Shanthikumar [10] studied the priority M/G/1 queue with server vacations and found that the difference between the waiting time distribution under the non-preemptive priority and that under the preemptive-resume priority is independent of the vacation policy. We extend this interesting property i) to the generalized vacations which includes the two vacation policies considered by Shanthikumar, ...

In this paper, we consider an M/M/1 queueing system with impatient customers and a variant of multiple vacation policy, where we examine the case that customer impatience is due to the servers’ vacation. Whenever a system becomes empty, the server takes a vacation. However, the server is allowed to take a maximum number of vacations, denoted by K vacations, if the system remains empty after the...

In the present paper, mathematical modeling for analyzing a Markovian queueing system with two heterogeneous servers and working vacation has been demonstrated. Keeping in view queueing situations in real life problems, here we consider service policy that initially both the heterogeneous servers take vacation when there are no customers waiting for service in the queue; however, after this ser...

DENSERKS is a Fortran sensitivity equation solver package designed for integrating models whose evolution can be described by ordinary differential equations (ODEs). A salient feature of DENSERKS is its support for both forward and adjoint sensitivity analyses, with built-in integrators for both first and second order continuous adjoint models. The software implements explicit Runge-Kutta metho...

This paper is concerned with the problem of production planning in a stochastic manufacturing system with serial machines that are subject to breakdown and repair. The machine capacities are modeled by a Markov chain. The objective is to choose the input rates at the various machines over time in order to meet the demand for the system’s production at the minimum long-run average cost of produc...

The condition equations are derived by the introduction of a system of equivalent differential equations, avoiding the usual formalism with trees and elementary differentials. Solutions to the condition equations are found by direct numerical optimization, during which simplifying assumptions upon the Runge-Kutta coefficients may or may not be used. Depending on the optimization criterion, diff...

In this paper, we treat an optimal control problem of a stochastic two-machine owshop with machines subject to random breakdown and repair. While the problem is diicult to solve, it can be approximated by a deterministic problem when the rates of machine failure and repair become large. Furthermore, beginning with the solution of the deterministic problem, we can construct a feedback control fo...

the management of machine replacement (specifically tractors) is one of the most critical factors for performing field operations on time. therefore, tractor repair and maintenance costs must be accurately predicted. this research was carried out to evaluate the use of the regression technique in predicting tractor repair and maintenance costs. the study was conducted using empirical data on 60...

The optimization of some W-methods [7] for the time integration of time-dependent PDEs in several spatial variables is considered. In [2, Theorem 1] several three-parametric families of three-stage W-methods for the integration of IVPs in ODEs were studied. Besides, the optimization of several specific methods for PDEs when the Approximate Matrix Factorization Splitting (AMF) [3, 4] is used to ...

Efficient resource management through the virtual machine placement (VMP) is a great concern in data centers. The Biobjective VPM is a representation of multi-objective combinatorial optimization problem. Energy or cost minimization of cloud data center is highly dependent upon the VMP policy. Allocating the set of virtual machines (VMs) to the set of suitable physical machines (PMs), while con...