سال:1392 | دوره: | شماره: |تعداد مقالات:8

This paper presents a discrete-time single-server finite buffer N threshold policy queue with renewal input and discrete Markovian service process. The server terminates service whenever the system becomes empty, and recommences service as soon as the number of waiting customers in the queue is N. We obtain the system-length distributions at prearrival and arbitrary epochs using the supplementary variable and the imbedded Markov chain techniques. Various performance measures such as the loss probability, mean queue length and mean waiting time in the queue along with some numerical results have been presented. The proposed model has potential applications in the areas of computer and telecommunication systems.

The object of this paper is to derive certain sufficient conditions for close-to- convexity of certain analytic functions defined on the unit disk ∆:={z ∈C: |z|<1}.

We consider a mathematical model of epidemic spread in which the population is partitioned into five compartments of susceptible S (t), Infected I (t), Removed R (t), Pre- vented U (t) and the Controlled W (t). We assume each of the compartments comprises of cohorts of individuals which are identical with respect to the disease status. We derive five systems of equations to represent each of the subpopulations. The general stability of the disease free equilibrium (DFE) and the endemic equilibrium states of the linearized model are established using the linear stability theory and the Routh-Hurwitz conditions are established and analyzed in the domain of interest. We find that the DFE is locally asymptotically stable when the infected individuals received ART and use the condom but the endemic state is unstable to initial perturbations. Also, we derive an expression for the basic reproduction number using the next generation matrix approach and find that for R0<1 the DFE is stable but for R0>1 is unstable.

Clustering of objects is an important area of research and application in variety of fields. In this paper we present a good technique for data clustering and application of this technique for data clustering in a closed area. We compared this method with K-nearest neighbor and K-means.

The purpose of this study is to demonstrate the potential of Imperialist Competitive Algorithm (ICA) for solving Blasius differential equation. This algorithm is inspired by competition mechanism among Imperialists and colonies and has demonstrated excel- lent capabilities such as simplicity, accuracy, faster convergence and better global optimum achievement in contrast to other evolutionary algorithms. To validate the proposed approach, the results of ICA were finally compared with exact solution of variational iteration method (VIM). Based on the results, current method can be easily extended to solve a wide range of problems.

To help improve customer relationship management (CRM), greater emphasis is given to the aspect of quality in the supply chain management and improve supply chain performance through is integrated business management and strategic partnerships. On the other hand, strategic supply chain management decisions are made at a company level that determine benefits and efficiencies of the supply chain and effective management of supply chains assists to product and delivery of a variety of products at low cost, high quality products, short lead times and services at the least cost. Hence, performance evaluation is of most importance for effective supply chain management. This paper gives a new application of DEA model, and FDH model to evaluate the supply chain. The basic motivation is to ensure that efficiency evaluations are effected from only observed performances.

In this paper, Elzaki Homotopy Perturbation Method is employed for solving linear and nonlinear differential equations with a variable coefficient. This method is a combination of Elzaki transform and Homotopy Perturbation Method. The aim of using Elzaki transform is to overcome the deficiencies that mainly caused by unsatisfied conditions in some semi- analytical methods such as Homotopy Perturbation Method, Variational Iteration Method and Adomian Decomposition Method. The approximate solutions obtained by means of Elzaki Homotopy Perturbation Method were compared in a wide range of problem’s domain with those results obtained by Homotopy Perturbation Method. The comparison shows a precise agreement between the exact solutions and the obtained results by this new method as an applicable one, which needs less computation and is much easier and more convenient than others. So, it can be widely used in engineering and other branches of science.

Abstract. Recently, some authors proposed the use of symmetric weights for computing the elements of cross-efficiency matrix. In spite of the fact that the proposed method decreases the number of zero weights, a large number of zero weights may still exist among input and output symmetric weights. To decrease the number of input and output symmetric weights, this paper improves the proposed secondary goal model. The improved method generates more acceptable results in the ranking process of the Decision Making Units (DMUs). Finally, a numerical example is provided to illustrate the applicability of the proposed method.