Loading...
Search for: safdari-shadloo--mostafa
0.149 seconds

    Modeling Multiphase Fluid Flow Using SPH

    , M.Sc. Thesis Sharif University of Technology Safdari Shadloo, Mostafa (Author) ; Taghizadeh Manzari, Mehrdad (Supervisor)
    Abstract
    Smoothed Particle Hydrodynamics (SPH) is a Lagrangian method for simulation of fluid flow. Movable particles are used to interpolate fluid properties instead of fixed Eulerian grids in this method. By essence, the aforesaid particles are movable points which carry the fluid properties such as temperature, enthalpy, density, etc. these variables can also be the stress, strain or the rheological properties of the fluid. Thus, this method needs no grids and the fluid properties are calculated using an interpolation mechanism which classifies this method as meshless. A computational code is designed using SPH for the simulation of multiphase flows. Usage of the Lagrangian formulation has made it... 

    Investigating Ethical Consequences of the Information and Communication Technologies (ICT) with Respect to Luciano Floridi’s Philosophy and Ethics of Information

    , M.Sc. Thesis Sharif University of Technology Safdari Sharabiani, Abootaleb (Author) ; Taghvai, Mostafa (Supervisor)
    Abstract
    The main purpose of this dissertation is to give an ethical evaluation of one of the consequences of ICT. Since these technologies are present in every corner of our personal and social life, recognizing their ethical and social consequences are of vital importance. The present dissertation, which is set up in 3 chapters, is allocated for evaluating one of these consequences. In the first chapter which is the first step of our overall argument indeed, one of recent theories in Cognitive Psychology and memory studies, namely Working Memory will be introduced. In the second chapter, introducing another theory in Cognitive Psychology namely Cognitive Load Theory, the role of Working Memory in... 

    An Active Learning Algorithm for Spam Filtering

    , M.Sc. Thesis Sharif University of Technology Shadloo, Maryam (Author) ; Beigy, Hamid (Supervisor)
    Abstract
    Content-based spam filtering problem is defined as classifying input emails into spam and legitimate emails. so it is considered as an application of supervised-learning. The supervised learning methods often require a large training set of labelled emails to attain good accuracy and the users should label huge amount of emails. In reality, it is not reasonable to expect users to do this. To address this issue and reduce number of labelling request from user active learning techniques can be used. The goal of active Learning algorithms is to achieve appropriate accuracy by using fewer amounts of labelled data in comparison with supervised-learning methods.In this thesis two active learning... 

    Exploiting structural information of data in active learning

    , Article Artificial Intelligence and Soft Computing: Lecture Notes in Computer Science ; Volume 8468 LNAI, Issue PART 2 , 2014 , Pages 796-808 Shadloo, Maryam ; Beigy, Hamid ; Haghiri, Siavash ; Sharif University of Technology
    2014
    Abstract
    In recent years, the active learning algorithms have focused on combining correlation criterion and uncertainty criterion for evaluating instances. Although these criteria might be useful, applying these measures on whole input space globally may lead to inefficient selected instances for active learning. The proposed method takes advantage of clustering to partition input space to subspaces. Then it exploits both labeled and unlabeled data locally for selection of instances by using a graph-based active learning. We define a novel utility score for selecting clusters by combining uncertainty criterion, local entropy of clusters and the factor of contribution of each cluster in queries.... 

    An example of non-embeddability of the Ricci flow

    , Article Annals of Global Analysis and Geometry ; Volume 55, Issue 4 , 2019 , Pages 681-685 ; 0232704X (ISSN) Safdari, M ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    For an evolution of metrics (M, g t ) there is a t-smooth family of embeddings e t : M→ R N inducing g t , but in general there is no family of embeddings extending a given initial embedding e. We give an example of this phenomenon when g t is the evolution of g under the Ricci flow. We show that there are embeddings e inducing g which do not admit of t-smooth extensions to e t inducing g t for any t> 0. We also find hypersurfaces of dim > 2 that will not remain a hypersurface under Ricci flow for any positive time. © 2019, Springer Nature B.V  

    Global optimal regularity for variational problems with nonsmooth non-strictly convex gradient constraints

    , Article Journal of Differential Equations ; Volume 279 , 2021 , Pages 76-135 ; 00220396 (ISSN) Safdari, M ; Sharif University of Technology
    Academic Press Inc  2021
    Abstract
    We prove the optimal W2,∞ regularity for variational problems with convex gradient constraints. We do not assume any regularity of the constraints; so the constraints can be nonsmooth, and they need not be strictly convex. When the domain is smooth enough, we show that the optimal regularity holds up to the boundary. In this process, we also characterize the set of singular points of the viscosity solutions to some Hamilton-Jacobi equations. Furthermore, we obtain an explicit formula for the second derivative of these viscosity solutions; and we show that the second derivatives satisfy a monotonicity property. © 2021 Elsevier Inc  

    Double obstacle problems and fully nonlinear PDE with non-strictly convex gradient constraints

    , Article Journal of Differential Equations ; Volume 278 , 2021 , Pages 358-392 ; 00220396 (ISSN) Safdari, M ; Sharif University of Technology
    Academic Press Inc  2021
    Abstract
    We prove the optimal W2,∞ regularity for fully nonlinear elliptic equations with convex gradient constraints. We do not assume any regularity about the constraints; so the constraints need not be C1 or strictly convex. We also show that the optimal regularity holds up to the boundary. Our approach is to show that these elliptic equations with gradient constraints are related to some fully nonlinear double obstacle problems. Then we prove the optimal W2,∞ regularity for the double obstacle problems. In this process, we also employ the monotonicity property for the second derivative of obstacles, which we have obtained in a previous work. © 2021 Elsevier Inc  

    Series solution for heat transfer of continuous stretching sheet immersed in a micropolar fluid in the existence of radiation

    , Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 23, Issue 2 , 2013 , Pages 289-304 ; 09615539 (ISSN) Shadloo, M. S ; Kimiaeifar, A ; Bagheri, D ; Sharif University of Technology
    2013
    Abstract
    Purpose - The purpose of this paper is to study a two-dimensional steady convective flow of a micropolar fluid over a stretching sheet in the presence of radiation with constant temperature. Design/methodology/approach - The corresponding momentum, microrotation and energy equations are analytically solved using homotopy analysis method (HAM). Findings - To validate the method, investigate the accuracy and convergence of the results, a comparison with existing numerical and experimental results is done for several cases. Finally, by using the obtained analytical solution, for the skin-friction coefficient and the local Nusselt number as well as the temperature, velocity and angular velocity,... 

    Genuine empathy with inanimate objects

    , Article Phenomenology and the Cognitive Sciences ; Volume 20, Issue 5 , 2021 , Pages 831-846 ; 15687759 (ISSN) Safdari Sharabiani, A ; Sharif University of Technology
    Springer Science and Business Media B.V  2021
    Abstract
    How do we enter into empathic relations with inanimate objects (IO)? Do we indirectly infer that they possess mental states, or directly perceive them as mental things? In recent years these questions have been addressed by a number of authors. Some argue in favor of an indirect approach that involves mediatory procedures; others defend a direct approach that postulates no intermediate. In this paper I argue on the side of the latter. I show that Simulation Theory (ST), one of the most elaborated versions of the indirect approach, does not have the capacity to account for our empathy with IO. Investigating ST paves the way for criticizing a special kind of indirect theory, namely Imaginative... 

    A fully explicit incompressible Smoothed Particle Hydrodynamics method for multiphase flow problems

    , Article Engineering Analysis with Boundary Elements ; Volume 143 , 2022 , Pages 501-524 ; 09557997 (ISSN) Vakilha, M ; Hopp Hirschler, M ; Shadloo, M. S ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Multiphase flow is a challenging area of computational fluid dynamics (CFD) due to their potential large topological change and close coupling between the interface and fluid flow solvers. As such, Lagrangian meshless methods are very well suited for solving such problems. In this paper, we present a new fully explicit incompressible Smoothed Particle Hydrodynamics approach (EISPH) for solving multiphase flow problems. Assuming that the change in pressure between consecutive time-steps is small, due to small time steps in explicit solvers, an approximation of the pressure for following time-steps is derived. To verify the proposed method, several test cases including both single-phase and... 

    The Ricci Flow with Applications to the Poincare and Calabi Conjectures

    , M.Sc. Thesis Sharif University of Technology Safdari, Mohammad (Author) ; Bahreini, Alireza (Supervisor)
    Abstract
    Poincare conjecture is one of the rst eorts for classifying 3-manifolds that was stated in the begining of 20th century. Eorts for proving this conjecture continued for about 100 years and nally Perelman has solved it in 2003. He has used Ricci ow which has been invented by Richard Hamilton in the early 80's. In this thesis rst we will introduce Ricci ow and will state the results before Perelman such as short time and long time existence of solution. Then we will mention some applications of Ricci ow and will state an explanation of the proof of uniformization and Calabi conjecture by Ricci ow. After that we start the main part of the thesis. In this part we will montion one of the... 

    Weak Solutions of the Euler Equations and Onsager’s Conjecture

    , M.Sc. Thesis Sharif University of Technology Haghshenas, Mahdi (Author) ; Safdari, Mohammad (Supervisor)
    Abstract
    The Onsager's conjecture is concerned with the dichotomy between rigidity and flexibility of weak solutions of incompressible Euler equations. Lars Onsager conjectured that weak solutions of Euler equations that are not smooth enough could be dissipative, even without the help of viscosity. On the other hand, it is well known that $C^1$ solutions conserve energy. Onsager conjectured that C^(1/3) regularity marks the threshold for this dichotomy. In other words, Hölder continuous solutions with Hölder exponent greater than 1/3 conserve the energy, while for every Hölder exponent less than 1/3, there are dissipative Hölder continuous solutions. The threshold 1/3 is intimately tied with... 

    Influence of quantum effect on deviation from linear isotherm regularity

    , Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 555-560 ; 10263098 (ISSN) Safdari, F ; Parsafar, G. A ; Sharif University of Technology
    2012
    Abstract
    A general regularity was found based on an effective pair potential of Lennard-Jones LJ (12, 6), for both dense, nonmetallic and nonionic fluids and solids according to which (Z-1) v2 linearly varies with respect to ρ2 for each isotherm, and this equation of state (EoS I) is known as LIR. However, despite the fact that Ne is a simple spherical species, unexpectedly, its solid and liquid phases both show a significant deviation from EoS I. In this work, we have investigated the accuracy of the EoS I for other systems, including quantum light molecules, such as D 2, H 2 and He, in both fluid and solid states at different temperatures. Like Ne, we have noticed that these systems do not well... 

    A Review of Some Results of Kac’s Program in Kinetic Theory

    , M.Sc. Thesis Sharif University of Technology Saberbaghi, Hamid Reza (Author) ; Safdari, Mohammad (Supervisor)
    Abstract
    This thesis is devoted to the study of suitable functional frameworks for proving propagation of chaos and mean-field limit of nonlinear Vlasov-type equations for indistinguishable particles. The Kac model is a classic example and the motivation of this functional structure. On the one hand, Kac considered a spatially homogeneous gas, and on the other hand, he reduced the problem to one-dimensional collisions and dropped the conservation of momentum assumption. Therefore, he obtained a simplified version of the Boltzmann equation, which is named after him, the Kac equation. The main results which we study are quantitative estimates
    on the decay of fluctuations around the deterministic... 

    Determinants of the Quality of Corporate Social Responsibility Disclosures in Iran’s Stock Market

    , M.Sc. Thesis Sharif University of Technology Safdari, Ali (Author) ; Ebrahimnejad, Ali (Supervisor)
    Abstract
    This study examines the quality of Corporate Social Responsibility (CSR) disclosure among publicly listed companies in Iran and identifies the factors that influene it. The research sample consists of 546 companies listed on the Tehran Stock Exchange and Iran Fara Bourse, covering the period from February 2023 to January 2024. Data were extracted from audited financial statements and the annual reports of the companies' boards of directors. In the first part of the study, a CSR disclosure quality index comprising 39 factors was developed. The annual reports of the companies were then analyzed to calculate a disclosure score for each company. The average CSR disclosure quality score was... 

    Equation of State for Dense Systems of Light Molecules in Fluid and Solid States

    , M.Sc. Thesis Sharif University of Technology Safdari, Fatemeh (Author) ; Parsafar, Gholam Abbas (Supervisor)
    Abstract
    A general regularity has been found based on an effective pair potential of Lennard-Jones LJ (12, 6) for both dense nonmetallic and nonionic fluids and solids; namely, (Z-1)V2 linearly varies with respect to ρ2, this equation of state (EoS I) is known as LIR. The other equation of state (EoS II), according to wich the isotherm of (Z-1)V2 is linear in term of 1/ρ, wich gives a good description for the metallic and ionic fluids and solids. This equation of state was suggested based on an effective pair potential of LJ (6, 3). Unexpectedly, solid and liquid Ne indicates a significant deviations from EoS I. Recently, a general equation of state (EoS III) based on an effective near-neighbor pair... 

    The Nature of Folk Psychology and Its Implications for Designing Artificial Agents and Humanoid Robots

    , Ph.D. Dissertation Sharif University of Technology Safdari Sharabiani, Abootaleb (Author) ; Azadegan, Ebrahim (Supervisor)
    Abstract
    How do we enter into empathic relations with inanimate objects (IO)? Do we indirectly infer that they possess mental states, or directly perceive them as mental things? In recent years these questions have been addressed by a number of authors. Some argue in favor of an indirect approach that involves mediatory procedures; others defend a direct approach that postulates no intermediate. In this paper I argue on the side of the latter. I show that Simulation Theory (ST), one of the most elaborated versions of the indirect approach, does not have the capacity to account for our empathy with IO.Investigating ST paves the way for criticizing a special kind of indirect theory, namely Imaginative... 

    Stability of the Schwarzschild Family of Solutions in General Relativity

    , M.Sc. Thesis Sharif University of Technology Chaman Motlagh, Abolfazl (Author) ; Safdari, Mohammad (Supervisor)
    Abstract
    In 1952, Choquet-Bruhat proved the well-posedness of the Cauchy problem for Einstein’s equation, and demonstrated that a given initial data on a Cauchy hypersurface in spacetime propagates forward in time as a solution to the wave equation. It took nearly half a century for mathematicians to build the necessary tools and techniques for proving the stability of the most basic solution of Einstein’s vacuum equations (EVE), namely Minkowski spacetime. In 1993, Christodoulou and Klainerman showed the global nonlinear stability of this solution using the concept of a double null gauge. The Schwarzschild solution, introduced by Karl Schwarzschild in 1916 for spherically symmetric spacetimes as an... 

    Regularity of Area-Minimizing Currents

    , M.Sc. Thesis Sharif University of Technology Shahid Kalhori, Mohsen (Author) ; Safdari, Mohammad (Supervisor)
    Abstract
    This research introduces temperature measurement by a non-intrusive pyrometric method of the ratio of two colors of soot. For pyrometry, the spectral sensitivity of the Nikon D7100 camera was obtained by developing a neural network based on the results of photographing colored papers and their spectrum, and this camera was used for temperature measurement. Based on the dependence of soot radiation on temperature and the spectral sensitivity of the camera, a calibration chart has been extracted on the ratio of the green channel to the red channel of the camera with the soot temperature, which is used to produce the temperature contour using the flame image. The temperature contour of... 

    Optimization of operating parameters and rate of uranium bioleaching from a low-grade ore

    , Article Journal of Radioanalytical and Nuclear Chemistry ; Vol. 301, issue. 2 , 2014 , pp. 341-350 ; ISSN: 02365731 Rashidi, A ; Roosta-Azad, R ; Safdari, S. J ; Sharif University of Technology
    2014
    Abstract
    In this study the bioleaching of a low-grade uranium ore containing 480 ppm uranium has been reported. The studies involved extraction of uranium using Acidithiobacillus ferrooxidans derived from the uranium mine samples. The maximum specific growth rate (μ max) and doubling time (t d) were obtained 0.08 h-1 and 8.66 h, respectively. Parameters such as Fe2+ concentration, particle size, temperature and pH were optimized. The effect of pulp density (PD) was also studied. Maximum uranium bio-dissolution of 100 ± 5 % was achieved under the conditions of pH 2.0, 5 % PD and 35 °C in 48 h with the particles of d 80 = 100 μm. The optimum concentration of supplementary Fe2+ was dependent to the PD....