Microstructure and Mechanical Properties of a Dissimilar Friction Stir Weld between Austenitic Stainless Steel and Low Carbon Steel

Dissimilar fusion welding of austenitic stainless steels to carbon steels has some metallurgical and technical problems.It was suggested that the solid-state nature of friction stir welding(FSW) can overcome these problems and produce a sound weld with reliable mechanical properties.In this study,plates of 304 stainless steel and st37 steel were welded together by FSW at tool rotational speed of 600 r/min and welding speed of 50 mm/min.In the stir zone(SZ) of 304 stainless steel,the results showed a refined grain structure with some features of metadynamic recrystallization.In the SZ of st37 steel,the hot deformation of material in the austenite region produced small austenite grains.These grains transformed to fine ferrite and pearlite by cooling the material after FSW.The production of fine grains increased the hardness and tensile strength in the SZ of both sides with respect to their base metals(BMs).     

A Fuzzy Variable Least Core Game for Inter-basin Water Resources Allocation Under Uncertainty

In this paper, a new solution concept, called Fuzzy Variable Least Core (FVLC), is developed for fuzzy cooperative games. The FVLC is able to incorporate fuzzy input variables and result in fuzzy benefit shares of players participating in a coalition. This solution concept is used for water and benefit allocation to water users in inter-basin water transfer systems considering the uncertainties associated with their benefit coefficients. In the proposed water allocation methodology, an Integrated Stochastic Dynamic Programming (ISDP) model is developed to obtain the water rights of players and economic water allocation policies. In the next step, the total net fuzzy benefit of the system is reallocated to water users in an equitable and rational way using a FVLC-based model. In this model, a new algorithm is proposed for converting a multilateral cooperative game with fuzzy variables to some fuzzy bilateral cooperative games, which are solved using the FLVC solution concept. The applicability and efficiency of the proposed methodology is examined by applying it to a large scale inter-basin water transfer project in Iran.