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The field of medical informatics comprises many subdisciplines, united by a common interest in the establishment of standards to facilitate the sharing, reuse, and understanding of information. This work depends in large part on the ability of controlled medical terminologies to represent relevant concepts. This work augments a controlled terminology to provide not only standardized content, but also standardized explanatory knowledge for use in expert systems. This experiment consisted of four phases centered on the use of the controlled terminology-- Systemized Nomenclature of Medicine (SNOMED). The first phase evaluated SNOMED's ability to express explanatory knowledge for clinical pathology. The second developed the Normalized Medical Explanation (NORMEX) syntax for expressing and storing pathways of causal reasoning in the domain of clinical pathology. The third segment examined SNOMED's capacity to represent concepts used in the NORMEX model of clinical pathology. The final phase incorporated NORMEX-based pathways of influence in a Bayesian network to assess ability to predict causal mechanisms as implied by serum analyte results. Findings from this work suggest that SNOMED's capacity to represent explanatory information parallels its coverage of clinical pathology findings. However, SNOMED currently lacks much of the content necessary for both of these purposes. Additional explanatory content was created with an ontology-modeling tool. The NORMEX syntax was defined by SNOMED hierarchy names. Complex sequences of explanations were created using the NORMEX syntax. In addition, medical explanatory knowledge represented in the NORMEX format could be stored in an architectural framework consistent with that used by a controlled terminology such as SNOMED. Once stored, such knowledge could be retrieved from storage without loss of meaning or introduction of errors. Lastly, a Bayesian network constructed from the retrieved NORMEX knowledge produced a network whose prediction performance equaled or exceeded that of a network produced by more traditional means. / Ph. D.

Simulation optimization is a developing research area whereby a set of input conditions is sought that produce a desirable output (or outputs) to a simulation model. Although many approaches to simulation optimization have been developed, the research area is by no means mature. This research makes three contributions in the area of simulation optimization. The first is fundamental in that it examines simulation outputs, called "response surfaces," and notes their behavior. In particular both point and region estimates are studied for different response surfaces: Conclusions are developed that indicate when and where simulation-optimization techniques such as Response Surface Methodology should be applied. The second contribution provides assistance in selecting a region to begin a simulation-optimization search. The new method is based upon the artificial intelligence based approach best-first search. Two examples of the method are given. The final contribution of this research expands upon the ideas by Crouch for building a "Learner" to improve heuristics in simulation over time. The particular case of parameter-modification learning is developed and illustrated by example. The dissertation concludes with limitations and suggestions for future work. / Ph. D.

A derivation of the Michaelis-Menton growth kinetics model is developed to simulate batch fermentation of glucose to ethanol using yeast. / Master of Science

The software tool described in this thesis demonstrates a practical application of prototype theory to the representation of world or encyclopedic knowledge. The tool is designed to extract such knowledge from dictionary entries and to represent it in a network of frames. An application needing encyclopedic knowledge would rely on some separate utility program to draw information from the frames, translating frame data as necessary for s own use. The encyclopedic knowledge that can be extracted from a dictionary extends over an extremely wide range of topics, but it is very shallow, so the knowledge base of any final application would require further enrichment from other sources. However, a substantial part of the deficit might be overcome through similar automatic processing of more dictionaries and other published sources of encyclopedic knowledge. / Master of Science

The design of reinforced concrete beams involves the selection of design parameters such as beam dimensions and reinforcement details which result in a safe and economical section. This process of design consists of three stages: preliminary design, structural analysis, and detailed design which includes the selection of dimensions, reinforcement, and stirrups. The design process is an iterative one where considerable judgement and experience are required. This is an ideal situation for the application of expert system technology. A knowledge based expert system called BEAMDES was developed for the flexure design of reinforced concrete beams in accordance with ACI 318-83 specifications. The expert system was developed using the micro-computer based expert system shell, Insight 2+. BEAMDES can be used to design both rectangular and tee sections. The beams can be simply supported, cantilevered, or continuous. The results obtained from BEAMDES were tested against several example problems for both supported and continuous beams. It was found that the designs recommended by the system were similar to those of the examples. / Master of Science

The selection and sizing of the components for the design of a hydrostatic transmission is a tedious process. Necessary procedures include: analyzing the load profile, choosing a suitable configuration, determining the required size of components, selecting components, evaluating the performance of selected units, and then adjusting or selecting alternate components for improved performance. A. rule-based expert system, called HSTX, was developed to aid the selection and sizing of the major components-- pump, motor, and final drive-- of a hydrostatic transmission. Four types of options were considered. For the first, output speed and torque are both constant. For the second, horsepower output is constant at different speeds. For the third type, the output torque is constant at different speeds. For the last, torque and horsepower outputs can vary over a wide range of speeds. The program selects one of the four combinations of fixed pump and fixed motor, fixed pump and variable motor, variable pump and fixed motor, or variable pump and variable motor to match the desired outputs. The HSTX program includes databases which contain the specifications of hydraulic pumps and motors from selected manufacturers. HSTX interactively prompts the user to enter basic problem constraints and performance requirements. The program then recommends system configuration and selects components from the databases to meet the performance requirements specified. To assist inexperienced designers, HSTX is designed in such a way that the program gives easily understood hints, explanations, and guidance. The program, HSTX, can analyze the load profile, size the components, select available components from a database, evaluate the performance, and output the final results. Trial runs with different operators indicate that HSTX can be effectively used by a designer with a background in hydraulic systems but with little background in HST design. / Master of Science

Testing programs with tractable algorithms is one area in which software engineers have made numerous advances over the past few decades. Testing rule-based expert systems, however, is a new area in software engineering which requires new testing techniques. For the most part, traditional software engineering testing strategies assume modular program development. This assumption is impractical to make for expert system development, for the knowledge base of an expert system is quite simply a huge non-modular program. It consists almost entirely of non-ordered, multi-branching decision statements. In traditional programming, the module interfaces are limited and well defined. For rule-based expert systems, the interaction among rules is combinatoric and highly data-driven. Thus, the testing of a completed expert system via traditional path analysis is impractical. The design of a testing strategy for expert systems focuses on the generic phases of expert system development. Briefly, these phases include system definition, incremental system implementation, and system maintenance.. Using this simplified breakdown of the expert system development process as a guide, certain testing techniques can be generalized enough to work for any expert system application. / Master of Science

Knowledge based systems are currently the most marketable products of Artificial Intelligence research. The process of developing a knowledge based system can be very time consuming and costly. This thesis provides an automated, structured, knowledge acquisition methodology for accelerated development of knowledge based systems. This constrained approach leads to considerable savings in development costs, and results in a modular system that is easy to maintain. The system acts as a design consultant' to help the expert in elucidating his knowledge to the end-users. / Master of Science

This research investigated the development of a prototype expert system to allocate manpower in service systems. The three expert system components - a global data base, a knowledge base, and a inference procedure - were built for application in different service facilities. The general service system constraint set was used in conjunction with an expert's allocation logic to specify the production rules within the prototype expert system's knowledge base. The sequencing of these production rules is controlled by the inference procedure. The protoype system can be applied in those service facilities that maintain similar service system constraints as the facility used in this research. A specific facility was used to demonstrate and analyze the prototype expert system. An allocation schedule generated by the expert system was compared to a manually generated schedule. Full-time manpower allocations were the same. Yet, part-time manpower allocations differed due to flexibility, availability and shift constraints. The user must evaluate the expert system's schedule and make reassignments where necessary. Thus, this research determined that an expert system can be utilized to allocate manpower in service facilities; however, further research is required to build an expert system that encompasses all service facilities. / M.S.