Matching strengths of answers in fuzzy relational databases

Imprecise information is represented by fuzzy disjunctive information, and an extended fuzzy relational model is used to accommodate such information. In the presence of imprecise information, answers to a query can be categorized into two kinds of answers: sure answers and possible answers. To find more likely answers to a given query, the authors develop a method to measure the matching strength of each tuple as an answer to the query. The quality of an answer is higher in the case where less extra information is required and the more sure information is provided     

Cavitation behavior in superplastic 5083 Al alloy during multiaxial gas blow forming with lubrication

Despite its importance for industrial applications, the effect of lubrication on the cavitation behavior of superplastic materials has been given little attention. In this paper, a series of experiments were performed regarding bulging superplastic 5083 Al alloy sheet into dies with a cylindrical (cup) and rectangular (pan) die cavity for forming with and without lubrication, the formed parts were then evaluated to determine the effect of lubrication on the cavitation level evolution, thickness distribution, and void distribution. It was found that void shrinkage took place in the overlaid region for both forming with and without lubrication. The maximum void volume fraction could be effectively reduced for forming with lubrication; however, reductions in the maximum void volume fractions for cup forming were less significant than those for pan forming.     

Cavitation characteristics of a superplastic 5083 Al alloy during gas blow forming

Cavitation behavior of a superplastic 5083 Al alloy during gas blow forming has been investigated by deforming the sheet into a die with a rectangular cavity. Cavitation characteristics could be separated into two stages. In stage I, the sheet deformed freely as part of a hemi-cylindrical shape, cavity volume increased exponentially with deformation. The evolution of cavity volume was due to both nucleation and growth of cavities. In the second stage the surface friction would restrict thinning of the sheet, and the cavity volume first increased and then decreased with forming time for all test-forming rates. Decrease in cavity volume in the later stage could be related to the cavity shrinkage rising from sintering effect. A higher strain rate utilizing a higher imposed pressure during blow forming led to a greater average cavity shrinkage rate.