eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
189
197
523826
SPATIOTEMPORAL DYNAMIC OF TOXIN PRODUCING PHYTOPLANKTON (TPP)-ZOOPLANKTON INTERACTION
A. K. Sharma
1
A. Sharma
2
K. Agnihotri
3
Department of Mathematics, DAV College Jagraon, India
Department of Applied Sciences, DAV Institute of Engineering and Technology, Jalandhar, India
Department of Applied Sciences, SBSSTC, Ferozpur, India.
The present paper deals with a toxin producing phytoplankton (TPP)-zooplankton interaction in spatial environment in the<br />context 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 of<br />Hopf bifurcations and the stability of bifurcating periodic solutions is derived. Finally, numerical<br />simulations supporting the theoretical analysis are also included.
http://ijm2c.iauctb.ac.ir/article_523826_ee389e29b10941031811506a49c93d4f.pdf
Toxin producing phytoplankton
Zooplankton
Hopf Bifurcation
Turing instability
Normal Form
Center manifold theorem
eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
199
210
523827
EFFICIENCY MEASUREMENT OF NDEA WITH INTERVAL DATA
S. Keikha- Javan
1
M. Rostamy-Malkhalifeh
2
Department of Mathematics, Zabol Branch, Islamic Azad University, Zabol, Iran
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.
http://ijm2c.iauctb.ac.ir/article_523827_e94e16390891564ab2783605b6adbd09.pdf
DEA
Network DEA
Interval data
divisional efficiency
overall efficiency
eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
211
219
523828
APPLICATION OF THE RANDOM MATRIX THEORY ON THE CROSS-CORRELATION OF STOCK PRICES
F. Sotoude Vanoliya
1
A. Pourdarvish Heydari
2
Department of Statistics, University of Mazandaran, Iran
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.
http://ijm2c.iauctb.ac.ir/article_523828_5f000bf7ebc56dd5aa2dc2ba58c0bad9.pdf
random matrix theory
Cross-Correlation
Eigenvalue and eigenvector
eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
221
231
523829
NUMERICAL SOLUTION OF DELAY INTEGRAL EQUATIONS BY USING BLOCK PULSE FUNCTIONS ARISES IN BIOLOGICAL SCIENCES
M. Nouri
1
K. Maleknejad
2
Department of Mathematics, South Tehran Branch, Islamic Azad University, Tehran, Iran
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.
http://ijm2c.iauctb.ac.ir/article_523829_f4ddaee33533b2529bacc92c2fea6da9.pdf
Block pulse functions
Delay operational matrix.Block pulse functions
Operational matrix
Integral equations with time delay
Delay operational matrix
eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
233
241
523830
NUMERICAL ANALYSIS OF THE CASIMIR EFFECT DUE TO A SCALAR FIELD
A. Ghaffari
1
M. R. Tanhayi
2
Department of Physics, Islamic Azad University, Central Tehran Branch, PO. Code 14168-94351, Iran.
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_077f8f21e192c9bea21410b25924f12c.pdf
eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
243
252
523831
APPLICATION OF THE BELLMAN AND ZADEH'S PRINCIPLE FOR IDENTIFYING THE FUZZY DECISION IN A NETWORK WITH INTERMEDIATE STORAGE
Mohammad Rahimian
1
Esmaiel Keshavarz
2
Hamid Hassasi
3
Department of Mathematics, Islamic Azad University, Masjed-Soleiman Branch, Masjed-Soleiman, Iran
Department of Mathematics, Islamic Azad University, Sirjan Branch, Sirjan, Iran;
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.
http://ijm2c.iauctb.ac.ir/article_523831_f019e26acf19f2f5ad75e0b644f8999b.pdf
multiple criterion optimization
best shipping pattern
Fuzzy number
Bellman-Zadeh's principle
eng
Islamic Azad University, Central tehran Branch
International Journal of Mathematical Modelling & Computations
2228-6225
2228-6233
2016-07-01
6
3 (Summer)
253
260
523832
GENERALIZATION OF TITCHMARSH'S THEOREM FOR THE GENERALIZED FOURIER-BESSEL TRANSFORM
S. El ouadih
1
R. Daher
2
M. El hamma
3
Department of Mathematics, Faculty of Sciences A¨ın Chock,University Hassan II, Casablanca, Morocco;
Department of Mathematics, Faculty of Sciences A¨ın Chock,University Hassan II, Casablanca, Morocco
Department of Mathematics, Faculty of Sciences A¨ın Chock,University Hassan II, Casablanca, Morocco.
In this paper, using a generalized translation operator, we prove the<br />estimates for the generalized Fourier-Bessel transform in the space L2 on certain<br />classes of functions.
http://ijm2c.iauctb.ac.ir/article_523832_fa3e099859720b33938360ff8cfb28f1.pdf
singular dierential operator
generalized translation operatorsingular dierential operator
generalized Fourier-Bessel transform
generalized translation operator