some incidents in urban railway systems affect the function of the subway’s company adversely and they could disorder the services. these events may inflict irreparable damage to passengers, employees and equipment. by recognizing the hazards existing in this type of transportation system and evaluating and prioritizing risks, we can perform appropriate actions to reduce the probability and sev...

In ordinary transportation problems, it is always supposed that the mileage from every source to every destination is a definite number. But in special conditions, such as transporting emergency materials when natural calamity occurs or transporting military supplies during wartime, carrying network may be destroyed, mileage from some sources to some destinations are no longer definite. It is u...

this study focused on the optimization of al—mg to cuzn34 friction stir lap welding (fslw) process for optimal combination of rotational and traverse speeds in order to yield favorable fracture load using grey relational analysis (gra). first, the degree of freedom was calculated for the system. then, the experiments based on the target values and number of considered levels, corresponding orth...

This study focused on the optimization of Al—Mg to CuZn34 friction stir lap welding (FSLW) process for optimal combination of rotational and traverse speeds in order to yield favorable fracture load using Grey relational analysis (GRA). First, the degree of freedom was calculated for the system. Then, the experiments based on the target values and number of considered levels, corresponding orth...

Purpose – The purpose of this paper is to advance new rules about operations of grey numbers. Design/methodology/approach – The paper first puts forward the definitions of basic element of grey number and general grey number. The operation axiom, operation rules of general grey numbers and a new algebraic system for general grey numbers are built based on the “kernel” and the degree of greyness...