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    Explicit renormalization group for D=2 random bond ising model with long-range correlated disorder

    , Article Journal of Statistical Physics ; Volume 130, Issue 4 , 2008 , Pages 815-820 ; 00224715 (ISSN) Rajabpour, M. A ; Sepehrinia, R ; Sharif University of Technology
    2008
    Abstract
    We investigate the explicit renormalization group for fermionic field theoretic representation of two-dimensional random bond Ising model with long-range correlated disorder. We show that a new fixed point appears by introducing a long-range correlated disorder. Such as the one has been observed in previous works for the bosonic (φ 4) description. We have calculated the correlation length exponent and the anomalous scaling dimension of fermionic fields at this fixed point. Our results are in agreement with the extended Harris criterion derived by Weinrib and Halperin. © 2007 Springer Science+Business Media, LLC  

    Perturbed logarithmic CFT and integrable models

    , Article Nuclear Physics B ; Volume 754, Issue 3 , 2006 , Pages 283-292 ; 05503213 (ISSN) Rajabpour, M. A ; Rouhani, S ; Sharif University of Technology
    2006
    Abstract
    Perturbation of logarithmic conformal field theories using Zamolodchikov's method is investigated. We derive conditions for the perturbing operator, such that the perturbed model be integrable. We also consider an example where an integrable model arises out of perturbation of the c = - 2 logarithmic conformal field theory. © 2006 Elsevier B.V. All rights reserved  

    Numerical Study of Anisotropic Wetting of Nano-Droplets on Chemically Patterned Surfaces

    , M.Sc. Thesis Sharif University of Technology Rajabpour, Shahram (Author) ; Moosavi, Ali (Supervisor)
    Abstract
    This study investigates three-dimensional modeling of nanodroplets over chemically patterned surfaces. The pattern can be established by changing the contact angle on the surface. The problem is studied numerically by solving the thin film equations.Both the long-range and short-range inter-molecular interactions are considered. The numerical procedure is validated by using the theoretical studies. The effects of parameters such as the size of the droplets, the gradient of the surface, and the slip coefficient on the dynamics and speed of droplets and the shape of them during the motion are inspected.By examining the dynamics of the system it is revealed that the velocity of the droplets... 

    Cathodic Protection of Underground Pipeline by Polyurethane Coating

    , M.Sc. Thesis Sharif University of Technology Rajabpour, Foroud (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Selection of appropriate coating system is the most important subject in corrosion control of buried pipelines. Corrosion control of buried pipelines is achieved by using a combination of barrier coatings and cathodic protection (CP). Applying barrier coating can decrease the protection current of CP. However, at the coating holidays the pipeline act as cathode generating hydroxyl ion and hydrogen electrochemically. Therefore the selected coating should be compatible with the alkaline condition.This research focuses on evaluating of an epoxy-tar and a urethane-tar based coating. Coatings performance has been tested by accelerated corrosion test methods (i.e. Salt spray according to ASTM... 

    Molecular dynamics investigation of β-SiC behavior under three-axial tensile loading [electronic resource]

    , Article Journal of Computational and Theoretical Nanoscience ; November 2011, Volume 8, Number 11, PP. 2187-2192 Mortazavi, B ; Simchi, A. (Abdolreza) ; Besharati-Givi, M.K ; Rajabpour, A ; Sharif University of Technology
    Abstract
    Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress–strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress–strain relationship. The MD... 

    Mechanical behaviors of titanium nitride and carbide MXenes: A molecular dynamics study

    , Article Applied Surface Science ; Volume 566 , 2021 ; 01694332 (ISSN) Hatam Lee, S. M ; Esfandiar, A ; Rajabpour, A ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    MXenes have recently witnessed significant evolution and advances in terms of their applications in different areas such as flexible electronics, energy storage devices, and coatings. Here, the mechanical properties of both pristine and functionalized Tin+1CnO2 and Tin+1NnO2 (n = 1, 2) are investigated utilizing classical molecular dynamics simulations. For eight different MXene structures, the stress-strain curves are calculated including Young's modulus, strength, and fracture strain. It is found that Ti2N holds the highest Young's modulus with the value of 517 GPa while Ti3C2 has the lowest one with the amount of 133 GPa. In addition, the strongest MXene structure is Ti2N while the... 

    Some aspects of c = -2 theory

    , Article Fortschritte der Physik ; Volume 55, Issue 11-12 , 2007 , Pages 1289-1308 ; 00158208 (ISSN) Rajabpour, M. A ; Rouhani, S ; Saberi, A. A ; Sharif University of Technology
    2007
    Abstract
    We investigate some aspects of the c = -2 logarithmic conformal field theory (LCFT). At first, we calculate some correlators of logarithmic conformal fields which have third order singular OPE with the energymomentum tensor. Then, we argue about the fields in the c = -2 model which are associated with this kind of more general logarithmic primary fields. We go on to find fermionic representations for all the fields in the extended Kac table, in particular the untwisted sector. Moreover, we calculate the various OPEs of the fields, especially for the logarithmic energy-momentum tensor and by using these OPEs we find the exact finite transformation of this field. We briefly discuss about the... 

    Theoretical and experimental investigation of design parameter effects on the slip phenomenon and performance of a centrifugal compressor

    , Article Scientia Iranica ; Volume 28, Issue 1 , 2021 , Pages 291-304 ; 10263098 (ISSN) Rajabpour, S ; Hajilouy Benisi, A ; Manzari, M. T ; Sharif University of Technology
    Sharif University of Technology  2021
    Abstract
    Numerous studies have investigated driving equations used to predict the slip factor in centrifugal compressors so far. Inevitably, through these studies, the ow field characteristics have been simplified and the effects of the related parameters have been neglected. The present study, experimentally and numerically, investigates the slip phenomenon in a specific centrifugal compressor with complex blade curves and splitter blades, considering the main effective parameters such as the number of blades, exit angle, etc. To this end, a three-dimensional simulation of the viscous flow field of the compressor via an appropriate turbulence method was performed. In addition, an experimental study... 

    Molecular dynamics investigation of β-SiC behavior under three-axial tensile loading

    , Article Journal of Computational and Theoretical Nanoscience ; Volume 8, Issue 11 , 2011 , Pages 2187-2192 ; 15461955 (ISSN) Mortazavi, B ; Simchi, A ; Besharati Givi, M. K ; Rajabpour, A ; Sharif University of Technology
    2011
    Abstract
    Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress- strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress-strain relationship. The MD... 

    Enhanced local viscosity around colloidal nanoparticles probed by equilibrium molecular dynamics simulations

    , Article Journal of Chemical Physics ; Volume 155, Issue 17 , 2021 ; 00219606 (ISSN) Rabani, R ; Saidi, M. H ; Joly, L ; Merabia, S ; Rajabpour, A ; Sharif University of Technology
    American Institute of Physics Inc  2021
    Abstract
    Nanofluids - dispersions of nanometer-sized particles in a liquid medium - have been proposed for a wide variety of thermal management applications. It is known that a solid-like nanolayer of liquid of typical thicknesses of 0.5-1 nm surrounding the colloidal nanoparticles can act as a thermal bridge between the nanoparticle and the bulk liquid. Yet, its effect on the nanofluid viscosity has not been elucidated so far. In this article, we compute the local viscosity of the nanolayer using equilibrium molecular dynamics based on the Green-Kubo formula. We first assess the validity of the method to predict the viscosity locally. We apply this methodology to the calculation of the local... 

    Enhanced Heat Flow between Charged Nanoparticles and an Aqueous Electrolyte

    , Article Langmuir ; Volume 39, Issue 43 , 2023 , Pages 15222-15230 ; 07437463 (ISSN) Rabani, R ; Saidi, M. H ; Rajabpour, A ; Joly, L ; Merabia, S ; Sharif University of Technology
    American Chemical Society  2023
    Abstract
    Heat transfer through the interface between a metallic nanoparticle and an electrolyte solution has great importance in a number of applications, ranging from nanoparticle-based cancer treatments to nanofluids and solar energy conversion devices. However, the impact of the surface charge and dissolved ions on heat transfer has been scarcely explored so far. In this study, we compute the interface thermal conductance between hydrophilic and hydrophobic charged gold nanoparticles immersed in an electrolyte using equilibrium molecular dynamics simulations. Compared with an uncharged nanoparticle, we report a 3-fold increase of the Kapitza conductance for a nanoparticle surface charge of +320... 

    Experimental evaluation on the effect of biomechanical features on human body stiffness

    , Article Proceedings of the International Congress on Sound and Vibration ; 2023 ; 23293675 (ISSN); 978-801103423-8 (ISBN) Hejazi dinan, P ; Aziminia, M ; Emamian, A ; Shamsipour Dehkordi, P ; Rajabpour Sani, Z ; Carletti E ; Sharif University of Technology
    Society of Acoustics  2023
    Abstract
    Human body stiffness plays an important role in whole body vibration analysis and also athletic performance and motor control. In recent years researchers focused on calculating lower-extremity stiffness for better monitoring vibration of whole body and also improving athletic performance and decreasing their injuries. Lower limb power, stiffness and muscular strength are often obtained from maximal vertical jump which is an important motor skill in physical activities. The stiffness can be calculated by vertical reaction force divided by vertical movement of mass centre. During running and jumping, legs can be modelled as a spring with the body mass sitting at the top. With regard to the...