We study the stochastic machine replenishment problem, which is a canonical special case of closed multiclass queuing systems in Markov decision theory. The problem models the scheduling of processor repairs in a multiprocessor system in which one repair can be made at a time and the goal is to maximize system utilization. We analyze the performance of a natural greedy index policy for this pro...

Multi-class closed queuing networks with synchronization stations find applications in analytical models of assembly systems and production systems operating under pull control policies. These queuing networks are hard to analyze exactly and therefore approximation methods must be used for performance evaluation. In this research we propose a new efficient approach based on parametric decomposi...

In this paper we study the relations between multiclass BCMP-like service stations and generalized stochastic Petri nets (GSPN). Representing queuing discipline with GSPN models is not easy. We focus on representing multi-class queuing systems with different queuing disciplines by defining appropriate finite GSPN models. Note that queuing discipline in general affects performance measures in mu...

the hierarchical hub location problem is encountered three-level network that is applied in production-distribution system, education system, emergency medical services, telecommunication network, etc. this paper addresses the hierarchical hub covering problem with single assignment accounting for mandatory dispersion of central hubs restriction as a special case. this formulation with incorpor...

This paper presents a new multi-objective mathematical model for the hub location and routing problem under uncertainty in flows, costs, times, number of job opportunities. aims at minimizing total transportation cost consisting fixed maximizing employment regional development as social responsibility. An M/M/c/K queue system is applied to estimate waiting time nodes maximize responsiveness. Al...

The hub median problem is to locate hub facilities in a network and to allocate non-hub nodes to hub nodes such that the total transportation cost is minimized. In the hub center problem, the main objective is one of minimizing the maximum distance/cost between origin destination pairs. In this paper, we study uncapacitated hub center problems with either single or multiple allocation. Both pro...

In this paper we consider a capacitated single allocation p-hub median problem with multiple capacity levels (CSApHMPMC) in which the decisions are to determine the location of p hubs and their capacity levels, the single allocation of non-hub nodes to hubs in the logistics network. This problem is formulated as an integer programming model with the objective of minimizing the sum of total tran...

Regarding the fact that getting a suitable combination of the human resources and service stations is one of the important issues in the most service and manufacturing environments, In this paper, we have studied the two models of planning queuing systems and its effect on the cost of the each system by using two fuzzy queuing models of M/M/1 and M/E2/1. In the first section, we have compar...

In this article, modeling in queuing systems with heavy traffic customer flows is reviewed. Key areas include their limiting distributions, asymptotic behaviors, modeling issues and applications. Heavy traffic flows are features of queuing in modern communications, transportation and computer systems today. Initially, we reviewed the onset of asymptotic modeling for heavy traffic single server ...