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61.
The present paper introduces an integrated approach to solving the generalized lock scheduling problem. Three interrelated sub problems can be discerned: ship placement, chamber assignment and lockage operation scheduling. In their turn, these are closely related to the 2D bin packing problem, the assignment problem and the (parallel) machine scheduling problem respectively. In previous research, the three sub problems mentioned were considered separately, often using (heuristic) interaction between them to obtain better solutions. A mixed integer linear programming model is presented and applied to instances from both inland locks and locks in a tide independent port. The experiments show that small instances incorporating a wide range of real-life constraints can be solved to optimality. 相似文献
62.
This paper considers a supply chain network with multiple depots and geographically dispersed customers, each of which faces non-constant demand over a discrete planning horizon. The goal is to determine a set of depots to open, the delivery quantities to customers per period and the sequence in which they are replenished by a vehicle fleet such that the total system-wide cost is minimized. To solve it, first we construct a mixed integer program, and then propose a hybrid metaheuristic consisting of initialization, intensification and post-optimization. Results show that the proposed heuristic is considerably efficient and effective for many classical instances. 相似文献
63.
10年前的2005年我国在新颁布的《公司法》中大胆的吸收了西方公司法中的一项重要制度,即公司法人格否认制度。该制度的产生是为了规避在股东有限责任的背景下股东滥用有限责任从而损害债权人的利益的问题。我国企业在进行了公司制的改革后,也同样存在着股东可能滥用有限责任的问题,因此在公司法中规定法人格否认是必须的。但是,从10来的司法实践来看,公司法人格否认制度还没有能够完全发挥其限制股东滥用有限责任,保护无辜债权人的立法目的。本文针对在司法实践中存在的问题,在理论上提出一些建议,以求进一步完善公司法人格否认制度。 相似文献
64.
Alexander Kunith Roman Mendelevitch Dietmar Goehlich 《International Journal of Sustainable Transportation》2017,11(10):707-720
The deployment of battery-powered electric bus systems within the public transportation sector plays an important role in increasing energy efficiency and abating emissions. Rising attention is given to bus systems using fast charging technology. This concept requires a comprehensive infrastructure to equip bus routes with charging stations. The combination of charging infrastructure and bus batteries needs a reliable energy supply to maintain a stable bus operation even under demanding conditions. An efficient layout of the charging infrastructure and an appropriate dimensioning of battery capacity are crucial to minimize the total cost of ownership and to enable an energetically feasible bus operation. In this work, the central issue of jointly optimizing the charging infrastructure and battery capacity is described by a capacitated set covering problem. A mixed-integer linear optimization model is developed to determine the minimum number and location of required charging stations for a bus network as well as the adequate battery capacity for each bus line. The bus energy consumption for each route segment is determined based on individual route, bus type, traffic, and other information. Different scenarios are examined in order to assess the influence of charging power, climate, and changing operating conditions. The findings reveal significant differences in terms of required infrastructure. Moreover, the results highlight a trade-off between battery capacity and charging infrastructure under different operational and infrastructure conditions. This paper addresses upcoming challenges for transport authorities during the electrification process of the bus fleets and sharpens the focus on infrastructural issues related to the fast charging concept. 相似文献
65.
66.
Yacine Rekik 《International Journal of Production Economics》2011,133(1):172-181
The inventory level shown in the Information System contrary to popular belief and assumptions in most academic papers and in spite of the considerable amounts invested in information technology, is often inaccurate. The inventory inaccuracy occurs when the inventory shown in the Information System is not in agreement with the actually available inventory. In this paper, we first describe the major factors generating inventory inaccuracy. Then, we provide situations permitting to manage an inventory system subject to errors. We provide a general framework permitting to model the inventory inaccuracy issue. In particular, we link the inaccuracy issue with the well known random yield problem. The shown link permits us to derive the optimal ordering policy of an inventory framework where demand satisfaction is done based on the inventory records (which are subject to inaccuracies). We also propose an analysis permitting to show the added value of an advanced identification system such as the RFID technology. 相似文献
67.
This paper focuses on the procurement of full truck-load transportation service with the view to ensuring sustainability in transport logistics. The carrier assignment problem (CAP) involved in truck load contract auction is studied using a complete enumeration method and heuristic approach. Performance of both methods is compared in terms of solution quality and computational time based on the results of sample problems considered. Also, the impact of combinatorial bidding on reducing empty haul in real world case is analyzed and environmental sustainability is achieved through reduction in carbon foot print. 相似文献
68.
Xiangdong Xu Anthony Chen Lin Cheng 《International Journal of Sustainable Transportation》2015,9(6):419-430
Various government laws have recently been enacted to alleviate the environmental deterioration of transportation systems. Environmental constraint is a valid means to explicitly reflect various environmental protection requirements imposed by the government. In this paper, we examine the environmentally constrained traffic equilibrium problem (EC-TEP), which is a fundamental tool for modeling and evaluating environmental protection requirements. Specifically, we provide an equivalent reformulation for the EC-TEP. The proposed reformulation adapts the concept of gap function to simultaneously reformulate the nonlinear complementarity conditions associated with the generalized user equilibrium conditions, environmental constraints, and conservation constraints as an equivalent unconstrained optimization problem. This gap function reformulation has two desirable features: (1) it can handle a general environmental constraint structure (linear or nonlinear; link-based or area-based) and a general link and route cost structure, enhancing the modeling adaptability and flexibility; (2) it is smooth and unconstrained, permitting a number of existing efficient algorithms for its solution. A gradient-based solution algorithm with a self-regulated averaging stepsize scheme is customized to solve the reformulated unconstrained optimization problem. Numerical examples are also provided to demonstrate the modeling flexibility of the proposed EC-TEP reformulation. 相似文献
69.
我国高科技风险投资业存在的问题及对策 总被引:1,自引:0,他引:1
目前,我国高风险投资业存在诸多问题,应借鉴发达国家先进经验,尽快完善法律、法规及制度的建设,采取政策鼓励、开拓风险资本来源、引进风险投资人才、提供最佳撤出渠道及加强行业协会建设等策略,促进我国风险投资业的健康发展。 相似文献
70.
Melvin F. Shakun 《Group Decision and Negotiation》1996,5(4-6):305-317
Evolutionary Systems Design (ESD) is a universal general problem solving, formal modeling, design framework for purposeful
complex adaptive systems (PCAS) and processes, i.e., task-oriented group processes. These processes constitute policy making,
group decision, negotiation, and multiagent problem solving with human and/or artificial agents. ESD is also a framework for
computer group support systems (GSS) that support these processes. The ESD general framework can be applied to define and
solve specific problems. In this article the ESD framework is presented and illustrated by example. The article provides background
for ESD computer implementations discussed in two other related articles (Lewis and Shakun 1996; Bui and Shakun 1996). 相似文献