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ashraf--sajad
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Adversarial Attack to Deep Learning Networks via Imperceptible Sparse Perturbation
, M.Sc. Thesis Sharif University of Technology ; Ghaemmaghami, Shahrokh (Supervisor) ; Marvasti, Farokh (Supervisor) ; Amini, Sajad (Co-Supervisor)
Abstract
Nowadays, methods based on deep learning networks are the most effective artificial in telligence methods. Although they have achieved success in various fields (such as machine vision and object recognition), practical and experimental cases show the fragility of deep learning networks against perturbations and unwanted changes of the input pattern. All these perturbations must be in a way that the main class of the perturbed input pattern can be rec ognized by human, but the network makes a mistake in recognizing its correct class. This thesis seeks a more accurate evaluation by designing adversarial attacks such that the main class of the adversarial pattern is detectable by human...
Mhd flow of cu-al2o3/water hybrid nanofluid through a porous media
, Article Journal of Porous Media ; Volume 24, Issue 7 , 2021 , Pages 61-73 ; 1091028X (ISSN) ; Ali, K ; Ashraf, M ; Sharif University of Technology
Begell House Inc
2021
Abstract
Hybrid nanoliquids comprise of better physical strength, mechanical resistance, thermal conductivity, and chemical stability as equated to individual nanoliquids. In this paper, MHD hybrid nanoparticle flow with heat and mass transfer attributes is numerically investigated. Flow is taken over a stretching surface embedded in a porous medium. The governing flow model partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using a powerful tool of similarity transformations. The relevant system of differential equations and boundary conditions are numerically treated with the successive over-relaxation (SOR) technique. Heat and mass transfer features...
Mhd flow of cu-al2o3/water hybrid nanofluid through a porous media
, Article Journal of Porous Media ; Volume 24, Issue 7 , 2021 , Pages 61-73 ; 1091028X (ISSN) ; Ali, K ; Ashraf, M ; Sharif University of Technology
Begell House Inc
2021
Abstract
Hybrid nanoliquids comprise of better physical strength, mechanical resistance, thermal conductivity, and chemical stability as equated to individual nanoliquids. In this paper, MHD hybrid nanoparticle flow with heat and mass transfer attributes is numerically investigated. Flow is taken over a stretching surface embedded in a porous medium. The governing flow model partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using a powerful tool of similarity transformations. The relevant system of differential equations and boundary conditions are numerically treated with the successive over-relaxation (SOR) technique. Heat and mass transfer features...
Casson fluid flow with heat and mass transfer in a channel using the differential transform method
, Article Kuwait Journal of Science ; Volume 49, Issue 1 , 2022 , Pages 1-19 ; 23074108 (ISSN) ; Ali, K ; Ashraf, M ; Sharif University of Technology
University of Kuwait
2022
Abstract
In the present investigation, we consider the heat and mass transfer characteristics of steady, incompressible and electrically conducting Casson fluid flow in a channel. The effect of chemical reactions have also been considered. The differential transform method (DTM) is applied to a system of non-linear ODEs, and the results are obtained in the form of DTM series. The principal gain of this approach is that it applies to the non-linear ODEs without requiring any discretization, linearization or perturbation. The velocity, mass and heat transfer profiles thus obtained are in good agreement with those provided by the quasi-linearization method (QLM). Graphical results for velocity,...
Investigating deep neural network architecture and feature extraction designs for sensor-based human activity recognition
, Article 7th International Conference on Internet of Things and Applications, IoT 2023 ; 2023 ; 979-835036941-0 (ISBN) ; Shirazi, M ; Ashraf, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
The extensive ubiquitous availability of sensors in smart devices and the Internet of Things (IoT) has opened up the possibilities for implementing sensor-based activity recognition. As opposed to traditional sensor time-series processing and hand-engineered feature extraction, in light of deep learning's proven effectiveness across various domains, numerous deep methods have been explored to tackle the challenges in activity recognition, outperforming the traditional signal processing and traditional machine learning approaches. In this work, by performing extensive experimental studies on two human activity recognition datasets, we investigate the performance of common deep learning and...
A Monte Carlo Method for Neutron Noise Calculation in the Frequency Domain
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
Neutron noise equations, which are obtained by assuming small perturbations of macroscopic cross sections around a steady-state neutron field and by subsequently taking the Fourier transform in the frequency domain, have been usually solved by analytical techniques or by resorting to diffusion theory, but in this thesis, in order to increase of accuracy of neutron noise calculation, has been used transport approximation for neutron noise calculation and the Monte Carlo method has been used to solve transport equation of the neutron noise in the frequency domain. Since the transport equation of the neutron noise is a complex equation, a new Monte Carlo technique for treating complex-valued...
Gamma irradiated electro-conductive polylactic acid/polyaniline nanofibers
, Article Synthetic Metals ; Volume 259 , 2020 ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, polyaniline nanoparticles (PANI NPs) in emeraldine base (EB) form were prepared by a modified method and characterized by FTIR and UV–vis spectroscopies. The average size of the nanoparticles was 140 nm measured by DLS method. The nanoparticles were embedded into polylactic acid (PLA) nanofibers prepared by electrospinning method. It was found that inclusion of PANI NPs in PLA resulted in reduced diameter of the fibers during the electrospinning process. Also, the surface of nanofibers appeared smooth in FE-SEM images without formation of beads. Improvement in mechanical and electrical properties of PLA/PANI nanofibers over the neat PLA nanofibers implied a good dispersion of...
Heat and mass transfer attributes of copper-aluminum oxide hybrid nanoparticles flow through a porous medium
, Article Case Studies in Thermal Engineering ; Volume 25 , 2021 ; 2214157X (ISSN) ; Ali, K ; Rizwan, M ; Ashraf, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Hybrid nanofluids possess better mechanical resistance, physical strength, chemical stability, thermal conductivity and so forth as compared to individual nanoliquids. Our approach in the present work is to offer a novel study involving MHD flow of hybrid nanoparticles with viscous dissipation effect through a porous medium past a stretching surface. A powerful tool of similarity transformation is utilized to transmute the governing flow model PDEs into ordinary ones. The entire system of nonlinear coupled differential equations along with boundary conditions is tackled numerically by means of Successive over Relaxation (SOR) technique. Two distinctive fluids, named Al2O3-Cu/water (hybrid...
Heat and mass transfer attributes of copper-aluminum oxide hybrid nanoparticles flow through a porous medium
, Article Case Studies in Thermal Engineering ; Volume 25 , 2021 ; 2214157X (ISSN) ; Ali, K ; Rizwan, M ; Ashraf, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Hybrid nanofluids possess better mechanical resistance, physical strength, chemical stability, thermal conductivity and so forth as compared to individual nanoliquids. Our approach in the present work is to offer a novel study involving MHD flow of hybrid nanoparticles with viscous dissipation effect through a porous medium past a stretching surface. A powerful tool of similarity transformation is utilized to transmute the governing flow model PDEs into ordinary ones. The entire system of nonlinear coupled differential equations along with boundary conditions is tackled numerically by means of Successive over Relaxation (SOR) technique. Two distinctive fluids, named Al2O3-Cu/water (hybrid...
A Lyapunov Functional for a Predator-Prey Model with Nonlinear Predation Rate and Periodic Solutions
, M.Sc. Thesis Sharif University of Technology ; Hesaraki, Mahmoud (Supervisor)
Abstract
In this thesis we consider the dynamics of a general predator-prey model which generalizes several known predator-prey, assuming that the intrinsic growth rate of the pray, the predation rate, and the removal functions are given in an unspecified form. Using the Lyapunov method, we derive sufficient conditions for the stability of the equilibria. also, we consider a delayed periodic predator- prey model and sufficient conditions are derived for the existence, uniqueness and global asymptotic stability of positive periodic solutions of the model.
Electrically Conductive Fibers and Films Based on PLA and Nano PANI
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Nowadays, the use of processed conductive polymers for conducting matrix polymers, as well as improving other properties for planting in the body, is very common. In this project, the fabrication and identification of electrically conductive films and fibers from biocompatible poly lactic acid and conductive polyAniline polymer in the form of nano-fibers or nanoparticles was intended. These fibers and films have been made in form of a plate or tube then, have been used as biosensors. These polymeric prostheses should be sterilized before planting in human body. Gamma rays are the best sterilization methods and are used at low doses (25 kGy) to sterilize plastic medical supplies. On the other...
Novel thermal aspects of hybrid nanoparticles Cu-TiO2 in the flow of ethylene glycol
, Article International Communications in Heat and Mass Transfer ; Volume 129 , 2021 ; 07351933 (ISSN) ; Ali, K ; Faridi, A. A ; Ashraf, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Hybrid nanoparticles possess better chemical stability, mechanical resistance, thermal conductivity, physical strength and so forth as equated to pure nanoparticles. The present work describes the novel features of hybrid nanoparticles such as Titanium oxide (TiO2) and Copper (Cu) in the flow of Ethylene glycol (EG) under the induced magnetic field environment. The analysis covers the features of both pure nanofluid Cu/EG and hybrid nanofluid Cu-TiO2/EG. The concentration equation is amended by the activation energy term. The amalgamation of Cu-TiO2/EG exhibits improved and embellished thermal characteristics. A persuasive numerical technique named “Successive over Relaxation” is used to...
Novel thermal aspects of hybrid nanoparticles Cu-TiO2 in the flow of ethylene glycol
, Article International Communications in Heat and Mass Transfer ; Volume 129 , 2021 ; 07351933 (ISSN) ; Ali, K ; Faridi, A. A ; Ashraf, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Hybrid nanoparticles possess better chemical stability, mechanical resistance, thermal conductivity, physical strength and so forth as equated to pure nanoparticles. The present work describes the novel features of hybrid nanoparticles such as Titanium oxide (TiO2) and Copper (Cu) in the flow of Ethylene glycol (EG) under the induced magnetic field environment. The analysis covers the features of both pure nanofluid Cu/EG and hybrid nanofluid Cu-TiO2/EG. The concentration equation is amended by the activation energy term. The amalgamation of Cu-TiO2/EG exhibits improved and embellished thermal characteristics. A persuasive numerical technique named “Successive over Relaxation” is used to...
Flow and heat transfer analysis of nanofluid (cuo/water) subject to inclined magnetic field and thermal radiation: a numerical approach
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 42, Issue 5 , 2023 , Pages 1638-1647 ; 10219986 (ISSN) ; Ahmad, S ; Raza, A ; Ashraf, M ; Ali, K ; Sharif University of Technology
Iranian Institute of Research and Development in Chemical Industries
2023
Abstract
Nanofluids play an important role in order to augment of the heat transfer characteristics in many energy systems. As compared to usual fluids, nanofluids comprise better physical strength and thermal conductivity. Our aim in studying this work is to numerically interpret the flow and heat transfer features of copper oxide (CuO) nanoparticles in the coexistence of thermal radiation and inclined magnetic fields. The model equations are first simplified by the similarity transformations and then finite difference discretization is used to apply the numerical technique known as the successive over-relaxation method. We have mainly examined that how much the thermal radiation and inclined...
Dynamic response of metal foam FG porous cylindrical micro-shells due to moving loads with strain gradient size-dependency
, Article European Physical Journal Plus ; Volume 134, Issue 5 , 2019 ; 21905444 (ISSN) ; Forsat, M ; Barati, M. R ; Abdella, G. M ; Mohasel Afshari, B ; Hamouda, A. M. S ; Rabby, S ; Sharif University of Technology
Springer Verlag
2019
Abstract
The dynamic characteristics of functionally graded (FG) metal foam cylindrical micro-scale shells in contact with a moving load will be analyzed thorough this paper accounting for strain-gradient size-dependency. In the material structure of a metal foam, pores can diffuse uniformly or non-uniformly. Based upon Laplace transform, the dynamical governing equations of the first-order micro-shell model can be established in a new domain. In order to go back into the time domain, an inverse Laplace transform will be required. Thus, on can express the time response or dynamic deflection of the micro-shell under moving load. In the presented results, it is easy to see the prominence of...
Fabrication and characterization of biaxially electrospun collagen/alginate nanofibers, improved with Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides for wound healing applications
, Article International Journal of Biological Macromolecules ; 2021 ; 01418130 (ISSN) ; Parivar, K ; Hayati Roodbari, N ; Mashayekhan, S ; Amini, N ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Fabrication of scaffolds with enhanced mechanical properties and desirable cellular compatibility is critical for numerous tissue engineering applications. This study was aimed at fabrication and characterization of a nanofiber skin substitute composed of collagen (Col)/sodium alginate (SA)/ polyethylene oxide (PEO)/Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides (EPS) were prepared using the biaxial electrospinning technique. This study used collagen extracted from the bovine tendon as a natural scaffold, sodium alginate as an absorber of excess wound fluids, and GUMS16 produced exopolysaccharides as an antioxidant. Collagen was characterized using FTIR and EDS analyses. The...
Simulation analysis of MHD hybrid Cu-Al2O3/H2O nanofluid flow with heat generation through a porous media
, Article International Journal of Energy Research ; Volume 45, Issue 13 , 2021 , Pages 19165-19179 ; 0363907X (ISSN) ; Ahmad, S ; Nisar, K. S ; Faridi, A. A ; Ashraf, M ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
Hybrid nanoliquids comprise of better physical strength, mechanical resistance, thermal conductivity, and chemical stability as equated to individual nanoliquids. The present work investigates the MHD laminar flow, containing hybrid nanoparticles, with heat transfer phenomenon over a stretching sheet immersed in a porous medium. The effect of induced magnetic field has also been taken into account. The flow model PDEs are rehabilitated into ordinary ones using a persuasive tool of similarity variables. The analogous system of dimensionless equations alongside the boundary conditions is numerically treated with the Successive-Over-Relaxation (SOR) technique. Flow and heat transfer aspects of...
Simulation analysis of MHD hybrid Cu-Al2O3/H2O nanofluid flow with heat generation through a porous media
, Article International Journal of Energy Research ; Volume 45, Issue 13 , 2021 , Pages 19165-19179 ; 0363907X (ISSN) ; Ahmad, S ; Nisar, K. S ; Faridi, A. A ; Ashraf, M ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
Hybrid nanoliquids comprise of better physical strength, mechanical resistance, thermal conductivity, and chemical stability as equated to individual nanoliquids. The present work investigates the MHD laminar flow, containing hybrid nanoparticles, with heat transfer phenomenon over a stretching sheet immersed in a porous medium. The effect of induced magnetic field has also been taken into account. The flow model PDEs are rehabilitated into ordinary ones using a persuasive tool of similarity variables. The analogous system of dimensionless equations alongside the boundary conditions is numerically treated with the Successive-Over-Relaxation (SOR) technique. Flow and heat transfer aspects of...
Fabrication and characterization of biaxially electrospun collagen/alginate nanofibers, improved with Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides for wound healing applications
, Article International Journal of Biological Macromolecules ; Volume 196 , 2022 , Pages 194-203 ; 01418130 (ISSN) ; Parivar, K ; Hayati Roodbari, N ; Mashayekhan, S ; Amini, N ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Fabrication of scaffolds with enhanced mechanical properties and desirable cellular compatibility is critical for numerous tissue engineering applications. This study was aimed at fabrication and characterization of a nanofiber skin substitute composed of collagen (Col)/sodium alginate (SA)/ polyethylene oxide (PEO)/Rhodotorula mucilaginosa sp. GUMS16 produced exopolysaccharides (EPS) were prepared using the biaxial electrospinning technique. This study used collagen extracted from the bovine tendon as a natural scaffold, sodium alginate as an absorber of excess wound fluids, and GUMS16 produced exopolysaccharides as an antioxidant. Collagen was characterized using FTIR and EDS analyses. The...
Thermal-exergetic behavior of triangular vortex generators through the cylindrical tubes
, Article International Journal of Heat and Mass Transfer ; Volume 151 , 2020 ; Pesteei, S. M ; Ebrahimi Ghalinghie, H ; Hashemian, M ; Aqeel Ashraf, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, new arrangements of triangular winglet as a turbulator are numerically studied through a cylindrical tube. Triangular winglets are commonly placed on one side of a rectangular plate and inserted inside the tube. However, in present work, the winglets are located on both sides of the rectangular plate to further enhance the thermal performance of the fluid flow through the tube. Both backward and forward configurations of the winglets are analysed. Moreover, despite the importance of “latitudinal pitch of the winglets” and “winglet-plate angle” no investigation has been evaluated these parameters which will be evaluated in this work. Moreover, as no exergetic evaluation has...