A partition of unity finite element method for numerical simulation of short wave propagation in solids is presented. The finite element spaces were constructed by multiplying the standard isoparametric finite element...A partition of unity finite element method for numerical simulation of short wave propagation in solids is presented. The finite element spaces were constructed by multiplying the standard isoparametric finite element shape functions, which form a partition of unity, with the local subspaces defined on the corresponding shape functions, which include a priori knowledge about the wave motion equation in trial spaces and approximately reproduce the highly oscillatory properties within a single element. Numerical examples demonstrate the performance of the proposed partition of unity finite element in both computational accuracy and efficiency.展开更多
The purpose of this study was to develop a quantitative structure–property relationship(QSPR) model based on the enhanced replacement method(ERM) and support vector machine(SVM) to predict the blood-to-brain barrier ...The purpose of this study was to develop a quantitative structure–property relationship(QSPR) model based on the enhanced replacement method(ERM) and support vector machine(SVM) to predict the blood-to-brain barrier partitioning behavior(log BB) of various drugs and organic compounds. Different molecular descriptors were calculated using a dragon package to represent the molecular structures of the compounds studied. The enhanced replacement method(ERM) was used to select the variables and construct the SVM model. The correlation coefficient, R^2, between experimental results and predicted log BB was 0.878 and 0.986, respectively. The results obtained demonstrated that, for all compounds, the log BB values estimated by SVM agreed with the experimental data, demonstrating that SVM is an effective method for model development, and can be used as a powerful chemometric tool in QSPR studies.展开更多
The space partitioning algorithm based on the rounding and addressing operations has been proved to be an efficient space partitioning algorithm with the potential for real-time calculation.An improvement on this kind...The space partitioning algorithm based on the rounding and addressing operations has been proved to be an efficient space partitioning algorithm with the potential for real-time calculation.An improvement on this kind of space partitioning algorithms for solving complex 3D models is presented.Numerical examples show that the efficiency of the improved algorithm is better than that of the original method.When the size of most target elements is smaller than the size of spatial grids,the efficiency of the improved method can be more than four times of that of the original method.An adaptive method of space partitioning based on the improved algorithm is developed by taking the surface element density or the curvature as the threshold for deep partitioning and conducting the deep partitioning using the octree method.A computer program implementation for applying the method in some typical applications is discussed,and the performance in terms of the efficiency,reliability,and resource use is evaluated.Application testing shows that the results of the adaptive spacing partitioning are more convenient for the follow-up use than that of the basic uniform space partitioning.Furthermore,when it is used to calculate the electromagnetic scattering of complex targets by the ray tracing(RT)method,the adaptive space partitioning algorithm can reduce the calculation time of the RT process by more than 40%compared with the uniform space segmentation algorithm.展开更多
随着高比例、大规模分布式光伏并网以及电动汽车的普及,如何发挥电动汽车灵活性、实现配电网分布式光伏与本地电动汽车负荷灵活性资源的友好协调是当前需要解决的重要问题。为此,提出了考虑电动汽车与分布式光伏协同的配电网集群划分与...随着高比例、大规模分布式光伏并网以及电动汽车的普及,如何发挥电动汽车灵活性、实现配电网分布式光伏与本地电动汽车负荷灵活性资源的友好协调是当前需要解决的重要问题。为此,提出了考虑电动汽车与分布式光伏协同的配电网集群划分与运行策略。首先,建立电动汽车可调充电功率灵活性聚合模型,提出基于Louvain算法的改进模块度指标配电网分布式集群划分方法;其次,基于历史数据信息生成电动汽车多时间尺度充电场景,提出考虑电动汽车充电灵活性的分布式集群协同优化模型;最后,采用同步交替方向乘子法(synchronous alternating direction multiplier method,SADMM)实现各集群优化模型的分布式求解。仿真结果表明,利用电动汽车充电灵活性参与配电网协同运行可有效提高分布式光伏利用率,并且在满足电动汽车用户充电需求的同时保证了配电网电压运行安全。展开更多
随着电动汽车的高速发展,越来越多的电动汽车接入配电网并与配电网进行互动。针对大规模电动汽车接入配电网带来的线路重过载现象,且考虑调度大规模电动汽车对配电网调控中心产生的通信压力,提出一种基于主从博弈的电动汽车参与城市电...随着电动汽车的高速发展,越来越多的电动汽车接入配电网并与配电网进行互动。针对大规模电动汽车接入配电网带来的线路重过载现象,且考虑调度大规模电动汽车对配电网调控中心产生的通信压力,提出一种基于主从博弈的电动汽车参与城市电网分层分区调控策略。首先提出了一种基于改进分区组合性的城市配电网分区方法,将负荷相似系数以及源荷匹配系数引入到分区参数中。基于分区结果,提出了分区控制下电动汽车双层博弈调度模型,上层模型为配电网调控中心在满足精细化削峰需求约束下的自身收益最大化,并制定了与下层电动汽车聚合商的交易电价;下层模型以聚合商内电动汽车用户用电成本最低为目标,合理安排电动汽车充放电计划,两者之间形成互动博弈并达到均衡解。最后,利用同步型交替方向乘子法(synchronous alternating direction methodofmultipliers,S-ADMM)算法实现了多区域的分布式并行求解,并基于南方某市266节点配电网进行仿真计算,验证了所提模型和方法的有效性。展开更多
分布式资源大规模并网要求配电网的灵活调控能力不断增强,如何充分利用多层级灵活性资源协助系统运行成为目前亟待解决的问题。为此,文中提供一种支撑多种资源接入配电网的分级自治协同策略。首先,分析多层级下灵活性资源特性,对分布式...分布式资源大规模并网要求配电网的灵活调控能力不断增强,如何充分利用多层级灵活性资源协助系统运行成为目前亟待解决的问题。为此,文中提供一种支撑多种资源接入配电网的分级自治协同策略。首先,分析多层级下灵活性资源特性,对分布式资源出力采用概率模型以减少其不确定性因素影响。其次,构建主变-馈线-台区分层分区优化调度模型,台区层进行内部自治并将等值结果传递给馈线层,馈线层基于网络架构和资源运行特性进行区域划分,实现兼顾系统安全性和经济性的主配协同优化,并采用基于谱惩罚参数的自适应交替方向乘子法(spectral penalty parameter based adaptive alternating direction method of multipliers,SPPA-ADMM)进行求解。最后,选用改进的IEEE 33节点算例进行仿真,仿真结果表明文中所采用的并行控制方式能有效提高优化求解的效率,验证了所提策略对多种分布式资源分级接入配电网运行调控具有指导意义。展开更多
基金Project supported by the National Basic Research Program of China (973Project) (No.2002CB412709) and the National Natural Science Foundation of China (Nos.50278012,10272027,19832010)
文摘A partition of unity finite element method for numerical simulation of short wave propagation in solids is presented. The finite element spaces were constructed by multiplying the standard isoparametric finite element shape functions, which form a partition of unity, with the local subspaces defined on the corresponding shape functions, which include a priori knowledge about the wave motion equation in trial spaces and approximately reproduce the highly oscillatory properties within a single element. Numerical examples demonstrate the performance of the proposed partition of unity finite element in both computational accuracy and efficiency.
文摘The purpose of this study was to develop a quantitative structure–property relationship(QSPR) model based on the enhanced replacement method(ERM) and support vector machine(SVM) to predict the blood-to-brain barrier partitioning behavior(log BB) of various drugs and organic compounds. Different molecular descriptors were calculated using a dragon package to represent the molecular structures of the compounds studied. The enhanced replacement method(ERM) was used to select the variables and construct the SVM model. The correlation coefficient, R^2, between experimental results and predicted log BB was 0.878 and 0.986, respectively. The results obtained demonstrated that, for all compounds, the log BB values estimated by SVM agreed with the experimental data, demonstrating that SVM is an effective method for model development, and can be used as a powerful chemometric tool in QSPR studies.
基金This work was supported by the National Natural Science Foundation of China(61601015,91538204).
文摘The space partitioning algorithm based on the rounding and addressing operations has been proved to be an efficient space partitioning algorithm with the potential for real-time calculation.An improvement on this kind of space partitioning algorithms for solving complex 3D models is presented.Numerical examples show that the efficiency of the improved algorithm is better than that of the original method.When the size of most target elements is smaller than the size of spatial grids,the efficiency of the improved method can be more than four times of that of the original method.An adaptive method of space partitioning based on the improved algorithm is developed by taking the surface element density or the curvature as the threshold for deep partitioning and conducting the deep partitioning using the octree method.A computer program implementation for applying the method in some typical applications is discussed,and the performance in terms of the efficiency,reliability,and resource use is evaluated.Application testing shows that the results of the adaptive spacing partitioning are more convenient for the follow-up use than that of the basic uniform space partitioning.Furthermore,when it is used to calculate the electromagnetic scattering of complex targets by the ray tracing(RT)method,the adaptive space partitioning algorithm can reduce the calculation time of the RT process by more than 40%compared with the uniform space segmentation algorithm.
文摘随着高比例、大规模分布式光伏并网以及电动汽车的普及,如何发挥电动汽车灵活性、实现配电网分布式光伏与本地电动汽车负荷灵活性资源的友好协调是当前需要解决的重要问题。为此,提出了考虑电动汽车与分布式光伏协同的配电网集群划分与运行策略。首先,建立电动汽车可调充电功率灵活性聚合模型,提出基于Louvain算法的改进模块度指标配电网分布式集群划分方法;其次,基于历史数据信息生成电动汽车多时间尺度充电场景,提出考虑电动汽车充电灵活性的分布式集群协同优化模型;最后,采用同步交替方向乘子法(synchronous alternating direction multiplier method,SADMM)实现各集群优化模型的分布式求解。仿真结果表明,利用电动汽车充电灵活性参与配电网协同运行可有效提高分布式光伏利用率,并且在满足电动汽车用户充电需求的同时保证了配电网电压运行安全。
文摘随着电动汽车的高速发展,越来越多的电动汽车接入配电网并与配电网进行互动。针对大规模电动汽车接入配电网带来的线路重过载现象,且考虑调度大规模电动汽车对配电网调控中心产生的通信压力,提出一种基于主从博弈的电动汽车参与城市电网分层分区调控策略。首先提出了一种基于改进分区组合性的城市配电网分区方法,将负荷相似系数以及源荷匹配系数引入到分区参数中。基于分区结果,提出了分区控制下电动汽车双层博弈调度模型,上层模型为配电网调控中心在满足精细化削峰需求约束下的自身收益最大化,并制定了与下层电动汽车聚合商的交易电价;下层模型以聚合商内电动汽车用户用电成本最低为目标,合理安排电动汽车充放电计划,两者之间形成互动博弈并达到均衡解。最后,利用同步型交替方向乘子法(synchronous alternating direction methodofmultipliers,S-ADMM)算法实现了多区域的分布式并行求解,并基于南方某市266节点配电网进行仿真计算,验证了所提模型和方法的有效性。
文摘分布式资源大规模并网要求配电网的灵活调控能力不断增强,如何充分利用多层级灵活性资源协助系统运行成为目前亟待解决的问题。为此,文中提供一种支撑多种资源接入配电网的分级自治协同策略。首先,分析多层级下灵活性资源特性,对分布式资源出力采用概率模型以减少其不确定性因素影响。其次,构建主变-馈线-台区分层分区优化调度模型,台区层进行内部自治并将等值结果传递给馈线层,馈线层基于网络架构和资源运行特性进行区域划分,实现兼顾系统安全性和经济性的主配协同优化,并采用基于谱惩罚参数的自适应交替方向乘子法(spectral penalty parameter based adaptive alternating direction method of multipliers,SPPA-ADMM)进行求解。最后,选用改进的IEEE 33节点算例进行仿真,仿真结果表明文中所采用的并行控制方式能有效提高优化求解的效率,验证了所提策略对多种分布式资源分级接入配电网运行调控具有指导意义。
