Browsing by Author "Khan, Muhammad Altaf"

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A theoretical model for Zika virus transmission
(PLoS ONE, 2017-10-04) Bonyah, Ebenezer; Khan, Muhammad Altaf; Okosun, K.O; Islam, Saeed
In this paper, we present and analyze an SEIR Zika epidemic model. Firstly, we investigate the model with constant controls. The steady states of the model is found to be locally and globally asymptotically stable. Thereafter, we incorporate time dependent controls into the model in order to investigate the optimal effects of bednets, treatments of infective and spray of insecticides on the disease spread. Furthermore, we used Pontryagin’s Maximum Principle to determine the necessary conditions for effective control of the disease. Also, the numerical results were presented
Double-layer optical fiber coating analysis in MHD flow of an elastico-viscous fluid using wet-on-wet coating process
(Elsevier, 2016-12-05) Khan, Zeeshan; Islam, Saeed; Shah, Rehan Ali; Khan, Muhammad Altaf; Bonyah, Ebenezer; Jan, Bilal; Khan, Aurangzeb
Modern optical fibers require a double-layer coating on the glass fiber in order to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical f ibers are plastic polyvinyl chloride (PVC) and low and high density polyethylene (LDPE/HDPE), nylon and Polysulfone. One of the most important things which affect the final product after processing is the design of the coating die. In the present study, double-layer optical fiber coating is performed using melt poly mer satisfying Oldroyd 8-constant fluid model in a pressure type die with the effect of magneto hydrodynamic (MHD). Wet-on-wet coating process is applied for double-layer optical fiber coating. The coating process in the coating die is modeled as a simple two-layer Couette flow of two immiscible f luids in an annulus with an assigned pressure gradient. Based on the assumptions of fully developed laminar and MHD flow, the Oldroyd 8-constant model of non-Newtonian fluid of two immiscible resin layers is modeled. The governing nonlinear equations are solved analytically by the new technique of Optimal Homotopy Asymptotic Method (OHAM). The convergence of the series solution is established. The results are also verified by the Adomian Decomposition Method (ADM). The effect of important parameters such as magnetic parameter Mi, the dilatant constant a, the Pseodoplastic constant b, the radii ratio d, the pressure gradient X, the speed of fiber optics V, and the viscosity ratio j on the velocity profiles, thickness of coated fiber optics, volume flow rate, and shear stress on the fiber optics are inves tigated. At the end the result of the present work is also compared with the experimental results already available in the literature by taking non-Newtonian parameters tends to zero. 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND
The electrical MHD and Hall current impact on micropolar nanofluid f low between rotating parallel plates
(Elsevier, 2018-02-02) Shah, Zahir; Islam, Saeed; Gul, Taza; Bonyah, Ebenezer; Khan, Muhammad Altaf
The current research aims to examine the combined effect of magnetic and electric field on micropolar nanofluid between two parallel plates in a rotating system. The nanofluid flow between two parallel plates is taken under the influence of Hall current. The flow of micropolar nanofluid has been assumed in steady state. The rudimentary governing equations have been changed to a set of differential nonlinear and coupled equations using suitable similarity variables. An optimal approach has been used to acquire the solution of the modelled problems. The convergence of the method has been shown numerically. The impact of the Skin friction on velocity profile, Nusslet number on temperature profile and Sherwood number on concentration profile have been studied. The influences of the Hall currents, rotation, Brownian motion and thermophoresis analysis of micropolar nanofluid have been mainly focused in this work. Moreover, for comprehension the physical presentation of the embedded parameters that is, cou pling parameter N1 , viscosity parameter Re, spin gradient viscosity parameter N2, rotating parameter Kr, Micropolar fluid constant N3, magnetic parameter M, Prandtl number Pr, Thermophoretic parameter Nt, Brownian motion parameter Nb, and Schmidt number Sc have been plotted and deliberated graphically. 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)