Joseph M. Mellichamp

Software development cost estimation using function points

This paper presents an assessment of several published statistical regression models that relate software development effort to software size measured in function points. The principal concern with published models has to do with the number of observations upon which the models were based and inattention to the assumptions inherent in regression analysis. The research describes appropriate statistical procedures in the context of a case study based on function point data for 104 software development projects and discusses limitations of the resulting model in estimating development effort. The paper also focuses on a problem with the current method for measuring function points that constrains the effective use of function points in regression models and suggests a modification to the approach that should enhance the accuracy of prediction models based on function points in the future. >

A statistical expert system for simulation analysis

Efforts on a number of fronts are being made to enhance the usefulness of simulation as a tool for analysis. Graphical input, animation, automated program generation, model management utilities, and user interactive environments all address the issue of ease of use. Even with the current emphasis in this regard, simulation suffers from several shortcomings which preclude even greater application of the methodology. One of the more signifi cant limitations is the dependence of simulation on statistical methodologies. Practically every phase of simulation analysis in volves one or more statistical issues. And the fact of the matter is that many simulation practitioners have neither the statistical skills nor the access to qualified statisticians to effectively address these crucial issues. The obvious solution to this problem would be to have an ex pert statistician available during every simulation study to answer any questions concerning statistical issues. A more practical alter native is to make available an expert system which could func tion as a statistical advisor to simulation analysts. This option seems ideally suited for expert system techniques since it is well- defined and narrowly bounded and an appropriate body of statistical knowledge exists. The objective of this research was to develop such an expert statistical consultant. The system would be able to advise as well as perform appropriate computations for a variety of statistical issues including input data analysis, design of experiments, and output analysis. An overview of the proposed system is given and illustrations of the capabilities of the system are presented.

FMS Designer: An expert system for flexible manufacturing system design

SUMMARY Implementation of flexible manufacturing technology in the batch manufacturing environment has created major problems for designers and engineers who are responsible for specification and design of flexible manufacturing systems (FMS). The FMS design task appears to be an excellent application for expert systems techniques. This paper describes current results of an ongoing research effort to develop an expert system which analyses the output from an FMS simulation model, determines whether operational and financial objectives are met, identifies design deficiencies or opportunities for improvement, and proposes designs which overcome deficiencies or exploit improvement opportunities. An overview of the FMS design expert system is given and a case study is presented to illustrate how the system operates. Areas for future research are also discussed.

Process planning simulation: an FMS modeling tool for engineering

Simulation methods are effectively used to investigate design issues of a proposed flexible manufacturing system (FMS). Un fortunately, process design engineers rarely have the necessary expertise to take full advantage of simulation methodology. Pro cess Planning Simulation (PPS) is a software package which allows engineers with virtually no simulation expertise to define FMS designs and generate the simulation code necessary to model designs of interest. PPS uses SIMAN to model process elements of an FMS, and IFPS to model the financial aspects of the system.

Automating design for manufacturability through expert systems approaches

In the light of growing global competition, organizations around the world today are constantly under pressure to produce high-quality products at an economical price. The need to manufacture products that perform efficiently in a cost effective manner is essential for the profitability and survival of organizations. Consequently, organizations have become increasingly aware of the importance of product design and are striving to improve manufacturing processes in order to introduce products to the market with the least development time.

An interactive debugging expert system for GPSS/H simulation models

Many enhancements to simulation methodol ogy which will reduce the burden on the simulation analyst are likely to come as a result of the integration of expert systems methodol ogy with simulation. One phase of the simulation approach which appears to have particular promise for the integration of expert systems methodology is the model development task. This is perhaps the most time consuming step in the simulation approach and probably requires the highest level of expertise. Interest ingly, the piece of the model development task which is almost certainly the most frustrating to the analyst — program debugging — has attracted very little attention from an expert system perspective. Thus, it would appear that there is both a need and an opportunity for expert systems that could assist system analysts in the program debugging task. The major objective of this research was to develop an expert system which could function as a debugging advisor to simulation analysts. A second objective was to evaluate the expert system and from the evaluation try to make generalizations about the most viable form and structure for such systems in order to guide future research efforts in this area.

An image enhanced, knowledge based expert system for maintenance trouble shooting

Abstract This paper describes the results of a successful effort to develop a vehicle trouble-shooting expert system which has imaging capability integrated into its knowledge base. The system is used to diagnose maintenance problems in the electrical/hydraulic subsystem of a D-900 Derrick. Video information required to effectively execute this diagnostic task is obtained through the use of a TARGA image capture board in a standard PC platform. This paper contains a discussion of the general use of imaging in this context along with a description of the expert system incorporating this capability. A summary of several design and implementation issues that emerged during the research is also included.

Analysis of Excess Stock in Multiproduct Inventory Systems

Abstract A primary function of production management is the control of inventories. The typical manner of economic inventory control calls for a “pre-stocking” approach in which the focus is on the reorder quantities which should be put into inventory. A second manner of controlling inventories is what can be called a “post-stocking” analysis. Here the focus is on how much of the present inventory already in stock should be declared as surplus and disposed of. This paper describes the development and implementation of an analytical procedure for this second, excess inventory issue. The procedure is described in the context of an application to a General Motors carburetor assembly process in which product structure interactions play a significant role.

Development of design guidelines for local area CSMA/CD networks

A local area communications network is complex with many interdependent variables which influence system perfor mance. The purpose of this research was to develop simplified design guidelines that can be used by local area communications network designers. These guidelines apply to situations where designers are consider ing the CSMA/CD contention access protocol. A simulation model applied to this type environment can aid in design by helping to define the range of efficient system operation during the preliminary network configuration design and evalua tion. The research includes the development of a GPSS simulation model that is used to analyze the effects of network design variables. These variables are considered in an experimental design that inputs simula tion results to a multiple regression analysis. The resulting regression equation offers network designers a simplified tool useful in estimating message transmission delay. This will provide an easy method for network perfonnance evaluatiort during the initial network design phase when sophisti cated simulation or analytical modeling techniques are not applicable or not appro priate to the design environment.

Computer Aided Machine Qualification

This article concerns the process of conducting a machine qualification (or process capability) study. It presents the results of a research project undertaken to investigate the shortcomings inherent in the typical team approach to machine qualification, and to design a comprehensive computer system to overcome these shortcomings. The article begins with a discussion of the steps involved in a qualification study, pointing out that inefficiencies and inaccuracies often arise due to the heavy time and statistical burden placed on the study team. The functionality and the features of the PC‐based computer system developed in the research are described. Numerous screens are provided to illustrate these features. Finally, a synopsis is given of the primary benefits of the system, as well as its limitations.