It is considered here for an improved ant algorithm to minimize the delivery time of VRP （Vehicle Routing Problem） in distribution center. Firstly VRP which objective is to minimize the delivery time is given, then ...It is considered here for an improved ant algorithm to minimize the delivery time of VRP （Vehicle Routing Problem） in distribution center. Firstly VRP which objective is to minimize the delivery time is given, then the optimal vehicle distributionroute-division approach of distribution center for given customer array is defined, and the ant colony algorithm for VRP with objective to minimize the delivery time is presented. The research of this paper is based on the information and application case of tobacco network in Hangzhou city. By investigating, we created two different system models. One is division of distribution route of distribution center, and the other is optimization of single vehicle route. The computational example tests and verifys the solution.展开更多
文摘文章研究不同频点的无电离层组合模型中时间群延迟(time group delay,TGD)和差分码偏差(differential code bias,DCB)对定位结果影响的差异,给出了北斗卫星导航系统(BeiDou Navigation Satellite System,BDS)双频/三频无电离层组合TGD和DCB改正模型,利用IGS测站数据进行标准单点定位(standard point positioning,SPP)和精密单点定位(precise point positioning,PPP)实验。实验结果表明:对于SPP,定位精度平面方向小于5 m,U方向小于10 m,定位精度提升显著且精度改正为m级,经模型改正的平面方向精度提升大于70%,U方向精度提升大于28%,其中DCB改正效果略优于TGD改正;对于PPP,经模型改正后的定位精度提升并不明显,但加快了滤波的收敛速度;对于PPP,在未经模型改正的情况下,接收机钟差和模糊度参数吸收了绝大部分的误差改正,而对流层延迟参数受到的影响较小。
文摘It is considered here for an improved ant algorithm to minimize the delivery time of VRP （Vehicle Routing Problem） in distribution center. Firstly VRP which objective is to minimize the delivery time is given, then the optimal vehicle distributionroute-division approach of distribution center for given customer array is defined, and the ant colony algorithm for VRP with objective to minimize the delivery time is presented. The research of this paper is based on the information and application case of tobacco network in Hangzhou city. By investigating, we created two different system models. One is division of distribution route of distribution center, and the other is optimization of single vehicle route. The computational example tests and verifys the solution.
