共享单车调配是优化城市交通资源配置的重要手段,但目前的最优路径调配方法往往对单车系统规模敏感。为此,研究一种分时段、区域间调配的共享单车投放方法,提出了带约束的游牧算法(nomad algorithm with constraints,NCA)求解调配模型...共享单车调配是优化城市交通资源配置的重要手段,但目前的最优路径调配方法往往对单车系统规模敏感。为此,研究一种分时段、区域间调配的共享单车投放方法,提出了带约束的游牧算法(nomad algorithm with constraints,NCA)求解调配模型的最优解。将单车调配问题建模为以单车流量为约束、以最小化运营损耗为目标的优化问题;提出求解上述模型的NCA算法,预测投放区域单车存量和区域间转移量,相比无约束的原游牧算法,改进了局部搜索和全局寻优策略,优化了部落初定位方法;基于预测的存量和转移量得出分时段区域间单车的调配方案。在上海和纽约相关数据集上的对比实验结果表明,运行时长约为其他方法的15%,租赁需求响应率高于分支定界算法0.15%,单车总数和运营损耗比遗传算法降低了约10%,验证了该方法具有更高的优化效率和用户需求响应率。展开更多
The application of multiple UAVs in complicated tasks has been widely explored in recent years.Due to the advantages of flexibility,cheapness and consistence,the performance of heterogeneous multi-UAVs with proper coo...The application of multiple UAVs in complicated tasks has been widely explored in recent years.Due to the advantages of flexibility,cheapness and consistence,the performance of heterogeneous multi-UAVs with proper cooperative task allocation is superior to over the single UAV.Accordingly,several constraints should be satisfied to realize the efficient cooperation,such as special time-window,variant equipment,specified execution sequence.Hence,a proper task allocation in UAVs is the crucial point for the final success.The task allocation problem of the heterogeneous UAVs can be formulated as a multi-objective optimization problem coupled with the UAV dynamics.To this end,a multi-layer encoding strategy and a constraint scheduling method are designed to handle the critical logical and physical constraints.In addition,four optimization objectives:completion time,target reward,UAV damage,and total range,are introduced to evaluate various allocation plans.Subsequently,to efficiently solve the multi-objective optimization problem,an improved multi-objective quantum-behaved particle swarm optimization(IMOQPSO)algorithm is proposed.During this algorithm,a modified solution evaluation method is designed to guide algorithmic evolution;both the convergence and distribution of particles are considered comprehensively;and boundary solutions which may produce some special allocation plans are preserved.Moreover,adaptive parameter control and mixed update mechanism are also introduced in this algorithm.Finally,both the proposed model and algorithm are verified by simulation experiments.展开更多
Based on the deficiency of time convergence and variability of Web services selection for services composition supporting cross-enterprises collaboration,an algorithm QCDSS(QoS constraints of dynamic Web services sele...Based on the deficiency of time convergence and variability of Web services selection for services composition supporting cross-enterprises collaboration,an algorithm QCDSS(QoS constraints of dynamic Web services selection)to resolve dynamic Web services selection with QoS global optimal path,was proposed.The essence of the algorithm was that the problem of dynamic Web services selection with QoS global optimal path was transformed into a multi-objective services composition optimization problem with QoS constraints.The operations of the cross and mutation in genetic algorithm were brought into PSOA(particle swarm optimization algorithm),forming an improved algorithm(IPSOA)to solve the QoS global optimal problem.Theoretical analysis and experimental results indicate that the algorithm can better satisfy the time convergence requirement for Web services composition supporting cross-enterprises collaboration than the traditional algorithms.展开更多
文摘共享单车调配是优化城市交通资源配置的重要手段,但目前的最优路径调配方法往往对单车系统规模敏感。为此,研究一种分时段、区域间调配的共享单车投放方法,提出了带约束的游牧算法(nomad algorithm with constraints,NCA)求解调配模型的最优解。将单车调配问题建模为以单车流量为约束、以最小化运营损耗为目标的优化问题;提出求解上述模型的NCA算法,预测投放区域单车存量和区域间转移量,相比无约束的原游牧算法,改进了局部搜索和全局寻优策略,优化了部落初定位方法;基于预测的存量和转移量得出分时段区域间单车的调配方案。在上海和纽约相关数据集上的对比实验结果表明,运行时长约为其他方法的15%,租赁需求响应率高于分支定界算法0.15%,单车总数和运营损耗比遗传算法降低了约10%,验证了该方法具有更高的优化效率和用户需求响应率。
基金Project(61801495)supported by the National Natural Science Foundation of China
文摘The application of multiple UAVs in complicated tasks has been widely explored in recent years.Due to the advantages of flexibility,cheapness and consistence,the performance of heterogeneous multi-UAVs with proper cooperative task allocation is superior to over the single UAV.Accordingly,several constraints should be satisfied to realize the efficient cooperation,such as special time-window,variant equipment,specified execution sequence.Hence,a proper task allocation in UAVs is the crucial point for the final success.The task allocation problem of the heterogeneous UAVs can be formulated as a multi-objective optimization problem coupled with the UAV dynamics.To this end,a multi-layer encoding strategy and a constraint scheduling method are designed to handle the critical logical and physical constraints.In addition,four optimization objectives:completion time,target reward,UAV damage,and total range,are introduced to evaluate various allocation plans.Subsequently,to efficiently solve the multi-objective optimization problem,an improved multi-objective quantum-behaved particle swarm optimization(IMOQPSO)algorithm is proposed.During this algorithm,a modified solution evaluation method is designed to guide algorithmic evolution;both the convergence and distribution of particles are considered comprehensively;and boundary solutions which may produce some special allocation plans are preserved.Moreover,adaptive parameter control and mixed update mechanism are also introduced in this algorithm.Finally,both the proposed model and algorithm are verified by simulation experiments.
基金Project(70631004)supported by the Key Project of the National Natural Science Foundation of ChinaProject(20080440988)supported by the Postdoctoral Science Foundation of China+1 种基金Project(09JJ4030)supported by the Natural Science Foundation of Hunan Province,ChinaProject supported by the Postdoctoral Science Foundation of Central South University,China
文摘Based on the deficiency of time convergence and variability of Web services selection for services composition supporting cross-enterprises collaboration,an algorithm QCDSS(QoS constraints of dynamic Web services selection)to resolve dynamic Web services selection with QoS global optimal path,was proposed.The essence of the algorithm was that the problem of dynamic Web services selection with QoS global optimal path was transformed into a multi-objective services composition optimization problem with QoS constraints.The operations of the cross and mutation in genetic algorithm were brought into PSOA(particle swarm optimization algorithm),forming an improved algorithm(IPSOA)to solve the QoS global optimal problem.Theoretical analysis and experimental results indicate that the algorithm can better satisfy the time convergence requirement for Web services composition supporting cross-enterprises collaboration than the traditional algorithms.
