cellular manufacturing system (cms) is highly important in modern manufacturing methods. given the ever increasing market competition in terms of time and cost of manufacturing, we need models to decrease the cost and time of manufacturing. in this study, cms is considered in condition of dynamic demand in each period. the model is developed for facing dynamic demand that increases the cost of ...

In this paper‎, ‎using the discrete Fourier transform in the finite-dimensional Hilbert space C^n‎, ‎a class of nonRieszable equal norm tight frames is introduced ‎and‎ using this class, a bound for Fiechtinger Conjecture is presented. By the Fiechtinger Conjecture that has been proved recently, for given A,C>0 there exists a universal constant delta>0 independent of $n$ such that every C-equal...

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...

this paper presents a new nonlinear mathematical model to solve a cell formation problem which assumes that processing time and inter-arrival time of parts are random variables. in this research, cells are defined as a queue system which will be optimized via queuing theory. in this queue system, each machine is assumed as a server and each part as a customer. the grouping of machines and parts...

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...

In this study, we introduce a new two-way relay channel and obtain an inner bound and an outer bound for the discrete and memoryless multiple access relay channels with receiver-source feedback via two-way relay channel in which end nodes exchange signals by a relay node. And we extend these results to the Gaussian case. By numerical computing, we show that our inner bound is the same with o...

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...