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
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
To address the issue of resource co-allocation with constraints to budget and deadline in grid environments, a novel co-allocation model based on virtual resource agent was proposed. The model optimized resources depl...To address the issue of resource co-allocation with constraints to budget and deadline in grid environments, a novel co-allocation model based on virtual resource agent was proposed. The model optimized resources deployment and price scheme through a three-side co-allocation mechanism, and applied queuing system to model the work of grid resources for providing quantitative deadline guarantees for grid applications. The validity and solutions of the model were presented theoretically. Extensive simulations were conducted to examine the effectiveness and the performance of the model by comparing with other co-allocation policies in terms of deadline violation rate, resource benefit and resource utilization. Experimental results show that compared with the three typical co-allocation policies, the proposed model can reduce the deadline violation rate to about 3.5% for the grid applications with constraints to budget and deadline. Also, the system benefits can be increased by about 30% compared with the those widely-used co-allocation policies.展开更多
Generally,tsunami waves become hazardous only when approaching the coast.Studying the runup and inundation of tsunami waves is important for understanding the tsunami evolution and for tsunami hazard assessment.Here,w...Generally,tsunami waves become hazardous only when approaching the coast.Studying the runup and inundation of tsunami waves is important for understanding the tsunami evolution and for tsunami hazard assessment.Here,we simulated the 1993 Hokkaido-Nansei-Oki(HNO) tsunami using a finite-difference model based on nonlinear shallow-water equations.We focused on the runup and inundation of tsunami wave propagation onto coastal area of Okushiri Island near Hokkaido,Japan,and investigate the relationship of different runup heights with the morphology and bathymetry of the seashore.In the simulation,a nested 4-layer grid system and moving boundary technique are adopted to study runup and inundation.The calculated tsunami heights and inundations in the region agreed well with field measurements.The local bathymetric and topographic characteristics had a first-order effect on the runup.Numerical experiments show that the focusing of certain local bathymetric features would amplify both wave height and current velocity remarkably.The results show that computation on dense grids is necessary to reproduce the observed runup heights,and inundation velocity is an important factor preventing tsunami devastation.In addition,we discussed the potential capability of sediment transport to illustrate the impact of tsunami waves on coastal geomorphology.展开更多
A novel method is presented to build the triangular surface model and calculate the tangential stress and strain of myocardial wall ,which can be further used to reflect the left ventricle twisting—a sensitive index ...A novel method is presented to build the triangular surface model and calculate the tangential stress and strain of myocardial wall ,which can be further used to reflect the left ventricle twisting—a sensitive index to assess the systolic and diastolic function of heart. Firstly, a point distribution model is used to obtain the feature points of the ventricular surface in medical images. Secondly, the surface model is constructed by triangular mesh, and then the subdivision strategy is introduced to refine the model. Thirdly, plane projection and finite element method(FEM) are applied to calculate the tangential stress and strain.Finally, the distribution of tangential modulus of elasticity is discussed. The stimulation results show that the proposed method can be used to compute the tangential stress and strain of myocardial wall effectively and the computing result is consistent with the results mentioned in the literatures.展开更多
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(60673165) supported by the National Natural Science Foundation of China
文摘To address the issue of resource co-allocation with constraints to budget and deadline in grid environments, a novel co-allocation model based on virtual resource agent was proposed. The model optimized resources deployment and price scheme through a three-side co-allocation mechanism, and applied queuing system to model the work of grid resources for providing quantitative deadline guarantees for grid applications. The validity and solutions of the model were presented theoretically. Extensive simulations were conducted to examine the effectiveness and the performance of the model by comparing with other co-allocation policies in terms of deadline violation rate, resource benefit and resource utilization. Experimental results show that compared with the three typical co-allocation policies, the proposed model can reduce the deadline violation rate to about 3.5% for the grid applications with constraints to budget and deadline. Also, the system benefits can be increased by about 30% compared with the those widely-used co-allocation policies.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-01)the National Natural Science Foundation of China (No.40576014)Science and Technology Planning Project of Guangdong Province,China (No.2005D33201006)
文摘Generally,tsunami waves become hazardous only when approaching the coast.Studying the runup and inundation of tsunami waves is important for understanding the tsunami evolution and for tsunami hazard assessment.Here,we simulated the 1993 Hokkaido-Nansei-Oki(HNO) tsunami using a finite-difference model based on nonlinear shallow-water equations.We focused on the runup and inundation of tsunami wave propagation onto coastal area of Okushiri Island near Hokkaido,Japan,and investigate the relationship of different runup heights with the morphology and bathymetry of the seashore.In the simulation,a nested 4-layer grid system and moving boundary technique are adopted to study runup and inundation.The calculated tsunami heights and inundations in the region agreed well with field measurements.The local bathymetric and topographic characteristics had a first-order effect on the runup.Numerical experiments show that the focusing of certain local bathymetric features would amplify both wave height and current velocity remarkably.The results show that computation on dense grids is necessary to reproduce the observed runup heights,and inundation velocity is an important factor preventing tsunami devastation.In addition,we discussed the potential capability of sediment transport to illustrate the impact of tsunami waves on coastal geomorphology.
基金supported by the National Natural Science Foundation of China and Microsoft Research Asia ( No. NSFC-60870002 No. 60802087)+2 种基金NCET and the Science and Technology Department of Zhejiang Province ( No. 2009C21008 No. 2010R10006 No. 2010C33095)
文摘A novel method is presented to build the triangular surface model and calculate the tangential stress and strain of myocardial wall ,which can be further used to reflect the left ventricle twisting—a sensitive index to assess the systolic and diastolic function of heart. Firstly, a point distribution model is used to obtain the feature points of the ventricular surface in medical images. Secondly, the surface model is constructed by triangular mesh, and then the subdivision strategy is introduced to refine the model. Thirdly, plane projection and finite element method(FEM) are applied to calculate the tangential stress and strain.Finally, the distribution of tangential modulus of elasticity is discussed. The stimulation results show that the proposed method can be used to compute the tangential stress and strain of myocardial wall effectively and the computing result is consistent with the results mentioned in the literatures.
