考虑多重覆盖的应急设施多级协同布局鲁棒优化

应急设施的合理布局是灾后实现物资高效、公平和稳定供应的重要保障.针对突发自然灾害的不确定性,研究基于多重覆盖的应急设施多级协同布局鲁棒优化问题.首先,提出多级设施选址下的多重覆盖水平函数,以最小覆盖水平和期望总成本最优为目标,建立应急设施多级协同选址双目标优化模型;其次,应用基数不确定集和p-鲁棒方法构建两类鲁棒优化模型,分别研究场景内不确定需求和随机场景对设施布局的影响;最后,以湖南省救灾备荒种子储备库选址为例进行实证分析,验证所提出优化模型的有效性.研究结果表明:多级协同布局相比传统布局方案更具优势;鲁棒优化模型能够有效应对不确定情形和随机场景下的物资需求;决策者的风险偏好程度和预算水平对设施协同布局有重要影响,需对二者进行综合权衡.     

易腐品多周期闭环物流网络鲁棒优化模型

针对不同周期的易腐品需求与退货不确定性问题,构建了易腐品多周期闭环物流网络,并设计了对应的混合整数线性规划（MILP）模型,以实现最低系统总成本、最佳设施选址以及最优配送车辆运输路径的决策。为有效规避不确定参数的影响,采用基约束鲁棒方法,将模型中的部分清晰约束转换为鲁棒对应式。以上海市果蔬农产品企业为实例,通过遗传算法对模型进行求解。结果表明,相对单周期而言,多周期系统具有动态性、系统成本更低的优点,同时通过不确定预算参数的变化分析,验证了鲁棒模型的可行性与有效性,进而为不确定环境下构建多周期闭环物流网络及降低系统成本提供了借鉴。     

碳税影响下再制造物流网络鲁棒优化模型

为了解决不确定环境下低碳再制造物流网络设计的问题,在政府征收企业碳税的情况下,综合考虑网络中再制造产品需求量和废旧产品质量的不确定性以及设施选址和节点间运输路线的决策问题,采用鲁棒优化方法,以碳税成本和物流成本之和最小化为目标,建立了再制造物流网络鲁棒混合线性规划模型。通过案例验证了鲁棒模型的可行性,就税率和不确定参数的变化进行分析,表明鲁棒模型的决策具有实用性和有效性。     

时空需求下的电动汽车充电设施选址优化模型

针对电动汽车充电站布局位置不合理、充电利用率较低等问题，提出了一种时空需求下的充电设施选址优化模型STDM。通过对电动汽车出行数据的时空分布特征进行挖掘，结合电动汽车的出行与充电行为构建充电需求预测模型来获得区域内时空需求分布；采用基于时空统计量的方法获取需求热点区域，考虑到充电站服务覆盖问题，定义充电覆盖率作为模型评估参数；在此基础上从用户角度与运营和社会角度综合构建电动汽车到站距离成本、充电站建设运行成本和碳排放成本的优化模型。最后通过实际数据验证模型的可行性和有效性。结果表明，模型得出了区域内12个充电站的选址方案降低综合成本，同时确定充电站的布局位置与充电桩数量；此外，采用所提方法得到的模型选址结果相比于其他文献方法能够有效缩短电动汽车到站距离，并提高到站覆盖率。     

基于Prim-DMGA算法的闭环供应链网络鲁棒优化研究

针对不确定环境下的闭环供应链网络优化问题,在需求不确定及设施中断风险的条件下,基于鲁棒对等优化方法建立了一种以闭环供应链网络总成本最小为目标的鲁棒优化模型,以解决供应链网络中的不确定性问题,并提出了Prim-DMGA。首先基于Prim算法得到高质量的初始种群,其次让路径规划方案和设施选址方案在两层自适应GA的不断反馈中达到最优。实验结果表明,Prim-DMGA得到的目标函数值优于单层Prim-MGA与传统GA,且在求解大规模算例时,求解结果优于CPLEX软件。研究结论表明,Prim-DMGA能以较少的计算时间获得质量更优的解,鲁棒优化模型可以有效减少不确定因素带来的不利影响,提高闭环供应链网络的鲁棒性能。     

鲁棒线性优化问题研究综述

鲁棒优化（ＲＯ）是从计算复杂性的角度研究不确定优化模型鲁棒最优解的数学方法．从单阶段鲁棒优化和多阶段鲁棒优化两个方面对鲁棒线性优化（ＲＬＯ）理论的研究进展进行综述,前者的研究主要基于不同形式的不确定集合,后者的研究则基于前者的方法．研究多阶段不确定决策中决策变量受不确定参数实现值影响的情况,其核心是影响函数连续时的仿射可调鲁棒对应模型和函数离散时的有限适应性模型．最后对ＲＬＯ 的研究前景作了展望．     

不确定情况下考虑设施失效的鲁棒选址问题研究

当突发事件发生后,道路状况,物资需求和其他无法预知并控制其变化的外部因素,导致决策者难以制定出及时、有效的救援方案。本文考虑到设施失效的情况,构建了同时考虑运输、库存和失效费用的选址模型,在此基础上构建了相应的需求不确定的鲁棒优化模型并转换成鲁棒对应模型。数值例子表明鲁棒优化的选址模型相比于相应的确定性选址模型,应急物资中心数量更少,服务覆盖的范围更大,库存量增大,需求满足率更高,为决策者提供更佳的决策方案,从而增强了应急系统的可靠性,提高应急救援的社会效益。     

鲁棒线性优化问题研究综述

鲁棒优化（ＲＯ）是从计算复杂性的角度研究不确定优化模型鲁棒最优解的数学方法．从单阶段鲁棒优化和多阶段鲁棒优化两个方面对鲁棒线性优化（ＲＬＯ）理论的研究进展进行综述,前者的研究主要基于不同形式的不确定集合,后者的研究则基于前者的方法．研究多阶段不确定决策中决策变量受不确定参数实现值影响的情况,其核心是影响函数连续时的仿射可调鲁棒对应模型和函数离散时的有限适应性模型．最后对ＲＬＯ 的研究前景作了展望．

     

不确定旅行商问题的鲁棒模型与算法

考虑到不确定参数在旅行商问题(TSP)中广泛存在,在Bertsimas鲁棒离散优化理论的框架下,建立了不确定旅行商问题的鲁棒优化模型,并按转换规则将鲁棒模型转换为鲁棒对等模型。给出了一种求解旅行商问题的基于Prufer数编码的单亲遗传算法,与求解该类问题的传统遗传算法相比,该算法缩减了染色体长度,避免了传统交叉和变异操作破坏染色体可行解的缺陷。通过算例验证,表明该算法有较高的求解效率,所建立的鲁棒模型在不确定环境下能得到较好的鲁棒解。     

基于库存切换的不确定动态供应链网络系统模糊鲁棒控制

研究基于库存切换的不确定动态供应链网络系统的鲁棒运作问题.首先,建立含有系统参数不确定和顾客需求不确定的动态供应链网络的离散T-S模糊模型;然后,提出一种新的模糊鲁棒控制策略,该控制策略不仅可以有效遏制子系统切换时产生的较大波动,而且可以抑制不确定因素对供应链网络的影响,进而保证供应链网络在不确定环境下鲁棒稳定;最后,通过仿真实例表明了所提出模糊鲁棒控制策略的有效性.     

Battery swap station location-routing problem with capacitated electric vehicles

In this paper, we present an electric vehicles battery swap stations location routing problem (BSS–EV–LRP), which aims to determine the location strategy of battery swap stations (BSSs) and the routing plan of a fleet of electric vehicles (EVs) simultaneously under battery driving range limitation. The problem is formulated as an integer programming model under the basic and extended scenarios. A four-phase heuristic called SIGALNS and a two-phase Tabu Search-modified Clarke and Wright Savings heuristic (TS-MCWS) are proposed to solve the problem. In the proposed SIGALNS, the BSSs location stage and the vehicle routing stage are alternated iteratively, which considers the information from the routing plan while improving the location strategy. In the first phase, an initial routing plan is generated with a modified sweep algorithm, leading to the BSSs location subproblem, which is then solved by using an iterated greedy heuristic. In the third phase, the vehicle routes resulting from the location subproblem are determined by applying an adaptive large neighborhood search heuristic with several new neighborhood structures. At the end of SIGALNS, the solution is further improved by a split procedure. Compared with the MIP solver of CPLEX and TS-MCWS over three sets of instances, SIGALNS searches the solution space more efficiently, thus producing good solutions without excessive computation on the medium and large instances. Furthermore, we systematically conduct economic and environmental analysis including the comparison between basic and extended scenarios, sensitivity analysis on battery driving range and efficiency analysis about the vehicle emissions reduction when EVs are used in the logistics practice.     

换电站对配网无功优化的影响研究

换电站作为电动汽车的主要充电基础设施,随着电动汽车的普及也将大规模建设。为了分析大规模换电站接入配网对无功优化产生的影响,提出了以换电站充电负荷对配网无功优化的影响为研究对象。首先基于力帆换电站的历史数据分析了换电站充电负荷影响因素的分布规律,然后采用蒙特卡洛仿真模拟建立了换电站的充电负荷模型。还建立了配网无功优化的数学模型,采用禁忌搜索算法求解数学模型。考虑到换电站充电负荷为概率模型,采用基于蒙特卡洛模拟的随机潮流进行潮流计算。最后从换电站充电负荷的渗透率角度分析了对配网无功优化的影响,得出的结论是换电站充电负荷的渗透率为一定值时,相比未接入换电站充电负荷的情况,可以降低电容器的投切次数,延长电容器的使用寿命。     

Traffic Equilibrium and Charging Facility Locations for Electric Vehicles

This study investigates the electric vehicle (EV) traffic equilibrium and optimal deployment of charging locations subject to range limitation. The problem is similar to a network design problem with traffic equilibrium, which is characterized by a bi-level model structure. The upper level objective is to optimally locate charging stations such that the total generalized cost of all users is minimized, where the user’s generalized cost includes two parts, travel time and energy consumption. The total generalized cost is a measure of the total societal cost. The lower level model seeks traffic equilibrium, in which travelers minimize their individual generalized cost. All the utilized paths have identical generalized cost while satisfying the range limitation constraint. In particular, we use origin-based flows to maintain the range limitation constraint at the path level without path enumeration. To obtain the global solution, the optimality condition of the lower level model is added to the upper level problem resulting in a single level model. The nonlinear travel time function is approximated by piecewise linear functions, enabling the problem to be formulated as a mixed integer linear program. We use a modest-sized network to analyze the model and illustrate that it can determine the optimal charging station locations in a planning context while factoring the EV users’ individual path choice behaviours.     

需求不确定的设施选址与多阶段生产鲁棒模型研究

选址决策是长期的战略性问题,在选址问题中考虑不确定性因素至关重要。假设需求取值于有界的对称区间,在设施选址与多阶段生产问题中提出一种新的鲁棒性方法,通过调节不确定预算,来权衡解的鲁棒性与系统成本之间的关系。该鲁棒性问题不仅能够转化成线性规划,而且可以计算出设施的最低服务水平。最后,通过随机生成数值算例,得出不同鲁棒性水平下拓扑结构截然不同的设施网络,并分析了服务水平与成本之间的权衡关系,同时对需求的不确定水平作了敏感性分析。     

Hybrid cost and time path planning for multiple autonomous guided vehicles

In this paper, simultaneous scheduling and routing problem for autonomous guided vehicles (AGVs) is investigated. At the beginning of the planning horizon list of orders is processed in the manufacturing system. The produced or semi-produced products are carried among stations using AGVs according to the process plan and the earliest delivery time rule. Thus, a network of stations and AGV paths is configured. The guide path is bi-direction and AGVs can only stop at the end of a node. Two kinds of collisions exist namely: AGVs move directly to a same node and AGVs are on a same path. Delay is defined as an order is carried after the earliest delivery time. Therefore, the problem is defined to consider some AGVs and material handling orders available and assign orders to AGVs so that collision free paths as cost attribute and minimal waiting time as time attribute, are obtained. Solving this problem leads to determine: the number of required AGVs for orders fulfillment assign orders to AGVs schedule delivery and material handling and route different AGVs. The problem is formulated as a network mathematical model and optimized using a modified network simplex algorithm. The proposed mathematical formulation is first adapted to a minimum cost flow (MCF) model and then optimized using a modified network simplex algorithm (NSA). Numerical illustrations verify and validate the proposed modelling and optimization. Also, comparative studies guarantee superiority of the proposed MCF-NSA solution approach.     

考虑用户选择偏好的电动汽车充电站规划研究

在国家大力发展新能源汽车的过程中,充电问题一直阻碍着电动汽车的发展,充电基础设施尤其是快速充电站的规划和建设尤为重要。大规模发展电动汽车（electric vehicle,EV）的关键是根据用户的充电选择偏好,建立完善的充电基础设施,减少用户的里程焦虑,彻底解决充电不方便的问题。在考虑了各方面社会因素并确定一定数量的候选节点背景研究的基础上,提出了一种双目标规划模型,在满足需求、距离、容量等约束条件下,分析了建设充电站总成本和充电覆盖范围之间的关系,寻找最优的充电站建设方案,并以A城市B区为例,通过多目标粒子群算法进行求解,求出充电站的最佳节点和数量。用不同算法进行求解,通过对结果进行分析比较,表明多目标粒子群算法（MOPSO）在求解双目标问题时更具有实际意义。     

引导电动汽车用户驾驶行为的充电导航策略

电动汽车充电导航便于用户合理选择充电站,降低用户自身的时间成本和经济成本,缓解配电网端的负荷压力.在电网分时电价的基础上,考虑电动汽车充电路径的选择与车主的驾驶行为密切相关,通过对电动汽车的负荷设备分类建模,根据不同设备类型的重要程度及用户的电动汽车实际工况和地形因素,利用遗传算法分析最佳出行路径,提出以时间成本与经济成本之和最优为目标,引导用户驾驶行为的充电导航策略.在20kmtimes10km含3个充电站的区域内,通过3种不同充电导航策略仿真结果对比,验证所提出的导航策略的可行性和有效性.     

基于二次聚类的大规模电动汽车有序充电调度策略优化

针对大量电动汽车无序充电造成的充电站利用率不均衡问题,提出一种大规模电动汽车有序充电调度策略。首先,以电动汽车充电需求的位置为聚类指标,借助归一化相似度进行层次聚类和基于K-means算法的二次划分,以实现属性相似的电动汽车的汇聚。进一步地,通过Dijkstra算法获取电动汽车到达各个充电站的最优路径,以充电站内电动汽车的均匀分配和电动汽车充电路程最短作为目标函数,构建了基于电动汽车聚类的充电调度模型,通过遗传算法求取最优解。与未进行电动汽车聚类的充电调度策略进行的仿真对比实验结果表明,在车辆较多时所提方法的计算时间可减少一半以上,具有较高的实用性。     

Extensions to emergency vehicle location models

This paper is concerned with extending models for the maximal covering location problem in two ways. First, the usual 0–1 coverage definition is replaced by the probability of covering a demand within the target time. Second, once the locations are determined, the minimum number of vehicles at each location that satisfies the required performance levels is determined. Thus, the problem of identifying the optimal locations of a pre-specified number of emergency medical service stations is addressed by goal programming. The first goal is to locate these stations so that the maximum expected demand can be reached within a pre-specified target time. Then, the second goal is to ensure that any demand arising located within the service area of the station will find at least one vehicle, such as an ambulance, available. Erlang's loss formula is used to identify the arrival rates when it is necessary to add an ambulance in order to maintain the performance level for the availability of ambulances. The model developed has been used to evaluate locations for the Saudi Arabian Red Crescent Society, Riyadh City, Saudi Arabia.     

A network transformation heuristic approach for the deviation flow refueling location model

In the early stages of development, alternative-fuel vehicles will tend to have shorter driving ranges than conventional vehicles, and the availability of stations will be limited. Given these conditions, it is important to consider the willingness of drivers to deviate to some extent from their shortest paths in order to refuel their vehicles and complete their trips. Previously, we proposed the deviation-flow refueling location model (DFRLM) for locating a given number of refueling facilities to maximize the total alternative-fuel vehicle flows that can be refueled by drivers traveling on or deviating from their shortest paths. On a real-world problem, however, the large number of possible deviations from each path and of combinations of facilities that can cover each path would make it extremely difficult to generate and solve the mixed-integer formulation. This paper develops heuristic algorithms for the DFRLM that overcome this difficulty through network transformation. Specifically, a greedy heuristic constructs and edits an artificial feasible network in which each node represents a station, origin, or destination, and each arc represents a feasible path between two nodes given the assumed driving range of vehicles. At each step of the greedy and greedy-substitution algorithms, the feasible network is edited and a shortest path algorithm is run, which determines whether each origin–destination round trip can be completed. This method allows any possible detour to be taken (up to some user-defined maximum) while also ensuring that drivers take the smallest possible detour. Computational experiments on a simple network and a real-world network for Florida show the heuristics to be efficient in solving the problems. Comparisons between the results of the DFRLM and the FRLM indicate that taking driver deviations into account in the model can have a significant effect on the locations chosen and demand covered.