An application of Special Ordered Sets to a periodic milk collection problem

We present an OR-based approach to support a milk collection problem in a special branch of dairy industry. The annual growth of the sector and the continuous imbalance between milk supply and demand, has urged the sector to look for a different approach to their daily milk collection problem. Specific details of the problem environment (i.e., the continuous production on supply level and the delivery conditions on demand level) gave rise to choose for a short- to medium-term planning approach. The proposed decision support system has to be considered as an efficient tool for generating stable milk collection plans which in turn also serves as an effective starting point for the vehicle routing problem. From a computational point of view it turned out that the application of Special Ordered Sets type 1 (SOS1) was very useful. Although it appears from literature that the computational advantage of SOS1 is restricted to supplementary model conditions, this study shows that these conditions are not necessarily needed.     

一个低代价的完全自适应路由器设计

互连网络路由器是ＭＰＰ系统的关键器件，其性能优劣直接影响系统性能，本文在ｍｅｓｈ结构上，针对完全自适应器由算法实现难度较大的问题，在性能、低价和实现复杂性 进行合理折衷，给出了一个代价低、自适应性强的完全自适应路由算法ＬＣＦＡＡ，对传统的虫孔路由切换技术进行改进，提出了弹性虫孔路由切换技术，并采用基于虚通道的综合流控策略，设计了一个简洁高交的完全自适应路由器ＬＦＲ，其逻辑在ＸｉｌｉｎｘＸＡＣＴ的Ｃ     

Provisioning Methods for Bit-Rate-Differentiated Services in Hybrid Optical Networks

This paper addresses the problem of routing and wavelength assignment of bit-rate-differentiated optical services in a hybrid network. Hybrid optical networks are composed of resources, such as fiber links and photonic/electronic switches, that vary in their capabilities and transmission qualities. These networks are also responsible for the realization of optical services with varying quality-of-service (QoS) guarantees. In such networks, it is required to have a cost-effective assignment of the optical and electronic resources to these services in order to maximize the revenue of the network operator. This paper deals with optical services that are defined according to their tolerance to transmission impairments. We first divide the provisioning problem into two phases: (1) routing and (2) wavelength assignment and regeneration reservation. In the routing phase, a set of k-routes are generated to select from in the second phase, where each route optimizes a specific aspect of the problem (e.g., number of hops, maximum accumulated noise, etc.). The second phase, using the information about the resources along each route, attempts at finding the best wavelength allocation on that route such that the signal quality meets the service-level agreement (SLA). The second phase also uses the minimum number of regenerator ports on intermediate nodes for the purpose of wavelength translation and signal clean-up. Comparisons of the above scheme with a probing-based method, reveal substantial enhancements to the blocking performance with a maximum running time increase of 60%. In addition, the use of multiple routes provides higher reduction in the blocking probability over single-routing schemes. Moreover, the proposed, non-pessimistic, provisioning approach has a major impact on reducing the regeneration budget of the network.     

Static and adaptive routing in ISL networks from a constellation perspective

This paper presents and evaluates different routing schemes in a constellation of non‐geostationary satellites. Routing decisions may or may not take into account the state of the network. While taking into account the network state is likely to bring an improvement in both the network utilization and the quality of service, it also makes the routing architecture more complex. This paper proposes to evaluate the advantages and disadvantages of these different design approaches for routing. Copyright © 2002 John Wiley & Sons, Ltd.     

集货送货一体化的物流配送车辆路线问题的标号算法

本文结合实际情况,对具有时间窗约束的集货送货一体化的车辆路线问题进行了研究,针对该问题的特点,采用修正的多属性标号算法对该问题进行求解,并通过C 编程语言实现了该算法,最后用一个示例表明本文的算法是有效的.     

基于混合图的总体布线调整

本文提出了一种基于混合图的总体布线调整方法。混合图是对表示布局的有向图进行一系列精确的顶点分解而产生的。用得到的图模型来表示总体布线信息,从而可以在总体布局优化的同时估计布线对芯片面积的影响,并对总体布线进行调整。由于总体布线是自动更新的,所以布局同时随着布线的调整和模块的移动而改进。本文还提出了多种瓶颈的概念和瓶颈间走线随模块旋转而变化的规律。最后给出的实验结果表明,这种算法在减小芯片面积上获得比较好的结果。     

Uniqueness of the solution for optimal static routing in open BCMP queueing networks

Optimal static routing problems in open BCMP queueing networks with state-independent arrival and service rates are studied. They include static routing problems in communication networks and optimal static load balancing problems in distributed computer systems. We consider an overall optimal policy that is the routing policy whereby the overall mean response (or sojourn) time of a job is minimized. We obtain the routing decisions of the overall optimal policy and show that they may not be unique, but that the utilization of each service center is uniquely determined by the overall optimal policy. We also consider an individually optimal policy whereby jobs are routed so that each job may feel that its own expected response time is minimized if it knows the mean delay time for each path.     

全光通信网技术

本文对全光网的概念和关键技术做了简要说明，并介绍了具有代表性的全光网络，最后对各个网络的技术进行了比较，并同了全光网发展的一些主要障碍。     

车辆路径问题的混合优化算法

讨论了一类车辆路径调度问题(VRP)及其数学模型，并且分析了以遗传算法求解该类问题时的染色体表示和有关遗传操作，然后结合2-opt局部优化算法提出了GA with2-opt算法来求解VRP问题，试验结果说明了该算法的有效性和可行性。     

A flexible adaptive memory-based algorithm for real-life transportation operations: Two case studies from dairy and construction sector

Effective routing of vehicles remains a focal goal of all modern enterprises, thriving for excellence in project management with minimal investment and operational costs. This paper proposes a metaheuristic methodology for solving a practical variant of the well-known Vehicle Routing Problem, called Heterogeneous Fixed Fleet VRP (HFFVRP). Using a two-phase construction heuristic, called GEneralized ROute Construction Algorithm (GEROCA), the proposed metaheuristic approach enhances its flexibility to easily adopt various operational constraints. Via this approach, two real-life distribution problems faced by a dairy and a construction company were tackled and formulated as HFFVRP. Computational results on the aforementioned case studies show that the proposed metaheuristic approach (a) consistently outperforms previous published metaheuristic approaches we have developed to solve the HFFVRP, and (b) substantially improves upon the current practice of the company. The key result that impressed both companies’ management was the improvement over the bi-objective character of their problems: the minimization of the total distribution cost as well as the minimization of the number of the given heterogeneous number of vehicles used.