Search

This paper presents the motivation for the construction of a digital computer simulation of the American military's strategic airlift system, the author's analysis of that system preparatory to the simulation design, and the currently anticipated application of the model to studies of strategic mobility. Emphasis is placed on the estimation of the airlift productivity function for its subsequent utilization in appropriate strategic mobility models employed by the Joint Chiefs of Staff and by the Office of the Assistant Secretary of Defense (Systems Analysis). Those variables suspected of being primary contributors to gains in marginal airlift productivity are delineated in a description of the modules constituting the model. Finally, a sketch of an hypothetical experimental design, permitting the systems analyst to specify sequentially model iterations so as to obtain valid statistical estimates of desired marginal productivities, serves as a conclusion to the paper. [ABSTRACT FROM AUTHOR]

When computer simulation is being used to investigate a problem, any attempt at obtaining an optimum solution usually involves a search of the relevant factor space. Became a number of search techniques are available, it is desirable to bye some criteria for selecting the technique to be used in a specific simulation situation. However, no mathematical basis exists for an evaluation of these techniques relative to characteristics, that may vary from simulation to simulation. Thus, it is necessary to perform empirical studies ia order to obtain the required information. This paper discusses the homework and results of an empirical evaluation of the performance of name search techniques. It wag based on applying the techniques to various multidimensional situations that were constructed so that the true optimum vas known, providing comparison of the performance of each technique with the true optimum, as well as with the performance of other techniques. Each of the search techniques was evaluated for a variety of simulation characteristics in the situation where the available number of computer runs was relatively small compared with the number of factors being examined. [ABSTRACT FROM AUTHOR]

This paper is concerned with the manner in which an investigation by simulated experimentation is conducted, after the model has been formulated and the computer program completed. It considers the problem of estimating the precision of the results obtained, and methods of improving the precision of results. Alternative procedures are discussed and recommendations are given. [ABSTRACT FROM AUTHOR]

This paper presents the results of some digital computer simulation tests of a procedure for the economic planning of lot sizes, work force, and inventories. A dynamic, deterministic, linear programming model was used to obtain approximate solutions to the actual problem which is both dynamic and stochastic. The tests were made with data taken from an actual factory. An alternate procedure, based upon single-item inventory control, was also tested; its results were compared with those obtained from the linear programming model. On the basis of these tests, this linear programming method appears to offer a promising method for the practical economic planning of production activities. [ABSTRACT FROM AUTHOR]

Of interest to the Operations Research Office for several years has been the problem of improving the efficiency of Army communications systems Involved in these studies, besides obvious problems of communications equipments, are problems of organization and human handling operations To understand and offer solutions to these latter problems, electromechanical simulation equipment has been developed that displays the network of handling operations and provides estimates of congestion at any or all points in the system In the analog each node consists of a display and register unit upon which columns of lights represent items in a waiting line Distributions of arrival times of input items and servicing times are programmed on standard teletype tape fed to the analog by teletype transmitters The register unit at each point of the network displays the queue, computer state occupancy times, and provides estimates of state probabilities Continuous records of the system states are maintained by pen recorders so that individual delay times and empirical estimates of their distributions mas he obtained The register units may be connected in parallel or tandem, representing various sequential or parallel operations Available as important queue disciplines are the handling of multiple inputs on a priority basis and the automatic adjustment of servicing rates according to transient loads [ABSTRACT FROM AUTHOR]