فهرست مطالب

  • Volume:5 Issue:2, 2013
  • تاریخ انتشار: 1392/02/20
  • تعداد عناوین: 10
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  • S. K. Ravi, A. K. Singh, R. K. Singh, A. J. Chamkha Pages 87-95
    The aim of this paper is to present numerically the transport mechanism of an incompressible microp-olar uid between two vertical walls when the motion occurs due to the buoyancy force. The governing equations in non-dimensional form are solved numerically using the Matlab software. The obtained numerical solutions for the velocity and micro-rotation pro les are displayed using the graphs for various values of the vortex viscosity parameter and material parameter. It is found that the material parameter has retarding e ect on the velocity of micropolar uid and to make the ow steady state earlier for both thermal conditions. The e ect of the vortex viscosity parameter is to decrease the steady state time of the velocity and micro-rotation.
    Keywords: Micropolar uid, Matlab R2008a, Vertical walls, Unsteady ow
  • M. Gr. Voskoglou Pages 97-108
    In the present paper we use principles of fuzzy logic to develop a general model representing several processes in a systems operation characterized by a degree of vagueness and/or uncertainty. We also introduce three alternative measures of a fuzzy systems e ectiveness connected to our general model. These measures include the systems total possibilistic uncertainty, the Shannons entropy properly modi ed for use in a fuzzy environment and the centroid method in which the coordinates of the center of mass of the graph of the membership function involved provide an alternative measure of the systems performance. The advantages and disadvantages of the above measures are discussed and a combined use of them is suggested for achieving a worthy of credit mathematical analysis of the corresponding situation. Finally, an application of is presented for the Problem Solving process illustrating the use of our results in practice.
    Keywords: Systems theory, Fuzzy sets, logic, Possibility, Uncertainty theory, Problem solving
  • M. Azhini, N. Haddadzadeh Pages 109-118
    In this paper, we introduce fusion frames in Hilbert modules over pro-C*-algebras. Also, we give some useful results about these frames.
    Keywords: Pro, C*, algebra, Hilbert modules, Bounded module maps, Fusion frames
  • R. Saneifard, S. Nahid Pages 119-128
    Ranking of fuzzy numbers play an important role in decision making, optimization, forecasting etc.Fuzzy numbers must be ranked before an action is taken by a decision maker. The main aim of this paper is to propose a new approach for the ranking of generalized fuzzy numbers. The proposed ranking approach is based on distance between positive ideal solution and negative ideal solution. The main advantage of the proposed approach is that it provides the correct ordering of generalized and normal fuzzy numbers and it is very simple and easy to apply in the real life problems. The approach is illustrated by numerical examples, showing that it overcomes several shortcomings such as the indiscriminative and counterintuitive behavior of existing fuzzy ranking approaches.
    Keywords: Fuzzy numbers, Ranking fuzzy numbers, Ideal solutions, Distance
  • Sh. S. Behzadi Pages 129-141
    The Degasperis-Procesi equation can be derived as a member of a oneparameter family of asymptotic shallow water approximations to the Euler equations with the same asymptotic accuracy as that of the Camassa- Holm equation. In this paper, the Degasperis-Procesi equation is solved by using the Adomian's decomposition method, modi ed Adomian's decomposition method, variational iteration method, modi ed variational iteration method, homotopy perturbation method, modi ed homotopy perturbation method and homotopy analysis method. The existence and uniqueness of the solution and convergence of the proposed methods are proved in details. Finally an example shows the accuracy of these methods.
    Keywords: Degasperis, Procesi equation, Adomian decomposition method (ADM), Modi ed Adomian decomposition method (MADM), Variational iteration method (VIM), Modi ed variational iteration method (MVIM), Homotopy perturbation method (HPM), Modi ed homotopy perturbation method (MHPM)
  • Mojtaba Ghanbari, Rahele Nuraei Pages 143-147
    In this paper, we show that the computed distance between two fuzzy numbers using the fuzzy distance measure proposed by Chakraborty et al. [Mathematical and Computer Modelling 43 (2006) 254 261] is not always a fuzzy number. Then, we improve it and prove that the result of the revised distance is always a nonnegative fuzzy number.
    Keywords: Fuzzy distance measure, Generalized fuzzy number, LR, type fuzzy number
  • G. R. Jahanshahloo, I. Roshdi, M. Davtalab, Olyaie Pages 149-159
    In DEA (Data Envelopment Analysis), the Full Dimensional Ecient Facets (FDEFs) of PPS (Production Possibility Set) play a signi cant role and have many useful applications. In this research, we, rst, provide a detailed characterization of the structure of FDEFs of the PPS with constant returns to scale technology, using basic concepts of the polyhedral sets theory. Then, using the mentioned characterization together with a mixed integer linear programming, we propose an e ective algorithm for nding all of the FDEFs of the PPS. We will elaborate on our algorithm by an illustrative example.
    Keywords: Data envelopment analysis, Production possibility set, Weights, multipliers, Fulldimensional ecient facet, Polyhedral set, Mixed integer linear programming
  • P. Salehi, M. Nejatiyan Pages 161-165
    In this paper, a numerical method is proposed for solving the fuzzy linear Fredholm integral equations of the second kind. For this result, we choose Legendre polynomials as basis functions and collocation method to estimate a solution for an unknown function in these equations. Finally, a numerical example will be stated to illustrate this method.
    Keywords: Fuzzy number, Fuzzy Fredholm integral equation, Collocation method, Legendre polynomials
  • Zahra Masouri, Saeed Hatamzadeh, Varmazyar Pages 167-173
    The focus of this article is on the analysis of electromagnetic scattering from conducting bodies in TE polarization. For modeling of such problems, the magnetic field integral equation is used and the current density induced on the surface of scatterer is considered as the solution of the mentioned integral equation. A numerical approach is surveyed for calculating the induced current density because it has no analytical form, in general. Finally, three scattering structures are analyzed and the current density plots are given for them.
    Keywords: Magnetic field integral equation, Two, dimensional electromagnetic scattering, Integral equation modeling, Current distribution, Numerical evaluation
  • Sohrab Kordrostami, Omme Habibeh Azmayandeh Pages 175-185
    In the real world, there are production network which are composed of a set of the production processes, so that each production process have several interdependent subunits. In this paper, we consider dynamic networks which are composed of a set of production systems with parallel subunits, so that each subunit at any period uses of exogenous inputs and pervious period outputs to product the nal outputs and intermediate outputs. Then, we will proposed a model that focuses on the evaluating the performance of production systems across time and the calculating of the eciency of the whole system and subunits at each period.
    Keywords: DEA, Dynamic network, Parallel Production System, Statistical Analysis