Based on the advantages of both Grid and peer-to-peer （P2P） networks, an overlay network in the Grid environment is constructed by P2P technologies by a modified version of the Chord protocol. In this mechanism, dif...Based on the advantages of both Grid and peer-to-peer （P2P） networks, an overlay network in the Grid environment is constructed by P2P technologies by a modified version of the Chord protocol. In this mechanism, different nodes＇ accesses to different resources are determined by their contribution. Therefore, the heterogeneous resources of virtual organizations in large-scale Grid can be effectively integrated, and the key node failure as well as system bottleneck in the traditional Grid environment is eliminated. The experimental results indicate that this management mechanism can achieve better average performance in the Grid environment and maintain the P2P characteristics as well.展开更多
A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical n...A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical non-equilibrium reactions encounters the stiffness problem, thus taking huge CPU time. Based on the domain decomposition method, a high efficient automatic domain decomposer for three-dimensional hybrid meshes is developed, and then implemented to the numerical simulation of hypersonic flows. Control equations are multicomponent N-S equations, and spatially discretized scheme is used by a cell-centered finite volume algorithm with a five-stage Runge-Kutta time step. The chemical kinetic model is a seven species model with weak ionization. A point-implicit method is used to solve the chemical source term. Numerical results on PC-Cluster are verified on a bi-ellipse model compared with references.展开更多
An adaptive method for the solution of compressible flows is described. The idea results from the desire for an efficient grid system,and an accurate and robust solution method are used to resolve flow features of the...An adaptive method for the solution of compressible flows is described. The idea results from the desire for an efficient grid system,and an accurate and robust solution method are used to resolve flow features of the interest. The adaptation flow solution is proposed,including the detection of flow features based on the matrix error; the mesh adaptation using the mesh movement,the mesh refinement,the mesh coarsening,and their combination. The feature detection based on the matrix error can maintain the high resolution property for shock waves of the one-dimensional approximate Riemann solver and the higher order reconstruction scheme. The high grid efficiency is obtained with the anisotropically directional grid corresponding to feature directions,and the error of the flow-field is averaged. The procedure and its application to flow solutions of shock waves are described. Results validate that the method is reliable.展开更多
To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated ...To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.展开更多
In order to get some useful parameters for grid generation of catamaran, the CFD software FLUENT is used to investigate the main effects of grid generation on flow field calculation. The influences of some elements ar...In order to get some useful parameters for grid generation of catamaran, the CFD software FLUENT is used to investigate the main effects of grid generation on flow field calculation. The influences of some elements are investigated with a series of calculations in the present paper, and some alteratives are proposed. The proposed alteratives based on the analysis of the effects are used for a catamaran resistance calculation, comparisons of the calculated results with experimental data show good agreement. It shows that the research result of this paver is useful for the numerical calculation of catamaran.展开更多
In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning meth...In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods （vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms） in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.展开更多
The unintentional islanding of micro-grid may cause negative impacts on distribution loads and distributed generations,so it must be detected within the acceptable duration.In this paper a new islanding detection algo...The unintentional islanding of micro-grid may cause negative impacts on distribution loads and distributed generations,so it must be detected within the acceptable duration.In this paper a new islanding detection algorithm is proposed.This algorithm introduces the frequency feedback method by the reactive power compensation to derive the frequency continuous shift. Accordingly,the islanding can be detected by monitoring the frequency within 0.1 s.The simulation results prove that this algorithm has extremely small non-detection zone,and meanwhile it presents an excellent islanding detection speed as well.展开更多
Calculation grid and turbulence model for numerical simulating pressure fluctuations in a high-speed train tunnel are studied through the comparison analysis of numerical simulation and moving model test.Compared the ...Calculation grid and turbulence model for numerical simulating pressure fluctuations in a high-speed train tunnel are studied through the comparison analysis of numerical simulation and moving model test.Compared the waveforms and peak-peak values of pressure fluctuations between numerical simulation and moving model test,the structured grid and the SST k-ωturbulence model are selected for numerical simulating the process of high-speed train passing through the tunnel.The largest value of pressure wave amplitudes of numerical simulation and moving model test meet each other.And the locations of the largest value of the initial compression and expansion wave amplitude of numerical simulation are in agreement with that of moving model test.The calculated pressure at the measurement point fully conforms to the propagation law of compression and expansion waves in the tunnel.展开更多
This paper proposes a new algorithm for determining the starting points of contour lines. The new algorithm is based on the interval tree. The result improves the algorithm＇s efficiency remarkably. Further, a new str...This paper proposes a new algorithm for determining the starting points of contour lines. The new algorithm is based on the interval tree. The result improves the algorithm＇s efficiency remarkably. Further, a new strategy is designed to constrain the direction of threading and the resulting contour bears more meaningful information.展开更多
A multiphysics model for a production scale planar solid oxide fuel cell （SOFC） stack is important for the SOFC technology, but usually requires an unpractical amount of computing resource. The major cause for the h...A multiphysics model for a production scale planar solid oxide fuel cell （SOFC） stack is important for the SOFC technology, but usually requires an unpractical amount of computing resource. The major cause for the huge computing resource requirement is identified as the need to solve the cathode O2 transport and the associated electrochemistry. To overcome the technical obstacle, an analytical model for solving the O2 transport and its coupling with the electrochemistry is derived. The analytical model is used to greatly reduce the numerical mesh complexity of a multiphysics model. Numerical test shows that the analytical approximation is highly accurate and stable. A multiphysics numerical modeling tool taking advantage of the analytical solution is then developed through Fluent@. The numerical efficiency and stability of this modeling tool are further demonstrated by simulating a 30- cell stack with a production scale cell size. Detailed information about the stack performance is revealed and briefly discussed. The multiphysics modeling tool can be used to guide the stack design and select the operating parameters.展开更多
An effective assemble-oriented framework for grid Web service based on open grid service architecture was proposed,in which Web service semantics network constructed by software reuse was designed to enhance the locat...An effective assemble-oriented framework for grid Web service based on open grid service architecture was proposed,in which Web service semantics network constructed by software reuse was designed to enhance the locating of assemble-oriented service resources.The successful Web services assembled structure was exploited to design semantics network,the logical and the physical structure of the resource was separated in Web service,and the logical resource derived from type ID of Web service was combined with semantic structure.The organizing protocol,data structures and the mechanism of implementation in the model were presented.Experiment results show that the success ratio of Web service request comes to 100% while providing completely assembly semantics set.This model provides guarantee of the reliability of assemble Web service and establishes the foundation of Web service automatic interaction,customizing application service and dynamic service configuration.展开更多
基金The National Natural Science Foundation of China(No60573133)the National Basic Research Program of China (973Program)(No2003CB314801)
文摘Based on the advantages of both Grid and peer-to-peer （P2P） networks, an overlay network in the Grid environment is constructed by P2P technologies by a modified version of the Chord protocol. In this mechanism, different nodes＇ accesses to different resources are determined by their contribution. Therefore, the heterogeneous resources of virtual organizations in large-scale Grid can be effectively integrated, and the key node failure as well as system bottleneck in the traditional Grid environment is eliminated. The experimental results indicate that this management mechanism can achieve better average performance in the Grid environment and maintain the P2P characteristics as well.
文摘A parallel virtual machine （PVM） protocol based parallel computation of 3-D hypersonic flows with chemical non-equilibrium on hybrid meshes is presented. The numerical simulation for hypersonic flows with chemical non-equilibrium reactions encounters the stiffness problem, thus taking huge CPU time. Based on the domain decomposition method, a high efficient automatic domain decomposer for three-dimensional hybrid meshes is developed, and then implemented to the numerical simulation of hypersonic flows. Control equations are multicomponent N-S equations, and spatially discretized scheme is used by a cell-centered finite volume algorithm with a five-stage Runge-Kutta time step. The chemical kinetic model is a seven species model with weak ionization. A point-implicit method is used to solve the chemical source term. Numerical results on PC-Cluster are verified on a bi-ellipse model compared with references.
文摘An adaptive method for the solution of compressible flows is described. The idea results from the desire for an efficient grid system,and an accurate and robust solution method are used to resolve flow features of the interest. The adaptation flow solution is proposed,including the detection of flow features based on the matrix error; the mesh adaptation using the mesh movement,the mesh refinement,the mesh coarsening,and their combination. The feature detection based on the matrix error can maintain the high resolution property for shock waves of the one-dimensional approximate Riemann solver and the higher order reconstruction scheme. The high grid efficiency is obtained with the anisotropically directional grid corresponding to feature directions,and the error of the flow-field is averaged. The procedure and its application to flow solutions of shock waves are described. Results validate that the method is reliable.
基金The National Natural Science Foundation of China(No60673054,90412012)
文摘To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.
基金Supported by the Foundation of Multihull Ship Technology,Key Laboratory of Fundamental Science for National Defence under Grant No.002010260737
文摘In order to get some useful parameters for grid generation of catamaran, the CFD software FLUENT is used to investigate the main effects of grid generation on flow field calculation. The influences of some elements are investigated with a series of calculations in the present paper, and some alteratives are proposed. The proposed alteratives based on the analysis of the effects are used for a catamaran resistance calculation, comparisons of the calculated results with experimental data show good agreement. It shows that the research result of this paver is useful for the numerical calculation of catamaran.
基金This research work is supported by the Projects of National Science Foundation of China （Grant No, 40574052 and 40437018） and National Basic Research Program of China （973 Program） （Grant No. 2007CB209603）.Acknowledgements We wish to thank Researcher Xu Tao for his advice and comment. We also thank Mrs. Wang Kun for her help in the process of translation.
文摘In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods （vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms） in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.
基金National High-Tech R&D Program of China(No.2007AA05Z241).
文摘The unintentional islanding of micro-grid may cause negative impacts on distribution loads and distributed generations,so it must be detected within the acceptable duration.In this paper a new islanding detection algorithm is proposed.This algorithm introduces the frequency feedback method by the reactive power compensation to derive the frequency continuous shift. Accordingly,the islanding can be detected by monitoring the frequency within 0.1 s.The simulation results prove that this algorithm has extremely small non-detection zone,and meanwhile it presents an excellent islanding detection speed as well.
文摘Calculation grid and turbulence model for numerical simulating pressure fluctuations in a high-speed train tunnel are studied through the comparison analysis of numerical simulation and moving model test.Compared the waveforms and peak-peak values of pressure fluctuations between numerical simulation and moving model test,the structured grid and the SST k-ωturbulence model are selected for numerical simulating the process of high-speed train passing through the tunnel.The largest value of pressure wave amplitudes of numerical simulation and moving model test meet each other.And the locations of the largest value of the initial compression and expansion wave amplitude of numerical simulation are in agreement with that of moving model test.The calculated pressure at the measurement point fully conforms to the propagation law of compression and expansion waves in the tunnel.
基金Grant from LIESMARS (No.WKL(06)0302)the Basic Research Grant of CASM(No.G7721)
文摘This paper proposes a new algorithm for determining the starting points of contour lines. The new algorithm is based on the interval tree. The result improves the algorithm＇s efficiency remarkably. Further, a new strategy is designed to constrain the direction of threading and the resulting contour bears more meaningful information.
基金This work is supported the National Natural Science Foundation of China （No. 11374272 and No. 11574284）, the National Basic Research Program of China （No.2012CB215405） and Collaborative Innovation Center of Suzhou Nano Science and Technology are gratefully acknowledged.
文摘A multiphysics model for a production scale planar solid oxide fuel cell （SOFC） stack is important for the SOFC technology, but usually requires an unpractical amount of computing resource. The major cause for the huge computing resource requirement is identified as the need to solve the cathode O2 transport and the associated electrochemistry. To overcome the technical obstacle, an analytical model for solving the O2 transport and its coupling with the electrochemistry is derived. The analytical model is used to greatly reduce the numerical mesh complexity of a multiphysics model. Numerical test shows that the analytical approximation is highly accurate and stable. A multiphysics numerical modeling tool taking advantage of the analytical solution is then developed through Fluent@. The numerical efficiency and stability of this modeling tool are further demonstrated by simulating a 30- cell stack with a production scale cell size. Detailed information about the stack performance is revealed and briefly discussed. The multiphysics modeling tool can be used to guide the stack design and select the operating parameters.
基金Project (60573127) supported by the National Natural Science Foundation of ChinaProject (06023960) supported by the Natural Science Foundation of Guangdong Province, ChinaProject (06JJ30032) supported by the Natural Science Foundation of Hunan Province, China
文摘An effective assemble-oriented framework for grid Web service based on open grid service architecture was proposed,in which Web service semantics network constructed by software reuse was designed to enhance the locating of assemble-oriented service resources.The successful Web services assembled structure was exploited to design semantics network,the logical and the physical structure of the resource was separated in Web service,and the logical resource derived from type ID of Web service was combined with semantic structure.The organizing protocol,data structures and the mechanism of implementation in the model were presented.Experiment results show that the success ratio of Web service request comes to 100% while providing completely assembly semantics set.This model provides guarantee of the reliability of assemble Web service and establishes the foundation of Web service automatic interaction,customizing application service and dynamic service configuration.
