Economic dispatch(ED)aims to minimize the generation cost subject to power balance constraints.It is extensively used in power system operation and planning.ED problem as well as other problems with the same formulati...Economic dispatch(ED)aims to minimize the generation cost subject to power balance constraints.It is extensively used in power system operation and planning.ED problem as well as other problems with the same formulation are named as ED-type problems in this letter and a fast solution method is provided.The proposed method is achieved by solving a series of relaxed problems.With a closed-form solution for the relaxed ED-type problems,it is demonstrated that the proposed method consumes far less computing time and memory space than the off-the-shelf solvers and other quadratic programming(QP)methods.Finally,the effectiveness and computational efficiency of the proposed method are verified by the case studies,which shows the great potential in power system planning and operation.展开更多
This paper deals with the structural analysis problem of dynamic lumped process high-index differential algebraic equations(DAE)models.The existing graph theoretical method depends on the change in the relative positi...This paper deals with the structural analysis problem of dynamic lumped process high-index differential algebraic equations(DAE)models.The existing graph theoretical method depends on the change in the relative position of underspecified and overspecified subgraphs and has an effect to the value of the differential index for complex models.In this paper,we consider two methods for index reduction of such models by differentiation:Pryce’s method and the symbolic differential elimination algorithm rifsimp.They can remedy the above drawbacks.Discussion and comparison of these methods are given via a class of fundamental process simulation examples.In particular,the efficiency of Pryce’s method is illustrated as a function of the number of tanks in process design.Moreover,a range of nontrivial problems are demonstrated by the symbolic differential elimination algorithm and fast prolongation.展开更多
Direct Simulation Monte Carlo(DSMC)solves the Boltzmann equation with large Knudsen number.The Boltzmann equation generally consists of three terms:the force term,the diffusion term and the collision term.While the fi...Direct Simulation Monte Carlo(DSMC)solves the Boltzmann equation with large Knudsen number.The Boltzmann equation generally consists of three terms:the force term,the diffusion term and the collision term.While the first two terms of the Boltzmann equation can be discretized by numerical methods such as the finite volume method,the third term can be approximated by DSMC,and DSMC simulates the physical behaviors of gas molecules.However,because of the low sampling efficiency of Monte Carlo Simulation in DSMC,this part usually occupies large portion of computational costs to solve the Boltzmann equation.In this paper,by Markov Chain Monte Carlo(MCMC)and multicore programming,we develop Direct Simulation Multi-Chain Markov Chain Monte Carlo(DSMC3):a fast solver to calculate the numerical solution for the Boltzmann equation.Computational results show that DSMC3 is significantly faster than the conventional method DSMC.展开更多
针对传统车辆检索方法中存在准确性和区分度较低的问题,提出了一个基于改进SURF(speeded up robust features)算法的视频车辆检索方法。在车辆视频关键帧提取的基础上,根据改进SURF算法完成车辆图像的特征提取及匹配,其中包含改进FAST(f...针对传统车辆检索方法中存在准确性和区分度较低的问题,提出了一个基于改进SURF(speeded up robust features)算法的视频车辆检索方法。在车辆视频关键帧提取的基础上,根据改进SURF算法完成车辆图像的特征提取及匹配,其中包含改进FAST(features from accelerated segment test)特征点检测、SURF特征向量提取以及最近邻查询方法来进行特征点的匹配;通过计算比较待检索车辆图像与数据库车辆图像的相似度,算法完成图像筛选并反馈检索结果。实验结果表明:针对交通监控视频中待检索车辆,该方法能够较为准确地进行检索并反馈结果。展开更多
传统支持向量机分类过程的计算量和支持向量的个数成正比,当支持向量较多时,其分类过程的计算比较耗时。该文基于支持向量的稀疏性,证明了对支持向量压缩时,收紧新的快速决策函数和原始决策函数之间的误差等价于在样本空间对原始支持向...传统支持向量机分类过程的计算量和支持向量的个数成正比,当支持向量较多时,其分类过程的计算比较耗时。该文基于支持向量的稀疏性,证明了对支持向量压缩时,收紧新的快速决策函数和原始决策函数之间的误差等价于在样本空间对原始支持向量进行K均值聚类操作,据此提出了一种约简支持向量的快速分类算法FD-SVM(Fast Decision algorithm of Support Vector Machine),该算法首先对原始的支持向量进行特定比例的K均值聚类操作,聚类的中心为约简后新的支持向量,按照分类误差最小的原则构建优化模型,用二次规划方法求解得到新的支持向量的系数。标准数据集上的实验表明,保持分类精度的损失在统计意义上不明显的前提下,FD-SVM可以有效压缩支持向量的数量,提高分类速度。展开更多
基金This work was supported by the National Natural Science Foundation of China(No.51707146)the SGCC-National Natural Science Foundation of China Joint Program on Smart Grid(No.U1766205).
文摘Economic dispatch(ED)aims to minimize the generation cost subject to power balance constraints.It is extensively used in power system operation and planning.ED problem as well as other problems with the same formulation are named as ED-type problems in this letter and a fast solution method is provided.The proposed method is achieved by solving a series of relaxed problems.With a closed-form solution for the relaxed ED-type problems,it is demonstrated that the proposed method consumes far less computing time and memory space than the off-the-shelf solvers and other quadratic programming(QP)methods.Finally,the effectiveness and computational efficiency of the proposed method are verified by the case studies,which shows the great potential in power system planning and operation.
基金supported by the National Basic Research Program of China(2011CB302402)the National Natural Science Foundation of China(Grant Nos.91118001,11171053)+1 种基金the West Light Foundation of the Chinese Academy of Sciences,China Postdoctoral Science Foundation Funded Project(Grant No.2012M521692)the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists(Grant No.2010T2G31)。
文摘This paper deals with the structural analysis problem of dynamic lumped process high-index differential algebraic equations(DAE)models.The existing graph theoretical method depends on the change in the relative position of underspecified and overspecified subgraphs and has an effect to the value of the differential index for complex models.In this paper,we consider two methods for index reduction of such models by differentiation:Pryce’s method and the symbolic differential elimination algorithm rifsimp.They can remedy the above drawbacks.Discussion and comparison of these methods are given via a class of fundamental process simulation examples.In particular,the efficiency of Pryce’s method is illustrated as a function of the number of tanks in process design.Moreover,a range of nontrivial problems are demonstrated by the symbolic differential elimination algorithm and fast prolongation.
文摘Direct Simulation Monte Carlo(DSMC)solves the Boltzmann equation with large Knudsen number.The Boltzmann equation generally consists of three terms:the force term,the diffusion term and the collision term.While the first two terms of the Boltzmann equation can be discretized by numerical methods such as the finite volume method,the third term can be approximated by DSMC,and DSMC simulates the physical behaviors of gas molecules.However,because of the low sampling efficiency of Monte Carlo Simulation in DSMC,this part usually occupies large portion of computational costs to solve the Boltzmann equation.In this paper,by Markov Chain Monte Carlo(MCMC)and multicore programming,we develop Direct Simulation Multi-Chain Markov Chain Monte Carlo(DSMC3):a fast solver to calculate the numerical solution for the Boltzmann equation.Computational results show that DSMC3 is significantly faster than the conventional method DSMC.
文摘针对传统车辆检索方法中存在准确性和区分度较低的问题,提出了一个基于改进SURF(speeded up robust features)算法的视频车辆检索方法。在车辆视频关键帧提取的基础上,根据改进SURF算法完成车辆图像的特征提取及匹配,其中包含改进FAST(features from accelerated segment test)特征点检测、SURF特征向量提取以及最近邻查询方法来进行特征点的匹配;通过计算比较待检索车辆图像与数据库车辆图像的相似度,算法完成图像筛选并反馈检索结果。实验结果表明:针对交通监控视频中待检索车辆,该方法能够较为准确地进行检索并反馈结果。
文摘传统支持向量机分类过程的计算量和支持向量的个数成正比,当支持向量较多时,其分类过程的计算比较耗时。该文基于支持向量的稀疏性,证明了对支持向量压缩时,收紧新的快速决策函数和原始决策函数之间的误差等价于在样本空间对原始支持向量进行K均值聚类操作,据此提出了一种约简支持向量的快速分类算法FD-SVM(Fast Decision algorithm of Support Vector Machine),该算法首先对原始的支持向量进行特定比例的K均值聚类操作,聚类的中心为约简后新的支持向量,按照分类误差最小的原则构建优化模型,用二次规划方法求解得到新的支持向量的系数。标准数据集上的实验表明,保持分类精度的损失在统计意义上不明显的前提下,FD-SVM可以有效压缩支持向量的数量,提高分类速度。
