Bi-criteria solid transportation problem with substitutable and damageable items in disaster response operations on fuzzy rough environment

Successful planning and scheduling of relief operations play a key role in saving lives and reducing damage in disasters. These disaster operations involve a variety of challenging multi-objective optimization problems, for which soft computing methods are well suited. In this investigation, relief materials and human resources are transported from some distribution centers (DCs) to some delivery points (DPs) through conveyances. The objectives are to minimize both total cost and time for transportation. Some particular models for (a) substitutable items (b) damageable items and (c) safety Factor have been derived. To convert bi-criteria solid transportation problem into a single objective problem, three different techniques (i) Fuzzy interactive satisficing method, (ii) Global Criterion Method and (iii) Convex Combination Method are used. Then the reduced single objective problem is solved by a non-linear optimization technique – Generalized reduced gradient method using LINGO-14.0. The models are illustrated through some numerical examples and optimal results are presented in tabular forms.     

城市空间互补与城市交通问题

聚集效应主要决定于城市区域空间之间的互补性,而与土地价格不存在互为因果的关系.城市区域空间互补性越强,聚集经济越大,资源空间布局越有效率,城市通勤距离也越短.由此才可以形成有效率的城市多中心空间形态.大都市交通问题的根源在于城市资源空间布局的非互补性.     

关于货物运输方案优化的探究

货物运输在运输领域是一个重要的范畴,运输方案的选择对于货物的合理化运输具有重要意义。     

上海市民出行效率调查与分析

采用现场调查、电话调查、网上问卷相结合的方式对上海市民的出行效率进行调查与分析,并针对调查结果提出了相关政策建议。     

Feasibility on the integration of passenger and freight transportation in rural areas: A service mode and an optimization model

Public transport operators in rural areas have been under pressure from weak profitability and emission issues. At the same time, scattered demand for transport has been preventing logistics systems from reaching the last mile in residential areas. Multimodal transport can synergistically integrate passenger and freight demand, increase transportation network coverage, and reduce the cost of transportation, while demand-driven services improve the flexibility and reliability of operational decisions. Therefore, this paper proposes a demand-driven passenger-and-freight-integration service (DDPFIS) mode. From the perspective of routing decisions, a new mixed-integer linear programming model based on the green vehicle routing problem is formulated to assist public transport operator’s complex decision-making. In the proposed model, vehicle capacity is fully utilized through a combination of passenger and freight demand so that optimal decisions are made about vehicle routing. Numerical experiments are designed and conducted based on realistic instances with the results indicating that: the DDPFIS mode enables effective integration of different demands, leading to high-level vehicle capacity utilization and cost reduction; and compared with two conventional models of vehicle routing problems, the proposed model achieves lower fuel consumption and cost for all problem sizes. In addition, some important management insights are provided, e.g., a greater proportion of integrated service nodes is not necessarily better; and it is more suitable to provide a service for rural residents who are relatively insensitive to time.     

铁路集装箱运输现状分析与建议

文章通过对铁路集装箱运输的现状及存在问题进行分析,提出了合理规划建设集装箱运输网络、建设集装箱中心站和物流中心、开行铁路集装箱班列和双层集装箱列车、推动集装箱多式联运的发展、提升服务质量、拓宽融资渠道等实现铁路集装箱运输跨越式发展的的建议。     

On the generalized principal-agent problem: Decomposition and existence results

This paper addresses the class of generalized agency problems: situations in which adverse selection and moral hazard are jointly present. We present a decomposition of the principal's optimization problem under the first-order approach that sheds light on the interactions between the two types of private information, and also significantly improves tractability. We use the decomposition to (1) provide examples of closed form solutions of the optimal contract, and (2) analyze the existence of optimal contracts. We also show that the first-order approach is valid in generalized agency problems if the production technology satisfies the linear distribution function condition (LDFC) in actions and types. For more general production technologies the Mirrlees-Rogerson sufficient conditions need to be extended to include restrictions on the form of the optimal contract. Received: 11 August 1997 / 26 September 1999     

公共交通建设与城市可持续发展

分析了现有城市交通体系存在的问题和城市交通体系发展的可持续性,认为应在大中城市建设以轨道交通系统为主干的区域性综合公共交通体系,并提出城市交通体系可持续发展的建议.     

长江中下游江海直达运输的现状及发展前景

近年来,随着中国经济的快速发展,能源与建设运输需求与日俱增,为江海直达运输提供了充足货源。文中从长江中下游江海直达运输现状入手,从货源、航道与港口、船型方面分析了长江中下游发展江海直达的条件,结论是长江中下游江海直达运输有广阔的发展前景。     

我国特大城市交通战略的未来走向——京沪城市交通比较与启示

交通政策实践分析表明,京沪两市目前交通实践主要集中于交通供给政策,交通需求政策和空间政策实施力度不够,这与发达国家大城市交通实践形成鲜明对比,也导致了京沪城市交通效率低下.两市交通政策的最大差别在于对个体机动车辆的控制方面,上海通过私家车牌照拍卖,在一定程度上控制了小汽车的增长速度,而北京由于缺乏有效举措导致小汽车过快增长,这一政策差别是两市交通效率差异的主要原因.通过京沪交通比较研究,就我国特大城市交通战略的未来走向提出相应的政策建议,以期为城市交通发展决策提供参考依据.     

小城市的道路交通规划--以山东省沂源县城为例

阐述了道路交通规划对于小城市发展的重要性.通过实地调查分析,发现了我国小城市目前存在的一些交通问题,并以山东省沂源县城为例,提出了若干适应小城市发展的道路交通规划方法.     

城市交通与城市空间结构演变

通过回顾城市交通和城市空间结构的发展演变过程,研究通过城市交通引导城市空间结构健康"生长"的有效途径,提出通过公共交通引导城市发展的TOD模式,以及适合中国特色的和谐城市形态和城市交通.     

战时装备保障的多目标运输问题及其求解

提出了集中考虑时间性，安全性的战时装备保障的多目标运输问题并建立了该运输问题的数学模型。基于一种二次抛物偏大型分布的模糊规划算法，将多目标运输问题转化为单目标运输问题，并通过一种改进的表上作业法求得最做优折衷解。最后给出一个实例， 验证了方法的有效性。     

移动运输数据管理系统的设计与实现

文章论述了物流系统中移动运输数据管理系统的设计与实现,重点论述了如何对顾客提出的在线定单进行及时的响应、如何检查定单状态、如何在物品运输过程中进行追踪等问题。采用的方案是为运送货物的运输工具配备一个GPS装置,从而可以周期性地向卫星报告它们当前所处的位置,产生的数据信息用手持设备通过卫星网络传送到中心数据库服务器。     

轨道交通对中国城市化的意义

目前中国正处在快速城市化的进程中,需要增加城市的数量和人口、经济规模,并大力发展城市群和城市带,同时需要减小地区间的发展差距.因此构筑一个从城市轨道交通、城际轨道交通到跨区域的高速铁路这一不同层次的结构完善的覆盖全国的轨道交通体系,将有利于促进城市化,为全国广大人民群众提供快捷、舒适、准时、安全的交通保障,并为在全国范围内建设和谐社会做出重大贡献.     

Optimal distribution of the injured in a multi-type transportation network with damage-dependent travel times: Two metaheuristic approaches

We study a location-allocation-routing problem for distribution of the injured in a disaster response scenario, considering a three-type transportation network with separate links. A circle-based approach to estimate the impacts of the disaster is presented. After formulating relations for computing the percentage of the injured, the destruction percentage and the damage-dependent travel times, the problem is formulated as an integer nonlinear program. We utilize a genetic algorithm and a discrete version of the imperialist competitive algorithm for solving large problems. An empirical study focused on earthquakes in Tabriz, Iran, illustrates applicability of the proposed model and performance of the proposed algorithms.     

装车地直达重载运输发展策略研究

分析了直达重载运输企业与大客户之间的合作博弈关系,得出了两者只有相互合作,使车流与货流能够统筹安排,紧密联系配合,才能取得双赢的结论。还分析了装车地直达重载运输的规模经济特性,给出了确定最佳开行规模的求解方法,并提出了装车地直达重载运输的规模经济战略的建议。     

A genetic algorithm for the partial binary constraint satisfaction problem: an application to a frequency assignment problem

We describe a genetic algorithm for the partial constraint satisfaction problem. The typical elements of a genetic algorithm, selection, mutation and cross-over, are filled in with combinatorial ideas. For instance, cross-over of two solutions is performed by taking the one or two domain elements in the solutions of each of the variables as the complete domain of the variable. Then a branch-and-bound method is used for solving this small instance. When tested on a class of frequency assignment problems this genetic algorithm produced the best known solutions for all test problems. This feeds the idea that combinatorial ideas may well be useful in genetic algorithms.     

浅谈道路运输企业运营成本控制

文章以道路运输企业成本控制为典型案例进行分析研究,从内、外部环境分析其成本控制的现状,找出道路运输企业成本控制的制约因素,对如何提高运输企业的效率与效益进行了探讨研究,提出了控制道路运输企业成本的措施。