All ETDs from UAB

Advisory Committee Chair

Kevin Reilly

Advisory Committee Members

James Buckley

Jeffrey Gray

Robert Hyatt

Randy Smith

Document Type


Date of Award


Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences


Simulations of modeled systems are e®ective tools for evaluating system attributes; fuzzy logic provides for simulation of systems with inherent uncertainties. This re- search to advance simulation of fuzzy systems involves several studies in a planned sequence. Continuous fuzzy system modeling activities constitute a ¯rst stage of re- search action, a natural °ow from earlier work on modeling discrete fuzzy systems; the notion of using crisp simulation to carry out fuzzy computations is at the heart of the work. This activity requires choosing tools and problems with which to demon- strate feasibility and broad applicability of the approach. Some fundamental issues underlying the work provoke new departures for the second stage consisting of two substages. The ¯rst substage involves a new fuzzy number (FN) concept, that of a B¶ezier generated FN (BGFN). These numbers were conceived at a very basic level to illustrate that the approach we take is not rooted in or con¯ned to simple tri- angular FNs (TFN) that are often used in modeling. Their potential lies in both previous discrete simulation and in continuous simulation. The second substage of continuous modeling pursues these numbers in relation to random FNs. The second stage includes these pursuits in parallel with investigations of sequences of random numbers (as they are required for fuzzy modeling). Sequences must be able to pass rigorous statistical inspection, for which we o®er some new ideas, at least in the fuzzy domain. A ¯nal phase of work, a third stage, from software cost estimation's (SCE) COnstructive COst MOdel (COCOMO), concerns f-COCOMO(fuzzy COCOMO). Our f-COCOMO studies may be viewed as software engineering (SE) re°ections on the entire modeling e®ort, but a broader tact is taken; that is, inherited from CO- ii COMO's broad perspective. Advances in fuzzy treatments of COCOMO open a new fuzzy modeling frontier relating to cost systems analysis. In our overview of the entire e®ort, we note the progression from discrete to continuous models, and address some theoretical and mathematical foundations as they arise. We also note that this pro- gression that culminates in fundamental SE contributions, parallels for fuzzy systems, a similar work°ow found in crisp systems.



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