Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
SPATIOTEMPORAL DYNAMIC OF TOXIN PRODUCING PHYTOPLANKTON (TPP)-ZOOPLANKTON INTERACTION
189
197
EN
A. K.
Sharma
Department of Mathematics, DAV College Jagraon, India
A.
Sharma
Department of Applied Sciences, DAV Institute of Engineering and Technology,
Jalandhar, India
K.
Agnihotri
Department of Applied Sciences, SBSSTC, Ferozpur, India.
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.
Toxin producing phytoplankton,zooplankton,Hopf Bifurcation,Turing instability,Normal Form,Center manifold theorem
http://ijm2c.iauctb.ac.ir/article_523826.html
http://ijm2c.iauctb.ac.ir/article_523826_ee389e29b10941031811506a49c93d4f.pdf
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
EFFICIENCY MEASUREMENT OF NDEA WITH INTERVAL DATA
199
210
EN
S.
Keikha- Javan
Department of Mathematics, Zabol Branch, Islamic Azad University, Zabol, Iran
M.
Rostamy-Malkhalifeh
Department of Mathematics, Science and Research Branch, Islamic Azad University,
Tehran, Iran
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.
DEA,Network DEA,Interval Data,divisional efficiency,overall efficiency
http://ijm2c.iauctb.ac.ir/article_523827.html
http://ijm2c.iauctb.ac.ir/article_523827_e94e16390891564ab2783605b6adbd09.pdf
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
APPLICATION OF THE RANDOM MATRIX THEORY ON THE CROSS-CORRELATION OF STOCK PRICES
211
219
EN
F.
Sotoude Vanoliya
Department of Statistics, University of Mazandaran, Iran
A.
Pourdarvish Heydari
Department of Statistics, University of Mazandaran, Iran
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.
Random Matrix Theory,Cross-Correlation,Eigenvalue and eigenvector
http://ijm2c.iauctb.ac.ir/article_523828.html
http://ijm2c.iauctb.ac.ir/article_523828_5f000bf7ebc56dd5aa2dc2ba58c0bad9.pdf
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
NUMERICAL SOLUTION OF DELAY INTEGRAL EQUATIONS BY USING BLOCK PULSE FUNCTIONS ARISES IN BIOLOGICAL SCIENCES
221
231
EN
M.
Nouri
Department of Mathematics, South Tehran Branch, Islamic Azad University, Tehran,
Iran
K.
Maleknejad
Department of Mathematics, Iran University of Science and Technology, Narmak,
Tehran, Iran
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.
Block pulse functions,Delay operational matrix.Block pulse functions,Operational matrix,Integral equations with time delay,Delay operational matrix
http://ijm2c.iauctb.ac.ir/article_523829.html
http://ijm2c.iauctb.ac.ir/article_523829_f4ddaee33533b2529bacc92c2fea6da9.pdf
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
NUMERICAL ANALYSIS OF THE CASIMIR EFFECT DUE TO A SCALAR FIELD
233
241
EN
A.
Ghaffari
Department of Physics, Islamic Azad University, Central Tehran Branch, PO. Code
14168-94351, Iran.
M. R.
Tanhayi
Department of Physics, Islamic Azad University, Central Tehran Branch, PO. Code
14168-94351, Iran.
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. eararqr
http://ijm2c.iauctb.ac.ir/article_523830.html
http://ijm2c.iauctb.ac.ir/article_523830_077f8f21e192c9bea21410b25924f12c.pdf
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
APPLICATION OF THE BELLMAN AND ZADEH'S PRINCIPLE FOR IDENTIFYING THE FUZZY DECISION IN A NETWORK WITH INTERMEDIATE STORAGE
243
252
EN
Mohammad
Rahimian
Department of Mathematics, Islamic Azad University, Masjed-Soleiman Branch,
Masjed-Soleiman, Iran
Esmaiel
Keshavarz
Department of Mathematics, Islamic Azad University, Sirjan Branch, Sirjan, Iran;
Hamid
Hassasi
Faculty of Management Sciences, Islamic Azad University, Central Tehran Branch,
Tehran, Iran
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.
multiple criterion optimization,best shipping pattern,Fuzzy number,Bellman-Zadeh's principle
http://ijm2c.iauctb.ac.ir/article_523831.html
http://ijm2c.iauctb.ac.ir/article_523831_f019e26acf19f2f5ad75e0b644f8999b.pdf
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
6
3 (Summer)
2016
07
01
GENERALIZATION OF TITCHMARSH'S THEOREM FOR THE GENERALIZED FOURIER-BESSEL TRANSFORM
253
260
EN
S.
El ouadih
Department of Mathematics, Faculty of Sciences A¨ın Chock,University Hassan II,
Casablanca, Morocco;
R.
Daher
Department of Mathematics, Faculty of Sciences A¨ın Chock,University Hassan II,
Casablanca, Morocco
M.
El hamma
Department of Mathematics, Faculty of Sciences A¨ın Chock,University Hassan II,
Casablanca, Morocco.
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.
singular dierential operator,generalized translation operatorsingular dierential operator,generalized Fourier-Bessel transform,generalized translation operator
http://ijm2c.iauctb.ac.ir/article_523832.html
http://ijm2c.iauctb.ac.ir/article_523832_fa3e099859720b33938360ff8cfb28f1.pdf