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Zain-Ul-Abdein M.,Ghulam Ishaq Khan Institute of Engineering Sciences and Technology | Azeem S.,UET Peshawar | Shah S.M.,University of Lyon
International Journal of Engineering Science

Particulate filled polymeric composites with enhanced thermo-physical properties are highly demanded in electronic industry. This paper presents an experimental and computational investigation of the thermal conductivity enhancement in a bakelite-graphite composite material. The experimental work illustrates an effect of the graphite addition in different volume fractions upon the effective thermal conductivity of the composite. Computational investigation was performed in two parts. The first part explains a development of experimentally validated finite element models for the estimation of effective thermal conductivity, while the second part demonstrates a detailed analysis of the factors affecting thermal conductivity of the composite. The factors that were examined include particle size with individual constituent properties, and air gaps/voids and interface additions in terms of packing density. The findings showed that not only the finite element simulations may be exploited for the prediction of effective thermal conductivity in a composite material; they may also be helpful in suggesting the optimum particle size and packing density factors to suit the industrial design requirements. © 2012 Elsevier Ltd. All rights reserved. Source

Amin N.-U.,Abdul Wali Khan University Mardan | Alam S.,University of Malakand | Gul S.,UET Peshawar
RSC Advances

Natural kaolinitic clay from Khyber Pakhtoonkhwa, Pakistan was thermally activated at different temperatures and its pozzolanic behavior was studied. Thermal activation was carried out in an electrical muffle furnace at 200, 400, 600 and 800 °C for two hours. The index of order/disorder and structural changes with thermal treatment were studied using X-ray diffraction (XRD) and Fourier transformed infra-red spectrometry (FTIR). The pozzolanic behavior of all the samples was evaluated using an electrical conductivity test, lime consumption (LC) test and strength activity index (SAI). This study confirmed that natural kaolinitic clay other than pure kaolinite can act as an interesting pozzolana when thermally activated. The best temperature for thermal treatment of natural kaolinitic clay is 800°C, while the permissible replacement in mortar is 25% as confirmed from the compressive strength measurement. This journal is © The Royal Society of Chemistry. Source

Gul T.,Abdul Wali Khan University Mardan | Islam S.,Abdul Wali Khan University Mardan | Shah R.A.,UET Peshawar | Khan I.,University of Technology Malaysia | Shafie S.,Majmaah University

In this work, we have carried out the influence of temperature dependent viscosity on thin film flow of a magnetohydrodynamic (MHD) third grade fluid past a vertical belt. The governing coupled non-linear differential equations with appropriate boundary conditions are solved analytically by using Adomian Decomposition Method (ADM). In order to make comparison, the governing problem has also been solved by using Optimal Homotopy Asymptotic Method (OHAM). The physical characteristics of the problem have been well discussed in graphs for several parameter of interest. © 2014 Gul et al. Source

Khan N.,UET Peshawar | Fekri S.,Cranfield University | Ahmad R.,University of Leicester | Gu D.,University of Leicester
Proceedings of the IEEE Conference on Decision and Control

In this paper, an integrated attitude estimation and control algorithm is addressed and implemented to a spacecraft dynamical model subject to observation (sensor) losses. Rigid body equations of motion for modeling and control of spacecraft model is obtained from both kinematic and dynamic equations. An earlier version of the so-called closed-loop estimation scheme presented in [9] is extended and implemented to the spacecraft model subject to observation losses. Compensated observation signals are reconstructed based on linear prediction subsystem and utilized at measurement update steps. Simulation results verify that the proposed robust estimation algorithm applied to the rigid body spacecraft model significantly outperforms existing open-loop filtering algorithms and could attack many other practical applications with intermittent output measurement losses. © 2011 IEEE. Source

Ullah A.,Loughborough University | Khan S.W.,Loughborough University | Shakoor A.,UET Peshawar | Starov V.M.,UET Peshawar
Separation and Purification Technology

The model presented in the paper is the continuation of the previous work where a mathematical model was developed for the passage and deformation of micro-sized oil drops through a 4 μm converging slotted pore membrane. In the previous work, it was assumed that drops deform from a spherical shape to a prolate spheroid when pass through a converging slot. In the present study, it has been assumed that drops deform into an oblate spheroid while passing through a non-converging slot and a mathematical model is developed for the deformation of drops through non-converging slots. After extending the idea of static and drag forces, it is readily seen that the magnitude of static force (F cx) for the non-converging slotted pore membrane is higher than the static force (Fcxâ̂ -) for the converging slotted pore membranes. This is because of drops deform suddenly in the non-converging slots, while, in case of converging slots, the drops deform gradually. Micro-sized oil drops of two systems with different interfacial tensions (4 and 9 mN/m) have been used in the study and it is observed that a higher interfacial tension leads to a higher rejection rate for both converging and non-converging slotted pore membranes at various in-pore filtration velocities. © 2013 Elsevier Ltd. All rights reserved. Source

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