مجله بین المللی محاسبات و مدل سازی ریاضی
سال یکم شماره 1 (Winter 2011)

We developed an inventory model for decaying items with selling price dependent demand in inflationary environment. Deterioration rate is taken as two parameter Weibull distribution. Shortages in inventory are allowed with partial backlogging. Backlogging rate is taken as exponential decreasing function of time. Profit maximization technique is used in this study.

Orthogonal zero interpolants (OZI) are polynomials which interpolate the “zero-function” at a finite number of pre-assigned nodes and satisfy orthogonality condition. OZI’s can be constructed by the 3-term recurrence relation. These interpolants are found useful in the solution of constrained approximation problems and in the structure of Gauss-type quadrature rules. We present some theoretical and computational aspects of OZI’s and also discuss their structure and significance at the multiple nodes.

The selection of best Information System (IS) project from many competing proposals is a critical business activity which is very helpful to all organizations. While previous IS project selection methods are useful but have restricted application because they handle only cases with precise data. Indeed, these methods are based on precise data with less emphasis on imprecise data. This paper proposes a new integrated Data Envelopment Analysis (DEA) model which is able to identify most efficient IS project in presence of imprecise data. As an advantage, proposed model identifies most efficient IS project by solving only one Mixed Integer Linear Programming (MILP). Applicability of proposed method is indicated by using data set includes specifications of 8 competing projects in Iran Ministry of Commerce.

Data envelopment analysis (DEA) with considering the best condition for each decision making unit (DMU) assesses the relative efficiency for it and divides a homogenous group of DMUs in to two categories: efficient and inefficient, but traditional DEA models can not rank efficient DMUs. Although some models were introduced for ranking efficient DMUs, Franklin Lio & Hsuan peng (2008), proposed a common weights analysis (CWA) approach for ranking them. These DMUs are ranked according to the efficiency score weighted by the common set of weights and shadow prices. This study shows there are some cases that shadow prices of efficient DMUs are equal, hence this method is not applicable for ranking them. Next, we propose a new method for ranking units with equal shadow prices.

Quartic non-polynomial spline function approximation in off step points is developed, for the solution of fourth-order boundary value problems. Using consistency relation of such spline and suitable choice of parameter,we have obtained second, fourth and sixth orders methods. Convergence analysis of sixth order method has been given. The methods are illustrated by some examples, to verify the order of accuracy of the presented methods. The computed results are compared with other exiting methods, collocation, decomposition and spline methods. Computed result verify the applicability and accuracy of our presented methods.

In this paper, a Boussinesq equation is solved by using the Adomian's decomposition method, modified Adomian's decomposition method and homotopy analysis method. The approximate solution of this equation is calculated in the form of series which its components are computed by applying a recursive relation. The existence and uniqueness of the solution and the convergence of the proposed methods are proved in detail. A numerical example is studied to demonstrate the accuracy of the presented methods.

In this paper it is shown that the use of‎ ‎uniform meshes leads to optimal convergence rates provided that‎ ‎the analytical solutions of a particular class of‎ ‎Fredholm-Volterra integral equations (FVIEs) are smooth‎.

The collocation method based on cubic B-spline, is developed to approximate the solution of second kind nonlinear Fredholm integral equations. First of all, we collocate the solution by B-spline collocation method then the Newton-Cotes formula use to approximate the integrand. Convergence analysis has been investigated and proved that the quadrature rule is third order convergent. The presented method is tested with four examples, and the errors in the solution are compared with the existing methods [1, 2, 3, 4] to verify the accuracy and convergent nature of proposed methods. The RMS errors in the solutions are tabulated in table 3 which shows that our method can be applied for large values of n, but the maximum n which has been used by the existing methods are only n = 10, moreover our method is accurate and stable for different values of n.