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The electronic analog computer is widely used to simulate most types of automatic control systems, Only a limited amount of work has been reported, however, involving analog computer simulation of sampled-data systems, This is to be expected since such systems are essentially digital in nature. The purpose of the work described in this thesis was to develop methods of simulating various phenomena associated with sampled-data system, The techniques which have been developed are described ad evaluated in the report. In addition, experimental data is presented to illustrate the performance of the various simulation circuits. As an illustration of the techniques which have been developed, the simulation of a representative sampled-data system is described. Data obtained from this simulation is included in the report. / Master of Science

The thesis describes a realization of distributed experimental frame concepts in DEVS-SCHEME, an object-oriented simulation environment. Also discussed, are the design and implementation issues concerning the attachments of frame components to a model in a given model structure. The algorithm for the attachments is derived to set up the model composition and model couplings when needed. An example of a simplified computer system which consists of a CPU, and a memory management (MGMT), is presented to demonstrate how such a system is observed and experimented with under centralized and decentralized experimental frames. A graphical interactive interface is provided to facilitate the attachments of frame components to models. The simulation shows that the theory regarding decentralized experimental frames is correct and feasible. Some prospective research topics and future study activities are also brought up.

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This thesis is concerned with the problem of determining an optimal irrigation policy, that is, an optimal quantity and frequency of irrigation water application. The purpose is to present a solution to this problem using a continuous review model of an inventory system. Initially, the functions of the plant -water -soil system are discussed. This is followed by a review of several existing methods for maximizing crop yield or profit by determining an optimal irrigation policy. Next, the inventory problem is briefly examined. An analogy is drawn between the farmer's problem of determining an optimal irrigation policy and the businessman's problem of determining an optimal ordering policy. Subsequently, a continuous review model of the irrigation system is developed and an example of its use is given.

Well designed experiments can dramatically improve the statistical accuracy of simulation output data and facilitate the statistical analysis. In practice, however, the design of experiments is the most neglected phase of a simulation study. What is needed is good, sound experimental design strategies that can be easily implemented by practitioners. In this dissertation, an experimental design strategy is proposed for finding robust system designs in discrete-event simulation, where robust system designs are system designs that are insensitive to uncontrollable system noise. A conceptual framework for automating the proposed experimental design strategy is constructed and a prototype system for testing the efficacy of the proposed strategy is developed. Concentration is on the domain area of manufacturing systems. The experimental design strategy proposed in this dissertation can be broken down into three phases. The first phase involves finding a range of feasible values for the system of design variables. This is accomplished by augmenting the simulation program with an expert system. The second phase involves constructing experimental design plans. The experimental design plans suggested are plans that allow robust system designs to be found. The third phase, the optimization phase, involves searching for a best system design, where a best system design is a system design which optimizes the performance measures of interest and is not sensitive to uncontrollable system noise. The strategy proposed is evaluated with two models of a jobshop.

In this work, we have investigated numerical techniques to determine the breakdown behavior of complex semiconductor devices using two-dimensional simulation. In particular, we have augmented the device simulator SEPSIP with a capability for handling single and multiple floating field rings, and for handling devices with slanted edges. We have furthermore improved the grid width selection algorithm in SEPSIP. A capability for plotting equi-field contours was added to the code. Finally, all system dependencies were removed from the SEPSIP code, and a new version of SEPSIP (Version 2.0) was generated which can be executed on any PC/XT, PC/AT, or PC/386 compatible computer. This eliminates the need for transfering files back and forth between the PC, which had formerly been used as an I/O processor, and the VAX, which was used for numerically intensive computations. It also makes the code more accessible to scientists and engineers who are working in this important research area.

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