NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Uncertainty management by relaxation of conflicting constraints in production process schedulingMathematical-analytical methods as used in Operations Research approaches are often insufficient for scheduling problems. This is due to three reasons: the combinatorial complexity of the search space, conflicting objectives for production optimization, and the uncertainty in the production process. Knowledge-based techniques, especially approximate reasoning and constraint relaxation, are promising ways to overcome these problems. A case study from an industrial CIM environment, namely high-grade steel production, is presented to demonstrate how knowledge-based scheduling with the desired capabilities could work. By using fuzzy set theory, the applied knowledge representation technique covers the uncertainty inherent in the problem domain. Based on this knowledge representation, a classification of jobs according to their importance is defined which is then used for the straightforward generation of a schedule. A control strategy which comprises organizational, spatial, temporal, and chemical constraints is introduced. The strategy supports the dynamic relaxation of conflicting constraints in order to improve tentative schedules.
Document ID
19930009484
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Dorn, Juergen
(Wien Univ.)
Slany, Wolfgang
(Wien Univ.)
Stary, Christian
(Wien Univ.)
Date Acquired
September 6, 2013
Publication Date
May 1, 1992
Publication Information
Publication: NASA. Ames Research Center, Working Notes from the 1992 AAAI Spring Symposium on Practical Approaches to Scheduling and Planning
Subject Category
Cybernetics
Accession Number
93N18673
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available