The vehicle routing problem (VRP) can be described as the problem of designing the optimal delivery or collection routes from one or several depots to a number of geographically scattered customers, subject to load co...The vehicle routing problem (VRP) can be described as the problem of designing the optimal delivery or collection routes from one or several depots to a number of geographically scattered customers, subject to load constraints. The routing decision involves determining which of the demand s will be satisfied by each vehicle and what route each vehicle will follow in s erving its assigned demand in order to minimize total delivery cost. In this pap er, a methodology for the design of VRP by integrating optimization and simulate d annealing (SA) approach is presented hierarchically. To express the problem of vehicle routing, a new mathematical formulation is first conducted. The objecti ve function involves both the delivery cost and the vehicle acquisition cost wit h load constraints. A heuristic is then proposed to solve this problem by using SA procedure in conjunction with any solution procedure of travelling salesman p roblem (TSP). The initial configuration is arranged as one vehicle route ser ving one customer. The SA searching procedure is then developed to combine custo mer to any one of the vehicle routes existed in the system if the capacity and c ost are attractive. An important concept of this proposed heuristic is that it attempts to minimize total number of vehicle required in the system on the b asis of the fixed cost and the variable cost view points. In addition, this appr oach can be easily adapted to accommodate many additional problem complexities.展开更多
We propose two variants of tailored finite point(TFP)methods for discretizing two dimensional singular perturbed eigenvalue(SPE)problems.A continuation method and an iterative method are exploited for solving discreti...We propose two variants of tailored finite point(TFP)methods for discretizing two dimensional singular perturbed eigenvalue(SPE)problems.A continuation method and an iterative method are exploited for solving discretized systems of equations to obtain the eigen-pairs of the SPE.We study the analytical solutions of two special cases of the SPE,and provide an asymptotic analysis for the solutions.The theoretical results are verified in the numerical experiments.The numerical results demonstrate that the proposed schemes effectively resolve the delta function like of the eigenfunctions on relatively coarse grid.展开更多
文摘The vehicle routing problem (VRP) can be described as the problem of designing the optimal delivery or collection routes from one or several depots to a number of geographically scattered customers, subject to load constraints. The routing decision involves determining which of the demand s will be satisfied by each vehicle and what route each vehicle will follow in s erving its assigned demand in order to minimize total delivery cost. In this pap er, a methodology for the design of VRP by integrating optimization and simulate d annealing (SA) approach is presented hierarchically. To express the problem of vehicle routing, a new mathematical formulation is first conducted. The objecti ve function involves both the delivery cost and the vehicle acquisition cost wit h load constraints. A heuristic is then proposed to solve this problem by using SA procedure in conjunction with any solution procedure of travelling salesman p roblem (TSP). The initial configuration is arranged as one vehicle route ser ving one customer. The SA searching procedure is then developed to combine custo mer to any one of the vehicle routes existed in the system if the capacity and c ost are attractive. An important concept of this proposed heuristic is that it attempts to minimize total number of vehicle required in the system on the b asis of the fixed cost and the variable cost view points. In addition, this appr oach can be easily adapted to accommodate many additional problem complexities.
基金the National Natural Science Foundation of China through NSFC No.11371218 and No.91330203the second author was supported by the National Science Council of Taiwan through NSC 102-2115-M005-005.
文摘We propose two variants of tailored finite point(TFP)methods for discretizing two dimensional singular perturbed eigenvalue(SPE)problems.A continuation method and an iterative method are exploited for solving discretized systems of equations to obtain the eigen-pairs of the SPE.We study the analytical solutions of two special cases of the SPE,and provide an asymptotic analysis for the solutions.The theoretical results are verified in the numerical experiments.The numerical results demonstrate that the proposed schemes effectively resolve the delta function like of the eigenfunctions on relatively coarse grid.
