Digital Simulation of Continuous Systems

Chu, Yaohan; Lannus, Arvo

doi:10.1149/1.2407313

Cited by 15 publications

(3 citation statements)

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“…The convenience arises because a better initial guess can be made for xl(t = 6), x2(t = 6) than for al(t = 0), a2(t = 0) since x and x2 are physically real variables. 1 The FORTRAN coding for SUBROUTINE EQUATN for this example is given in Figure 9 and the detailed numerical solution results are given in Figure 10.…”

Section: The Optsim Programmentioning

confidence: 99%

An interactive digital simulation and optimization package: FORTRAN programs MINISIM and OPTSIM

Roach

Chow

1975

SIMULATION

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After completing a PhD in chemical engineering at Adelaide University John R. Roach worked in the chemical industry as a design development engineer for four years. This work included the simulation of a bulk-product distribution network. He left industry to lecture in the field of process design and industrial economics. His current simulation interests include control systems, chemical reactor systems, and a novel pneumatic materialshandling system for large payloads.EE-PAN CI-IOW hails from Malaysia. He graduated with a BE (Honors) degree in chemical engineering from the University of Adelaide in December 1972. After having worked for one year as a graduate research assistant at the University's Chemical Engineering Department, he is currently engaged in full-time postgraduate studies in the department.ABSTRACT MINISIM is a general-purpose interactive digital simulation program which is written in FORTRAN and is suitable for both interactive and batch use. The program currently utilizes a fixed-step 4th-order Runge-Kutta integration algorithm. The program has proved to be suitable as a replacement for an analog computer in both teaching and research activities. OPTSIM is an extension of MINISIM that permits optimizing simulated systems automatically while making use of the MINISIM integration routines. The same problem-description subroutine ( SUBROUTINE EQUATN ) may be used with either MINISIM or OPTSIM. Detailed examples are given of the simulation and optimization of a control system and also of the solution of a two-point boundary-value optimization problem . BACKGROUNDDigital simulationl'2'3'4 has become a widely accepted numerical tool for the analysis of complex continuous processes described by differential equations.The programs discussed in this paper were written in response to a need for a simple, easy-to-use, interactive digital simulation package which could be used for other simulation and optimization studies. In contrast to the large-scale batch simulation languages such as MIMIC,' 1 CSMP,l and DARE IIIB,2 the programs offer hands-on features analogous to those of an analog or hybrid computer.To use either MINISIM or OPTSIM, which is an extension of MINISIM, all that the user must provide is a FORTRAN subroutine (SUBROUTINE EQUATN) which describes his problem by a set of first-order differential equations. All normal algebraic operations may be carried out, and the package also provides standard subroutines for time delays and a lookup table for use as an arbitrary-function generator. SUBROUTINE EQUATN is completely compatible with both MINISIM and OPTSIM.

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Section: The Optsim Programmentioning

confidence: 99%

An interactive digital simulation and optimization package: FORTRAN programs MINISIM and OPTSIM

Roach

Chow

1975

SIMULATION

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“…In order to give a mathematical expression for the periodicity of the waveform, the angle b = 2 ~ pi ~ j is utilized, where j = int (awl2 -pi) is the cycle number. In general, periodic excitations of arbitrary waveforms may be generated by using a counter or logical control variables [6]. Designating by a1 (=1.884955592 rad, taken from [13]) the angle at which the rise portion begins, and by a2 (=4.39822971E, rad, taken from [13]) the angle at which the return portion finishes for the initial cycle, we can define the following relationships: and the equivalent equations in each zone for the cam displacement, cam velocity, and cam acceleration, are respectively:…”

Section: Introductionmentioning

confidence: 99%

Determination of the Toss Speed for an Automotive Valve-Gear System

Méndez-Adriani

1993

SIMULATION

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This research presents an improved lumpedparameter model that combines favorably its simplicity and precision to represent appropriately an automotive valve-gear system, by means of the inclusion of a fluidic pressure element within the modeling of the hydraulic lifter, and by considering the hysteretic behavior of the pushrod under cyclic loading. Realistic values have been chosen for the parameters of this cam-follower mechanical system, and the checking of this modified mathematical model has been accomplished by means of a qualitative comparison with other models previously conceived, and with previous experimental results obtained from an automobile engine. The digital computer simulation allows the determination of the cam speed for which the valve toss occurs, whose value is of fundamental importance in evaluating the design of automotive cam mechanisms.

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“…Alternately, some problems yield to numerical solutions or analog simulation. With the recent proliferation of large, fast digital computers, digital simulation has become popular for the solution of a number of complex problems [1]. This paper will present a broad overview of digital simulation and modeling and will, hopefully, suggest to the reader other applications of this technique.…”

Section: Introductionmentioning

confidence: 99%