International Journal of Mathematical Modelling & ComputationsInternational Journal of Mathematical Modelling & Computations
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Feed provided by International Journal of Mathematical Modelling & Computations. Click to visit.SPATIOTEMPORAL DYNAMIC OF TOXIN PRODUCING PHYTOPLANKTON (TPP)-ZOOPLANKTON INTERACTION
http://ijm2c.iauctb.ac.ir/article_523826_112365.html
The present paper deals with a toxin producing phytoplankton (TPP)-zooplankton interaction in spatial environment in thecontext of phytoplankton bloom. In the absence of diffusion the stability of the given system in terms of co-existence and hopf bifurcation has been discussed. After that TPP-zooplankton interaction is considered in spatiotemporal domain by assuming self diffusion in both population. It has been obtained that in the presence of diffusion given system becomes unstable (Turing instability) under certain conditions. Moreover, by applying the normal form theory and the center manifold reduction for partial differential equations (PDEs), the explicit algorithm determining the direction ofHopf bifurcations and the stability of bifurcating periodic solutions is derived. Finally, numericalsimulations supporting the theoretical analysis are also included.Thu, 30 Jun 2016 19:30:00 +0100Jacobi Operational Matrix Approach for Solving Systems of Linear and Nonlinear ...
http://ijm2c.iauctb.ac.ir/article_527368_0.html
‎‎‎‎‎‎‎‎‎‎‎‎‎This paper aims to construct a general formulation for the shifted Jacobi operational matrices of integration and product‎. ‎The main aim is to generalize the Jacobi integral and product operational matrices to the solving system of Fredholm and Volterra integro--differential equations‎ which appear in various fields of science such as physics and engineering. ‎The Operational matrices together with the collocation method are applied to reduce the solution of these problems to the solution of a system of algebraic equations‎. ‎ Indeed, to solve the system of integro-differential equations, a fast algorithm is used for simplifying the problem under study. ‎The method is applied to solve system of linear and nonlinear Fredholm and Volterra integro-differential equations‎. ‎Illustrative examples are included to demonstrate the validity and efficiency of the presented method‎. It is further found that the absolute errors are almost constant in the studied interval. ‎Also‎, ‎several theorems related to the convergence of the proposed method‎, ‎will be presented‎‎.‎Thu, 12 Jan 2017 20:30:00 +0100EFFICIENCY MEASUREMENT OF NDEA WITH INTERVAL DATA
http://ijm2c.iauctb.ac.ir/article_523827_112365.html
Data envelopment analysis (DEA) is a non-parametric technique for evaluation of relative efficiency of decision making units described by multiple inputs and outputs. It is based on solving linear programming problems. Since 1978 when basic DEA model was introduced many its modifications were formulated. Among them are two or multi-stage models with serial or parallel structure often called network DEA models that are widely discussed in professional community in the last years. The exact known inputs and outputs are required in these DEA models. However, in the real world, the concern is systems with interval (bounded) data. When we incorporate such interval data into multi-stage DEA models, the resulting DEA model becomes a non-linear programming problem. In this study, we suggest an approach to measure the efficiency of series and parallel systems with interval data that preserves the linearity of DEA model. Also, the interval DEA models are proposed to measure the lower and upper bounds of the efficiency of each DMU with interval data.Thu, 30 Jun 2016 19:30:00 +0100APPLICATION OF THE RANDOM MATRIX THEORY ON THE CROSS-CORRELATION OF STOCK ā€ˇPRICES
http://ijm2c.iauctb.ac.ir/article_523828_112365.html
The analysis of cross-correlations is extensively applied for understanding of interconnections in stock markets. Variety of methods are used in order to search stock cross-correlations including the Random Matrix Theory (RMT), the Principal Component Analysis (PCA) and the Hierachical ‎Structures.‎
In ‎this work‎, we analyze cross-crrelations between price fluctuations of 20 ‎company ‎stocks‎‎ of Iran by using RMT. We find the eigenvalues and eigenvectors of the matrices of the cross-correlations related to ‎the‎se stocks.‎‎‎
The results show some eigenvalues do not fall within the bounds of RMT eigenvalues, that indicate the correlations of ‎‎ stocks in usual and critical flucatutions.Thu, 30 Jun 2016 19:30:00 +0100NUMERICAL SOLUTION OF DELAY INTEGRAL EQUATIONS BY USING BLOCK PULSE FUNCTIONS ARISES IN ...
http://ijm2c.iauctb.ac.ir/article_523829_112365.html
This article proposes a direct method for solving three types of integral equations with time delay. By using operational matrix of integration, integral equations can be reduced to a linear lower triangular system which can be directly solved by forward substitution. Numerical examples shows that the proposed scheme have a suitable degree of accuracy.
Thu, 30 Jun 2016 19:30:00 +0100NUMERICAL ANALYSIS OF THE CASIMIR EFFECT DUE TO A SCALAR FIELD
http://ijm2c.iauctb.ac.ir/article_523830_112365.html
In this paper, we study the Casimir effect of a scalar field with Dirichlet boundary condition in some certain topologies. By numerical analysis we show that Casimir energy is a shape-dependent quantity. We also obtain the phase transition in different topologies in which the Casimir force changes from attractive to repulsive or vice versa. eararqrThu, 30 Jun 2016 19:30:00 +0100APPLICATION OF THE BELLMAN AND ZADEH'S PRINCIPLE FOR IDENTIFYING THE FUZZY DECISION IN A ...
http://ijm2c.iauctb.ac.ir/article_523831_112365.html
In most of the real-life applications we deal with the problem of transporting some special fruits, as banana, which has particular production and distribution processes. In this paper we restrict our attention to formulating and solving a new bi-criterion problem on a network in which in addition to minimizing the traversing costs, admissibility of the quality level of fruits is a main objective. However, the fruits are possibly stored at some intermediate node for practical purposes. We call the new model the best shipping pattern problem with intermediate storage. Here, it is assumed that both arc costs and times are crisp numbers. The main contribution of this model is an actual interpretation of the given fuzzy trapezoidal number, as the quality of delivered commodities. Since the presented problem has a fuzzy structure, the Bellman and Zadeh's max-min criterion can be used to treat it as a crisp single-objective problem, which is easily solvable. An illustrative example is solved, to explain the presented details.Thu, 30 Jun 2016 19:30:00 +0100GENERALIZATION OF TITCHMARSH'S THEOREM FOR THE GENERALIZED FOURIER-BESSEL TRANSFORM
http://ijm2c.iauctb.ac.ir/article_523832_112365.html
In this paper, using a generalized translation operator, we prove theestimates for the generalized Fourier-Bessel transform in the space L2 on certainclasses of functions.Thu, 30 Jun 2016 19:30:00 +0100