解决布线过程中通道消失分解、合并问题的一种方法

在 VLSI 积木块布图设计模式中,模块的移动会引起通道图发生变化,影响布线的进行。本文给出了一种布线方法,用此方法可保证:任给一个通道图,只要其 T 形约束图中无约束环,无论模块在布线过程中怎样平行移动,均可按照通道图正常布线。此方法已成功地应用在我们研制的 VLSI 版图 CAD 系统中。本文从理论上给予证明,并给出应用实例。     

Metastrategy simulated annealing and tabu search algorithms for the vehicle routing problem

The vehicle routing problem (VRP) under capacity and distance restrictions involves the design of a set of minimum cost delivery routes, originating and terminating at a central depot, which services a set of customers. Each customer must be supplied exactly once by one vehicle route. The total demand of any vehicle must not exceed the vehicle capacity. The total length of any route must not exceed a pre-specified bound. Approximate methods based on descent, hybrid simulated annealing/tabu search, and tabu search algorithms are developed and different search strategies are investigated. A special data structure for the tabu search algorithm is implemented which has reduced notably the computational time by more than 50%. An estimate for the tabu list size is statistically derived. Computational results are reported on a sample of seventeen bench-mark test problems from the literature and nine randomly generated problems. The new methods improve significantly both the number of vehicles used and the total distances travelled on all results reported in the literature.     

CC榕树网络及其光学实现

利用偏振分光棱镜及一维位相型空间光调制器，作者成功地实现了光学ＣＣ榕树网络，并给出任意输入输出对间的连接控制方式，它具肥能量损耗低，串扰小，结构紧凑及高通道密度等优点。     

Delay performance in stochastic processing networks with priority service

We evaluate the delay performance of an open multi-class stochastic processing network of multi-server resources with preemptive-resume priority service. We show that the stationary distribution of aggregate queue lengths has product form. For each service class we derive explicit expressions for the following stationary performance measures: The mean and, under feedforward routing, the Laplace transform of the delay distribution at each resource. We show that these measures are the same as if the resources were operating in isolation.     

An Augmented Lagrangian Algorithm for Large Scale Multicommodity Routing

The linear multicommodity network flow (MCNF) problem has many applications in the areas of transportation and telecommunications. It has therefore received much attention, and many algorithms that exploit the problem structure have been suggested and implemented. The practical difficulty of solving MCNF models increases fast with respect to the problem size, and especially with respect to the number of commodities. Applications in telecommunications typically lead to instances with huge numbers of commodities, and tackling such instances computationally is challenging.In this paper, we describe and evaluate a fast and convergent lower-bounding procedure which is based on an augmented Lagrangian reformulation of MCNF, that is, a combined Lagrangian relaxation and penalty approach. The algorithm is specially designed for solving very large scale MCNF instances. Compared to a standard Lagrangian relaxation approach, it has more favorable convergence characteristics. To solve the nonlinear augmented Lagrangian subproblem, we apply a disaggregate simplicial decomposition scheme, which fully exploits the structure of the subproblem and has good reoptimization capabilities. Finally, the augmented Lagrangian algorithm can also be used to provide heuristic upper bounds.The efficiency of the augmented Lagrangian method is demonstrated through computational experiments on large scale instances. In particular, it provides near-optimal solutions to instances with over 3,600 nodes, 14,000 arcs and 80,000 commodities within reasonable computing time.     

车辆路径问题(VRP)的一个启发式算法

提出了一个基于分区扫描方法和禁忌算法的车辆路径问题的启发式算法,并用一个例子说明其应用.     

电路交换网络无级路由选择的离散事件模拟方法

讨论了电路交换网络的离散事件模拟，给出了在网络过载、线路中断等不同网络状态下，采用的几种常见的路由选择方法的网络性能，还给出了线路保留数等不同的网络参数对网络的影响。与分析法相比，模拟方法能得到更精确的结果，并可模拟用分析方法无法解决的问题     

Simulated annealing metaheuristics for the vehicle routing problem with time windows

This paper develops simulated annealing metaheuristics for the vehicle routing and scheduling problem with time window constraints. Two different neighborhood structures, the λ-interchange mechanism of Osman and thek-node interchange process of Christofides and Beasley, are implemented. The enhancement of the annealing process with a short-term memory function via a tabu list is examined as a basis for improving the metaheuristic approach. Computational results on test problems from the literature as well as large-scale real-world problem are reported. The metaheuristics achieve solutions that compare favorably with previously reported results.     

Metaheuristics in Combinatorial Optimization

The emergence of metaheuristics for solving difficult combinatorial optimization problems is one of the most notable achievements of the last two decades in operations research. This paper provides an account of the most recent developments in the field and identifies some common issues and trends. Examples of applications are also reported for vehicle routing and scheduling problems.     

基于遗传操作的延迟和度约束的多播路由启发式算法

基于启发式思想的简单性和路径相似性原理，采用遗传算法的交叉和变异操作，提出了一种快速的满足延迟和度约束的最小费用多播路由树的生成算法(DDCMRA)，以解决直接修改延迟约束或者度约束多播路由算法时寻优时间长、并且可能导致部分目的节点因不能满足延迟或者度约束而不能加入多播的问题．仿真结果显示。该算法获得的多播路由树满足延迟和度约束，费用较少，运行时间接近CSPT和RA算法．该算法也为动态多播路由树生成和网络负载平衡提供了一种方法．