Microbiological quality of packaged bottled water and public water supply in Ibadan, Nigeria

ME Coker, AO Ehimika
2006 Journal of Applied Science, Engineering and Technology  
This paper presents an overview of knowledge-based system (KBS) in the context of decision making methodologies used in materials selection for the design of light weight aircraft metallic structures. Overall aircraft weight reduction means substantially less fuel consumption and better efficiency. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures in the aircraft. Two distinct multiple criteria decision making (MCDM) methodologies are
more » ... logies are presented with examples featuring a set of short-listed materials suitable in the design of the structures. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes satisfying the design requirements. Presently, aluminum alloys with high strength-toweight ratio have been second-to-none in most of the lightweight aircraft parts manufacturing. Magnesium alloys that are much lighter in weight and have impressive strength-to-weight ratios as alternatives to the use of aluminum alloys in the structures are examined using the methodologies. Ashby's approach of materials selection is generalized and materials are ranked based on the individual material index values. Finally, Materials are ranked based on the results obtained using the methodologies and are compared with those obtained using generalized Ashby's approach of materials selection. Any disparity among the individual materials ranking results are discussed. ABSTRACT This paper presents an overview of knowledge-based system (KBS) in the context of decision making methodologies used in materials selection for the design of light weight aircraft metallic structures. Overall aircraft weight reduction means substantially less fuel consumption and better efficiency. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures in the aircraft. Two distinct multiple criteria decision making (MCDM) methodologies are presented with examples featuring a set of short-listed materials suitable in the design of the structures. Pre-defined constraint values, mainly mechanical properties, are employed as relevant attributes satisfying the design requirements. Presently, aluminum alloys with high strength-to-weight ratio have been secondto-none in most of the lightweight aircraft parts manufacturing. Magnesium alloys that are much lighter in weight and have impressive strength-to-weight ratios as alternatives to the use of aluminum alloys in the structures are examined using the methodologies. Ashby's approach of materials selection is generalized and materials are ranked based on the individual material index values. Finally, Materials are ranked based on the results obtained using the methodologies and are compared with those obtained using generalized Ashby's approach of materials selection. Any disparity among the individual materials ranking results are discussed.
doi:10.4314/jaset.v5i1.38290 fatcat:cxczsanwp5fsrmxu5lh5rmphxi