Journal of Operational Research in its Applications
Year:2007 | Volume:4 | Issue:12|Papers Count:8

One of the topics of interest in data envelopment analysis (DEA) is sensitivity and stability analysis of the specific decision making unit (DMU) which is under evaluation. This paper, a method for obtaining input stability region of the specific decision making unit (DMU), is based on the increase of some or all the inputs and the decrease of some or all the outputs, when variations in the data are considered for a specific efficient DMU and the data for remaining  DMUs are assumed fixed.

In this paper, an algorithm for edge-coloring of simple graphs has been discussed. Simplicity and quality of this algorithm compare to other existing algorithms and the privileges are shown.

Linear Discriminate Analysis (LDA) is a valuable tool for two or multigroup classification. Assuming in LDA classes have multivariate normal distribution with common covariance matrix. The case of normal classes rarely holds. Therefore, for the purpose of effective classification in case of heterogeneity of classes it is natural to assume that the classes consist of subclasses with normal but unobserved distribution, classification in this case is called Mixture Discriminate Analysis (MDA), and estimation of the parameters is possible only through EM algorithm. Linear decision boundaries do not differentiate classes completely. In MDA, decision boundaries are nonlinear even with the assumption of equal covariance matrix among classes. This study with financial ratios  of Altman model tries to predict financial failure in Tehran stock market, for this purpose sample consist 100 survivor firms and 44 bankrupt firms from 1378 to 1384. Using this sample estimated parameters for LDA and compared MDA. It has been demonstrated MDA is more effective for predicting financial failure of various firms and MDA has been 92.34 percent correct classification for all firms.

In this paper a new method that is based on Back stepping Method is presented to control a class of nonlinear control systems. This method can be used for stabilization and tracking problem for a class of autonomous nonlinear systems. The model that can be described with this method covers many nonlinear control systems. With proposed method that can be called nonlinear state feedback, unstable states would be stabled. Simulations proved this case.

In this paper, we want to present a particular method to obtain the approximate solutions for the system of differential equations Lotka_Volterra near to one of its critical points, which is the kind of the center one, such where these solutions have good precisions and have periodic property.

In this paper, an inverse heat conduction problem has been considered. Mathematical model of this problem consists a parabolic equation in which one of the boundary conditions are unknown. Solving of this inverse problem requires determining the unknown boundary condition from an additional condition at the interior point of the region of problem. For determining the solution of this problem, we consider a numerical algorithm based on finite difference method. Stability and consistency of this numerical scheme will be proved. Some numerical examples will be given in the last section.

In the exploration for uranium, an important procedure is using airborne geophysical data collected -ray sensitive equipment on reconnaissance planes. Taking into account the way in which uranium is spread in the earth’s crust, a significant portion of the primary phase to exploration in the identification of anomalous ‘hot’ zones from the background. Fractal geometry employs a framework different from Euclidean geometry. It is also inspired by processed observed in nature. For these two reasons fractal geometry is used with logarithmic concentration-area charts derived from 10769 numeral data in unliq (an area in East azarbaijan province in Iran) was able to separate regions taking into account their background, threshold and anomalous degrees, from indexes obtained from concentration-area charts. Ultimately, maps of anomalous regions, and Uranium mineral indexes in the unliq region from the acquire fractal models is presented.

In this paper solving special Volterra integral Equations of the first kind with singular kernels will be studied. Also, we consider Abel's kernels. The simplicity and efficiency of the proposed method will be shown by some examples.