Networks are a class of general systems represented by becomes a weighted graph visualizing the constraints imposed their UC-structure. Suppressing the nature of elements the network by interconnections rather than th...Networks are a class of general systems represented by becomes a weighted graph visualizing the constraints imposed their UC-structure. Suppressing the nature of elements the network by interconnections rather than the elements themselves. These constraints follow generalized Kirchhoff＇s laws derived from physical constraints. Once we have a graph; then the working environment becomes the graph-theory. An algorithm derived from graph theory is developed within the paper in order to analyze general networks. The algorithm is based on computing all the spanning trees in the graph G with an associated weight. This weight is the product ofadmittance＇s of the edges forming the spanning tree. In the first phase this algorithm computes a depth first spanning tree together with its cotree. Both are used as parents for controlled generation of off-springs. The control is represented in selecting the off-springs that were not generated previously. While the generation of off-springs, is based on replacement of one or more tree edges by cycle edges corresponding to cotree edges. The algorithm can generate a frequency domain analysis of the network.展开更多
Tool path generated by space-filling curve always turns frequently causing trembling to machine,reducing toollife and affecting workpiece quality. Length and generation time of tool paths are both relatively long. In ...Tool path generated by space-filling curve always turns frequently causing trembling to machine,reducing toollife and affecting workpiece quality. Length and generation time of tool paths are both relatively long. In order to solve these problems,a toolpath generation method of NC milling based on space-filling curve is proposed. First,T-spline surface is regarded as the modeling surface,the grid,which is based on the limited scallop-height,can be got in the parameter space,and the influence value of grid node is determined. Second,a box is defined and planned,and the tool paths are got preliminarily,which is based on minimal spanning tree; Finally,based on an improved chamfering algorithm,the whole tool paths are got. A simulation system is developed for computer simulation,and an experiment is carried out to verify the method. The results of simulation and experiment show that the method is effective and feasible,and length and time of the tool paths are reduced.展开更多
Power systems can suffer outages,causing complete or partial disconnection of their power supply to load centers within the distribution networks.Distributed Generation(DG)plays an essential role in power systems.DG c...Power systems can suffer outages,causing complete or partial disconnection of their power supply to load centers within the distribution networks.Distributed Generation(DG)plays an essential role in power systems.DG can be used as a back-up power source to enhance the resiliency and reliability of a power system.Island mode operations after outages in an active distributing network(ADN)is an effective way to maintain continuity of the power supply to significant loads.It is a quite complicated task for power system operators to find the power flow path.Previous studies have primarily used pre-defined guidelines to find feasible power flow paths,and have focused on multiple islands for restoration.In these studies,possible restoration pathfinding with DG was the fundamental weakness,and furthermore,the power of DG was limited to pre-defined boundaries in the form of islands.Therefore,in this study,a new algorithm has been proposed,which uses the minimum spanning tree(MST)method to find the most feasible path.The proposed algorithm starts at any random node(in this case,DG),and progresses by selecting the next node with the least cost(weight),thus considering all the nodes through which power will flow.The proposed model is formulated as a multiobjective program considering the priority of loads and minimum power loss.The effectiveness of the proposed model is tested on a modified IEEE69-bus distribution system with the penetration of multiple distributed generation sources at different nodes.Results were compared with the strategies found in literature,and the proposed method was found to be feasible and efficient.展开更多
As China and Pakistan mark 55 years of diplomatic relations, the two countries are enhancing their strategic cooperation May 21 marks the 55th anniversary of the establishment of diplomatic ties between China and Paki...As China and Pakistan mark 55 years of diplomatic relations, the two countries are enhancing their strategic cooperation May 21 marks the 55th anniversary of the establishment of diplomatic ties between China and Pakistan. After more than a half century, the time-tested relationship between the two countries has developed into an "all-weather friendship" and "all-around cooperation" featuring a展开更多
文摘Networks are a class of general systems represented by becomes a weighted graph visualizing the constraints imposed their UC-structure. Suppressing the nature of elements the network by interconnections rather than the elements themselves. These constraints follow generalized Kirchhoff＇s laws derived from physical constraints. Once we have a graph; then the working environment becomes the graph-theory. An algorithm derived from graph theory is developed within the paper in order to analyze general networks. The algorithm is based on computing all the spanning trees in the graph G with an associated weight. This weight is the product ofadmittance＇s of the edges forming the spanning tree. In the first phase this algorithm computes a depth first spanning tree together with its cotree. Both are used as parents for controlled generation of off-springs. The control is represented in selecting the off-springs that were not generated previously. While the generation of off-springs, is based on replacement of one or more tree edges by cycle edges corresponding to cotree edges. The algorithm can generate a frequency domain analysis of the network.
基金Supported by the National Natural Science Foundation of China(No.51575143)
文摘Tool path generated by space-filling curve always turns frequently causing trembling to machine,reducing toollife and affecting workpiece quality. Length and generation time of tool paths are both relatively long. In order to solve these problems,a toolpath generation method of NC milling based on space-filling curve is proposed. First,T-spline surface is regarded as the modeling surface,the grid,which is based on the limited scallop-height,can be got in the parameter space,and the influence value of grid node is determined. Second,a box is defined and planned,and the tool paths are got preliminarily,which is based on minimal spanning tree; Finally,based on an improved chamfering algorithm,the whole tool paths are got. A simulation system is developed for computer simulation,and an experiment is carried out to verify the method. The results of simulation and experiment show that the method is effective and feasible,and length and time of the tool paths are reduced.
基金This work was supported in part by the National Natural Science Foundation of China(No.51677003)。
文摘Power systems can suffer outages,causing complete or partial disconnection of their power supply to load centers within the distribution networks.Distributed Generation(DG)plays an essential role in power systems.DG can be used as a back-up power source to enhance the resiliency and reliability of a power system.Island mode operations after outages in an active distributing network(ADN)is an effective way to maintain continuity of the power supply to significant loads.It is a quite complicated task for power system operators to find the power flow path.Previous studies have primarily used pre-defined guidelines to find feasible power flow paths,and have focused on multiple islands for restoration.In these studies,possible restoration pathfinding with DG was the fundamental weakness,and furthermore,the power of DG was limited to pre-defined boundaries in the form of islands.Therefore,in this study,a new algorithm has been proposed,which uses the minimum spanning tree(MST)method to find the most feasible path.The proposed algorithm starts at any random node(in this case,DG),and progresses by selecting the next node with the least cost(weight),thus considering all the nodes through which power will flow.The proposed model is formulated as a multiobjective program considering the priority of loads and minimum power loss.The effectiveness of the proposed model is tested on a modified IEEE69-bus distribution system with the penetration of multiple distributed generation sources at different nodes.Results were compared with the strategies found in literature,and the proposed method was found to be feasible and efficient.
文摘As China and Pakistan mark 55 years of diplomatic relations, the two countries are enhancing their strategic cooperation May 21 marks the 55th anniversary of the establishment of diplomatic ties between China and Pakistan. After more than a half century, the time-tested relationship between the two countries has developed into an "all-weather friendship" and "all-around cooperation" featuring a
