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Applications of fuzzy theories to multi-objective system optimizationMost of the computer aided design techniques developed so far deal with the optimization of a single objective function over the feasible design space. However, there often exist several engineering design problems which require a simultaneous consideration of several objective functions. This work presents several techniques of multiobjective optimization. In addition, a new formulation, based on fuzzy theories, is also introduced for the solution of multiobjective system optimization problems. The fuzzy formulation is useful in dealing with systems which are described imprecisely using fuzzy terms such as, 'sufficiently large', 'very strong', or 'satisfactory'. The proposed theory translates the imprecise linguistic statements and multiple objectives into equivalent crisp mathematical statements using fuzzy logic. The effectiveness of all the methodologies and theories presented is illustrated by formulating and solving two different engineering design problems. The first one involves the flight trajectory optimization and the main rotor design of helicopters. The second one is concerned with the integrated kinematic-dynamic synthesis of planar mechanisms. The use and effectiveness of nonlinear membership functions in fuzzy formulation is also demonstrated. The numerical results indicate that the fuzzy formulation could yield results which are qualitatively different from those provided by the crisp formulation. It is felt that the fuzzy formulation will handle real life design problems on a more rational basis.
Document ID
19910006699
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Rao, S. S. (Purdue Univ. West Lafayette, IN, United States)
Dhingra, A. K. (Purdue Univ. West Lafayette, IN, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1991
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
NASA-CR-177573
NAS 1.26:177573
A-91029
Accession Number
91N16012
Funding Number(s)
CONTRACT_GRANT: NCA2-223
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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