thesis deals with two research problems. The first research problem is motivated by the numerical computation involved in the Time Domain Simulation (TDS) of Power Grids. Due to the ever growing size and complexity of Power Grids such as the China National Grid, accelerating TDS has become a st

  20. Model and Simulation for Collaborative VRPSPD

    Directory of Open Access Journals (Sweden)

    Jin Li

    2013-02-01

    Full Text Available This paper studies the collaborative vehicle routing problem of multiple distribution centers with simultaneous pickup and delivery considering the constraint of the number of vehicles and vehicle’s work time, and the fairness of routing arrangement. The objective functions include minimizing the number of utilized vehicles, the travel distance, and the standard deviation of maximum load and vehicle’s utilized time. This paper proposes a mutiobjective mathematical programming model to formulate this problem. And a TS algorithm with Lagrangian Relaxation Approach is designed. This algorithm gives the maximum lower bound of the solutions, achieves the optimal feasible solutions by routes assignment and adjustment strategies. The Tabu Search is embedded with a random neighborhood ordering with restart and shaking methods. The experimental results show that the proposed algorithm presented satisfactory solutions, and the collaborative routing arrangement is more economical, fair, and reasonable than non-collaborative arrangement.

  1. Simulated Social Touch in a Collaborative Game

    NARCIS (Netherlands)

    Huisman, Gijs; Kolkmeijer, Jan; Heylen, Dirk K.J.; Auvray, Malika; Duriez, Christian

    2014-01-01

    In this paper we present a study in which participants played a collaborative augmented reality game together with two virtual agents, visible in the same augmented reality space. During interaction one of the virtual agents touches the user on the arm, by means of a vibrotactile display. We investi

  2. The Numerical Simulation of Ship Waves using Cartesian Grid Methods

    CERN Document Server

    Sussman, Mark

    2014-01-01

    Two different cartesian-grid methods are used to simulate the flow around the DDG 5415. The first technique uses a "coupled level-set and volume-of-fluid" (CLS) technique to model the free-surface interface. The no-flux boundary condition on the hull is imposed using a finite-volume technique. The second technique uses a level-set technique (LS) to model the free-surface interface. A body-force technique is used to impose the hull boundary condition. The predictions of both numerical techniques are compared to whisker-probe measurements of the DDG 5415. The level-set technique is also used to investigate the breakup of a two-dimensional spray sheet.

  3. SEISMIC PROPAGATION SIMULATION IN COMPLEX MEDIA WITH NON-RECTANGULAR IRREGULAR-GRID FINITE-DIFFERENCE

    Institute of Scientific and Technical Information of China (English)

    SUN Weitao; YANG Huizhu

    2004-01-01

    This paper presents a finite-difference (FD) method with spatially non-rectangular irregular grids to simulate the elastic wave propagation. Staggered irregular grid finite difference operators with a second-order time and spatial accuracy are used to approximate the velocity-stress elastic wave equations. This method is very simple and the cost of computing time is not much. Complicated geometries like curved thin layers, cased borehole and nonplanar interfaces may be treated with nonrectangular irregular grids in a more flexible way. Unlike the multi-grid scheme, this method requires no interpolation between the fine and coarse grids and all grids are computed at the same spatial iteration. Compared with the rectangular irregular grid FD, the spurious diffractions from "staircase"interfaces can easily be eliminated without using finer grids. Dispersion and stability conditions of the proposed method can be established in a similar form as for the rectangular irregular grid scheme. The Higdon's absorbing boundary condition is adopted to eliminate boundary reflections. Numerical simulations show that this method has satisfactory stability and accuracy in simulating wave propagation near rough solid-fluid interfaces. The computation costs are less than those using a regular grid and rectangular grid FD method.

  4. Optimal grid-based methods for thin film micromagnetics simulations

    Science.gov (United States)

    Muratov, C. B.; Osipov, V. V.

    2006-08-01

    Thin film micromagnetics are a broad class of materials with many technological applications, primarily in magnetic memory. The dynamics of the magnetization distribution in these materials is traditionally modeled by the Landau-Lifshitz-Gilbert (LLG) equation. Numerical simulations of the LLG equation are complicated by the need to compute the stray field due to the inhomogeneities in the magnetization which presents the chief bottleneck for the simulation speed. Here, we introduce a new method for computing the stray field in a sample for a reduced model of ultra-thin film micromagnetics. The method uses a recently proposed idea of optimal finite difference grids for approximating Neumann-to-Dirichlet maps and has an advantage of being able to use non-uniform discretization in the film plane, as well as an efficient way of dealing with the boundary conditions at infinity for the stray field. We present several examples of the method's implementation and give a detailed comparison of its performance for studying domain wall structures compared to the conventional FFT-based methods.

  5. Nested-grid simulation of mercury over North America

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2012-01-01

    Full Text Available We have developed a new high-resolution (1/2° latitude by 2/3° longitude nested-grid mercury (Hg simulation over North America employing the GEOS-Chem global chemical transport model. Emissions, chemistry, deposition, and meteorology are self-consistent between the global and nested domains. Compared to the global model (4° latitude by 5° longitude, the nested model shows improved skill at capturing the high spatial and temporal variability of Hg wet deposition over North America observed by the Mercury Deposition Network (MDN in 2008–2009. The nested simulation resolves features such as land/ocean contrast and higher deposition due to orographic precipitation, and predicts more efficient convective rain scavenging of Hg over the southeast United States. However, the nested model overestimates Hg wet deposition over the Ohio River Valley region (ORV by 27%. We modify anthropogenic emission speciation profiles in the US EPA National Emission Inventory (NEI to account for the rapid in-plume reduction of reactive to elemental Hg (IPR simulation. This leads to a decrease in the model bias to +3% over the ORV region. Over the contiguous US, the correlation coefficient (r between MDN observations and our IPR simulation increases from 0.63 to 0.78. The IPR nested simulation generally reproduces the seasonal cycle in surface concentrations of speciated Hg from the Atmospheric Mercury Network (AMNet and Canadian Atmospheric Mercury Network (CAMNet. In the IPR simulation, annual mean reactive gaseous and particulate-bound Hg are within 80% and 10% of observations, respectively. In contrast, the simulation with unmodified anthropogenic Hg speciation profiles overestimates these observations by factors of 2 to 4. The nested model shows improved skill at capturing the horizontal variability of Hg observed over California during the ARCTAS aircraft campaign. We find that North American anthropogenic emissions account for 10–22% of Hg wet

  6. Magnetic resonance imaging (MRI) simulation on EGEE grid architecture: a web portal design.

    Science.gov (United States)

    Bellet, F; Nistoreanu, I; Pera, C; Benoit-Cattin, H

    2006-01-01

    In this paper, we present a web portal that enables simulation of MRI images on the grid. Such simulations are done using the SIMRI MRI simulator that is implemented on the grid using MPI and the LCG2 middleware. MRI simulations are mainly used to study MRI sequence, and to validate image processing algorithms. As MRI simulation is computationally very expensive, grid technologies appear to be a real added value for the MRI simulation task. Nevertheless the grid access should be simplified to enable final user running MRI simulations. That is why we develop this specific web portal to propose a user friendly interface for MRI simulation on the grid. The web portal is designed using a three layers client/server architecture. Its main component is the process layer part that manages the simulation jobs. This part is mainly based on a java thread that screens a data base of simulation jobs. The thread submits the new jobs to the grid and updates the status of the running jobs. When a job is terminated, the thread sends the simulated image to the user. Through a client web interface, the user can submit new simulation jobs, get a detailed status of the running jobs, have the history of all the terminated jobs as well as their status and corresponding simulated image.

  7. Business Collaborations in Grids: The BREIN Architectural Principals and VO Model

    Science.gov (United States)

    Taylor, Steve; Surridge, Mike; Laria, Giuseppe; Ritrovato, Pierluigi; Schubert, Lutz

    We describe the business-oriented architectural principles of the EC FP7 project “BREIN” for service-based computing. The architecture is founded on principles of how real businesses interact to mutual benefit, and we show how these can be applied to SOA and Grid computing. We present building blocks that can be composed in many ways to produce different value systems and supply chains for the provision of computing services over the Internet. We also introduce the complementary BREIN VO concept, which is centric to, and managed by, a main contractor who bears the responsibility for the whole VO. The BREIN VO has an execution lifecycle for the creation and operation of the VO, and we have related this to an application-focused workflow involving steps that provide real end-user value. We show how this can be applied to an engineering simulation application and how the workflow can be adapted should the need arise.

  8. GridPACK™ : A Framework for Developing Power Grid Simulations on High-Performance Computing Platforms

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Bruce J.; Perkins, William A.; Chen, Yousu; Jin, Shuangshuang; Callahan, David; Glass, Kevin A.; Diao, Ruisheng; Rice, Mark J.; Elbert, Stephen T.; Vallem, Mallikarjuna R.; Huang, Zhenyu

    2016-05-01

    This paper describes the GridPACK™ framework, which is designed to help power grid engineers develop modeling software capable of running on high performance computers. The framework makes extensive use of software templates to provide high level functionality while at the same time allowing developers the freedom to express whatever models and algorithms they are using. GridPACK™ contains modules for setting up distributed power grid networks, assigning buses and branches with arbitrary behaviors to the network, creating distributed matrices and vectors and using parallel linear and non-linear solvers to solve algebraic equations. It also provides mappers to create matrices and vectors based on properties of the network and functionality to support IO and to mana

  9. Development of Virtual Simulation System for Remote Collaborative Surface Machining

    Institute of Scientific and Technical Information of China (English)

    R.S.Lee; Y.S.Lin; Y.C.Kao; C. H. She

    2006-01-01

    Most researches about virtual machine tool are emphasized on simulations of machine motion and machining process for single machine. In this paper, a virtual simulation system for remote collaborative surface machining is developed. The motion command of machine tool is generated by an interpolator, which can derive synchronized motion commands according to feedrate. Thus, the system can estimate the machining time. For universal assembly of five-axis virtual machine tool, it is based on the D-H notation representation and machining constraints consideration. The remote collaborative virtual manufacturing system based on the CORBA technology is proposed in this paper. It demonstrated that the developed virtual machine tool can be used to verify and simulate the machining process for the collaboration of the surface design and manufacturing team.

  10. Grid Computing

    Science.gov (United States)

    Foster, Ian

    2001-08-01

    The term "Grid Computing" refers to the use, for computational purposes, of emerging distributed Grid infrastructures: that is, network and middleware services designed to provide on-demand and high-performance access to all important computational resources within an organization or community. Grid computing promises to enable both evolutionary and revolutionary changes in the practice of computational science and engineering based on new application modalities such as high-speed distributed analysis of large datasets, collaborative engineering and visualization, desktop access to computation via "science portals," rapid parameter studies and Monte Carlo simulations that use all available resources within an organization, and online analysis of data from scientific instruments. In this article, I examine the status of Grid computing circa 2000, briefly reviewing some relevant history, outlining major current Grid research and development activities, and pointing out likely directions for future work. I also present a number of case studies, selected to illustrate the potential of Grid computing in various areas of science.

  11. Synchronization Algorithms for Co-Simulation of Power Grid and Communication Networks

    Energy Technology Data Exchange (ETDEWEB)

    Ciraci, Selim; Daily, Jeffrey A.; Agarwal, Khushbu; Fuller, Jason C.; Marinovici, Laurentiu D.; Fisher, Andrew R.

    2014-09-11

    The ongoing modernization of power grids consists of integrating them with communication networks in order to achieve robust and resilient control of grid operations. To understand the operation of the new smart grid, one approach is to use simulation software. Unfortunately, current power grid simulators at best utilize inadequate approximations to simulate communication networks, if at all. Cooperative simulation of specialized power grid and communication network simulators promises to more accurately reproduce the interactions of real smart grid deployments. However, co-simulation is a challenging problem. A co-simulation must manage the exchange of informa- tion, including the synchronization of simulator clocks, between all simulators while maintaining adequate computational perfor- mance. This paper describes two new conservative algorithms for reducing the overhead of time synchronization, namely Active Set Conservative and Reactive Conservative. We provide a detailed analysis of their performance characteristics with respect to the current state of the art including both conservative and optimistic synchronization algorithms. In addition, we provide guidelines for selecting the appropriate synchronization algorithm based on the requirements of the co-simulation. The newly proposed algorithms are shown to achieve as much as 14% and 63% im- provement, respectively, over the existing conservative algorithm.

  12. Design, Digital Control, and Simulation of a Grid-Connected Photovoltaic Generation System

    OpenAIRE

    Feshara, Hazem; Elharony, Mohamed; Sharaf, Soliman

    2016-01-01

    This paper presents simulation and digital control of a three-phase grid-connected photovoltaic (PV) generation system. The technique used for maximum power point tracking (MPPT) of photovoltaic power is sliding mode (SM) control. Control of power extraction from DC link capacitor is presented. Space vector pulse width modulation (SVPWM) inverter is utilized to deliver power to utility grid. Simulation is performed using PLECS standalone software package and simulation results are shown. Comp...

  13. A Collaborative Extensible User Environment for Simulation and Knowledge Management

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, Vicky L.; Lansing, Carina S.; Porter, Ellen A.; Schuchardt, Karen L.; Guillen, Zoe C.; Sivaramakrishnan, Chandrika; Gorton, Ian

    2015-06-01

    In scientific simulation, scientists use measured data to create numerical models, execute simulations and analyze results from advanced simulators executing on high performance computing platforms. This process usually requires a team of scientists collaborating on data collection, model creation and analysis, and on authorship of publications and data. This paper shows that scientific teams can benefit from a user environment called Akuna that permits subsurface scientists in disparate locations to collaborate on numerical modeling and analysis projects. The Akuna user environment is built on the Velo framework that provides both a rich client environment for conducting and analyzing simulations and a Web environment for data sharing and annotation. Akuna is an extensible toolset that integrates with Velo, and is designed to support any type of simulator. This is achieved through data-driven user interface generation, use of a customizable knowledge management platform, and an extensible framework for simulation execution, monitoring and analysis. This paper describes how the customized Velo content management system and the Akuna toolset are used to integrate and enhance an effective collaborative research and application environment. The extensible architecture of Akuna is also described and demonstrates its usage for creation and execution of a 3D subsurface simulation.

  14. Visualization of big SPH simulations via compressed octree grids

    KAUST Repository

    Reichl, Florian

    2013-10-01

    Interactive and high-quality visualization of spatially continuous 3D fields represented by scattered distributions of billions of particles is challenging. One common approach is to resample the quantities carried by the particles to a regular grid and to render the grid via volume ray-casting. In large-scale applications such as astrophysics, however, the required grid resolution can easily exceed 10K samples per spatial dimension, letting resampling approaches appear unfeasible. In this paper we demonstrate that even in these extreme cases such approaches perform surprisingly well, both in terms of memory requirement and rendering performance. We resample the particle data to a multiresolution multiblock grid, where the resolution of the blocks is dictated by the particle distribution. From this structure we build an octree grid, and we then compress each block in the hierarchy at no visual loss using wavelet-based compression. Since decompression can be performed on the GPU, it can be integrated effectively into GPU-based out-of-core volume ray-casting. We compare our approach to the perspective grid approach which resamples at run-time into a view-aligned grid. We demonstrate considerably faster rendering times at high quality, at only a moderate memory increase compared to the raw particle set. © 2013 IEEE.

  15. Grid Simulator for Testing a Wind Turbine on Offshore Floating Platform

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, V.

    2012-02-01

    An important aspect of such offshore testing of a wind turbine floating platform is electrical loading of the wind turbine generator. An option of interconnecting the floating wind turbine with the onshore grid via submarine power cable is limited by many factors such as costs and associated environmental aspects (i.e., an expensive and lengthy sea floor study is needed for cable routing, burial, etc). It appears to be a more cost effective solution to implement a standalone grid simulator on a floating platform itself for electrical loading of the test wind turbine. Such a grid simulator must create a stable fault-resilient voltage and frequency bus (a micro grid) for continuous operation of the test wind turbine. In this report, several electrical topologies for an offshore grid simulator were analyzed and modeled.

  16. On a simulation study for reliable and secured smart grid communications

    Science.gov (United States)

    Mallapuram, Sriharsha; Moulema, Paul; Yu, Wei

    2015-05-01

    Demand response is one of key smart grid applications that aims to reduce power generation at peak hours and maintain a balance between supply and demand. With the support of communication networks, energy consumers can become active actors in the energy management process by adjusting or rescheduling their electricity usage during peak hours based on utilities pricing incentives. Nonetheless, the integration of communication networks expose the smart grid to cyber-attacks. In this paper, we developed a smart grid simulation test-bed and designed evaluation scenarios. By leveraging the capabilities of Matlab and ns-3 simulation tools, we conducted a simulation study to evaluate the impact of cyber-attacks on demand response application. Our data shows that cyber-attacks could seriously disrupt smart grid operations, thus confirming the need of secure and resilient communication networks for supporting smart grid operations.

  17. Web-Based Modelling and Collaborative Simulation of Declarative Processes

    DEFF Research Database (Denmark)

    Slaats, Tijs; Marquard, Morten; Shahzad, Muhammad

    2015-01-01

    two years we have taken this adoption of DCR Graphs to the next level and decided to treat the notation as a product of its own by developing a stand-alone web-based collaborative portal for the modelling and simulation of declarative workflows. The purpose of the portal is to facilitate end...

  18. DiSC-OPAL: A Simulation Framework For Real-time Assessment of Distribution Grids

    DEFF Research Database (Denmark)

    Kemal, Mohammed Seifu; Pedersen, Rasmus; Iov, Florin

    2017-01-01

    Smart grid functionalities require developing, testing and verification of complex systems in a realistic environment that captures the three main domains: Control, ICT, and Electrical Grid. Real-time simulations that can support hardware in the loop methods have a pivotal role for modeling of su...

  19. Grid modeling, analysis and simulation of different scenarios for a smart low-voltage distribution grid

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Han, Xue; Bindner, Henrik W.

    2013-01-01

    , the number of cabinets and customers and the load per customer. The aim of the model is to design, implement and test the proposed configuration and to investigate whether the low-voltage distribution grid is prepared for the expected future increase of PV penetration, heat pumps and electric cars. The model...

  20. Cluster Optimization and Parallelization of Simulations with Dynamically Adaptive Grids

    KAUST Repository

    Schreiber, Martin

    2013-01-01

    The present paper studies solvers for partial differential equations that work on dynamically adaptive grids stemming from spacetrees. Due to the underlying tree formalism, such grids efficiently can be decomposed into connected grid regions (clusters) on-the-fly. A graph on those clusters classified according to their grid invariancy, workload, multi-core affinity, and further meta data represents the inter-cluster communication. While stationary clusters already can be handled more efficiently than their dynamic counterparts, we propose to treat them as atomic grid entities and introduce a skip mechanism that allows the grid traversal to omit those regions completely. The communication graph ensures that the cluster data nevertheless are kept consistent, and several shared memory parallelization strategies are feasible. A hyperbolic benchmark that has to remesh selected mesh regions iteratively to preserve conforming tessellations acts as benchmark for the present work. We discuss runtime improvements resulting from the skip mechanism and the implications on shared memory performance and load balancing. © 2013 Springer-Verlag.

  1. Simulation of wind power with front-end converter into interconnected grid system

    Directory of Open Access Journals (Sweden)

    Sharad W. Mohod

    2009-09-01

    Full Text Available In the growing electricity supply industry and open access market for electricity worldwide, renewable sources are getting added into the grid system. This affects the grid power quality. To assess the impact on grid due to wind energy integration, the knowledge of electrical characteristic of wind turbine and associated control equipments are required. The paper presents a simulation set-up for wind turbine in MATLAB / SIMULINK, with front end converter and interconnected system. The presented control scheme provides the wind power flow to the grid through a converter. The injected power in the system at the point of common coupling is ensured within the power quality norms.

  2. A tool for building collaborative applications by invocation of Grid Operations

    NARCIS (Netherlands)

    Malawski, M.; Bartyński, T.; Bubak, M.

    2008-01-01

    The motivation for this work is the need for providing tools which facilitate building scientific applications that are developed and executed on various Grid systems, implemented with different technologies. As a solution to this problem, we have developed the Grid Operation Invoker (GOI) which off

  3. A tool for building collaborative applications by invocation of Grid Operations

    NARCIS (Netherlands)

    Malawski, M.; Bartyński, T.; Bubak, M.

    2008-01-01

    The motivation for this work is the need for providing tools which facilitate building scientific applications that are developed and executed on various Grid systems, implemented with different technologies. As a solution to this problem, we have developed the Grid Operation Invoker (GOI) which

  4. Simulation of offshore wind farm integrated into power grid using VSC HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hui; Nguyen, Mau Cuong; Rudion, Krzystof; Styczynski, Zbigniew Antoni [Magdeburg Univ. (Germany). Chair for Electric Power Networks and Renewable Energy Sources

    2011-07-01

    In this paper, the integration of an offshore wind farm into a power grid is studied based on the simulation of a developed test system including an aggregated DFIG wind farm model and VSC HVDC transmission system model. This paper concentrates on the transient stability and system performance with an applied controller for DFIG and HVDC converter stations. The results are obtained by simulation of the test system subjected to severe grid disturbance, e.g. three-phase short circuit fault at the point of common coupling (PCC). Furthermore, the conformity of the system performance with the current grid code, e.g. fault-ride through capability is investigated and confirmed from the simulation results. In addition, a DC-chopper circuit is modeled to protect the HVDC-link from the overvoltage without disconnection during grid faults. Different time delays of the DC-chopper are considered and simulated to investigate its influence on the system dynamics and performance. (orig.)

  5. Adapting a commercial power system simulator for smart grid based system study and vulnerability assessment

    Science.gov (United States)

    Navaratne, Uditha Sudheera

    The smart grid is the future of the power grid. Smart meters and the associated network play a major role in the distributed system of the smart grid. Advance Metering Infrastructure (AMI) can enhance the reliability of the grid, generate efficient energy management opportunities and many innovations around the future smart grid. These innovations involve intense research not only on the AMI network itself but as also on the influence an AMI network can have upon the rest of the power grid. This research describes a smart meter testbed with hardware in loop that can facilitate future research in an AMI network. The smart meters in the testbed were developed such that their functionality can be customized to simulate any given scenario such as integrating new hardware components into a smart meter or developing new encryption algorithms in firmware. These smart meters were integrated into the power system simulator to simulate the power flow variation in the power grid on different AMI activities. Each smart meter in the network also provides a communication interface to the home area network. This research delivers a testbed for emulating the AMI activities and monitoring their effect on the smart grid.

  6. Numerical Simulation for Flow Distribution in ACE7 Fuel Assemblies affected by a Spacer Grid Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jongpil; Jeong, Ji Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    In spite of various efforts to understand hydraulic phenomena in a rod bundle containing deformed rods due to swelling and/or ballooning of clad, the studies for flow blockage due to spacer grid deformation have been limited. In the present work, 3D CFD analysis for flow blockage was performed to evaluate coolant flow within ACE7 fuel assemblies (FAs) containing a FA affected by a spacer grid deformation. The real geometry except for inner grids was used in the simulation and the region including inner grid was replaced by porous media. In the present work, the numerical simulation was performed to predict coolant flow within ACE7 FAs affected by a Mid grid deformation. The 3D CFD result shows that approximately 60 subchannel hydraulic diameter is required to fully recover coolant flow under normal operating condition.

  7. Symmetry without symmetry: Numerical simulation of axisymmetric systems using Cartesian grids.

    OpenAIRE

    Alcubierre, M.; Brandt, S; Brügmann, B.; Holz, D.; Seidel, E; Takahashi, R.; Thornburg, J.

    2001-01-01

    We present a new technique for the numerical simulation of axisymmetric systems. This technique avoids the coordinate singularities which often arise when cylindrical or polar-spherical coordinate finite difference grids are used, particularly in simulating tenser partial differential equations like those of 3 + 1 numerical relativity. For a system axisymmetric about the r axis, the basic idea is to use a three-dimensional Cartesian (x,y,z) coordinate grid which covers (say) the y = 0 plane, ...

  8. Collaborative simulation method with spatiotemporal synchronization process control

    Science.gov (United States)

    Zou, Yisheng; Ding, Guofu; Zhang, Weihua; Zhang, Jian; Qin, Shengfeng; Tan, John Kian

    2016-10-01

    When designing a complex mechatronics system, such as high speed trains, it is relatively difficult to effectively simulate the entire system's dynamic behaviors because it involves multi-disciplinary subsystems. Currently,a most practical approach for multi-disciplinary simulation is interface based coupling simulation method, but it faces a twofold challenge: spatial and time unsynchronizations among multi-directional coupling simulation of subsystems. A new collaborative simulation method with spatiotemporal synchronization process control is proposed for coupling simulating a given complex mechatronics system across multiple subsystems on different platforms. The method consists of 1) a coupler-based coupling mechanisms to define the interfacing and interaction mechanisms among subsystems, and 2) a simulation process control algorithm to realize the coupling simulation in a spatiotemporal synchronized manner. The test results from a case study show that the proposed method 1) can certainly be used to simulate the sub-systems interactions under different simulation conditions in an engineering system, and 2) effectively supports multi-directional coupling simulation among multi-disciplinary subsystems. This method has been successfully applied in China high speed train design and development processes, demonstrating that it can be applied in a wide range of engineering systems design and simulation with improved efficiency and effectiveness.

  9. Simulation platform developed to study and identify critical cases in a future smart grid

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Zong, Yi; You, Shi

    2016-01-01

    This paper proposes a simulation platform developed to study and identify critical cases in a Smart Grid. A distribution network with different Distributed Energy Resources (DER) components, connected along the feeders, is analyzed, having the objective to identify limitations of existing...... simulation and planning tools, with a particular objective on the challenges faced by the introduction of Smart Grid technologies. Another important issue of the paper is to identify critical load cases, as well as the voltage variations with the highest potential, able to implement the grid model...

  10. Characterization of a Power Electronic Grid Simulator for Wind Turbine Generator Compliance Testing

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Gevorgian, V.; Wallen, R.

    2014-01-01

    This paper presents the commissioning results and testing capabilities of a multi-megawatt power electronic grid simulator situated in National Renewable Energy Laboratory’s (NREL’s) new testing facility. The commissioning is done using a commercial type 4 multi-megawatt sized wind turbine...... generator (WTG) installed in NREL’s new 5 MW dynamometer and a kilowatt sized type 1 WTG connected to the existing 2.5 MW dynamometer at NREL. The paper demonstrates the outstanding testing capability of the grid simulator and its application in the grid code compliance evaluation of WTGs including balanced...

  11. Evaluation of smart grid control strategies in co-simulation - integration of IPSYS and mosaik

    DEFF Research Database (Denmark)

    Kosek, Anna Magdalena; Lünsdorf, Ontje; Scherfke, Stefan

    2014-01-01

    This paper presents two different aspects consid- ering a co-simulation of smart grid scenarios. First considers representing the control strategy in a separate discrete event simulation developed in a multi-agent platform. This study investigates the design and implementation of such a simulator...

  12. BENEFITS OF CPFR AND VMI COLLABORATION STRATEGIES: A SIMULATION STUDY

    OpenAIRE

    Kamalapur, Raj; University of Wisconsin Oshkosh; Lyth, David; Western Michigan University; Houshyar, Azim; Western Michigan University

    2013-01-01

    This study provides managerial insight to pursue Collaborative Planning Forecasting and Replenishment (CPFR) or Vendor Managed Inventory (VMI) strategy for both the retailer and manufacturer under different supply chain settings. Discrete event simulation is used to investigate the cost benefits of CPFR and VMI strategies over Traditional Supply Chain (TSC) in a variable demand environment. The conceptual model is a two-echelon production-inventory system with a manufacturer and a retailer. T...

  13. Participants of the "Grid: the Key to Scientific Collaboration", an outstanding UNESCO-ROSTE and CERN event sponsored by Hewlett Packard held on 28 and 29 September at CERN, Geneva.

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Based on the collaboration-fostering and research-enabling role of the grid, CERN and UNESCO are taking the opportunity to invite current and future grid participants, universities and research institutions to a grid event hosted by CERN in Geneva. Through presentations by key grid protagonists from CERN, the European Commission, the EGEE Grid, and the European research community, participants have been able to learn about the capabilities of the grid, opportunities to leverage their research work, and participation in international projects.

  14. Improved hydrophobic grid membrane filter method, using EF-18 agar, for detection of Salmonella in foods: collaborative study.

    Science.gov (United States)

    Entis, P

    1990-01-01

    A collaborative study was carried out in 30 laboratories to validate improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were included in the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each inoculated in advance with low levels of individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved interim official first action for all foods to replace the HGMF official final action method, 985.42.

  15. Propulsion Electric Grid Simulator (PEGS) for Future Turboelectric Distributed Propulsion Aircraft

    Science.gov (United States)

    Choi, Benjamin B.; Morrison, Carlos; Dever, Timothy; Brown, Gerald V.

    2014-01-01

    NASA Glenn Research Center, in collaboration with the aerospace industry and academia, has begun the development of technology for a future hybrid-wing body electric airplane with a turboelectric distributed propulsion (TeDP) system. It is essential to design a subscale system to emulate the TeDP power grid, which would enable rapid analysis and demonstration of the proof-of-concept of the TeDP electrical system. This paper describes how small electrical machines with their controllers can emulate all the components in a TeDP power train. The whole system model in Matlab/Simulink was first developed and tested in simulation, and the simulation results showed that system dynamic characteristics could be implemented by using the closed-loop control of the electric motor drive systems. Then we designed a subscale experimental system to emulate the entire power system from the turbine engine to the propulsive fans. Firstly, we built a system to emulate a gas turbine engine driving a generator, consisting of two permanent magnet (PM) motors with brushless motor drives, coupled by a shaft. We programmed the first motor and its drive to mimic the speed-torque characteristic of the gas turbine engine, while the second motor and drive act as a generator and produce a torque load on the first motor. Secondly, we built another system of two PM motors and drives to emulate a motor driving a propulsive fan. We programmed the first motor and drive to emulate a wound-rotor synchronous motor. The propulsive fan was emulated by implementing fan maps and flight conditions into the fourth motor and drive, which produce a torque load on the driving motor. The stator of each PM motor is designed to travel axially to change the coupling between rotor and stator. This feature allows the PM motor to more closely emulate a wound-rotor synchronous machine. These techniques can convert the plain motor system into a unique TeDP power grid emulator that enables real-time simulation performance

  16. Effects of mesh style and grid convergence on numerical simulation accuracy of centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    刘厚林; 刘明明; 白羽; 董亮

    2015-01-01

    In order to evaluate the effects of mesh generation techniques and grid convergence on pump performance in centrifugal pump model, three widely used mesh styles including structured hexahedral, unstructured tetrahedral and hybrid prismatic/tetrahedral meshes were generated for a centrifugal pump model. And quantitative grid convergence was assessed based on a grid convergence index (GCI), which accounts for the degree of grid refinement. The structured, unstructured or hybrid meshes are found to have certain difference for velocity distributions in impeller with the change of grid cell number. And the simulation results have errors to different degrees compared with experimental data. The GCI-value for structured meshes calculated is lower than that for the unstructured and hybrid meshes. Meanwhile, the structured meshes are observed to get more vortexes in impeller passage. Nevertheless, the hybrid meshes are found to have larger low-velocity area at outlet and more secondary vortexes at a specified location than structured meshes and unstructured meshes.

  17. A framework for WRF to WRF-IBM grid nesting to enable multiscale simulations

    Energy Technology Data Exchange (ETDEWEB)

    Wiersema, David John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Berkeley, CA (United States); Lundquist, Katherine A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chow, Fotini Katapodes [Univ. of California, Berkeley, CA (United States)

    2016-09-29

    With advances in computational power, mesoscale models, such as the Weather Research and Forecasting (WRF) model, are often pushed to higher resolutions. As the model’s horizontal resolution is refined, the maximum resolved terrain slope will increase. Because WRF uses a terrain-following coordinate, this increase in resolved terrain slopes introduces additional grid skewness. At high resolutions and over complex terrain, this grid skewness can introduce large numerical errors that require methods, such as the immersed boundary method, to keep the model accurate and stable. Our implementation of the immersed boundary method in the WRF model, WRF-IBM, has proven effective at microscale simulations over complex terrain. WRF-IBM uses a non-conforming grid that extends beneath the model’s terrain. Boundary conditions at the immersed boundary, the terrain, are enforced by introducing a body force term to the governing equations at points directly beneath the immersed boundary. Nesting between a WRF parent grid and a WRF-IBM child grid requires a new framework for initialization and forcing of the child WRF-IBM grid. This framework will enable concurrent multi-scale simulations within the WRF model, improving the accuracy of high-resolution simulations and enabling simulations across a wide range of scales.

  18. Simulation-Based Approach for Studying the Balancing of Local Smart Grids with Electric Vehicle Batteries

    Directory of Open Access Journals (Sweden)

    Juhani Latvakoski

    2015-07-01

    Full Text Available Modern society is facing great challenges due to pollution and increased carbon dioxide (CO2 emissions. As part of solving these challenges, the use of renewable energy sources and electric vehicles (EVs is rapidly increasing. However, increased dynamics have triggered problems in balancing energy supply and consumption demand in the power systems. The resulting uncertainty and unpredictability of energy production, consumption, and management of peak loads has caused an increase in costs for energy market actors. Therefore, the means for studying the balancing of local smart grids with EVs is a starting point for this paper. The main contribution is a simulation-based approach which was developed to enable the study of the balancing of local distribution grids with EV batteries in a cost-efficient manner. The simulation-based approach is applied to enable the execution of a distributed system with the simulation of a local distribution grid, including a number of charging stations and EVs. A simulation system has been constructed to support the simulation-based approach. The evaluation has been carried out by executing the scenario related to balancing local distribution grids with EV batteries in a step-by-step manner. The evaluation results indicate that the simulation-based approach is able to facilitate the evaluation of smart grid– and EV-related communication protocols, control algorithms for charging, and functionalities of local distribution grids as part of a complex, critical cyber-physical system. In addition, the simulation system is able to incorporate advanced methods for monitoring, controlling, tracking, and modeling behavior. The simulation model of the local distribution grid can be executed with the smart control of charging and discharging powers of the EVs according to the load situation in the local distribution grid. The resulting simulation system can be applied to the study of balancing local smart grids with EV

  19. Simulation of ozone production in a complex circulation region using nested grids

    Directory of Open Access Journals (Sweden)

    M. Taghavi

    2003-07-01

    Full Text Available During ESCOMPTE precampaign (15 June to 10 July 2000, three days of intensive pollution (IOP0 have been observed and simulated. The comprehensive RAMS model, version 4.3, coupled online with a chemical module including 29 species, has been used to follow the chemistry of the zone polluted over southern France. This online method can be used because the code is paralleled and the SGI 3800 computer is very powerful. Two runs have been performed: run1 with one grid and run2 with two nested grids. The redistribution of simulated chemical species (ozone, carbon monoxide, sulphur dioxide and nitrogen oxides was compared to aircraft measurements and surface stations. The 2-grid run has given substantially better results than the one-grid run only because the former takes the outer pollutants into account. This online method helps to explain dynamics and to retrieve the chemical species redistribution with a good agreement.

  20. Collaborative Classroom Simulation (CCS): An Innovative Pedagogy Using Simulation in Nursing Education.

    Science.gov (United States)

    Berndt, Jodi; Dinndorf-Hogenson, Georgia; Herheim, Rena; Hoover, Carrie; Lanc, Nicole; Neuwirth, Janet; Tollefson, Bethany

    2015-01-01

    Collaborative Classroom Simulation (CCS) is a pedagogy designed to provide a simulation learning experience for a classroom of students simultaneously through the use of unfolding case scenarios. The purpose of this descriptive study was to explore the effectiveness of CCS based on student perceptions. Baccalaureate nursing students (n = 98) participated in the study by completing a survey after participation in the CCS experience. Opportunities for collaboration, clinical judgment, and participation as both observer and active participant were seen as strengths of the experience. Developed as a method to overcome barriers to simulation, CCS was shown to be an effective active learning technique that may prove to be sustainable.

  1. A Novel FPGA-Based Real-Time Simulator for Micro-Grids

    Directory of Open Access Journals (Sweden)

    Bingda Zhang

    2017-08-01

    Full Text Available To meet the requirements of micro-grid real-time simulation, a novel real-time simulator for micro-grids based on Field-Programmable Gate Array (FPGA and orders (FO-RTDS is designed. We describe the design idea of the real-time solver and the order generator. Multi-valued parameter prestorage and multi-rate simulation are introduced to reduce the computational pressure. The data scheduling is carried out following the principle of saving the resources and the minimizing the average distance between variables. An example is performed on XC7VX690T-2FFG1761 chip, which proves the novel FO-RTDS method greatly improves the scale of real-time simulation of micro-grids.

  2. Snowmass Energy Frontier Simulations using the Open Science Grid (A Snowmass 2013 whitepaper)

    Energy Technology Data Exchange (ETDEWEB)

    Avetisyan, Aram [Boston Univ., MA (United States); Bhattacharya, Saptaparna [Brown Univ., Providence, RI (United States); Narain, Meenakshi [Brown Univ., Providence, RI (United States); Padhi, Sanjay [Univ. of California, San Diego, CA (United States); Hirschauer, Jim [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Levshina, Tanya [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); McBride, Patricia [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sehgal, Chander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Slyz, Marko [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Rynge, Mats [Information Sciences Inst., Marina del Rey, CA (United States); Malik, Sudhir [Univ. of Nebraska, Lincoln, NE (United States); Stupak, III, John [Purdue Univ. Northwest, Hammond, IN (United States)

    2013-08-04

    Snowmass is a US long-term planning study for the high-energy community by the American Physical Society's Division of Particles and Fields. For its simulation studies, opportunistic resources are harnessed using the Open Science Grid infrastructure. Late binding grid technology, GlideinWMS, was used for distributed scheduling of the simulation jobs across many sites mainly in the US. The pilot infrastructure also uses the Parrot mechanism to dynamically access CvmFS in order to ascertain a homogeneous environment across the nodes. This report presents the resource usage and the storage model used for simulating large statistics Standard Model backgrounds needed for Snowmass Energy Frontier studies.

  3. Snowmass Energy Frontier Simulations using the Open Science Grid (A Snowmass 2013 whitepaper)

    CERN Document Server

    Avetisyan, A; Narain, M; Padhi, S; Hirschauer, J; Levshina, T; McBride, P; Sehgal, C; Slyz, M; Rynge, M; Malik, S; Stupak, J

    2013-01-01

    Snowmass is a US long-term planning study for the high-energy community by the American Physical Society's Division of Particles and Fields. For its simulation studies, opportunistic resources are harnessed using the Open Science Grid infrastructure. Late binding grid technology, GlideinWMS, was used for distributed scheduling of the simulation jobs across many sites mainly in the US. The pilot infrastructure also uses the Parrot mechanism to dynamically access CvmFS in order to ascertain a homogeneous environment across the nodes. This report presents the resource usage and the storage model used for simulating large statistics Standard Model backgrounds needed for Snowmass Energy Frontier studies.

  4. Fusion Data Grid Service

    Science.gov (United States)

    Shasharina, Svetlana; Wang, Nanbor

    2004-11-01

    Simulations and experiments in the fusion and plasma physics community generate large datasets at remote sites. Visualization and analysis of these datasets are difficult because of the incompatibility among the various data formats adopted by simulation, experiments, and analysis tools, and the large sizes of analyzed data. Grids and Web Services technologies are capable of providing solutions for such heterogeneous settings, but need to be customized to the field-specific needs and merged with distributed technologies currently used by the community. This paper describes how we are addressing these issues in the Fusion Grid Service under development. We also present performance results of relevant data transfer mechanisms including binary SOAP, DIME, GridFTP and MDSplus and CORBA. We will describe the status of data converters (between HDF5 and MDSplus data types), developed in collaboration with MIT (J. Stillerman). Finally, we will analyze bottlenecks of MDSplus data transfer mechanism (work performed in collaboration with General Atomics (D. Schissel and M. Qian).

  5. Real Time Photovoltaic Array Simulator for Testing Grid-Connected PV Inverters

    DEFF Research Database (Denmark)

    Sera, Dezso; Valentini, Massimo; Raducu, Alin

    2008-01-01

    In this paper a real time flexible PV array simulator is presented. It is a system that can simulate different PV panel arrays in specific environmental conditions. To evaluate performance of the Maximum Power Point Tracking (MPPT) of grid-connected Photovoltaic (PV) inverters only measurements...

  6. Parallel Reservoir Simulations with Sparse Grid Techniques and Applications to Wormhole Propagation

    KAUST Repository

    Wu, Yuanqing

    2015-09-08

    In this work, two topics of reservoir simulations are discussed. The first topic is the two-phase compositional flow simulation in hydrocarbon reservoir. The major obstacle that impedes the applicability of the simulation code is the long run time of the simulation procedure, and thus speeding up the simulation code is necessary. Two means are demonstrated to address the problem: parallelism in physical space and the application of sparse grids in parameter space. The parallel code can gain satisfactory scalability, and the sparse grids can remove the bottleneck of flash calculations. Instead of carrying out the flash calculation in each time step of the simulation, a sparse grid approximation of all possible results of the flash calculation is generated before the simulation. Then the constructed surrogate model is evaluated to approximate the flash calculation results during the simulation. The second topic is the wormhole propagation simulation in carbonate reservoir. In this work, different from the traditional simulation technique relying on the Darcy framework, we propose a new framework called Darcy-Brinkman-Forchheimer framework to simulate wormhole propagation. Furthermore, to process the large quantity of cells in the simulation grid and shorten the long simulation time of the traditional serial code, standard domain-based parallelism is employed, using the Hypre multigrid library. In addition to that, a new technique called “experimenting field approach” to set coefficients in the model equations is introduced. In the 2D dissolution experiments, different configurations of wormholes and a series of properties simulated by both frameworks are compared. We conclude that the numerical results of the DBF framework are more like wormholes and more stable than the Darcy framework, which is a demonstration of the advantages of the DBF framework. The scalability of the parallel code is also evaluated, and good scalability can be achieved. Finally, a mixed

  7. 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.

  8. Advanced Grid Simulator for Multi-Megawatt Power Converter Testing and Certification

    Energy Technology Data Exchange (ETDEWEB)

    Koralewicz, Przemyslaw; Gevorgian, Vahan; Wallen, Robb; van der Merwe, Wim; Jorg, Pieder

    2017-02-16

    Grid integration testing of inverter-coupled renewable energy technologies is an essential step in the qualification of renewable energy and energy storage systems to ensure the stability of the power system. New types of devices must be thoroughly tested and validated for compliance with relevant grid codes and interconnection requirements. For this purpose, highly specialized custom-made testing equipment is needed to emulate various types of realistic grid conditions that are required by certification bodies or for research purposes. For testing multi-megawatt converters, a high power grid simulator capable of creating controlled grid conditions and meeting both power quality and dynamic characteristics is needed. This paper describes the new grid simulator concept based on ABB's medium voltage ACS6000 drive technology that utilizes advanced modulation and control techniques to create an unique testing platform for various multi-megawatt power converter systems. Its performance is demonstrated utilizing the test results obtained during commissioning activities at the National Renewable Energy Laboratory in Colorado, USA.

  9. Large-scale lattice Boltzmann simulations of complex fluids: advances through the advent of computational Grids.

    Science.gov (United States)

    Harting, Jens; Chin, Jonathan; Venturoli, Maddalena; Coveney, Peter V

    2005-08-15

    During the last 2.5 years, the RealityGrid project has allowed us to be one of the few scientific groups involved in the development of computational Grids. Since smoothly working production Grids are not yet available, we have been able to substantially influence the direction of software and Grid deployment within the project. In this paper, we review our results from large-scale three-dimensional lattice Boltzmann simulations performed over the last 2.5 years. We describe how the proactive use of computational steering, and advanced job migration and visualization techniques enabled us to do our scientific work more efficiently. The projects reported on in this paper are studies of complex fluid flows under shear or in porous media, as well as large-scale parameter searches, and studies of the self-organization of liquid cubic mesophases.

  10. 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.

  11. Simulation of a flexible wind turbine response to a grid fault

    DEFF Research Database (Denmark)

    Hansen, Anca D.; Cutululis, A. Nicolaos; Sørensen, Poul;

    2007-01-01

    in power system simulation tools applying simplified mechanical models of the drive train. This paper presents simulations of the wind turbine load response to grid faults with an advanced aeroelastic computer code (HAWC2). The core of this code is an advanced model for the flexible structure of the wind...... turbines, taking the flexibility of the tower, blades and other components of the wind turbines into account. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

  12. Interprofessional simulated learning: short-term associations between simulation and interprofessional collaboration

    Directory of Open Access Journals (Sweden)

    van Soeren Mary

    2011-03-01

    Full Text Available Abstract Background Health professions education programs use simulation for teaching and maintaining clinical procedural skills. Simulated learning activities are also becoming useful methods of instruction for interprofessional education. The simulation environment for interprofessional training allows participants to explore collaborative ways of improving communicative aspects of clinical care. Simulation has shown communication improvement within and between health care professions, but the impacts of teamwork simulation on perceptions of others' interprofessional practices and one's own attitudes toward teamwork are largely unknown. Methods A single-arm intervention study tested the association between simulated team practice and measures of interprofessional collaboration, nurse-physician relationships, and attitudes toward health care teams. Participants were 154 post-licensure nurses, allied health professionals, and physicians. Self- and proxy-report survey measurements were taken before simulation training and two and six weeks after. Results Multilevel modeling revealed little change over the study period. Variation in interprofessional collaboration and attitudes was largely attributable to between-person characteristics. A constructed categorical variable indexing 'leadership capacity' found that participants with highest and lowest values were more likely to endorse shared team leadership over physician centrality. Conclusion Results from this study indicate that focusing interprofessional simulation education on shared leadership may provide the most leverage to improve interprofessional care.

  13. Policy Based Access Control in Dynamic Grid-based Collaborative Environment

    NARCIS (Netherlands)

    Y. Demchenko; L. Gommans; A. Tokmakoff; R. van Buuren

    2006-01-01

    This paper describes the design and development of a flexible, customer-driven, security infrastructure for Gridbased Collaborative Environments. The paper proposes further development of the access control model built around a service or resource provisioning agreement (e.g., an experiment or proje

  14. On-demand provisioning of Cloud and Grid based infrastructure services for collaborative projects and groups

    NARCIS (Netherlands)

    Demchenko, Y.; van der Ham, J.; Yakovenko, V.; de Laat, C.; Ghijsen, M.; Cristea, M.; Smari, W.W.; Fox, G.C.

    2011-01-01

    Effective use of existing network and IT infrastructure can be achieved by providing combined network and IT resources on-demand as infrastructure services that are capable of supporting complex technological processes, scientific experiments, and collaborative groups of researchers and applications

  15. Scientific Final Report: COLLABORATIVE RESEARCH: CONTINUOUS DYNAMIC GRID ADAPTATION IN A GLOBAL ATMOSPHERIC MODEL: APPLICATION AND REFINEMENT

    Energy Technology Data Exchange (ETDEWEB)

    William J. Gutowski; Joseph M. Prusa, Piotr K. Smolarkiewicz

    2012-04-09

    This project had goals of advancing the performance capabilities of the numerical general circulation model EULAG and using it to produce a fully operational atmospheric global climate model (AGCM) that can employ either static or dynamic grid stretching for targeted phenomena. The resulting AGCM combined EULAG's advanced dynamics core with the 'physics' of the NCAR Community Atmospheric Model (CAM). Effort discussed below shows how we improved model performance and tested both EULAG and the coupled CAM-EULAG in several ways to demonstrate the grid stretching and ability to simulate very well a wide range of scales, that is, multi-scale capability. We leveraged our effort through interaction with an international EULAG community that has collectively developed new features and applications of EULAG, which we exploited for our own work summarized here. Overall, the work contributed to over 40 peer-reviewed publications and over 70 conference/workshop/seminar presentations, many of them invited.

  16. Grid Sensitivity Analysis of Simulations of a Flow around a Single Rotating Wind Turbine Blade

    Science.gov (United States)

    Kaiser, Bryan E.; Snider, Michael A.; Poroseva, Svetlana V.; Hovsapian, Rob O.

    2012-11-01

    Design of a wind farm layout with the purpose of optimizing the power outcome requires accurate and reliable simulations of a flow around and behind wind turbines. Such computations are expensive even for a single turbine. To find an optimal set of simulation parameters that satisfies both requirements in simulation accuracy and cost in an acceptable degree, a sensitivity study on how the parameters' variation influences results of simulations should be conducted at the early stage of computations. In the current study, the impact of a grid refinement, grid stretching, and cell shape on simulation results is analyzed in a flow around a single rotating blade utilized in a mid-sized Rim Driven Wind Turbine design (U.S. Patent #7399162) developed by Keuka Energy LLC, and in its near wake. Simulation results obtained with structured and unstructured grids are compared. Industry relies on commercial software for conducting fluid flow simulations. Therefore, STAR-CCM+ software was used in our study. A choice of a turbulence model was made based on our previous sensitivity study of flow simulations over a rotating disk (see M. A. Snider, S. V. Poroseva, AIAA-2012-3146). Center for Advanced Power Systems, Florida State University.

  17. How Many Grid Points Are Required for Time Accurate Simulations?

    Science.gov (United States)

    Edoh, Ayaboe; Karagozian, Ann; Mundis, Nathan; Sankaran, Venkateswaran

    2015-11-01

    Grid resolution is a key element in a numerical discretization scheme's ability to accurately capture complex fluid dynamics phenomena encountered in LES and DNS calculations. The fundamental question to be asked concerns the minimum number of points required to represent relevant flow phenomena such as vortex and acoustic wave propagation. The answer is naturally dependent upon the choice of numerical scheme, but it is also influenced by the modal content of the fluid dynamics. Specifically, this study looks at high-order and optimized spatial stencils and their associated dispersion and dissipation characteristics coupled with several time integration schemes. Scheme stabilization is also addressed with respect to artificial dissipation and filtering techniques. The theoretical investigations based on von Neumann analysis are substantiated by calculations of pure mode and multiple mode wave propagation problems, isentropic vortex propagation and the DNS of Taylor Green vortex transition, all of which are used to establish the accuracy properties of the schemes. Distribution A: Approved for public release, distribution unlimited. Supported by AFOSR (PM: Drs. F. Fahroo and Chiping Li).

  18. Hydrophobic grid membrane filter/MUG method for total coliform and Escherichia coli enumeration in foods: collaborative study.

    Science.gov (United States)

    Entis, P

    1989-01-01

    Twenty-four laboratories participated in a collaborative study to validate a hydrophobic grid membrane filter (HGMF) method incorporating the use of 4-methylumbelliferyl-beta-D-glucuronide (MUG) for enumeration of total coliform and Escherichia coli bacteria in foods by comparing its performance against the AOAC 3-tube MPN method (46.013-46.016). Raw milk, raw ground poultry, whole egg powder, cheese powder, and ground black pepper were included in the study. The total coliform methods did not differ significantly, except that the 3-tube method detected a significantly higher level of total coliforms than did the HGMF method in the ground black pepper. Conversely, the HGMF/MUG E. coli method detected significantly higher numbers of E. coli present in the egg powder, cheese powder, and ground black pepper samples, while not differing significantly from the 3-tube method for the raw milk and raw ground poultry samples. The overall confirmation rate of MUG-positive colonies isolated using the HGMF method was 99.5%. The hydrophobic grid membrane filter/MUG method has been adopted official first action as an additional method to AOAC official final action method 46.030-46.034.

  19. Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations

    Directory of Open Access Journals (Sweden)

    S. Nishizawa

    2015-10-01

    Full Text Available We examine the influence of the grid aspect ratio of horizontal to vertical grid spacing on turbulence in the planetary boundary layer (PBL in a large-eddy simulation (LES. In order to clarify and distinguish them from other artificial effects caused by numerical schemes, we used a fully compressible meteorological LES model with a fully explicit scheme of temporal integration. The influences are investigated with a series of sensitivity tests with parameter sweeps of spatial resolution and grid aspect ratio. We confirmed that the mixing length of the eddy viscosity and diffusion due to sub-grid-scale turbulence plays an essential role in reproducing the theoretical −5/3 slope of the energy spectrum. If we define the filter length in LES modeling based on consideration of the numerical scheme, and introduce a corrective factor for the grid aspect ratio into the mixing length, the theoretical slope of the energy spectrum can be obtained; otherwise, spurious energy piling appears at high wave numbers. We also found that the grid aspect ratio has influence on the turbulent statistics, especially the skewness of the vertical velocity near the top of the PBL, which becomes spuriously large with large aspect ratio, even if a reasonable spectrum is obtained.

  20. 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

  1. Structure overset grid method and its applications to simulation of multi-body separation

    Science.gov (United States)

    Zhang, HaiRui; Fan, JingJing; Yuan, Wu; Zhang, WeiHua

    2015-09-01

    This paper proposes an automatic structure overset grid method, which utilizes the hole-surface optimization with one-step searching, wall-surface grid oversetting, and dynamic overset grid approaches to achieve the high adaptability of overset grids for complex multi-body aircrafts. Specifically, based on the automatic structure overset grids, the method first solves the coupling of Navier-Stokes (N-S) unsteady flow equation and 6DOF motion equation, and establishes the multi-body collision model. Then, the numerical simulation of unsteady flow for complex aircrafts' multi-body separation, the simulation of multi-body separating trajectory and the separation safety analysis are accomplished. Thus, the method can properly handle practical engineering problems including the wing/drop tank separation, aircraft/mount separation, and cluster bomb projection. Experiments show that our numerical results match well with experimental results, which demonstrates the effectiveness of our methods in solving the multi-body separation problem for aircrafts with complex shapes.

  2. Grid Computing: A Collaborative Approach in Distributed Environment for Achieving Parallel Performance and Better Resource Utilization

    Directory of Open Access Journals (Sweden)

    Sashi Tarun

    2011-01-01

    Full Text Available From the very beginning various measures are taken or consider for better utilization of available limited resources in the computer system for operational environment, this is came in consideration because most of the time our system get free and not able to exploit the system resource/capabilities as whole cause low performance. Parallel Computing can work efficiently, where operations are handled by multi-processors independently or efficiently, without any other processing capabilities. All processing unit’s works in a parallel fashioned and increases the system throughput without any resource allocation problem among different processing units. But this is limited and effective within a single machine. Today in this computing world, maintaining and establishing high speed computational work environment in a distributed scenario seems to be a challenging task because this environment made all operations by not depending on single resources but by interacting with otherresources in the vast network architecture. All current resource management system can only work smoothly if they apply these resources within their clusters, local organizations or disputed among many users who needs processing power, but for vast distributed environment performing various operational activities seems to be difficult because data is physically not maintained in a centralized location, it is geographically dispersed on multiple remote computers systems. Computers in the distributed environment have to depend on multiple resources for their task completion. Effective performance with high availability of resources to each computer in this speedy distributed computational environment is the major concern. To solve this problem a new approach is coined called “Grid Computing” environment. Grid uses a Middleware to coordinate disparate resources across a network, allows users to function as a virtual whole and make computing fast. In this paper I want to

  3. PAMS - A New Collaborative Framework for Agent-Based Simulation of Complex Sysems

    OpenAIRE

    Nguyen Trong, Khanh; Marilleau, Nicolas; Vinh Ho, Tuong

    2008-01-01

    International audience; Major researches in the domain of complex systems are interdisciplinary, collaborative and geographically distributed. The purpose of our work is to explore a new collaborative approach that facilitates scientist's interactions during the modelling and simulating process. The originality of the presented approach is to consider models and simulators as a board of the collaboration: a shared object manipulated by a group of scientists. Agent-based simulations are powerf...

  4. Web-Based Modelling and Collaborative Simulation of Declarative Processes

    DEFF Research Database (Denmark)

    Slaats, Tijs; Marquard, Morten; Shahzad, Muhammad

    2015-01-01

    As a provider of Electronic Case Management solutions to knowledge-intensive businesses and organizations, the Danish company Exformatics has in recent years identified a need for flexible process support in the tools that we provide to our customers. We have addressed this need by adapting DCR......-user discussions on how knowledge workers really work, by enabling collaborative simulation of processes. In earlier work we reported on the integration of DCR Graphs as a workflow execution formalism in the existing Exformatics ECM products. In this paper we report on the advances we have made over the last two...... years, we describe the new declarative process modelling portal, discuss its features, describe the process of its development, report on the findings of an initial evaluation of the usability of the tool, resulting from a tutorial on declarative modelling with DCR Graphs that we organized at last years...

  5. Simulation of evacuation behaviors in fire using spacial grid

    Institute of Scientific and Technical Information of China (English)

    YANG Lizhong; ZHAO Daoliang; LI Jian; FANG Weifeng; FAN Weicheng

    2004-01-01

    A two-dimensional Cellular Automata (CA) model to demonstrate the special phenomena of occupants evacuating from fire room is presented. A set of simple but effective models is proposed to investigate the effect of fire smoke on route choice. The concept of danger grade is introduced, and occupants select the target cell according to the value of danger grade at each time step. Some technique is introduced to substitute the human intelligence, such as premeditation. The simulation results show that human evacuation is influenced greatly by both human visual field and building exit.

  6. 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.

  7. A derives grid-based model for simulation of pedestrian flow

    Institute of Scientific and Technical Information of China (English)

    Min-jie CHEN; Günter B(A)RWOLFF; Hartmut SCHWANDT

    2009-01-01

    We present a derived grid-based model for the simulation of pedestrian flow. Interactions among pedestrians are considered as the result of forces within a certain neighbourhood. Unlike the social force model, the forces here, as in Newtonian physics, are proportional to the inverse of the square of the distance. Despite the notion of neighbourhood and the underlying grid, this model differs from the existing cellular automaton (CA) models in that the pedestrians are treated as individuals. Bresenham's algorithm for line rastering is applied in the step calculation.

  8. Exponentially Expanded Grid Network Approach (EEGNA) : An Efficient Way for the Simulation of Stiff Electrochemical Problems

    Institute of Scientific and Technical Information of China (English)

    邓兆祥; 林祥钦; 童中华

    2003-01-01

    The exponentially expanded space grid was incorporated into the network approach to overcome the problem of low simulation efficiency during the simulations of electrochemical problems with stiff kinetics or wide dlsperslon of diffusion coefficients, resulting in an effective electrochemical simulation method: exponentially expanded grid network approach (EEG-NA). The stability and accuracy of the EEGNA for the simulation of various electrode processes .coupled with different types of homogeneous reactions were investigated.

  9. Collaborative Learning with Screen-Based Simulation in Health Care Education: An Empirical Study of Collaborative Patterns and Proficiency Development

    Science.gov (United States)

    Hall, L. O.; Soderstrom, T.; Ahlqvist, J.; Nilsson, T.

    2011-01-01

    This article is about collaborative learning with educational computer-assisted simulation (ECAS) in health care education. Previous research on training with a radiological virtual reality simulator has indicated positive effects on learning when compared to a more conventional alternative. Drawing upon the field of Computer-Supported…

  10. Grid-point requirement for large eddy simulation: Chapman's estimation revisited

    Science.gov (United States)

    Choi, Haecheon; Moin, Parviz

    2011-11-01

    Resolution requirements for large eddy simulation (LES), estimated by Chapman [AIAA J. Vol. 17, p. 1293 (1979)], are modified using accurate formulae for high Reynolds number boundary layer flow. This correction indicates that the number of grid points (N) required for wall-modeled LES is proportional to ReL2 / 7 , but a wall-resolving LES requires N ~ReL13 / 7 , where L is the flat-plate length in the streamwise direction. The number of grid points required for the flow over an aircraft using LES with and without modeling the viscous wall region is estimated: the number of grid points for the wall-modeled LES is one to three orders of magnitude smaller than that for the wall-resolving LES, indicating the practical importance of wall modeling in LES for high Reynolds number flows. This work is conducted while HC takes a sabbatical year at Stanford University.

  11. Numerical methods for 3D tokamak simulations using a flux-surface independent grid

    Energy Technology Data Exchange (ETDEWEB)

    Stegmeir, A.; Coster, D.; Maj, O.; Lackner, K. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)

    2014-06-15

    A numerical approach for 3D Tokamak simulations using a flux surface independent grid is presented. The grid consists of few poloidal planes with a Cartesian isotropic grid within each poloidal plane. Perpendicular operators can be discretised within a poloidal plane using standard second order finite difference methods. The discretisation of parallel operators is achieved with a field line following map and an interpolation. The application of the support operator method to the parallel diffusion operator conserves the self-adjointness of the operator on the discrete level and keeps the numerical decay rate at a low level. The developed numerical methods can be applied to geometries where an X-point is present. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Migration of Monte Carlo simulation of high energy atmospheric showers to GRID infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, Adolfo; Contreras, Jose Luis [Grupo de Altas EnergIas Departamento de Fisica Atomica, Molecular y Nuclear Universidad Complutense de Madrid Avenida Complutense s/n, 28040 Madrid - Spain (Spain); Calle, Ignacio de la; Ibarra, Aitor; Tapiador, Daniel, E-mail: avazquez@gae.ucm.e [INSA. IngenierIa y Servicios Aeroespaciales S.A. Paseo Pintor Rosales 34, 28008 Madrid - Spain (Spain)

    2010-04-01

    A system to run Monte Carlo simulations on a Grid environment is presented. The architectural design proposed uses the current resources of the MAGIC Virtual Organization on EGEE and can be easily generalized to support the simulation of any similar experiment, such as that of the future European planned project, the Cherenkov Telescope Array. The proposed system is based on a Client/Server architecture, and provides the user with a single access point to the simulation environment through a remote graphical user interface, the Client. The Client can be accessed via web browser, using web service technology, with no additional software installation on the user side required. The Server processes the user request and uses a database for both data catalogue and job management inside the Grid. The design, first production tests and lessons learned from the system will be discussed here.

  13. Large Eddy Simulations of a Stirred Tank Using the Lattice Boltzmann Method on a Nonuniform Grid

    Science.gov (United States)

    Lu, Zhenyu; Liao, Ying; Qian, Dongying; McLaughlin, J. B.; Derksen, J. J.; Kontomaris, K.

    2002-09-01

    A nonuniform grid lattice Boltzmann technique previously described by He et al. [1] has been extended to simulate three-dimensional flows in complex geometries. The technique is applied to the computation of the turbulent flow in a stirred tank driven by a standard Rushton turbine. With the nonuniform grid approach, the total CPU time required for a simulation of the flow in a stirred tank can be reduced by roughly 75% and still provide the same spatial accuracy as would be obtained with a uniform high-resolution grid. Statistical results for the computed flow fields will be compared with experimental results (H. Wu and G. K. Patterson, Chem. Eng. Sci.44, 2207 (1989)) and with simulations by J. G. M. Eggels ( Int. J. Heat Fluid Flow17, 307 (1996)) and J. J. Derksen and H. E. A. Van den Akker ( AIChE J.45, 209 (1999)). The results of the nonuniform mesh simulation are in reasonable agreement with the available experimental data and the results of previous simulations.

  14. Structured grid technology to enable flow simulation in an integrated system environment

    Science.gov (United States)

    Remotigue, Michael Gerard

    An application-driven Computational Fluid Dynamics (CFD) environment needs flexible and general tools to effectively solve complex problems in a timely manner. In addition, reusable, portable, and maintainable specialized libraries will aid in rapidly developing integrated systems or procedures. The presented structured grid technology enables the flow simulation for complex geometries by addressing grid generation, grid decomposition/solver setup, solution, and interpretation. Grid generation is accomplished with the graphical, arbitrarily-connected, multi-block structured grid generation software system (GUM-B) developed and presented here. GUM-B is an integrated system comprised of specialized libraries for the graphical user interface and graphical display coupled with a solid-modeling data structure that utilizes a structured grid generation library and a geometric library based on Non-Uniform Rational B-Splines (NURBS). A presented modification of the solid-modeling data structure provides the capability for arbitrarily-connected regions between the grid blocks. The presented grid generation library provides algorithms that are reliable and accurate. GUM-B has been utilized to generate numerous structured grids for complex geometries in hydrodynamics, propulsors, and aerodynamics. The versatility of the libraries that compose GUM-B is also displayed in a prototype to automatically regenerate a grid for a free-surface solution. Grid decomposition and solver setup is accomplished with the graphical grid manipulation and repartition software system (GUMBO) developed and presented here. GUMBO is an integrated system comprised of specialized libraries for the graphical user interface and graphical display coupled with a structured grid-tools library. The described functions within the grid-tools library reduce the possibility of human error during decomposition and setup for the numerical solver by accounting for boundary conditions and connectivity. GUMBO is

  15. A staggered overset grid method for resolved simulation of incompressible flow around moving spheres

    Science.gov (United States)

    Vreman, A. W.

    2017-03-01

    An overset grid method for resolved simulation of incompressible (turbulent) flows around moving spherical particles is presented. The Navier-Stokes equations in spherical coordinates are solved on body-fitted spherical polar grids attached to the moving spheres. These grids are overset on a fixed Cartesian background grid, where the Navier-Stokes equations in Cartesian coordinates are solved. The standard second-order staggered finite difference scheme is used on each grid. The velocities and pressures on different grids are coupled by third-order Lagrange interpolations. The method, implemented in the form of a Message Passing Interface parallel program, has been validated for a range of flows around spheres. In a first validation section, the results of simulations of four Stokes flows around a single moving sphere are compared with classical analytical results. The first three cases are the flows due to a translating, an oscillating sphere and a rotating sphere. The numerically produced velocity and pressure fields appear to converge to the corresponding (transient) analytical solutions in the maximum norm. The fourth Stokes case is the flow due to an instantaneously accelerated sphere. For this case, the results are compared with the corresponding numerical solution of the Basset-Boussinesq-Oseen equation. In a second validation section, results of three Navier-Stokes flows around one or more moving spheres are presented. These test configurations are a moving face-centered cubic array of spheres, laminar channel flow with a falling a sphere, and freely moving small spheres in a Taylor-Green flow. Results for the flow with the falling sphere are compared with the results from the literature on immersed boundary methods.

  16. In-situ combustion simulation with dynamic grid; Simulacao de combustao in-situ com grades dinamicas

    Energy Technology Data Exchange (ETDEWEB)

    Ferraz, C.H.A.; Almeida, M.P.; Vasconcelos, H.H.M.; Oliveira, C.L.N. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Fisica

    2008-07-01

    In this work, we study the effects of the introduction of 3D dynamics grids on in-situ combustion simulation results as means of describing the most realistically possible the dynamics of these processes, in particular of the combustion front. The dynamic refinement of grid blocks is important because in thesis it enhances the precision in the calculations once that more grid blocks are considered in the grid, especially within the narrow region of high temperature of the combustion front. We have performed dry combustion simulation (only water injection) and wet combustion simulation (air + water injection) for forward combustion in a variety of well configurations. Our initial results have shown changes in oil, water and gas productions when we use dynamics grids in the simulations, making clear the relevance of its usage in the understanding of the dynamics of these processes. (author)

  17. The Numerical Simulation of Ship Waves Using Cartesian Grid Methods with Adaptive Mesh Refinement

    CERN Document Server

    Dommermuth, Douglas G; Beck, Robert F; O'Shea, Thomas T; Wyatt, Donald C; Olson, Kevin; MacNeice, Peter

    2014-01-01

    Cartesian-grid methods with Adaptive Mesh Refinement (AMR) are ideally suited for simulating the breaking of waves, the formation of spray, and the entrainment of air around ships. As a result of the cartesian-grid formulation, minimal input is required to describe the ships geometry. A surface panelization of the ship hull is used as input to automatically generate a three-dimensional model. No three-dimensional gridding is required. The AMR portion of the numerical algorithm automatically clusters grid points near the ship in regions where wave breaking, spray formation, and air entrainment occur. Away from the ship, where the flow is less turbulent, the mesh is coarser. The numerical computations are implemented using parallel algorithms. Together, the ease of input and usage, the ability to resolve complex free-surface phenomena, and the speed of the numerical algorithms provide a robust capability for simulating the free-surface disturbances near a ship. Here, numerical predictions, with and without AMR,...

  18. Collaboration

    Science.gov (United States)

    King, Michelle L.

    2010-01-01

    This article explores collaboration between library media educators and regular classroom teachers. The article focuses on the context of the issue, positions on the issue, the impact of collaboration, and how to implement effective collaboration into the school system. Various books and professional journals are used to support conclusions…

  19. On the Origin of Grid Anisotropy in the Simulation of Dendrite Growth by a VFT Model

    Science.gov (United States)

    Djaraoui, Afaf; Nebti, Samia

    2016-10-01

    A virtual front tracking model, based on solute and heat diffusion in two dimensions, is chosen to capture the full microstructural behavior of dendritic solidification in a binary alloy. We use a simple method of calculation, easy to perform, with relatively high stable time step, to simulate the dendrite growth in an Al-8 wt pct Mg alloy for which no numerical simulation has been carried out in the past. Local equilibrium at the liquid solid interface and the buildup of solute ahead of the interface are solved, and the dendrite growth process is simulated in isothermal solidification conditions. We show that the artificial grid anisotropy originates from the four cell neighborhood method adopted for capturing the moving front. By a correct neighborhood configuration, a grid independent set of results and expected phenomena are reproduced for a free dendrite growing either aligned or inclined with the grid. The dendrite morphology and orientation, and the growth velocity are explored via physical simulation parameters such as undercooling and surface tension anisotropy.

  20. Speeding up the flash calculations in two-phase compositional flow simulations - The application of sparse grids

    KAUST Repository

    Wu, Yuanqing

    2015-03-01

    Flash calculations have become a performance bottleneck in the simulation of compositional flow in subsurface reservoirs. We apply a sparse grid surrogate model to substitute the flash calculation and thus try to remove the bottleneck from the reservoir simulation. So instead of doing a flash calculation in each time step of the simulation, we just generate a sparse grid approximation of all possible results of the flash calculation before the reservoir simulation. Then we evaluate the constructed surrogate model to approximate the values of the flash calculation results from this surrogate during the simulations. The execution of the true flash calculation has been shifted from the online phase during the simulation to the offline phase before the simulation. Sparse grids are known to require only few unknowns in order to obtain good approximation qualities. In conjunction with local adaptivity, sparse grids ensure that the accuracy of the surrogate is acceptable while keeping the memory usage small by only storing a minimal amount of values for the surrogate. The accuracy of the sparse grid surrogate during the reservoir simulation is compared to the accuracy of using a surrogate based on regular Cartesian grids and the original flash calculation. The surrogate model improves the speed of the flash calculations and the simulation of the whole reservoir. In an experiment, it is shown that the speed of the online flash calculations is increased by about 2000 times and as a result the speed of the reservoir simulations has been enhanced by 21 times in the best conditions.

  1. Simulation-based Validation of Smart Grids - Status Quo and Future Research Trends

    DEFF Research Database (Denmark)

    Steinbrink, C.; Lehnhoff, S.; Rohjans, S.

    2017-01-01

    such cyber-physical energy systems with a high(er) penetration of fluctuating renewable generation and controllable loads. As a result of these developments the validation on the system level becomes much more important during the whole engineering and deployment process, today. In earlier development stages......Smart grid systems are characterized by high complexity due to interactions between a traditional passive network and active power electronic components, coupled using communication links. Additionally, automation and information technology plays an important role in order to operate and optimize...... and for larger system configurations laboratory-based testing is not always an option. Due to recent developments, simulation-based approaches are now an appropriate tool to support the development, implementation, and rollout of smart grid solutions. This paper discusses the current state of simulation...

  2. Application of multi-grid method on the simulation of incremental forging processes

    Science.gov (United States)

    Ramadan, Mohamad; Khaled, Mahmoud; Fourment, Lionel

    2016-10-01

    Numerical simulation becomes essential in manufacturing large part by incremental forging processes. It is a splendid tool allowing to show physical phenomena however behind the scenes, an expensive bill should be paid, that is the computational time. That is why many techniques are developed to decrease the computational time of numerical simulation. Multi-Grid method is a numerical procedure that permits to reduce computational time of numerical calculation by performing the resolution of the system of equations on several mesh of decreasing size which allows to smooth faster the low frequency of the solution as well as its high frequency. In this paper a Multi-Grid method is applied to cogging process in the software Forge 3. The study is carried out using increasing number of degrees of freedom. The results shows that calculation time is divide by two for a mesh of 39,000 nodes. The method is promising especially if coupled with Multi-Mesh method.

  3. Impact of Interprofessional Simulation on Nursing Students' Attitudes Toward Teamwork and Collaboration.

    Science.gov (United States)

    Krueger, Linda; Ernstmeyer, Kim; Kirking, Ellen

    2017-06-01

    The purpose of this study was to examine the influence of a multipatient, interprofessional simulation session on nursing students' attitudes toward nurse-physician collaboration using the Jefferson Scale of Attitudes Toward Physician-Nurse Collaboration. Final-semester nursing students, along with medical resident and students from other health programs, participated in a simulation exercise that included a period of prebriefing, simulation, and debriefing. Participants completed pre- and postsimulation surveys to assess the impact on collaboration. In total, 268 nursing students completed the survey. Participants had a more positive attitude toward nurse-physician collaboration following the simulation event, compared with prior to it. Significant differences between male and female nursing students were found on mean postsimulation scores and for three of the four subscales of the tool. Interprofessional simulation may be an effective way to enhance collaborative relationships, which ultimately may influence patient safety and quality of care. [J Nurs Educ. 2017;56(6):321-327.]. Copyright 2017, SLACK Incorporated.

  4. Co-Simulation of Detailed Whole Building with the Power System to Study Smart Grid Applications

    Energy Technology Data Exchange (ETDEWEB)

    Makhmalbaf, Atefe; Fuller, Jason C.; Srivastava, Viraj; Ciraci, Selim; Daily, Jeffrey A.

    2014-12-24

    Modernization of the power system in a way that ensures a sustainable energy system is arguably one of the most pressing concerns of our time. Buildings are important components in the power system. First, they are the main consumers of electricity and secondly, they do not have constant energy demand. Conventionally, electricity has been difficult to store and should be consumed as it is generated. Therefore, maintaining the demand and supply is critical in the power system. However, to reduce the complexity of power models, buildings (i.e., end-use loads) are traditionally modeled and represented as aggregated “dumb” nodes in the power system. This means we lack effective detailed whole building energy models that can support requirements and emerging technologies of the smart power grid. To gain greater insight into the relationship between building energy demand and power system performance, it is important to constitute a co-simulation framework to support detailed building energy modeling and simulation within the power system to study capabilities promised by the modern power grid. This paper discusses ongoing work at Pacific Northwest National Laboratory and presents underlying tools and framework needed to enable co-simulation of building, building energy systems and their control in the power system to study applications such as demand response, grid-based HVAC control, and deployment of buildings for ancillary services. The optimal goal is to develop an integrated modeling and simulation platform that is flexible, reusable, and scalable. Results of this work will contribute to future building and power system studies, especially those related to the integrated ‘smart grid’. Results are also expected to advance power resiliency and local (micro) scale grid studies where several building and renewable energy systems transact energy directly. This paper also reviews some applications that can be supported and studied using the framework introduced

  5. Simulation Model of the Future Nordic Power Grid Considering the Impact of HVDC Links

    OpenAIRE

    Aas, Even Strand

    2016-01-01

    As Europe is shifting to an increasingly larger share of non-dispatchable renewable energy sources, the cross-border power flow changes. This thesis considers further development of an existing PowerFactory simulation model designed to fit with new power flow situations influencing the Nordic power system. Today, there are many HVDC links connecting Europe to the Nordic grid, and there are several new links being built and planned. The thesis work is a continuation of an earlier specialisatio...

  6. SWAT use of gridded observations for simulating runoff – a Vietnam river basin study

    Directory of Open Access Journals (Sweden)

    M. T. Vu

    2011-12-01

    Full Text Available Many research studies that focus on basin hydrology have used the SWAT model to simulate runoff. One common practice in calibrating the SWAT model is the application of station data rainfall to simulate runoff. But over regions lacking robust station data, there is a problem of applying the model to study the hydrological responses. For some countries and remote areas, the rainfall data availability might be a constraint due to many different reasons such as lacking of technology, war time and financial limitation that lead to difficulty in constructing the runoff data. To overcome such a limitation, this research study uses some of the available globally gridded high resolution precipitation datasets to simulate runoff. Five popular gridded observation precipitation datasets: (1 Asian Precipitation Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources (APHRODITE, (2 Tropical Rainfall Measuring Mission (TRMM, (3 Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIANN, (4 Global Precipitation Climatology Project (GPCP, (5 modified Global Historical Climatology Network version 2 (GHCN2 and one reanalysis dataset National Centers for Environment Prediction/National Center for Atmospheric Research (NCEP/NCAR are used to simulate runoff over the Dakbla River (a small tributary of the Mekong River in Vietnam. Wherever possible, available station data are also used for comparison. Bilinear interpolation of these gridded datasets is used to input the precipitation data at the closest grid points to the station locations. Sensitivity Analysis and Auto-calibration are performed for the SWAT model. The Nash-Sutcliffe Efficiency (NSE and Coefficient of Determination (R2 indices are used to benchmark the model performance. This entails a good understanding of the response of the hydrological model to different datasets and a quantification of the uncertainties in

  7. Three-Dimensional Simulation of SOFC Anode Polarization Characteristics Based on Sub-Grid Scale Model

    OpenAIRE

    2011-01-01

    Three-dimensional numerical simulation of SOFC anode polarization is conducted with a structure obtained by a focused ion beam and scanning electron microscope (FIB-SEM). Electronic, ionic and gaseous transports with electrochemical reaction are considered. A sub-grid scale model is newly developed and effectively used to evaluate the transport flux in the porous structure. The proposed SGS model shows its potential to reasonably evaluate the transport flux considering the microstructure smal...

  8. Improvement of prediction accuracy of large eddy simulation on colocated grids; Colocation koshi wo mochiita LES no keisan seido kaizen ni kansuru ichikosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Inagaki, M.; Abe, K. [Toyota Central Research and Development Labs., Inc., Aichi (Japan)

    1998-07-25

    With the recent advances in computers, large eddy simulation (LES) has become applicable to engineering prediction. However, most cases of the engineering applications need to use the nonorthgonal curvilimear coordinate systems. The staggered grids, usually used in LES in the orthgonal coordinates, don`t keep conservative properties in the nonorthgonal curvilinear coordinates. On the other hand, the colocated grids can be applied in the nonorthgonal curvilinear coordinates without losing its conservative properties, although its prediction accuracy isn`t so high as the staggered grid`s in the orthgonal coordinates especially with the coarse grids. In this research, the discretization method of the colocated grids is modified to improve its prediction accuracy. Plane channel flows are simulated on four grids of different resolution using the modified colocated grids and the original colocated grids. The results show that the modified colocated grids have higher accuracy than the original colocated grids. 17 refs., 13 figs., 1 tab.

  9. Universal Electrochemical/Chemical Simulator Based on an Exponentially Expanding Grid Network Approach

    Institute of Scientific and Technical Information of China (English)

    DENG,Zhao-Xiang(邓兆祥); LIN,Xiang-Qin(林祥钦); TONG,Zhong-Hua(童中华)

    2004-01-01

    A universal simulator capable of simulating virtually any user-defined electrochemical/chemical problems in one-dimensional diffusion geometry was developed based on an exponentially expanding grid modification of the existing network approach. Some generalized reaction-diffusion governing equations of an arbitrary electrochemical/chemical process were derived, and program controlled automatic generation of the corresponding PSPICE netlist file was realized. On the basis of the above techniques, a universal simulator package was realized, which is capable of dealing with arbitrarily complex electrochemical/chemical problems with one-dimensional diffusion geometry such as planar diffusion, spherical diffusion, cylindrical diffusion and rotational disk diffusion-convection processes. The building of such a simulator is easy and thus it would be very convenient to have it updated for simulations of newly raised electrochemical problems.

  10. Transient Stability Analysis of Grid-connected Wind Turbines with Time Domain Simulation

    Directory of Open Access Journals (Sweden)

    Shuaibing Li

    2013-07-01

    Full Text Available With an ever-increasing pentration of wind power into power system, the influence to overall system behavior and stability becomes obviously. Therefore, it is so necessary to require wind turbines have good grid adaptability. This paper investigates the effect of directly grid-connected front-end speed controlled wind turbines (FSCWT on transient stability of power system.For this purpose, a voltage based synchronous generator model is used and the drive train model with WinDriver is built. By using a fast excitation control of FSCWT exciter, the FSCWT wind turbines can successfully ride through grid fault and have no problem of angular stability when connected to grid. Simulation studies are carried out to demonstrate and compare the transient performance of the IEEE 5-machine 14-bus system with FSCWT replace by double fed induction generators (DFIG during a three phase fault. Results show that a better transient stability performance is achieved with an intergration of FSCWT in comparsion with DFIG, which can even bring some benefits on power system transient performance and stability.

  11. Grid-point requirements for large eddy simulation: Chapman's estimates revisited

    Science.gov (United States)

    Choi, Haecheon; Moin, Parviz

    2012-01-01

    Resolution requirements for large eddy simulation (LES), estimated by Chapman [AIAA J. 17, 1293 (1979)], are modified using accurate formulae for high Reynolds number boundary layer flow. The new estimates indicate that the number of grid points (N) required for wall-modeled LES is proportional to ReLx , but a wall-resolving LES requires N ˜ReLx 13 /7 , where Lx is the flat-plate length in the streamwise direction. On the other hand, direct numerical simulation, resolving the Kolmogorov length scale, requires N ˜ReLx 37 /14 .

  12. Simulation Modeling and Statistical Network Tools for Improving Collaboration in Military Logistics

    Science.gov (United States)

    2008-10-01

    AFRL-RH-WP-TR-2009-0110 Simulation Modeling and Statistical Network Tools for Improving Collaboration in Military Logistics...SUBTITLE Simulation Modeling and Statistical Network Tools for Improving Collaboration in Military Logistics 5a. CONTRACT NUMBER FA8650-07-1-6848...8 1 1.0 SUMMARY This final technical report describes the research findings of the project Simulation Modeling and Statistical Network

  13. Unsteady Non-Newtonian Solver on Unstructured Grid for the Simulation of Blood Flow

    Directory of Open Access Journals (Sweden)

    Guojie Li

    2013-01-01

    Full Text Available Blood is in fact a suspension of different cells with yield stress, shear thinning, and viscoelastic properties, which can be represented by different non-Newtonian models. Taking Casson fluid as an example, an unsteady solver on unstructured grid for non-Newtonian fluid is developed to simulate transient blood flow in complex flow region. In this paper, a steady solver for Newtonian fluid is firstly developed with the discretization of convective flux, diffusion flux, and source term on unstructured grid. For the non-Newtonian characteristics of blood, the Casson fluid is approximated by the Papanastasiou's model and treated as Newtonian fluid with variable viscosity. Then considering the transient property of blood flow, an unsteady non-Newtonian solver based on unstructured grid is developed by introducing the temporal term by first-order upwind difference scheme. Using the proposed solver, the blood flows in carotid bifurcation of hypertensive patients and healthy people are simulated. The result shows that the possibility of the genesis and development of atherosclerosis is increased, because of the increase in incoming flow shock and backflow areas of the hypertensive patients, whose WSS was 20~87.1% lower in outer vascular wall near the bifurcation than that of the normal persons and 3.7~5.5% lower in inner vascular wall downstream the bifurcation.

  14. Use of hourly sequences of global radiation for simulation of photovoltaic systems grid connected

    Energy Technology Data Exchange (ETDEWEB)

    Sidrach de Cardona, M. [Dept. Fisica Aplicada 2, E.T.S.I., Univ. de Malaga (Spain); Mora Lopez, Ll. [Dept. Lenguajes y Ciencias de la Computacion, E.T.S.I., Univ. de Malaga (Spain)

    1996-12-31

    In this paper we analyse whether it is suitable to use hourly sequences of global radiation to study the performance of photovoltaic systems grid connected. The purpose of this paper is to quantify the error which is made on predicting the energy which a photovoltaic system connected to the grid, when the global radiation interval considered (which is an input value in our computations) varies. Using a simulation model we have studied how much energy is produced. The input values we considered are: values of daily global radiation, values of hourly global radiation and global radiation intervals of 10 minutes. These data have been recorded by the metereological station in Malaga of Andalusian Institute for renewable energies. In each interval, the simulation model takes into account the variations in module temperature as a function of ambient temperature. Therefore, when using daily values the model takes into account the average value of ambient temperature during sun hours and when using other values the model takes into account the average of this parameter in the interval under consideration. The nominal power considered is 2 kWp. The model we use assumes that the working point of the installation is always the maximum power point of modules and that all produced energy is injected in the grid. We also study the influence on this error when different set point of minimum input power for inverter starting (threshold value) are used. (orig.)

  15. Increasing self-consumption of photovoltaic electricity by storing energy in electric vehicle using smart grid technology in the residential sector. A model for simulating different smart grid programs

    NARCIS (Netherlands)

    Kam, M. van der; Sark, W.G.J.H.M. van

    2014-01-01

    In this paper a model has been developed which intends to simulate the increase of self-consumption of photovoltaic (PV)-power by storing energy in electric vehicle (EV) using smart grid technology in the residential sector. Three different possible smart grid control algorithms for a micro-grid con

  16. Simulation of the anode structure for capacitive Frisch grid CdZnTe detectors

    Institute of Scientific and Technical Information of China (English)

    MIN Jiahua; SHI Zhubin; QIAN Yongbiao; SANG Wenbin; ZHAO Hengyu; TENG Jianyong; LIU Jishan

    2009-01-01

    CdZnTe (CZT) capacitive Frisch grid detectors can achieve a higher detecting resolution.The anode structure might have an important role in improving the weighting potential distribution of the detectors.In this paper,four anode structures of capacitive Frisch grid structures have been analyzed with FE simulation,based on a 3-dimensional weighting potential analysis.The weighting potential distributions in modified anode devices (Model B,C and D) are optimized compared with a square device (Model A).In model C and D,the abrupt weighting potential can be well modified.However,with increased radius of the circular electrode in Model C the weighting potential platform away from the anode becomes higher and higher and in Model D,the weighting potential does not vary too much.

  17. Nucleosynthesis simulations for a wide range of nuclear production sites from NuGrid

    CERN Document Server

    Herwig, Falk; Diehl, Steven; Fryer, Christopher L; Hirschi, Raphael; Hungerford, Aimee; Magkotsios, Georgios; Pignatari, Marco; Rockefeller, Gabriel; Timmes, Francis X; Young, Patrick

    2008-01-01

    Simulations of nucleosynthesis in astrophysical environments are at the intersection of nuclear physics reaction rate research and astrophysical applications, for example in the area of galactic chemical evolution or near-field cosmology. Unfortunately, at present the available yields for such applications are based on heterogeneous assumptions between the various contributing nuclear production sites, both in terms of modeling the thermodynamic environment itself as well as the choice of specifc nuclear reaction rates and compilations. On the other side, new nuclear reaction rate determinations are often taking a long time to be included in astrophysical applications. The NuGrid project addresses these issues by providing a set of codes and a framework in which these codes interact. In this contribution we describe the motivation, goals and first results of the NuGrid project. At the core is a new and evolving post-processing nuclesoynthesis code (PPN) that can follow quiescent and explosive nucleosynthesis ...

  18. Simulation of plasma based semiconductor processing using block structured locally refined grids

    Energy Technology Data Exchange (ETDEWEB)

    Wake, D.D.

    1998-01-01

    We have described a new numerical method for plasma simulation. Calculations have been presented which show that the method is accurate and suggest the regimes in which the method provides savings in CPU time and memory requirements. A steady state simulation of a four centimeter domain was modeled with sheath scale (150 microns) resolution using only 40 grid points. Simulations of semiconductor processing equipment have been performed which imply the usefulness of the method for engineering applications. It is the author`s opinion that these accomplishments represent a significant contribution to plasma simulation and the efficient numerical solution of certain systems of non-linear partial differential equations. More work needs to be done, however, for the algorithm to be of practical use in an engineering environment. Despite our success at avoiding the dielectric relaxation timestep restrictions the algorithm is still conditionally stable and requires timesteps which are relatively small. This represents a prohibitive runtime for steady state solutions on high resolution grids. Current research suggests that these limitations may be overcome and the use of much larger timesteps will be possible.

  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. Grid Application for the BaBar Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Khan, A.; /Brunel U.; Wilson, F.; /Rutherford

    2006-08-14

    This paper discusses the use of e-Science Grid in providing computational resources for modern international High Energy Physics (HEP) experiments. We investigate the suitability of the current generation of Grid software to provide the necessary resources to perform large-scale simulation of the experiment and analysis of data in the context of multinational collaboration.

  1. Collaboration.

    Science.gov (United States)

    McDonald, Meme; Pryor, Boori Monty

    2000-01-01

    Describes, in the words of two Australian authors (one Aboriginal and one European-Australian), how they work together when they write books together, and how their collaboration goes beyond the two of them. (SR)

  2. When Feedback Harms and Collaboration Helps in Computer Simulation Environments: An Expertise Reversal Effect

    Science.gov (United States)

    Nihalani, Priya K.; Mayrath, Michael; Robinson, Daniel H.

    2011-01-01

    We investigated the effects of feedback and collaboration on undergraduates' transfer performance when using a computer networking training simulation. In Experiment 1, 65 computer science "novices" worked through an instructional protocol individually (control), individually with feedback, or collaboratively with feedback. Unexpectedly,…

  3. 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...

  4. Experiences Integrating Transmission and Distribution Simulations for DERs with the Integrated Grid Modeling System (IGMS)

    Energy Technology Data Exchange (ETDEWEB)

    Palmintier, Bryan; Hale, Elaine; Hodge, Bri-Mathias; Baker, Kyri; Hansen, Timothy M.

    2016-08-11

    This paper discusses the development of, approaches for, experiences with, and some results from a large-scale, high-performance-computer-based (HPC-based) co-simulation of electric power transmission and distribution systems using the Integrated Grid Modeling System (IGMS). IGMS was developed at the National Renewable Energy Laboratory (NREL) as a novel Independent System Operator (ISO)-to-appliance scale electric power system modeling platform that combines off-the-shelf tools to simultaneously model 100s to 1000s of distribution systems in co-simulation with detailed ISO markets, transmission power flows, and AGC-level reserve deployment. Lessons learned from the co-simulation architecture development are shared, along with a case study that explores the reactive power impacts of PV inverter voltage support on the bulk power system.

  5. Development of a Parallel Overset Grid Framework for Moving Body Simulations in OpenFOAM

    Directory of Open Access Journals (Sweden)

    Dominic Chandar

    2015-12-01

    Full Text Available OpenFOAM is an industry-standard Open-Source fluid dynamics code that is used to solve the Navier-Stokes equations for a variety of flow situations. It is currently being used extensively by researchers to study a plethora of physical problems ranging from fundamental fluid dynamics to complex multiphase flows. When it comes to modeling the flow surrounding moving bodies that involve large displacements such as that of ocean risers, sinking of a ship, or the free-flight of an insect, it is cumbersome to utilize a single computational grid and move the body of interest. In this work, we discuss a high-fidelity approach based on overset or overlapping grids which overcomes the necessity of using a single computational grid. The overset library is parallelized using the Message Passing Interface (MPI and Pthreads and is linked dynamically to OpenFOAM. Computational results are presented to demonstrate the potential of this method for simulating problems with large displacements.

  6. Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors

    CERN Document Server

    Bakosi, J; Lowrie, R B; Pritchett-Sheats, L A; Nourgaliev, R R

    2013-01-01

    The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3x3 and 5x5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carried out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the single-phase incompressible Navier-Stokes equations. The simulations explicitly resolve the la...

  7. 3D Staggered-Grid Finite-Difference Simulation of Acoustic Waves in Turbulent Moving Media

    Science.gov (United States)

    Symons, N. P.; Aldridge, D. F.; Marlin, D.; Wilson, D. K.; Sullivan, P.; Ostashev, V.

    2003-12-01

    Acoustic wave propagation in a three-dimensional heterogeneous moving atmosphere is accurately simulated with a numerical algorithm recently developed under the DOD Common High Performance Computing Software Support Initiative (CHSSI). Sound waves within such a dynamic environment are mathematically described by a set of four, coupled, first-order partial differential equations governing small-amplitude fluctuations in pressure and particle velocity. The system is rigorously derived from fundamental principles of continuum mechanics, ideal-fluid constitutive relations, and reasonable assumptions that the ambient atmospheric motion is adiabatic and divergence-free. An explicit, time-domain, finite-difference (FD) numerical scheme is used to solve the system for both pressure and particle velocity wavefields. The atmosphere is characterized by 3D gridded models of sound speed, mass density, and the three components of the wind velocity vector. Dependent variables are stored on staggered spatial and temporal grids, and centered FD operators possess 2nd-order and 4th-order space/time accuracy. Accurate sound wave simulation is achieved provided grid intervals are chosen appropriately. The gridding must be fine enough to reduce numerical dispersion artifacts to an acceptable level and maintain stability. The algorithm is designed to execute on parallel computational platforms by utilizing a spatial domain-decomposition strategy. Currently, the algorithm has been validated on four different computational platforms, and parallel scalability of approximately 85% has been demonstrated. Comparisons with analytic solutions for uniform and vertically stratified wind models indicate that the FD algorithm generates accurate results with either a vanishing pressure or vanishing vertical-particle velocity boundary condition. Simulations are performed using a kinematic turbulence wind profile developed with the quasi-wavelet method. In addition, preliminary results are presented

  8. A Grid-Based Cyber Infrastructure for High Performance Chemical Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Khadka Prashant

    2008-10-01

    Full Text Available Chemical dynamics simulation is an effective means to study atomic level motions of molecules, collections of molecules, liquids, surfaces, interfaces of materials, and chemical reactions. To make chemical dynamics simulations globally accessible to a broad range of users, recently a cyber infrastructure was developed that provides an online portal to VENUS, a popular chemical dynamics simulation program package, to allow people to submit simulation jobs that will be executed on the web server machine. In this paper, we report new developments of the cyber infrastructure for the improvement of its quality of service by dispatching the submitted simulations jobs from the web server machine onto a cluster of workstations for execution, and by adding an animation tool, which is optimized for animating the simulation results. The separation of the server machine from the simulation-running machine improves the service quality by increasing the capacity to serve more requests simultaneously with even reduced web response time, and allows the execution of large scale, time-consuming simulation jobs on the powerful workstation cluster. With the addition of an animation tool, the cyber infrastructure automatically converts, upon the selection of the user, some simulation results into an animation file that can be viewed on usual web browsers without requiring installation of any special software on the user computer. Since animation is essential for understanding the results of chemical dynamics simulations, this animation capacity provides a better way for understanding simulation details of the chemical dynamics. By combining computing resources at locations under different administrative controls, this cyber infrastructure constitutes a grid environment providing physically and administratively distributed functionalities through a single easy-to-use online portal

  9. Closures for Course-Grid Simulation of Fluidized Gas-Particle Flows

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran Sundaresan

    2010-02-14

    Gas-particle flows in fluidized beds and riser reactors are inherently unstable, and they manifest fluctuations over a wide range of length and time scales. Two-fluid models for such flows reveal unstable modes whose length scale is as small as ten particle diameters. Yet, because of limited computational resources, gas-particle flows in large fluidized beds are invariably simulated by solving discretized versions of the two-fluid model equations over a coarse spatial grid. Such coarse-grid simulations do not resolve the small-scale spatial structures which are known to affect the macroscale flow structures both qualitatively and quantitatively. Thus there is a need to develop filtered two-fluid models which are suitable for coarse-grid simulations and capturing the effect of the small-scale structures through closures in terms of the filtered variables. The overall objective of the project is to develop validated closures for filtered two-fluid models for gas-particle flows, with the transport gasifier as a primary, motivating example. In this project, highly resolved three-dimensional simulations of a kinetic theory based two-fluid model for gas-particle flows have been performed and the statistical information on structures in the 100-1000 particle diameters length scale has been extracted. Based on these results, closures for filtered two-fluid models have been constructed. The filtered model equations and closures have been validated against experimental data and the results obtained in highly resolved simulations of gas-particle flows. The proposed project enables more accurate simulations of not only the transport gasifier, but also many other non-reacting and reacting gas-particle flows in a variety of chemical reactors. The results of this study are in the form of closures which can readily be incorporated into existing multi-phase flow codes such as MFIX (www.mfix.org). Therefore, the benefits of this study can be realized quickly. The training provided

  10. Real-Time Dynamic Simulation of Korean Power Grid for Frequency Regulation Control by MW Battery Energy Storage System

    Directory of Open Access Journals (Sweden)

    Tae-Hwan Jin

    2016-12-01

    Full Text Available The aim of this study was to develop a real-time dynamic simulator of a power grid with power plant and battery model. The simulator was used to investigate the frequency control characteristics of a megawatt-scale high-capacity energy storage system connected to the electric power grid. In this study, a lithium-ion secondary battery was chosen as one of the batteries for a grid-connected model. The dynamics of the model was analysed in both steady and transient states. The frequency control system of the battery model plays a role in regulating the grid frequency by controlling the power of energy storage systems according to process variables and grid frequencies. The power grid model based on the current power network of South Korea, included power plants, substations and power demands. The power supply is classified by the type of turbine generator as thermal, nuclear, hydro power, pumped power storage, combined power plants, and batteries, including high-capacity energy storage systems rated for a maximum of 500 MW. This study deals with an installed capacity of 87.17 GW and peak load of 77.30 GW in the Korean power grid. For 24 hours of operation, the maximum and minimum power outputs were simulated as 61.59 GW and 46.32 GW, respectively. The commercialized real-time dynamic simulation software ProTRAX was used. The simulation was conducted to observe the operation characteristics of the frequency control system during a breakdown of power plants, as well as under governor-free operation, auto generation control operation, and with the battery energy storage system connected. The results show that the model is valid for each power plant breakdown simulation. They also confirm that the output power and frequency controls of the battery operated well during simulations.

  11. A Comparison of Grid-based and SPH Binary Mass-transfer and Merger Simulations

    Science.gov (United States)

    Motl, Patrick M.; Frank, Juhan; Staff, Jan; Clayton, Geoffrey C.; Fryer, Christopher L.; Even, Wesley; Diehl, Steven; Tohline, Joel E.

    2017-04-01

    There is currently a great amount of interest in the outcomes and astrophysical implications of mergers of double degenerate binaries. In a commonly adopted approximation, the components of such binaries are represented by polytropes with an index of n = 3/2. We present detailed comparisons of stellar mass-transfer and merger simulations of polytropic binaries that have been carried out using two very different numerical algorithms—a finite-volume “grid” code and a smoothed-particle hydrodynamics (SPH) code. We find that there is agreement in both the ultimate outcomes of the evolutions and the intermediate stages if the initial conditions for each code are chosen to match as closely as possible. We find that even with closely matching initial setups, the time it takes to reach a concordant evolution differs between the two codes because the initial depth of contact cannot be matched exactly. There is a general tendency for SPH to yield higher mass transfer rates and faster evolution to the final outcome. We also present comparisons of simulations calculated from two different energy equations: in one series, we assume a polytropic equation of state and in the other series an ideal gas equation of state. In the latter series of simulations, an atmosphere forms around the accretor, which can exchange angular momentum and cause a more rapid loss of orbital angular momentum. In the simulations presented here, the effect of the ideal equation of state is to de-stabilize the binary in both SPH and grid simulations, but the effect is more pronounced in the grid code.

  12. Effective grid-dependent dispersion coefficient for conservative and reactive transport simulations in heterogeneous porous media

    Science.gov (United States)

    Cortinez, J. M.; Valocchi, A. J.; Herrera, P. A.

    2013-12-01

    Because of the finite size of numerical grids, it is very difficult to correctly account for processes that occur at different spatial scales to accurately simulate the migration of conservative and reactive compounds dissolved in groundwater. In one hand, transport processes in heterogeneous porous media are controlled by local-scale dispersion associated to transport processes at the pore-scale. On the other hand, variations of velocity at the continuum- or Darcy-scale produce spreading of the contaminant plume, which is referred to as macro-dispersion. Furthermore, under some conditions both effects interact, so that spreading may enhance the action of local-scale dispersion resulting in higher mixing, dilution and reaction rates. Traditionally, transport processes at different spatial scales have been included in numerical simulations by using a single dispersion coefficient. This approach implicitly assumes that the separate effects of local-dispersion and macro-dispersion can be added and represented by a unique effective dispersion coefficient. Moreover, the selection of the effective dispersion coefficient for numerical simulations usually do not consider the filtering effect of the grid size over the small-scale flow features. We have developed a multi-scale Lagragian numerical method that allows using two different dispersion coefficients to represent local- and macro-scale dispersion. This technique considers fluid particles that carry solute mass and whose locations evolve according to a deterministic component given by the grid-scale velocity and a stochastic component that corresponds to a block-effective macro-dispersion coefficient. Mass transfer between particles due to local-scale dispersion is approximated by a meshless method. We use our model to test under which transport conditions the combined effect of local- and macro-dispersion are additive and can be represented by a single effective dispersion coefficient. We also demonstrate that for

  13. RELAP5 model to simulate the thermal-hydraulic effects of grid spacers and cladding rupture during reflood

    Energy Technology Data Exchange (ETDEWEB)

    Nithianandan, C.K.; Klingenfus, J.A.; Reilly, S.S. [B& W Nuclear Technologies, Lynchburg, VA (United States)

    1995-09-01

    Droplet breakup at spacer grids and a cladding swelled and ruptured locations plays an important role in the cooling of nuclear fuel rods during the reflooding period of a loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR). During the reflood phase, a spacer grid affects the thermal-hydraulic system behavior through increased turbulence, droplet breakup due to impact on grid straps, grid rewetting, and liquid holdup due to grid form losses. Recently, models to simulate spacer grid effects and blockage and rupture effects on system thermal hydraulics were added to the B&W Nuclear Technologies (BWNT) version of the RELAP5/MOD2 computer code. Several FLECHT-SEASET forced reflood tests, CCTF Tests C1-19 and C2-6, SCTF Test S3-15, and G2 Test 561 were simulated using RELAP5/MOD2-B&W to verify the applicability of the model at the cladding swelled and rupture locations. The results demonstrate the importance of modeling the thermal-hydraulic effects due to grids, and clad swelling and rupture to correctly predict the clad temperature response during the reflood phase of large break LOCA. The RELAP5 models and the test results are described in this paper.

  14. Evaluation of high grid strip densities based on the moiré artifact analysis for quality assurance: Simulation and experiment

    Science.gov (United States)

    Je, U. K.; Park, C. K.; Lim, H. W.; Cho, H. S.; Lee, D. Y.; Lee, H. W.; Kim, K. S.; Park, S. Y.; Kim, G. A.; Kang, S. Y.; Park, J. E.; Kim, W. S.; Jeon, D. H.; Woo, T. H.

    2017-09-01

    We have recently developed precise x-ray grids having strip densities in the range of 100 - 250 lines/inch by adopting the precision sawing process and carbon interspace material for the demands of specific x-ray imaging techniques. However, quality assurance in the grid manufacturing has not yet satisfactorily conducted because grid strips of a high strip density are often invisible through an x-ray nondestructive testing with a flat-panel detector of an ordinary pixel resolution (>100 μm). In this work, we propose a useful method to evaluate actual grid strip densities over the Nyquist sampling rate based on the moiré artifact analysis. We performed a systematic simulation and experiment with several sample grids and a detector having a 143- μm pixel resolution to verify the proposed quality assurance method. According to our results, the relative differences between the nominal and the evaluated grid strip densities were within 0.2% and 1.8% in the simulation and experiment, respectively, which demonstrates that the proposed method is viable with an ordinary detector having a moderate pixel resolution for quality assurance in grid manufacturing.

  15. Framework for Grid Manufacturing

    Institute of Scientific and Technical Information of China (English)

    陈笠; 邓宏; 邓倩妮; 吴振宇

    2004-01-01

    With the development of networked manufacturing, it is more and more imminent to solve problems caused by inherent limitations of network technology, such as heterogeneity, collaboration collision, and decentralized control.This paper presents a framework for grid manufacturing, which neatly combines grid technology with the infrastructure of advanced manufacturing technology.The paper studies grid-oriented knowledge description and acquisition, and constructs a distributed knowledge grid model.The paper also deals with the protocol of node description in collaborative design, and describes a distributed collaborative design model.The protocol and node technology leads to a collaborative production model for grid manufacturing.The framework for grid manufacturing offers an effective and feasible solution for the problems of networked manufacturing.The grid manufacturing will become an advanced distributed manufacturing model and promote the development of advanced manufacturing technologies.

  16. Thread Group Multithreading: Accelerating the Computation of an Agent-Based Power System Modeling and Simulation Tool -- C GridLAB-D

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Shuangshuang; Chassin, David P.

    2014-01-06

    GridLAB-DTM is an open source next generation agent-based smart-grid simulator that provides unprecedented capability to model the performance of smart grid technologies. Over the past few years, GridLAB-D has been used to conduct important analyses of smart grid concepts, but it is still quite limited by its computational performance. In order to break through the performance bottleneck to meet the need for large scale power grid simulations, we develop a thread group mechanism to implement highly granular multithreaded computation in GridLAB-D. We achieve close to linear speedups on multithreading version compared against the single-thread version of the same code running on general purpose multi-core commodity for a benchmark simple house model. The performance of the multithreading code shows favorable scalability properties and resource utilization, and much shorter execution time for large-scale power grid simulations.

  17. Snap, Crackle, Pop: sub-grid supernova feedback in AMR simulations of disk galaxies

    CERN Document Server

    Rosdahl, Joakim; Dubois, Yohan; Kimm, Taysun; Teyssier, Romain

    2016-01-01

    We compare 5 sub-grid models for supernova (SN) feedback in adaptive mesh refinement (AMR) simulations of isolated dwarf and L-star disk galaxies with 20-40 pc resolution. The models are thermal dump, stochastic thermal, 'mechanical' (injecting energy or momentum depending on the resolution), kinetic, and delayed cooling feedback. We focus on the ability of each model to suppress star formation and generate outflows. Our highest-resolution runs marginally resolve the adiabatic phase of the feedback events, which correspond to 40 SN explosions, and the first three models yield nearly identical results, possibly indicating that kinetic and delayed cooling feedback converge to wrong results. At lower resolution all models differ, with thermal dump feedback becoming inefficient. Thermal dump, stochastic, and mechanical feedback generate multiphase outflows with mass loading factors $\\beta \\ll 1$, which is much lower than observed. For the case of stochastic feedback we compare to published SPH simulations, and fi...

  18. Advances in time-domain electromagnetic simulation capabilities through the use of overset grids and massively parallel computing

    Science.gov (United States)

    Blake, Douglas Clifton

    A new methodology is presented for conducting numerical simulations of electromagnetic scattering and wave-propagation phenomena on massively parallel computing platforms. A process is constructed which is rooted in the Finite-Volume Time-Domain (FVTD) technique to create a simulation capability that is both versatile and practical. In terms of versatility, the method is platform independent, is easily modifiable, and is capable of solving a large number of problems with no alterations. In terms of practicality, the method is sophisticated enough to solve problems of engineering significance and is not limited to mere academic exercises. In order to achieve this capability, techniques are integrated from several scientific disciplines including computational fluid dynamics, computational electromagnetics, and parallel computing. The end result is the first FVTD solver capable of utilizing the highly flexible overset-gridding process in a distributed-memory computing environment. In the process of creating this capability, work is accomplished to conduct the first study designed to quantify the effects of domain-decomposition dimensionality on the parallel performance of hyperbolic partial differential equations solvers; to develop a new method of partitioning a computational domain comprised of overset grids; and to provide the first detailed assessment of the applicability of overset grids to the field of computational electromagnetics. Using these new methods and capabilities, results from a large number of wave propagation and scattering simulations are presented. The overset-grid FVTD algorithm is demonstrated to produce results of comparable accuracy to single-grid simulations while simultaneously shortening the grid-generation process and increasing the flexibility and utility of the FVTD technique. Furthermore, the new domain-decomposition approaches developed for overset grids are shown to be capable of producing partitions that are better load balanced and

  19. An Investigation of University Students' Collaborative Inquiry Learning Behaviors in an Augmented Reality Simulation and a Traditional Simulation

    Science.gov (United States)

    Wang, Hung-Yuan; Duh, Henry Been-Lirn; Li, Nai; Lin, Tzung-Jin; Tsai, Chin-Chung

    2014-01-01

    The purpose of this study is to investigate and compare students' collaborative inquiry learning behaviors and their behavior patterns in an augmented reality (AR) simulation system and a traditional 2D simulation system. Their inquiry and discussion processes were analyzed by content analysis and lag sequential analysis (LSA). Forty…

  20. Adaptive grid-based confidence assessment for synthetic optoelectronic images by Physical Reasonable Infrared Scene Simulation Engine (PRISSE)

    Science.gov (United States)

    Wu, Xin; Sun, Hao; Ma, Xiangchao; Wang, Yucheng; Han, Yiping

    2017-09-01

    Like visible spectrum, synthetic infrared scenes reflect the invisible world of infrared features. Propagation of a typical infrared radiation involves a variety of sources of different sizes, shapes, intensities, roughness, temperature, etc., all of which would impose impacts on the fidelity of the synthetic images. Assessing the confidence of a synthetic infrared scene is therefore not so intuitive as evaluating the quality of a visible image. An adaptive grid-based method is proposed in this paper for similarity assessments between synthetic infrared images and the corresponding real infrared images, which is on a grid-by-grid basis. Different from many traditional methods, each grid in our work is weighted by a value that is simulated by a 2D Gamma distribution. Introducing adaptive grids and exerting a weighting value on each grid are the aspects of our method. To investigate the effectiveness of our method, an experiment was conducted for taking real mid-wavelength infrared (MWIR) images, and the corresponding synthetic MWIR images were simulated by Physical Reasonable Infrared Scene Simulation Engine (PRISSE). The confidence of similarity assessments evaluated by our method is then compared to some popularly-used traditional assessment methods.

  1. Agent-based simulation of building evacuation using a grid graph-based model

    Science.gov (United States)

    Tan, L.; Lin, H.; Hu, M.; Che, W.

    2014-02-01

    Shifting from macroscope models to microscope models, the agent-based approach has been widely used to model crowd evacuation as more attentions are paid on individualized behaviour. Since indoor evacuation behaviour is closely related to spatial features of the building, effective representation of indoor space is essential for the simulation of building evacuation. The traditional cell-based representation has limitations in reflecting spatial structure and is not suitable for topology analysis. Aiming at incorporating powerful topology analysis functions of GIS to facilitate agent-based simulation of building evacuation, we used a grid graph-based model in this study to represent the indoor space. Such model allows us to establish an evacuation network at a micro level. Potential escape routes from each node thus could be analysed through GIS functions of network analysis considering both the spatial structure and route capacity. This would better support agent-based modelling of evacuees' behaviour including route choice and local movements. As a case study, we conducted a simulation of emergency evacuation from the second floor of an official building using Agent Analyst as the simulation platform. The results demonstrate the feasibility of the proposed method, as well as the potential of GIS in visualizing and analysing simulation results.

  2. PMEL contributions to the collaboration: SCALING THE EARTH SYSTEM GRID TO PETASCALE DATA for the DOE SciDACs Earth System Grid Center for Enabling Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Hankin, Steve

    2012-06-01

    Drawing to a close after five years of funding from DOE's ASCR and BER program offices, the SciDAC-2 project called the Earth System Grid (ESG) Center for Enabling Technologies has successfully established a new capability for serving data from distributed centers. The system enables users to access, analyze, and visualize data using a globally federated collection of networks, computers and software. The ESG software now known as the Earth System Grid Federation (ESGF) has attracted a broad developer base and has been widely adopted so that it is now being utilized in serving the most comprehensive multi-model climate data sets in the world. The system is used to support international climate model intercomparison activities as well as high profile U.S. DOE, NOAA, NASA, and NSF projects. It currently provides more than 25,000 users access to more than half a petabyte of climate data (from models and from observations) and has enabled over a 1,000 scientific publications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Udhay Ravishankar; Milos manic

    2013-08-01

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

  4. Reducing numerical costs for core wide nuclear reactor CFD simulations by the Coarse-Grid-CFD

    Science.gov (United States)

    Viellieber, Mathias; Class, Andreas G.

    2013-11-01

    Traditionally complete nuclear reactor core simulations are performed with subchannel analysis codes, that rely on experimental and empirical input. The Coarse-Grid-CFD (CGCFD) intends to replace the experimental or empirical input with CFD data. The reactor core consists of repetitive flow patterns, allowing the general approach of creating a parametrized model for one segment and composing many of those to obtain the entire reactor simulation. The method is based on a detailed and well-resolved CFD simulation of one representative segment. From this simulation we extract so-called parametrized volumetric forces which close, an otherwise strongly under resolved, coarsely-meshed model of a complete reactor setup. While the formulation so far accounts for forces created internally in the fluid others e.g. obstruction and flow deviation through spacers and wire wraps, still need to be accounted for if the geometric details are not represented in the coarse mesh. These are modelled with an Anisotropic Porosity Formulation (APF). This work focuses on the application of the CGCFD to a complete reactor core setup and the accomplishment of the parametrization of the volumetric forces.

  5. SWAT use of gridded observations for simulating runoff - a Vietnam river basin study

    Science.gov (United States)

    Vu, M. T.; Raghavan, S. V.; Liong, S. Y.

    2012-08-01

    Many research studies that focus on basin hydrology have applied the SWAT model using station data to simulate runoff. But over regions lacking robust station data, there is a problem of applying the model to study the hydrological responses. For some countries and remote areas, the rainfall data availability might be a constraint due to many different reasons such as lacking of technology, war time and financial limitation that lead to difficulty in constructing the runoff data. To overcome such a limitation, this research study uses some of the available globally gridded high resolution precipitation datasets to simulate runoff. Five popular gridded observation precipitation datasets: (1) Asian Precipitation Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources (APHRODITE), (2) Tropical Rainfall Measuring Mission (TRMM), (3) Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIANN), (4) Global Precipitation Climatology Project (GPCP), (5) a modified version of Global Historical Climatology Network (GHCN2) and one reanalysis dataset, National Centers for Environment Prediction/National Center for Atmospheric Research (NCEP/NCAR) are used to simulate runoff over the Dak Bla river (a small tributary of the Mekong River) in Vietnam. Wherever possible, available station data are also used for comparison. Bilinear interpolation of these gridded datasets is used to input the precipitation data at the closest grid points to the station locations. Sensitivity Analysis and Auto-calibration are performed for the SWAT model. The Nash-Sutcliffe Efficiency (NSE) and Coefficient of Determination (R2) indices are used to benchmark the model performance. Results indicate that the APHRODITE dataset performed very well on a daily scale simulation of discharge having a good NSE of 0.54 and R2 of 0.55, when compared to the discharge simulation using station data (0.68 and 0.71). The GPCP proved to be the

  6. SWAT use of gridded observations for simulating runoff – a Vietnam river basin study

    Directory of Open Access Journals (Sweden)

    M. T. Vu

    2012-08-01

    Full Text Available Many research studies that focus on basin hydrology have applied the SWAT model using station data to simulate runoff. But over regions lacking robust station data, there is a problem of applying the model to study the hydrological responses. For some countries and remote areas, the rainfall data availability might be a constraint due to many different reasons such as lacking of technology, war time and financial limitation that lead to difficulty in constructing the runoff data. To overcome such a limitation, this research study uses some of the available globally gridded high resolution precipitation datasets to simulate runoff. Five popular gridded observation precipitation datasets: (1 Asian Precipitation Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources (APHRODITE, (2 Tropical Rainfall Measuring Mission (TRMM, (3 Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIANN, (4 Global Precipitation Climatology Project (GPCP, (5 a modified version of Global Historical Climatology Network (GHCN2 and one reanalysis dataset, National Centers for Environment Prediction/National Center for Atmospheric Research (NCEP/NCAR are used to simulate runoff over the Dak Bla river (a small tributary of the Mekong River in Vietnam. Wherever possible, available station data are also used for comparison. Bilinear interpolation of these gridded datasets is used to input the precipitation data at the closest grid points to the station locations. Sensitivity Analysis and Auto-calibration are performed for the SWAT model. The Nash-Sutcliffe Efficiency (NSE and Coefficient of Determination (R2 indices are used to benchmark the model performance. Results indicate that the APHRODITE dataset performed very well on a daily scale simulation of discharge having a good NSE of 0.54 and R2 of 0.55, when compared to the discharge simulation using station data (0

  7. COARSE-GRID SIMULATION OF REACTING AND NON-REACTING GAS-PARTICLE FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran Sundaresan

    2004-03-01

    The principal goal of this project, funded under the ''DOE Vision 21 Virtual Demonstration Initiative'' is virtual demonstration of circulating fluidized bed performance. We had proposed a ''virtual demonstration tool'', which is based on the open-domain CFD code MFIX. The principal challenge funded through this grant is to devise and implement in this CFD code sound physical models for the rheological characteristics of the gas-particle mixtures. Within the past year, which was the third year of the project, we have made the following specific advances. (a) We have completed a study of the impact of sub-grid models of different levels of detail on the results obtained in coarse-grid simulations of gas-particle flow. (b) We have also completed a study of a model problem to understand the effect of wall friction, which was proved in our earlier work to be very important for stable operation of standpipes in a circulating fluidized bed circuit. These are described in a greater detail in this report.

  8. The performance test of anti-scattering x-ray grid with inclined shielding material by MCNP code simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jun Woo; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2016-06-15

    The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination.

  9. Electric field distribution and simulation of avalanche formation due to the passage of heavy ions in a parallel grid avalanche counter

    Indian Academy of Sciences (India)

    D Kanjilal; S Saha

    2009-05-01

    Electric field distributions and their role in the formation of avalanche due to the passage of heavy ions in parallel grid avalanche type wire chamber detectors are evaluated using a Monte Carlo simulation. The relative merits and demerits of parallel and crossed wire grid configurations are studied. It is found that the crossed grid geometry has marginally higher gain at larger electric fields close to the avalanche region. The spatial uniformity of response in the two wire grid configurations is also compared.

  10. A Software Package Using a Mesh-grid Method for Simulating HPGe Detector Efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Jackman

    2009-10-01

    Traditional ways of determining the absolute full-energy peak efficiencies of high-purity germanium (HPGe) detectors are often time consuming, cost prohibitive, or not feasible. A software package, KMESS (Kevin’s Mesh Efficiency Simulator Software), was developed to assist in predicting these efficiencies. It uses a semiempirical mesh-grid method and works for arbitrary source shapes and counting geometries. The model assumes that any gamma-ray source shape can be treated as a large enough collection of point sources. The code is readily adaptable, has a web-based graphical front-end, and could easily be coupled to a 3D scanner. As will be shown, this software can estimate absolute full-energy peak efficiencies with good accuracy in reasonable computation times. It has applications to the field of gamma-ray spectroscopy because it is a quick and accurate way to assist in performing quantitative analyses using HPGe detectors.

  11. A software package using a mesh-grid method for simulating HPGe detector efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Gritzo, Russell E [Los Alamos National Laboratory; Jackman, Kevin R [REMOTE SENSING LAB; Biegalski, Steven R [UT AUSTIN

    2009-01-01

    Traditional ways of determining the absolute full-energy peak efficiencies of high-purity germanium (HPGe) detectors are often time consuming, cost prohibitive, or not feasible. A software package, KMESS (Kevin's Mesh Efficiency Simulator Software), was developed to assist in predicting these efficiencies. It uses a semiempirical mesh-grid method and works for arbitrary source shapes and counting geometries. The model assumes that any gamma-ray source shape can be treated as a large enough collection of point sources. The code is readily adaptable, has a web-based graphical front-end. and could easily be coupled to a 3D scanner. As will be shown. this software can estimate absolute full-energy peak efficiencies with good accuracy in reasonable computation times. It has applications to the field of gamma-ray spectroscopy because it is a quick and accurate way to assist in performing quantitative analyses using HPGe detectors.

  12. 3D Myocardial Contraction Imaging Based on Dynamic Grid Interpolation: Theory and Simulation Analysis

    Science.gov (United States)

    Bu, Shuhui; Shiina, Tsuyoshi; Yamakawa, Makoto; Takizawa, Hotaka

    Accurate assessment of local myocardial contraction is important for diagnosis of ischemic heart disease, because decreases of myocardial motion often appear in the early stages of the disease. Three-dimensional (3-D) assessment of the stiffness distribution is required for accurate diagnosis of ischemic heart disease. Since myocardium motion occurs radially within the left ventricle wall and the ultrasound beam propagates axially, conventional approaches, such as tissue Doppler imaging and strain-rate imaging techniques, cannot provide us with enough quantitative information about local myocardial contraction. In order to resolve this problem, we propose a novel myocardial contraction imaging system which utilizes the weighted phase gradient method, the extended combined autocorrelation method, and the dynamic grid interpolation (DGI) method. From the simulation results, we conclude that the strain image's accuracy and contrast have been improved by the proposed method.

  13. A GPU-enabled Finite Volume solver for global magnetospheric simulations on unstructured grids

    Science.gov (United States)

    Lani, Andrea; Yalim, Mehmet Sarp; Poedts, Stefaan

    2014-10-01

    This paper describes an ideal Magnetohydrodynamics (MHD) solver for global magnetospheric simulations based on a B1 +B0 splitting approach, which has been implemented within the COOLFluiD platform and adapted to run on modern heterogeneous architectures featuring General Purpose Graphical Processing Units (GPGPUs). The code is based on a state-of-the-art Finite Volume discretization for unstructured grids and either explicit or implicit time integration, suitable for both steady and time accurate problems. Innovative object-oriented design and coding techniques mixing C++ and CUDA are discussed. Performance results of the modified code on single and multiple processors are presented and compared with those provided by the original solver.

  14. A dynamic mesh refinement technique for Lattice Boltzmann simulations on octree-like grids

    KAUST Repository

    Neumann, Philipp

    2012-04-27

    In this contribution, we present our new adaptive Lattice Boltzmann implementation within the Peano framework, with special focus on nanoscale particle transport problems. With the continuum hypothesis not holding anymore on these small scales, new physical effects - such as Brownian fluctuations - need to be incorporated. We explain the overall layout of the application, including memory layout and access, and shortly review the adaptive algorithm. The scheme is validated by different benchmark computations in two and three dimensions. An extension to dynamically changing grids and a spatially adaptive approach to fluctuating hydrodynamics, allowing for the thermalisation of the fluid in particular regions of interest, is proposed. Both dynamic adaptivity and adaptive fluctuating hydrodynamics are validated separately in simulations of particle transport problems. The application of this scheme to an oscillating particle in a nanopore illustrates the importance of Brownian fluctuations in such setups. © 2012 Springer-Verlag.

  15. A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

    CERN Document Server

    Klassen, Mikhail; Pudritz, Ralph E; Peters, Thomas; Banerjee, Robi; Buntemeyer, Lars

    2014-01-01

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodynamics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion (FLD) solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calc...

  16. Simulation modeling of cloud computing for smart grid using CloudSim

    Directory of Open Access Journals (Sweden)

    Sandeep Mehmi

    2017-05-01

    Full Text Available In this paper a smart grid cloud has been simulated using CloudSim. Various parameters like number of virtual machines (VM, VM Image size, VM RAM, VM bandwidth, cloudlet length, and their effect on cost and cloudlet completion time in time-shared and space-shared resource allocation policy have been studied. As the number of cloudlets increased from 68 to 178, greater number of cloudlets completed their execution with high cloudlet completion time in time-shared allocation policy as compared to space-shared allocation policy. Similar trend has been observed when VM bandwidth is increased from 1 Gbps to 10 Gbps and VM RAM is increased from 512 MB to 5120 MB. The cost of processing increased linearly with respect to increase in number of VMs, VM Image size and cloudlet length.

  17. Simulation of Unsteady Flows Using an Unstructured Navier-Stokes Solver on Moving and Stationary Grids

    Science.gov (United States)

    Biedron, Robert T.; Vatsa, Veer N.; Atkins, Harold L.

    2005-01-01

    We apply an unsteady Reynolds-averaged Navier-Stokes (URANS) solver for unstructured grids to unsteady flows on moving and stationary grids. Example problems considered are relevant to active flow control and stability and control. Computational results are presented using the Spalart-Allmaras turbulence model and are compared to experimental data. The effect of grid and time-step refinement are examined.

  18. Interdisciplinary Collaboration through Designing 3D Simulation Case Studies

    CERN Document Server

    Bai, Xin; 10.5121/ijma.2011.3109

    2011-01-01

    Interdisciplinary collaboration is essential for the advance of research. As domain subjects become more and more specialized, researchers need to cross disciplines for insights from peers in other areas to have a broader and deeper understand of a topic at micro- and macro-levels. We developed a 3D virtual learning environment that served as a platform for faculty to plan curriculum, share educational beliefs, and conduct cross-discipline research for effective learning. Based upon the scripts designed by faculty from five disciplines, virtual doctors, nurses, or patients interact in a 3D virtual hospital. The teaching vignettes were then converted to video clips, allowing users to view, pause, replay, or comment on the videos individually or in groups. Unlike many existing platforms, we anticipated a value-added by adding a social networking capacity to this virtual environment. The focus of this paper is on the cost-efficiency and system design of the virtual learning environment.

  19. Effect of computational grid on accurate prediction of a wind turbine rotor using delayed detached-eddy simulations

    Energy Technology Data Exchange (ETDEWEB)

    Bangga, Galih; Weihing, Pascal; Lutz, Thorsten; Krämer, Ewald [University of Stuttgart, Stuttgart (Germany)

    2017-05-15

    The present study focuses on the impact of grid for accurate prediction of the MEXICO rotor under stalled conditions. Two different blade mesh topologies, O and C-H meshes, and two different grid resolutions are tested for several time step sizes. The simulations are carried out using Delayed detached-eddy simulation (DDES) with two eddy viscosity RANS turbulence models, namely Spalart- Allmaras (SA) and Menter Shear stress transport (SST) k-ω. A high order spatial discretization, WENO (Weighted essentially non- oscillatory) scheme, is used in these computations. The results are validated against measurement data with regards to the sectional loads and the chordwise pressure distributions. The C-H mesh topology is observed to give the best results employing the SST k-ω turbulence model, but the computational cost is more expensive as the grid contains a wake block that increases the number of cells.

  20. The National Center for Collaboration in Medical Modeling and Simulation

    Science.gov (United States)

    2005-05-01

    4 T ask 2 - T echnology D evelopm ent ...................................................................... 9 Task 3 - Simulators and Curriculum...offices, clinics, and even in mobile blood vehicles. Further, there are a number of concerns with respect to patient safety. According to Mishori... mobilization exposes more personnel to novel pathogens or if the stress of war down regulates immune function. Table 7. Similarity of ICD Profiles for

  1. DISTRIBUTED GRID-CONNECTED PHOTOVOLTAIC POWER SYSTEM EMISSION OFFSET ASSESSMENT: STATISTICAL TEST OF SIMULATED- AND MEASURED-BASED DATA

    Science.gov (United States)

    This study assessed the pollutant emission offset potential of distributed grid-connected photovoltaic (PV) power systems. Computer-simulated performance results were utilized for 211 PV systems located across the U.S. The PV systems' monthly electrical energy outputs were based ...

  2. Validation of a Switching Operation in the External Grid of Gunfleet Sand Offshore Wind Farm by Means of EMT Simulations

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Okholm, J.; Holbøll, Joachim

    2011-01-01

    This paper presents the voltage signals occurring during a switching operation recorded in the external grid of Gunfleet Sands Offshore Wind Farm recorded with an Elspec measurement system. The measurements are compared to electromagnetic (EMT) simulations for validation of the wind farm model...

  3. Grid connected integrated community energy system. Phase II: final state 2 report. Cost benefit analysis, operating costs and computer simulation

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-22

    A grid-connected Integrated Community Energy System (ICES) with a coal-burning power plant located on the University of Minnesota campus is planned. The cost benefit analysis performed for this ICES, the cost accounting methods used, and a computer simulation of the operation of the power plant are described. (LCL)

  4. An Efficient and Robust Method for Lagrangian Magnetic Particle Tracking in Fluid Flow Simulations on Unstructured Grids

    NARCIS (Netherlands)

    Cohen Stuart, D.C.; Kleijn, C.R.; Kenjeres, S.

    2010-01-01

    In this paper we report on a newly developed particle tracking scheme for fluid flow simulations on 3D unstructured grids, aiming to provide detailed insights in the particle behaviour in complex geometries. A possible field of applications is the Magnetic Drug Targeting (MDT) technique, on which th

  5. Simulation of a Periodic Jet in a Crossflow with a RANS Solver Using an Unstructured Grid

    Science.gov (United States)

    Atkins, H. L.

    2007-01-01

    A second-order unstructured-grid code, developed and used primarily for steady aerodynamic simulations, is applied to the synthetic jet in a cross flow. The code, FUN3D, is a vertex-centered finite-volume method originally developed by Anderson[1, 2], and is currently supported by members of the Fast Adaptive Aerospace Tools team at NASA Langley. Used primarily for design[3] and analysis[4] of steady aerodynamic configurations, FUN3D incorporates a discrete adjoint capability, and supports parallel computations using MPI. A detailed description of the FUN3D code can be found in the references given above. The code is under continuous development and contains a variety of flux splitting algorithms for the inviscid terms, two methods for computing gradients, several turbulence models, and several solution methodologies; all in varying states of development. Only the most robust and reliable components, based on experiences with steady aerodynamic simulations, were employed in this work. As applied in this work, FUN3D solves the Reynolds averaged Navier-Stokes equations using the one equation turbulence model of Spalart and Allmaras[5]. The spatial discretization is formed on unstructured meshes using a vertex-centered approach. The inviscid terms are evaluated by a flux-difference splitting formulation using least-squares reconstruction and Roe-type approximate Riemann fluxes. Green-Gauss gradient evaluations are used for viscous and turbulence modeling terms. The discrete spatial operator is combined with a backward time operator which is then solved iteratively using point or line Gauss-Seidel and local time stepping in a pseudo time. For steady flows, the physical time step is set to infinity and the pseudo time step is ramped up with the iteration count. A second-order backward in time operator is used for time accurate flows with 20 to 50 steps in the pseudo time applied at each physical time step. For this effort, FUN3D was modified to support spatially varying

  6. Applying 2D Bias Correction Method to Gridded Simulations of Precipitation and Temperature over Southeastern South America.

    Science.gov (United States)

    Piani, C.; Montroull, N.; Saurral, R. I.

    2014-12-01

    The two dimensional bias correction methodology for temperature and precipitation, developed by Piani et al. (2012) for station data, was applied to the CCSM4 (NCAR) model gridded output from the CMIP5 dataset and a 40 year gridded dataset over Southeastern South America (Tencer et al., 2011; Jones et al., 2012). Copula density functions of observed temperature and precipitation showed significant structure when subsets of sixteen gridpoints were pooled together. By contrast no structure is detectable in copulas of GCM data. By construction, independent one dimensional bias correction of temperature and precipitation cannot correct copula density distributions hence, the 2D method is applied. The method is validated, as customary, by calibrating and subsequently validating the methodology with non-overlapping 20 year time periods. Visual inspection of single copula density functions for all grid points is unfeasible. Hence the bias correction method is validated by calculating a Kolmogorov-Smirnoff (KS) type statistic measuring the distance between observed and simulated and between observed and corrected copulas at each grid point. Results for the KS statistic are plotted in the figure shown. The methodology clearly shows great potential for application to climate impact modeling. References Jones, P. D., Lister, D. H., Harpham, C., Rusticucci, M. and Penalba, O. (2013), Construction of a daily precipitation grid for southeastern South America for the period 1961-2000. Int. J. Climatol., 33: 2508-2519. doi: 10.1002/joc.3605 Piani, C., &Haerter, J. O. (2012). Two dimensional bias correction of temperature and precipitation copulas in climate models. Geophysical Research Letters, 39(20). Tencer, B., Rusticucci, M., Jones, P., & Lister, D. (2011).A Southeastern South American Daily Gridded Dataset of Observed Surface Minimum and Maximum Temperature for 1961-2000. Bulletin of the American Meteorological Society, 92(10). Figure. Kolmogorov-Smirnoff type statistic

  7. Snap, crackle, pop: sub-grid supernova feedback in AMR simulations of disc galaxies

    Science.gov (United States)

    Rosdahl, Joakim; Schaye, Joop; Dubois, Yohan; Kimm, Taysun; Teyssier, Romain

    2017-04-01

    We compare five sub-grid models for supernova (SN) feedback in adaptive mesh refinement (AMR) simulations of isolated dwarf and L-star disc galaxies with 20-40 pc resolution. The models are thermal dump, stochastic thermal, 'mechanical' (injecting energy or momentum depending on the resolution), kinetic and delayed cooling feedback. We focus on the ability of each model to suppress star formation and generate outflows. Our highest resolution runs marginally resolve the adiabatic phase of the feedback events, which correspond to 40 SN explosions, and the first three models yield nearly identical results, possibly indicating that kinetic and delayed cooling feedback converge to wrong results. At lower resolution all models differ, with thermal dump feedback becoming inefficient. Thermal dump, stochastic and mechanical feedback generate multiphase outflows with mass loading factors β ≪ 1, which is much lower than observed. For the case of stochastic feedback, we compare to published SPH simulations, and find much lower outflow rates. Kinetic feedback yields fast, hot outflows with β ∼ 1, but only if the wind is in effect hydrodynamically decoupled from the disc using a large bubble radius. Delayed cooling generates cold, dense and slow winds with β > 1, but large amounts of gas occupy regions of temperature-density space with short cooling times. We conclude that either our resolution is too low to warrant physically motivated models for SN feedback, that feedback mechanisms other than SNe are important or that other aspects of galaxy evolution, such as star formation, require better treatment.

  8. Numerical simulation of flow in mechanical heart valves: grid resolution and the assumption of flow symmetry.

    Science.gov (United States)

    Ge, Liang; Jones, S Casey; Sotiropoulos, Fotis; Healy, Timothy M; Yoganathan, Ajit P

    2003-10-01

    A numerical method is developed for simulating unsteady, 3-D, laminar flow through a bileaflet mechanical heart valve with the leaflets fixed. The method employs a dual-time-stepping artificial-compressibility approach together with overset (Chimera) grids and is second-order accurate in space and time. Calculations are carried out for the full 3-D valve geometry under steady inflow conditions on meshes with a total number of nodes ranging from 4 x 10(5) to 1.6 x 10(6). The computed results show that downstream of the leaflets the flow is dominated by two pairs of counter-rotating vortices, which originate on either side of the central orifice in the aortic sinus and rotate such that the common flow of each pair is directed away from the aortic wall. These vortices intensify with Reynolds number, and at a Reynolds number of approximately 1200 their complex interaction leads to the onset of unsteady flow and the break of symmetry with respect to both geometric planes of symmetry. Our results show the highly 3-D structure of the flow; question the validity of computationally expedient assumptions of flow symmetry; and demonstrate the need for highly resolved, fully 3-D simulations if computational fluid dynamics is to accurately predict the flow in prosthetic mechanical heart valves.

  9. Grid generation and adaptation for the Direct Simulation Monte Carlo Method. [for complex flows past wedges and cones

    Science.gov (United States)

    Olynick, David P.; Hassan, H. A.; Moss, James N.

    1988-01-01

    A grid generation and adaptation procedure based on the method of transfinite interpolation is incorporated into the Direct Simulation Monte Carlo Method of Bird. In addition, time is advanced based on a local criterion. The resulting procedure is used to calculate steady flows past wedges and cones. Five chemical species are considered. In general, the modifications result in a reduced computational effort. Moreover, preliminary results suggest that the simulation method is time step dependent if requirements on cell sizes are not met.

  10. Fibonacci Grids

    Science.gov (United States)

    Swinbank, Richard; Purser, James

    2006-01-01

    Recent years have seen a resurgence of interest in a variety of non-standard computational grids for global numerical prediction. The motivation has been to reduce problems associated with the converging meridians and the polar singularities of conventional regular latitude-longitude grids. A further impetus has come from the adoption of massively parallel computers, for which it is necessary to distribute work equitably across the processors; this is more practicable for some non-standard grids. Desirable attributes of a grid for high-order spatial finite differencing are: (i) geometrical regularity; (ii) a homogeneous and approximately isotropic spatial resolution; (iii) a low proportion of the grid points where the numerical procedures require special customization (such as near coordinate singularities or grid edges). One family of grid arrangements which, to our knowledge, has never before been applied to numerical weather prediction, but which appears to offer several technical advantages, are what we shall refer to as "Fibonacci grids". They can be thought of as mathematically ideal generalizations of the patterns occurring naturally in the spiral arrangements of seeds and fruit found in sunflower heads and pineapples (to give two of the many botanical examples). These grids possess virtually uniform and highly isotropic resolution, with an equal area for each grid point. There are only two compact singular regions on a sphere that require customized numerics. We demonstrate the practicality of these grids in shallow water simulations, and discuss the prospects for efficiently using these frameworks in three-dimensional semi-implicit and semi-Lagrangian weather prediction or climate models.

  11. About Distributed Simulation-based Optimization of Forming Processes using a Grid Architecture

    Science.gov (United States)

    Grauer, Manfred; Barth, Thomas

    2004-06-01

    Permanently increasing complexity of products and their manufacturing processes combined with a shorter "time-to-market" leads to more and more use of simulation and optimization software systems for product design. Finding a "good" design of a product implies the solution of computationally expensive optimization problems based on the results of simulation. Due to the computational load caused by the solution of these problems, the requirements on the Information&Telecommunication (IT) infrastructure of an enterprise or research facility are shifting from stand-alone resources towards the integration of software and hardware resources in a distributed environment for high-performance computing. Resources can either comprise software systems, hardware systems, or communication networks. An appropriate IT-infrastructure must provide the means to integrate all these resources and enable their use even across a network to cope with requirements from geographically distributed scenarios, e.g. in computational engineering and/or collaborative engineering. Integrating expert's knowledge into the optimization process is inevitable in order to reduce the complexity caused by the number of design variables and the high dimensionality of the design space. Hence, utilization of knowledge-based systems must be supported by providing data management facilities as a basis for knowledge extraction from product data. In this paper, the focus is put on a distributed problem solving environment (PSE) capable of providing access to a variety of necessary resources and services. A distributed approach integrating simulation and optimization on a network of workstations and cluster systems is presented. For geometry generation the CAD-system CATIA is used which is coupled with the FEM-simulation system INDEED for simulation of sheet-metal forming processes and the problem solving environment OpTiX for distributed optimization.

  12. Communication Skills, Cultural Sensitivity, and Collaboration in an Experiential Language Village Simulation

    Science.gov (United States)

    Clark, Allen; Minami, Nathan

    2015-01-01

    This article discusses five college students' experiences in a simulated full-immersion, Arabic-speaking language village and the impact of that experience on learners' beliefs about the power of collaborative learning, the critical importance of cultural awareness, the efficacy of learning languages within a functioning community of practice, and…

  13. Using Concept Maps to Facilitate Collaborative Simulation-Based Inquiry Learning

    NARCIS (Netherlands)

    Gijlers, A.H.; Jong, de T.

    2013-01-01

    This study investigates the effect of a shared concept-mapping task on high school students' learning about kinematics in a collaborative simulation-based inquiry setting. Pairs of students were randomly assigned to a concept-mapping condition (12 pairs) or a control condition (13 pairs). Students i

  14. Leading Game-Simulation Development Teams: Enabling Collaboration with Faculty Experts

    Science.gov (United States)

    Aleckson, Jon D.

    2010-01-01

    This study explored how educational technology development leaders can facilitate increased collaboration between the instructional design and development team and faculty member experts when developing games and simulations. A qualitative, case study method was used to analyze interviews and documents, and Web postings related specifically to…

  15. Making It Real: Using a Collaborative Simulation to Teach Crisis Communications

    Science.gov (United States)

    Olson, K. S.

    2012-01-01

    Even seasoned public relations (PR) practitioners can find it difficult to handle communications during a crisis situation when the consequences of making poor decisions may seem overwhelming. This article shares results from using a collaborative simulation to teach college students about crisis communications in an advanced-level PR course.…

  16. Using interprofessional simulation to improve collaborative competences for nursing, physiotherapy, and respiratory therapy students.

    Science.gov (United States)

    King, Judy; Beanlands, Sarah; Fiset, Valerie; Chartrand, Louise; Clarke, Shelley; Findlay, Tarra; Morley, Michelle; Summers, Ian

    2016-09-01

    Within the care of people living with respiratory conditions, nursing, physiotherapy, and respiratory therapy healthcare professionals routinely work in interprofessional teams. To help students prepare for their future professional roles, there is a need for them to be involved in interprofessional education. The purpose of this project was to compare two different methods of patient simulation in improving interprofessional competencies for students in nursing, physiotherapy, and respiratory therapy programmes. The Canadian Interprofessional Health Collaborative competencies of communication, collaboration, conflict resolution patient/family-centred care, roles and responsibilities, and team functioning were measured. Using a quasi-experimental pre-post intervention approach two different interprofessional workshops were compared: the combination of standardised and simulated patients, and exclusively standardised patients. Students from nursing, physiotherapy, and respiratory therapy programmes worked together in these simulation-based activities to plan and implement care for a patient with a respiratory condition. Key results were that participants in both years improved in their self-reported interprofessional competencies as measured by the Interprofessional Collaborative Competencies Attainment Survey (ICCAS). Participants indicated that they found their interprofessional teams did well with communication and collaboration. But the participants felt they could have better involved the patients and their family members in the patient's care. Regardless of method of patient simulation used, mannequin or standardised patients, students found the experience beneficial and appreciated the opportunity to better understand the roles of other healthcare professionals in working together to help patients living with respiratory conditions.

  17. A Simulation-Based LED Design Project in Photonics Instruction Based on Industry-University Collaboration

    Science.gov (United States)

    Chang, S. -H.; Chen, M. -L.; Kuo, Y. -K.; Shen, Y. -C.

    2011-01-01

    In response to the growing industrial demand for light-emitting diode (LED) design professionals, based on industry-university collaboration in Taiwan, this paper develops a novel instructional approach: a simulation-based learning course with peer assessment to develop students' professional skills in LED design as required by industry as well as…

  18. Agent Behavior-Based Simulation Study on Mass Collaborative Product Development Process

    Directory of Open Access Journals (Sweden)

    Shuo Zhang

    2015-01-01

    Full Text Available Mass collaborative product development (MCPD benefits people by high innovation products with lower cost and shorter lead time due to quick development of group innovation, Internet-based customization, and prototype manufacturing. Simulation is an effective way to study the evolution process and therefore to guarantee the success of MCPD. In this paper, an agent behavior-based simulation approach of MCPD is developed, which models the MCPD process as the interactive process of design agents and the environment objects based on Complex Adaptive System (CAS theory. Next, the structure model of design agent is proposed, and the modification and collaboration behaviors are described. Third, the agent behavior-based simulation flow of MCPD is designed. At last, simulation experiments are carried out based on an engineering case of mobile phone design. The experiment results show the following: (1 the community scale has significant influence on MCPD process; (2 the simulation process can explicitly represent the modification and collaboration behaviors of design agents; (3 the community evolution process can be observed and analyzed dynamically based on simulation data.

  19. Dynamic Modeling, Control and Simulation of a Wind and PV Hybrid System for Grid Connected Application Using MATLAB

    Directory of Open Access Journals (Sweden)

    D. Mahesh Naik

    2014-07-01

    Full Text Available This paper proposes a dynamic modeling and control strategy for a grid connected hybrid wind and photovoltaic (PV energy system inter-connected to electrical grid through power electronic interface. A gearless permanent magnet synchronous generator (PMSG is used to capture the maximum wind energy. The PV and wind systems are connected dc-side of the voltage source inverter through a boost converter individually and maintain a fixed dc output at dc link. A proper control scheme is required to operate power converters to match up the grid connection requirements. This study considered the performance of modeled hybrid system under different case scenarios. All simulation models are developed using MATLAB/Simulink.

  20. Large-Eddy Simulations of turbulent flows with lattice Boltzmann dynamics and dynamical system sub-grid models

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, two sub-grid scale (SGS) models are introduced into the Lattice Boltzmann Method (LBM), i.e., the dynamics SGS model and the dynamical system SGS model, and applied to numerically solving three-dimensional high Re turbulent cavity flows. Results are compared with those obtained from the Smagorinsky model and direct numerical simulation for the same cases. It is shown that the method with LBM dynamics SGS model has advantages of fast computation speed, suitable to simulate high Re turbulent flows. In addition, it can capture detailed fine structures of turbulent flow fields. The method with LBM dynamical system SGS model dose not contain any adjustable parameters, and can be used in simulations of various complicated turbulent flows to obtain correct information of sub-grid flow field, such as the backscatter of energy transportation between large and small scales. A new average method of eliminating the inherent unphysical oscillation of LBM is also given in the paper.

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

    CERN Document Server

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

    2015-01-01

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

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

    2015-12-21

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

  4. Resolution dependence of deep convections in a global simulation from over 10-kilometer to sub-kilometer grid spacing

    Science.gov (United States)

    Kajikawa, Yoshiyuki; Miyamoto, Yoshiaki; Yoshida, Ryuji; Yamaura, Tsuyoshi; Yashiro, Hisashi; Tomita, Hirofumi

    2016-12-01

    The success of sub-kilometer global atmospheric simulation opens the door for resolving deep convections, which are fundamental elements of cloudy disturbances that drive global circulation. A previous study found that the essential change in the simulated convection properties occurred at a grid spacing of about 2 km as a global mean. In grid-refinement experiments, we conducted further comprehensive analysis of the global-mean state and the characteristics of deep convection, to clarify the difference of the essential change by location and environment. We found that the essential change in convection properties was different in the location and environment for each cloudy disturbance. The convections over the tropics show larger resolution dependence than convections over mid-latitudes, whereas no significant difference was found in convections over land or ocean. Furthermore, convections over cloudy disturbances [(i.e., Madden-Julian oscillation (MJO), tropical cyclones (TCs)] show essential change of convection properties at about 1 km grid spacing, suggesting resolution dependence. As a result, convections not categorized as cloudy disturbances make a large contribution to the global-mean convection properties. This implies that convections in disturbances are largely affected organization processes and hence have more horizontal resolution dependence. In contrast, other categorized convections that are not involved in major cloudy disturbances show the essential change at about 2 km grid spacing. This affects the latitude difference of the resolution dependence of convection properties and hence the zonal-mean outgoing longwave radiation (OLR). Despite the diversity of convection properties, most convections are resolved at less than 1 km grid spacing. In the future, longer integration of global atmosphere, to 0.87 km grid spacing, will stimulate significant discussion about the interaction between the convections and cloudy disturbances.

  5. Temperature and precipitation extremes in century-long gridded observations, reanalyses, and atmospheric model simulations

    Science.gov (United States)

    Donat, Markus G.; Alexander, Lisa V.; Herold, Nicholas; Dittus, Andrea J.

    2016-10-01

    Knowledge about long-term changes in climate extremes is vital to better understand multidecadal climate variability and long-term changes and to place today's extreme events in a historical context. While global changes in temperature and precipitation extremes since the midtwentieth century are well studied, knowledge about century-scale changes is limited. This paper analyses a range of largely independent observations-based data sets covering 1901-2010 for long-term changes and interannual variability in daily scale temperature and precipitation extremes. We compare across data sets for consistency to ascertain our confidence in century-scale changes in extremes. We find consistent warming trends in temperature extremes globally and in most land areas over the past century. For precipitation extremes we find global tendencies toward more intense rainfall throughout much of the twentieth century; however, local changes are spatially more variable. While global time series of the different data sets agree well after about 1950, they often show different changes during the first half of the twentieth century. In regions with good observational coverage, gridded observations and reanalyses agree well throughout the entire past century. Simulations with an atmospheric model suggest that ocean temperatures and sea ice may explain up to about 50% of interannual variability in the global average of temperature extremes, and about 15% in the global average of moderate precipitation extremes, but local correlations are mostly significant only in low latitudes.

  6. A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

    Energy Technology Data Exchange (ETDEWEB)

    Klassen, Mikhail; Pudritz, Ralph E. [Department of Physics and Astronomy, McMaster University 1280 Main Street W, Hamilton, ON L8S 4M1 (Canada); Kuiper, Rolf [Max Planck Institute for Astronomy Königstuhl 17, D-69117 Heidelberg (Germany); Peters, Thomas [Institut für Computergestützte Wissenschaften, Universität Zürich Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Banerjee, Robi; Buntemeyer, Lars, E-mail: klassm@mcmaster.ca [Hamburger Sternwarte, Universität Hamburg Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2014-12-10

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodyanmics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.

  7. A General Hybrid Radiation Transport Scheme for Star Formation Simulations on an Adaptive Grid

    Science.gov (United States)

    Klassen, Mikhail; Kuiper, Rolf; Pudritz, Ralph E.; Peters, Thomas; Banerjee, Robi; Buntemeyer, Lars

    2014-12-01

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodyanmics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.

  8. Direct numerical simulation of particulate flows with an overset grid method

    Science.gov (United States)

    Koblitz, A. R.; Lovett, S.; Nikiforakis, N.; Henshaw, W. D.

    2017-08-01

    We evaluate an efficient overset grid method for two-dimensional and three-dimensional particulate flows for small numbers of particles at finite Reynolds number. The rigid particles are discretised using moving overset grids overlaid on a Cartesian background grid. This allows for strongly-enforced boundary conditions and local grid refinement at particle surfaces, thereby accurately capturing the viscous boundary layer at modest computational cost. The incompressible Navier-Stokes equations are solved with a fractional-step scheme which is second-order-accurate in space and time, while the fluid-solid coupling is achieved with a partitioned approach including multiple sub-iterations to increase stability for light, rigid bodies. Through a series of benchmark studies we demonstrate the accuracy and efficiency of this approach compared to other boundary conformal and static grid methods in the literature. In particular, we find that fully resolving boundary layers at particle surfaces is crucial to obtain accurate solutions to many common test cases. With our approach we are able to compute accurate solutions using as little as one third the number of grid points as uniform grid computations in the literature. A detailed convergence study shows a 13-fold decrease in CPU time over a uniform grid test case whilst maintaining comparable solution accuracy.

  9. Numerical solution of Poisson equation on adaptive multiresolution grid. Application to streamer discharge simulations

    CERN Document Server

    Duarte, Max; Massot, Marc; Bourdon, Anne

    2013-01-01

    In this paper we investigate the numerical solution of Poisson equations on adapted structured grids generated by multiresolution analysis. Such an approach not only involves important savings in computational costs, but also allows us to conduct a mathematical description of the numerical approximations in the context of biorthogonal wavelet decomposition. In contrast to most adaptive meshing techniques in the literature that solve the corresponding system of discrete equations level-wise throughout the set of adapted grids, we introduce a new numerical procedure, mainly based on inter-level operations, to represent in a consistent way the elliptic operators discretized on the adapted grid. In this way the discrete problem can be solved at once over the entire computational domain strongly coupling inter-grid relations as a completely separate process, independent of the mesh generation or any other grid-related data structure or geometric consideration, while the multiresolution framework guarantees numeric...

  10. Use of CAPE-OPEN Standard in US-UK Collaboration on Virtual Plant Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zitney, S.E.

    2007-11-01

    Under the auspices of a US-UK Memorandum of Understanding and Implementing Agreement for fossil energy R&D (http://us-uk.fossil.energy.gov/), the US Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) and the UK Department of Trade and Industry (DTI) have recently completed a three-year collaboration on virtual plant modeling and simulation technology for advanced fossil-energy power generation systems. The R&D collaboration was aimed at taking full advantage of the synergies between NETL’s ongoing Advanced Process Engineering Co-Simulator (APECS) project and the UK’s three-year Virtual Plant Demonstration Model (VPDM) project. The key objective of this collaboration has been the development of compatible, open standards-based US and UK technology for process/equipment co-simulation. To achieve plug-and-play model interoperability, the collaboration leveraged the process-industry CAPE-OPEN (CO) software standard which is managed and disseminated by the CO Laboratories Network (www.colan.org).

  11. Prototype of GRID infrastructure for H yields gammagamma study with full QCD background simulation and reconstruction for CMS at LHC

    CERN Document Server

    Litvin, V; Shevchenko, S; Koranda, S; Loftis, B; Towns, J; Livny, M; Couvares, P; Tannenbaum, T; Frey, J

    2003-01-01

    CMS experiment at CERN Large Hadron Collider (LHC) will begin taking data in 2007. Along with the Petabytes of data expected to be collected, CMS will also generate an enormous amount of Monte Carlo simulation data. This paper describes solutions developed at Caltech to address the issue of controlled generation of large amounts of Monte Carlo simulation data using distributed Alliance resources. We will report on the results of production using Grid tools (Globus, Condor-G) to knit together resources from various institutions within Alliance in NPACI framework. The results of this effort have been used for the study of the H yields gammagamma decay channel with full background simulation.

  12. Collaborative design for embedded systems co-modelling and co-simulation

    CERN Document Server

    Fitzgerald, John; Verhoef, Marcel

    2014-01-01

    One of the most significant challenges in the development of embedded and cyber-physical systems is the gap between the disciplines of software and control engineering. In a marketplace, where rapid innovation is essential, engineers from both disciplines need to be able to explore system designs collaboratively, allocating responsibilities to software and physical elements, and analyzing trade-offs between them.To this end, this book presents a framework that allows the very different kinds of design models - discrete-event (DE) models of software and continuous time (CT) models of the physical environment - to be analyzed and simulated jointly, based on common scenarios. The individual chapters provide introductions to both sides of this co-simulation technology, and give a step-by-step guide to the methodology for designing and analyzing co-models. They are grouped into three parts: Part I introduces the technical basis for collaborative modeling and simulation with the Crescendo technology. Part II contin...

  13. Simulating the Upper Ocean Circulation on the Belize Shelf: An Application of a Triply Nested-Grid Ocean Circulation Model

    Institute of Scientific and Technical Information of China (English)

    SHENG Jinyu; TANG Liqun; WANG Liang

    2005-01-01

    We present a three-level nested-grid ocean circulation modeling system for the Belize shelf of the western Caribbean Sea. The nested-grid system has three subcomponents: a coarse-resolution outer model of the western Caribbean Sea; an intermediate-resolution middle model of the southern Meso-American Barrier Reef System; and a fine-resolution inner model of the Belize shelf. The two-way nesting technique based on the semi-prognostic method is used to exchange information between the three subcomponents. We discuss two applications of the nested-grid system in this study. In the first application we simulate the seasonal mean circulation in the region, with the nested system forced by monthly mean surface fluxes and boundary forcing. The model results reproduce the general circulation features on the western Caribbean Sea and meso-scale circulation features on the Belize shelf. In the second application, we simulate the storm-induced circulation during Hurricane Mitch in 1998, with the nested-grid system forced by the combination of monthly mean forcing and idealized wind stress associated with the storm. The model results demonstrate that the storm-induced currents transport a large amount of estuarinc waters from coastal regions of Honduras and Guatemala to offshore reef atolls.

  14. OVERLAPPING GRIDS FOR THE SIMULATION OF PARTICLE INTERACTION AT THE MICRO SCALE

    Institute of Scientific and Technical Information of China (English)

    Hermann; Nirschl

    2005-01-01

    This paper describes the use of overlapping grids for the calculation of flow around single and multipleparticle configurations at the micro scale. The basic equations for calculation are those for conservation of mass and momentum which are solved using a common Finite-Volume formulation. The hydrodynamic particle-particle and particle-wall interaction can be calculated by using an overlapping or Chimera grid scheme. With the grid structuring procedure it is possible to use simple and structured grids around the particles and the overall main grid geometry. The particle grids are lapped over the main grid such that they can move independently after each time step without remeshing the whole geometry. The paper gives results for the validation of the code developed for general test cases, for a rotating ellipsoid in simple shear flow, the flow around particles attached to a wall, the motion of a particle in the vicinity of a wall and some results for the flow through a packed bed configuration.

  15. International collaborative research on infectious diseases by Japanese universities and institutes in Asia and Africa, with a special emphasis on J-GRID.

    Science.gov (United States)

    Shinoda, Sumio; Imamura, Daisuke; Mizuno, Tamaki; Miyoshi, Shin-Ichi; Ramamurthy, Thandavrayan

    2015-01-01

    In developed countries including Japan, malignant tumor (cancer), heart disease and cerebral apoplexy are major causes of death, but infectious diseases are still responsible for a high number of deaths in developing countries, especially among children aged less than 5 years. World Health Statistics published by WHO reports a high percentage of mortality from infectious diseases in children, and many of these diseases may be subject to transmission across borders and could possibly invade Japan.  Given this situation, the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan initiated Phase I of the Program of Founding Research Centers for Emerging and Reemerging Infectious Disease, which ran from FY 2005 to 2009, and involved 8 Japanese universities and 2 research centers. The program was established for the following purposes: 1) creation of a domestic research structure to promote the accumulation of fundamental knowledge about infectious diseases, 2) establishment of 13 overseas research collaboration centers in 8 countries at high risk of emerging and reemerging infections and at which Japanese researchers are stationed and conduct research in partnership with overseas instructors, 3) development of a network among domestic and overseas research centers, and 4) development of human resources.  The program was controlled under MEXT and managed by the RIKEN Center of Research Network for Infectious Diseases (Riken CRNID). Phase II of the program was set up as the Japan Initiative for Global Research Network on Infectious Diseases (J-GRID), and has been running in FY 2010-2014.  Phase III will start in April 2015, and will be organized by the newly established Japanese governmental organization "Japan Agency for Medical Research and Development (AMED)", the so-called Japanese style NIH.  The Collaborative Research Center of Okayama University for Infectious Diseases in India (CRCOUI) was started up in 2007 at the National

  16. Simulation of tandem hydrofoils by finite volume method with moving grid system; Henkei koshi wo tsukatta yugen taisekiho ni yoru tandem suichuyoku no simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kawashima, H. [Ship Research Inst., Tokyo (Japan); Miyata, H. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering

    1996-12-31

    With an objective to clarify possibility of application of time-advancing calculated fluid dynamic (CFD) simulation by using a finite volume method with moving grid system, a simulation was performed on motion of a ship with hydrofoils including the control system therein. The simulation consists of a method that couples a moving grid system technology, an equation of motion, and the control system. Complex interactions between wings and with free surface may be considered automatically by directly deriving fluid force from a flow field by using the CFD. In addition, two-dimensional flows around tandem hydrofoils were calculated to solve the motion problem within a vertical plane. As a result, the following results were obtained: a finite volume method using a dynamic moving grid system method was applied to problems in non-steady tandem hydrofoils to show its usefulness; a method that couples the CFD with the equation of motion was applied to the control problems in the tandem hydrofoils to show possibility of a new technology for simulating motions; and a simulation that considers such wing interference as wave creation, discharged vortices, and associated flows was shown useful to understand characteristics of the tandem hydrofoils. 13 refs., 14 figs.

  17. Exponentially Expanded Grid Network Approach (EEGNA): An Efficient Way for the Simulation of Electrochemical Problems at Spherical, Cylindrical and Rotating-disk Electrodes

    Institute of Scientific and Technical Information of China (English)

    邓兆祥; 林祥钦; 童中华

    2005-01-01

    An exponentially expanded space grid technique has been employed in the network simulation of chronoamperometric and voltammetric problems in spherical, cylindrical and rotating-disk electrode systems, leading to an effective simulation strategy for electrochemical problems: exponentially expanded grid network approach (EEGNA). The success of this method is largely due to the improved ability in processing the boundary singularities existing for non-planar diffusions and the enhanced simulation speed and accuracy in contrast to the uniform or quasi-uniform grid network approach.

  18. Multi-grid Beam and Warming scheme for the simulation of unsteady ...

    African Journals Online (AJOL)

    2010-03-08

    Mar 8, 2010 ... cal methods, the implicit finite-difference method and finite element method ... a few iterations, but after that these methods will be converged slowly. Multi-grid ...... VENUTELLI M (2002) Stability and accuracy of weighted four-.

  19. 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.

  20. Partnering to provide simulated learning to address Interprofessional Education Collaborative core competencies.

    Science.gov (United States)

    Murphy, Judy I; Nimmagadda, Jayashree

    2015-05-01

    Learning to effectively communicate and work with other professionals requires skill, yet interprofessional education is often not included in the undergraduate healthcare provider curriculum. Simulation is an effective pedagogy to bring students from multiple professions together for learning. This article describes a pilot study where nursing and social work students learned together in a simulated learning activity, which was evaluated to by the Readiness for Interprofessional Learning Scale (RIPLS). The RIPLS was used before and after the simulated activity to determine if this form of education impacted students' perceptions of readiness to learn together. Students from both professions improved in their RIPLS scores. Students were also asked to identify their interprofessional strengths and challenges before and after the simulation. Changes were identified in qualitative data where reports of strengths and challenges indicated learning and growth had occurred. In conclusion, this pilot study suggests that interprofessional simulation can be an effective method to integrate Interprofessional Education Collaborative core competencies into the curriculum.

  1. Influence of model grid size on the simulation of PM2.5 and the related excess mortality in Japan

    Science.gov (United States)

    Goto, D.; Ueda, K.; Ng, C. F.; Takami, A.; Ariga, T.; Matsuhashi, K.; Nakajima, T.

    2016-12-01

    Aerosols, especially PM2.5, can affect air pollution, climate change, and human health. The estimation of health impacts due to PM2.5 is often performed using global and regional aerosol transport models with various horizontal resolutions. To investigate the dependence of the simulated PM2.5 on model grid sizes, we executed two simulations using a high-resolution model ( 10km; HRM) and a low-resolution model ( 100km; LRM, which is a typical value for general circulation models). In this study, we used a global-to-regional atmospheric transport model to simulate PM2.5 in Japan with a stretched grid system in HRM and a uniform grid system in LRM for the present (the 2000) and the future (the 2030, as proposed by the Representative Concentrations Pathway 4.5, RCP4.5). These calculations were performed by nudging meteorological fields obtained from an atmosphere-ocean coupled model and providing emission inventories used in the coupled model. After correcting for bias, we calculated the excess mortality due to long-term exposure to PM2.5 for the elderly. Results showed the LRM underestimated by approximately 30 % (of PM2.5 concentrations in the 2000 and 2030), approximately 60 % (excess mortality in the 2000) and approximately 90 % (excess mortality in 2030) compared to the HRM results. The estimation of excess mortality therefore performed better with high-resolution grid sizes. In addition, we also found that our nesting method could be a useful tool to obtain better estimation results.

  2. Smart Grid Special; Smart Grid Special

    Energy Technology Data Exchange (ETDEWEB)

    Mokoginta, L. [Energiecooperatie ' Wij Krijgen Kippen' , Amsterdam (Netherlands); Messing, M. [Stichting Energietransitie Nederland, Boxtel (Netherlands); Slootweg, H. [Technische Universiteit Eindhoven TUE, Eindhoven (Netherlands); Van der Steen, L.; Brugman, L. [SquareWise, Amsterdam (Netherlands); Bles, M.; Blom, M. [CE Delft, Delft (Netherlands); Nachtegaal, H.; Hoekstra, R. [Bijl partners in public relations, Rotterdam (Netherlands); Van Zutphen, M. [CapGemini, Utrecht (Netherlands); Bakker, D. [PNO Consultants, Schiphol (Netherlands); Van Leeuwen, M. [Norton Rose, Amsterdam (Netherlands); Van Vlerken, J.; De Leeuw, M.; Wijnants, H.J.; Holwerda, B.; Bosch, N.

    2012-06-15

    A series of 17 articles is dedicated to various aspects of smart grids: expert opinions, the key role of smart grids in a sustainable energy transition, the role of the energy consumer and the grid operators, an energy transition project in the South of Amsterdam (Netherlands), the need for collaboration (e.g. through the Smart Energy Collective), the establishment of local energy corporations, the question whether smart grids are a hype or a necessity, costs and benefits of smart grids, deployment of intelligent smart grids in business areas (experimental areas), the opportunity of deploying Direct Current (DC) grids for an improved energy balance, the Smart Power City Apeldoorn project (SPCA), the experimental area of CloudPower on the isle of Texel, innovation contracts for smart grids, the increase of local, small-scale electricity production, and smart grid pilot projects on Europe. [Dutch] In 17 artikelen wordt aandacht besteed aan diverse aspecten van 'smart grids': meningen van experts, de sleutelrol van smart grids in een duurzame energietransitie, de rol van de energieconsument en de netbeheerders, een energietransitie-project in Amsterdam-Zuid, de noodzaak tot samenwerking (onder meer d.m.v. het Smart Energy Collective), de oprichting van lokale energiecooperaties, de vraag of smart grids een hype zijn of noodzaak, kosten en baten van smart grids, de toepassing van intelligente energienetwerken op bedrijventerreinen ('proeftuinen'), de mogelijkheid om gelijkspanningsnetten toe te passen voor een betere energiebalans, het project Smart Power City Apeldoorn (SPCA), de proeftuin CloudPower op Texel, innovatiecontracten m.b.t. smart grids, de toename van lokale, kleinschalige elektriciteitsproductie, smart grid demonstratieprojecten in Europa.

  3. Cooperative International Simulations with McStas

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Vickie E [ORNL; Chen, Meili [ORNL; Cobb, John W [ORNL; Farhi, Emmanuel N [ORNL; Hagen, Mark E [ORNL; Kohl, James Arthur [ORNL; Lefmann, Kim [ORNL; Lin, Jiao [ORNL; Miller, Stephen D [ORNL; Reuter, Michael A [ORNL; Vazhkudai, Sudharshan S [ORNL; Willendrup, Peter K [ORNL

    2007-01-01

    McStas is a neutron ray-trace simulation package that simulates neutron scattering instruments. Its developers at Riso National Laboratory in Denmark and the Institute Max von Laue-Paul Langevin in France are collaborating with the SNS instrument scientists, the Neutron Science TeraGrid developers, and the DANSE developers to improve the package and make it available to more researchers. Distributed computing on the TeraGrid, the UK eScience Grid, the Open Science Grid, etc. is a goal of this collaboration as well as improved visualization, standardized NeXus output, improved performance, more sample kernels, event mode and histogram interfaces, and an analysis interface.

  4. A web-based, collaborative modeling, simulation, and parallel computing environment for electromechanical systems

    Directory of Open Access Journals (Sweden)

    Xiaoliang Yin

    2015-03-01

    Full Text Available Complex electromechanical system is usually composed of multiple components from different domains, including mechanical, electronic, hydraulic, control, and so on. Modeling and simulation for electromechanical system on a unified platform is one of the research hotspots in system engineering at present. It is also the development trend of the design for complex electromechanical system. The unified modeling techniques and tools based on Modelica language provide a satisfactory solution. To meet with the requirements of collaborative modeling, simulation, and parallel computing for complex electromechanical systems based on Modelica, a general web-based modeling and simulation prototype environment, namely, WebMWorks, is designed and implemented. Based on the rich Internet application technologies, an interactive graphic user interface for modeling and post-processing on web browser was implemented; with the collaborative design module, the environment supports top-down, concurrent modeling and team cooperation; additionally, service-oriented architecture–based architecture was applied to supply compiling and solving services which run on cloud-like servers, so the environment can manage and dispatch large-scale simulation tasks in parallel on multiple computing servers simultaneously. An engineering application about pure electric vehicle is tested on WebMWorks. The results of simulation and parametric experiment demonstrate that the tested web-based environment can effectively shorten the design cycle of the complex electromechanical system.

  5. Contextualization and validation of the interprofessional collaborator assessment rubric (ICAR) through simulation: Pilot investigation.

    Science.gov (United States)

    Keshmiri, Fatemeh; Ponzer, Sari; Sohrabpour, AmirAli; Farahmand, Shervin; Shahi, Farhad; Bagheri-Hariri, Shahram; Soltani-Arabshahi, Kamran; Shirazi, Mandana; Masiello, Italo

    2016-01-01

    Simulation can be used for educating, evaluating and assessing psychometric properties of an instrument. The aim of this study was to contextualize and assess the validity and reliability of the Interprofessional Collaborative Assessment tool (ICAR) in an Iranian context using simulation. In this descriptive study, contextualization of the ICAR was assessed through several steps. Firstly, validity assessment was approved through expert panels and Delphi rounds. Secondly, reliability assessment was done by arranging a simulation video and assessing reproducibility, test-retest (ICC), internal consistency (Cronbach's Alpha) and inter-rater reliability (Kappa).The participants included 26 experts, 27 students and 6 staff of the Standardized Simulation Office of Teheran University of Medical Sciences. Contextualization and validity of the ICAR were approved in an Iranian context. The reliability of the tool was computed to be 0.71 according to Cronbach´s Alpha. The test-retest was calculated to be 0.76. The Iranian ICAR can be a useful tool for evaluating interprofessional collaborative competencies. The development of the instrument through a simulation scenario has been a positive prospect for researchers.

  6. NREL and SDG&E Collaboration to Support SDG&E Grid and Storage Efforts: Cooperative Research and Development Final Report, CRADA Number CRD-14-562

    Energy Technology Data Exchange (ETDEWEB)

    Baggu, Murali [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-01-01

    This project will enable effective utilization of high penetration of photovoltaics (PV) in islanded microgrids, increasing overall system efficiency, decreased fuel costs and resiliency of the overall system to help meet the SunShot goals of enhancing system integration methods to increase penetration of PV. National Renewable Energy Laboratory (NREL) will collaborate with San Diego Gas & Electric (SDG&E) to provide research and testing support to address their needs in energy storage sizing and placement, Integrated Test Facility (ITF) development, Real Time Digital Simulator (RTDS) Modeling and simulation support at ITF, Visualization and Virtual connection to Energy Systems Integration Facility (ESIF), and microgrid simulation and testing areas. Specifically in this project a real microgrid scenario with high penetration of PV (existing in SDG&E territory) is tested in the ESIF laboratory. Multiple control cases for firming PV using storage in a microgrid scenario will be investigated and tested in the laboratory setup.

  7. Issues regarding the modelling and simulation of hybrid micro grid systems

    Science.gov (United States)

    Szeidert, I.; Filip, I.; Prostean, O.

    2016-02-01

    The main followed objectives within control strategies dedicated to hybrid micro grid systems (wind/hydro/solar), that operate based on maximum power point tracking (MPPT) techniques are to improve the conversion systems efficiency and to maintain the quality of the produced electrical energy (the voltage and power factor control). One of the main goals of maximum power point tracking strategy is to achieve the harvesting of the maximal possible energy within a pre-set time period. In order to implement the control strategies for micro grid systems that operate at time variable parameter, there are usually required specific transducers (anemometer for wind speed measurement, optical rotational transducers, taco generators, etc.). In the technical literature there are presented several variants of the MPPT techniques, which are particularized at several applications (wind energy conversion systems, solar systems, hydro plants and micro grid hybrid systems). The maximum power point tracking implementations are mainly based on two-level architecture. The inferior level controls the primary variables, while the superior level represents the MPPT control structure. In the paper, authors present some micro grid structures proposed at Politehnica University Timisoara within the frame of a research grant. The paper is focused on the application of MPPT strategies on hybrid micro grid systems. There are presented several structures and control strategies and are highlighted their advantages and disadvantages, together with practical implementation guidelines.

  8. A new grid-associated algorithm in the distributed hydrological model simulations

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper presents a new grid-associated algorithm to improve the performance of a D8 algorithm based distributed hydrological model computation.The algorithm is based on the well known single-flow D8 algorithm of grid flow.This algorithm allocates calculation priorities according to the distance between the units and the outlet,then carries out the ergodic computations of the hydrological units according to the priority division.For the parallelized algorithm,a standard thread-level shared memory system for parallel programming(OpenMP-Open specifications for Multi Processing) was introduced,and the parallel coding was implemented in C lan-guage.A case study showed that the absolute speed-up ratio of the grid-associated algorithm is 1.64 over the original D8 algorithm,and the linear speed-up ratio of the parallel associated algorithm is 2.42 under 4 cores.The parallel grid-associated algorithm can be applied to a variety of research fields that use the grid method.

  9. The modeling and simulation of thermal based modified solid oxide fuel cell (SOFC for grid-connected systems

    Directory of Open Access Journals (Sweden)

    Ayetül Gelen

    2015-05-01

    Full Text Available This paper presents a thermal based modified dynamic model of a Solid Oxide Fuel Cell (SOFC for grid-connected systems. The proposed fuel cell model involves ohmic, activation and concentration voltage losses, thermal dynamics, methanol reformer, fuel utilization factor and power limiting module. A power conditioning unit (PCU, which consists of a DC-DC boost converter and a DC-AC voltage-source inverter (VSI, their controller, transformer and filter, is designed for grid-connected systems. The voltage-source inverter with six Insulated Gate Bipolar Transistor (IGBT switches inverts the DC voltage that comes from the converter into a sinusoidal voltage synchronized with the grid. The simulations and modeling of the system are developed on Matlab/Simulink environment. The performance of SOFC with converter is examined under step and random load conditions. The simulation results show that the designed boost converter for the proposed thermal based modified SOFC model has fairly followed different DC load variations. Finally, the AC bus of 400 Volt and 50 Hz is connected to a single-machine infinite bus (SMIB through a transmission line. The real and reactive power managements of the inverter are analyzed by an infinite bus system. Thus, the desired nominal values are properly obtained by means of the inverter controller.

  10. Filtered sub-grid constitutive models for fluidized gas-particle flows constructed from 3-D simulations

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Avik; Milioli, Fernando E.; Ozarkar, Shailesh; Li, Tingwen; Sun, Xin; Sundaresan, Sankaran

    2016-10-01

    The accuracy of fluidized-bed CFD predictions using the two-fluid model can be improved significantly, even when using coarse grids, by replacing the microscopic kinetic-theory-based closures with coarse-grained constitutive models. These coarse-grained constitutive relationships, called filtered models, account for the unresolved gas-particle structures (clusters and bubbles) via sub-grid corrections. Following the previous 2-D approaches of Igci et al. [AIChE J., 54(6), 1431-1448, 2008] and Milioli et al. [AIChE J., 59(9), 3265-3275, 2013], new filtered models are constructed from highly-resolved 3-D simulations of gas-particle flows. Although qualitatively similar to the older 2-D models, the new 3-D relationships exhibit noticeable quantitative and functional differences. In particular, the filtered stresses are strongly dependent on the gas-particle slip velocity. Closures for the filtered inter-phase drag, gas- and solids-phase pressures and viscosities are reported. A new model for solids stress anisotropy is also presented. These new filtered 3-D constitutive relationships are better suited to practical coarse-grid 3-D simulations of large, commercial-scale devices.

  11. CFD simulation of turbulent flow in a rod bundle with spacer grids (MATIS-H) using STAR-CCM+

    Energy Technology Data Exchange (ETDEWEB)

    Cinosi, N., E-mail: n.cinosi@imperial.ac.uk; Walker, S.P.; Bluck, M.J.; Issa, R.

    2014-11-15

    Highlights: • CDF simulation of turbulent flow generated by a typical PWR spacer grid. • Benchmarking against the MATIS-H experiments run at KAERI in Daejeon, Korea. • Deployment of various steady RANS models to compute the turbulence. • Sensitivity analysis of hardware components. - Abstract: This paper presents the CFD simulation of the turbulent flow generated by a model PWR spacer grid within a rod bundle. The investigation was part of the MATIS-H benchmark exercise, organized by the OECD-NEA, with measurements performed at the KAERI facilities in Daejeon, Korea. The study employed the CD-Adapco code Star-CCM+. An initial sensitivity study was conducted to attempt to assess the importance to the overall flow of components such as the outlet plenum and the end support grid; these were shown to be able to be safely neglected, but the tapered end portion of the rods was found to be significant, and this was incorporated in the model analyzed. A RANS model using any of K-epsilon, K-omega and Reynolds-stress turbulence models was found to be adequate for the prediction of mean velocity profiles, but they all three underestimate the time-averaged turbulent velocity components. Vorticity seems to be better predicted, although the measured values of vorticity are only presented via colored contour plots, making quantitative comparison rather difficult. Circulation, calculated via an integral for each channel, seems to be well predicted by all three models.

  12. Search for β2 adrenergic receptor ligands by virtual screening via grid computing and investigation of binding modes by docking and molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Qifeng Bai

    Full Text Available We designed a program called MolGridCal that can be used to screen small molecule database in grid computing on basis of JPPF grid environment. Based on MolGridCal program, we proposed an integrated strategy for virtual screening and binding mode investigation by combining molecular docking, molecular dynamics (MD simulations and free energy calculations. To test the effectiveness of MolGridCal, we screened potential ligands for β2 adrenergic receptor (β2AR from a database containing 50,000 small molecules. MolGridCal can not only send tasks to the grid server automatically, but also can distribute tasks using the screensaver function. As for the results of virtual screening, the known agonist BI-167107 of β2AR is ranked among the top 2% of the screened candidates, indicating MolGridCal program can give reasonable results. To further study the binding mode and refine the results of MolGridCal, more accurate docking and scoring methods are used to estimate the binding affinity for the top three molecules (agonist BI-167107, neutral antagonist alprenolol and inverse agonist ICI 118,551. The results indicate agonist BI-167107 has the best binding affinity. MD simulation and free energy calculation are employed to investigate the dynamic interaction mechanism between the ligands and β2AR. The results show that the agonist BI-167107 also has the lowest binding free energy. This study can provide a new way to perform virtual screening effectively through integrating molecular docking based on grid computing, MD simulations and free energy calculations. The source codes of MolGridCal are freely available at http://molgridcal.codeplex.com.

  13. Grid-based water quality simulation at catchment scale: Nitrogen model development and evaluation

    Science.gov (United States)

    Yang, Xiaoqiang; Jomaa, Seifeddine; Rode, Michael

    2017-04-01

    Stream water quality has been changed significantly during last few decades due to changes in human impacts. Accurate and flexible water quality models, which can properly reflect the heterogeneity and long term temporal dynamic of catchment functioning, are still needed. To this end, a new grid-based catchment water quality model was developed based on the mesoscale Hydrological Model (mHM) and the HYdrological Prediction of Environment (HYPE) model. The model structure and parameterization scheme were flexibly designed depending on the spatial heterogeneity of study sites and their specific requirements. Based on that, more detailed spatial information can be provided. Moreover, three main improvements on Nitrate sub-model were implemented: i) nitrate transport processes were conducted in physically connected river networks, allowing time-series point-source inputs added in the exact location of sewage treatment plants; ii) additional retention storage of deep groundwater was included for long term nitrate-N simulation; iii) special design for better taking into account crop rotation was implemented. Those new features can extend the model capability and facilitate the understanding of catchment mechanisms and analysis of future scenarios and measures. The newly developed model was fully verified in the Selke catchment (456 km2), central Germany. Long term discharge and water quality data have been collected at three nested gauging stations (1997-2015). The station Meisdorf, above where 72% of area is occupied by forest, represents the discharge and nutrient exports from forest area. Agricultural land dominates the lower part of the catchment (almost 96% of in-between area of the Meisdorf and the outlet station Hausneindorf) with considerable urban areas. Due to the relatively large number of model parameters, sensitivity analysis was firstly conducted. Subsequently, sensitive parameters were calibrated using stepwise and multi-variable approaches, respectively

  14. 基于实时栅格法的多机器人协作建图%Multi-robot Collaboration Mapping Based on Real-Time Grid Method

    Institute of Scientific and Technical Information of China (English)

    王曙光; 唐浩漾

    2014-01-01

    针对多机器人协作建立空间地图的问题,提出一种实时栅格法,通过控制机器人的编队,在探索环境的过程中,实时生成栅格地图,并标示出障碍的位置。机器人之间采用定向红外测距和无线通信技术保持多机器人的编队形态,同时划分栅格区域。用领导-跟随法和VHF+避障法控制编队绕过障碍。论证了该方法的基本原理及可行性,在InnoSTAR机器人平台上验证了该方法的有效性。该方法计算简单,占用存储空间小,可以使用简单廉价的传感器在小型机器人上实现,但必须要精确控制机器人编队的相对位置。%Aiming at the problem of multi-robot collaboration mapping,a real-time grid method was proposed. Grid map was cre-ated during exploration through controlling robot formations,and the obstacle was located. Using wireless communication and direction-al infrared ranging technology,the fleet formation was maintained,grid area was divided at the same time. Adapting leader-following method and VHF+ obstacle avoidance method,the formation was controlled to round obstacle. The principle and feasibility of the method were demonstrated. The effectiveness of the method was verified with InnoSTAR robot. This method has simple calculation,and it occupies less storage space,can be realized on small robot with simple sensors,but the relative position of the robot fleet must be controlled.

  15. Using gridded multimedia model to simulate spatial fate of Benzo[α]pyrene on regional scale.

    Science.gov (United States)

    Liu, Shijie; Lu, Yonglong; Wang, Tieyu; Xie, Shuangwei; Jones, Kevin C; Sweetman, Andrew J

    2014-02-01

    Predicting the environmental multimedia fate is an essential step in the process of assessing the human exposure and health impacts of chemicals released into the environment. Multimedia fate models have been widely applied to calculate the fate and distribution of chemicals in the environment, which can serve as input to a human exposure model. In this study, a grid based multimedia fugacity model at regional scale was developed together with a case study modeling the fate and transfer of Benzo[α]pyrene (BaP) in Bohai coastal region, China. Based on the estimated emission and in-site survey in 2008, the BaP concentrations in air, vegetation, soil, fresh water, fresh water sediment and coastal water as well as the transfer fluxes were derived under the steady-state assumption. The model results were validated through comparison between the measured and modeled concentrations of BaP. The model results indicated that the predicted concentrations of BaP in air, fresh water, soil and sediment generally agreed with field observations. Model predictions suggest that soil was the dominant sink of BaP in terrestrial systems. Flow from air to soil, vegetation and costal water were three major pathways of BaP inter-media transport processes. Most of the BaP entering the sea was transferred by air flow, which was also the crucial driving force in the spatial distribution processes of BaP. The Yellow River, Liaohe River and Daliao River played an important role in the spatial transformation processes of BaP. Compared with advection outflow, degradation was more important in removal processes of BaP. Sensitivities of the model estimates to input parameters were tested. The result showed that emission rates, compartment dimensions, transport velocity and degradation rates of BaP were the most influential parameters for the model output. Monte Carlo simulation was carried out to determine parameter uncertainty, from which the coefficients of variation for the estimated Ba

  16. Simulation Research on an Electric Vehicle Chassis System Based on a Collaborative Control System

    Directory of Open Access Journals (Sweden)

    Nenglian Feng

    2013-01-01

    Full Text Available This paper presents a collaborative control system for an electric vehicle chassis based on a centralized and hierarchical control architecture. The centralized controller was designed for the suspension and steering system, which is used for improving ride comfort and handling stability; the hierarchical controller was designed for the braking system, which is used for distributing the proportion of hydraulic braking and regenerative braking to improve braking performance. These two sub-controllers function at the same level of the vehicle chassis control system. In order to reduce the potential conflict between the two sub-controllers and realize a coordination optimization of electric vehicle performance, a collaborative controller was built, which serves as the upper controller to carry out an overall coordination analysis according to vehicle signals and revises the decisions of sub-controllers. A simulation experiment was carried out with the MATLAB/Simulink software. The simulation results show that the proposed collaborative control system can achieve an optimized vehicle handling stability and braking safety.

  17. Agent-Based Smart Grid Market Simulation with Connection to Real Infrastructures

    DEFF Research Database (Denmark)

    Santos, Gabriel; Pinto, Tiago; Gomes, Luis

    2015-01-01

    The consensus behind Smart Grids (SG) as one of the most promising solutions for the massive integration of renewable energy sources in power systems has led to the practical implementation of several prototypes and pilots that aim at testing and validating SG methodologies. The urgent need...

  18. Architecture of Collaborating Frameworks:Simulation,Visualisation,User Interface and Analysis

    Institute of Scientific and Technical Information of China (English)

    A.Pfeiffer; R.Giannitrapani; 等

    2001-01-01

    In modern high energy and astrophysics experiments the variety of user requirements and the complexity of the problem domain often involve the collaboration of several software frameworks,and different components are responsible for providing the functionalities related to each domain.For instance,a common use case consists in studying the physics effects and the detector performance,resulting from primary events,in a given detector configuration,to evaluate the physics reach of the experiment or optimise the detector design,Such a study typically involves various components:simulation,Visualisation,Analysis and (interactive)User Interface.We focus on the design aspects of the collaboration of these frameworks and on the technologies that help to simplify the complex process of software design.

  19. CMS Software Distribution on the LCG and OSG Grids

    CERN Document Server

    Rabbertz, K; Ashby, S; Corvo, M; Argiro, S; Darmenov, N; Darwish, R; Evans, D; Holzman, Burt; Ratnikova, N; Muzaffar, S; Nowack, A; Wildish, T; Kim, B; Weng, J; Buge, V

    2006-01-01

    The efficient exploitation of worldwide distributed storage and computing resources available in the grids require a robust, transparent and fast deployment of experiment specific software. The approach followed by the CMS experiment at CERN in order to enable Monte-Carlo simulations, data analysis and software development in an international collaboration is presented. The current status and future improvement plans are described.

  20. Computational Engineering on the Grid: Crafting a Distributed Virtual Reactor

    NARCIS (Netherlands)

    Krzhizhanovskaya, V.V.; Korkhov, V.; Ramos, T.A.; Groen, D.J.; Shoshmina, I.V.; Valuev, I.A.; Morozov, I.V.; Malyshkin, N.V.; Gorbachev, Y.E.; Sloot, P.M.A.; Sloot, P.M.A; van Albada, G.D.; Bubak, M.T.; Trefethen, A.

    2006-01-01

    This paper reports on our research into supporting collaborative distributed applications on the Grid. Our case study application, a Virtual Reactor problem solving environment, was built for simulation of industrially important technology of plasma chemical deposition. It incorporates a number of c

  1. 地区电网交流送出断面调控研究%Application Research of Collaborative Stability Analysis Technology for Multi-level Power Grid in Yunnan Power Grid

    Institute of Scientific and Technical Information of China (English)

    黄宋波; 朱余启; 杨浚文; 陈聪

    2014-01-01

    This paper focuses on the operation mode of Yunnan Power Grid after the 6 generators of Xiluodu Right-bank Power Plant being put into operation,and studies the control requirements of the AC sections of Northeast Yunnan Power Grid before and after the Xiluodu HVDC single pole being put into operation� Furthermore,this paper analyzes the power capacity distribution and com-pares the different regulating rates of power flow led by different power plants in Northeast Yunnan Power Grid� The simulation re-sults demonstrates that the regulation led by Xiluodu Right-bank Power Plant is effectively and timely capable of adjusting the power flow of the AC sending sections according to the load fluctuation and reduces the operation risk.%以2013年底溪洛渡右岸电厂6台机组投运后,溪洛渡直流单回双极投运前电网运行方式作为研究对象,研究了溪洛渡直流单极投运前后滇东北部电网交流送出断面控制要求,从多角度分析了滇东北部电网电源装机容量分布,对比了不同电厂主导滇东北部交流送出断面潮流时的调控速率,结果表明,由溪洛渡右岸电厂进行主导调控可根据负荷波动有效、及时调整滇东北部交流送出断面潮流,降低电网运行风险。

  2. Grid Interaction Technical Team Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-06-01

    The mission of the Grid Interaction Technical Team (GITT) is to support a transition scenario to large scale grid-connected vehicle charging with transformational technology, proof of concept and information dissemination. The GITT facilitates technical coordination and collaboration between vehicle-grid connectivity and communication activities among U.S. DRIVE government and industry partners.

  3. Comparison of Measured Transient Overvoltages in the Collection Grid of Nysted Offshore Wind Farm with EMT Simulations

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Holbøll, Joachim; Sørensen, T.

    2009-01-01

    This paper presents a comparison between GPS synchronized measurements of two switching operations in Nysted Offshore Wind Farm (NOWF) in Denmark, and results from electromagnetic transient (emt) simulations of these switching events using Power Factory/DIgSILENT and PSCAD/EMTDC. The collection...... grid of Nysted created in Power Factory and PSCAD was based on the information available from the wind farm as-built documentation. The cable model used in both programs was created based on the geometry and material properties of the cable. Circuit breakers and transformers were modelled by means...... of the comparable simple standard models in both tools. The results from the simulations in Power Factory and PSCAD match the measured steep fronted first wave, when one radial is energized in the wind farm. However, differences were found in both simulation tools results compared with the measurements, in the more...

  4. Two-fluid sub-grid-scale viscosity in nonlinear simulation of ballooning modes in a heliotron device

    Science.gov (United States)

    Miura, H.; Hamba, F.; Ito, A.

    2017-07-01

    A large eddy simulation (LES) approach is introduced to enable the study of the nonlinear growth of ballooning modes in a heliotron-type device, by solving fully 3D two-fluid magnetohydrodynamic (MHD) equations numerically over a wide range of parameter space, keeping computational costs as low as possible. A model to substitute the influence of scales smaller than the grid size, at sub-grid scale (SGS), and at the scales larger than it—grid scale (GS)—has been developed for LES. The LESs of two-fluid MHD equations with SGS models have successfully reproduced the growth of the ballooning modes in the GS and nonlinear saturation. The numerical results show the importance of SGS effects on the GS components, or the effects of turbulent fluctuation at small scales in low-wavenumber unstable modes, over the course of the nonlinear saturation process. The results also show the usefulness of the LES approach in studying instability in a heliotron device. It is shown through a parameter survey over many SGS model coefficients that turbulent small-scale components in experiments can contribute to keeping the plasma core pressure from totally collapsing.

  5. Atmospheric Properties from the 2006 Niamey Deployment and Climate Simulation with a Geodesic Grid Coupled Climate Model Third Quarter 2008

    Energy Technology Data Exchange (ETDEWEB)

    JH Mather; DA Randall; CJ Flynn

    2008-06-30

    In 2008, the Atmospheric Radiation Measurement (ARM) Program and the Climate Change Prediction Program (CCPP) have been asked to produce joint science metrics. For CCPP, the metrics will deal with a decade-long control simulation using geodesic grid-coupled climate model. For ARM, the metrics will deal with observations associated with the 2006 deployment of the ARM Mobile Facility (AMF) to Niamey, Niger. Specifically, ARM has been asked to deliver data products for Niamey that describe cloud, aerosol, and dust properties. This report describes the aerosol optical depth (AOD) product.

  6. A dual communicator and dual grid-resolution algorithm for petascale simulations of turbulent mixing at high Schmidt number

    Science.gov (United States)

    Clay, M. P.; Buaria, D.; Gotoh, T.; Yeung, P. K.

    2017-10-01

    A new dual-communicator algorithm with very favorable performance characteristics has been developed for direct numerical simulation (DNS) of turbulent mixing of a passive scalar governed by an advection-diffusion equation. We focus on the regime of high Schmidt number (S c), where because of low molecular diffusivity the grid-resolution requirements for the scalar field are stricter than those for the velocity field by a factor √{ S c }. Computational throughput is improved by simulating the velocity field on a coarse grid of Nv3 points with a Fourier pseudo-spectral (FPS) method, while the passive scalar is simulated on a fine grid of Nθ3 points with a combined compact finite difference (CCD) scheme which computes first and second derivatives at eighth-order accuracy. A static three-dimensional domain decomposition and a parallel solution algorithm for the CCD scheme are used to avoid the heavy communication cost of memory transposes. A kernel is used to evaluate several approaches to optimize the performance of the CCD routines, which account for 60% of the overall simulation cost. On the petascale supercomputer Blue Waters at the University of Illinois, Urbana-Champaign, scalability is improved substantially with a hybrid MPI-OpenMP approach in which a dedicated thread per NUMA domain overlaps communication calls with computational tasks performed by a separate team of threads spawned using OpenMP nested parallelism. At a target production problem size of 81923 (0.5 trillion) grid points on 262,144 cores, CCD timings are reduced by 34% compared to a pure-MPI implementation. Timings for 163843 (4 trillion) grid points on 524,288 cores encouragingly maintain scalability greater than 90%, although the wall clock time is too high for production runs at this size. Performance monitoring with CrayPat for problem sizes up to 40963 shows that the CCD routines can achieve nearly 6% of the peak flop rate. The new DNS code is built upon two existing FPS and CCD codes

  7. Computers and students as instructional partners: The role of simulation feedback in collaborative argumentation

    Science.gov (United States)

    Diehl, Christine Lee

    Drawing from research that investigates reasoning with a theory-based computational model, we have developed a computer learning environment, Convince Me, designed to help students create and evaluate arguments. Laboratory studies indicate that students working individually with Convince Me to build arguments obtain benefits that are often associated with collaborative activity. The current study investigates whether these benefits can be attributed to, among other things, the feedback from Convince Me's simulation model: Does the program serve as a "computer partner" in place of a "student partner?" Students in four ninth-grade Integrated Science classes used Convince Me either with or without model feedback. Half of the students in each group worked individually with the program, and half worked in pairs. A fifth class served as a control group whose students worked individually with paper-and-pencil exercises. Students completed a curriculum on waste management, during which they constructed arguments that evaluated waste disposal methods. Their performance in constructing arguments was assessed, they were tested for knowledge of the principles of scientific argumentation, and they were asked to evaluate the representations and support features of the Convince Me program. The results highlight how the program's representations provide a structure for collaborative argument building and mediate communication among students, prompting pairs of students to engage in shared explanatory and reflective activity. This resulted in better performance in the argument activities and increased knowledge of scientific argumentation for students working in pairs. The results show that working with feedback from the simulation model also increased student performance by challenging their argument representations and encouraging reflection on argument structure. Finally, the results suggest that feedback from the model and collaboration are not identical in the types of

  8. Dosimetry in radiotherapy and brachytherapy by Monte-Carlo GATE simulation on computing grid; Dosimetrie en radiotherapie et curietherapie par simulation Monte-Carlo GATE sur grille informatique

    Energy Technology Data Exchange (ETDEWEB)

    Thiam, Ch.O

    2007-10-15

    Accurate radiotherapy treatment requires the delivery of a precise dose to the tumour volume and a good knowledge of the dose deposit to the neighbouring zones. Computation of the treatments is usually carried out by a Treatment Planning System (T.P.S.) which needs to be precise and fast. The G.A.T.E. platform for Monte-Carlo simulation based on G.E.A.N.T.4 is an emerging tool for nuclear medicine application that provides functionalities for fast and reliable dosimetric calculations. In this thesis, we studied in parallel a validation of the G.A.T.E. platform for the modelling of electrons and photons low energy sources and the optimized use of grid infrastructures to reduce simulations computing time. G.A.T.E. was validated for the dose calculation of point kernels for mono-energetic electrons and compared with the results of other Monte-Carlo studies. A detailed study was made on the energy deposit during electrons transport in G.E.A.N.T.4. In order to validate G.A.T.E. for very low energy photons (<35 keV), three models of radioactive sources used in brachytherapy and containing iodine 125 (2301 of Best Medical International; Symmetra of Uro- Med/Bebig and 6711 of Amersham) were simulated. Our results were analyzed according to the recommendations of task group No43 of American Association of Physicists in Medicine (A.A.P.M.). They show a good agreement between G.A.T.E., the reference studies and A.A.P.M. recommended values. The use of Monte-Carlo simulations for a better definition of the dose deposited in the tumour volumes requires long computing time. In order to reduce it, we exploited E.G.E.E. grid infrastructure where simulations are distributed using innovative technologies taking into account the grid status. Time necessary for the computing of a radiotherapy planning simulation using electrons was reduced by a factor 30. A Web platform based on G.E.N.I.U.S. portal was developed to make easily available all the methods to submit and manage G

  9. Optimising the vertical grid for numerical simulations of the Black Sea dynamics

    Science.gov (United States)

    Shapiro, G. I.; Pickering, J.; Luneva, M. V.

    2012-04-01

    In contrast to analytical methods which deal with continuous functions, solutions obtained using numerical methods depend on the type of discretisation used in the model. It is known that not only different classes of discretisation (such as finite difference, finite element, finite volume etc.) result in different numerical outputs but also variations within the same class may have significant effect on the quality of simulation. When it comes to discretization in the vertical, examples include z- or terrain-following coordinate systems all of which have their advantages and disadvantages. The aim of this study is to identify how sensitive modelling results are to changes in the vertical grid structure, under condition that all other parameters, both physical (e.g. initial temperature and salinity field and meteo forcing) and numerical ( e.g. time step, horizontal resolution, number of vertical layers) are kept the same. The simulations were carried out using the NEMO ocean model at 6 km resolution for the Black Sea which has both deep (more than 2 km) areas and an extensive (hundreds of kilometres) continental shelf. The shelf break, where the slope changes abruptly, is traditionally a difficult location for many types of models. The terrain-following coordinate systems (such as s- and sigma-) are prone the pressure gradient (PG) errors, while z-coordinate systems create a serrated edge near the bottom. Some improvements are provided by z-coordinates with partial steps; however this approach has its own limitations. In this study we compare 4 vertical coordinate system: z-, s-, hybrid (s- on top of z-), and advanced hybrid (modified s- on top of z-). The latter two are the new systems, not yet implemented in the standard NEMO code and developed specifically for this study. The hybrid system uses s-coordinates in the upper layer of the ocean, from the sea surface to the depth of the shelf break and z-coordinate below this level. Such configuration minimizes the PG

  10. 离网风电-网电互补的模拟供电试验%Supply Simulation Experimental Research Based on Integration of Off-grid Wind Power and Grid Power

    Institute of Scientific and Technical Information of China (English)

    叶会华; 杨龙; 高滨; 甄宏巅; 赵旭

    2014-01-01

    以离网风电-网电互补的抽油机供电关键技术研究为理论基础,确立了离网风-网互补供电系统模拟试验研究方案;通过建立模拟试验平台,确定了风力发电机模拟发电系统,并基于计算机设计了一套完整的信号测量与控制系统;进行了模拟供电的试验研究。%Based on the core technology research of complementary supply system of off-grid wind power and grid power, this paper presented a new simulation research design of mutual complementary system between off-grid wind power and grid power;the authors set up a simulation platform so as to design a wind generator simulation system, meanwhile, a new signal testing and control system was designed by computers, which was used to carry out an experimental research of simu-lation power.

  11. ImmunoGrid, an integrative environment for large-scale simulation of the immune system for vaccine discovery, design and optimization

    DEFF Research Database (Denmark)

    Pappalardo, F.; Halling-Brown, M. D.; Rapin, Nicolas;

    2009-01-01

    Vaccine research is a combinatorial science requiring computational analysis of vaccine components, formulations and optimization. We have developed a framework that combines computational tools for the study of immune function and vaccine development. This framework, named ImmunoGrid combines...... conceptual models of the immune system, models of antigen processing and presentation, system-level models of the immune system, Grid computing, and database technology to facilitate discovery, formulation and optimization of vaccines. ImmunoGrid modules share common conceptual models and ontologies....... The ImmunoGrid portal offers access to educational simulators where previously defined cases can be displayed, and to research simulators that allow the development of new, or tuning of existing, computational models. The portal is accessible at http://www.w3.org....

  12. NEMO. A novel techno-economic tool suite for simulating and optimizing solutions for grid integration of electric vehicles and charging stations

    Energy Technology Data Exchange (ETDEWEB)

    Erge, Thomas; Stillahn, Thies; Dallmer-Zerbe, Kilian; Wille-Haussmann, Bernhard [Frauenhofer Institut for Solar Energy Systems ISE, Freiburg (Germany)

    2013-07-01

    With an increasing use of electric vehicles (EV) grid operators need to predict energy flows depending on electromobility use profiles to accordingly adjust grid infrastructure and operation control accordingly. Tools and methodologies are required to characterize grid problems resulting from the interconnection of EV with the grid. The simulation and optimization tool suite NEMO (Novel E-MObility grid model) was developed within a European research project and is currently being tested using realistic showcases. It is a combination of three professional tools. One of the tools aims at a combined techno-economic design and operation, primarily modeling plants on contracts or the spot market, at the same time participating in balancing markets. The second tool is designed for planning grid extension or reinforcement while the third tool is mainly used to quickly discover potential conflicts of grid operation approaches through load flow analysis. The tool suite is used to investigate real showcases in Denmark, Germany and the Netherlands. First studies show that significant alleviation of stress on distribution grid lines could be achieved by few but intelligent restrictions to EV charging procedures.

  13. Optimization and Simulation of Collaborative Networks for Sustainable Production and Transportation

    DEFF Research Database (Denmark)

    Liotta, Giacomo; Kaihara, Toshiya; Stecca, Giuseppe

    2016-01-01

    Complex and delocalized manufacturing industries require high levels of integration between production and transportation in order to effectively implement lean and agile operations. There are, however, limitations in research and applications simultaneously embodying further sustainability...... dimensions. This paper presents a methodological framework based on optimization and simulation to integrate aggregate optimized plans for production and multimodal transportation with detailed dynamic distribution plans affected by demand uncertainty. The objective function of the optimization model...... considers supply, production, transportation, and CO2 emission costs, as well as collaboration over the multimodal network. Bill-of-materials and capacity constraints are included. A feedback between simulation and optimization is used to plan requirements for materials and components. Computational...

  14. Efficient triple-grid multiscale finite element method for 3D groundwater flow simulation in heterogeneous porous media

    Science.gov (United States)

    Xie, Yifan; Wu, Jichun; Nan, Tongchao; Xue, Yuqun; Xie, Chunhong; Ji, Haifeng

    2017-03-01

    In this paper, an efficient triple-grid multiscale finite element method (ETMSFEM) is proposed for 3D groundwater simulation in heterogeneous porous media. The main idea of this method is to employ new 3D linear base functions and the domain decomposition technique to solve the local reduced elliptical problem, thereby simplifying the base function construction process and improving the efficiency. Furthermore, by using the ETMSFEM base functions, this method can solve Darcy's equation with high efficiency to obtain a continuous velocity field. Therefore, this method can considerably reduce the computational cost of solving for heads and velocities, which is crucial for large-scale 3D groundwater simulations. In the application section, we present numerical examples to compare the ETMSFEM with several classical methods to demonstrate its efficiency and effectiveness.

  15. A refined sub-grid model for black hole accretion and AGN feedback in large cosmological simulations

    CERN Document Server

    Bachmann, Lisa K; Hirschmann, Michaela; Prieto, M Almudena; Remus, Rhea-Silvia

    2014-01-01

    In large scale cosmological hydrodynamic simulations simplified sub-grid models for gas accretion onto black holes and AGN feedback are commonly used. Such models typically depend on various free parameters, which are not well constrained. We present a new advanced model containing a more detailed description of AGN feedback, where those parameters reflect the results of recent observations. The model takes the dependency of these parameters on the black hole properties into account and describes a continuous transition between the feedback processes acting in the so-called radio-mode and quasar-mode. In addition, we implement a more detailed description of the accretion of gas onto black holes by distinguishing between hot and cold gas accretion. Our new implementations prevent black holes from gaining too much mass, particularly at low redshifts so that our simulations are now very successful in reproducing the observed present-day black hole mass function. Our new model also suppresses star formation in ma...

  16. Transient analysis of a grid connected wind driven induction generator using a real-time simulation platform

    Energy Technology Data Exchange (ETDEWEB)

    Ouhrouche, Mohand [Department of Applied Sciences, University of Quebec at Chicoutimi, Quebec, G7H2B1 (Canada)

    2009-03-15

    Due to its simple construction, ruggedness and low cost, the induction generator driven by a wind turbine and feeding power to the grid appears to be an attractive solution to the problem of growing energy demand in the context of environmental issues. This paper investigates the integration of such a system into the main utility using RT-Lab trademark (Trademark of Opal-RT Technologies) software package running on a simple off-the-shelf PC. This real-time simulation platform is now adopted by many high-tech industries as a real-time laboratory package for rapid control prototyping and for Hardware-in-the-Loop applications. Real-time digital simulation results obtained during contingencies, such as islanding and unbalanced faults are presented and analysed. (author)

  17. Promoting interprofessional collaboration in oncology through a teamwork skills simulation programme.

    Science.gov (United States)

    James, Ted A; Page, Jenna S; Sprague, Julian

    2016-07-01

    Outcomes in clinical oncology can be improved when care is delivered by high-performance teams. The purpose of the initiative described in this article was to develop interprofessional team training opportunities using simulated cancer care scenarios to enhance collaborative practice skills within clinical oncology. Scenarios were developed based on internal needs assessment and review of patient safety data. Paired teams of haematology-oncology nurses and fellows completed the patient management scenarios, followed by debriefing and performance feedback. Research design consisted of an observational case study and questionnaire of participants in a cross-sectional analysis. Twenty-three learners participated in two separate sessions. All participants responded with scores of 4-5 on a 5-point Likert scale regarding the perceived value of the training programme and its effectiveness in developing skills in teamwork and communication. Simulation-based team training scenarios were successfully implemented into an interprofessional curriculum for haematology-oncology nurses and fellows. Participants valued the experience and indicated that they acquired new knowledge, skills, and attitudes to enhance interprofessional collaboration in cancer care. These types of training programmes have the potential to transform cancer care by creating high-performing teams resulting in improved patient outcomes, enhanced clinical effectiveness, and higher levels of satisfaction among patients, families, and healthcare providers.

  18. EXPRESS--Examining Pediatric Resuscitation Education Using Simulation and Scripting. The birth of an international pediatric simulation research collaborative--from concept to reality.

    Science.gov (United States)

    Cheng, Adam; Hunt, Elizabeth A; Donoghue, Aaron; Nelson, Kristen; Leflore, Judy; Anderson, JoDee; Eppich, Walter; Simon, Robert; Rudolph, Jenny; Nadkarni, Vinay

    2011-02-01

    Over the past decade, medical simulation has evolved into an essential component of pediatric resuscitation education and team training. Evidence to support its value as an adjunct to traditional methods of education is expanding; however, large multicenter studies are very rare. Simulation-based researchers currently face many challenges related to small sample sizes, poor generalizability, and paucity of clinically proven and relevant outcome measures. The Examining Pediatric Resuscitation Education Using Simulation and Scripting (EXPRESS) pediatric simulation research collaborative was formed in an attempt to directly address and overcome these challenges. The primary mission of the EXPRESS collaborative is to improve the delivery of medical care to critically ill children by answering important research questions pertaining to pediatric resuscitation and education and is focused on using simulation either as a key intervention of interest or as the outcome measurement tool. Going forward, the collaborative aims to expand its membership internationally and collectively identify pediatric resuscitation and simulation-based research priorities and use these to guide future projects. Ultimately, we hope that with innovative and high-quality research, the EXPRESS pediatric simulation research collaborative will help to build momentum for simulation-based research on an international level. Copyright © 2011 Society for Simulation in Healthcare

  19. Exploring residents’ spontaneous collaborative skills in a simulated setting context: an exploratory study on CanMEDS collaborator role

    Directory of Open Access Journals (Sweden)

    Ouellet K

    2016-07-01

    Full Text Available Kathleen Ouellet,1 Robert Sabbagh,2 Linda Bergeron,3 Sandeep Kumar Mayer,2 Christina St-Onge4 1Center for Health Profession Education, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 2Department of Surgery, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3Research Chair in Medical Education, Paul Grand’Maison of the Société des médecins, Université de Sherbrooke, 4Department of Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada Background: Collaboration is an important competence to be acquired by residents. Although improving residents’ collaboration via interprofessional education has been investigated in many studies, little is known about the residents’ spontaneous collaborative behavior. The purpose of this exploratory study was to describe how residents spontaneously collaborate.Methods: Seven first-year residents (postgraduate year 1; three from family medicine and one each from ear, nose, and throat, obstetrics/gynecology, general surgery, and orthopedic surgery participated in two collaborative meetings with actors performing the part of other health ­professionals (ie, occupational therapist, physiotherapist, nurse, or social worker. Both meetings were built around an issue or conflict with the patients’ families reported by one professional. The residents were required to lead the meeting to collect proper information to reach a joint decision. Two team members analyzed the video recordings of the meetings using an emerging-theme qualitative methodology.Results: Although the residents spontaneously knew how to successfully communicate with other professionals, they seemed to struggle with the patient-centered approach and the shared decision-making process.Discussion: Even if the residents performed communication-wise in their collaborative role, they seemed to have perceived themselves as decision makers instead of

  20. Modeling and simulating an electrical grid subsystem for power balance analysis

    DEFF Research Database (Denmark)

    Totu, Luminita Cristiana; Leth, John-Josef; Wisniewski, Rafal

    2012-01-01

    We present an approach for power balance analysis in Smart Grids where the physical behavior of different electrical devices is modeled at unit level, and the collective load and generation curves can later be obtained by aggregation. In this way, new behaviors, flexibilities and intelligent...... strategies for power consumption and generation can be easily introduced at the user-level and the system-level impact analyzed on the aggregated profiles. The future aim is to investigate bottom-up balancing strategies, where units with a flexible energy band can react independently to power balance signals...

  1. Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

    Science.gov (United States)

    Christon, Mark A.; Lu, Roger; Bakosi, Jozsef; Nadiga, Balasubramanya T.; Karoutas, Zeses; Berndt, Markus

    2016-10-01

    Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuel rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid-structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuating structural forces, and the nonlinear transient dynamics analysis of the fuel rod. Ultimately, the methods developed here, can be used, in conjunction with operational management, to improve reactor core designs in which fuel rod failures are minimized or potentially eliminated. Robustness of the behavior of both the structural forces computed from the turbulent flow simulations and the results from the transient dynamics analyses highlight the progress made towards achieving a predictive simulation capability for the GTRF problem.

  2. Proceedings of joint meeting of the 6th simulation science symposium and the NIFS collaboration research 'large scale computer simulation'

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-03-01

    Joint meeting of the 6th Simulation Science Symposium and the NIFS Collaboration Research 'Large Scale Computer Simulation' was held on December 12-13, 2002 at National Institute for Fusion Science, with the aim of promoting interdisciplinary collaborations in various fields of computer simulations. The present meeting attended by more than 40 people consists of the 11 invited and 22 contributed papers, of which topics were extended not only to fusion science but also to related fields such as astrophysics, earth science, fluid dynamics, molecular dynamics, computer science etc. (author)

  3. Stimulating reflective practice using collaborative reflective training in breaking bad news simulations.

    Science.gov (United States)

    Kim, Lana; Hernandez, Barbara Couden; Lavery, Adrian; Denmark, T Kent

    2016-06-01

    Medical simulation has long been used as a way to immerse trainees in realistic practice scenarios to help them consolidate their formal medical knowledge and develop teamwork, communication, and technical skills. Debriefing is regarded as a critical aspect of simulation training. With a skilled debriefing facilitator, trainees are able to go beyond a rote review of the skills and steps taken to explore their internal process and self-reflect on how their experience during the simulation shaped their decision making and behavior. However, the sense of vulnerability is an aspect of experiential training that can raise a trainee's defensiveness. Anxiety increases when trainees anticipate being evaluated for their performance, or when the simulation scenario pertains to complex interpersonal activities such as learning how to break bad news (BBN), a commonly encountered aspect of medical practice with inadequate training. Thus, collaborative reflective training (CRT), developed out of ideas based in family therapy, was designed as an approach for facilitating open dialogue and greater self-reflection while receiving training in BBN. This article will discuss the conceptual framework of CRT, explain how it was developed, and describe the nature of how it was used with a team of neonatology and pediatric fellows and medical family therapy interns. (PsycINFO Database Record

  4. Impact of Sub-grid Soil Textural Properties on Simulations of Hydrological Fluxes at the Continental Scale Mississippi River Basin

    Science.gov (United States)

    Kumar, R.; Samaniego, L. E.; Livneh, B.

    2013-12-01

    Knowledge of soil hydraulic properties such as porosity and saturated hydraulic conductivity is required to accurately model the dynamics of near-surface hydrological processes (e.g. evapotranspiration and root-zone soil moisture dynamics) and provide reliable estimates of regional water and energy budgets. Soil hydraulic properties are commonly derived from pedo-transfer functions using soil textural information recorded during surveys, such as the fractions of sand and clay, bulk density, and organic matter content. Typically large scale land-surface models are parameterized using a relatively coarse soil map with little or no information on parametric sub-grid variability. In this study we analyze the impact of sub-grid soil variability on simulated hydrological fluxes over the Mississippi River Basin (≈3,240,000 km2) at multiple spatio-temporal resolutions. A set of numerical experiments were conducted with the distributed mesoscale hydrologic model (mHM) using two soil datasets: (a) the Digital General Soil Map of the United States or STATSGO2 (1:250 000) and (b) the recently collated Harmonized World Soil Database based on the FAO-UNESCO Soil Map of the World (1:5 000 000). mHM was parameterized with the multi-scale regionalization technique that derives distributed soil hydraulic properties via pedo-transfer functions and regional coefficients. Within the experimental framework, the 3-hourly model simulations were conducted at four spatial resolutions ranging from 0.125° to 1°, using meteorological datasets from the NLDAS-2 project for the time period 1980-2012. Preliminary results indicate that the model was able to capture observed streamflow behavior reasonably well with both soil datasets, in the major sub-basins (i.e. the Missouri, the Upper Mississippi, the Ohio, the Red, and the Arkansas). However, the spatio-temporal patterns of simulated water fluxes and states (e.g. soil moisture, evapotranspiration) from both simulations, showed marked

  5. A 12-year (1987-1998) Ensemble Simulation of the US Climate with a Variable Resolution Stretched Grid GCM

    Science.gov (United States)

    Fox-Rabinovitz, Michael S.; Takacs, Lawrence L.; Govindaraju, Ravi C.

    2002-01-01

    The variable-resolution stretched-grid (SG) GEOS (Goddard Earth Observing System) GCM has been used for limited ensemble integrations with a relatively coarse, 60 to 100 km, regional resolution over the U.S. The experiments have been run for the 12-year period, 1987-1998, that includes the recent ENSO cycles. Initial conditions 1-2 days apart are used for ensemble members. The goal of the experiments is analyzing the long-term SG-GCM ensemble integrations in terms of their potential in reducing the uncertainties of regional climate simulation while producing realistic mesoscales. The ensemble integration results are analyzed for both prognostic and diagnostic fields. A special attention is devoted to analyzing the variability of precipitation over the U.S. The internal variability of the SG-GCM has been assessed. The ensemble means appear to be closer to the verifying analyses than the individual ensemble members. The ensemble means capture realistic mesoscale patterns, especially those of induced by orography. Two ENSO cycles have been analyzed in terms their impact on the U.S. climate, especially on precipitation. The ability of the SG-GCM simulations to produce regional climate anomalies has been confirmed. However, the optimal size of the ensembles depending on fine regional resolution used, is still to be determined. The SG-GCM ensemble simulations are performed as a preparation or a preliminary stage for the international SGMIP (Stretched-Grid Model Intercomparison Project) that is under way with participation of the major centers and groups employing the SG-approach for regional climate modeling.

  6. Developing a grounded theory for interprofessional collaboration acquisition using facilitator and actor perspectives in simulated wilderness medical emergencies.

    Science.gov (United States)

    Smith, Heather A; Reade, Maurianne; Marr, Marion; Jeeves, Nicholas

    2017-01-01

    Interprofessional collaboration is a complex process that has the potential to transform patient care for the better in urban, rural and remote healthcare settings. Simulation has been found to improve participants' interprofessional competencies, but the mechanisms by which interprofessionalism is learned have yet to be understood. A rural wilderness medicine conference (WildER Med) in northern Ontario, Canada with simulated medical scenarios has been demonstrated to be effective in improving participants' collaboration without formal interprofessional education (IPE) curriculum. Interprofessionalism may be taught through rural and remote medical simulation, as done in WildER Med where participants' interprofessional competencies improved without any formal IPE curriculum. This learning may be attributed to the informal and hidden curriculum. Understanding the mechanism by which this rural educational experience contributed to participants' learning to collaborate requires insight into the events before, during and after the simulations. The authors drew upon feedback from facilitators and patient actors in one-on-one interviews to develop a grounded theory for how collaboration is taught and learned. Sharing emerged as the core concept of a grounded theory to explain how team members acquired interprofessional collaboration competencies. Sharing was enacted through the strategies of developing common goals, sharing leadership, and developing mutual respect and understanding. Further analysis of the data and literature suggests that the social wilderness environment was foundational in enabling sharing to occur. Medical simulations in other rural and remote settings may offer an environment conducive to collaboration and be effective in teaching collaboration. When designing interprofessional education, health educators should consider using emergency response teams or rural community health teams to optimize the informal and hidden curriculum contributing to

  7. IGMESH: A convenient irregular-grid-based pre- and post-processing tool for TOUGH2 simulator

    Science.gov (United States)

    Hu, Litang; Zhang, Keni; Cao, Xiaoyuan; Li, Yi; Guo, Chaobin

    2016-10-01

    As a powerful simulator with input files in fixed-format formats, the capabilities of TOUGH2 simulator urge programmers to develop the pre- and post-processing programs. A new program (IGMESH) with Graphical User Interface (GUI) is introduced. The elements for spatial discrezation are classified into domain bound, boundary for refinement, well, fault, drift and free point, which will be discreted into a series of points. The Voronoi tessellation method is employed to generate Voronoi diagrams in the plane and the relation of neighbor points in a polygon is obtained from the geometric relationship of Voronoi diagrams. Three-dimensional mesh is built based on top elevation and thickness of each model layer. IGMESH provides functions for rock type assignment, boundary conditions, interpolation method of elevation and thickness, simulation results conversion and visualization with TECPLOT software. The case studies in the Beishan area demonstrate the applicability of the approach. IGMESH software has shown to be adequate to build quasi-3D unstructured grids from the beginning of numerical model build to the results analysis, and thus will facilitate the application of TOUGH2 simulator.

  8. Atmospheric Properties from the 2006 Niamey Deployment and Climate Simulation with a Geodesic Grid Coupled Climate Model Fourth Quarter 2008

    Energy Technology Data Exchange (ETDEWEB)

    JH Mather; DA Randall; CJ Flynn

    2008-09-30

    In 2008, the Atmospheric Radiation Measurement (ARM) Program and the Climate Change Prediction Program (CCPP) have been asked to produce joint science metrics. For CCPP, the metrics will deal with a decade-long control simulation using geodesic grid-coupled climate model. For ARM, the metrics will deal with observations associated with the 2006 deployment of the ARM Mobile Facility (AMF) to Niamey, Niger. Specifically, ARM has been asked to deliver data products for Niamey that describe cloud, aerosol, and dust properties. The first quarter milestone was the initial formulation of the algorithm for retrieval of these properties. The second quarter milestone included the time series of ARM-retrieved cloud properties and a year-long CCPP control simulation. The third quarter milestone included the time series of ARM-retrieved aerosol optical depth and a three-year CCPP control simulation. This final fourth quarter milestone includes the time-series of aerosol and dust properties and a decade-long CCPP control simulation.

  9. Hadron Therapy: A study on Grid Databases and Monte Carlo Simulations

    CERN Document Server

    Charitonidis, Nikolaos; Silari, M; Gazis, E

    2009-01-01

    Hadron therapy is a novel technique of cancer radiation therapy using beams of energetic protons, neutrons, or positive ions for cancer treatment. In the context of this thesis, two individual projects have been performed, both of them having a direct relevance with Hadron Therapy. The first part consists of a literature analysis of six different projects. The common characteristic of these projects is that they are dealing with the distribution of large amounts of data, among geographically distributed user teams. The solutions proposed are exploiting either Grid, or parallel databases implementations, or combinations of these two technologies. The objectives of the authors, the technical details of the implementations as well as the security issues of each proposal, have been extracted from the original papers, and are being juxtapositioned. Comparison tables between the different software and hardware choices of each implementation have been produced, while the benefits or the drawbacks of each choice, tha...

  10. Hadron Therapy: A study on Grid Databases and Monte Carlo Simulations

    CERN Document Server

    Charitonidis, Nikolaos; Silari, M; Gazis, E

    2009-01-01

    Hadron therapy is a novel technique of cancer radiation therapy using beams of energetic protons, neutrons, or positive ions for cancer treatment. In the context of this thesis, two individual projects have been performed, both of them having a direct relevance with Hadron Therapy. The first part consists of a literature analysis of six different projects. The common characteristic of these projects is that they are dealing with the distribution of large amounts of data, among geographically distributed user teams. The solutions proposed are exploiting either Grid, or parallel databases implementations, or combinations of these two technologies. The objectives of the authors, the technical details of the implementations as well as the security issues of each proposal, have been extracted from the original papers, and are being juxtapositioned. Comparison tables between the different software and hardware choices of each implementation have been produced, while the benefits or the drawbacks of each choice, tha...

  11. STATICS ANALYSIS AND OPENGL BASED 3D SIMULATION OF COLLABORATIVE RECONFIGURABLE PLANETARY ROBOTS

    Institute of Scientific and Technical Information of China (English)

    Zhang Zheng; Ma Shugen; Li Bin; Zhang Liping; Cao Binggang

    2006-01-01

    Objective To study mechanics characteristics of two cooperative reconfigurable planetary robots when they get across an obstacle, and to find out the relationship between the maximum height of a stair with the configuration of the two-robot, and to find some restrictions of kinematics for the cooperation. Methods Multirobot cooperation theory is used in the whole study process. Inverse kinematics of the robot is used to form a desired configuration in the cooperation process. Static equations are established to analyze the relations between the friction factor, the configuration of robots and the maximum height of a stair. Kinematics analysis is used to find the restrictions of the two collaborative robots in position, velocity and acceleration. Results 3D simulation shows that the two cooperative robots can climb up a stair under the condition of a certain height and a certain friction factor between robot wheel and the surface of the stair. Following the restrictions of kinematics, the climbing mission is fulfilled successfully and smoothly. Conclusion The maximum height of a stair, which the two cooperative robots can climb up, is involved in the configuration of robots, friction factor between the stair and the robots. The most strict restriction of the friction factor does not appear in the horizontal position. In any case, the maximum height is smaller than half of the distance between the centroid of robot1 with the centroid of robot2. However, the height can be higher than the radius of one robot wheel, which profit from the collaboration.

  12. Three-Dimensional General-Relativistic Hydrodynamic Simulations of Binary Neutron Star Coalescence and Stellar Collapse with Multipatch Grids

    CERN Document Server

    Reisswig, C; Ott, C D; Abdikamalov, E; Moesta, P; Pollney, D; Schnetter, E

    2013-01-01

    We present a new three-dimensional general-relativistic hydrodynamic evolution scheme coupled to dynamical spacetime evolutions which is capable of efficiently simulating stellar collapse, isolated neutron stars, black hole formation, and binary neutron star coalescence. We make use of a set of adapted curvi-linear grids (multipatches) coupled with flux-conservative cell-centered adaptive mesh refinement. This allows us to significantly enlarge our computational domains while still maintaining high resolution in the gravitational-wave extraction zone, the exterior layers of a star, or the region of mass ejection in merging neutron stars. The fluid is evolved with a high-resolution shock capturing finite volume scheme, while the spacetime geometry is evolved using fourth-order finite differences. We employ a multi-rate Runge-Kutta time integration scheme for efficiency, evolving the fluid with second-order and the spacetime geometry with fourth-order integration, respectively. We validate our code by a number ...

  13. Telematics-based online client-server/client collaborative environment for radiotherapy planning simulations.

    Science.gov (United States)

    Kum, Oyeon

    2007-11-01

    Customized cancer radiation treatment planning for each patient is very useful for both a patient and a doctor because it provides the ability to deliver higher doses to a more accurately defined tumor and at the same time lower doses to organs at risk and normal tissues. This can be realized by building an accurate planning simulation system to provide better treatment strategies based on each patient's tomographic data such as CT, MRI, PET, or SPECT. In this study, we develop a real-time online client-server/client collaborative environment between the client (health care professionals or hospitals) and the server/client under a secure network using telematics (the integrated use of telecommunications and medical informatics). The implementation is based on a point-to-point communication scheme between client and server/client following the WYSIWIS (what you see is what I see) paradigm. After uploading the patient tomographic data, the client is able to collaborate with the server/client for treatment planning. Consequently, the level of health care services can be improved, specifically for small radiotherapy clinics in rural/remote-country areas that do not possess much experience or equipment such as a treatment planning simulator. The telematics service of the system can also be used to provide continued medical education in radiotherapy. Moreover, the system is easy to use. A client can use the system if s/he is familiar with the Windows(TM) operating system because it is designed and built based on a user-friendly concept. This system does not require the client to continue hardware and software maintenance and updates. These are performed automatically by the server.

  14. Evaluation of regional climate model simulations versus gridded observed and regional reanalysis products using a combined weighting scheme

    Energy Technology Data Exchange (ETDEWEB)

    Eum, Hyung-Il; Laprise, Rene [University of Quebec at Montreal, ESCER (Etude et Simulation du Climat a l' Echelle Regionale), Montreal, QC (Canada); Gachon, Philippe [University of Quebec at Montreal, ESCER (Etude et Simulation du Climat a l' Echelle Regionale), Montreal, QC (Canada); Environment Canada, Adaptation and Impacts Research Section, Climate Research Division, Montreal, QC (Canada); Ouarda, Taha [University of Quebec, INRS-ETE (Institut National de la Recherche Scientifique, Centre Eau-Terre-Environnement), Quebec, QC (Canada)

    2012-04-15

    This study presents a combined weighting scheme which contains five attributes that reflect accuracy of climate data, i.e. short-term (daily), mid-term (annual), and long-term (decadal) timescales, as well as spatial pattern, and extreme values, as simulated from Regional Climate Models (RCMs) with respect to observed and regional reanalysis products. Southern areas of Quebec and Ontario provinces in Canada are used for the study area. Three series of simulation from two different versions of the Canadian RCM (CRCM4.1.1, and CRCM4.2.3) are employed over 23 years from 1979 to 2001, driven by both NCEP and ERA40 global reanalysis products. One series of regional reanalysis dataset (i.e. NARR) over North America is also used as reference for comparison and validation purpose, as well as gridded historical observed daily data of precipitation and temperatures, both series have been beforehand interpolated on the CRCM 45-km grid resolution. Monthly weighting factors are calculated and then combined into four seasons to reflect seasonal variability of climate data accuracy. In addition, this study generates weight averaged references (WARs) with different weighting factors and ensemble size as new reference climate data set. The simulation results indicate that the NARR is in general superior to the CRCM simulated precipitation values, but the CRCM4.1.1 provides the highest weighting factors during the winter season. For minimum and maximum temperature, both the CRCM4.1.1 and the NARR products provide the highest weighting factors, respectively. The NARR provides more accurate short- and mid-term climate data, but the two versions of the CRCM provide more precise long-term data, spatial pattern and extreme events. Or study confirms also that the global reanalysis data (i.e. NCEP vs. ERA40) used as boundary conditions in the CRCM runs has non-negligible effects on the accuracy of CRCM simulated precipitation and temperature values. In addition, this study demonstrates

  15. A new view on exoplanet transits: Transit of Venus described using three-dimensional solar atmosphere Stagger-grid simulations

    CERN Document Server

    Chiavassa, A; Faurobert, M; Ricort, G; Tanga, P; Magic, Z; Collet, R; Asplund, M

    2015-01-01

    Stellar activity and, in particular, convection-related surface structures, potentially cause fluctuations that can affect the transit light curves. Surface convection simulations can help the interpretation of ToV. We used realistic three-dimensional radiative hydrodynamical simulation of the Sun from the Stagger-grid and synthetic images computed with the radiative transfer code Optim3D to provide predictions for the transit of Venus in 2004 observed by the satellite ACRIMSAT. We computed intensity maps from RHD simulation of the Sun and produced synthetic stellar disk image. We computed the light curve and compared it to the ACRIMSAT observations and also to the light curves obtained with solar surface representations carried out using radial profiles with different limb-darkening laws. We also applied the same spherical tile imaging method to the observations of center-to-limb Sun granulation with HINODE. We managed to explain ACRIMSAT observations of 2004 ToV and showed that the granulation pattern cause...

  16. Simulation and comparison of perturb and observe and incremental conductance MPPT algorithms for solar energy system connected to grid

    Indian Academy of Sciences (India)

    Sachin Vrajlal Rajani; Vivek J Pandya

    2015-02-01

    Solar energy is a clean, green and renewable source of energy. It is available in abundance in nature. Solar cells by photovoltaic action are able to convert the solar energy into electric current. The output power of solar cell depends upon factors such as solar irradiation (insolation), temperature and other climatic conditions. Present commercial efficiency of solar cells is not greater than 15% and therefore the available efficiency is to be exploited to the maximum possible value and the maximum power point tracking (MPPT) with the aid of power electronics to solar array can make this possible. There are many algorithms proposed to realize maximum power point tracking. These algorithms have their own merits and limitations. In this paper, an attempt is made to understand the basic functionality of the two most popular algorithms viz. Perturb and Observe (P & O) algorithm and Incremental conductance algorithm. These algorithms are compared by simulating a 100 kW solar power generating station connected to grid. MATLAB M-files are generated to understand MPPT and its dependency on insolation and temperature. MATLAB Simulink software is used to simulate the MPPT systems. Simulation results are presented to verify these assumptions.

  17. Grid3: An Application Grid Laboratory for Science

    CERN Document Server

    CERN. Geneva

    2004-01-01

    level services required by the participating experiments. The deployed infrastructure has been operating since November 2003 with 27 sites, a peak of 2800 processors, work loads from 10 different applications exceeding 1300 simultaneous jobs, and data transfers among sites of greater than 2 TB/day. The Grid3 infrastructure was deployed from grid level services provided by groups and applications within the collaboration. The services were organized into four distinct "grid level services" including: Grid3 Packaging, Monitoring and Information systems, User Authentication and the iGOC Grid Operatio...

  18. Agglomeration multigrid methods with implicit Runge-Kutta smoothers applied to aerodynamic simulations on unstructured grids

    Science.gov (United States)

    Langer, Stefan

    2014-11-01

    For unstructured finite volume methods an agglomeration multigrid with an implicit multistage Runge-Kutta method as a smoother is developed for solving the compressible Reynolds averaged Navier-Stokes (RANS) equations. The implicit Runge-Kutta method is interpreted as a preconditioned explicit Runge-Kutta method. The construction of the preconditioner is based on an approximate derivative. The linear systems are solved approximately with a symmetric Gauss-Seidel method. To significantly improve this solution method grid anisotropy is treated within the Gauss-Seidel iteration in such a way that the strong couplings in the linear system are resolved by tridiagonal systems constructed along these directions of strong coupling. The agglomeration strategy is adapted to this procedure by taking into account exactly these anisotropies in such a way that a directional coarsening is applied along these directions of strong coupling. Turbulence effects are included by a Spalart-Allmaras model, and the additional transport-type equation is approximately solved in a loosely coupled manner with the same method. For two-dimensional and three-dimensional numerical examples and a variety of differently generated meshes we show the wide range of applicability of the solution method. Finally, we exploit the GMRES method to determine approximate spectral information of the linearized RANS equations. This approximate spectral information is used to discuss and compare characteristics of multistage Runge-Kutta methods.

  19. Evaluation and selection of the ship collaborative design resources based on AHP and genetic and simulated annealing algorithm

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The characteristics of the design resources in the ship collaborative design is described and the hierarchical model for the evaluation of the design resources is established. The comprehensive evaluation of the co-designers for the collaborative design resources has been done from different aspects using Analytic Hierarchy Process (AHP),and according to the evaluation results,the candidates are determined. Meanwhile,based on the principle of minimum cost,and starting from the relations between the design tasks and the corresponding co-designers,the optimizing selection model of the collaborators is established and one novel genetic combined with simulated annealing algorithm is proposed to realize the optimization. It overcomes the defects of the genetic algorithm which may lead to the premature convergence and local optimization if used individually. Through the application of this method in the ship collaborative design system,it proves the feasibility and provides a quantitative method for the optimizing selection of the design resources.

  20. Simulation of collaborative studies for real-time PCR-based quantitation methods for genetically modified crops.

    Science.gov (United States)

    Watanabe, Satoshi; Sawada, Hiroshi; Naito, Shigehiro; Akiyama, Hiroshi; Teshima, Reiko; Furui, Satoshi; Kitta, Kazumi; Hino, Akihiro

    2013-01-01

    To study impacts of various random effects and parameters of collaborative studies on the precision of quantitation methods of genetically modified (GM) crops, we developed a set of random effects models for cycle time values of a standard curve-based relative real-time PCR that makes use of an endogenous gene sequence as the internal standard. The models and data from a published collaborative study for six GM lines at four concentration levels were used to simulate collaborative studies under various conditions. Results suggested that by reducing the numbers of well replications from three to two, and standard levels of endogenous sequence from five to three, the number of unknown samples analyzable on a 96-well PCR plate in routine analyses could be almost doubled, and still the acceptable repeatability RSD (RSDr crops by real-time PCR and their collaborative studies.

  1. Data Grid Implementations

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Reagan W.; Studham, Ronald S.; Rajasekar, Arcot; Watson, Chip; Stockinger, Heinz; Kunszt, Peter; Charlie Catlett and Ian Foster

    2002-02-27

    Data grids link distributed, heterogeneous storage resources into a coherent data management system. From a user perspective, the data grid provides a uniform name space across the underlying storage systems, while supporting retrieval and storage of files. In the high energy physics community, at least six data grids have been implemented for the storage and distribution of experimental data. Data grids are also being used to support projects as diverse as digital libraries (National Library of Medicine Visible Embryo project), federation of multiple astronomy sky surveys (NSF National Virtual Observatory project), and integration of distributed data sets (Long Term Ecological Reserve). Data grids also form the core interoperability mechanisms for creating persistent archives, in which data collections are migrated to new technologies over time. The ability to provide a uniform name space across multiple administration domains is becoming a critical component of national-scale, collaborative projects.

  2. The simulation of localized surface plasmon and surface plasmon polariton in wire grid polarizer integrated on InP substrate for InGaAs sensor

    Directory of Open Access Journals (Sweden)

    Rui Wang

    2015-07-01

    Full Text Available We numerically demonstrate the integration of gold wire grid polarizer on InP substrate for InGaAs polarimetric imaging. The effective spectral range of wire grid polarizer has been designed in 0.8-3 μm according to InGaAs response waveband. The dips in TM transmission are observed due to surface plasmon (SPs significantly damaging polarization performance. To further understand the coupling mechanism between gold wire grid grating and InP, the different contributions of surface plasmon polariton (SPP and localized surface plasmon (LSP to the dips are analyzed. Both transmission and reflectance spectra are simulated at different grating periods and duty cycles by finite-different time-domain (FDTD method. LSP wavelength is located at around 1 μm and sensitive to the specific shape of metal wire. SPP presents higher resonance wavelength closely related to grating period. The simulations of electric field distribution show the same results.

  3. Grid for Earth Science Applications

    Science.gov (United States)

    Petitdidier, Monique; Schwichtenberg, Horst

    2013-04-01

    The civil society at large has addressed to the Earth Science community many strong requirements related in particular to natural and industrial risks, climate changes, new energies. The main critical point is that on one hand the civil society and all public ask for certainties i.e. precise values with small error range as it concerns prediction at short, medium and long term in all domains; on the other hand Science can mainly answer only in terms of probability of occurrence. To improve the answer or/and decrease the uncertainties, (1) new observational networks have been deployed in order to have a better geographical coverage and more accurate measurements have been carried out in key locations and aboard satellites. Following the OECD recommendations on the openness of research and public sector data, more and more data are available for Academic organisation and SMEs; (2) New algorithms and methodologies have been developed to face the huge data processing and assimilation into simulations using new technologies and compute resources. Finally, our total knowledge about the complex Earth system is contained in models and measurements, how we put them together has to be managed cleverly. The technical challenge is to put together databases and computing resources to answer the ES challenges. However all the applications are very intensive computing. Different compute solutions are available and depend on the characteristics of the applications. One of them is Grid especially efficient for independent or embarrassingly parallel jobs related to statistical and parametric studies. Numerous applications in atmospheric chemistry, meteorology, seismology, hydrology, pollution, climate and biodiversity have been deployed successfully on Grid. In order to fulfill requirements of risk management, several prototype applications have been deployed using OGC (Open geospatial Consortium) components with Grid middleware. The Grid has permitted via a huge number of runs to

  4. Collaborative Simulation and Testing of the Superconducting Dipole Prototype Magnet for the FAIR Project

    Institute of Scientific and Technical Information of China (English)

    ZHU Yinfeng; ZHU Zhe; XU Houchang; WU Weiyue

    2012-01-01

    The superconducting dipole prototype magnet of the collector ring for the Facility for Antiproton and Ion Research (FAIR) is an international cooperation project. The collaborative simulation and testing of the developed prototype magnet is presented in this paper. To evaluate the mechanical strength of the coil case during quench, a 3-dimensional (3D) electromagnetic (EM) model was developed based on the solid97 magnetic vector element in the ANSYS commercial software, which includes the air region, coil and yoke. EM analysis was carried out with a peak operating current at 278 A. Then, the solid97 element was transferred into the solid185 element, the coupled analysis was switched from electromagnetic to structural, and the finite element model for the coil case and glass-fiber reinforced composite (G10) spacers was established by the ANSYS Parametric Design Language based on the 3D model from the CATIA V5 software. However, to simulate the friction characteristics inside the coil case, the conta173 surface-to-surface contact element was established. The results for the coil case and G10 spacers show that they are safe and have sufficient strength, on the basis of testing in discharge and quench scenarios.

  5. Collaborative Simulation and Testing of the Superconducting Dipole Prototype Magnet for the FAIR Project

    Science.gov (United States)

    Zhu, Yinfeng; Zhu, Zhe; Xu, Houchang; Wu, Weiyue

    2012-08-01

    The superconducting dipole prototype magnet of the collector ring for the Facility for Antiproton and Ion Research (FAIR) is an international cooperation project. The collaborative simulation and testing of the developed prototype magnet is presented in this paper. To evaluate the mechanical strength of the coil case during quench, a 3-dimensional (3D) electromagnetic (EM) model was developed based on the solid97 magnetic vector element in the ANSYS commercial software, which includes the air region, coil and yoke. EM analysis was carried out with a peak operating current at 278 A. Then, the solid97 element was transferred into the solid185 element, the coupled analysis was switched from electromagnetic to structural, and the finite element model for the coil case and glass-fiber reinforced composite (G10) spacers was established by the ANSYS Parametric Design Language based on the 3D model from the CATIA V5 software. However, to simulate the friction characteristics inside the coil case, the conta173 surface-to-surface contact element was established. The results for the coil case and G10 spacers show that they are safe and have sufficient strength, on the basis of testing in discharge and quench scenarios.

  6. Eagle Racing: Addressing Corporate Collaboration Challenges through an Online Simulation Game

    Science.gov (United States)

    Angehrn, Albert A.; Maxwell, Katrina

    2009-01-01

    Effective collaboration is necessary for corporation-wide learning, knowledge exchange, and innovation. However, it is difficult to create a corporate culture that encourages collaboration; the complexity of such collaboration is increased substantially by the diverse and distributed nature of knowledge sources and decision makers in the global…

  7. Simulating space-time uncertainty in continental-scale gridded precipitation fields for agrometeorological modelling

    NARCIS (Netherlands)

    Wit, de A.J.W.; Bruin, de S.

    2006-01-01

    Previous analyses of the effects of uncertainty in precipitation fields on the output of EU Crop Growth Monitoring System (CGMS) demonstrated that the influence on simulated crop yield was limited at national scale, but considerable at local and regional scales. We aim to propagate uncertainty due t

  8. Discrete energy conservation in numerical flow simulations with local grid refinement

    NARCIS (Netherlands)

    Kort, Alderik Jan Albertus

    2016-01-01

    The behaviour of fluids is studied through the Navier-Stokes equations. Computer models are used to solve these equations in practical situations. However, for many practically interesting applications, computer simulations still take too much time to be useful. To increase the feasibility of simula

  9. Simulated Switching Transients in the External Grid of Walney Offshore Wind Farm

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Johnsen, D. T.; Soerensen, T.

    2011-01-01

    . These switching operations were simulated using the EMT software PSCAD/EMTDC A number of parameters were varied in order to determine the most critical transients. Based on the results, it was concluded that the worst line-to-line transient overvoltage occurred in the DC05 and EF06 turbines, when a 25km cable...

  10. F-16XL Hybrid Reynolds-Averaged Navier-Stokes/Large Eddy Simulation on Unstructured Grids

    Science.gov (United States)

    Park, Michael A.; Abdol-Hamid, Khaled S.; Elmiligui, Alaa

    2015-01-01

    This study continues the Cranked Arrow Wing Aerodynamics Program, International (CAWAPI) investigation with the FUN3D and USM3D flow solvers. CAWAPI was established to study the F-16XL, because it provides a unique opportunity to fuse fight test, wind tunnel test, and simulation to understand the aerodynamic features of swept wings. The high-lift performance of the cranked-arrow wing planform is critical for recent and past supersonic transport design concepts. Simulations of the low speed high angle of attack Flight Condition 25 are compared: Detached Eddy Simulation (DES), Modi ed Delayed Detached Eddy Simulation (MDDES), and the Spalart-Allmaras (SA) RANS model. Iso- surfaces of Q criterion show the development of coherent primary and secondary vortices on the upper surface of the wing that spiral, burst, and commingle. SA produces higher pressure peaks nearer to the leading-edge of the wing than flight test measurements. Mean DES and MDDES pressures better predict the flight test measurements, especially on the outer wing section. Vorticies and vortex-vortex interaction impact unsteady surface pressures. USM3D showed many sharp tones in volume points spectra near the wing apex with low broadband noise and FUN3D showed more broadband noise with weaker tones. Spectra of the volume points near the outer wing leading-edge was primarily broadband for both codes. Without unsteady flight measurements, the flight pressure environment can not be used to validate the simulations containing tonal or broadband spectra. Mean forces and moment are very similar between FUN3D models and between USM3D models. Spectra of the unsteady forces and moment are broadband with a few sharp peaks for USM3D.

  11. One-equation sub-grid scale (SGS) modelling for Euler-Euler large eddy simulation (EELES) of dispersed bubbly flow

    NARCIS (Netherlands)

    Niceno, B.; Dhotre, M.T.; Deen, N.G.

    2008-01-01

    In this work, we have presented a one-equation model for sub-grid scale (SGS) kinetic energy and applied it for an Euler-Euler large eddy simulation (EELES) of a bubble column reactor. The one-equation model for SGS kinetic energy shows improved predictions over the state-of-the-art dynamic

  12. Benefits of a STEAM Collaboration in Newark, New Jersey: Volcano Simulation through a Glass-Making Experience

    Science.gov (United States)

    Gates, Alexander E.

    2017-01-01

    A simulated physical model of volcanic processes using a glass art studio greatly enhanced enthusiasm and learning among urban, middle- to high-school aged, largely underrepresented minority students in Newark, New Jersey. The collaboration of a geoscience department with a glass art studio to create a science, technology, engineering, arts, and…

  13. MODFLOW–USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation

    Science.gov (United States)

    Panday, Sorab; Langevin, Christian D.; Niswonger, Richard G.; Ibaraki, Motomu; Hughes, Joseph D.

    2013-01-01

    A new version of MODFLOW, called MODFLOW–USG (for UnStructured Grid), was developed to support a wide variety of structured and unstructured grid types, including nested grids and grids based on prismatic triangles, rectangles, hexagons, and other cell shapes. Flexibility in grid design can be used to focus resolution along rivers and around wells, for example, or to subdiscretize individual layers to better represent hydrostratigraphic units. MODFLOW–USG is based on an underlying control volume finite difference (CVFD) formulation in which a cell can be connected to an arbitrary number of adjacent cells. To improve accuracy of the CVFD formulation for irregular grid-cell geometries or nested grids, a generalized Ghost Node Correction (GNC) Package was developed, which uses interpolated heads in the flow calculation between adjacent connected cells. MODFLOW–USG includes a Groundwater Flow (GWF) Process, based on the GWF Process in MODFLOW–2005, as well as a new Connected Linear Network (CLN) Process to simulate the effects of multi-node wells, karst conduits, and tile drains, for example. The CLN Process is tightly coupled with the GWF Process in that the equations from both processes are formulated into one matrix equation and solved simultaneously. This robustness results from using an unstructured grid with unstructured matrix storage and solution schemes. MODFLOW–USG also contains an optional Newton-Raphson formulation, based on the formulation in MODFLOW–NWT, for improving solution convergence and avoiding problems with the drying and rewetting of cells. Because the existing MODFLOW solvers were developed for structured and symmetric matrices, they were replaced with a new Sparse Matrix Solver (SMS) Package developed specifically for MODFLOW–USG. The SMS Package provides several methods for resolving nonlinearities and multiple symmetric and asymmetric linear solution schemes to solve the matrix arising from the flow equations and the Newton

  14. A Simulation of Energy Storage System for Improving the Power System Stability with Grid-Connected PV using MCA Analysis and LabVIEW Tool

    Directory of Open Access Journals (Sweden)

    Jindrich Stuchly

    2015-01-01

    Full Text Available The large-scale penetration of distributed, Renewable power plants require transfers of large amounts of energy. This, in turn, puts a high strain on the energy delivery infrastructure. In particular, photovoltaic power plants supply energy with high intermittency, possibly affecting the stability of the grid by changing the voltage at the plant connection point. In this contribution, we summarize the main negative effects of selected and real-operated grid connected photovoltaic plant. Thereafter a review of suitable Energy storage systems to mitigate the negative effects has been carried out, compared and evaluated using Multi-criterion analysis. Based on this analysis, data collected at the plant and the grid, are used to design the energy storage systems to support connection of the plant to the grid. The cooperation of these systems is then analysed and evaluated using simulation tools created in LabVIEW for this purpose. The simulation results demonstrate the capability of energy storage system solutions to significantly reduce the negative feedback effects of Photovoltaic Power Plan to the low voltage grid.

  15. 单相光伏并网全系统仿真研究%Single-Phase Photovoltaic Grid-Connected Whole System Simulation Study

    Institute of Scientific and Technical Information of China (English)

    吴威; 张文菁; 张吉; 陈昆; 裴召刚

    2012-01-01

      Introduction was made to two-stage topologic structure of single-phase photovoltaic grid-connected generation system. Analysis was made to double-closed loop control for feed-forward grid voltage control. The system realized DC busbar voltage sta-bility and unit power factor grid-connected current. The system model was built based on Matlab simulation platform. Simulation result shows that BOOST circuit has realized max power point tracking technology better, DC busbar voltage keeps stability and grid-connected current and grid voltage keep on same frequency and phase.%  介绍了光伏并网发电系统的两级式拓扑结构,分析了引入电网电压前馈的双闭环控制策略,实现直流母线电压稳定以及单位功率因数并网电流。基于 Matlab 仿真平台,搭建了系统模型。仿真结果表明,BOOST 电路较好地实现了最大功率点跟踪技术,直流母线电压保持稳定,并网电流与电网电压保持同频同相

  16. Double-grid numerical methods for the numerical simulation of poly-phase flows in porous media; Methodes numeriques de double maillage pour la simulation numerique des ecoulements polyphasiques dans les milieux poreux

    Energy Technology Data Exchange (ETDEWEB)

    Verdiere, S.

    1997-04-29

    Petroleum reservoirs are made of highly heterogeneous rocks. Simulations of these reservoirs result in geo-scientific works to integrate the data and knowledge about the field. Generally, the reservoir is represented on a very high resolution (HR) grid which can be composed of millions of cells. In order to run fluid flow simulations, it is necessary to reduce the number of cells. Thus, conventional method is to coarsen the grid and to obtain a lower resolution (LR) grid by doing up-scaling before the fluid flow simulation is done. The alternative we propose to classical method is to consider, for a coupled system pressure-saturation a specific discretization in time and space for each unknown. So, for a two phase problem, the principle is to solve the pressure equation over a LR grid and the saturation equation over a HR grid. In addition to the usual steps used in an IMPES scheme, it is necessary to allow the transfer of the results of the implicit resolution of the pressure equation form the LR o the HR Grid and calculate the averaged parameters necessary to the resolution of the pressure equation during the next time step by taking into account the evolution of the saturation. The validation of the Dual Mesh Method has been done for a two-phase problem both theoretically and practically. (author) 73 refs.

  17. Wind Turbine Large-Eddy Simulations on Very Coarse Grid Resolutions using an Actuator Line Model

    CERN Document Server

    Tossas, Luis A Martínez; Meneveau, Charles

    2016-01-01

    In this work the accuracy of the Actuator Line Model (ALM) in Large Eddy Simulations of wind turbine flow is studied under the specific conditions of very coarse spatial resolutions. For finely-resolved conditions, it is known that ALM provides better accuracy compared to the standard Actuator Disk Model (ADM) without rotation. However, we show here that on very coarse resolutions, flow induction occurring at rotor scales can affect the predicted inflow angle and can adversely affect the ALM predictions. We first provide an illustration of coarse LES to reproduce wind tunnel measurements. The resulting flow predictions are good, but the challenges in predicting power outputs from the detailed ALM motivate more detailed analysis on a case with uniform inflow. We present a theoretical framework to compare the filtered quantities that enter the Large-Eddy Simulation equations as body forces with a scaling relation between the filtered and unfiltered quantities. The study aims to apply the theoretical derivation ...

  18. High-Reynolds Number Viscous Flow Simulations on Embedded-Boundary CartesianGrids

    Science.gov (United States)

    2016-05-05

    term goal of this research is to develop algorithms to simulate high Reynolds number turbulent flow in complicated geometries using embedded boundary...Spalding’s formula of matching the pro- files actually computed in the flow field by the Spalart-Allmaras turbulence model. In particular the profiles ...turbu- lent viscosity to be computed, see e.g. the profiles in the bottom row of Fig. 4. The streamwise velocity and especially the turbulent viscosity

  19. Production of BaBar Skimmed Analysis Datasets Using the Grid

    Energy Technology Data Exchange (ETDEWEB)

    Brew, C.A.J.; /Rutherford; Wilson, F.F.; /Rutherford; Castelli, G.; /Rutherford; Adye, T.; /Rutherford; Roethel, W.; /Rutherford; Luppi, E.; /INFN, Ferrara; Andreotti, D.; /INFN, Ferrara; Smith, D.; /SLAC; Khan, A.; /Brunel U.; Barrett, M.; /Brunel U.; Barlow, R.; /Manchester U.; Bailey, D.; /Manchester U.

    2011-11-10

    The BABAR Collaboration, based at Stanford Linear Accelerator Center (SLAC), Stanford, US, has been performing physics reconstruction, simulation studies and data analysis for 8 years using a number of compute farms around the world. Recent developments in Grid technologies could provide a way to manage the distributed resources in a single coherent structure. We describe enhancements to the BABAR experiment's distributed skimmed dataset production system to make use of European Grid resources and present the results with regard to BABAR's latest cycle of skimmed dataset production. We compare the benefits of a local and Grid-based systems, the ease with which the system is managed and the challenges of integrating the Grid with legacy software. We compare job success rates and manageability issues between Grid and non-Grid production.

  20. A Timed Colored Petri Net Simulation-Based Self-Adaptive Collaboration Method for Production-Logistics Systems

    Directory of Open Access Journals (Sweden)

    Zhengang Guo

    2017-03-01

    Full Text Available Complex and customized manufacturing requires a high level of collaboration between production and logistics in a flexible production system. With the widespread use of Internet of Things technology in manufacturing, a great amount of real-time and multi-source manufacturing data and logistics data is created, that can be used to perform production-logistics collaboration. To solve the aforementioned problems, this paper proposes a timed colored Petri net simulation-based self-adaptive collaboration method for Internet of Things-enabled production-logistics systems. The method combines the schedule of token sequences in the timed colored Petri net with real-time status of key production and logistics equipment. The key equipment is made ‘smart’ to actively publish or request logistics tasks. An integrated framework based on a cloud service platform is introduced to provide the basis for self-adaptive collaboration of production-logistics systems. A simulation experiment is conducted by using colored Petri nets (CPN Tools to validate the performance and applicability of the proposed method. Computational experiments demonstrate that the proposed method outperforms the event-driven method in terms of reductions of waiting time, makespan, and electricity consumption. This proposed method is also applicable to other manufacturing systems to implement production-logistics collaboration.

  1. A reduced switch count UPF power conditioner for grid connected variable speed wind energy conversion system employing PM generators: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Raju, A.B.; Fernandes, B.G.; Chatterjee, K. [Indian Institute of Technology, Mumbai (India). Dept. of Electrical Engineering

    2004-07-01

    In this paper, modelling and simulation of a grid connected variable speed wind energy conversion system (VSWECS) with reduced switch count power converter is presented. The system consists of a permanent magnet synchronous generator (PMSG), two-pulse width modulated B-4 power converters and a maximum power point tracker (MPPT). Mathematical models of each element of the system are developed separately and are then integrated to simulate the whole system for various wind velocities. The complete system is simulated using MATLAB/SIMULINK and simulation results are presented. (author)

  2. GRID Activities in ALICE

    Institute of Scientific and Technical Information of China (English)

    P.Cerello; T.Anticic; 等

    2001-01-01

    The challenge of LHC computing,with data rates in the range of several PB/year,requires the development of GRID technologies,to optimize the exploitation of distributed computing power and the authomatic access to distributed data storage.In the framework of the EU-DataGrid project,the ALICE experiment is one of the selected test applications for the early development and implementation of GRID Services.Presently,about 15 ALICE sites are makin use of available GRID tools and a large scale test production involving 9 of them was carried out with our simulation program.Results are discussed in detail,as well as future plans.

  3. Monte Carlo Simulations For The Cherenkov Telescope Array Observatory Using Pl-Grid E-Infrastructure

    Directory of Open Access Journals (Sweden)

    Anna Barnacka

    2012-01-01

    Full Text Available The paper presents Monte Carlo simulations carried out during the preparatory phase of the Cherenkov Telescope Array project. The aim of the project is to build the next generation observatory of very high energy gamma rays. During the preparatory phase there is a need to optimize and verify design concepts for various elements of the array. In this paper we describe the main components of the software being used for that purpose, their functions and requirements. Preliminary results of the optimization of the small telescope – one of the several kinds intended for the array, are presented.

  4. New iterative load balancing scheme with multi-grid level relaxation technique toward a large scale geodynamical granular simulation

    Science.gov (United States)

    Furuichi, M.; Nishiura, D.

    2016-12-01

    The complex dynamics of granular system is an essential part of natural processes such as crystal rich magma flow, accretion prism formation or tsunami sedimentation. Numerical modeling with Discrete Element Method (DEM) is an effective approach for understanding granular dynamics especially when the contact between particles induces strongly non-linear rheology (e.g. DEM-CFD simulation for magma reservoir [Bergantz et.al., Nature geo, 2015, Furuichi and Nishiura, G-cubed, 2014]). In Moving Lagrangian particle methods like DEM, a large number of particles is required to obtain an accurate solution. Therefore, an efficient parallelization of the code is important to handle huge particles system on HPC. However, since particles move around during the simulation, the workload between the different MPI processes becomes imbalance when using static sub-domains. To overcome this limitation, we present a new dynamic load balancing algorithms applicable to particle simulation methods such as DEM and Smoothed Particle Hydrodynamics (SPH) [Furuichi and Nishiura submitted to Comput. Phys. Comm.]. Our method utilizes flexible orthogonal domain decomposition in which the domain is divided into columns, each of which independently defines rectangle sub-domains by rows. We regard the difference of the executed time between neighbor logical processes as the residual of nonlinear problem of the domain change. The load balancing is attained by minimizing the residual within the framework of the iterative non-linear solver combined with the multi-grid level technique for the local relaxation. Scalability tests attest that the algorithm demonstrates close-to-optimal strong and weak scalability on the K-computer and the Earth Simulator. This result holds for even as well as uneven particle distribution, including different types of particles and heterogeneous computer architecture. We performed a DEM simulation with over 2 billion particles for demonstrating the proposed scheme. The

  5. An axis-free overset grid in spherical polar coordinates for simulating 3D self-gravitating flows

    CERN Document Server

    Wongwathanarat, Annop; Müller, Ewald

    2010-01-01

    A type of overlapping grid in spherical coordinates called the Yin-Yang grid is successfully implemented into a 3D version of the explicit Eulerian grid-based code PROMETHEUS including self-gravity. The modified code successfully passed several standard hydrodynamic tests producing results which are in very good agreement with analytic solutions. Moreover, the solutions obtained with the Yin-Yang grid exhibit no peculiar behaviour at the boundary between the two grid patches. The code has also been successfully used to model astrophysically relevant situations, namely equilibrium polytropes, a Taylor-Sedov explosion, and Rayleigh-Taylor instabilities. According to our results, the usage of the Yin-Yang grid greatly enhances the suitability and efficiency of 3D explicit Eulerian codes based on spherical polar coordinates for astrophysical flows.

  6. Simulation of 2D Kinetic Effects in Plasmas using the Grid Based Continuum Code LOKI

    Science.gov (United States)

    Banks, Jeffrey; Berger, Richard; Chapman, Tom; Brunner, Stephan

    2016-10-01

    Kinetic simulation of multi-dimensional plasma waves through direct discretization of the Vlasov equation is a useful tool to study many physical interactions and is particularly attractive for situations where minimal fluctuation levels are desired, for instance, when measuring growth rates of plasma wave instabilities. However, direct discretization of phase space can be computationally expensive, and as a result there are few examples of published results using Vlasov codes in more than a single configuration space dimension. In an effort to fill this gap we have developed the Eulerian-based kinetic code LOKI that evolves the Vlasov-Poisson system in 2+2-dimensional phase space. The code is designed to reduce the cost of phase-space computation by using fully 4th order accurate conservative finite differencing, while retaining excellent parallel scalability that efficiently uses large scale computing resources. In this poster I will discuss the algorithms used in the code as well as some aspects of their parallel implementation using MPI. I will also overview simulation results of basic plasma wave instabilities relevant to laser plasma interaction, which have been obtained using the code.

  7. Effects of High-Fidelity Simulation on Physical Therapy and Nursing Students' Attitudes Toward Interprofessional Learning and Collaboration.

    Science.gov (United States)

    Wellmon, Robert; Lefebvre, Kristin M; Ferry, Dawn

    2017-08-01

    The study purpose was to examine changes in physical therapy (PT) and nursing (RN) student attitudes toward interprofessional learning (IPL) and interprofessional collaboration (IPC) following a high-fidelity code simulation. PT (n = 42) and RN (n = 35) students, while working together to transfer a simulated patient, had to respond to a sudden and unexpected medical emergency. Pre- and postsurveys included the Interdisciplinary Education Perception Scale (IEPS), Readiness for Interprofessional Learning Scale (RIPLS), and Attitudes Toward Health Care Teams Scale (ATHCTS). A control group (PT, n = 41; RN, n = 33) of students were also surveyed. Statistically significant between- (p IEPS (competency and autonomy, perceived need for and perceptions of actual cooperation), the RIPLS (teamwork and collaboration, professional identity), and the ATHCTS (team value and efficiency). The IPL experience using high-fidelity simulation fostered the development of attitudes necessary for effective IPL and IPC. [J Nurs Educ. 2017;56(8):456-465.]. Copyright 2017, SLACK Incorporated.

  8. Power Flow Analysis of Island Business District 33KV Distribution Grid System with Real Network Simulations

    Directory of Open Access Journals (Sweden)

    Adesina, L.M

    2015-07-01

    Full Text Available The solution to power flow is one of the most important problems in electrical power systems. Traditional methods have been previously used for power flow analysis, but with prevalent drawbacks such as abnormal operating solutions and divergences in heavy loads. This paper presents power flow analysis in a power system, by modelling a typical 33kV Distribution Network, and simulating using the NEPLAN software for power flow studies. Island Business Unit’s (IBU 33kV network of Eko Electricity Distribution Plc (EKEDP for a scenario day is taken as case study in the analysis. The most important parameters of power flow analysis is utilized to find the magnitude and phase angles of the voltages at each Busbar, as well as the real and reactive power flowing through each distribution line within the network under consideration.

  9. Dynamic simulation of dispersed, grid-connected photovoltaic power systems: System studies

    Science.gov (United States)

    Wasynczuk, O.; Carroll, D. P.; Gareis, G. E.; Krause, P. C.; Ong, C. M.; Schwartz, R. J.

    1985-03-01

    To investigate the operating characteristics and dynamic behavior of photovoltaic (PV) power systems, four PV system configurations were selected as representative of those currently being used in PV applications. These included single and three phase, line and self commutated power conditioners with a flat plate PV array as the dc source. Detailed computer models of each of these systems were developed and incorporated into dynamic representations of typical primary and secondary distribution feeders. The dynamic electrical behavior of the PV and distribution systems following common network disturbances such as large load changes, PV system startup, and cloud cover transients are characterized. The dynamic behavior was also investigated during abnormal operating conditions following line faults, PV system malfunctions, and islanding or distribution systems containing significant levels of dispersed PV generation. Results of verification tests involving two of the single phase PV system configurations, in which the simulated response characteristics are compared with actual measurements, are also provided.

  10. An Investigation of Wavelet Bases for Grid-Based Multi-Scale Simulations Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Baty, R.S.; Burns, S.P.; Christon, M.A.; Roach, D.W.; Trucano, T.G.; Voth, T.E.; Weatherby, J.R.; Womble, D.E.

    1998-11-01

    The research summarized in this report is the result of a two-year effort that has focused on evaluating the viability of wavelet bases for the solution of partial differential equations. The primary objective for this work has been to establish a foundation for hierarchical/wavelet simulation methods based upon numerical performance, computational efficiency, and the ability to exploit the hierarchical adaptive nature of wavelets. This work has demonstrated that hierarchical bases can be effective for problems with a dominant elliptic character. However, the strict enforcement of orthogonality was found to be less desirable than weaker semi-orthogonality or bi-orthogonality for solving partial differential equations. This conclusion has led to the development of a multi-scale linear finite element based on a hierarchical change of basis. The reproducing kernel particle method has been found to yield extremely accurate phase characteristics for hyperbolic problems while providing a convenient framework for multi-scale analyses.

  11. Controlling smart grid adaptivity

    NARCIS (Netherlands)

    Toersche, Hermen; Nykamp, Stefan; Molderink, Albert; Hurink, Johann L.; Smit, Gerardus Johannes Maria

    2012-01-01

    Methods are discussed for planning oriented smart grid control to cope with scenarios with limited predictability, supporting an increasing penetration of stochastic renewable resources. The performance of these methods is evaluated with simulations using measured wind generation and consumption

  12. Using gridded rainfall products in simulating streamflow in a tropical catchment – A case study of the Srepok River Catchment, Vietnam

    Directory of Open Access Journals (Sweden)

    Thom Vu Thi

    2017-03-01

    Full Text Available The precise rainfall estimate with appropriate spatial and temporal resolutions is a key input to distributed hydrological models. However, networks of rain gauges are often sparsely distributed in developing countries. To overcome such limitations, this study used some of the existing gridded rainfall products to simulate streamflow. Four gridded rainfall products, including APHRODITE, CFSR, PERSIANN, and TRMM, were used as input to the SWAT distributed hydrological model in order to simulate streamflow over the Srepok River Catchment in Vietnam. Besides that, the available rain gauges data were also used for comparison. Amongst the four different datasets, the TRMM and APHRODITE data show their best match to rain gauges data in simulating the daily and monthly streamflow with satisfactory precision in the 2000-2006 period. The result indicates that the TRMM and APHRODITE data have potential applications in driving hydrological model and water resources management in data-scarce and ungauged areas in Vietnam.

  13. MESA and NuGrid Simulations of Classical Nova Outbursts: ONe Nova and Nucleosynthesis

    CERN Document Server

    Denissenkov, Pavel A; Pignatari, Marco; Trappitsch, Reto; Ritter, Christian; Herwig, Falk; Battino, Umberto; Setoodehnia, Kiana

    2013-01-01

    Classical novae are the result of thermonuclear flashes of H accreted by CO or ONe white dwarfs, leading eventually to the dynamic ejection of the surface layers. These are observationally known to be enriched in heavy elements, such as C, O and Ne that must originate in layers below the H-flash convection zone. Building on our previous work we now present stellar evolution simulations of ONe nova, and provide a comprehensive comparison of our models with previous work. Some of our models include exponential convective boundary mixing model to account for the observed enrichment of the ejecta even when accreting material with a solar abundance distribution. Our models produce maximum temperature evolution profiles and nucleosynthesis yields in good agreement with models that generate enriched ejecta by assuming that the accreted material was pre-enriched. We confirm for ONe nova the result we reported previously, i.e. we found that 3He can be produced in situ in solar-composition envelopes accreted with slow ...

  14. Sub-grid scale combustion models for large eddy simulation of unsteady premixed flame propagation around obstacles.

    Science.gov (United States)

    Di Sarli, Valeria; Di Benedetto, Almerinda; Russo, Gennaro

    2010-08-15

    In this work, an assessment of different sub-grid scale (sgs) combustion models proposed for large eddy simulation (LES) of steady turbulent premixed combustion (Colin et al., Phys. Fluids 12 (2000) 1843-1863; Flohr and Pitsch, Proc. CTR Summer Program, 2000, pp. 61-82; Kim and Menon, Combust. Sci. Technol. 160 (2000) 119-150; Charlette et al., Combust. Flame 131 (2002) 159-180; Pitsch and Duchamp de Lageneste, Proc. Combust. Inst. 29 (2002) 2001-2008) was performed to identify the model that best predicts unsteady flame propagation in gas explosions. Numerical results were compared to the experimental data by Patel et al. (Proc. Combust. Inst. 29 (2002) 1849-1854) for premixed deflagrating flame in a vented chamber in the presence of three sequential obstacles. It is found that all sgs combustion models are able to reproduce qualitatively the experiment in terms of step of flame acceleration and deceleration around each obstacle, and shape of the propagating flame. Without adjusting any constants and parameters, the sgs model by Charlette et al. also provides satisfactory quantitative predictions for flame speed and pressure peak. Conversely, the sgs combustion models other than Charlette et al. give correct predictions only after an ad hoc tuning of constants and parameters.

  15. 基于网格的蠕虫行为模拟器%INTERNET WORM BEHAVIOR SIMULATOR BASED ON GRID

    Institute of Scientific and Technical Information of China (English)

    庄新妍; 刘扬; 董改芳

    2014-01-01

    传统的网络模拟器对Internt蠕虫行为模拟存在性能与功能上的局限性,因此设计了基于网格的Internet蠕虫行为模拟器(Grid Based Internct Worm Behavior Simulator,GBIWBS网格).IWBS网格利用实际网络拓扑信息、链路信息和路由信忠实现数据报文级的蠕虫行为模拟;利用网格的计算能力、资源管理、任务管理等优势,实现了一种新的Internet蠕虫行为模拟器.结果表明IWBS网格不仅在模拟规模上远远超过已有的模拟器,而且其提供的跟踪蠕虫传播轨迹的功能为蠕虫的进一步研究提供了宝贵的数据;同时,它也是实践和应用网格技术的示范,能够促进网格技术的进一步的研究与发展.

  16. Numerical Simulation of Rotor Flow Field Based on Overset Grids and Several Spatial and Temporal Discretization Schemes

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming; CAO Yihua

    2012-01-01

    A numerical method based on solutions of Euler/Navier-Stokes (N-S) equations is developed for calculating the flow field over a rotor in hover.Jameson central scheme,van Leer flux-vector splitting scheme,advection upwind splitting method (AUSM) scheme,upwind AUSM/van Leer scheme,AUSM+ scheme and AUSMDV scheme are implemented for spatial discretization,and van Albada limiter is also applied.For temporal discretization,both explicit Runge-Kutta method and implicit lower-upper symmetric Gauss-Seidel (LU-SGS) method are attempted.Simultaneously,overset grid technique is adopted.In detail,hole-map method is utilized to identify intergrid boundary points (IGBPs).Furthermore,aimed at identification issue of donor elements,inverse-map method is implemented.Eventually,blade surface pressure distributions derived from numerical simulation are validated compared with experimental data,showing that all the schemes mentioned above have the capability to predict the rotor flow field accurately.At the same time,vorticity contours are illustrated for analysis,and other characteristics are also analyzed.

  17. Particle Simulations of a Thermionic RF Gun with Gridded Triode Structure for Reduction of Back-Bombardment

    CERN Document Server

    Kusukame, K; Kii, T; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    Thermionic RF guns show advantageous features compared with photocathode ones such as easy operation and much higher repetition rate of micropulses, both of which are suitable for their application to high average power FELs. They however suffer from the back-bombardment effect [1], i.e., in conventional RF guns, electrons are extracted from cathode also in the latter half of accelerating phase and tend to back-stream to hit the cathode, and as a result the macropulse duration is limited down to severalμsec Against this adverse effect in thermionic RF guns, introduction of the triode structure has been proposed [2], where the accelerating phase and amplitude nearby the cathode can be controlled regardless of the phase of the first accelerating cell in the conventional RF gun. Our one-dimensional particle simulation results predict that the back-bombardment power can be reduced by 99 % only with 30-40 kW RF power fed to the grid in the present triode structure with an optimal phase difference from th...

  18. Thermal Protection System Cavity Heating for Simplified and Actual Geometries Using Computational Fluid Dynamics Simulations with Unstructured Grids

    Science.gov (United States)

    McCloud, Peter L.

    2010-01-01

    Thermal Protection System (TPS) Cavity Heating is predicted using Computational Fluid Dynamics (CFD) on unstructured grids for both simplified cavities and actual cavity geometries. Validation was performed using comparisons to wind tunnel experimental results and CFD predictions using structured grids. Full-scale predictions were made for simplified and actual geometry configurations on the Space Shuttle Orbiter in a mission support timeframe.

  19. Numerical Simulation Of The Treatment Of Soil Swelling Using Grid Geocell Columns

    Directory of Open Access Journals (Sweden)

    Fattah Mohammed Y.

    2015-06-01

    Full Text Available In this paper, a method for the treatment of the swelling of expansive soil is numerically simulated. The method is simply based on the embedment of a geogrid (or a geomesh in the soil. The geogrid is extended continuously inside the volume of the soil where the swell is needed to be controlled and orientated towards the direction of the swell. Soils with different swelling potentials are employed: bentonite base-Na and bentonite base-Ca samples in addition to kaolinite mixed with bentonite. A numerical analysis was carried out by the finite element method to study the swelling soil's behavior and investigate the distribution of the stresses and pore water pressures around the geocells beneath the shallow footings. The ABAQUS computer program was used as a finite element tool, and the soil is represented by the modified Drucker-Prager/cap model. The geogrid surrounding the geocell is assumed to be a linear elastic material throughout the analysis. The soil properties used in the modeling were experimentally obtained. It is concluded that the degree of saturation and the matric suction (the negative pore water pressure decrease as the angle of friction of the geocell column material increases due to the activity of the sand fill in the dissipation of the pore water pressure and the acceleration of the drainage through its function as a drain. When the plasticity index and the active depth (the active zone is considered to be equal to the overall depth of the clay model increase, the axial movement (swelling movement and matric suction, as a result of the increase in the axial forces, vary between this maximum value at the top of the layer and the minimum value in the last third of the active depth and then return to a consolidation at the end of the depth layer.

  20. When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study.

    Science.gov (United States)

    Haidari, Leila A; Brown, Shawn T; Wedlock, Patrick; Connor, Diana L; Spiker, Marie; Lee, Bruce Y

    2017-04-19

    Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as "electric refrigerators") at different locations in the supply chain under various circumstances. At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar refrigerator prices. Copyright © 2017. Published

  1. When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study☆

    Science.gov (United States)

    Haidari, Leila A.; Brown, Shawn T.; Wedlock, Patrick; Connor, Diana L.; Spiker, Marie; Lee, Bruce Y.

    2017-01-01

    Background Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent? Methods Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as “electric refrigerators”) at different locations in the supply chain under various circumstances. Results At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities. Conclusion Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar

  2. Collaborative Modelling and Co-Simulation with DESTECS: A Pilot Study

    NARCIS (Netherlands)

    Pierce, Ken; Gamble, Garl; Ni, Yunyun; Broenink, Johannes F.

    2012-01-01

    This paper describes a collaborative modelling ex- ercise using the DESTECS framework. The DESTECS approach allows engineers and software designers to collaborate to produce system models that contain a discrete-event (DE) model of a controller and continuous-time (CT) model of a plant. We call

  3. Investigating the Effects of Grid Resolution of WRF Model for Simulating the Atmosphere for use in the Study of Wake Turbulence

    Science.gov (United States)

    Prince, Alyssa; Trout, Joseph; di Mercurio, Alexis

    2017-01-01

    The Weather Research and Forecasting (WRF) Model is a nested-grid, mesoscale numerical weather prediction system maintained by the Developmental Testbed Center. The model simulates the atmosphere by integrating partial differential equations, which use the conservation of horizontal momentum, conservation of thermal energy, and conservation of mass along with the ideal gas law. This research investigated the possible use of WRF in investigating the effects of weather on wing tip wake turbulence. This poster shows the results of an investigation into the accuracy of WRF using different grid resolutions. Several atmospheric conditions were modeled using different grid resolutions. In general, the higher the grid resolution, the better the simulation, but the longer the model run time. This research was supported by Dr. Manuel A. Rios, Ph.D. (FAA) and the grant ``A Pilot Project to Investigate Wake Vortex Patterns and Weather Patterns at the Atlantic City Airport by the Richard Stockton College of NJ and the FAA'' (13-G-006). Dr. Manuel A. Rios, Ph.D. (FAA), and the grant ``A Pilot Project to Investigate Wake Vortex Patterns and Weather Patterns at the Atlantic City Airport by the Richard Stockton College of NJ and the FAA''

  4. Stable, high-order SBP-SAT finite difference operators to enable accurate simulation of compressible turbulent flows on curvilinear grids, with application to predicting turbulent jet noise

    Science.gov (United States)

    Byun, Jaeseung; Bodony, Daniel; Pantano, Carlos

    2014-11-01

    Improved order-of-accuracy discretizations often require careful consideration of their numerical stability. We report on new high-order finite difference schemes using Summation-By-Parts (SBP) operators along with the Simultaneous-Approximation-Terms (SAT) boundary condition treatment for first and second-order spatial derivatives with variable coefficients. In particular, we present a highly accurate operator for SBP-SAT-based approximations of second-order derivatives with variable coefficients for Dirichlet and Neumann boundary conditions. These terms are responsible for approximating the physical dissipation of kinetic and thermal energy in a simulation, and contain grid metrics when the grid is curvilinear. Analysis using the Laplace transform method shows that strong stability is ensured with Dirichlet boundary conditions while weaker stability is obtained for Neumann boundary conditions. Furthermore, the benefits of the scheme is shown in the direct numerical simulation (DNS) of a Mach 1.5 compressible turbulent supersonic jet using curvilinear grids and skew-symmetric discretization. Particularly, we show that the improved methods allow minimization of the numerical filter often employed in these simulations and we discuss the qualities of the simulation.

  5. Slat Noise Predictions Using Higher-Order Finite-Difference Methods on Overset Grids

    Science.gov (United States)

    Housman, Jeffrey A.; Kiris, Cetin

    2016-01-01

    Computational aeroacoustic simulations using the structured overset grid approach and higher-order finite difference methods within the Launch Ascent and Vehicle Aerodynamics (LAVA) solver framework are presented for slat noise predictions. The simulations are part of a collaborative study comparing noise generation mechanisms between a conventional slat and a Krueger leading edge flap. Simulation results are compared with experimental data acquired during an aeroacoustic test in the NASA Langley Quiet Flow Facility. Details of the structured overset grid, numerical discretization, and turbulence model are provided.

  6. Neutron Science TeraGrid Gateway

    Science.gov (United States)

    Lynch, Vickie; Chen, Meili; Cobb, John; Kohl, Jim; Miller, Steve; Speirs, David; Vazhkudai, Sudharshan

    2010-11-01

    The unique contributions of the Neutron Science TeraGrid Gateway (NSTG) are the connection of national user facility instrument data sources to the integrated cyberinfrastructure of the National Science FoundationTeraGrid and the development of a neutron science gateway that allows neutron scientists to use TeraGrid resources to analyze their data, including comparison of experiment with simulation. The NSTG is working in close collaboration with the Spallation Neutron Source (SNS) at Oak Ridge as their principal facility partner. The SNS is a next-generation neutron source. It has completed construction at a cost of 1.4 billion and is ramping up operations. The SNS will provide an order of magnitude greater flux than any previous facility in the world and will be available to all of the nation's scientists, independent of funding source, on a peer-reviewed merit basis. With this new capability, the neutron science community is facing orders of magnitude larger data sets and is at a critical point for data analysis and simulation. There is a recognized need for new ways to manage and analyze data to optimize both beam time and scientific output. The TeraGrid is providing new capabilities in the gateway for simulations using McStas and a fitting service on distributed TeraGrid resources to improved turnaround. NSTG staff are also exploring replicating experimental data in archival storage. As part of the SNS partnership, the NSTG provides access to gateway support, cyberinfrastructure outreach, community development, and user support for the neutron science community. This community includes not only SNS staff and users but extends to all the major worldwide neutron scattering centers.

  7. Neutron Science TeraGrid Gateway

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Vickie E [ORNL; Chen, Meili [ORNL; Cobb, John W [ORNL; Kohl, James Arthur [ORNL; Miller, Stephen D [ORNL; Speirs, David A [ORNL; Vazhkudai, Sudharshan S [ORNL

    2010-01-01

    The unique contributions of the Neutron Science TeraGrid Gateway (NSTG) are the connection of national user facility instrument data sources to the integrated cyberinfrastructure of the National Science FoundationTeraGrid and the development of a neutron science gateway that allows neutron scientists to use TeraGrid resources to analyze their data, including comparison of experiment with simulation. The NSTG is working in close collaboration with the Spallation Neutron Source (SNS) at Oak Ridge as their principal facility partner. The SNS is a next-generation neutron source. It has completed construction at a cost of $1.4 billion and is ramping up operations. The SNS will provide an order of magnitude greater flux than any previous facility in the world and will be available to all of the nation's scientists, independent of funding source, on a peer-reviewed merit basis. With this new capability, the neutron science community is facing orders of magnitude larger data sets and is at a critical point for data analysis and simulation. There is a recognized need for new ways to manage and analyze data to optimize both beam time and scientific output. The TeraGrid is providing new capabilities in the gateway for simulations using McStas and a fitting service on distributed TeraGrid resources to improved turnaround. NSTG staff are also exploring replicating experimental data in archival storage. As part of the SNS partnership, the NSTG provides access to gateway support, cyberinfrastructure outreach, community development, and user support for the neutron science community. This community includes not only SNS staff and users but extends to all the major worldwide neutron scattering centers.

  8. Neutron Science TeraGrid Gateway

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Vickie; Chen Meili; Cobb, John; Kohl, Jim; Miller, Steve; Speirs, David; Vazhkudai, Sudharshan, E-mail: lynchve@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2010-11-01

    The unique contributions of the Neutron Science TeraGrid Gateway (NSTG) are the connection of national user facility instrument data sources to the integrated cyberinfrastructure of the National Science FoundationTeraGrid and the development of a neutron science gateway that allows neutron scientists to use TeraGrid resources to analyze their data, including comparison of experiment with simulation. The NSTG is working in close collaboration with the Spallation Neutron Source (SNS) at Oak Ridge as their principal facility partner. The SNS is a next-generation neutron source. It has completed construction at a cost of $1.4 billion and is ramping up operations. The SNS will provide an order of magnitude greater flux than any previous facility in the world and will be available to all of the nation's scientists, independent of funding source, on a peer-reviewed merit basis. With this new capability, the neutron science community is facing orders of magnitude larger data sets and is at a critical point for data analysis and simulation. There is a recognized need for new ways to manage and analyze data to optimize both beam time and scientific output. The TeraGrid is providing new capabilities in the gateway for simulations using McStas and a fitting service on distributed TeraGrid resources to improved turnaround. NSTG staff are also exploring replicating experimental data in archival storage. As part of the SNS partnership, the NSTG provides access to gateway support, cyberinfrastructure outreach, community development, and user support for the neutron science community. This community includes not only SNS staff and users but extends to all the major worldwide neutron scattering centers.

  9. 西北电网数字仿真实验室的建设%Construction of the Simulation Laboratory in Northwest China Grid

    Institute of Scientific and Technical Information of China (English)

    李刚; 张星; 林卫星; 孙海顺; 尚勇; 施荣

    2012-01-01

    A digital simulation laboratory of sending-end power grid with multi-type power sources was constructed by Northwest China Grid Company in 2009 to enhance its capability of power grid simulation and to deal with the grave technical issues including large-scale wind power integration,high-capacity DC multiple-point sending,FACTS technology application and very large-scale synchronous power gird stability.This paper introduces the configurations,functions,and main performance index of the laboratory as well as some of the major simulation works based on the laboratory.Finally,the development prospect of laboratory is discussed.%为提升电网仿真计算能力,解决大型风电并网、大容量直流多点外送、柔性交流输电技术应用及超大规模同步电网稳定等重大技术问题,西北电网公司于2009年建成"多类电源送端电网数字仿真实验室"。介绍了实验室的配置、功能、主要性能指标以及基于该实验室的若干重大仿真试验研究工作。最后展望了实验室的发展前景。

  10. Efficient design and simulation of an expandable hybrid (wind-photovoltaic) power system with MPPT and inverter input voltage regulation features in compliance with electric grid requirements

    Energy Technology Data Exchange (ETDEWEB)

    Skretas, Sotirios B.; Papadopoulos, Demetrios P. [Electrical Machines Laboratory, Department of Electrical and Computer Engineering, Democritos University of Thrace (DUTH), 12 V. Sofias, 67100 Xanthi (Greece)

    2009-09-15

    In this paper an efficient design along with modeling and simulation of a transformer-less small-scale centralized DC - bus Grid Connected Hybrid (Wind-PV) power system for supplying electric power to a single phase of a three phase low voltage (LV) strong distribution grid are proposed and presented. The main components of the hybrid system are: a PV generator (PVG); and an array of horizontal-axis, fixed-pitch, small-size, variable-speed wind turbines (WTs) with direct-driven permanent magnet synchronous generator (PMSG) having an embedded uncontrolled bridge rectifier. An overview of the basic theory of such systems along with their modeling and simulation via Simulink/MATLAB software package are presented. An intelligent control method is applied to the proposed configuration to simultaneously achieve three desired goals: to extract maximum power from each hybrid power system component (PVG and WTs); to guarantee DC voltage regulation/stabilization at the input of the inverter; to transfer the total produced electric power to the electric grid, while fulfilling all necessary interconnection requirements. Finally, a practical case study is conducted for the purpose of fully evaluating a possible installation in a city site of Xanthi/Greece, and the practical results of the simulations are presented. (author)

  11. Grid Computing

    Indian Academy of Sciences (India)

    2016-05-01

    A computing grid interconnects resources such as high performancecomputers, scientific databases, and computercontrolledscientific instruments of cooperating organizationseach of which is autonomous. It precedes and is quitedifferent from cloud computing, which provides computingresources by vendors to customers on demand. In this article,we describe the grid computing model and enumerate themajor differences between grid and cloud computing.

  12. A Probabilistic Method for Determining Grid-Accommodable Wind Power Capacity Based on Multiscenario System Operation Simulation

    DEFF Research Database (Denmark)

    Xu, Qianyao; Kang, Chongqing; Zhang, Ning

    2016-01-01

    When conducting the wind power (WP) planning, it is very important for electric power companies to evaluate the penetration limit of the grid-accommodable WP. This paper proposes a probabilistic method for determining grid-accommodable WP capacity based on the multiscenario analysis. Typical power....... The validity and effectiveness of the new method are demonstrated in two cases, i.e., the IEEE 39-bus test system and a real large power system in China, respectively....

  13. Dynamic Modeling, Control and Simulation of a Wind and PV Hybrid System for Grid Connected Application Using MATLAB

    OpenAIRE

    2014-01-01

    This paper proposes a dynamic modeling and control strategy for a grid connected hybrid wind and photovoltaic (PV) energy system inter-connected to electrical grid through power electronic interface. A gearless permanent magnet synchronous generator (PMSG) is used to capture the maximum wind energy. The PV and wind systems are connected dc-side of the voltage source inverter through a boost converter individually and maintain a fixed dc output at dc link. A proper control sche...

  14. Three-Dimensional Simulation of SOFC Anode Polarization Characteristics Based on Sub-Grid Scale Modeling of Microstructure

    OpenAIRE

    2012-01-01

    Three-dimensional numerical analysis of solid oxide fuel cell (SOFC) anode polarization is conducted with a microstructure obtained by a focused ion beam and scanning electron microscope (FIB-SEM). Electronic, ionic and gaseous transports with electrochemical reaction are considered in the porous anode. A sub-grid scale (SGS) model is newly developed and effectively used to consider the structural information whose characteristic scale is smaller than calculation grid size. The proposed SGS m...

  15. GRID super scalar: from the Grid to the Cell processor

    Energy Technology Data Exchange (ETDEWEB)

    Badia, R. M.; Bellerns, P.; Palol, M. de; Ejarque, J.; Labarta, J.; Perez, J. M.; Sirvent, R.; Tejedor, E.

    2007-07-01

    GRID superscalar is a Grid programming environment that allows to easily program applications that will be efficiently run on a computational Grid. Is able to parallelise, at runtime and at task level, a sequential application and execute it in the Grid. The used approach is able to take benefit from those applications that are composed of coarse grained tasks. These tasks can be the size of a simulation, a program, a solver... These kinds of applications are very common in bioinformatics, computational chemistry and other scientific fields. From the very initial prototype in Condor, GRID superscalar has evolved in a robust framework based in Globus and other middlewares. The effort of the GRID superscalar project goes beyond the Grid computing field, tackling now the newest field of programming multi-core chip's platforms. This paper describes the currently available versions of GRID superscalar. (Author)

  16. Nbody Simulations and Weak Gravitational Lensing using new HPC-Grid resources: the PI2S2 project

    Science.gov (United States)

    Becciani, U.; Antonuccio-Delogu, V.; Costa, A.; Comparato, M.

    2008-08-01

    We present the main project of the new grid infrastructure and the researches, that have been already started in Sicily and will be completed by next year. The PI2S2 project of the COMETA consortium is funded by the Italian Ministry of University and Research and will be completed in 2009. Funds are from the European Union Structural Funds for Objective 1 regions. The project, together with a similar project called Trinacria GRID Virtual Laboratory (Trigrid VL), aims to create in Sicily a computational grid for e-science and e-commerce applications with the main goal of increasing the technological innovation of local enterprises and their competition on the global market. PI2S2 project aims to build and develop an e-Infrastructure in Sicily, based on the grid paradigm, mainly for research activity using the grid environment and High Performance Computer systems. As an example we present the first results of a new grid version of FLY a tree Nbody code developed by INAF Astrophysical Observatory of Catania, already published in the CPC program Library, that will be used in the Weak Gravitational Lensing field.

  17. Workshop on Future Generation Grids

    CERN Document Server

    Laforenza, Domenico; Reinefeld, Alexander

    2006-01-01

    The Internet and the Web continue to have a major impact on society. By allowing us to discover and access information on a global scale, they have created entirely new businesses and brought new meaning to the term surf. In addition, however, we want processing, and increasingly, we want collaborative processing within distributed teams. This need has led to the creation of the Grid - an infrastructure that enables us to share capabilities, and integrate services and resources within and across enterprises. "Future Generation Grids" is the second in the "CoreGRID" series. This edited volume brings together contributed articles by scientists and researchers in the Grid community in an attempt to draw a clearer picture of the future generation Grids. This book also identifies some of the most challenging problems on the way to achieving the invisible Grid ideas

  18. An electrostatic analog for generating cascade grids

    Science.gov (United States)

    Adamczyk, J. J.

    1980-01-01

    Accurate and efficient numerical simulation of flows through turbomachinery blade rows depends on the topology of the computational grids. These grids must reflect the periodic nature of turbomachinery blade row geometries and conform to the blade shapes. Three types of grids can be generated that meet these minimal requirements: through-flow grids, O-type grids, and C-type grids. A procedure which can be used to generate all three types of grids is presented. The resulting grids are orthogonal and can be stretched to capture the essential physics of the flow. A discussion is also presented detailing the extension of the generation procedure to three dimensional geometries.

  19. VINCASim:A Simulation Toolkit for Evaluating Dependability of Grid Workflows%VINCASim:一种网格工作流可靠性仿真工具

    Institute of Scientific and Technical Information of China (English)

    赵小伟; 张利永; 韩燕波

    2009-01-01

    网格工作流作为综合利用网格资源求解问题的"编程"技术已得到广泛应用,其可靠性保障研究得到越来越多的关注.然而,面对网格环境固有的复杂性和不确定性,如何时可靠性保障方法有效、方便地进行评测,是一个有待深入探索的挑战性问题.以VINCA网格工作流为参考原型,对影响其可靠性的因素进行了系统的分析,抽象出了网格工作流系统组件模型和可靠性属性模型,并基于GridSim实现了一个可配置、易扩展的网格工作流可靠性仿真工具包--VINCASim.此工具可以通过配置方便地模拟节点失效、工作流引擎失效、网络连接失效、流程执行异常等出错情形,提供扩展接口支持以编程的方式引入各种可靠性保障方法,为评测不同方法的有效性提供可控的、可重复的实验平台.通过场景示例说明了该工具的扩展性和易用性.%As a special kind of "programming" technology for constructing problem-solving applications on the basis of grid resources,grid workflow has been widely applied.Methodologies for ensuring ddependability of grid workflows have attracted attention.However, it remains a challenge how to evaluate the effectiveness of these methodologies due to the complexity and uncertainty of grid environments.Based on VINCA grid workflow, key factors that affect the depen dability were systematically analyzed, and a general component model and dependability attributes model for grid work-flow systems were established.A configurable and extensible simulation toolkit called VINCASim for evaluating the de-pendability of grid workflows was developed based on GridSirn.The toolkit can simulate various failures raised from grid nodes, workflow engines, network connection and workflow execution in a configurable manner, and supports incor-porating different dependability ensuring methods programmatically.Thus, a controllable and repeatable experiment platform was provided for

  20. Cloud Computing for the Grid: GridControl: A Software Platform to Support the Smart Grid

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-02-08

    GENI Project: Cornell University is creating a new software platform for grid operators called GridControl that will utilize cloud computing to more efficiently control the grid. In a cloud computing system, there are minimal hardware and software demands on users. The user can tap into a network of computers that is housed elsewhere (the cloud) and the network runs computer applications for the user. The user only needs interface software to access all of the cloud’s data resources, which can be as simple as a web browser. Cloud computing can reduce costs, facilitate innovation through sharing, empower users, and improve the overall reliability of a dispersed system. Cornell’s GridControl will focus on 4 elements: delivering the state of the grid to users quickly and reliably; building networked, scalable grid-control software; tailoring services to emerging smart grid uses; and simulating smart grid behavior under various conditions.

  1. 75 FR 66752 - Smart Grid Interoperability Standards; Notice of Technical Conference

    Science.gov (United States)

    2010-10-29

    ... Energy Regulatory Commission Smart Grid Interoperability Standards; Notice of Technical Conference... regulatory authorities that also are considering the adoption of Smart Grid Interoperability Standards.../FERC Collaborative on Smart Response (Collaborative), in the International D Ballroom at the Omni Hotel...

  2. Simulation of dynamic processes in three-dimensional layered fractured media with the use of the grid-characteristic numerical method

    Science.gov (United States)

    Golubev, V. I.; Gilyazutdinov, R. I.; Petrov, I. B.; Khokhlov, N. I.; Vasyukov, A. V.

    2017-05-01

    This paper touches upon the computer simulation of the propagation of elastic waves in three-dimensional multilayer fractured media. The dynamic processes are described using the defining system of equations in the partial derivatives of the deformed solid mechanics. The numerical solution of this system is carried out via the grid-characteristic method on curvilinear structural grids. The fractured nature of the medium is accounted for by explicitly selecting the boundaries of individual cracks and setting special boundary conditions in them. Various models of heterogeneous deformed media with a fractured structures are considered: a homogeneous medium, a medium with horizontal boundaries, a medium with inclined boundaries, and a medium curvilinear boundaries. The wave fields detected on the surface are obtained, and their structures are analyzed. It is demonstrated that it is possible to detect the waves scattered from fractured media even in the case of nonparallel (inclined and curvilinear) boundaries of geological layers.

  3. 基于风-网互补供电试验的风力机模拟研究%Wind Turbine Simulation Research based on the Test of Off-grid Wind Power-Grid Power Complementary Power Supply System

    Institute of Scientific and Technical Information of China (English)

    唐志诚; 叶会华

    2013-01-01

      以抽油机离网风电-网电互补供电试验系统中的风力机为研究对象,根据风力机的运行特性,运用相似理论得到了模型试验中与风力机相似应满足的条件。计算了与某实际风力机在对应工况下相似的模型风力机的相关参数。在此基础上,建立一个由变频器拖动电机组成的试验模型来模拟风力机的运行,保证了试验模型具有实际意义。%Wind turbines used in the off-grid wind power-grid power complementary power supply system for pumping unit were selected as the research object. According to the operating characteristics of wind turbines, the pre-conditions of wind turbines similarity in the model test were obtained by using similarity theory. The parameters of the model wind turbine were calculated under the condition which was corresponding to a real wind turbine. On this basis, a test model composed of in-verter-driven motor for the simulation of wind turbine was established to guarantee that the test model was feasible and effec-tive.

  4. An unstaggered central scheme on nonuniform grids for the simulation of a compressible two-phase flow model

    Energy Technology Data Exchange (ETDEWEB)

    Touma, Rony [Department of Computer Science & Mathematics, Lebanese American University, Beirut (Lebanon); Zeidan, Dia [School of Basic Sciences and Humanities, German Jordanian University, Amman (Jordan)

    2016-06-08

    In this paper we extend a central finite volume method on nonuniform grids to the case of drift-flux two-phase flow problems. The numerical base scheme is an unstaggered, non oscillatory, second-order accurate finite volume scheme that evolves a piecewise linear numerical solution on a single grid and uses dual cells intermediately while updating the numerical solution to avoid the resolution of the Riemann problems arising at the cell interfaces. We then apply the numerical scheme and solve a classical drift-flux problem. The obtained results are in good agreement with corresponding ones appearing in the recent literature, thus confirming the potential of the proposed scheme.

  5. Development of web-based collaborative framework for the simulation of embedded systems

    Directory of Open Access Journals (Sweden)

    Woong Yang

    2016-10-01

    In this study, It has been developed a Web-based collaboration framework which can be a flexible connection between macroscopically virtual environment and the physical environment. This framework is able to verifiy and manage physical environments. Also it can resolve the bottlenecks encountered during the base expansion and development process of IoT (Internet of Things environment.

  6. Research on Construction Technique of Computing Platform of Collaborative Simulation for Electromagnetic Characteristics Target%目标电磁特性协同仿真计算平台构建技术研究

    Institute of Scientific and Technical Information of China (English)

    刘民; 朱兴国; 刘姜玲; 黄飞龙

    2015-01-01

    In order to solve the bottleneck of computation of an electrically large target electromagnetic characteristics with complex struc-ture,put forward the connotation of electromagnetic grid computing and electromagnetic computing grid architecture and design. Through the integration of various electromagnetic algorithm,using the next generation advanced Internet and collaborative computing technology for seamless connectivity,resource aggregation and computation task distribution,scheduling and management to a number of different types and use of computing resources,model resources,algorithm resource and cyber resource from universities and research institutes, build collaborative simulation computing platform of electromagnetic, forming the distributed electromagnetic computing networks and cloud computing service system,through a number of collaborative computing nodes to complete the simulation calculation tasks and a-chieve collaborative work of wide area distribution of resources. The platform has the scalability,high availability,high computational ef-ficiency,effective scheduling and powerful computation ability. Finally,the conclusion and the prospects for the next step of work are giv-en.%为解决具有复杂结构超电大尺寸目标电磁特征计算的瓶颈,提出了电磁网格计算的思想以及电磁计算网格的技术内涵、体系结构和设计方案。通过融合各种电磁算法,利用下一代先进互联网和协同计算技术将高校和研究院所的大量不同类型和用途的计算资源、模型资源、算法资源和网络资源进行无缝连接、资源聚合以及计算任务的分发、调度与管理,构建电磁协同仿真计算平台,形成分布式电磁计算网络和云计算服务体系,通过多个计算节点的协同工作来完成仿真计算任务,实现广域分布资源的协同工作。该平台具有可扩展性、高可用性、高计算效率、有效调度以及强大的计算能力。最

  7. Cloud and Grid: more connected than you might think?

    CERN Multimedia

    Stephanie McClellan

    2013-01-01

    You may perceive the grid and the cloud to be two separate technologies: the grid as physical hardware and the cloud as virtual hardware simulated by running software. So how are the grid and the cloud being integrated at CERN?   CERN Computer Centre. The LHC generates a large amount of data that needs to be stored, distributed and analysed. Grid technology is used for the mass physical data processing needed for the LHC supported by many data centres around the world as part of the Worldwide LHC Computing Grid. Beyond the technology itself, the Grid represents a collaboration of all these centres working towards a common goal. Cloud technology uses virtualisation techniques, which allow one physical machine to represent many virtual machines. This technology is being used today to develop and deploy a range of IT services (such as Service Now, a cloud hosted service), allowing for a great deal of operational flexibility. Such services are available at CERN through Openstack. &...

  8. Simulation and performance analysis of 110 kWp grid-connected photovoltaic system for residential building in India: A comparative analysis of various PV technology

    Directory of Open Access Journals (Sweden)

    Akash Kumar Shukla

    2016-11-01

    Full Text Available System simulation is necessary to investigate the feasibility of Solar PV system at a given location. This study is done to evaluate the feasibility of grid connected rooftop solar photovoltaic system for a residential Hostel building at MANIT, Bhopal, India (Latitude: 23° 16′ N, Longitude: 77° 36′ E. The study focuses on the use of Solargis PV Planner software as a tool to analyze the performance a 110 kWp solar photovoltaic rooftop plant and also compares the performances of different PV technologies based on simulated energy yield and performance ratio. Solargis proves to easy, fast, accurate and reliable software tool for the simulation of solar PV system.

  9. The StaggerGrid project

    DEFF Research Database (Denmark)

    Collet, Remo; Magic, Zazralt; Asplund, Martin

    2011-01-01

    In this contribution, we present the STAGGERGRID, a collaborative project for the construction of a comprehensive grid of time-dependent, three-dimensional (3-D), hydrodynamic model atmospheres of solar- and late-type stars with different effective temperatures, surface gravities, and chemical co...... of their possible applications to elemental abundance analysis of stellar spectra in the context of large observational surveys.......In this contribution, we present the STAGGERGRID, a collaborative project for the construction of a comprehensive grid of time-dependent, three-dimensional (3-D), hydrodynamic model atmospheres of solar- and late-type stars with different effective temperatures, surface gravities, and chemical...

  10. Simulation of synchronous direct driving wind turbine grid system%同步直驱风电机组并网系统仿真

    Institute of Scientific and Technical Information of China (English)

    孟昭亮; 程远; 邵文权; 王育华

    2015-01-01

    基于风电机组并网工作原理,研究永磁同步发电机(PMSG)和电压型PWM 逆变器的数学模型,提出采用七段式SVPWM 控制策略,以及外环电压控制和内环电流控制相结合的双闭环控制策略实现同步风力发电机的有功和无功的解耦控制。利用仿真软件Matlab/Simulink构建了完整的并网过程仿真模型。仿真结果表明,系统具有良好的动静态性能,为同步直驱风电机组并网提供参考。%On the basis of wind turbines grid working principle ,the permanent magnet synchro‐nous generator (PMSG) and mathematical models of voltage type PWM inverter are studied .By using seven‐segment SVPWM control strategy ,and outer voltage control and inner current con‐trol combines dual closed‐loop control strategy ,synchronous wind generator of active and reac‐tive power decoupling control is implemented .Using simulation software of Matlab/Simulink , a simulation model of complete grid process is built .Simulation results show that the system has good dynamic and static performance .It can be a reference for synchronous direct drive wind turbine grid .

  11. Lead grids

    CERN Multimedia

    1974-01-01

    One of the 150 lead grids used in the multiwire proportional chamber g-ray detector. The 0.75 mm diameter holes are spaced 1 mm centre to centre. The grids were made by chemical cutting techniques in the Godet Workshop of the SB Physics.

  12. The SCEC Broadband Platform: A Collaborative Open-Source Software Package for Strong Ground Motion Simulation and Validation

    Science.gov (United States)

    Silva, F.; Maechling, P. J.; Goulet, C. A.; Somerville, P.; Jordan, T. H.

    2014-12-01

    The Southern California Earthquake Center (SCEC) Broadband Platform is a collaborative software development project involving geoscientists, earthquake engineers, graduate students, and the SCEC Community Modeling Environment. The SCEC Broadband Platform (BBP) is open-source scientific software that can generate broadband (0-100Hz) ground motions for earthquakes, integrating complex scientific modules that implement rupture generation, low and high-frequency seismogram synthesis, non-linear site effects calculation, and visualization into a software system that supports easy on-demand computation of seismograms. The Broadband Platform operates in two primary modes: validation simulations and scenario simulations. In validation mode, the Platform runs earthquake rupture and wave propagation modeling software to calculate seismograms for a well-observed historical earthquake. Then, the BBP calculates a number of goodness of fit measurements that quantify how well the model-based broadband seismograms match the observed seismograms for a certain event. Based on these results, the Platform can be used to tune and validate different numerical modeling techniques. In scenario mode, the Broadband Platform can run simulations for hypothetical (scenario) earthquakes. In this mode, users input an earthquake description, a list of station names and locations, and a 1D velocity model for their region of interest, and the Broadband Platform software then calculates ground motions for the specified stations. Working in close collaboration with scientists and research engineers, the SCEC software development group continues to add new capabilities to the Broadband Platform and to release new versions as open-source scientific software distributions that can be compiled and run on many Linux computer systems. Our latest release includes 5 simulation methods, 7 simulation regions covering California, Japan, and Eastern North America, the ability to compare simulation results

  13. Towards trusted volunteer grid environments

    CERN Document Server

    Khemakhem, Maher; University, Sousse; Tunisia,; University, Manouba; Tunisia),; 10.5121/ijcnc.2010.2207

    2010-01-01

    Intensive experiences show and confirm that grid environments can be considered as the most promising way to solve several kinds of problems relating either to cooperative work especially where involved collaborators are dispersed geographically or to some very greedy applications which require enough power of computing or/and storage. Such environments can be classified into two categories; first, dedicated grids where the federated computers are solely devoted to a specific work through its end. Second, Volunteer grids where federated computers are not completely devoted to a specific work but instead they can be randomly and intermittently used, at the same time, for any other purpose or they can be connected or disconnected at will by their owners without any prior notification. Each category of grids includes surely several advantages and disadvantages; nevertheless, we think that volunteer grids are very promising and more convenient especially to build a general multipurpose distributed scalable enviro...

  14. Simulation of Reactive Power Imbalances in the Transmission Power Grid Threatened by the Problem of Voltage Instability

    OpenAIRE

    Robert Lis; Mirosław Łabuzek

    2013-01-01

    The reactive power balance in the transmission power grid depends on the reactive power produced by the power stations and the value generated by the capacitive power lines and static compensators. Reactive transmission losses become greater than shunt capacitive generation at the turning-point of voltage stability. Then lowering bus voltages drive EPS into voltage collapse point. The paper presents the balance of reactive power depending on the power demand growth, which is then used to esti...

  15. 单相光伏两级并网系统的MATLAB仿真研究%MPPT simulation study based on monophasic photovoltaic grid-connected system

    Institute of Scientific and Technical Information of China (English)

    黄成玉; 张全柱; 邓永红; 马红梅

    2011-01-01

    The control method of maximum power point tracking for photovoltaic power system was discussed in this article. The equivalent circuit of solar cells was presented by analyzing internal structure and volt-ampere characteristic of solar cells. The present simulation model of solar cell panel was built using MATLAB language. By analyzing the existing method of maximum power point tracking, a maximum power point tracking method based on average was proposed, and the post-stage grid-connected inverter circuit was analyzed, and the simulation model was presented. The result shows the method is of good practicability. The grid-connected requirement of low harmonic content and high power factor was realized by controlling the post-stage grid-connected inverter.%为了寻找更好的实现光伏发电系统最大功率点追踪控制方法,根据太阳电池的内部结构和伏安特性建立了太阳电池的等效电路,利用MATLAB语言建立了太阳电池板仿真模型.在分析已有最大功率追踪方法的基础上,提出了一种基于平均值控制的最大功率追踪方法,并对后级并网逆变电路进行理论分析和仿真实验,实验结果证明了所提出方法具有良好的实用性.通过对并网逆变器的控制实现了低谐波含量、高功率因数的并网要求.

  16. Grid Security

    CERN Document Server

    CERN. Geneva

    2004-01-01

    The aim of Grid computing is to enable the easy and open sharing of resources between large and highly distributed communities of scientists and institutes across many independent administrative domains. Convincing site security officers and computer centre managers to allow this to happen in view of today's ever-increasing Internet security problems is a major challenge. Convincing users and application developers to take security seriously is equally difficult. This paper will describe the main Grid security issues, both in terms of technology and policy, that have been tackled over recent years in LCG and related Grid projects. Achievements to date will be described and opportunities for future improvements will be addressed.

  17. Video conference platforms: A tool to foster collaboration during inter-organizational in vivo simulations

    Directory of Open Access Journals (Sweden)

    Cecilia Lemus-Martinez

    2011-10-01

    Full Text Available Inter-organizational problem solving of emergencies and extreme events are complex research fields where scarce experimental data is available. To address this problem, the Inter-GAP In Vivo System, was developed to run behavioural experiments of complex crisis. The system design and testing included three categories of participants: for pilot testing, first year university students; for theoretical validity, college students engaged in emergency management programs; and for field validity, expert decision makers who managed major crises. A comparative assessment was performed to select the most suitable video conferencing software commercially available, since it was more cost-efficient to acquire a tool already developed and customized it to the experiment needs than it was to design a new one. Software features analyzed were: ease of use, recording capabilities, format delivery options and security. The Inter-GAP In Vivo System setup was implemented on the video conference platform selected. The system performance was evaluated at three levels: technical setup, task design and work flow processes. The actual experimentation showed that the conferencing software is a versatile tool to enhance collaboration between stakeholders from different organizations, due to the audiovisual contact participants can establish, where non verbal cues can be interchanged along the problem solving processes. Potential future system applications include: collaborative and cross – functional training between organizations.

  18. Microsoft Kinect based head tracking for Life Size Collaborative Surgical Simulation Environments (LS-CollaSSLE).

    Science.gov (United States)

    Dargar, Saurabh; Nunno, Austin; Sankaranarayanan, Ganesh; De, Suvranu

    2013-01-01

    Virtual surgical skills trainers are proving to be very useful for the medical training community. With efforts to increase patient safety and surgeon expertise, the need for surgical skills trainers that provide training in an operating room (OR) like condition is now more pressing. To allow for virtual surgery simulators to be instructed in an OR-like setting we have created a large display based immersive surgical simulation environment. Using the Microsoft Kinect we have created a real-time simulation environment that tracks the test user and appropriately adjust the perspective of the virtual OR for an immersive virtual experience.

  19. 太阳能光伏发电并网模拟装置的研究%Research on simulated devices for photovoltaic grid-connected generation system

    Institute of Scientific and Technical Information of China (English)

    彭其泽; 张全柱

    2012-01-01

    On the standpoint of energy conservation and emission reduction, one device simulating the photovoltaic grid-connected generation system based on SPWM was designed in the paper. And DC/AC inverter could transduce efficiently direct current to alternating current. The MCU (micro-control-unit), in this system could achieve the control method for maximum-power-point and tracking for frequency and phase. Moreover, the MCU could implement PWM (plus-width modulating) through programming. The system showed clearly the whole photovoltaic grid-connected generation system using simulated methods and ways.%从节能减排的角度出发,设计了一种基于SPWM技术的光伏并网发电模拟装置,DC/AC逆变可以有效地进行直流至交流的转换.系统通过单片机编程的方式实现了最大功率点控制、频率和相位的跟踪.同时单片机还能通过编程方式实现PWM脉冲宽度调制.本系统最大的特点是用模拟的方式简明地介绍了整个光伏并网发电系统.

  20. CFD simulation of near-field pollutant dispersion on a high-resolution grid: A case study by LES and RANS for a building group in downtown Montreal

    Science.gov (United States)

    Gousseau, P.; Blocken, B.; Stathopoulos, T.; van Heijst, G. J. F.

    2011-01-01

    Turbulence modeling and validation by experiments are key issues in the simulation of micro-scale atmospheric dispersion. This study evaluates the performance of two different modeling approaches (RANS standard k-ɛ and LES) applied to pollutant dispersion in an actual urban environment: downtown Montreal. The focus of the study is on near-field dispersion, i.e. both on the prediction of pollutant concentrations in the surrounding streets (for pedestrian outdoor air quality) and on building surfaces (for ventilation system inlets and indoor air quality). The high-resolution CFD simulations are performed for neutral atmospheric conditions and are validated by detailed wind-tunnel experiments. A suitable resolution of the computational grid is determined by grid-sensitivity analysis. It is shown that the performance of the standard k-ɛ model strongly depends on the turbulent Schmidt number, whose optimum value is case-dependent and a priori unknown. In contrast, LES with the dynamic subgrid-scale model shows a better performance without requiring any parameter input to solve the dispersion equation.

  1. Globally Collaborative Experiential Learning

    Directory of Open Access Journals (Sweden)

    Takeshi UTSUMI

    2005-07-01

    Full Text Available ABSTRACT The Global University System (GUS [Utsumi, et al, 2003] is a worldwide initiative to create advanced telecommunications infrastructure for access to educational resources across national and cultural boundaries for global peace. GUS aims to create a worldwide consortium of universities to provide the underdeveloped world with access to 21st Century education via broadband Internet technologies. The aim is to achieve “education and healthcare for all,” anywhere, anytime and at any pace. The GUS works in the major regions of the globe with partnerships of higher education and healthcare institutions. Learners in these regions will be able to take their courses from member institutions around the world to receive a GUS degree. These learners and their professors from partner institutions will also form a global forum for exchange of ideas and information and for conducting collaborative research and development with emerging global GRID computer network technology. Globally Collaborative Environmental Peace Gaming (GCEPG project [Utsumi, 2003] with a globally distributed computer simulation system, focusing on the issue of environment and sustainable development in developing countries, is to train would-be decision-makers in crisis management, conflict resolution, and negotiation techniques basing on “facts and figures.” The GUS will supply game players from around the world.

  2. 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.

  3. Moose: An Open-Source Framework to Enable Rapid Development of Collaborative, Multi-Scale, Multi-Physics Simulation Tools

    Science.gov (United States)

    Slaughter, A. E.; Permann, C.; Peterson, J. W.; Gaston, D.; Andrs, D.; Miller, J.

    2014-12-01

    The Idaho National Laboratory (INL)-developed Multiphysics Object Oriented Simulation Environment (MOOSE; www.mooseframework.org), is an open-source, parallel computational framework for enabling the solution of complex, fully implicit multiphysics systems. MOOSE provides a set of computational tools that scientists and engineers can use to create sophisticated multiphysics simulations. Applications built using MOOSE have computed solutions for chemical reaction and transport equations, computational fluid dynamics, solid mechanics, heat conduction, mesoscale materials modeling, geomechanics, and others. To facilitate the coupling of diverse and highly-coupled physical systems, MOOSE employs the Jacobian-free Newton-Krylov (JFNK) method when solving the coupled nonlinear systems of equations arising in multiphysics applications. The MOOSE framework is written in C++, and leverages other high-quality, open-source scientific software packages such as LibMesh, Hypre, and PETSc. MOOSE uses a "hybrid parallel" model which combines both shared memory (thread-based) and distributed memory (MPI-based) parallelism to ensure efficient resource utilization on a wide range of computational hardware. MOOSE-based applications are inherently modular, which allows for simulation expansion (via coupling of additional physics modules) and the creation of multi-scale simulations. Any application developed with MOOSE supports running (in parallel) any other MOOSE-based application. Each application can be developed independently, yet easily communicate with other applications (e.g., conductivity in a slope-scale model could be a constant input, or a complete phase-field micro-structure simulation) without additional code being written. This method of development has proven effective at INL and expedites the development of sophisticated, sustainable, and collaborative simulation tools.

  4. Using simulation to educate police about mental illness: A collaborative initiative

    Directory of Open Access Journals (Sweden)

    Wendy Stanyon

    2014-06-01

    Full Text Available Mental illness is a major public health concern in Canada and also globally. According to the World Health Organization, five of the top ten disabilities worldwide are mental health disorders. Within Canada, one in five individuals is living with mental illness each year. Currently, there are 6.7 million Canadians living with mental illness and over 1 million Canadian youth living with mental illness. Police are frequently the first responders to situations in the community involving people with mental illness, and police services are increasingly aware of the need to provide officers with additional training and strategies for effectively interacting with these citizens. This study examined the effectiveness of four online, interactive video-based simulations designed to educate police officers about mental illness and strategies for interacting with people with mental illness. The simulations were created through the efforts of a unique partnership involving a police service, a mental health facility and two postsecondary institutions. Frontline police officers from Ontario were divided into one of three groups (simulation, face to face, control. Using a pre- and post-test questionnaire, the groups were compared on their level of knowledge and understanding of mental illness. In addition, focus groups explored the impact of the simulations on officers’ level of confidence in engaging with individuals with mental illness and officers’ perceptions of the simulations’ ease of use and level of realism. The study’s findings determined that the simulations were just as effective as face-to-face learning, and the officers reported the simulations were easy to use and reflected real-life scenarios they had encountered on the job. As mental health continues to be a major public concern, not only in Canada but also globally, interactive simulations may provide an effective and affordable education resource not only for police officers but for

  5. Grid oscillators

    Science.gov (United States)

    Popovic, Zorana B.; Kim, Moonil; Rutledge, David B.

    1988-01-01

    Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

  6. Decentralized resource brokering for heterogeneous grid environments

    OpenAIRE

    2006-01-01

    The emergence of Grid computing infrastructures enables researchers to share resources and collaborate in more efficient ways than before, despite belonging to different organizations and being distanced geographically. While the Grid computing paradigm offers new opportunities, it also gives rise to new difficulties. One such problem is the selection of resources for user applications. Given the large and disparate set of Grid resources, manual resource selection becomes impractical, even fo...

  7. How Group Size and Composition Influences the Effectiveness of Collaborative Screen-Based Simulation Training: A Study of Dental and Nursing University Students Learning Radiographic Techniques

    Directory of Open Access Journals (Sweden)

    Tor Söderström

    2012-12-01

    Full Text Available This study analyses how changes in the design of screen-based computer simulation training influence the collaborative training process. Specifically, this study examine how the size of a group and a group’s composition influence the way these tools are used. One case study consisted of 18+18 dental students randomized into either collaborative 3D simulation training or conventional collaborative training. The students worked in groups of three. The other case consisted of 12 nursing students working in pairs (partners determined by the students with a 3D simulator. The results showed that simulation training encouraged different types of dialogue compared to conventional training and that the communication patterns were enhanced in the nursing students ́ dyadic simulation training. The concrete changes concerning group size and the composition of the group influenced the nursing students’ engagement with the learning environment and consequently the communication patterns that emerged. These findings suggest that smaller groups will probably be more efficient than larger groups in a free collaboration setting that uses screen-based simulation training.

  8. Grid attacks avian flu

    CERN Multimedia

    2006-01-01

    During April, a collaboration of Asian and European laboratories analysed 300,000 possible drug components against the avian flu virus H5N1 using the EGEE Grid infrastructure. Schematic presentation of the avian flu virus.The distribution of the EGEE sites in the world on which the avian flu scan was performed. The goal was to find potential compounds that can inhibit the activities of an enzyme on the surface of the influenza virus, the so-called neuraminidase, subtype N1. Using the Grid to identify the most promising leads for biological tests could speed up the development process for drugs against the influenza virus. Co-ordinated by CERN and funded by the European Commission, the EGEE project (Enabling Grids for E-sciencE) aims to set up a worldwide grid infrastructure for science. The challenge of the in silico drug discovery application is to identify those molecules which can dock on the active sites of the virus in order to inhibit its action. To study the impact of small scale mutations on drug r...

  9. Simulations of Kinetic Electrostatic Electron Nonlinear (KEEN) Waves with Variable Velocity Resolution Grids and High-Order Time-Splitting

    CERN Document Server

    Afeyan, Bedros; Crouseilles, Nicolas; Dodhy, Adila; Faou, Erwan; Mehrenberger, Michel; Sonnendrücker, Eric

    2014-01-01

    KEEN waves are nonlinear, non-stationary, self-organized asymptotic states in Vlasov plasmas outside the scope or purview of linear theory constructs such as electron plasma waves or ion acoustic waves. Nonlinear stationary mode theories such as those leading to BGK modes also do not apply. The range in velocity that is strongly perturbed by KEEN waves depends on the amplitude and duration of the ponderomotive force used to drive them. Smaller amplitude drives create highly localized structures attempting to coalesce into KEEN waves. These cases have much more chaotic and intricate time histories than strongly driven ones. The narrow range in which one must maintain adequate velocity resolution in the weakly driven cases challenges xed grid numerical schemes. What is missing there is the capability of resolving locally in velocity while maintaining a coarse grid outside the highly perturbed region of phase space. We here report on a new Semi-Lagrangian Vlasov-Poisson solver based on conservative non-uniform c...

  10. Modeling, control, and simulation of grid connected intelligent hybrid battery/photovoltaic system using new hybrid fuzzy-neural method.

    Science.gov (United States)

    Rezvani, Alireza; Khalili, Abbas; Mazareie, Alireza; Gandomkar, Majid

    2016-07-01

    Nowadays, photovoltaic (PV) generation is growing increasingly fast as a renewable energy source. Nevertheless, the drawback of the PV system is its dependence on weather conditions. Therefore, battery energy storage (BES) can be considered to assist for a stable and reliable output from PV generation system for loads and improve the dynamic performance of the whole generation system in grid connected mode. In this paper, a novel topology of intelligent hybrid generation systems with PV and BES in a DC-coupled structure is presented. Each photovoltaic cell has a specific point named maximum power point on its operational curve (i.e. current-voltage or power-voltage curve) in which it can generate maximum power. Irradiance and temperature changes affect these operational curves. Therefore, the nonlinear characteristic of maximum power point to environment has caused to development of different maximum power point tracking techniques. In order to capture the maximum power point (MPP), a hybrid fuzzy-neural maximum power point tracking (MPPT) method is applied in the PV system. Obtained results represent the effectiveness and superiority of the proposed method, and the average tracking efficiency of the hybrid fuzzy-neural is incremented by approximately two percentage points in comparison to the conventional methods. It has the advantages of robustness, fast response and good performance. A detailed mathematical model and a control approach of a three-phase grid-connected intelligent hybrid system have been proposed using Matlab/Simulink.

  11. Tema 1: Refitting existing simulations to meet with new learning objectives – from supply chain management to virtual collaboration

    Directory of Open Access Journals (Sweden)

    Timo Leinema

    2012-10-01

    Full Text Available This paper discusses the application possibilities of business simulation games in teaching. By application possibilities we mean the different ways of arranging the learning sessions using the one and same simulation game. Thus, we are not discussing what kind of games should be built for certain educational purposes, or how a game should be built to facilitate certain kind of learning experiences. Our assumption is that a certain game can be applied in different manners to produce very different kinds of learning experiences, serving very diverse learning goals. We are interested in how the learning potential of existing games can be expanded without making any changes in the actual game algorithms, but by rethinking the activities around the game. In this paper we discuss the shift from intra-team learning to inter-team learning, and especially further to learning which is based on dispersed inter-team collaboration in a virtual environment. We will demonstrate our message with one specific, existing business simulation game.

  12. Tema 1: Refitting existing simulations to meet with new learning objectives – from supply chain management to virtual collaboration

    Directory of Open Access Journals (Sweden)

    Timo Leinema

    2012-10-01

    Full Text Available This paper discusses the application possibilities of business simulation games in teaching. By application possibilities we mean the different ways of arranging the learning sessions using the one and same simulation game. Thus, we are not discussing what kind of games should be built for certain educational purposes, or how a game should be built to facilitate certain kind of learning experiences. Our assumption is that a certain game can be applied in different manners to produce very different kinds of learning experiences, serving very diverse learning goals. We are interested in how the learning potential of existing games can be expanded without making any changes in the actual game algorithms, but by rethinking the activities around the game. In this paper we discuss the shift from intra-team learning to inter-team learning, and especially further to learning which is based on dispersed inter-team collaboration in a virtual environment. We will demonstrate our message with one specific, existing business simulation game.

  13. SEMICONDUCTOR DEVICES: Optimization of grid design for solar cells

    Science.gov (United States)

    Wen, Liu; Yueqiang, Li; Jianjun, Chen; Yanling, Chen; Xiaodong, Wang; Fuhua, Yang

    2010-01-01

    By theoretical simulation of two grid patterns that are often used in concentrator solar cells, we give a detailed and comprehensive analysis of the influence of the metal grid dimension and various losses directly associated with it during optimization of grid design. Furthermore, we also perform the simulation under different concentrator factors, making the optimization of the front contact grid for solar cells complete.

  14. Teacher's Skill Improvement by Role-Play and Simulations on Collaborative Educational Virtual Worlds

    Science.gov (United States)

    Lorenzo, Carlos-Miguel

    2014-01-01

    This study looked at teachers' role-play and simulations in order to increase teachers' skills in psycho-pedagogical support on educational virtual worlds. We put forward a proposal to encourage the use of 3D scenarios where teachers can improve their skills for situations of cultural and ethical concerns that require a high level…

  15. Increase in the number of distributed power generation installations in electricity distribution grids - Simulation in a 16 kV medium-voltage network; Zunahme der dezentralen Energieerzeugungsanlagen in elektrischen Verteilnetzen: Simulationen im 16 kV Mittelspannungsnetz des AEW

    Energy Technology Data Exchange (ETDEWEB)

    Hoeckel, M.; Luechinger, P.

    2003-07-01

    This is the seventh part of a ten-part final report for the Swiss Federal Office of Energy (SFOE) on a project that looked into potential problems relating to the Swiss electricity distribution grid with respect to the increasing number of distributed power generation facilities being put into service. The identification of special conditions for the grid's operation and future development that take increasing decentralised power production into account are discussed. The results of the project activities encompass the analysis and evaluation of various problem areas associated with planning and management of the grid during normal operation and periods of malfunction, as well as required modifications to safety systems and grid configurations. This sixth appendix to the main report presents and discusses the results of simulations made on the basis of the real-life 16 kV medium-voltage distribution network operated by the Aargovian electricity utility AEW. This appendix describes the simulation methods used and the basic characteristics of medium-voltage networks and distributed generation facilities. Different types of load profiles, including domestic and industrial loads, are discussed. The results of the simulations are presented in graphical form and provide profiles of voltage and current, active and reactive power and further mains characteristics for varying load conditions. Also, daily profiles for situations with and without distributed generation are presented and short-circuit simulations and grid dynamics are discussed.

  16. Wave simulation in 2D heterogeneous transversely isotropic porous media with fractional attenuation: A Cartesian grid approach

    Science.gov (United States)

    Blanc, Emilie; Chiavassa, Guillaume; Lombard, Bruno

    2014-10-01

    A time-domain numerical modeling of transversely isotropic Biot poroelastic waves is proposed in two dimensions. The viscous dissipation occurring in the pores is described using the dynamic permeability model developed by Johnson-Koplik-Dashen (JKD). Some of the coefficients in the Biot-JKD model are proportional to the square root of the frequency. In the time-domain, these coefficients introduce shifted fractional derivatives of order 1/2, involving a convolution product. Based on a diffusive representation, the convolution kernel is replaced by a finite number of memory variables that satisfy local-in-time ordinary differential equations, resulting in the Biot-DA (diffusive approximation) model. The properties of both the Biot-JKD and the Biot-DA models are analyzed: hyperbolicity, decrease of energy, dispersion. To determine the coefficients of the diffusive approximation, two approaches are analyzed: Gaussian quadratures and optimization methods in the frequency range of interest. The nonlinear optimization is shown to be the better way of determination. A splitting strategy is then applied to approximate numerically the Biot-DA equations. The propagative part is discretized using a fourth-order ADER scheme on a Cartesian grid, whereas the diffusive part is solved exactly. An immersed interface method is implemented to take into account heterogeneous media on a Cartesian grid and to discretize the jump conditions at interfaces. Numerical experiments are presented. Comparisons with analytical solutions show the efficiency and the accuracy of the approach, and some numerical experiments are performed to investigate wave phenomena in complex media, such as multiple scattering across a set of random scatterers.

  17. Enhancement of Collaboration and Communication between Design and Simulation Departments by Methods of Requirements Engineering

    OpenAIRE

    Schweigert, Sebastian; D'Albert, Hugo; Lindemann, Udo

    2016-01-01

    Simulation techniques like FEM and CFD have become a standard part of the engineering design process with an increasingly important role [Maier et al. 2009]. According to Herfeld et al. [2006], five aspects have to be considered when dealing with the integration of Computer Aided Engineering (CAE) tools into Computer Aided Design (CAD): product, people, tools, data, and processes. While a lot of research has been conducted on technical aspects in this context (e.g. [Forsen and Hoffmann 2002],...

  18. Simulated Partners and Collaborative Exercise (SPACE) to boost motivation for astronauts: study protocol

    OpenAIRE

    Feltz, Deborah L.; Ploutz-Snyder, Lori; Winn, Brian; Kerr, Norbert L.; Pivarnik, James M; Ede, Alison; Hill, Christopher; Samendinger, Stephen; Jeffery, William

    2016-01-01

    Background Astronauts may have difficulty adhering to exercise regimens at vigorous intensity levels during long space missions. Vigorous exercise is important for aerobic and musculoskeletal health during space missions and afterwards. A key impediment to maintaining vigorous exercise is motivation. Finding ways to motivate astronauts to exercise at levels necessary to mitigate reductions in musculoskeletal health and aerobic capacity have not been explored. The focus of Simulated Partners a...

  19. 不平衡电网条件下建模与仿真研究%Research on Modeling and Simulation of DFIG under Unbalanced Grid Conditions

    Institute of Scientific and Technical Information of China (English)

    郑飘飘; 梁俊宇; 赵明; 李传斌

    2015-01-01

    For analyzing the weakening control ability of DFIG which use the traditional vector control strategy under unbalanced grid conditions and improve the fault ride-through capability, the mathematical model are established for the rotor side and the grid side converter of DFIG. The dynamic behaviors of DFIG during asymmetrical grid fault are firstly analyzed. The rotor side and the grid side converter are modeled based on double d-q positive and negative sequence decomposition in Simulink and the simulation results are compared with the traditional one. The results show that the oscillation of power output could be effectively restrained with this improved control strategy. The over current and voltage of the rotor winding are also reduced. Moreover, the endurance ability and operating stability are enhanced.%为了准确分析不平衡电网条件下, DFIG机组使用传统矢量控制策略而引发控制能力下降的原因,并改善DFIG机组的故障穿越能力,建立了DFIG机组转子侧变换器和网侧变换器的数学模型。首先分析了故障下DFIG机组的动态变化过程。针对电网电压不对称故障,在Simulink环境下搭建了基于双d-q正、负序分解的转子侧及网侧变换器模型,并将传统的控制策略与改进控制策略进行仿真对比。仿真结果表明,改进的控制策略可以有效地抑制有功、无功的二倍频波动,减小过电压和过电流,增强机组对电网故障冲击承受能力,提高DFIG机组运行的稳定性。

  20. Smart Grid Integration Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Troxell, Wade [Colorado State Univ., Fort Collins, CO (United States)

    2011-12-22

    The initial federal funding for the Colorado State University Smart Grid Integration Laboratory is through a Congressionally Directed Project (CDP), DE-OE0000070 Smart Grid Integration Laboratory. The original program requested in three one-year increments for staff acquisition, curriculum development, and instrumentation all which will benefit the Laboratory. This report focuses on the initial phase of staff acquisition which was directed and administered by DOE NETL/ West Virginia under Project Officer Tom George. Using this CDP funding, we have developed the leadership and intellectual capacity for the SGIC. This was accomplished by investing (hiring) a core team of Smart Grid Systems engineering faculty focused on education, research, and innovation of a secure and smart grid infrastructure. The Smart Grid Integration Laboratory will be housed with the separately funded Integrid Laboratory as part of CSU's overall Smart Grid Integration Center (SGIC). The period of performance of this grant was 10/1/2009 to 9/30/2011 which included one no cost extension due to time delays in faculty hiring. The Smart Grid Integration Laboratory's focus is to build foundations to help graduate and undergraduates acquire systems engineering knowledge; conduct innovative research; and team externally with grid smart organizations. Using the results of the separately funded Smart Grid Workforce Education Workshop (May 2009) sponsored by the City of Fort Collins, Northern Colorado Clean Energy Cluster, Colorado State University Continuing Education, Spirae, and Siemens has been used to guide the hiring of faculty, program curriculum and education plan. This project develops faculty leaders with the intellectual capacity to inspire its students to become leaders that substantially contribute to the development and maintenance of Smart Grid infrastructure through topics such as: (1) Distributed energy systems modeling and control; (2) Energy and power conversion; (3

  1. Grid reliability

    Science.gov (United States)

    Saiz, P.; Andreeva, J.; Cirstoiu, C.; Gaidioz, B.; Herrala, J.; Maguire, E. J.; Maier, G.; Rocha, R.

    2008-07-01

    Thanks to the Grid, users have access to computing resources distributed all over the world. The Grid hides the complexity and the differences of its heterogeneous components. In such a distributed system, it is clearly very important that errors are detected as soon as possible, and that the procedure to solve them is well established. We focused on two of its main elements: the workload and the data management systems. We developed an application to investigate the efficiency of the different centres. Furthermore, our system can be used to categorize the most common error messages, and control their time evolution.

  2. Equivalent Simplification Method of Micro-Grid

    Directory of Open Access Journals (Sweden)

    Cai Changchun

    2013-09-01

    Full Text Available The paper concentrates on the equivalent simplification method for the micro-grid system connection into distributed network. The equivalent simplification method proposed for interaction study between micro-grid and distributed network. Micro-grid network, composite load, gas turbine synchronous generation, wind generation are equivalent simplification and parallel connect into the point of common coupling. A micro-grid system is built and three phase and single phase grounded faults are performed for the test of the equivalent model of micro-grid. The simulation results show that the equivalent model of micro-grid is effective, and the dynamic of equivalent model is similar with the detailed model of micro-grid. The equivalent simplification method for the micro-grid network and distributed components is suitable for the study of micro-grid.  

  3. Automatic Transaction Compensation for Reliable Grid Applications

    Institute of Scientific and Technical Information of China (English)

    Fei-Long Tang; Ming-Lu Li; Joshua Zhexue Huang

    2006-01-01

    As grid technology is expanding from scientific computing to business applications, service oriented grid computing is aimed at providing reliable services for users and hiding complexity of service processes from them. The grid services for coordinating long-lived transactions that occur in business applications play an important role in reliable grid applications. In this paper, the grid transaction service (GridTS) is proposed for dealing with long-lived business transactions. We present a compensation-based long-lived transaction coordination algorithm that enables users to select results from committed sub-transactions. Unlike other long-lived transaction models that require application programmers to develop corresponding compensating transactions, GridTS can automatically generate compensating transactions on execution of a long-lived grid transaction. The simulation result has demonstrated the feasibility of GridTS and effectiveness of the corresponding algorithm.

  4. Effect of hospital simulation tutorials on nursing and pharmacy student perception of interprofessional collaboration: Findings from a pilot study.

    Science.gov (United States)

    Stehlik, Paulina; Frotjold, Astrid; Schneider, Carl R

    2017-09-18

    Interprofessional learning (IPL) during formal training enables interprofessional collaboration (IPC) in the workforce; however, on-campus IPL opportunities are seldom incorporated into curricula. We describe the development and implementation of two hospital simulation tutorials between nursing and pharmacy students. Students were required to provide "usual care" to a simulated patient at admission and discharge. A pre-post survey design was used to evaluate changes in Interdisciplinary Education Perception Scale (IEPS) score and student perceived educational value of the tutorials. The tutorials had a positive effect on IEPS scores (p < 0.001), whereas gender and profession did not appear to influence scores (p = 0.082 and p = 0.923, respectively). Tutorials were rated either good or very good by 89.9% of students and 79.6% of students reporting new insights into the other profession This tutorial format could be easily adapted by other institutions as an engaging and rewarding strategy to better prepare students for IPC the workforce.

  5. 基于SIMULINK与FLUENT的协同仿真%Collaborative Simulation Based on SIMULINK and FLU-ENT

    Institute of Scientific and Technical Information of China (English)

    刘辉玲

    2015-01-01

    According to the user redevelopment characteristics of FLUENT's UDF and SIMULINK's S function,this paper gives the communication method of FLUENT and SIMULINK based on Winsock network communication to realize their collaborative simulation. First, this paper gives the specific steps on the basis of programming rule of FLUENT's UDF and SIMULINK's S function to achieve their communications. Then, taking adsorptive hydrogen storage in hydrogen storage tank as an example, it real-izes the interaction of the pressure value of each iterative step by the two kinds of software simulation, thus proving the feasibility and practicability of the method.%本文依据FLUENT UDF 和SIMULINK S函数可二次开发的特点,提出了基于Winsock网络通信的方法,实现FLUENT 和 SIMULINK的协同仿真。本文首先结合 FLUENT UDF和SIMULINK S函数的编程规则,给出了两者通信的具体实现步骤。然后,以储氢罐吸附储氢 FLUENT模拟和SIMULINK模拟为例,实现了两种模拟每个迭代步中压力值的交互,验证了两者交互的可行性和实用性。

  6. Power grid reliability and security

    Energy Technology Data Exchange (ETDEWEB)

    Bose, Anjan [Washington State Univ., Pullman, WA (United States); Venkatasubramanian, Vaithianathan [Washington State Univ., Pullman, WA (United States); Hauser, Carl [Washington State Univ., Pullman, WA (United States); Bakken, David [Washington State Univ., Pullman, WA (United States); Anderson, David [Washington State Univ., Pullman, WA (United States); Zhao, Chuanlin [Washington State Univ., Pullman, WA (United States); Liu, Dong [Washington State Univ., Pullman, WA (United States); Yang, Tao [Washington State Univ., Pullman, WA (United States); Meng, Ming [Washington State Univ., Pullman, WA (United States); Zhang, Lin [Washington State Univ., Pullman, WA (United States); Ning, Jiawei [Washington State Univ., Pullman, WA (United States); Tashman, Zaid [Washington State Univ., Pullman, WA (United States)

    2015-01-31

    This project has led to the development of a real-time simulation platform for electric power grids called Grid Simulator or GridSim for simulating the dynamic and information network interactions of large- scale power systems. The platform consists of physical models of power system components including synchronous generators, loads and control, which are simulated using a modified commercial power simulator namely Transient Stability Analysis Tool (TSAT) [1] together with data cleanup components, as well as an emulated substation level and wide-area power analysis components. The platform also includes realistic representations of communication network middleware that can emulate the real-time information flow back and forth between substations and control centers in wide-area power systems. The platform has been validated on a realistic 6000-bus model of the western American power system. The simulator GridSim developed in this project is the first of its kind in its ability to simulate real-time response of large-scale power grids, and serves as a cost effective real-time stability and control simulation platform for power industry.

  7. POWER GRID RELIABILITY AND SECURITY

    Energy Technology Data Exchange (ETDEWEB)

    Bose, Anjan; Venkatasubramanian, Vaithianathan; Hauser, Carl; Bakken, David; Anderson, David; Zhao, Chuanlin; Liu, Dong; Yang, Tao; Meng, Ming; Zhang, Lin; Ning, Jiawei; Tashman, Zaid

    2014-09-30

    This project has led to the development of a real-time simulation platform for electric power grids called Grid Simulator or GridSim for simulating the dynamic and information network interactions of large- scale power systems. The platform consists of physical models of power system components including synchronous generators, loads and control, which are simulated using a modified commercial power simulator namely Transient Stability Analysis Tool (TSAT) [1] together with data cleanup components, as well as an emulated substation level and wide-area power analysis components. The platform also includes realistic representations of communication network middleware that can emulate the real-time information flow back and forth between substations and control centers in wide-area power systems. The platform has been validated on a realistic 6000-bus model of the western American power system. The simulator GridSim developed in this project is the first of its kind in its ability to simulate real-time response of large-scale power grids, and serves as a cost effective real-time stability and control simulation platform for power industry.

  8. Verification of the coupled fluid/solid transfer in a CASL grid-to-rod-fretting simulation : a technical brief on the analysis of convergence behavior and demonstration of software tools for verification.

    Energy Technology Data Exchange (ETDEWEB)

    Copps, Kevin D.

    2011-12-01

    For a CASL grid-to-rod fretting problem, Sandia's Percept software was used in conjunction with the Sierra Mechanics suite to analyze the convergence behavior of the data transfer from a fluid simulation to a solid mechanics simulation. An analytic function, with properties relatively close to numerically computed fluid approximations, was chosen to represent the pressure solution in the fluid domain. The analytic pressure was interpolated on a sequence of grids on the fluid domain, and transferred onto a separate sequence of grids in the solid domain. The error in the resulting pressure in the solid domain was measured with respect to the analytic pressure. The error in pressure approached zero as both the fluid and solids meshes were refined. The convergence of the transfer algorithm was limited by whether the source grid resolution was the same or finer than the target grid resolution. In addition, using a feature coverage analysis, we found gaps in the solid mechanics code verification test suite directly relevant to the prototype CASL GTRF simulations.

  9. Offshore code comparison collaboration continuation (OC4), phase I - Results of coupled simulations of an offshore wind turbine with jacket support structure

    DEFF Research Database (Denmark)

    Popko, Wojciech; Vorpahl, Fabian; Zuga, Adam;

    2012-01-01

    In this paper, the exemplary results of the IEA Wind Task 30 "Offshore Code Comparison Collaboration Continuation" (OC4) Project - Phase I, focused on the coupled simulation of an offshore wind turbine (OWT) with a jacket support structure, are presented. The focus of this task has been...

  10. Effect of grid size in RCMs on the representation of floods in small and medium sized catchments in Austria: added value of convection-permitting simulations

    Science.gov (United States)

    Reszler, Christian; Truhetz, Heimo; Switanek, Matthew

    2016-04-01

    This paper presents a small multi-model ensemble study of coupling two different ERA-Interim driven RCMs (WRF and COSMO-CLM) using different grid sizes (0.44°, 0.11°, 0.03°) with a hydrological model for representing floods in small to medium sized catchments in South-eastern Austria. The aim is to evaluate the benefit of grid size reduction and in particular, the added value of convection-permitting simulations with 0.03° (~ 3 km) resolution. The hydrological model is a spatially distributed model (1 km² grid), which was previously developed for operational flood forecasting and calibrated against data of more than 20 stream gauges with corresponding catchment sizes between 30 and 1000 km². The hindcast simulations (1989-2010) are evaluated in terms of accurately representing flood frequency, seasonality, as well as other flood event characteristics, such as weather type, antecedent soil moisture, etc. The results show, that for small catchments (frequency and seasonality is represented well in all catchments. In the larger catchments a resolution of 0.11° (~ 12.5 km) already yields statistically satisfying results. Also, due to the short response times in the small sub-catchments a time step of 1 hour is required. However, in all setups a bias still exists in precipitation and temperature, which sometimes leads to unrealistic hydrological conditions. Ongoing work comprises the test a of novel statistical error correction method, which is expected to improve results particularly for higher quantiles. Also, a future run ("time-slice" experiment) is planned with the coupled model setup using the RCP8.5 emission scenario, the GCM of the Max-Planck-Institute Hamburg (MPI-ESM-LR), dynamically downscaled to 3 km by COSMO-CLM, and the novel error correction method. The study is funded by the Austrian Klima- und Energiefonds through the Austrian Climate Research Programme (ACRP) by means of the project CHC-FloodS (id KR13AC6K11102). Further support is also received

  11. A principled approach to grid middleware

    DEFF Research Database (Denmark)

    Berthold, Jost; Bardino, Jonas; Vinter, Brian

    2011-01-01

    This paper provides an overview of MiG, a Grid middleware for advanced job execution, data storage and group collaboration in an integrated, yet lightweight solution using standard software. In contrast to most other Grid middlewares, MiG is developed with a particular focus on usability and mini......This paper provides an overview of MiG, a Grid middleware for advanced job execution, data storage and group collaboration in an integrated, yet lightweight solution using standard software. In contrast to most other Grid middlewares, MiG is developed with a particular focus on usability...... and minimal system requirements, applying strict principles to keep the middleware free of legacy burdens and overly complicated design. We provide an overview of MiG and describe its features in view of the Grid vision and its relation to more recent cloud computing trends....

  12. The effect of subgrid-scale models on grid-scale/subgrid-scale energy transfers in large-eddy simulation of incompressible magnetohydrodynamic turbulence

    Science.gov (United States)

    Kessar, M.; Balarac, G.; Plunian, F.

    2016-10-01

    In this work, the accuracy of various models used in large-eddy simulations (LES) of incompressible magnetohydrodynamic (MHD) turbulence is evaluated. Particular attention is devoted to the capabilities of models to reproduce the transfers between resolved grid- and subgrid-scales. The exact global balance of MHD turbulent flows is first evaluated from direct numerical simulation (DNS) database. This balance is controlled by the transfers between scales and between kinetic and magnetic energies. Two cases of forced homogeneous isotropic MHD turbulent flows are considered, with and without injecting large scale helicity. The strong helical case leads to domination of the magnetic energy due to an inverse cascade [A. Brandenburg, Astrophys. J. 550(2), 824 (2001); N. E. Haugen et al., Phys. Rev. E 70(1), 016308 (2004)]. The energy transfers predicted by various models are then compared with the transfer extracted from DNS results. This allows to discriminate models classically used for LES of MHD turbulence. In the non-helical case, the Smagorinsky-like model [M. L. Theobald et al., Phys. Plasmas 1, 3016 (1994)] and a mixed model are able to perform stable LES, but the helical case is a more demanding test and all the models lead to unstable simulations.

  13. Improvements in Climate Simulation with Modifications to the Tiedtke Convective Parameterization in the Grid-Point Atmospheric Model of IAP LASG (GAMIL)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The grid-point atmospheric model of IAP LASG (GAMIL) was developed in and has been evaluated since early 2004. Although the model shows its ability in simulating the global climate, it suffers from some problems in simulating precipitation in the tropics. These biases seem to result mainly from the treatment of the subgrid scale convection, which is parameterized with Tiedtke's massflux scheme (or the Zhang-McFarlane scheme, as an option) in the model. In order to reduce the systematic biases, several modifications were made to the Tiedtke scheme used in GAMIL, including (1) an increase in lateral convective entrainment/detrainment rate for shallow convection, (2) inclusion of a relative humidity threshold for the triggering of deep convection, and (3) a reduced efficiency for the conversion of cloud water to rainwater in the convection scheme.Two experiments, one with the original Tiedtke scheme used in GAMIL and the other with the modified scheme, were conducted to evaluate the performance of the modified scheme in this study. The results show that both the climatological mean state, such as precipitation, temperature and specific humidity, and interannual variability in the model simulation are improved with the use of this modified scheme. Results from several additional experiments show that the improvements in the model performance in different regions mainly result from either the introduction of the relative humidity threshold for triggering of the deep convection or the suppressed shallow convection due to enhanced lateral convective entrainment/detrainment rates.

  14. Collaborative learning in nursing simulation: near-peer teaching using standardized patients.

    Science.gov (United States)

    Owen, Amy M; Ward-Smith, Peggy

    2014-03-01

    Simulation in nursing education uses specific patient scenarios to provide students with hands-on learning experiences. A near-peer teaching experience, using upper-level nursing students as standardized patients, was created as an educational intervention. The premises of social cognitive theory, which include cognitive, behavioral, and environmental factors, were incorporated into this teaching activity. The upper-level students played the role of a patient, while they also practiced leadership, teaching, and mentoring of first-semester nursing students. In the scenario, the first-semester students provided care to the patient, while focusing on safety, identifying the problem, and practicing clinical decision making. Faculty were present to provide guidance and promote communication in debriefing. Near-peer teaching provided a learning opportunity for all students, facilitated teamwork, and encouraged knowledge and skills attainment. Copyright 2014, SLACK Incorporated.

  15. Urban runoff (URO) process for MODFLOW 2005: simulation of sub-grid scale urban hydrologic processes in Broward County, FL

    Science.gov (United States)

    Decker, Jeremy D.; Hughes, J.D.

    2013-01-01

    Climate change and sea-level rise could cause substantial changes in urban runoff and flooding in low-lying coast landscapes. A major challenge for local government officials and decision makers is to translate the potential global effects of climate change into actionable and cost-effective adaptation and mitigation strategies at county and municipal scales. A MODFLOW process is used to represent sub-grid scale hydrology in urban settings to help address these issues. Coupled interception, surface water, depression, and unsaturated zone storage are represented. A two-dimensional diffusive wave approximation is used to represent overland flow. Three different options for representing infiltration and recharge are presented. Additional features include structure, barrier, and culvert flow between adjacent cells, specified stage boundaries, critical flow boundaries, source/sink surface-water terms, and the bi-directional runoff to MODFLOW Surface-Water Routing process. Some abilities of the Urban RunOff (URO) process are demonstrated with a synthetic problem using four land uses and varying cell coverages. Precipitation from a hypothetical storm was applied and cell by cell surface-water depth, groundwater level, infiltration rate, and groundwater recharge rate are shown. Results indicate the URO process has the ability to produce time-varying, water-content dependent infiltration and leakage, and successfully interacts with MODFLOW.

  16. No double detonations but core carbon ignitions in high-resolution, grid-based simulations of binary white dwarf mergers

    CERN Document Server

    Fenn, D; Gawryszczak, A

    2016-01-01

    We study the violent phase of the merger of massive binary white dwarf systems. Our aim is to characterize the conditions for explosive burning to occur, and identify a possible explosion mechanism of Type Ia supernovae. The primary components of our model systems are carbon-oxygen (C/O) white dwarfs, while the secondaries are made either of C/O or of pure helium. We account for tidal effects in the initial conditions in a self-consistent way, and consider initially well-separated systems with slow inspiral rates. We study the merger evolution using an adaptive mesh refinement, reactive, Eulerian code in three dimensions, assuming symmetry across the orbital plane. We use a co-rotating reference frame to minimize the effects of numerical diffusion, and solve for self-gravity using a multi-grid approach. We find a novel detonation mechanism in C/O mergers with massive primaries. Here the detonation occurs in the primary's core and relies on the combined action of tidal heating, accretion heating, and self-heat...

  17. Global Data Grid Efforts for ATLAS

    CERN Multimedia

    Gardner, R.

    2001-01-01

    Over the past two years computational data grids have emerged as a promising new technology for large scale, data-intensive computing required by the LHC experiments, as outlined by the recent "Hoffman" review panel that addressed the LHC computing challenge. The problem essentially is to seamlessly link physicists to petabyte-scale data and computing resources, distributed worldwide, and connected by high-bandwidth research networks. Several new collaborative initiatives in Europe, the United States, and Asia have formed to address the problem. These projects are of great interest to ATLAS physicists and software developers since their objective is to offer tools that can be integrated into the core ATLAS application framework for distributed event reconstruction, Monte Carlo simulation, and data analysis, making it possible for individuals and groups of physicists to share information, data, and computing resources in new ways and at scales not previously attempted. In addition, much of the distributed IT...

  18. U.S. Army Technology Collaboration Briefing

    Science.gov (United States)

    2012-09-11

    Government) 11 Electric Power Distribution “ MicroGrid ” • TARDEC will manage the installation of a MicroGrid architecture for energy storage...Power & Mobility is collaborating with NextEnergy to deliver equipment to the Michigan National Guard to begin an initial integration of a MicroGrid ...at Camp Grayling beginning in August 2012. • The purpose of the MicroGrid demonstration is to validate the equipment which can be used as a

  19. Collaborative virtual reality based advanced cardiac life support training simulator using virtual reality principles.

    Science.gov (United States)

    Khanal, Prabal; Vankipuram, Akshay; Ashby, Aaron; Vankipuram, Mithra; Gupta, Ashish; Drumm-Gurnee, Denise; Josey, Karen; Tinker, Linda; Smith, Marshall

    2014-10-01

    Advanced Cardiac Life Support (ACLS) is a series of team-based, sequential and time constrained interventions, requiring effective communication and coordination of activities that are performed by the care provider team on a patient undergoing cardiac arrest or respiratory failure. The state-of-the-art ACLS training is conducted in a face-to-face environment under expert supervision and suffers from several drawbacks including conflicting care provider schedules and high cost of training equipment. The major objective of the study is to describe, including the design, implementation, and evaluation of a novel approach of delivering ACLS training to care providers using the proposed virtual reality simulator that can overcome the challenges and drawbacks imposed by the traditional face-to-face training method. We compare the efficacy and performance outcomes associated with traditional ACLS training with the proposed novel approach of using a virtual reality (VR) based ACLS training simulator. One hundred and forty-eight (148) ACLS certified clinicians, translating into 26 care provider teams, were enrolled for this study. Each team was randomly assigned to one of the three treatment groups: control (traditional ACLS training), persuasive (VR ACLS training with comprehensive feedback components), or minimally persuasive (VR ACLS training with limited feedback components). The teams were tested across two different ACLS procedures that vary in the degree of task complexity: ventricular fibrillation or tachycardia (VFib/VTach) and pulseless electric activity (PEA). The difference in performance between control and persuasive groups was not statistically significant (P=.37 for PEA and P=.1 for VFib/VTach). However, the difference in performance between control and minimally persuasive groups was significant (P=.05 for PEA and P=.02 for VFib/VTach). The pre-post comparison of performances of the groups showed that control (P=.017 for PEA, P=.01 for VFib/VTach) and

  20. Simulation, experimentation, and collaborative analysis of adjacent heat exchange modules in a vehicular cooling system

    Institute of Scientific and Technical Information of China (English)

    Yu-qi HUANG; Rui HUANG; Xiao-li YU; Feng LV

    2013-01-01

    A cooling system consisting of several heat exchange modules is a necessary part of an automobile,and its performance has a direct effect on a vehicle's energy consumption.Heat exchangers,such as a charged air cooler (CAC),radiator,oil cooler,or condenser have different structures and can be arranged in various orders,and each combination may produce different effects because of interactions among them.In this study,we aimed to explore the principles governing interactions among adjacent heat exchangers in a cooling system,using numerical simulation and experimental technology.3D models with different combinations were developed,compared,and analyzed comprehensively.A wind tunnel test platform was constructed to validate the computational results.We found that the heat dissipation of the modules was affected slightly by their relative position (the rules basically comply with the field synergy principle),but was independent of the modules' spacing within a certain distance range.The heat dissipation of one module could be effectively improved by restructuring,but with a penalty of higher resistance.However,the negative effect on the downstream module was much less than expected.The results indicated that the intensity of heat transfer depends not only on the average temperature difference between cold and hot mediums,but also on the temperature distribution.

  1. Axisymmetric charge-conservative electromagnetic particle simulation algorithm on unstructured grids: Application to microwave vacuum electronic devices

    Science.gov (United States)

    Na, Dong-Yeop; Omelchenko, Yuri A.; Moon, Haksu; Borges, Ben-Hur V.; Teixeira, Fernando L.

    2017-10-01

    We present a charge-conservative electromagnetic particle-in-cell (EM-PIC) algorithm optimized for the analysis of vacuum electronic devices (VEDs) with cylindrical symmetry (axisymmetry). We exploit the axisymmetry present in the device geometry, fields, and sources to reduce the dimensionality of the problem from 3D to 2D. Further, we employ 'transformation optics' principles to map the original problem in polar coordinates with metric tensor diag (1 ,ρ2 , 1) to an equivalent problem on a Cartesian metric tensor diag (1 , 1 , 1) with an effective (artificial) inhomogeneous medium introduced. The resulting problem in the meridian (ρz) plane is discretized using an unstructured 2D mesh considering TEϕ-polarized fields. Electromagnetic field and source (node-based charges and edge-based currents) variables are expressed as differential forms of various degrees, and discretized using Whitney forms. Using leapfrog time integration, we obtain a mixed E - B finite-element time-domain scheme for the full-discrete Maxwell's equations. We achieve a local and explicit time update for the field equations by employing the sparse approximate inverse (SPAI) algorithm. Interpolating field values to particles' positions for solving Newton-Lorentz equations of motion is also done via Whitney forms. Particles are advanced using the Boris algorithm with relativistic correction. A recently introduced charge-conserving scatter scheme tailored for 2D unstructured grids is used in the scatter step. The algorithm is validated considering cylindrical cavity and space-charge-limited cylindrical diode problems. We use the algorithm to investigate the physical performance of VEDs designed to harness particle bunching effects arising from the coherent (resonance) Cerenkov electron beam interactions within micro-machined slow wave structures.

  2. Mediterranean Overflow Water (MOW) Simulation Using a Coupled Multiple-Grid Mediterranean Sea/North Atlantic Ocean Model

    Science.gov (United States)

    2008-07-22

    region where meddies are spawned. They further relaxed their model toward clima - tology using spatially varying timescale, with the fastest (50 d...two jets of the present simulations, but with the second one very weak in clima - tology. In Figure 4b of DR05 there appears to be one jet defined by

  3. SIMULATING THE COMMON ENVELOPE PHASE OF A RED GIANT USING SMOOTHED-PARTICLE HYDRODYNAMICS AND UNIFORM-GRID CODES

    Energy Technology Data Exchange (ETDEWEB)

    Passy, Jean-Claude; Mac Low, Mordecai-Mark [Department of Astrophysics, American Museum of Natural History, New York, NY (United States); De Marco, Orsola [Department of Physics and Astronomy, Macquarie University, Sydney, NSW (Australia); Fryer, Chris L.; Diehl, Steven; Rockefeller, Gabriel [Computational Computer Science Division, Los Alamos National Laboratory, Los Alamos, NM (United States); Herwig, Falk [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Oishi, Jeffrey S. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Palo Alto, CA (United States); Bryan, Greg L. [Department of Astronomy, Columbia University, New York, NY (United States)

    2012-01-01

    We use three-dimensional hydrodynamical simulations to study the rapid infall phase of the common envelope (CE) interaction of a red giant branch star of mass equal to 0.88 M{sub Sun} and a companion star of mass ranging from 0.9 down to 0.1 M{sub Sun }. We first compare the results obtained using two different numerical techniques with different resolutions, and find very good agreement overall. We then compare the outcomes of those simulations with observed systems thought to have gone through a CE. The simulations fail to reproduce those systems in the sense that most of the envelope of the donor remains bound at the end of the simulations and the final orbital separations between the donor's remnant and the companion, ranging from 26.8 down to 5.9 R{sub Sun }, are larger than the ones observed. We suggest that this discrepancy vouches for recombination playing an essential role in the ejection of the envelope and/or significant shrinkage of the orbit happening in the subsequent phase.

  4. Developing educator competency to facilitate the use of simulation-based learning in nurse education. A collaborative project (NESTLED) supported by the EU Lifelong Learning Programme

    DEFF Research Database (Denmark)

    Hartvigsen, Tina

    2014-01-01

    of the collaboration first met. Since, through a series of face-to-face and virtual meetings, a once aspirational programme of work related to nurse educateducator competency in simulation-based learning has become a reality. The present collaboration on the NESTLED project emerged from a literature review...... learning and it has been incorporated as a teaching and learning strategy into many undergraduate nursing programmes. This is unsurprising giving the growing perception that simulation-based learning is the solution to many of the challenges associated with producing practitioners who are able to function...... project is to produce evidence based training model for teachers in nursing education using simulated learning in their teaching. The project begun with a ‘kick-off’ meeting in 9/2013 and is split into six different work packages. The project will continue until 12/2015. All partners are working...

  5. Modeling and Simulation of Transient Fault Response at Lillgrund Wind Farm when Subjected to Faults in the Connecting 130 kV Grid

    Energy Technology Data Exchange (ETDEWEB)

    Eliasson, Anders; Isabegovic, Emir

    2009-07-01

    The purpose of this thesis was to investigate what type of faults in the connecting grid should be dimensioning for future wind farms. An investigation of over and under voltages at the main transformer and the turbines inside Lillgrund wind farm was the main goal. The results will be used in the planning stage of future wind farms when performing insulation coordination and determining the protection settings. A model of the Lillgrund wind farm and a part of the connecting 130 kV grid were built in PSCAD/EMTDC. The farm consists of 48 Siemens SWT-2.3-93 2.3 MW wind turbines with full power converters. The turbines were modeled as controllable current sources providing a constant active power output up to the current limit of 1.4 pu. The transmission lines and cables were modeled as frequency dependent (phase) models. The load flows and bus voltages were verified towards a PSS/E model and the transient response was verified towards measuring data from two faults, a line to line fault in the vicinity of Barsebaeck (BBK) and a single line-to-ground fault close to Bunkeflo (BFO) substation. For the simulation, three phase to ground, single line to ground and line to line faults were applied at different locations in the connecting grid and the phase to ground voltages at different buses in the connecting grid and at turbines were studied. These faults were applied for different configurations of the farm. For single line to ground faults, the highest over voltage on a turbine was 1.22 pu (32.87 kV) due to clearing of a fault at BFO (the PCC). For line to line faults, the highest over voltage on a turbine was 1.59 pu (42.83 kV) at the beginning of a fault at KGE one bus away from BFO. Both these cases were when all radials were connected and the turbines ran at full power. The highest over voltage observed at Lillgrund was 1.65 pu (44.45 kV). This over voltage was caused by a three phase to ground fault applied at KGE and occurred at the beginning of the fault and when

  6. HIRENASD NLR grid

    Data.gov (United States)

    National Aeronautics and Space Administration — Structured multiblock grid of HIRENASD wing with medium grid density, about 10 mill grid points, 9.5 mill cells. Starting from coarse AIAA AEPW structured grid,...

  7. Collaboration Services: Enabling Chat in Disadvantaged Grids

    Science.gov (United States)

    2014-06-01

    We implement the optional support for dynamic multicast groups as well as the mandatory static groups. • We implement support for IPv6 when using...Here, only IPv4 is supported, as differences relating to IPv4 and IPv6 addressing meant that this functionality was not easily extended to use IPv6 ...recent years there has been an increasing interest in IPv6 also for defense use (see e.g., the recent CONSiS experiment [17] where IPv6 was employed

  8. Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3

    Science.gov (United States)

    Westermann, S.; Langer, M.; Boike, J.; Heikenfeld, M.; Peter, M.; Etzelmüller, B.; Krinner, G.

    2016-02-01

    Thawing of permafrost in a warming climate is governed by a complex interplay of different processes of which only conductive heat transfer is taken into account in most model studies. However, observations in many permafrost landscapes demonstrate that lateral and vertical movement of water can have a pronounced influence on the thaw trajectories, creating distinct landforms, such as thermokarst ponds and lakes, even in areas where permafrost is otherwise thermally stable. Novel process parameterizations are required to include such phenomena in future projections of permafrost thaw and subsequent climatic-triggered feedbacks. In this study, we present a new land-surface scheme designed for permafrost applications, CryoGrid 3, which constitutes a flexible platform to explore new parameterizations for a range of permafrost processes. We document the model physics and employed parameterizations for the basis module CryoGrid 3, and compare model results with in situ observations of surface energy balance, surface temperatures, and ground thermal regime from the Samoylov permafrost observatory in NE Siberia. The comparison suggests that CryoGrid 3 can not only model the evolution of the ground thermal regime in the last decade, but also consistently reproduce the chain of energy transfer processes from the atmosphere to the ground. In addition, we demonstrate a simple 1-D parameterization for thaw processes in permafrost areas rich in ground ice, which can phenomenologically reproduce both formation of thermokarst ponds and subsidence of the ground following thawing of ice-rich subsurface layers. Long-term simulation from 1901 to 2100 driven by reanalysis data and climate model output demonstrate that the hydrological regime can both accelerate and delay permafrost thawing. If meltwater from thawed ice-rich layers can drain, the ground subsides, as well as the formation of a talik, are delayed. If the meltwater pools at the surface, a pond is formed that enhances heat

  9. Grid reliability

    CERN Document Server

    Saiz, P; Rocha, R; Andreeva, J

    2007-01-01

    We are offering a system to track the efficiency of different components of the GRID. We can study the performance of both the WMS and the data transfers At the moment, we have set different parts of the system for ALICE, ATLAS, CMS and LHCb. None of the components that we have developed are VO specific, therefore it would be very easy to deploy them for any other VO. Our main goal is basically to improve the reliability of the GRID. The main idea is to discover as soon as possible the different problems that have happened, and inform the responsible. Since we study the jobs and transfers issued by real users, we see the same problems that users see. As a matter of fact, we see even more problems than the end user does, since we are also interested in following up the errors that GRID components can overcome by themselves (like for instance, in case of a job failure, resubmitting the job to a different site). This kind of information is very useful to site and VO administrators. They can find out the efficien...

  10. 并网光伏电站的PSASP/UPI仿真建模及分析%PSASP/UPI Simulation Modelling and Analysis of the PV Power Station in Grid Integration

    Institute of Scientific and Technical Information of China (English)

    孙文涛; 刘涤尘; 赵洁; 董飞飞; 陈恩泽; 曾正

    2014-01-01

    针对光伏电站和电网之间的交互影响,研究了适用于电网暂态分析的光伏电站模型,建立了含光伏阵列、逆变器、滤波器及控制保护系统的并网光伏电站暂态模型,并应用 Matlab实时工具包模块和 VC++语言生成了可被PSASP调用的自定义模型,仿真研究了并网光伏电站出力变化对电网影响及电网故障对以不同方式接入电网的并网光伏电站的影响。结果表明,该模型可用于光伏电站与电网的联合仿真。大规模光伏电源集中接入会引起电网电压波动;电网故障可能触发光伏电站脱网,使故障扩大;且在负荷母线集中接入方式下对电网电压及暂态稳定的影响更大。%To study the interaction between the PV power plant and power grid, grid-connected photovoltaic system( GCPS) transient model is built. The transient model includes photovoltaic array, inverter, filter, as well as control and protection system. The custom model that can be called by PSASP is generated by RTW ( Real-Time Workshop, RTW) modules in Matlab and VC+ +. In addi-tion, the variation of GCPS's power output and its impact on power grid are researched, and the influence of power grid fault on GCPS with different connection modes is also analyzed. The simulation results show that the model can be used for joint simulation between the GCPS and the power grid. Large-scale photovoltaic power connected to power grid will cause the grid voltage fluctuation, The power grid fault may lead to disconnection between the GCPS and the grid, resulting in the fault to expand. It takes the greater adverse impact to the voltage and transient stability of power grid when the GCPS is connected to the load bus.

  11. Finite Volume schemes on unstructured grids for non-local models: Application to the simulation of heat transport in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Goudon, Thierry, E-mail: thierry.goudon@inria.fr [Team COFFEE, INRIA Sophia Antipolis Mediterranee (France); Labo. J.A. Dieudonne CNRS and Univ. Nice-Sophia Antipolis (UMR 7351), Parc Valrose, 06108 Nice cedex 02 (France); Parisot, Martin, E-mail: martin.parisot@gmail.com [Project-Team SIMPAF, INRIA Lille Nord Europe, Park Plazza, 40 avenue Halley, F-59650 Villeneuve d' Ascq cedex (France)

    2012-10-15

    In the so-called Spitzer-Haerm regime, equations of plasma physics reduce to a nonlinear parabolic equation for the electronic temperature. Coming back to the derivation of this limiting equation through hydrodynamic regime arguments, one is led to construct a hierarchy of models where the heat fluxes are defined through a non-local relation which can be reinterpreted as well by introducing coupled diffusion equations. We address the question of designing numerical methods to simulate these equations. The basic requirement for the scheme is to be asymptotically consistent with the Spitzer-Haerm regime. Furthermore, the constraints of physically realistic simulations make the use of unstructured meshes unavoidable. We develop a Finite Volume scheme, based on Vertex-Based discretization, which reaches these objectives. We discuss on numerical grounds the efficiency of the method, and the ability of the generalized models in capturing relevant phenomena missed by the asymptotic problem.

  12. Toward a Grid Work flow Formal Composition

    Energy Technology Data Exchange (ETDEWEB)

    Hlaoui, Y. B.; BenAyed, L. J.

    2007-07-01

    This paper exposes a new approach for the composition of grid work flow models. This approach proposes an abstract syntax for the UML Activity Diagrams (UML-AD) and a formal foundation for grid work flow composition in form of a work flow algebra based on UML-AD. This composition fulfils the need for collaborative model development particularly the specification and the reduction of the complexity of grid work flow model verification. This complexity has arisen with the increase in scale of grid work flow applications such as science and e-business applications since large amounts of computational resources are required and multiple parties could be involved in the development process and in the use of grid work flows. Furthermore, the proposed algebra allows the definition of work flow views which are useful to limit the access to predefined users in order to ensure the security of grid work flow applications. (Author)

  13. Autonomous tools for Grid management, monitoring and optimization

    CERN Document Server

    Wislicki, Wojciech

    2007-01-01

    We outline design and lines of development of autonomous tools for the computing Grid management, monitoring and optimization. The management is proposed to be based on the notion of utility. Grid optimization is considered to be application-oriented. A generic Grid simulator is proposed as an optimization tool for Grid structure and functionality.

  14. Collaboration 'Engineerability'

    NARCIS (Netherlands)

    Kolfschoten, Gwendolyn L.; de Vreede, Gert-Jan; Briggs, Robert O.; Sol, Henk G.

    2010-01-01

    Collaboration Engineering is an approach to create sustained collaboration support by designing collaborative work practices for high-value recurring tasks, and transferring those designs to practitioners to execute for themselves without ongoing support from collaboration professionals. A key assum

  15. Grid-Voltage-Feedforward Active Damping for Grid-Connected Inverter with LCL Filter

    DEFF Research Database (Denmark)

    Lu, Minghui; Wang, Xiongfei; Blaabjerg, Frede;

    2016-01-01

    For the grid-connected voltage source inverters, the feedforward scheme of grid voltage is commonly adopted to mitigate the current distortion caused by grid background voltages harmonics. This paper investigates the grid-voltage-feedforward active damping for grid connected inverter with LCL fil...... for Phase Locked Loop (PLL). Simulation and experiment results are provided for verifying the theoretical analyses....... filter. It reveals that proportional feedforward control can not only fulfill the mitigation of grid disturbance, but also offer damping effects on the LCL filter resonance. Digital delays are intrinsic to digital controlled inverters; with these delays, the feedforward control can be equivalent...

  16. Coarse grid shallow water simulations of rainfall-runoff in small catchments with modified friction law to account for unresolved microtopography

    Science.gov (United States)

    Özgen, Ilhan; Serrano-Taslim, Miguel; Zhao, Jiaheng; Liang, Dongfang; Hinkelmann, Reinhard

    2016-04-01

    In recent years, the fully dynamic shallow water equations have been successfully used to simulate rainfall-runoff in natural catchments. Hereby, the hydrodynamics of the surface runoff is greatly influenced by local topographical features. Thus, it is desirable to use high-resolution models which resolve the topography of the study area sufficiently. However, high-resolution simulations across catchment scales are often unfeasible due to finite computer resources. In this contribution, the shallow water equations are solved on a coarse resolution, leaving significant topographical features unresolved. The coarsened grid size leads to a smaller cell number and therefore reduces computational cost. The influence of the topography is accounted for with an artificial friction source term which is dependent on the inundation ratio, i.e. the ratio of water depth to roughness height, the slope and two additional parameters, namely a dimensionless friction coefficient and a geometric conveyance parameter. Subgrid scale information is used to determine these parameters. The friction approach is applied in two different ways: (1) a global average roughness height for the entire catchment is calculated and used as input, (2) the roughness height is calculated individually in each cell which introduces additional heterogeneity to the model. In two test cases, the individual roughness height-based approach is compared to results of the global roughness height-based approach and to igh-resolution model results. The comparison shows slight improvement in the results if the roughness height is assigned individually, however overall the improvement is negligible. Both models enable to run the simulations about three orders of magnitude faster than the high-resolution model.

  17. Architectural Aspects of Grid Computing and its Global Prospects for E-Science Community

    Science.gov (United States)

    Ahmad, Mushtaq

    2008-05-01

    The paper reviews the imminent Architectural Aspects of Grid Computing for e-Science community for scientific research and business/commercial collaboration beyond physical boundaries. Grid Computing provides all the needed facilities; hardware, software, communication interfaces, high speed internet, safe authentication and secure environment for collaboration of research projects around the globe. It provides highly fast compute engine for those scientific and engineering research projects and business/commercial applications which are heavily compute intensive and/or require humongous amounts of data. It also makes possible the use of very advanced methodologies, simulation models, expert systems and treasure of knowledge available around the globe under the umbrella of knowledge sharing. Thus it makes possible one of the dreams of global village for the benefit of e-Science community across the globe.

  18. A New Heuristic Providing an Effective Initial Solution for a Simulated Annealing approach to Energy Resource Scheduling in Smart Grids

    DEFF Research Database (Denmark)

    Sousa, Tiago M; Morais, Hugo; Castro, R.

    2014-01-01

    to be used in the energy resource scheduling methodology based on simulated annealing previously developed by the authors. The case study considers two scenarios with 1000 and 2000 electric vehicles connected in a distribution network. The proposed heuristics are compared with a deterministic approach......An intensive use of dispersed energy resources is expected for future power systems, including distributed generation, especially based on renewable sources, and electric vehicles. The system operation methods and tool must be adapted to the increased complexity, especially the optimal resource...... scheduling problem. Therefore, the use of metaheuristics is required to obtain good solutions in a reasonable amount of time. This paper proposes two new heuristics, called naive electric vehicles charge and discharge allocation and generation tournament based on cost, developed to obtain an initial solution...

  19. Modeling, Control, and Simulation of a Solar Hydrogen/Fuel Cell Hybrid Energy System for Grid-Connected Applications

    Directory of Open Access Journals (Sweden)

    Tourkia Lajnef

    2013-01-01

    Full Text Available Different energy sources and converters need to be integrated with each other for extended usage of alternative energy, in order to meet sustained load demands during various weather conditions. The objective of this paper is to associate photovoltaic generators, fuel cells, and electrolysers. Here, to sustain the power demand and solve the energy storage problem, electrical energy can be stored in the form of hydrogen. By using an electrolyser, hydrogen can be generated and stored for future use. The hydrogen produced by the electrolyser using PV power is used in the FC system and acts as an energy buffer. Thus, the effects of reduction and even the absence of the available power from the PV system can be easily tackled. Modeling and simulations are performed using MATLAB/Simulink and SimPowerSystems packages and results are presented to verify the effectiveness of the proposed system.

  20. Experiences of Engineering Grid-Based Medical Software

    CERN Document Server

    Estrella, F; McClatchey, R; Odeh, M; Rogulin, D; Solomonides, T

    2007-01-01

    Objectives: Grid-based technologies are emerging as potential solutions for managing and collaborating distributed resources in the biomedical domain. Few examples exist, however, of successful implementations of Grid-enabled medical systems and even fewer have been deployed for evaluation in practice. The objective of this paper is to evaluate the use in clinical practice of a Grid-based imaging prototype and to establish directions for engineering future medical Grid developments and their subsequent deployment. Method: The MammoGrid project has deployed a prototype system for clinicians using the Grid as its information infrastructure. To assist in the specification of the system requirements (and for the first time in healthgrid applications), use-case modelling has been carried out in close collaboration with clinicians and radiologists who had no prior experience of this modelling technique. A critical qualitative and, where possible, quantitative analysis of the MammoGrid prototype is presented leading...

  1. Parallelization of TWOPORFLOW, a Cartesian Grid based Two-phase Porous Media Code for Transient Thermo-hydraulic Simulations

    Science.gov (United States)

    Trost, Nico; Jiménez, Javier; Imke, Uwe; Sanchez, Victor

    2014-06-01

    TWOPORFLOW is a thermo-hydraulic code based on a porous media approach to simulate single- and two-phase flow including boiling. It is under development at the Institute for Neutron Physics and Reactor Technology (INR) at KIT. The code features a 3D transient solution of the mass, momentum and energy conservation equations for two inter-penetrating fluids with a semi-implicit continuous Eulerian type solver. The application domain of TWOPORFLOW includes the flow in standard porous media and in structured porous media such as micro-channels and cores of nuclear power plants. In the latter case, the fluid domain is coupled to a fuel rod model, describing the heat flow inside the solid structure. In this work, detailed profiling tools have been utilized to determine the optimization potential of TWOPORFLOW. As a result, bottle-necks were identified and reduced in the most feasible way, leading for instance to an optimization of the water-steam property computation. Furthermore, an OpenMP implementation addressing the routines in charge of inter-phase momentum-, energy- and mass-coupling delivered good performance together with a high scalability on shared memory architectures. In contrast to that, the approach for distributed memory systems was to solve sub-problems resulting by the decomposition of the initial Cartesian geometry. Thread communication for the sub-problem boundary updates was accomplished by the Message Passing Interface (MPI) standard.

  2. Adaptive workflow scheduling in grid computing based on dynamic resource availability

    Directory of Open Access Journals (Sweden)

    Ritu Garg

    2015-06-01

    Full Text Available Grid computing enables large-scale resource sharing and collaboration for solving advanced science and engineering applications. Central to the grid computing is the scheduling of application tasks to the resources. Various strategies have been proposed, including static and dynamic strategies. The former schedules the tasks to resources before the actual execution time and later schedules them at the time of execution. Static scheduling performs better but it is not suitable for dynamic grid environment. The lack of dedicated resources and variations in their availability at run time has made this scheduling a great challenge. In this study, we proposed the adaptive approach to schedule workflow tasks (dependent tasks to the dynamic grid resources based on rescheduling method. It deals with the heterogeneous dynamic grid environment, where the availability of computing nodes and links bandwidth fluctuations are inevitable due to existence of local load or load by other users. The proposed adaptive workflow scheduling (AWS approach involves initial static scheduling, resource monitoring and rescheduling with the aim to achieve the minimum execution time for workflow application. The approach differs from other techniques in literature as it considers the changes in resources (hosts and links availability and considers the impact of existing load over the grid resources. The simulation results using randomly generated task graphs and task graphs corresponding to real world problems (GE and FFT demonstrates that the proposed algorithm is able to deal with fluctuations of resource availability and provides overall optimal performance.

  3. The LHC Computing Grid in the starting blocks

    CERN Multimedia

    Danielle Amy Venton

    2010-01-01

    As the Large Hadron Collider ramps up operations and breaks world records, it is an exciting time for everyone at CERN. To get the computing perspective, the Bulletin this week caught up with Ian Bird, leader of the Worldwide LHC Computing Grid (WLCG). He is confident that everything is ready for the first data.   The metallic globe illustrating the Worldwide LHC Computing GRID (WLCG) in the CERN Computing Centre. The Worldwide LHC Computing Grid (WLCG) collaboration has been in place since 2001 and for the past several years it has continually run the workloads for the experiments as part of their preparations for LHC data taking. So far, the numerous and massive simulations of the full chain of reconstruction and analysis software could only be carried out using Monte Carlo simulated data. Now, for the first time, the system is starting to work with real data and with many simultaneous users accessing them from all around the world. “During the 2009 large-scale computing challenge (...

  4. Features in simulation of crystal growth using the hyperbolic PFC equation and the dependence of the numerical solution on the parameters of the computational grid

    Energy Technology Data Exchange (ETDEWEB)

    Starodumov, Ilya [Laboratory of Multi-Scale Mathematical Modeling, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kropotin, Nikolai [AO NPO MKM, Ilfata Zakirova st. 24, 426000 Izhevsk (Russian Federation)

    2016-08-10

    We investigate the three-dimensional mathematical model of crystal growth called PFC (Phase Field Crystal) in a hyperbolic modification. This model is also called the modified model PFC (originally PFC model is formulated in parabolic form) and allows to describe both slow and rapid crystallization processes on atomic length scales and on diffusive time scales. Modified PFC model is described by the differential equation in partial derivatives of the sixth order in space and second order in time. The solution of this equation is possible only by numerical methods. Previously, authors created the software package for the solution of the Phase Field Crystal problem, based on the method of isogeometric analysis (IGA) and PetIGA program library. During further investigation it was found that the quality of the solution can strongly depends on the discretization parameters of a numerical method. In this report, we show the features that should be taken into account during constructing the computational grid for the numerical simulation.

  5. QUICK ASSESSMENT METHODOLOGY FOR RELIABILITY OF SOLDER JOINTS IN BALL GRID ARRAY (BGA)ASSEMBLY--PART Ⅱ: RELIABILITY EXPERIMENT AND NUMERICAL SIMULATION

    Institute of Scientific and Technical Information of China (English)

    史训清; John HL Pang; 杨前进; 王志平; 聂景旭

    2002-01-01

    In the present study, a facility, i.e., a mechanical deflection system(MDS), was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly. It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days, but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests.Based on the MDS and ATC reliability experiments, the acceleration factors (AF)were obtained for different reliability testing conditions. Furthermore, by using the creep constitutive relation and fatigue life model developed in part I, a numerical approach was established for the purpose of virtual life prediction of solder joints.The simulation results were found to be in good agreement with the test results from the MDS. As a result, a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.

  6. Numerical simulation of groundwater level in a fractured porous medium and sensitivity analysis of the hydrodynamic parameters using grid computing: application of the plain of Gondo (Burkina Faso

    Directory of Open Access Journals (Sweden)

    Wenddabo Olivier Sawadogo

    2012-01-01

    Full Text Available The use of mathematical modeling as a tool for decision support is not common in Africa in solving development problems. In this article we talk about the numerical simulation of groundwater level of the plain of Gondo (Burkina Faso and the sensitivity analysis of the hydrodynamic parameters. The domain has fractures which have hydraulic coefficients lower than those of the rock. Our contribution is to bring brief replies to the real problem posed in the thesis of Mr. KOUSSOUBE [1]. Namely that what causes the appearance of the piezometric level observed and impact of surface water on the piezometry. The mathematical model of the flow was solved by programming the finite element method on FreeFem++[2]. A local refinement of the mesh at fracture was used. We then conduct a sensitivity analysis to see which hydrodynamic parameters influences much of the solution. The method used for the sensitivity analysis is based on the calculation of the gradient by the adjoint equation and requires great computational power. To remedy this, we used a technique of distributed computing and we launched our application to the Moroccan grid (magrid. This allowed us to reduce the computation time. The results allowed to highlight the role of fractures and contributions of surface water on the evolution of the piezometric level of the plain of Gondo and identified the parameters that greatly influence the piezometric level.

  7. Features in simulation of crystal growth using the hyperbolic PFC equation and the dependence of the numerical solution on the parameters of the computational grid

    Science.gov (United States)

    Starodumov, Ilya; Kropotin, Nikolai

    2016-08-01

    We investigate the three-dimensional mathematical model of crystal growth called PFC (Phase Field Crystal) in a hyperbolic modification. This model is also called the modified model PFC (originally PFC model is formulated in parabolic form) and allows to describe both slow and rapid crystallization processes on atomic length scales and on diffusive time scales. Modified PFC model is described by the differential equation in partial derivatives of the sixth order in space and second order in time. The solution of this equation is possible only by numerical methods. Previously, authors created the software package for the solution of the Phase Field Crystal problem, based on the method of isogeometric analysis (IGA) and PetIGA program library. During further investigation it was found that the quality of the solution can strongly depends on the discretization parameters of a numerical method. In this report, we show the features that should be taken into account during constructing the computational grid for the numerical simulation.

  8. Modeling and Simulation of Small Off-Grid Wind Power System%离网小型风力发电系统的建模与仿真

    Institute of Scientific and Technical Information of China (English)

    唐江丰; 韩春成; 王萍; 王立地

    2012-01-01

    In this paper, the model of small off-grid wind power generation system is established by Matlab/simulink and the wind power generation system is developed by analyzing the wind speed and other parts of the system. The simulation results show that the system can run stably at various wind speeds with support of lead -acid batteries, and the voltage and current waveforms at the load end can meet the necessary requirements of customers.%在Matlab/simulink环境下建立了离网小型风力发电系统仿真模型,通过对风速和系统各部分进行理论分析,实现整体模型的搭建.仿真结果表明,在铅酸蓄电池作用下,系统能在变化风速下持续稳定运行,负载端电压符合用户要求.

  9. Evaluation of the Impacts of Assimilating the TAMDAR Data on 12/4 km Grid WRF-Based RTFDDA Simulations over the CONUS

    Directory of Open Access Journals (Sweden)

    Yongxin Zhang

    2016-01-01

    Full Text Available An analysis of the impacts of assimilating the Tropospheric Airborne Meteorological Data Report (TAMDAR data with the Weather Research and Forecasting- (WRF- real-time four-dimensional data assimilation (RTFDDA and forecasting system over the Contiguous US (CONUS is presented. The impacts of the horizontal resolution increase from 12 km to 4 km on the WRF-RTFDDA simulations are also examined in conjunction with the TAMDAR data impacts. The assimilation of the TAMDAR data reduces the root mean squared error of the moisture field predictions and increases the correlation between the predictions and the observations for both domains with 12 km and 4 km grid spacings. The TAMDAR data reduce the model dry biases in the middle and lower levels by adding moisture at those levels. Assimilating the TAMDAR data improves temperature predictions at middle to high levels and wind speed predictions at all levels especially for the 12 km domain. Increasing the horizontal resolution from 12 km to 4 km results in significantly larger impacts on surface variables than assimilating the TAMDAR data.

  10. Final Report for Collaborative Project: Sensitivity of Atmospheric Parametric Formulations to Regional Mesh Refinement in Global Climate Simulations Using CESM-HOMME

    Energy Technology Data Exchange (ETDEWEB)

    Neale, Richard B. [University Corporation For Atmospheric Research, Boulder, CO (United States)

    2015-12-01

    In this project we analyze climate simulations using the Community Earth System Model (CESM) in order to determine the modeled response and sensitivity to horizontal resolution. Simple aqua-planet configurations were used to provide a clean comparison of the response to resolution in CESM. This enables us to easily examine all aspects of the model sensitivity to resolution including mean quantities, variability and physical parameterization tendencies: the chief reflection of resolution sensitivity. An extension to the global resolution sensitivity study is the examination of regional grid refinement where resolution changes are prescribed in a single global simulation. We examine the relevance of the global resolution sensitivity results as applied to these regional refinement simulations. In particular we examine how variations in the grid resolution, centered on different parts of the globe, lead to differences in the parameterized response and the potential to generate residual circulations as a result. Given the potential to generate this resolution sensitivity we examine simple modifications to the parameterized physics that are able to moderate any residual circulations. Finally, we transfer the framework to the standard AMIP configuration to examine the resolution sensitivity in the presence of compounding effects such as land-sea distributions, orography and seasonal variation.

  11. Application Note: Power Grid Modeling With Xyce.

    Energy Technology Data Exchange (ETDEWEB)

    Sholander, Peter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-06-01

    This application note describes how to model steady-state power flows and transient events in electric power grids with the SPICE-compatible Xyce TM Parallel Electronic Simulator developed at Sandia National Labs. This application notes provides a brief tutorial on the basic devices (branches, bus shunts, transformers and generators) found in power grids. The focus is on the features supported and assumptions made by the Xyce models for power grid elements. It then provides a detailed explanation, including working Xyce netlists, for simulating some simple power grid examples such as the IEEE 14-bus test case.

  12. 5kW光伏并网发电系统及其仿真研究%Simulation research on 5kW photovoltaic grid-connection system

    Institute of Scientific and Technical Information of China (English)

    袁晓玲; 范发靖; 周素梅

    2011-01-01

    With the rapid development of new energy resources,more and more renewable energy was feed into electrical grid by inverter.Using MATLAB/Simulink tool box,a simulation model of 5 kW photovoltaic grid-connection with PV array output,Boost circuit,inverter,controller and electrical grid is constructed.Characteristics of PV grid-connection system based on the simulation model are researched.Adopting variable structure fuzzy PID controller,the 5 kW PV system achieves MPPT.Sampling grid voltage as reference voltage of inverter and using hysteresis comparison method,the system output current has the same phase and frequency with grid voltage and has unit power factor.Simulation results reveal the 5 kW PV system has the MPPT and can be connected to grid safety.The simulation model has reference value for practical PV system design.%随着新能源发电的迅速发展,越来越多的可再生能源被转化为电能并通过并网逆变器输送到电网。利用MATLAB仿真工具箱建立了由光伏阵列输出、Boost升压电路、逆变器、控制器、电网等组成的5 kW光伏并网发电系统的仿真模型,研究了光伏并网系统的特性。采用变结构模糊PID控制器实现5 kW光伏发电系统的MPPT;采样电网电压作为逆变器电流的参考信号,利用滞环比较法控制逆变器,实现系统输出电流与电网电压同频同相,功率因素近似为1。仿真结果表明,系统较好地实现了光伏发电系统的MPPT及安全并网,对实际光伏并网系统的设计有参考意义。

  13. The Open Science Grid

    Energy Technology Data Exchange (ETDEWEB)

    Pordes, Ruth; /Fermilab; Kramer, Bill; Olson, Doug; / /LBL, Berkeley; Livny, Miron; Roy, Alain; /Wisconsin U., Madison; Avery, Paul; /Florida U.; Blackburn, Kent; /Caltech; Wenaus, Torre; /Brookhaven; Wurthwein, Frank; /UC, San Diego; Gardner, Rob; Wilde, Mike; /Chicago U. /Indiana U.

    2007-06-01

    The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. OSG provides support for and evolution of the infrastructure through activities that cover operations, security, software, troubleshooting, addition of new capabilities, and support for existing and engagement with new communities. The OSG SciDAC-2 project provides specific activities to manage and evolve the distributed infrastructure and support its use. The innovative aspects of the project are the maintenance and performance of a collaborative (shared & common) petascale national facility over tens of autonomous computing sites, for many hundreds of users, transferring terabytes of data a day, executing tens of thousands of jobs a day, and providing robust and usable resources for scientific groups of all types and sizes. More information can be found at the OSG web site: www.opensciencegrid.org.

  14. The Open Science Grid

    CERN Document Server

    Pordes, Ruth; Olson, Doug; Livny, Miron; Roy, Alain; Avery, Paul; Blackburn, Kent; Wenaus, Torre; Wuerthwein, Frank K.; Gardner, Rob; Wilde, Mike; Blatecky, Alan; McGee, John; Quick, Rob

    2007-01-01

    The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. OSG provides support for and evolution of the infrastructure through activities that cover operations, security, software, troubleshooting, addition of new capabilities, and support for existing and engagement with new communities. The OSG SciDAC-2 project provides specific activities to manage and evolve the distributed infrastructure and support it's use. The innovative aspects of the project are the maintenance and performance of a collaborative (shared & common) petascale national facility over tens of autonomous computing sites, for many hundreds of users, transferring terabytes of data a day, executing tens of thousands of jobs a day, and providing robust and usable resources for scientific groups of all types and sizes. More information can be found at the OSG web site: www.opensciencegrid.org.

  15. The open science grid

    Energy Technology Data Exchange (ETDEWEB)

    Pordes, Ruth [Fermi National Accelerator Laboratory (United States); Petravick, Don [Fermi National Accelerator Laboratory (United States); Kramer, Bill [Lawrence Berkeley National Laboratory (United States); Olson, Doug [Lawrence Berkeley National Laboratory (United States); Livny, Miron [University of Wisconsin, Madison (United States); Roy, Alain [University of Wisconsin, Madison (United States); Avery, Paul [University of Florida (United States); Blackburn, Kent [California Institute of Technology (United States); Wenaus, Torre [Brookhaven National Laboratory (United States); Wuerthwein, Frank [University of California, San Diego (United States); Foster, Ian [University of Chicago (United States); Gardner, Rob [University of Chicago (United States); Wilde, Mike [University of Chicago (United States); Blatecky, Alan [Renaissance Computing Institute (United States); McGee, John [Renaissance Computing Institute (United States); Quick, Rob [Indiana University (United States)

    2007-07-15

    The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. OSG provides support for and evolution of the infrastructure through activities that cover operations, security, software, troubleshooting, addition of new capabilities, and support for existing and engagement with new communities. The OSG SciDAC-2 project provides specific activities to manage and evolve the distributed infrastructure and support it's use. The innovative aspects of the project are the maintenance and performance of a collaborative (shared and common) petascale national facility over tens of autonomous computing sites, for many hundreds of users, transferring terabytes of data a day, executing tens of thousands of jobs a day, and providing robust and usable resources for scientific groups of all types and sizes. More information can be found at the OSG web site: www.opensciencegrid.org.

  16. Grid Added Value to Address Malaria

    CERN Document Server

    Breton, V; Hofmann, M

    2008-01-01

    Through this paper, we call for a distributed, internet-based collaboration to address one of the worst plagues of our present world, malaria. The spirit is a non-proprietary peer-production of information-embedding goods. And we propose to use the grid technology to enable such a world wide "open source" like collaboration. The first step towards this vision has been achieved during the summer on the EGEE grid infrastructure where 46 million ligands were docked for a total amount of 80 CPU years in 6 weeks in the quest for new drugs.

  17. Energy Efficient Resource Management in Mobile Grid

    Directory of Open Access Journals (Sweden)

    Chunlin Li

    2010-01-01

    Full Text Available Energy efficient computing has recently become hot research area. Many works have been carried out on conserving energy, but considering energy efficiency in grid computing is few. This paper proposes energy efficient resource management in mobile grid. The objective of energy efficient resource management in mobile grid is to maximize the utility of the mobile grid which is denoted as the sum of grid application utility. The utility function models benefits of application and system. By using nonlinear optimization theory, energy efficient resource management in mobile grid can be formulated as multi objective optimization problem. In order to derive a distributed algorithm to solve global optimization problem in mobile grid, we decompose the problem into the sub problems. The proposed energy efficient resource management algorithm decomposes the optimization problem via iterative method. To test the performance of the proposed algorithm, the simulations are conducted to compare proposed energy efficient resource management algorithm with other energy aware scheduling algorithm.

  18. 基于共生仿真的巡航导弹协同作战研究%Research on symbiotic simulation based cruise missile collaborative engagement

    Institute of Scientific and Technical Information of China (English)

    吴红; 杨峰; 王维平

    2012-01-01

    In order to response to complex and diverse battlefield environment, cruise missile needs to carry out task through dynamic collaboration. Nowadays, domestic and international researches which focus on cruise missile collaborative engagement have presented some dynamic cooperative modes, but all they have several drawbacks to some extent. Because of this, this paper puts forward a limited autonomy of central control of distributed collaboration, designs system business logic and analyzes system function in detail, then uses it as the background to carry out system architecture design of remote control collaboration based on symbiotic simulation.%为了应对体系对抗过程中复杂多变的战场环境,巡航导弹需通过动态协同执行作战任务.目前,国内外在巡航导弹协同作战的研究过程中,提出了几种动态协同模式,但都在一定程度上存在局限性.基于此,首先提出有限中央控制的分布式自主协同,对其系统业务逻辑进行了详细的设计和系统功能进行了详细的分析,并以此为背景开展基于共生仿真的远程控制协同系统体系结构设计.

  19. L'impact d'une simulation sur des dispositifs mobiles et en situation de collaboration sur la comprehension de l'effet photoelectrique au niveau collegial

    Science.gov (United States)

    Droui, Mohamed

    The educational innovation itself is sometimes debatable but it is justified when the teachers confront the learning difficulties of their students. In particular, some notions of physics are notoriously hard for students to understand, as is the case for the photoelectric effect which is not often comprehended by the students at the college level. This research tries to determine if, as part of a physics course, the simulation of the photoelectric effect and the use of mobile devices in collaborative situations facilitate an evolution of the student's conceptions about the concept of light. We have proceeded to develop a scenario of collaborative learning by integrating a simulation of the photoelectric effect on handheld devices (Pocket PC). The design of scenario was first influenced by our socioconstructivist vision of learning. We conducted two preliminary studies to complete our scenario of learning and to validate the platform " MobileSim " and the interface of the simulator used in our experiment. The first studies were completed with a simulation on computers and the second with a simulation on Pocket PC. After that, we carried out the experimentation with two groups of students. The control group was assigned to the traditional approach of teaching and the experimental group was assigned to the approach based on the developed scenario of collaborative learning. We have conducted a test twice to assess a conceptual change about the nature of light and about the phenomenon of the photoelectric effect and related concepts. The first test (pre-test) before the students are involved in the course and the second (post-test) after completion of experiments. Our results in the pre-test and post-test were completed by conducting semi-structured individual interviews with all students, by video recordings and recovered traces (on log files or on paper). Students in the experimental group obtained good results in the test compared to those of the control group. We

  20. 电压暂降对珠澳电网影响的仿真研究%Simulation Research on Influence on Zhuhai-Macao Power Grid by Voltage Sag

    Institute of Scientific and Technical Information of China (English)

    崔江静; 廖辰川; 彭显刚; 裴星宇; 吴熳红; 杨锐雄

    2016-01-01

    利用 PSD-BPA(power system department-Bonneville power administration,PSD-BPA)短路故障暂态仿真软件,以珠澳电网主网系统为研究对象,对珠澳电网不同站点发生三相短路故障引起的电压暂降进行仿真计算,并通过 ArcGIS (Arc Geographic Information System,ArcGIS)工具实现对电压暂降分布的可视化处理。仿真结果表明,珠海电网短路故障将对澳门电网产生较大的影响,其中输电通道发生短路故障对珠澳电网电压暂降的影响最严重且范围广,最后,结合珠澳电网整体情况对影响电压暂降因素进行分析并提出电网安全稳定运行的相关建议。%Taking the main network system of Zhuhai-Macao power grid as research object,power system department-Bon-neville power administration (PSD-BPA)short-circuit fault transient simulation software is used for simulating calculation on voltage sags caused by three-phase short-circuit faults of different sites of Zhuhai-Macao power grid,and ArcGIS tool is used to realize visualized process on distribution of voltage sags. Simulation results indicate that short-circuit faults of Zhuhai-Ma-cao power grid may cause great influence on Macao power grid and thereinto,short-circuit fault of power transmission chan-nel may have the most serious and a wide range of influence on voltage sags of Zhuhai-Macao power grid. Finally,this paper analyzes factors influencing voltage sags by combining the whole situation of Zhuhai-Macao power grid and proposes related suggestions about safe and stable operation of the power grid.

  1. Grid Databases for Shared Image Analysis in the MammoGrid Project

    CERN Document Server

    Amendolia, S R; Hauer, T; Manset, D; McClatchey, R; Odeh, M; Reading, T; Rogulin, D; Schottlander, D; Solomonides, T

    2004-01-01

    The MammoGrid project aims to prove that Grid infrastructures can be used for collaborative clinical analysis of database-resident but geographically distributed medical images. This requires: a) the provision of a clinician-facing front-end workstation and b) the ability to service real-world clinician queries across a distributed and federated database. The MammoGrid project will prove the viability of the Grid by harnessing its power to enable radiologists from geographically dispersed hospitals to share standardized mammograms, to compare diagnoses (with and without computer aided detection of tumours) and to perform sophisticated epidemiological studies across national boundaries. This paper outlines the approach taken in MammoGrid to seamlessly connect radiologist workstations across a Grid using an "information infrastructure" and a DICOM-compliant object model residing in multiple distributed data stores in Italy and the UK

  2. Pivotal Technology Research of Grid Based on Mobile Agent

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-wei; WANG Ru-chuan

    2004-01-01

    Grid Based on Mobile Agent is a new grid scheme. The purpose of the paper is to solve the pivotal technology of Grid Based on Mobile Agent ( GBMA) combined with thought of Virtual Organization ( VO). In GBMA, virtual organization is viewed as the basic management unit of the grid, and mobile agent is regarded as an important interactive means. Grid architecture, grid resource management and grid task management are the core technology problem of GBMA. The simulation results show that Inter- VO pattern has the obvious advantage because it can make full use of resources from other virtual organizations in GBMA environment.

  3. Power grid scheduling simulation and visual platform design oriented to security check%面向安全校核的电网调度仿真和可视化平台设计

    Institute of Scientific and Technical Information of China (English)

    洪道鉴; 王周虹; 洪蕾

    2016-01-01

    The traditional security check simulation visual platform of power grid scheduling can’t display the complex and various visual data normally,and has low simulation accuracy. Therefore,the dispatching simulation and visual platform were designed for security check. The platform is composed of the security check simulation module,simulation monitoring module and visual output module. The operation of the visual output module is done on the computer. The security check simulation mod⁃ule is responsible for the acquisition of simulation data in power grid,and generates the safety check instruction. The instruction is transmitted to the simulation monitoring module for safety check of electric facilities. The simulation monitoring module is used to monitor the power grid in real time. The visual output module receives the security check simulation data in security check simulation module and monitoring log in simulation monitoring module,and transforms them into 3D video and 2D image for the utilization of power grid dispatching manager. The update flow chart of the grid scheduling security check simulation and visual platform,and power grid security check language are set in software design. The experimental results show that the de⁃signed platform has high simulation accuracy and security check efficiency.%由于可视化数据复杂多样,传统的电网调度安全校核仿真可视化平台无法对其进行正常显示,仿真准确性较低。因此,设计面向安全校核的电网调度仿真和可视化平台,该平台由安全校核仿真模块、仿真监控模块和可视化输出模块组成。其中,可视化输出模块的操作全部在计算机上完成;安全校核仿真模块负责电网中安全仿真数据的获取,并将其生成安全校核指令,该指令会传输到仿真监控模块实现电网设施的安全校核,仿真监控模块对电网进行实时监控;可视化输出模块接收安全校核仿真模块中的

  4. GridPP returns to CERN

    CERN Multimedia

    Neasan O'Neill

    2011-01-01

    In early September, GridPP, the collaboration that manages the UK’s contribution to the worldwide LHC Computing Grid (wLCG), celebrated a decade of work by holding its twenty-seventh collaboration meeting at CERN.   Officially launched in September 2001, GridPP was one of the original partners in wLCG, funding much of the early work at CERN. Over the last decade GridPP has gone from a mere proposal to almost 30,000 CPUs working for researchers scattered across the globe. Twice a year, GridPP meets to discuss the progress and future plans of the community and this year, for the first time since 2004, decamped to CERN for this biannual meeting on the theme “GridPP in the International Context”. The main meeting was held over 2 days in the IT auditorium and was the perfect opportunity to have contributions from experts based at CERN, alongside those from within GridPP. Opening with a welcome from Frederic Hemmer, Head of the IT Department at CERN, the meeting began with...

  5. Simulation Analysis of Two-Stage Grid-connected PV Control System%两级式光伏并网发电控制系统仿真分析

    Institute of Scientific and Technical Information of China (English)

    肖恩恺; 毛玉蓉

    2013-01-01

    This paper introduces the structure and control of two-Stage grid-connected photovoltaic control system establishes photovoltaic array model and grid-connected photovoltaic model and simulates the output of grid-connected photovoltaic system with the change of il umination by photovoltaic array model.The results show that this two-level grid-connected photovoltaic system quickly and effectively tracks the maximum power point in photovoltaic array,accurately tracks the voltage phase as for grid-connected current control,assures the output current of inverter and the grid voltage of the same frequency and phase and guarantees the sinusoidal waveform with few ripples of current output.%  阐述了两级式光伏并网发电控制系统的结构及其控制过程,建立了光伏阵列模型和光伏并网发电系统模型,利用光伏阵列模型模拟了光照条件变化时光伏并网系统的输出情况进行仿真分析。实验表明,此两级式光伏并网发电系统能迅速有效地跟踪到光伏阵列的最大功率点,而且能够控制并网电流的波形,使逆变器的输出电流与电网电压同频同相,保证电流输出波形为正弦波。

  6. Kite Generator System: Grid Integration and Validation

    OpenAIRE

    Ahmed, Mariam; Hably, Ahmad; Bacha, Seddik; Ovalle, Andres

    2014-01-01

    International audience; In this paper, the problem of grid integration of a kite generator system (KGS), is handled. The mechanical power generated by the kite's traction is translated into an electrical one via a permanent magnet synchronous machine. This power is then injected in the grid or used to supply an isolated load after passing a power electronics interface. Control schemes have been developed for grid connected or stand-alone operation and tested on a hardware-in-the-loop simulator.

  7. The MammoGrid Project Grids Architecture

    CERN Document Server

    McClatchey, R; Manset, D; Hauer, T; Estrella, F; Saiz, P; Rogulin, D; Clatchey, Richard Mc; Buncic, Predrag; Manset, David; Hauer, Tamas; Estrella, Florida; Saiz, Pablo; Rogulin, Dmitri

    2003-01-01

    The aim of the recently EU-funded MammoGrid project is, in the light of emerging Grid technology, to develop a European-wide database of mammograms that will be used to develop a set of important healthcare applications and investigate the potential of this Grid to support effective co-working between healthcare professionals throughout the EU. The MammoGrid consortium intends to use a Grid model to enable distributed computing that spans national borders. This Grid infrastructure will be used for deploying novel algorithms as software directly developed or enhanced within the project. Using the MammoGrid clinicians will be able to harness the use of massive amounts of medical image data to perform epidemiological studies, advanced image processing, radiographic education and ultimately, tele-diagnosis over communities of medical "virtual organisations". This is achieved through the use of Grid-compliant services [1] for managing (versions of) massively distributed files of mammograms, for handling the distri...

  8. Nontrivial QoS. Switching the web to the grid

    Directory of Open Access Journals (Sweden)

    Mircea Mare

    2011-12-01

    Full Text Available The Internet provides no QoS, and from the looks of it, never will. We turn to the grid for a solution. In terms of QoS, existing grid technologies can bring a refreshing feel to the way we use the Web. The Internet evolved by interconnecting existing equipment (telephone lines while quality and security measures were later added to it's agenda, after the issues occurred. Grid architecture is being designed in a more proactive mindset. Grids have started being used not only for scientific purposes but also for communication, collaboration and transferring data. Switching to a grid-based Web and adding nontrivial QoS to the equation is a natural step forward. The paper compares the evolution of the Internet in parallel to the evolution of grids, providing Grid QoS solutions and arguing in favor of the switch to a grid-based Web.

  9. Grid-Free 2D Plasma Simulations of the Complex Interaction Between the Solar Wind and Small, Near-Earth Asteroids

    Science.gov (United States)

    Zimmerman, M. I.; Farrell, W. M.; Poppe, A. R.

    2014-01-01

    We present results from a new grid-free 2D plasma simulation code applied to a small, unmagnetized body immersed in the streaming solar wind plasma. The body was purposely modeled as an irregular shape in order to examine photoemission and solar wind plasma flow in high detail on the dayside, night-side, terminator and surface-depressed 'pocket' regions. Our objective is to examine the overall morphology of the various plasma interaction regions that form around a small body like a small near-Earth asteroid (NEA). We find that the object obstructs the solar wind flow and creates a trailing wake region downstream, which involves the interplay between surface charging and ambipolar plasma expansion. Photoemission is modeled as a steady outflow of electrons from illuminated portions of the surface, and under direct illumination the surface forms a non-monotonic or ''double-sheath'' electric potential upstream of the body, which is important for understanding trajectories and equilibria of lofted dust grains in the presence of a complex asteroid geometry. The largest electric fields are found at the terminators, where ambipolar plasma expansion in the body-sized night-side wake merges seamlessly with the thin photoelectric sheath on the dayside. The pocket regions are found to be especially complex, with nearby sunlit regions of positive potential electrically connected to unlit negative potentials and forming adjacent natural electric dipoles. For objects near the surface, we find electrical dissipation times (through collection of local environmental solar wind currents) that vary over at least 5 orders of magnitude: from 39 Micro(s) inside the near-surface photoelectron cloud under direct sunlight to less than 1 s inside the particle-depleted night-side wake and shadowed pocket regions

  10. The Computing and Data Grid Approach: Infrastructure for Distributed Science Applications

    Science.gov (United States)

    Johnston, William E.

    2002-01-01

    With the advent of Grids - infrastructure for using and managing widely distributed computing and data resources in the science environment - there is now an opportunity to provide a standard, large-scale, computing, data, instrument, and collaboration environment for science that spans many different projects and provides the required infrastructure and services in a relatively uniform and supportable way. Grid technology has evolved over the past several years to provide the services and infrastructure needed for building 'virtual' systems and organizations. We argue that Grid technology provides an excellent basis for the creation of the integrated environments that can combine the resources needed to support the large- scale science projects located at multiple laboratories and universities. We present some science case studies that indicate that a paradigm shift in the process of science will come about as a result of Grids providing transparent and secure access to advanced and integrated information and technologies infrastructure: powerful computing systems, large-scale data archives, scientific instruments, and collaboration tools. These changes will be in the form of services that can be integrated with the user's work environment, and that enable uniform and highly capable access to these computers, data, and instruments, regardless of the location or exact nature of these resources. These services will integrate transient-use resources like computing systems, scientific instruments, and data caches (e.g., as they are needed to perform a simulation or analyze data from a single experiment); persistent-use resources. such as databases, data catalogues, and archives, and; collaborators, whose involvement will continue for the lifetime of a project or longer. While we largely address large-scale science in this paper, Grids, particularly when combined with Web Services, will address a broad spectrum of science scenarios. both large and small scale.

  11. Introduction to grid computing

    CERN Document Server

    Magoules, Frederic; Tan, Kiat-An; Kumar, Abhinit

    2009-01-01

    A Thorough Overview of the Next Generation in ComputingPoised to follow in the footsteps of the Internet, grid computing is on the verge of becoming more robust and accessible to the public in the near future. Focusing on this novel, yet already powerful, technology, Introduction to Grid Computing explores state-of-the-art grid projects, core grid technologies, and applications of the grid.After comparing the grid with other distributed systems, the book covers two important aspects of a grid system: scheduling of jobs and resource discovery and monitoring in grid. It then discusses existing a

  12. MHD modeling on geodesic grids

    CERN Document Server

    Florinski, V; Balsara, D S; Meyer, C

    2013-01-01

    This report describes a new magnetohydrodynamic numerical model based on a hexagonal spherical geodesic grid. The model is designed to simulate astrophysical flows of partially ionized plasmas around a central compact object, such as a star or a planet with a magnetic field. The geodesic grid, produced by a recursive subdivision of a base platonic solid (an icosahedron), is free from control volume singularities inherent in spherical polar grids. Multiple populations of plasma and neutral particles, coupled via charge-exchange interactions, can be simulated simultaneously with this model. Our numerical scheme uses piecewise linear reconstruction on a surface of a sphere in a local two-dimensional "Cartesian" frame. The code employs HLL-type approximate Riemann solvers and includes facilities to control the divergence of magnetic field and maintain pressure positivity. Several test solutions are discussed, including a problem of an interaction between the solar wind and the local interstellar medium, and a sim...

  13. Grid refinement for entropic lattice Boltzmann models

    CERN Document Server

    Dorschner, B; Chikatamarla, S S; Karlin, I V

    2016-01-01

    We propose a novel multi-domain grid refinement technique with extensions to entropic incompressible, thermal and compressible lattice Boltzmann models. Its validity and accuracy are accessed by comparison to available direct numerical simulation and experiment for the simulation of isothermal, thermal and viscous supersonic flow. In particular, we investigate the advantages of grid refinement for the set-ups of turbulent channel flow, flow past a sphere, Rayleigh-Benard convection as well as the supersonic flow around an airfoil. Special attention is payed to analyzing the adaptive features of entropic lattice Boltzmann models for multi-grid simulations.

  14. A roadmap for caGrid, an enterprise Grid architecture for biomedical research.

    Science.gov (United States)

    Saltz, Joel; Hastings, Shannon; Langella, Stephen; Oster, Scott; Kurc, Tahsin; Payne, Philip; Ferreira, Renato; Plale, Beth; Goble, Carole; Ervin, David; Sharma, Ashish; Pan, Tony; Permar, Justin; Brezany, Peter; Siebenlist, Frank; Madduri, Ravi; Foster, Ian; Shanbhag, Krishnakant; Mead, Charlie; Chue Hong, Neil

    2008-01-01

    caGrid is a middleware system which combines the Grid computing, the service oriented architecture, and the model driven architecture paradigms to support development of interoperable data and analytical resources and federation of such resources in a Grid environment. The functionality provided by caGrid is an essential and integral component of the cancer Biomedical Informatics Grid (caBIG) program. This program is established by the National Cancer Institute as a nationwide effort to develop enabling informatics technologies for collaborative, multi-institutional biomedical research with the overarching goal of accelerating translational cancer research. Although the main application domain for caGrid is cancer research, the infrastructure provides a generic framework that can be employed in other biomedical research and healthcare domains. The development of caGrid is an ongoing effort, adding new functionality and improvements based on feedback and use cases from the community. This paper provides an overview of potential future architecture and tooling directions and areas of improvement for caGrid and caGrid-like systems. This summary is based on discussions at a roadmap workshop held in February with participants from biomedical research, Grid computing, and high performance computing communities.

  15. Stochastic optimization in the power grid

    NARCIS (Netherlands)

    Leenman, T.S.

    2012-01-01

    In this thesis steps are described to determine the locations of new wind mills which minimize energy loss on the Dutch High Voltage power grid. A vindication of the used power grid model is provided; the simulation procedure for stochastic wind power is described; and the required mathematical opti

  16. Switching Logic for Converting Off-grid PV Customers to On-grid by Utilizing Off-grid Inverter and Battery

    Science.gov (United States)

    Anishkumar, A. R.; Sreejaya, P.

    2016-12-01

    Kerala is a state in India having a very good potential for solar PV energy production. The domestic customers in Kerala using PV system are approximately 15 % and almost all of them are using the off-grid PV system. When these off grid customers move to on-grid system, off grid system accessories such as inverter and batteries become redundant. In this paper, a switching logic has been developed for the effective utilization of off grid accessories and reducing islanding power loss for on grid customers. An algorithm is proposed for the switching logic and it is verified using simulation results and hardware implementation.

  17. Incremental Trust in Grid Computing

    DEFF Research Database (Denmark)

    Brinkløv, Michael Hvalsøe; Sharp, Robin

    2007-01-01

    This paper describes a comparative simulation study of some incremental trust and reputation algorithms for handling behavioural trust in large distributed systems. Two types of reputation algorithm (based on discrete and Bayesian evaluation of ratings) and two ways of combining direct trust and ...... of Grid computing systems....

  18. Grid Access Methods and Applications

    NARCIS (Netherlands)

    Wiekens, B.

    2005-01-01

    In experimental sciences the need for IT facilities that can solve ever larger and more complex problems grows. Among these problems are large simulations and calculating physical models. Grid Computing offers techniques that allow computer resources to be shared among various organizations. Organiz

  19. Oracle joins CERN Openlab to advance grid computing

    CERN Multimedia

    2003-01-01

    "CERN and Oracle Corporation today announced that Oracle is joining the CERN openlab for DataGrid applications to collaborate in creating new grid computing technologies and exploring new computing and data management solutions far beyond today's Internet-based computing" (1 page).

  20. Grid Modernization Laboratory Consortium - Testing and Verification

    Energy Technology Data Exchange (ETDEWEB)

    Kroposki, Benjamin; Skare, Paul; Pratt, Rob; Kim, Tom; Ellis, Abraham

    2017-05-11

    This paper highlights some of the unique testing capabilities and projects being performed at several national laboratories as part of the U. S. Department of Energy Grid Modernization Laboratory Consortium. As part of this effort, the Grid Modernization Laboratory Consortium Testing Network isbeing developed to accelerate grid modernization by enablingaccess to a comprehensive testing infrastructure and creating a repository of validated models and simulation tools that will be publicly available. This work is key to accelerating thedevelopment, validation, standardization, adoption, and deployment of new grid technologies to help meet U. S. energy goals.