The core of smoothed particle hydrodynamics （SPH） is the nearest neighbor search subroutine. In this paper, a nearest neighbor search algorithm which is based on multiple background grids and support variable smooth...The core of smoothed particle hydrodynamics （SPH） is the nearest neighbor search subroutine. In this paper, a nearest neighbor search algorithm which is based on multiple background grids and support variable smooth length is introduced. Through tested on lid driven cavity flow, it is clear that this method can provide high accuracy. Analysis and experiments have been made on its parallelism, and the results show that this method has better parallelism and with adding processors its accuracy become higher, thus it achieves that efficiency grows in pace with accuracy.展开更多
This paper presents an automatic mesh generation procedure on a 2D domain based on a regular background grid. The idea is to devise a robust mesh generation scheme with equal emphasis on quality and efficiency. Instea...This paper presents an automatic mesh generation procedure on a 2D domain based on a regular background grid. The idea is to devise a robust mesh generation scheme with equal emphasis on quality and efficiency. Instead of using a traditional regular rectangular grid, a mesh of equilateral triangles is employed to ensure triangular element of the best quality will be preserved in the interior of the domain. As for the boundary, it is to be generated by a node/segment insertion process. Nodes are inserted into the background mesh one by one following the sequence of the domain boundary. The local structure of the mesh is modified based on the Delaunay criterion with the introduction of each node. Those boundary segments, which are not produced in the phase of node insertion, will be recovered through a systematic element swap process. Two theorems will be presented and proved to set up the theoretical basic of the boundary recovery part. Examples will be presented to demonstrate the robustness and the quality of the mesh generated by the proposed technique.展开更多
有源阻尼可显著提高变流器对弱电网的适应能力,然而,利用公共连接点(point of common coupling,PCC)点谐波电压进行有源阻尼控制时对系统背景谐波电压抑制能力的影响较大。为此,提出了一种基于PCC点谐波电压和并网电流的加权有源阻尼策...有源阻尼可显著提高变流器对弱电网的适应能力,然而,利用公共连接点(point of common coupling,PCC)点谐波电压进行有源阻尼控制时对系统背景谐波电压抑制能力的影响较大。为此,提出了一种基于PCC点谐波电压和并网电流的加权有源阻尼策略。文中基于系统误差传递关系分析了加权阻尼策略在提高变流器弱电网适应能力方面的有效性,并利用电网电压至系统误差的传递函数比较了加权和传统阻尼控制下系统的背景谐波电压抑制能力,结果表明,加权阻尼策略在提高变流器弱电网适应能力的同时可减小阻尼控制对系统背景谐波电压抑制能力的影响,提高并网电流质量。最后利用PLECS仿真验证了所得结果的正确性。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11002086)the Shanghai Leading Academic Discipline Project(Grant No.J50103)
文摘The core of smoothed particle hydrodynamics （SPH） is the nearest neighbor search subroutine. In this paper, a nearest neighbor search algorithm which is based on multiple background grids and support variable smooth length is introduced. Through tested on lid driven cavity flow, it is clear that this method can provide high accuracy. Analysis and experiments have been made on its parallelism, and the results show that this method has better parallelism and with adding processors its accuracy become higher, thus it achieves that efficiency grows in pace with accuracy.
文摘This paper presents an automatic mesh generation procedure on a 2D domain based on a regular background grid. The idea is to devise a robust mesh generation scheme with equal emphasis on quality and efficiency. Instead of using a traditional regular rectangular grid, a mesh of equilateral triangles is employed to ensure triangular element of the best quality will be preserved in the interior of the domain. As for the boundary, it is to be generated by a node/segment insertion process. Nodes are inserted into the background mesh one by one following the sequence of the domain boundary. The local structure of the mesh is modified based on the Delaunay criterion with the introduction of each node. Those boundary segments, which are not produced in the phase of node insertion, will be recovered through a systematic element swap process. Two theorems will be presented and proved to set up the theoretical basic of the boundary recovery part. Examples will be presented to demonstrate the robustness and the quality of the mesh generated by the proposed technique.
文摘有源阻尼可显著提高变流器对弱电网的适应能力,然而,利用公共连接点(point of common coupling,PCC)点谐波电压进行有源阻尼控制时对系统背景谐波电压抑制能力的影响较大。为此,提出了一种基于PCC点谐波电压和并网电流的加权有源阻尼策略。文中基于系统误差传递关系分析了加权阻尼策略在提高变流器弱电网适应能力方面的有效性,并利用电网电压至系统误差的传递函数比较了加权和传统阻尼控制下系统的背景谐波电压抑制能力,结果表明,加权阻尼策略在提高变流器弱电网适应能力的同时可减小阻尼控制对系统背景谐波电压抑制能力的影响,提高并网电流质量。最后利用PLECS仿真验证了所得结果的正确性。
