JMM دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Entropy generation due to unsteady hydromagnetic Couette flow and heat transfer with asymmetric convective cooling in a rotating system Entropy generation due to unsteady hydromagnetic Couette flow Das Sanatan Department of Mathematics, University of Gour Banga Malda 732 103, West Bengal, India Jana Rabindranath Department of Applied Mathematics, Vidyasagar University Midnapore 721 102, West Bengal, India Chamkha Ali J. Mechanical Engineering Department, Prince Mohammad Bin Fahd University (PMU), Al-Khobar 31952, Kingdom of Saudi Arabia 01 03 2016 3 2 111 128 30 07 2015 30 07 2015 Copyright © 2016, دانشگاه گیلان. 2016 https://jmm.guilan.ac.ir/article_1216.html

Entropy generation in an unsteady hydromagnetic Couette flow of a viscous incompressible electrically conducting fluid between two infinite horizontal parallel plates in a rotating system have been analyzed. Both the lower and upper plates of the channel are subjected to asymmetric convective heat exchange with the ambient following the Newton's law of cooling. A numerical solution for governing equations is developed. The influences of the pertinent parameters on the fluid velocity components, temperature, entropy generation and Bejan number are discussed graphically.

Couette flow convective cooling entropy generation and Bejan number
JMM دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper An efficient algorithm for finding the semi-obnoxious \$(k,l)\$-core of a tree Efficient algorithm for finding the semi-obnoxious \$(k,l)\$-core of a tree Motevalli Samane Faculty of Mathematics, Shahrood University, Shahrood, Iran Fathali Jafar Faculty of Mathematics, Shahrood University, Shahrood, Iran Zaferanieh Mehdi Department of Mathematics, Hakim Sabzevari University, Sabzevar, Iran 01 03 2016 3 2 129 144 30 07 2015 30 07 2015 Copyright © 2016, دانشگاه گیلان. 2016 https://jmm.guilan.ac.ir/article_1217.html

In this paper we study finding the \$(k,l)\$-core problem on a tree which the vertices have positive or negative weights. Let \$T=(V,E)\$ be a tree. The \$(k,l)\$-core of \$T\$ is a subtree with at most \$k\$ leaves and with a diameter of at most \$l\$ which the sum of the weighted distances from all vertices to this subtree is minimized. We show that, when the sum of the weights of vertices is negative, the \$(k,l)\$-core must be a single vertex. Then we propose an algorithm with time complexity of \$O(n^2log n)\$ for finding the \$(k,l)\$-core of a tree with pos/neg weight, which is in fact a modification of the one proposed by Becker et al. [Networks 40 (2002) 208].

Core Facility location Median subtree Semi-obnoxious
JMM دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Effects of Hall current and ion-slip on unsteady hydromagnetic generalised Couette flow in a rotating Darcian channel Effects of Hall current and ion-slip on ... Kumar Singh Jitendra Department of Mathematics, V. S. K. University, Bellary-583105, India Ghousia Begum Shaik Department of Mathematics, V. S. K. University, Bellary-583105, India Joshi Naveen Department of Mathematics, V. S. K. University, Bellary-583105, India 01 03 2016 3 2 145 167 22 08 2015 22 08 2015 Copyright © 2016, دانشگاه گیلان. 2016 https://jmm.guilan.ac.ir/article_1249.html

Unsteady hydromagnetic generalised Couette flow of a viscous, incompressible and electrically conducting fluid between two horizontal parallel porous plates Darcian channel in the presence of a uniform transverse magnetic field taking Hall current and ion-slip into account in a rotating system is investigated. An exact solution of the governing equations is obtained by Laplace transform technique. The expression for the shear stress at the moving porous plate due to primary and secondary flows is also derived. Asymptotic behavior of the solution is analyzed at the start-up and final stage of the motion to gain some physical insight into the flow pattern. Numerical values of primary and secondary velocities and that of shear stress at the moving porous plate of the channel due to primary and secondary flows are displayed graphically for various values of different flow parameters.

Hall current ion-slip Rotation permeability suction/injection
JMM دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Simulation of particle diffusion and heat transfer in a two-phase turbulent boundary layer using the Eulerian-Eulerian approach Simulation of particle diffusion and heat transfer Tripathy Pradeep Kumar Department of Mathematics and Science, U.C.P. Engg. School, Berhampur - 760 010, Dist. Ganjam, Odisha, India Mishra Saroj Kumar Khallikote - 761030, Dist. Ganjam, Odisha, India Chamkha Ali Jawad Prince Mohammad Bin Fahd University (PMU), P.O. Box 1664, Al-Khobar 31952, Kingdom of Saudi Arabia 01 03 2016 3 2 169 187 11 10 2015 11 10 2015 Copyright © 2016, دانشگاه گیلان. 2016 https://jmm.guilan.ac.ir/article_1316.html

This work investigates the response of two-dimensional, turbulent boundary layer characteristics over a flat plate to the presence of suspended particulate matter. Both phases are assumed to be interacting continua. That is, the carrier fluid equations are considered to be coupled with the particle-phase equations. A finite-difference technique with non-uniform grid has been employed for the solution of the governing equations and therefore, interpretation of the results and comparison of the present result with the results of other references. The results clearly demonstrate that the presence of particles damped the fluid turbulence and apparently affects the skin friction and heat transfer characteristics equally.

Particulate suspensions turbulent boundary layer characteristics flat plate finite difference techniques shear stress heat transfer
JMM دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper A model for the dynamical study of food-chain system considering interference of top predator in a polluted environment Dynamical Study of Food--Chain System... Misra Om Prakash School of Mathematics and Allied Sciences, Jiwaji University, Gwalior-474 011, India Annavarapu Raveendra Babu School of Mathematics and Allied Sciences, Jiwaji University, Gwalior-474 011, India 01 03 2016 3 2 189 218 28 09 2015 10 12 2015 Copyright © 2016, دانشگاه گیلان. 2016 https://jmm.guilan.ac.ir/article_1471.html

The modeling investigation in this paper discusses the system level effects of a toxicant on a three species food chain system. In the models, we have assumed that the presence of top predator reduces the predatory ability of the intermediate predator. The stability analysis of the models is carried out and the sufficient conditions for the existence and extinction of the populations under the stress of toxicant are obtained. Further, it is also found that the predation rate of the intermediate predator is a bifurcating parameter and Hopf-bifurcation occurs at some critical value of this parameter. Finally, numerical simulation is carried out to support the analytical results.

Stability Bifurcation Interference Lyapunov function
JMM دانشگاه گیلان Journal of Mathematical Modeling 2345-394X دانشگاه گیلان 17 Research Paper Spline Collocation for system of Fredholm and Volterra integro-differential equations System of Fredholm and Volterra integro-differential equations Ebrahimi Nehzat Department of Mathematics, Islamic Azad University, Central Tehran Branch, Iran Rashidinia Jalil Department of Mathematics, Islamic Azad University, Central Tehran Branch, Iran 01 03 2016 3 2 189 218 19 01 2016 19 01 2016 Copyright © 2016, دانشگاه گیلان. 2016 https://jmm.guilan.ac.ir/article_1502.html

The spline collocation method  is employed to solve a system of linear and nonlinear Fredholm and Volterra integro-differential equations. The solutions are collocated by cubic B-spline and the integrand is approximated by the Newton-Cotes formula. We obtain the unique solution for linear and nonlinear system \$(nN+3n)times(nN+3n)\$ of integro-differential equations. This approximation reduces the system of integro-differential equations to an explicit system of algebraic equations. At the end, some examples are presented to illustrate the ability and simplicity of the method.

System of Fredholm and Volterra integro-differential equations Cubic B-spline Newton-Cotes formula Convergence analysis