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doi: 10.1177/003754978003400103pmid: N/A
Nonuniform temperature distributions can greatly affect the operation of semiconductor devices. At present, computer programs using numerical methods can be used to simulate the steady-state or transient response of one- or two-dimensional models of semi conductor devices operating at constant temperature. Recently developed programs allow the steady-state analysis of semiconductor devices under nonisothermal conditions. The transient response, the mode of operation for most high-power semiconductor devices, has not been analyzed for a MOSFET.This paper presents a one-dimensional mathematical model for predicting the nonisothermal behavior of a MOSFET under pulse excitation. Both the transient electrical and temperature responses are shown. Redistribution of voltages and carriers resulting from the differences in the electrical and tempera ture time constants is discussed.
doi: 10.1177/003754978003400104pmid: N/A
Coulomb or dry friction occurs in mechanical systems when nonlubricated surfaces come into sliding contact. The force resulting from Coulomb friction has a magnitude dependent on the contact force and a direc tion opposite to the relative velocity. If the re lative velocity is zero, the Coulomb friction assumes the value, within bounds, to maintain zero velocity. This, of course, presents the opportunity for a variety of equilibrium configurations.This paper presents an overview of the common tech niques for the digital simulation of Coulomb fric tion. All these techniques use the relative velocity to determine the friction force and are therefore flawed since they cannot predict multiple equilibrium positions. By means of an example, this paper shows that modeling Coulomb friction as a function of posi tion rather than of velocity allows multiple equili bria and offers features that are useful in modeling high-friction, low-mass systems.
Pegden, C. Dennis; Gately, Michael P.
doi: 10.1177/003754978003400105pmid: N/A
This paper describes a decision-optimization module for use with SLAM simulation models. When appended to the SLAM software package, the optimization module provides capability for the automatic optimization of decisions with respect to an arbitrary user-defined objective function. The purpose of this paper is to describe the optimization technique and the proce dures required to invoke the module from within a SLAM simulation model. An example illustrating the use of the module to determine the optimum timing of traffic lights is presented.
Niedercorn, John H.; Kalaba, Robert; Kandoole, Benson F.
doi: 10.1177/003754978003400106pmid: N/A
According to orthodox Keynesian economic theory, sig nificant unemployment and inflation should not occur simultaneously (i.e., "stagflation" should not exist) in a highly developed modern economy. However, both have occurred simultaneously in the United States since 1973.This paper describes an economic model being developed to investigate the causes of stagflation; this model includes nonlinearities and discontinuities not in corporated in other macroeconomic models. In its present form the model does not include all the var iables necessary to achieve its purpose, and its parameters and initial conditions have been set at arbitrary "reasonable" values. Much work remains to be done before it can simulate stagflation in the economy of the United States. The responses of the present model to initial conditions leading to stag nation, moderate growth, and high-pressure growth situations are reported and analyzed in this paper.The results obtained by experiments conducted on the model reflect the behavior of an idealized competi tive capitalistic economy with implicitly flexible prices and explicitly flexible interest rates. The model eventually produces full employment and steady growth regardless of the initial conditions used. This behavior implies that the simultaneous occur rence of unemployment and inflation should not exist very long in such an economy.
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