Systolic arrays for Viterbi processing in communication systemswith a time-dispersive channel

The theory and design of systolic arrays for Viterbi processing in communication systems with a time-dispersive time-varying channel is discussed. The architecture, algorithms, and processor elements, for a two-dimensional systolic array are described. The array supports the branch metric computations required for an adaptive Viterbi processor. The array is designed so that computations propagate along the rows of the array, while data symbols propagate along the columns. All interprocessor data flow and connections within the array are nearest-neighbor. The array illustrates how the Viterbi-processor algorithms can be structured to achieve a high degree of computational concurrency. Variations in the array design are described and evaluated in terms of computational resource requirements and utilization and computational throughput. A high-bandwidth memory interface is proposed, and system design considerations are discussed     

Determination of minimum cutting tool paths in the presence of barriers

A software package is described that finds a minimum path tour for traveling salesman problems with barriers or obstructions blocking straight line travel. The package contains modules to (1) determine whether or not nodes (destinations) can be connected by straight lines, (2) find the shortest path between pairs of nodes if barriers are present, and (3) compute the minimum tour to visit all nodes and avoid barriers. The user may choose a tour that minimizes distance or minimizes time of travel. The latter assumes constant accelerations and declerations, and steady state tool velocity. Illustrations and sample calculations are presented. The set of algorithms in the software package is a heuristic although some aspects such as the shortest path calculations are optimal.     

Optimality Criteria for Flowshop Schedules

This article considers the problem of scheduling n jobs on M machines in a flowshop and examines the present formulation of the problem. To understand the true nature of the problem, this article provides economic interpretations of various optimality criteria which are being used for solving the scheduling problem. A general optimization criterion, called minimization of opportunity cost, is proposed for flow-shop scheduling problems and the results of the sensitivity analysis of various optimality criteria are reported which indicate the need to reformulate the scheduling problem.     

Studies on oxychlorination of MoS2 in a fluid bed reactor

Studies on the chlorination kinetics of molybdenum sulfide in the presence of a mixture of oxygen, chlorine, and nitrogen gases have been carried out in a fluidized bed reactor at temperatures of 250 to 350 ° and particle size range of 75 to 200 μm. The reaction rate with respect to surface area of MoS₂ particles as well as the composition of reactant gases has been determined and the specific rate constants evaluated. The oxychlorination of MoS₂ has been determined to be of first order with respect to surface area of particles and the overall reaction is found to be controlled by chemical reaction.     

Multi-standby system with repair and replacement policy

This paper investigates the mathematical model of a system composed of (m + 1) non-identical units—one functioning and m standbys. Each unit of the system has four possible states—normal, partial failure, total failure and repair facility—the last one meaning that the totally failed unit is being attended to at the repair facility where it might be either repaired or eventually rejected and replaced. The normal and partial failure states are up states while the other two are down states. The system breaks down when the (m + 1)th unit after total failure is finally rejected and no standby remains to replace it. Several reliability characteristics of interest to system designers as well as operations managers have been computed. Results obtained earlier are verified as particular cases.     

Bonded wedges with an interface crack under anti-plane shear loading

The primary aim of this paper is to describe an analytical technique which may be used in connection with the general problem of bonded wedges containing radial cracks. The technique consists of the reduction of the related dual integral equations of the problem to a singular integral equation in a systematic manner, and is described by applying it to a relatively simple anti-plane shear problem. The paper also presents the results of various numerical examples and the closed form solution for the special case of two bonded wedges with equal angles and an interface crack.

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Résumé L'objet principal du mémoire est de décrire une technique d'analyse utilisable dans le cas du problème général de secteurs jointifs comportant des fissures radiales. La technique consiste à réduire de manière systématique à une équation intégrale singulière les équations intégrales décrivant le problème; un exemple d'application est donné dans le cas d'un problème relativement simple de cisaillement antiplanaire. L'article présente également les résultats de divers exemples numériques, et la solution de forme fermée que l'on trouve dans le cas particulier de deux secteurs collés ayant un angle au centre égal et une fissure dans leur surface de séparation.

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This work was supported by the National Science Foundation under the Grant GK-11977.