J. Math. Model. دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper SDO relaxation approach to fractional quadratic minimization with one quadratic constraint SDO relaxation and fractional quadratic minimization Salahi Maziar Faculty of Mathematical Sciences, University of Guilan,Rasht, Iran Zare Arezo Faculty of Mathematical Sciences, University of Guilan,Rasht, Iran 01 06 2015 3 1 1 13 09 06 2015 09 06 2015 Copyright © 2015, دانشگاه گیلان. 2015 https://jmm.guilan.ac.ir/article_198.html

In this paper, we study the problem of minimizing the ratio of two quadratic functions subject to a quadratic constraint. First we introduce a parametric equivalent of the problem. Then a bisection and a generalized Newton-based method algorithms are presented to solve it. In order to solve the quadratically constrained quadratic minimization problem within both algorithms, a semidefinite optimization relaxation approach is presented. Finally, two set of examples are presented to compare the performance of algorithms.

Fractional quadratic optimization nonconvex problem convex optimization semidefinite optimization
J. Math. Model. دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Dynamical behavior and synchronization of hyperchaotic complex T-system Dynamical behavior and synchronization Kheiri Hossein Faculty of Mathematical Sciences, University of Tabriz, Tabriz, Iran Naderi Bashir Department of Mathematics, Payame Noor University, Iran 01 06 2015 3 1 15 32 09 06 2015 09 06 2015 Copyright © 2015, دانشگاه گیلان. 2015 https://jmm.guilan.ac.ir/article_196.html

In this paper, we introduce a new hyperchaotic complex T-system. This system has complex nonlinear behavior which we study its dynamical properties including invariance, equilibria and their stability, Lyapunov exponents, bifurcation, chaotic behavior and chaotic attractors as well as necessary conditions for this system to generate chaos. We discuss the synchronization with certain and uncertain parameters via adaptive control. For synchronization, we use less controllers than the dimension of the proposed system. Also, we prove that the error system is asymptotically stable by using a Lyapunov function. Numerical simulations are computed to check the analytical expressions.

Lyapunov stability Synchronization Chaos Adaptive control
J. Math. Model. دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper An efficient numerical method for singularly perturbed second order ordinary differential equation On the singularly perturbed second order ODE Mohapatra Jugal Department of Mathematics, National Institute of Technology Rourkela, India Mahalik Manas kumar Department of Mathematics, National Institute of Technology Rourkela, India 01 06 2015 3 1 33 48 09 06 2015 09 06 2015 Copyright © 2015, دانشگاه گیلان. 2015 https://jmm.guilan.ac.ir/article_197.html

In this paper an exponentially fitted finite difference method is presented for solving singularly perturbed two-point boundary value problems with the boundary layer. A fitting factor is introduced and the model equation is discretized by a finite difference scheme on an uniform mesh. Thomas algorithm is used to solve the tri-diagonal system. The stability of the algorithm is investigated. It is shown that the proposed technique is of first order accurate and the error constant is independent of the perturbation parameter. Several problems are solved and numerical results are presented to support the theoretical error bounds established.

Singular perturbation problems boundary layers Thomas algorithm exponential fitting factor uniform convergence
J. Math. Model. دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Hydromagnetic Couette flow of class-II and heat transfer through a porous medium in a rotating system with Hall effects Hydromagnetic Couette flow of class-II Shanker Seth Gauri Department of Applied Mathematics, Indian School of Mines, Dhanbad-826004, India Mandal Prashanta Kumar Department of Applied Mathematics, Indian School of Mines, Dhanbad-826004, India Sharma Rohit Department of Applied Mathematics, Indian School of Mines, Dhanbad-826004, India 01 06 2015 3 1 49 75 10 06 2015 10 06 2015 Copyright © 2015, دانشگاه گیلان. 2015 https://jmm.guilan.ac.ir/article_205.html

Steady hydromagnetic Couette flow of class-II of a viscous, incompressible and electrically conducting fluid through a porous medium in a rotating system taking Hall current into account is investigated. Heat transfer characteristics of the fluid flow are considered taking viscous and Joule dissipations into account. It is noticed that there exists flow separation at the moving plate in the secondary flow direction on increasing either rotation parameter \$K^2\$ when Hall current parameter \$m = 0.5\$ or \$m\$ when \$K^2 = 7\$. Also there exists flow separation at the moving plate in the secondary flow direction on increasing either magnetic parameter \$M^2\$ for every value of porosity parameter \$K_1\$ or \$K_1\$ when \$M^2 = 15\$.

Couette flow of class-II Porous medium Coriolis force Hall current viscous and Joule dissipations
J. Math. Model. دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Bernoulli matrix approach for matrix differential models of first-order On the solution of linear matrix differential equations Golbabai Ahmad School of Mathematics, Iran University of Science and Technology, Tehran, Iran Panjeh Ali Beik Samaneh School of Mathematics, Iran University of Science and Technology, Tehran, Iran 01 06 2015 3 1 77 89 09 06 2015 09 06 2015 Copyright © 2015, دانشگاه گیلان. 2015 https://jmm.guilan.ac.ir/article_201.html

The current paper contributes a novel framework for solving a class of linear matrix differential equations. To do so, the operational matrix of the derivative based on the shifted Bernoulli polynomials together with the collocation method are exploited to reduce the main problem to system of linear matrix equations. An error estimation of presented method is provided. Numerical experiments are reported to demonstrate the applicably and efficiency of the propounded technique.

Linear matrix differential equation Bernoulli polynomials operational matrix of derivative error estimation
J. Math. Model. دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Determining the order of minimal realization of descriptor systems without use of the Weierstrass canonical form Determining the order of minimal realization of descriptor systems Nassiri Pirbazari Kamele Faculty of Mathematical Sciences, University of Guilan, Rasht, Iran Azari Mehdi Faculty of Mathematical Sciences, University of Guilan, Rasht, Iran 01 06 2015 3 1 91 101 09 06 2015 09 06 2015 Copyright © 2015, دانشگاه گیلان. 2015 https://jmm.guilan.ac.ir/article_199.html

A common method to determine the order of minimal realization of a continuous linear time invariant descriptor system is to decompose it into slow and fast subsystems using the Weierstrass canonical form. The Weierstrass decomposition should be avoided because it is generally an ill-conditioned problem that requires many complex calculations especially for high-dimensional systems. The present study finds the order of minimal realization of a continuous linear time invariant descriptor system without use of the Weierstrass canonical form.

Descriptor system minimal realization Weierstrass canonical form