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Khan I.,Majmaah University
Journal of Molecular Liquids | Year: 2017

Magnetohydrodynamic (MHD) mixed convection channel flow of Molybdenum disulphide (MoS2) nanofluid inside vertical porous medium is investigated. Molybdenum disulphide nanoparticles are used in water as based fluid. Fluid slips at the lower wall of the channel. Molybdenum disulphide as solid nanoparticles is used in different shapes such as platelet, blade, cylinder, brick and spherical. The governing equations are modeled and then solved analytically using perturbation technique. Approximate solutions are obtained for velocity and temperature profiles. Graphical results are obtained through a computational software Mathcad and discussed for various embedded parameters. A comparative study for different shapes of molybdenum disulphide nanoparticles is provided graphically. It is found that MoS2 nanoparticles with blade and platelet shapes have shown the highest heat transfer rate compared to cylinder and brick shapes. Porosity and magnetic parameters have shown opposite effects on velocity, whereas velocity has shown increase with increasing slip. © 2017

Khabaz A.,Majmaah University
Archives of Civil and Mechanical Engineering | Year: 2017

The sliding of straight steel fiber within a hardened concrete matrix is considered as the final stage of the pull-out force resistance. If the fiber has enough embedment length and the load reaches the applicable maximal force, the fiber may reach its yield strength leaving some length in the concrete. The interfacial-failure in bond strength starts gradually through interfacial debonding, which develops forward until covering whole embedment length of the fiber in the concrete. Then the fiber starts in resisting the further forces by friction stresses which are generated through frictional sliding process. These friction stresses work as an interfacial-shear forces and aim to satisfy the balance with that further forces. The sum of shear stresses at the interface decreases gradually due to gradual decreasing in the remained length of the fiber inside the concrete, what causes gradual decreasing in the tensile load capacity until an overall fracture in the composite. In this research paper, a clarification and an analysis of the sliding mechanism are introduced through an experimental study. In addition to that, there is a comparison between experimental results and simulations results, where specific computer simulations are prepared to show the deformation shape for each of the fiber and the concrete, as well as a clarification of the failure reasons in the adhesion at the interface between the fiber and the concrete. At the last part of this paper, a dynamical analysis has been achieved using an analytical model, which represents each of the experimental cases and the computer simulations, as well as an appropriate formulas govern the effect of the friction have been written. © 2017 Politechnika Wrocławska

Huda Z.,Majmaah University | Edi P.,King Fahd University of Petroleum and Minerals
Materials and Design | Year: 2013

This article reviews the advances in the materials selection for applications in structures and engines of current and future supersonic aircrafts. A brief overview of configuration design of the supersonic aircrafts is first given; which also includes techniques to improve configuration design for future supersonic aircrafts. The operating and ambient environmental conditions during supersonic flight and the resulting material requirements have been discussed; and consequently various aerospace aluminum alloys, titanium alloys, superalloys, and composites have been recommended. Finally, a new materials-selection chart is presented that would enable aerospace designers to select appropriate materials for application in high-performance current and future supersonic/hypersonic aircrafts. © 2012 Elsevier Ltd.

Ismail M.,Cairo University | Adel A.,Cairo University | Adel A.,Majmaah University
Physical Review C - Nuclear Physics | Year: 2014

The influence of nuclear deformation on α-decay half-lives is taken into account in the deformed density-dependent cluster model. The microscopic potential between the spherical α particle and the deformed daughter nucleus is evaluated numerically from the double-folding model by the multipole expansion method. A realistic density-dependent nucleon-nucleon (NN) interaction with finite-range exchange part, which produces the nuclear matter saturation curve and the energy dependence of the nucleon-nucleus optical potential model is used. The ordinary zero-range exchange NN force, which is commonly used in α decay, is also considered in the present work. We systematically investigate the influence of nuclear deformations on the α-particle preformation probability of the deformed medium and heavy nuclei from the ground state to ground-state α transitions within the framework of the Wentzel-Kramers-Brillouin method by considering the Bohr-Sommerfeld quantization condition. Taking the deformation of daughter nuclei into account changes the behavior of the preformation probability, Sα, by an amount depending on the Q value, the order, values, and signs of deformation parameters. Calculations have been conducted for the spherical nuclei in order to present clearly the effect of the deformation on the preformation probability. The combined effect of both finite-range force and deformation can reduce the value of Sα by about an order of magnitude. © 2014 American Physical Society.

Khabaz A.,Majmaah University
Construction and Building Materials | Year: 2016

The efficiency of hardened composite of Steel Fiber Reinforced Concrete (SFRC) is mainly related to the ability of its components to work together homogeneously. This homogeneously work of SFRC components might be obtained through sufficient bond between the fiber and the concrete matrix at its contact points on the interface surfaces. Usually, if a smooth and straight steel fiber is embedded in concrete matrix and subjected to tensile force, only weak bond may obtain at the interface between the fiber and the concrete. This weak bond decreases gradually parallel with increasing the value of the applied tensile force in the pull-out test, and the fiber can't develop its yield strength, whereas debond length increases toward the depth of the concrete along the embedded length of the fiber until failure occurs in bond strength between the fiber and the concrete, then the fiber pulls out of the concrete through frictional sliding movement. The fracture mechanism of bond strength between the fiber and the concrete might be observed through pull-out tests. To enhance the bond strength performance of the fiber without change the concrete mix properties, it is necessary to find sophisticated form for the fiber such as end hooks. Monitoring of impact of hooked ends on mechanical behavior of steel fiber in concrete is observed during this research, where various pull-out experiments of single steel fiber in two forms (straight and hooked ends) are set using different values of embedded fiber length in concrete matrix. As well as computer simulations of single steel fiber with hooked ends embedded in concrete matrix are created using finite element model to monitor the development of stresses in different directions. Nonlinear results with contour maps and curves of different types of stresses are also obtained from the computer simulations, and numerical evaluation of the impact of enhancing the steel fiber shape has been done through this research. © 2016 Elsevier Ltd. All rights reserved.

Tlili I.,Majmaah University
Renewable and Sustainable Energy Reviews | Year: 2012

Maximum power and efficiency at the maximum power point of an endoreversible Stirling heat engine with finite heat capacitance rate of external fluids in the heat source/sink reservoirs with regenerative losses are treated. It was found that the thermal efficiency depends on the regenerator effectiveness and the internal irreversibility resulting from the working fluid for a given value of reservoir temperature. It was also concluded that it is desirable to have larger heat capacity of the heat sink in comparison to the heat source reservoir for higher maximum power output and lower heat input. © 2012 Elsevier Ltd. All rights reserved.

The present exploration discusses the influence of Newtonian heating on the magnetohydrodynamic (MHD) three dimensional couple stress nanofluid past a stretching surface. Viscous dissipation and Joule heating effects are also considered. Moreover, the nanofluid model includes the combined effects of thermophoresis and Brownian motion. Using an appropriate transformation, the governing non linear partial differential equations are converted into nonlinear ordinary differential equations. Series solutions using Homotopy Analysis method (HAM) are computed. Plots are presented to portrait the arising parameters in the problem. It is seen that an increase in conjugate heating parameter results in considerable increase in the temperature profile of the stretching wall. Skin friction coefficient, local Nusselt and local Sherwood numbers tabulated and analyzed. Higher values of conjugate parameter, Thermophoresis parameter and Brownian motion parameter result in enhancement of temperature distribution. © 2015 Muhammad Ramzan.

Alklaibi A.M.,Majmaah University
Energy Conversion and Management | Year: 2015

The internal two-stage evaporative cooler is studied by experimentally comparing its performance with direct evaporative cooler and theoretically with direct and external two-stage evaporative coolers. The results show that the efficiency of the internal two-stage evaporative cooler is higher than that of direct evaporative cooler but it cannot be raised over 100%. It was also shown that the efficiency of the internal evaporative cooler type is less sensitive to air speed than direct type. The efficiency of the direct evaporative cooler increases by 12%, and the internal evaporative cooler increases only by 5% when fan speed switches from high to low value. The results also show that the supply air of the internal evaporative cooler has higher humidity content than direct evaporative cooler which makes it a good humidifier in cold storages where humidly close to saturation is required. © 2015 Elsevier Ltd All rights reserved.

This paper proposes an artificial bee colony approach to minimize the makespan for a single batch-processing machine. The single batch-processing problem is characterized by discontinuity in the objective function and having integer variables. Since the problem under study is NP-hard, an artificial bee colony approach is proposed. The penalty function method is used to convert the constrained problem to unconstrained problem, which is then solved by the ABC algorithm. A procedure to generate initial solutions is presented, which is based on filling partially filled batches first. The analysis in the article shows that the colony size, the value of the penalty parameter, the penalty function iteration, the ABC iteration, and maximum trials per food source all have a significant effect on the performance of the ABC algorithm; however, no pattern can be established. © 2015 Elsevier B.V. All rights reserved.

This article develops an economic production quantity (EPQ) model for the case where the production process and inspection are both not perfect. Unlike the models in the literature, the proposed model aims to find the optimal lot size for a manufacturer who produces items in batches; and the batches are subjected to destructive or non-destructive acceptance sampling process before batches can be sent out to the market. The manufacturer can use destructive testing or non-destructive testing that can best assess the primary quality characteristic. Two errors can happen in this stage: Type 1 and Type 2 errors. If a lot is rejected, it goes through a more expensive non-destructive screening stage to segregate items into nondefective, reworkable, and salvage. Items that reach the primary market and found to be defective are returned, with a return cost to the manufacturer; in this case, returned items are either reworked or sold as salvage. The expected net profit function consists of the following components: primary and secondary market sales, sales of salvage items, setup and variable production cost, return cost, rework cost, screening cost, destructive cost, work-in-process, sales items inventory, rework item inventory, and salvage inventory. For both destructive and non-destructive testing situations, the optimal lot size has been found and the optimality criterion has been tested. The article concludes with a numerical example and sensitivity analysis. © 2015 Elsevier Ltd. All rights reserved.

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