Babol Noshirvani University of Technology
Babol, Iran

Babol Noshirvani University of Technology is a technical university in Babol, a city in Mazandaran Province in the north of Iran, 20 km south of the Caspian Sea. Wikipedia.

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Malvandi A.,Islamic Azad University at Karaj | Ganji D.D.,Babol Noshirvani University of Technology
International Journal of Thermal Sciences | Year: 2014

The current study is a theoretical investigation of the laminar flow and convective heat transfer of alumina/water nanofluid inside a circular microchannel in the presence of a uniform magnetic field. A modified two-component four-equation nonhomogeneous equilibrium model was employed for nanofluids, which fully accounted for the effect of the nanoparticle volume fraction distribution. Because of the microscopic roughness in circular microchannels and also the non-adherence of the fluid-solid interface in the presence of nanoparticle migration, known as slip condition, the Navier's slip boundary condition is considered at the walls. The results indicated that nanoparticles migrate from the heated walls (nanoparticles depletion) towards the core region of the microchannel (nanoparticles accumulation) and construct a non-uniform nanoparticles distribution. The ratio of the Brownian to thermophoretic diffusivities (NBT) has relatively significant effects both on the distribution of the nanoparticles and the convective heat transfer coefficient of nanofluids. It was further observed that for smaller nanoparticles, the nanoparticle volume fraction is more uniform and abnormal variations in the heat transfer rate vanish. Moreover, in the presence of the magnetic field, the near wall velocity gradients increase, enhancing the slip velocity and thus the heat transfer rate and pressure drop increase. © 2014 Elsevier Inc. All rights reserved.

Sakhaei S.M.,Babol Noshirvani University of Technology
Ultrasonics | Year: 2015

Minimum variance beamforming has performed significant improvement in the resolution of the ultrasound images. However, its computational complexity is a serious problem. This paper introduces a new implementation of the minimum variance beamformer for ultrasound imaging with a focused transmit beam. In this method, a decimated aperture data instead of full of it, is used as the beamformer input, on which the minimum variance beamforming is applied, with the covariance matrix estimated using the full aperture data. In this way, the method can give a linear complexity while it can show a performance comparable to that of the full array implementation of the minimum variance beamforming, as the simulation and experimental results confirm this. Therefore, this adaptive beamforming method can be viewed as an approximate implementation of the minimum variance beamforming with a linear computational complexity. © 2015 Elsevier B.V. All rights reserved.

Rahimpour A.,Babol Noshirvani University of Technology
Desalination | Year: 2011

Polyethersulfone (PES) membrane was prepared via immersion precipitation technique and modified by UV photo-grafting of hydrophilic monomers on the top surface of the membrane. Acrylic acid (AA) and 2-hydroxyethylmethacrylate (HEMA) as acrylic monomers and 1,3-phenylenediamine (mPDA) and ethylene diamine (EDA) as amino monomers were used at different concentrations to improve the surface properties of the membrane. The unmodified and modified PES membranes were characterized by contact angle, ATR-FTIR, scanning electron microscopy (SEM), atomic force microscopy (AFM), cross flow filtration and fouling analysis. The contact angle measurements indicated that the hydrophilicities of the membranes were significantly increased by UV photo-grafting of hydrophilic monomers onto the membrane surface. The ATR-FTIR spectra, SEM and AFM images confirmed that the modification on the PES membrane surface was carried out by UV photo-grafting of hydrophilic monomers. The solute transport data showed that the surface mean pore size of the unmodified membrane declined from 15.8. nm to 6.1, 3.9, 5.5 and 5.7. nm for 6. wt.% of AA, HEMA, mPDA and 5. wt.% of the EDA modified membranes, respectively. The pure water flux and milk water permeation of the membranes were declined by UV photo-grafting but the protein rejection was improved. Moreover, the antifouling properties and flux recovery of the PES membrane were modified by UV photo-grafting of hydrophilic monomers. © 2010 Elsevier B.V.

Sheikholeslami M.,Babol Noshirvani University of Technology | Ganji D.D.,Babol Noshirvani University of Technology
Powder Technology | Year: 2013

Heat transfer of a nanofluid flow which is squeezed between parallel plates is investigated analytically using homotopy perturbation method (HPM). Copper as nanoparticle with water as its base fluid has been considered. The effective thermal conductivity and viscosity of nanofluid are calculated by the Maxwell-Garnetts (MG) and Brinkman models, respectively. This investigation is compared with other numerical methods and they were found to be in excellent agreement. The effects of the squeeze number, the nanofluid volume fraction and Eckert number and δ on Nusselt number are investigated. The results show that Nusselt number has direct relationship with nanoparticle volume fraction, δ, the squeeze number and Eckert number when two plates are separated but it has reverse relationship with the squeeze number when two plates are squeezed. © 2012 Elsevier B.V.

Ganji D.D.,Babol Noshirvani University of Technology
Journal of Hydro-Environment Research | Year: 2012

Reliable knowledge of a free falling solid particle in a quiescent liquid is necessary for a range of chemical, mineral and process engineering applications. A recent series-integral-based mathematical method, called the variational iteration method, is used, and a semi-exact solution is derived for the instantaneous velocity of the particle versus time. The equation is solved for its general form and for a realistic combination of solid-liquid systems, and the convergence of the methods is examined for a special case. The results obtained are compared with previous analytical results and the finite difference method. The outcomes clearly demonstrate the falling behavior of a particle settling in an incompressible fluid and show the effectiveness and simplicity of the current mathematical method. © 2012 International Association for Hydro-environment Engineering and Research, Asia Pacific Division.

Sheikholeslami M.,Babol Noshirvani University of Technology | Ganji D.D.,Babol Noshirvani University of Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2015

The problem of nanofluid hydrothermal behavior in presence of variable magnetic field is investigated analytically using Differential Transformation Method. The fluid in the enclosure is water containing different types of nanoparticles: Al2O3 and CuO. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL (Koo-Kleinstreuer-Li) correlation. In this model effect of Brownian motion on the effective thermal conductivity is considered. The comparison between the results from Differential Transformation Method and previous work are in well agreement which proved the capability of this method for solving such problems. The effect of the squeeze number, nanofluid volume fraction, Hartmann number and heat source parameter on flow and heat transfer is investigated. The results show that skin friction coefficient increases with increase of the squeeze number and Hartmann number but it decreases with increase of nanofluid volume fraction. Nusselt number increases with augment of nanoparticle volume fraction, Hartmann number while it decreases with increase of the squeeze number. © 2014 Elsevier B.V.

Kandelousi M.S.,Babol Noshirvani University of Technology
European Physical Journal Plus | Year: 2014

Ferrofluid flow and heat transfer in the presence of an external variable magnetic field is studied. The inner cylinder is maintained at uniform heat flux and the outer cylinder has constant temperature. The Control Volume based Finite Element Method (CVFEM) is applied to solve the governing equations. Combined magnetohydrodynamic and ferrohydrodynamic effects have been taken into account. The effects of magnetic number, Hartmann number, Rayleigh number and nanoparticle volume fraction on hydrothermal behavior have been examined. Results show that the Nusselt number is an increasing function of Magnetic number, Rayleigh number and nanoparticle volume fraction while it is a decreasing function of the Hartmann number. Also, it can be concluded that the enhancement in heat transfer decreases with an increase in the Rayleigh number and magnetic number but it increases with an increase in the Hartmann number. © 2014, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg.

Sheikholeslami Kandelousi M.,Babol Noshirvani University of Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

Hydrothermal behavior of nanofluid fluid between two parallel plates is studied. One of the plates is externally heated, and the other plate, through which coolant fluid is injected, expands or contracts with time. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL correlation. The effects of the nanoparticle volume fraction, Reynolds number, Expansion ratio and power law index on Hydrothermal behavior are investigated. Results show that heat transfer enhancement has direct relationship with Reynolds number when power law index is equals to zero but opposite trend is observed for other values of power law index. © 2014 Elsevier B.V. All rights reserved.

Modarres A.,Babol Noshirvani University of Technology
Construction and Building Materials | Year: 2013

Temperature susceptibility is one of the main inherent properties of asphalt binders. Nowadays, polymer materials are extensively utilized to extend the range of service temperature which finally will confine the temperature induced damages in asphalt mixes. The main goal of this research was to investigate the effect of temperature on the toughness index and fatigue properties of SBS modified asphalt mixes. Utilizing a UTM apparatus which equipped with a temperature control chamber, the indirect tensile strength and indirect tensile fatigue tests were carried out at three testing temperatures of -10, 20 and 50 C. Based on obtained results at lower temperatures toughness index considerably reduced which indicated the lower flexibility of studied mixes. However, toughness index of modified mixes was to some extent higher than that of conventional mixes. Obtained results confirmed that at high loading conditions, fatigue failure will be more critical at low to moderate temperatures. In contrast, at lower loading conditions in which the strain values are less than about 200-250 microstrain the fatigue failure is not critical at low temperatures. © 2013 Elsevier Ltd. All rights reserved.

Sherme A.E.,Babol Noshirvani University of Technology
Applied Soft Computing Journal | Year: 2012

Automatic recognition of the digital modulation plays an important role in various applications. This paper investigates the design of an accurate system for recognition of digital modulations. First, it is introduced an efficient pattern recognition system that includes two main modules: the feature extraction module and the classifier module. Feature extraction module extracts a suitable combination of the higher order moments up to eighth, higher order cumulants up to eighth and instantaneous characteristics of digital modulations. These combinations of the features are applied for the first time in this area. In the classifier module, two important classes of supervised classifiers, i.e., multi-layer perceptron (MLP) neural network and hierarchical multi-class support vector machine based classifier are investigated. By experimental study, we choose the best classifier for recognition of the considered modulations. Then, we propose a hybrid heuristic recognition system that an optimization module is added to improve the generalization performance of the classifier. In this module we have used a new optimization algorithm called Bees Algorithm. This module optimizes the classifier design by searching for the best value of the parameters that tune its discriminant function, and upstream by looking for the best subset of features that feed the classifier. Simulation results show that the proposed hybrid intelligent technique has very high recognition accuracy even at low levels of SNR with a little number of the features. © 2011 Elsevier B.V. All rights reserved.

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