Showing papers on "Routing (electronic design automation) published in 1975"

Vehicle Routing Problems: Formulations and Heuristic Solution Techniques

Abstract: : An essential element of the newspaper logistics system is the allocation and routing of vehicles for the purpose of delivering newspapers on a daily basis. In this paper, the author presents various vehicle routing problems. Formulations defining the mathematical models are discussed in conjunction with several widely-used heuristic solution techniques. The focus is on providing a unified framework for these very difficult combinatorial programming problems.

NOMAD: A printed wiring board layout system

Abstract: The NOMAD (Nonmodular Or Modular Automated Design) system provides computer-aided support for the layout of a wide range of printed wiring board designs. The system may be used to design both highly irregular nonmodular and more uniform modular printed wiring boards. The nonmodular boards usually contain numerous discrete and some digital components, whereas the modular varieties are almost entirely digital in nature. In order to guarantee flexibility and control of the layout process, the NOMAD system was implemented on a minicomputer-based interactive graphics terminal. The interactive graphics environment permits the NOMAD user to guide the PWB layout process through steps such as component placement and interconnection routing. Through the use of interactive display techniques and both heuristic and algorithmic computational aids, the user can complete the layout with NOMAD in a considerably shorter time than with alternative methods. Although the focal point of the NOMAD system is at the graphics terminal, telecommunication facilities are utilized to access large compute-bound component placement programs. Aside from the placement, all other design activities, including automatic routing aids, occur at the graphics computer. Once a printed wiring board layout is complete, facilities are available through NOMAD to obtain a full array of design documentation. This documentation includes artmasters for printed wiring board fabrication, an assembly drawing, a stocklist, schematic drawings, and a drill table.The NOMAD system has been operational since April, 1974. Improvements and enhancements are being made continually in an effort to further increase the cost effectiveness of the system.

The Optimal Routing of Solid Waste Collection Vehicles

Abstract: This note employs a modified multiple traveling salesmen cost matrix to model the routing of solid waste collection vehicles. Two examples are presented to demonstrate the real world applicability of the procedure and the need for more efficient solution techniques. In the first example, a facilities location technique is used in conjunction with the routing model to locate a transfer station.

Queueing network model of interactive computing systems

Abstract: A closed queueing network model with state dependent routing probabilities is developed for the study of interactive computing systems which use swapping as a memory managmnent strategy. An algorithm to obtain an approximate solution of the mathematical model is proposed. Based on meamuements of a dual-processor PDP-10 system, the model is found to be better in predicting the system performance than the classical model without state dependent routing probabilities.

Optimisation et Planification de Réseaux de Télécommunications

Abstract: The problem of minimum cost extension of an existing communication network, over a given time period [0, T], is stated and formulated. A two phase solution method is then described, in which: a) an optimal long-range configuration is sought, assuming static routing all over the period [0, T]; b) the optimal dynamic routing problem is solved by relaxing the fixed routing assumption, and taking into account the results obtained in phase a).

An algorithm for automatic line routing on Schematic Drawings

Abstract: An algorithm has been developed to produce automated line routing for Schematic Drawings. Aesthetics, elimination of manual interventions, reliability and consistency of results were among the primary goals of this development.

Prerouting analysis programs

Abstract: Most people who are involved with routing printed wiring boards have one or more favorite indicators which they use to predict routing success. Generally these indicators are looked at more as an afterthought, however. If the numbers happen to be available, people might look at them, but seldom is there a deliberate attempt to find and analyze them.This paper shows why the process of calculating and checking indicators, called here prerouting analysis, is a profitable task. It further examines what should be measured and shows examples of three analysis programs which have proved quite useful in multilayer board routing, and then gives actual results to substantiate the claim.

The automatic printed wire routing system of BACKIS

Abstract: As the printed wiring density on circuit packs and equipment multilayer boards increases, it becomes increasingly difficult for the unaided human to route the printed wire paths needed to interconnect the terminals constituting an electrical node (i.e., a net). Thus, a large amount of effort has been devoted to providing computer aids to assist the designer with the routing problem. The ultimate aim is to provide an automatic routing system which will achieve complete net connectivity meeting all hardware and electrical constraints. While the system presented here does not completely reach these goals, it does represent one of a series of steps in attempting to achieve it. It does this by providing fast, cost effective routers embodied in a system design which permits the user wide latitude in controlling the routing strategy to be used. This paper discusses the concept of a routing strategy, what strategies may be used, and some comments on what has been found to be an effective strategy.

On the dynamics of a class of optimum routing problems

Abstract: A particular class of routing problems associated with demand actuated transportation systems requires the repeated regeneration of minimum or optimum routes as a part of the more general routing problem. The generation or regeneration of routes by methods other than classical minimum route solutions is discussed. A general system model for processing demands in a demand actuated transportation or routing system is presented and discussed.

Heuristic Methods for Solving Large Scale Network Routing Problems: The Telpaking Problem

Abstract: An approach to a large scale network routing problem with nonlinear cost function is described, along with an example of its application. The approach to the problem involves a multistage construction process. This approach is applied to the telpaking problem. Results are obtained in applying this method to a 53 node sample problem.

Weather routing of ships

Abstract: Ship routing is now an established practice. This article briefly considers the interaction of the various contributing factors, which include meteorology, oceanography, naval architecture and economics, limitations and future applications of weather routing.

Branched path communications apparatus for routing communications signals

Abstract: A path routing arrangement to perform path routing operations for wideband communications between subscriber terminals of a communications system is disclosed. To enable such communications the invention incorporates principles of frequency division to allow communications carriers to share a common transmission path, a plurality of which transmission paths may be selectively defined through a branched path path routing arrangement, desired paths being so defined to allow bi-directional carrier transmission between calling ones and called ones of the subscriber terminals.

Quantitative comparison of routing systems

Abstract: A study is made of various systems used to route interconnections on printed-circuit boards, and methodsof assessing their quality are proposed. Two novel routing systems are suggested for different operating environments. A large number of randomly generated boards are routed by the new and by the existing methods, thus enabling a statistical comparison to be made. A basic theory of board interconnection is developed, aiding the prediction of routing-system behaviour. Through this theory and numerical experiment, some alternative systems are compared quantitively for the first time.

A heuristic procedure for distributed computer system design

Abstract: A model of a distributed computer system for transaction processing is described. The system configuration problem is formulated as a problem of determining transaction allocation, routing, processor allocation and line allocation to satisfy certain performance requirements and design constraints. A heuristic design procedure is described. Topics for further investigation are discussed.

Specification and preliminary design of an array processor

Abstract: The design of a computer suited to the class of problems typified by the general circulation of the atmosphere was investigated. A fundamental goal was that the resulting machine should have roughly 100 times the computing capability of an IBM 360/95 computer. A second requirement was that the machine should be programmable in a higher level language similar to FORTRAN. Moreover, the new machine would have to be compatible with the IBM 360/95 since the IBM machine would continue to be used for pre- and post-processing. A third constraint was that the cost of the new machine was to be significantly less than that of other extant machines of similar computing capability, such as the ILLIAC IV and CDC STAR. A final constraint was that it should be feasible to fabricate a complete system and put it in operation by early 1978. Although these objectives were generally met, considerable work remains to be done on the routing system.