in this paper, the direct extrusion process of bimetallic rods in conical dies is analyzed by an improved upper bound method. the deformation zone is subdivided into six smaller zones and by considering a non-spherical entrance boundary to the deformation zone, a velocity field is presented which is different from velocity fields employed in previous studies. the total power consumption of the ...

we consider online scheduling of jobs with specic release time on m identical machines. each job has a weight and a size; the goal is maximizing total weight of completed jobs. at release time of a job it must immediately be scheduled on a machine or it will be rejected. it is also allowed during execution of a job to preempt it; however, it will be lost and only weight of completed jobs contr...

in the present paper, the deformation zone of the ecae (equal channel angular extrusion) process was investigated using the upper bound theorem. for this purpose, the shape of the streamlines in the deformation zone was assumed to be cubic bezier curves. then, the force required for the ecae process was optimized with regard to the parameters defining the shape of streamlines by the upper bound...

precision forging process is widely used for the production of spur gears due to its advantages such asimproved strength and surface finish, little waste of materials and reduction in the machining time ofthe gear. an important aspect of precision forging process is the load required to perform the processsuccessfully and design the forging tools. in this research, a new kinematically admissibl...

rupture and wrinkling are two prevalent phenomena that happen in hydro-forming process. many efforts have been made to achieve the upper and lower bounds for the pressure related to rupture and wrinkling of sheet, respectively. the aim of this investigation is to improve the upper bound of fluid pressure in hydro-forming process by hemispherical punch. in this article, analytical study of the u...

‎In this paper we give an upper bound for Noetherian dimension of all injective modules with Krull dimension on arbitrary rings‎. ‎In particular‎, ‎we also give an upper bound for Noetherian dimension of all Artinian modules on Noetherian duo rings.

presented is a method of two-dimensional analysis of the active earth pressure due to simultaneous effect of both soil weight and surcharge of strip foundation. the study’s aim is to provide a rigorous solution to the problem in the framework of upper-bound theorem of limit analysis method in order to produce some design charts for calculating the lateral active earth pressure of backfill when ...

this paper considers the economic lot scheduling problem, that is, the problem of scheduling several products on a single facility so as to minimize holding and setup costs. combination of frequency and timing as well as production quantity make this problem np-hard. a heuristic is developed to obtain a good solution to elsp. the proposed heuristic makes use of the simulated annealing technique...