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Shokravi M.,Buein Zahra Technical University
Computers and Concrete | Year: 2017

In this paper, nonlinear vibration of embedded nanocomposite concrete is investigated based on Timoshenko beam model. The beam is reinforced by with agglomerated silicon dioxide (SiO2) nanoparticles. Mori-Tanaka model is used for considering agglomeration effects and calculating the equivalent characteristics of the structure. The surrounding foundation is simulated with Pasternak medium. Energy method and Hamilton's principal are used for deriving the motion equations. Differential quadrature method (DQM) is applied in order to obtain the frequency of structure. The effects of different parameters such as volume percent of SiO2 nanoparticles, nanoparticles agglomeration, elastic medium, boundary conditions and geometrical parameters of beam are shown on the frequency of system. Numerical results indicate that with increasing the SiO2 nanoparticles, the frequency of structure increases. In addition, considering agglomeration effects leads to decrease in frequency of system. © 2017 Techno-Press, Ltd.

In the present research, dynamic pull-in and pull-out analysis of viscoelastic nanoplate switch under electrostatic and intermolecular Casimir forces are studied. The Viscoelastic properties of the nanoplate are considered using Kelvin-Voigt model. Sinusoidal shear deformation theory is utilized for mathematical modeling of the structure due to its accuracy of polynomial function than other plate theories. The surface effects are considered based on Gurtin-Murdoch theory to enhance the accuracy of results. Considering size effects based on Eringen's nonlocal theory, motion equations are derived using Hamilton's principle and solved by Galerkin's method. Considering two boundary conditions of clamped in all edges (CCCC) and clamped in two edges and free in tow another edges (CCFF), the influences of various parameters such as small scale effect, surface layer, viscoelastic damping coefficient and applied voltage on the pull-in voltage, pull-in time, pull-in deflection and pull-out voltage are discussed in details. Numerical results indicate that considering small scale effects, the pull-in time and voltage as well as pull-out voltage are increased and decreased, respectively, for CCFF and CCCC boundary conditions. In addition, as the effective gap distance increases, the pull-out voltage tends toward the pull-out voltage. The results of this investigation can be used in control and optimum design of smart nano-electrical devices in advanced applications as smart controller. © 2017 Elsevier Ltd

Ghandvar H.,University of Technology Malaysia | Farahany S.,Buein Zahra Technical University | Idris M.H.,University of Technology Malaysia
Tribology Transactions | Year: 2017

In this study, the effect of wettability improvement of SiCp on the impact and sliding wear behavior of A356/20 wt% SiCp composites produced by a compocasting technique has been investigated. The result showed an increase of incorporation and uniform distribution of SiCp in the A356 matrix by elimination of SiCp segregation. Desired bonding between SiCp and the aluminum matrix due to improved wettability resulted in enhanced properties in terms of improved impact toughness and wear resistance. This improvement was also associated with partial refinement of coarse eutectic silicon due to increased incorporation and distribution of SiCp reinforcements. The highest enhancement was obtained when 1% Mg was added into the melt in addition to pretreated SiCp. The impact toughness value increased by 10 and 26% and the wear rate decreased by 5 and 30% when the SiC was treated and when Mg was added, respectively, compared to as-received SiCp. The impact fracture surfaces showed fewer decohered and well-bonded SiC particles in A356–(SiC-treated-Mg) composite. The highest wear resistance of A356/SiCp composites was achieved by A356–(SiC-treated-Mg) composite for applied loads of 10 and 20 N compared to other fabricated composites. The worn surface revealed mild abrasion and adhesion wear mechanisms. © 2017 Society of Tribologists and Lubrication Engineers

Ghashochi-Bargh H.,Buein Zahra Technical University | Razavi S.,Islamic Azad University at Tabriz
Alexandria Engineering Journal | Year: 2017

With the widespread application of composite structures in engineering, the static and dynamic analyses of these structures have become important in the past years. Composite and functionally graded plates have been frequently being used and are important parts of many engineering structures. Numerous plate theories and solution procedures have been presented to predict the linear dynamic response of composite and functionally graded plates. This study aims to develop a simple analytical model to predict the free vibration response of orthotropic and functionally graded rectangular plates with clamped and simply-supported boundary conditions. To this end, Mindlin's shear deformation plate theory has been used to obtain the equations of motion in terms of transverse displacement and rotations of mid-plane of the plate. After expressing the rotation parameters in terms of the transverse displacement, they have been substituted into equation of transverse motion of the plate. Then, for each boundary condition, an appropriate function has been assumed for the transverse displacement of the plate. Using the orthogonality of these functions, the natural frequencies of the plate have been determined. Some examples have been provided to validate the proposed model. © 2017 Faculty of Engineering, Alexandria University.

Seifbarghy M.,Islamic Azad University at Qazvin | Nouhi K.,Islamic Azad University at Qazvin | Mahmoudi A.,Buein Zahra Technical University
International Journal of Production Economics | Year: 2015

We consider a two-level supply chain consisting of a manufacturer and a retailer. The retailer gives a final product to a competitive market with customer sensitive to price. The customer demand is assumed to be constant depending on the price and quality degree of the final product. The manufacturer decides on the quality degree of the product. The optimal values of the major decision variables of the chain are determined for different conditions. The supply chain in centralized condition is considered and the optimal values of the price and the quality degree are found. Chain profit in decentralized condition is optimized and the optimal values of wholesale price and quality degree are determined. Retailers revenue sharing contract is designed and the optimal values of wholesale price and quality degree are found. Finally, a market segmentation condition in which customers are divided into two categories of quality oriented and price oriented is considered; then, the threshold of the percentage of potential quality oriented customers is determined. A set of numerical examples are designed in order to analyze the optimal values of the decision variables. © 2015 Elsevier B.V. All rights reserved.

Taheri S.M.-R.,Institute for Advanced Studies in Basic Sciences | Madadi E.,Buein Zahra Technical University | Sadeghi M.,Institute for Advanced Studies in Basic Sciences | Reihani S.N.S.,Sharif University of Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2015

Optical tweezers have proven to be indispensable micromanipulation tools especially in aqueous solutions. Because of the significantly larger spherical aberration induced by the refractive index mismatch, trapping aerosols has always been cumbersome if not impossible. We introduce a simple but very efficient method for optimized aerosol trapping at a desired depth. We show that a wise selection of the immersion medium and the mechanical tube length not only enables trapping of objects that are known to be untrappable but also provides a way to tune the trappable depth range. © 2015 Optical Society of America.

Razavykia A.,University of Technology Malaysia | Farahany S.,Buein Zahra Technical University | Yusof N.M.,University of Technology Malaysia
Measurement: Journal of the International Measurement Confederation | Year: 2015

Al-Mg2Si particulate metal matrix composites (PMMC) has recently received wider attention because of its improved properties, however there is a lack of knowledge about machinability characteristics of these composites especially with bismuth addition. The purpose of this study is to evaluate the machining parameters and modifier element effects on cutting force (Fc) and surface roughness (Ra) when dry turning Al-Mg2Si with a coated carbide tool (K10U). The experimental trials are designed using the multi-level factorial design (DOE) and their results are analyzed using Analysis of Variance (ANOVA). Statistical models are developed to represent the relationship among machining parameters as independent variables, surface roughness and cutting force as response variables. For each experiment, a new cutting insert is used to encourage accurate reporting of the cutting force and surface roughness. The statistical observation revealed that the main effect of cutting speed, feed rate and modifier element influenced the cutting force and surface roughness. Moreover, there are no interaction effects of variables. Built-up-edge (BUE) formation was observed at every combinations of cutting speed and feed rate which affected the surface quality negatively. The proximity of predicted results and experimental results provide evidence that the DOE method has successfully derived the predictive models. The addition of Bi as modifier reagent results in lower cutting force and better surface roughness due to the formation of Bi compound and modifies the morphology of Mg2Si reinforcement particle. Our findings showed that the Bi is a promising element to improve the machinability of Al-Mg2Si composite. © 2015 Elsevier Ltd. All rights reserved.

Naji J.,Ilam University | Heshmatian S.,Buein Zahra Technical University
Canadian Journal of Physics | Year: 2016

We consider a charged rotating black hole in three dimensions with a scalar charge and discuss the jet-quenching parameter. We find that the effect of scalar charge and electric charge is to increase the jet-quenching parameter while the rotation of the black hole may decrease the value of the jet-quenching parameter. We find that viscosity of quark-gluon plasma is enhanced because of the electric and scalar charges. © 2016 Published by NRC Research Press.

Davoudi M.,Buein Zahra Technical University
21st Electrical Power Distribution Network Conference, EPDC 2016 | Year: 2016

This paper investigates the effects of Phasor Measurement Unit (PMU) on the correlation of Weighted Least Squares (WLS) power system state estimator's results. For this aim an approach is introduced to perform this analysis in real power grids considering the line parameters and measurement uncertainty. This approach is based on Monte Carlo simulations and is used to realize how much inclusion of PMU data in the measurements will affect the state estimator's correlation behavior whereas the network parameters are subjected to different quantities of uncertainties for a given measurement uncertainty. The approach is simulated on the IEEE 30-Bus test case and to illustrate the correlation of the state estimation results, the estimates correlations are computed versus different amounts of network line parameters uncertainty for one set of PMU locations. The novelty of this analysis lies behind the point that how PMUs will impact the estimates correlations in a realistic network with uncertain parameters. This analysis belongs to the extensive research on the effects of PMU on realistic power system state estimation that has initiated by the author in 2009. © 2016 IEEE.

Madadi E.,Buein Zahra Technical University
Journal of the Optical Society of America B: Optical Physics | Year: 2016

The special features of noble metals make them versatile and able to be used as handles in optical trapping. The trapping of various metal nanostructures has been investigated in the literature. In this paper, the optical trapping of hollow gold and silver nanoparticles is studied as a function of the trapping depth. It is shown that the trapping of hollow nanoparticles stiffens with the cavity size. It is shown that the trapping strength and the trapping efficiency enhance five-fold and two-fold, respectively. © 2016 Optical Society of America.

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