This paper presents a fuzzy Choquet integral approach which is used to evaluate the capability of supplier and then to deal with the supplier selection problem. Firstly, the basic of fuzzy measures and Choquet integral are introduced. Secondly, linguistic terms expressed in trapezoidal fuzzy numbers are used to assess the ratings for the suppliers' quality and the importance of criteria. Then, an evaluation model based on the fuzzy measure and Choquet integral theory is proposed, and we give the detailed procedure with an example. This paper shows that the proposed model is very well suited as an evaluation tool for supplier selection decisions.
As product structure becomes more and more complex, the fault mode presents a diversified trend, and it is more difficult to determine the causes of system failure for a complex product. The main objective of this study is to provide an effective failure analysis method based on the combination of fault trees analysis (FTA) and generalized grey relation analysis (GGRA) for complex product. In this method, the product system failure is defined and the fault tree is constructed by FTA methodology firstly; and then GGRA is employed to identify the correlations between each fault mode and the system failure; finally, the main causes of system failure are identified and the corresponding measures can be made. A case study of a WD615 Steyr engine is conducted throughout the text to verify the validity of this method. The present study would help facilitate the failure and reliability analysis for complex product and benefit designers for the product improvement.
The gas turbine blade was studied on the condition that the mainstream velocity was 10m/s and the Renolds number based on the chord length of the blade was 160000.The Hot-film anemometer was used to measure the two-dimension speed distribution along the downstream of the film cooling holes on the suction side and the pressure side. The conclusions are as follows: When the blowing ratio of the suction side and the pressure side increasing, the the mainstream and the jet injection mixing center raising. Entrainment flow occurs at the position where the blade surface with great curvature gradient, simultaneously the mixing flow has a wicked adhere to the wall. The velocity gradient of the u direction that on the suction side increase obviously, also the level of the wall adherence is better than the pressure side. With the x/d increasing, the velocity u that on the pressure side gradually become irregularly, also the secondary flow emerged near the wall region where the curvature is great. The blowing ratio on the suction side has a little influence on velocity v than that on the pressure side.
On the analysis of the disadvantage of traditional Failure Mode and Effect Analysis (FMEA), an improved FMEA based on fuzzy set theory and Analytical Hierarchy Process (AHP) is proposed. In this method, the fuzzy language set and the fuzzy number of Severity (S), Occurrence (O) and Detection (D) are firstly set up, then failure modes are evaluated, and finally the weights of S, O and D are determined by AHP. So, risk priorities of the failure modes can be determined by calculating the modified Risk Priority Number (RPN). Improved FMEA could provide a method for the company to evaluate the reliability analysis of products.
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