Two classes of mixed-integer nonlinear bilevel programming problems are discussed. One is that the follower＇s functions are separable with respect to the follower＇s variables, and the other is that the follower＇s f...Two classes of mixed-integer nonlinear bilevel programming problems are discussed. One is that the follower＇s functions are separable with respect to the follower＇s variables, and the other is that the follower＇s functions are convex if the follower＇s variables are not restricted to integers. A genetic algorithm based on an exponential distribution is proposed for the aforementioned problems. First, for each fixed leader＇s variable x, it is proved that the optimal solution y of the follower＇s mixed-integer programming can be obtained by solving associated relaxed problems, and according to the convexity of the functions involved, a simplified branch and bound approach is given to solve the follower＇s programming for the second class of problems. Furthermore, based on an exponential distribution with a parameter λ, a new crossover operator is designed in which the best individuals are used to generate better offspring of crossover. The simulation results illustrate that the proposed algorithm is efficient and robust.展开更多
目的针对冷链运输中的生鲜打包及装载优化问题,提出一种允许货物以体积恒定为前提进行尺寸变化的包装装载方案,以最大化集装箱的空间利用率。方法基于上述问题,构建非线性混合整数规划模型,为了方便CPLEX或LINGO等求解器对该非线性混合...目的针对冷链运输中的生鲜打包及装载优化问题,提出一种允许货物以体积恒定为前提进行尺寸变化的包装装载方案,以最大化集装箱的空间利用率。方法基于上述问题,构建非线性混合整数规划模型,为了方便CPLEX或LINGO等求解器对该非线性混合整数规划模型进行求解,采用一种分段线性化方法,将该非线性模型进行线性化处理。由于所研究问题具有NP-hard属性,无论是CPLEX还是LINGO都无法有效求解大规模算例,因此设计一种有效结合遗传算法与深度、底部、左部方向优先装载(Deepest bottom left with fill,DBLF)的算法。结果大小规模算例实验验证结果表明,混合遗传算法能够在合理时间内获得最优解或近似最优解。结论所提出的可变尺寸包装方案有效提高了装载率,有益于客户和物流公司。展开更多
馈线区段故障的快速准确辨识对于提升配电网可靠性与自愈性有重要作用。针对基于逻辑关系的间接故障定位方法在数值稳定性和决策效率上的不足,该文基于代数关系描述和互补约束理论构建了配电网故障区段定位的互补约束新模型,其优势在于...馈线区段故障的快速准确辨识对于提升配电网可靠性与自愈性有重要作用。针对基于逻辑关系的间接故障定位方法在数值稳定性和决策效率上的不足,该文基于代数关系描述和互补约束理论构建了配电网故障区段定位的互补约束新模型,其优势在于:1)避免了对群体智能算法的过分依赖,可采用数值稳定性好的梯度算法优化求解;2)利用互补约束条件将离散变量松弛为连续变量,降低了故障定位问题决策时的复杂性。在此基础上,提出基于扰动因子的故障定位模型光滑化求解算法。仿真表明,新模型和决策算法不仅能够实现馈线故障区段的准确高容错性辨识,且进行优化决策时具有数值稳定性好、优化效率高的优点,在大规模配电网故障定位中有良好的应用前景。Fast and exact feeder fault location method plays an important role in enhancing reliability and self-healing of distribution network.Logic relationship based conventional indirect fault location model and method has the drawbacks of excessive reliance on swarm intelligence algorithm in optimization computation,numerical optimization instability and low decision-making efficiency.In order to overcome the above shortcomings,on basis of algebra relationship description and complementary theory,a novel complementarity constraints fault location model is proposed as follows:1min()()1,0[(1),(2),,()],[(1),(2),,()],0,,i N S i N N f KB x x x NκκκN=?=???+=⊥=?==?≥∈∈?X∑X X X X X XκκκκRκR(1)Because the feasible points of the above complementarity constraints model can not satisfy the nonlinear programming constraint specification,the optimal solution can not be obtained by using the nonlinear programming to satisfy the Karush-Kuhn-Tucker(KKT)condition.In order to solve the novel fault location model effectively used by nonlinear programming directly,the Fischer-Burmeister auxiliary function with the perturbation factor is used to transform the complementarity constraints fault location model into a continuous smoothing model,which can satisfy the B-stability point.The smoothing model for fault location with complementarity constraints can be expressed as:212 2 2min(,,)()()()()11 2 0()()0[(1),(2),,()][(1),(2),,()][(1),(2),,()],0,N i N N F f i f x x x N N Nφφεφκκκεεε=?=+??=??+=??-++=??=?=?=??=?≥??∈∈?∑X X X XεX XκεX XκεεεκκεκRεR(2)In this model,the feasible point satisfies the nonlinear constraint specification,which can be solved by nonlinear programming directly.When the value of the perturbation factor tends to zero and the KKT extremum condition is established,the optimal decision vector of the fault location model can be obtained,so that the feeder fault section can be found.The correctness and effectiveness of the fault location model with complementarity constraints are verified by(sequence quadratic program)SQP in Matlab2010 a simulation platform.The simulation study shows that:1)The novel model of distribution network fault location based on the theory of complementarity constraints can effectively reflect the correlation characteristics between the causal devices,which can accurately locate the fault section of the feeder fault,and has high fault tolerance.2)The model is proposed based on relational algebra description modeling,so in optimization decision process can avoid the fault identification model excessive reliance on swarm intelligence algorithm in optimization computation,in which the gradient algorithm with good numerical stability can be used,which has the advantage in numerical stability.3)By through the feeder fault status information complementarity constraints conditions,the fault identification model can be transformed from discrete optimization space to continuous optimization space,which can effectively reduce the complexity of fault location model in optimization decision.4)The smoothing method based on the perturbation factor auxiliary penalty function can improve the non-smoothing characteristics of the complementarity constraints model,which can lead the optimal value to converge to the stable point,so as to accurately locate the feeder fault section.5)The novel fault location model and decision method proposed in this paper can be applied to the feeder fault location problem in large scale distribution network.展开更多
基金supported by the National Natural Science Fundation of China (60374063)
文摘Two classes of mixed-integer nonlinear bilevel programming problems are discussed. One is that the follower＇s functions are separable with respect to the follower＇s variables, and the other is that the follower＇s functions are convex if the follower＇s variables are not restricted to integers. A genetic algorithm based on an exponential distribution is proposed for the aforementioned problems. First, for each fixed leader＇s variable x, it is proved that the optimal solution y of the follower＇s mixed-integer programming can be obtained by solving associated relaxed problems, and according to the convexity of the functions involved, a simplified branch and bound approach is given to solve the follower＇s programming for the second class of problems. Furthermore, based on an exponential distribution with a parameter λ, a new crossover operator is designed in which the best individuals are used to generate better offspring of crossover. The simulation results illustrate that the proposed algorithm is efficient and robust.
文摘半挂车辆的非稳定运动学特性为其泊车过程中自主运动规划带来严峻挑战。针对半挂车在多障碍物的静态场景中泊车运动规划算法效率低、结果平滑性差等问题,本文提出了序列式运动规划方法(sequential motion planning algorithm,SMPA)。首先,提出了基于二次规划策略和改进双向快速扩展随机树(bidirectional rapidly-exploring random tree algorithm,Bi-RRT)的初始路径生成方法。然后,结合车辆非完整微分约束下的路径节点可行性判别方法研究,提出基于概率的目标偏向采样策略,提高了采样效率。最后,构建了面向车辆系统控制变量连续性的非线性最优化控制模型,解决泊车换向点的对接问题,提高了泊车轨迹平滑性。仿真结果表明,该方法在多障碍物场景中,规划时间相比Hybrid A*和Bi-RRT分别降低了86.71%和21.44%,轨迹质量也更具优越性。
文摘目的针对冷链运输中的生鲜打包及装载优化问题,提出一种允许货物以体积恒定为前提进行尺寸变化的包装装载方案,以最大化集装箱的空间利用率。方法基于上述问题,构建非线性混合整数规划模型,为了方便CPLEX或LINGO等求解器对该非线性混合整数规划模型进行求解,采用一种分段线性化方法,将该非线性模型进行线性化处理。由于所研究问题具有NP-hard属性,无论是CPLEX还是LINGO都无法有效求解大规模算例,因此设计一种有效结合遗传算法与深度、底部、左部方向优先装载(Deepest bottom left with fill,DBLF)的算法。结果大小规模算例实验验证结果表明,混合遗传算法能够在合理时间内获得最优解或近似最优解。结论所提出的可变尺寸包装方案有效提高了装载率,有益于客户和物流公司。
文摘馈线区段故障的快速准确辨识对于提升配电网可靠性与自愈性有重要作用。针对基于逻辑关系的间接故障定位方法在数值稳定性和决策效率上的不足,该文基于代数关系描述和互补约束理论构建了配电网故障区段定位的互补约束新模型,其优势在于:1)避免了对群体智能算法的过分依赖,可采用数值稳定性好的梯度算法优化求解;2)利用互补约束条件将离散变量松弛为连续变量,降低了故障定位问题决策时的复杂性。在此基础上,提出基于扰动因子的故障定位模型光滑化求解算法。仿真表明,新模型和决策算法不仅能够实现馈线故障区段的准确高容错性辨识,且进行优化决策时具有数值稳定性好、优化效率高的优点,在大规模配电网故障定位中有良好的应用前景。Fast and exact feeder fault location method plays an important role in enhancing reliability and self-healing of distribution network.Logic relationship based conventional indirect fault location model and method has the drawbacks of excessive reliance on swarm intelligence algorithm in optimization computation,numerical optimization instability and low decision-making efficiency.In order to overcome the above shortcomings,on basis of algebra relationship description and complementary theory,a novel complementarity constraints fault location model is proposed as follows:1min()()1,0[(1),(2),,()],[(1),(2),,()],0,,i N S i N N f KB x x x NκκκN=?=???+=⊥=?==?≥∈∈?X∑X X X X X XκκκκRκR(1)Because the feasible points of the above complementarity constraints model can not satisfy the nonlinear programming constraint specification,the optimal solution can not be obtained by using the nonlinear programming to satisfy the Karush-Kuhn-Tucker(KKT)condition.In order to solve the novel fault location model effectively used by nonlinear programming directly,the Fischer-Burmeister auxiliary function with the perturbation factor is used to transform the complementarity constraints fault location model into a continuous smoothing model,which can satisfy the B-stability point.The smoothing model for fault location with complementarity constraints can be expressed as:212 2 2min(,,)()()()()11 2 0()()0[(1),(2),,()][(1),(2),,()][(1),(2),,()],0,N i N N F f i f x x x N N Nφφεφκκκεεε=?=+??=??+=??-++=??=?=?=??=?≥??∈∈?∑X X X XεX XκεX XκεεεκκεκRεR(2)In this model,the feasible point satisfies the nonlinear constraint specification,which can be solved by nonlinear programming directly.When the value of the perturbation factor tends to zero and the KKT extremum condition is established,the optimal decision vector of the fault location model can be obtained,so that the feeder fault section can be found.The correctness and effectiveness of the fault location model with complementarity constraints are verified by(sequence quadratic program)SQP in Matlab2010 a simulation platform.The simulation study shows that:1)The novel model of distribution network fault location based on the theory of complementarity constraints can effectively reflect the correlation characteristics between the causal devices,which can accurately locate the fault section of the feeder fault,and has high fault tolerance.2)The model is proposed based on relational algebra description modeling,so in optimization decision process can avoid the fault identification model excessive reliance on swarm intelligence algorithm in optimization computation,in which the gradient algorithm with good numerical stability can be used,which has the advantage in numerical stability.3)By through the feeder fault status information complementarity constraints conditions,the fault identification model can be transformed from discrete optimization space to continuous optimization space,which can effectively reduce the complexity of fault location model in optimization decision.4)The smoothing method based on the perturbation factor auxiliary penalty function can improve the non-smoothing characteristics of the complementarity constraints model,which can lead the optimal value to converge to the stable point,so as to accurately locate the feeder fault section.5)The novel fault location model and decision method proposed in this paper can be applied to the feeder fault location problem in large scale distribution network.
