مجله بین المللی ریاضیات صنعتی
سال:1389 | دوره: | شماره: |تعداد مقالات:8

An analysis is carried out analytically to study steady heat and mass transfer by mixed convection flow of a viscous, incompressible, electrically-conducting and radiating fluid which is an optically thin gray gas, along a vertical porous plate under the action of transverse magnetic field taking into account the induced magnetic field with viscous dis-sipation of energy. The presence of a homogeneous chemical reaction of first order is also taken into account. The porous plate is subjected to a constant suction velocity as well as a uniform free stream velocity. The boundary layer equations have been transformed into dimensionless coupled non-linear ordinary differential equations by using appropriate transformations. The similarity solutions of the transformed dimensionless equations for the flow field, induced magnetic field, current density and heat and mass transfer charac-teristics are obtained by series solution technique and their numerical results are presented in the form of graphs. It is found that the velocity is reduced considerably with a rise in the conduction-radiation parameter (R) whereas the temperature is found to be markedly boosted with an increase in the conduction-radiation or the chemical reaction parameter (K). An increase in the magnetic body parameter (M) or chemical reaction rate (K) is found to escalate the induced magnetic field whereas an increase in the conduction-radiation parameter (R) or the magnetic Prandtl number (Pm) is shown to exert the opposite effect. Similarly, the current density (J) and the shear stress (G) are both consid- erably increased with an increase in the magnetic Prandtl number. Possible applications of the present study include laminar magneto-aerodynamics, materials processing and MHD propulsion thermo-fluid dynamics.

Data Envelopment Analysis (DEA) is a nonparametric mathematical programming approach for evaluating efficiency of a set of decision making units (DMUs). Since the number of efficient DMUs is more than one, there is a necessity of having methods to discriminate between efficient DMUs. In classic DEA it is assumed that data have deterministic values. Through real world applications this assumption may not be satisfied. On the other hand, data may have stochastic essence. In this paper a method for ranking stochastic DMUs is suggested which is based on the reliability of efficiency of DMUs. Using numerical example, we demonstrate how to use the results.

Recently, it has been obtained a lot of results on hyperconvex space (see [1, 2, 3, 5]). In this paper we develop some of those results for modular hyperconvex spaces.

In this paper, the laplace transform formula on the fuzzy two order derivative is investigated by using the strongly generalized differentiability concept. Then, it is used in a analytic method for fuzzy two order differential equation. The related theorems and properties are proved in detail and the method is illustrated by solving some examples.

In this paper, the variational iteration method is proposed to solve the Nagumo telegraph equation as boundary value problems over the finite spatial interval x Î [0, L], and finite time t Î [0, t*]. Approximate solution is obtained for some special cases, so that denotes the validity of the variational iteration method. Also, this approximate solution is used to discuss the qualitative characteristics of the solution for specific initial data considered.

The propose of this paper is to introduce a new fuzzy distance measure for fuzzy numbers. It computes the fuzzy distance between two fuzzy numbers. The metric properties of the proposed measure are also discussed in detail. Some numerical examples for computational implementation of the proposed method are also given.

In this paper, first, we propose Kaucher arithmetic for interval number and then solve the system A2n×nXn×1=b2n×1 where aij= [ai,j,`ai,j] and xj= [xj,`xj] and bi= [bi,`bi] based on Kaucher arithmetic such that ai,j .`ai,j ³ 0. Then, we extend this method by use of a- level set for fully fuzzy system of A~2n×nX~n×1= b~2n×1.

Inventory classification using ABC analysis is one of the most widely employed techniques in organizations. The need to consider multiple criteria for inventory classification is stressed in the literature. A DEA approach is proposed in this paper for computing most favourable and least favourable sets of weights in multiple-criteria inventory classification. To illustrate the model capability the proposed methodology is applied to a real data set consisting of the 47 items.