SIMULATION: Transactions of The Society for Modeling and Simulation International

Sachs, Crawford L.

doi: 10.1177/003754977201800108pmid: N/A

Mitchell, Baker A.

doi: 10.1177/003754977201800109pmid: N/A

McLeod, John

doi: 10.1177/003754977201800101pmid: N/A

Ashour, Said; Vaswani, S.D.

doi: 10.1177/003754977201800102pmid: N/A

The purpose of this paper is to report on a study which involves a simulation of a hypothetical job shop with several machines. The investigation employs GASP-II as a computer language. This simulation study is concerned with: (1) testing a new method of assign ing job due-dates and (2) comparing and evaluating the effect of different processing-time distributions on the performance of a number of scheduling rules.The most significant results of this study are:(1) The shortest-imminent-operation rule is superior to others in reducing job lateness and shop flow time (2) The procedure in which the due-date allowance is proportional to the number of operations and workcontent of the jobs has proved to be beneficial in the case of the non-due-date rules (3) The operation of a job shop using the shortest-imminent-operation and slack-per-remaining-number-of-operations rules is degraded when the processing-time distribution having Erlang parameter K equal to 4 or 8. However, per formance is better when K = 8 than when K = 4 (4) The GASP-II package works efficiently for large-size shop problems.

Franklin, M.A.; Strauss, J.C.

doi: 10.1177/003754977201800103pmid: N/A

The motivation for automated programming, setup and checking facilities for analog/hybrid computers is discussed and the problems involved are classified. The problem of providing better offline and online program preparation and debugging facilities for analog and hybrid computation is selected for fur ther development. Following a brief characteriza tion of the problem, the available literature is reviewed in depth. Suggestions for future work in this area are included where appropriate.

Chai, A.S.

doi: 10.1177/003754977201800104pmid: N/A

Ehrenberger, W.; Meinlschmidt, G.

doi: 10.1177/003754977201800105pmid: N/A

Clemence, C.R.

doi: 10.1177/003754977201800106pmid: N/A

Textbook designs of digital systems are often based on classical responses produced by specific closed- loop transfer functions, and offer little assistance to the "analog" engineer who is required to convert a number of analog loops to digital control while maintaining product specifications. To ensure uni form operation of the plant during the conversion, it is desirable to have as little change as possible in the response of individual loops in order to minimize unexpected side effects.This paper describes a simulation procedure which enables the engineer to incorporate the familiar analog concepts of proportional, derivative, and integral modes into the digital software and to identify the mode coefficients with corresponding software variables. Thus the digital controller can be tailored to provide mode emphasis similar to that of the analog device being replaced. The whole sys tem, including the digital software, is simulated by analog means and the gain of each mode is adjusted independently until the desired response is obtained.

Hicks, Philip E.

doi: 10.1177/003754977201800107pmid: N/A