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    Reliability-Based Seismic Loss Assessment of Eccentrically Braced Frame Buildings

    , M.Sc. Thesis Sharif University of Technology Godazgar, Behfar (Author) ; Dolatshahi, Kiarash (Supervisor)
    Abstract
    In this research, seismic loss of eccentrically braced frame buildings is assessed by using reliability methods. For this end, first, Bayesian linear regression is utilized to characterize the epistemic uncertainty of the problem in the form of damage models. The input of these models are mechanical and physical properties of the components, and the outputs are damage ratios. In the second step, by using the developed models and the comprehensive library of probabilistic models of Rt, reliability analysis is conducted on 4, 8, and 16 stories building located in San Jose. The limit state function is seismic loss, including repair loss, collapse loss, and demolition loss, and analysis method... 

    Nanoscale modeling of an embedded multi-shell fullerene and its application to vibrational analysis

    , Article International Journal of Engineering Science ; Volume 44, Issue 17 , 2006 , Pages 1156-1163 ; 00207225 (ISSN) Behfar, K ; Naghdabadi, R ; Sharif University of Technology
    2006
    Abstract
    In this paper, nanoscale modeling of a multi-shell fullerene embedded in an elastic medium and its application to vibrational analysis is investigated. The spherical layers of the multi-shell fullerene are concentrically nested, with carbon-carbon van der Waals interactions between them. Also, the whole multi-shell fullerene is influenced by polymer-carbon van der Waals forces from the surrounding elastic medium. The elasticity generated by the carbon-carbon bonds is assumed to be distributed isotropically over the fullerene surfaces. Following derivation of explicit equations for the motion of the multi-shell fullerene, vibrational behavior of a double-shell fullerene is analyzed and... 

    Bending stiffness of a double-layered graphene sheet using a geometrically-based analytical approach

    , Article 4th ASME Integrated Nanosystems Conference: Design, Synthesis, and Applications, Berkeley, CA, 14 September 2005 through 16 September 2005 ; 2005 , Pages 85-86 ; 0791842088 (ISBN); 9780791842089 (ISBN) Behfar, K ; Naghdabadi, R ; Sharif University of Technology
    American Society of Mechanical Engineers  2005
    Abstract
    In this article, the bending stiffness of a double-layered graphene sheet is investigated using a geometrically-based analytical approach. The analysis is based on the van der Waals interactions of atoms belonging to two neighboring sheets. The inter-atomic spacing between the adjacent layers is geometrically determined when the sheet is applied by a couple of moments in the opposite sides. The bending potential energy is obtained by summing up the potentials at discrete hexagons over the length and width of the sheet. It is observed that the bending stiffness of a double-layered graphene sheet does not depend on the length of the sheet and be a material property for the associated sheet.... 

    Nanoscale vibrational analysis of a multi-layered graphene sheet embedded in an elastic medium

    , Article Composites Science and Technology ; Volume 65, Issue 7-8 , 2005 , Pages 1159-1164 ; 02663538 (ISSN) Behfar, K ; Naghdabadi, R ; Sharif University of Technology
    2005
    Abstract
    In this paper, nanoscale vibrational analysis of a multi-layered graphene sheet embedded in an elastic medium is investigated and the corresponding natural frequencies and the associated modes are determined. The modeling is based on the fact that the elastic moduli of a graphene sheet in two perpendicular orientations are different, so the plate is considered to be anisotropic. The graphene layers stacking at the top of each other bond with carbon-carbon van der Waals forces between two adjacent ones. Also, the whole multi-layered graphene sheet is influenced by polymer-carbon van der Waals forces from the surrounding elastic medium. © 2005 Elsevier Ltd. Al rights reserved  

    General derivations for conjugate strains of eshelby-like stress tensors

    , Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 353-356 ; 0791841731 (ISBN); 9780791841730 (ISBN) Behfar, K ; Sheshmani, A ; Naghdabadi, R ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Abstract
    In this paper, a general type of Eshelby-like stress tensor is defined which is based on the right stretch tensor and is equal to the product of a general class of strain and the corresponding conjugate stress tensor. The Eshelby-like stress tensor depending on the fact that from which side the stress tensor is multiplied by, is categorized into the right-weighted and left-weighted ones. General relations for conjugate strains of Eshelby-like stress tensors are investigated using the method, based on the definition of energy conjugacy and Hill's principal axis method  

    An analytical approach to determination of bending modulus of a multi-layered graphene sheet

    , Article Thin Solid Films ; Volume 496, Issue 2 , 2006 , Pages 475-480 ; 00406090 (ISSN) Behfar, K ; Seifi, P ; Naghdabadi, R ; Ghanbari, J ; Sharif University of Technology
    2006
    Abstract
    In this paper, the bending modulus of a multi-layered graphene sheet is investigated using a geometrically based analytical approach. For this purpose, a bending potential energy is derived, based on the van der Waals interactions of atoms belonging to the two neighboring sheets of a double-layered graphene sheet. The inter-atomic spacing between the adjacent layers is determined along the line of action of the applied bending moments. The bending potential of the double-layered sheet is calculated by summing up the potentials at discrete hexagons over the length and width of the sheet. A multi-layered graphene sheet is considered as consisting of many stacking double-layers. It is observed... 

    Basis-free relations for conjugate strains of eshelby-like stress tensors

    , Article Mechanics of Materials ; Volume 39, Issue 7 , 2007 , Pages 637-642 ; 01676636 (ISSN) Behfar, S. K ; Naghdabadi, R ; Arghavani, J ; Asghari, M ; Sharif University of Technology
    2007
    Abstract
    In this paper, a general class of Eshelby-like or weighted stress tensors based on the right stretch tensor is defined as the product of a general type of Lagrangian stress tensor and a class of stretch measure. In addition, basis free relations for conjugate strains of Eshelby-like stress tensors are investigated, which are based on Hill's definition of energy conjugacy. The equations for strain tensors conjugate to Eshelby-like stress tensors are generally determined, but the case in which the conjugate strains are coaxial with the right stretch tensor is mostly investigated. © 2006 Elsevier Ltd. All rights reserved  

    Nanoscale vibrational analysis of an embedded multi-layered graphene sheet

    , Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 3 , 2004 , Pages 569-572 ; 0791841731 (ISBN); 9780791841730 (ISBN) Behfar, K ; Vafai, A ; Naghdabadi, R ; Estekanchi, H. E ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Abstract
    In this paper, nanoscale vibrational analysis of a multi-layered graphene sheet embedded in an elastic medium is investigated and the corresponding resonant modes and frequencies are determined. It is known that the elastic moduli of a graphene sheet in two orientations x, y are different, so the graphene sheet is assumed to be a general form of an orthotropic plate. The orthotropic sheets stacking at the top of each other bond with carbon-carbon van der Waals forces, also the whole multi-layered graphene sheet is influenced by polymer-carbon van der Waals forces from the surrounding elastic medium  

    Image Categorization Using Deep Learning

    , M.Sc. Thesis Sharif University of Technology Behfar, Sajad (Author) ; Jafari Siavoshani, Mahdi (Supervisor) ; Rabiee, Hamid Reza (Co-Advisor)
    Abstract
    The representation of data influences the explanation factors of data variations. Thus,the success of learner algorithms depends on the data representation. Our main contribution in this thesis is learning of high level and abstract representation using deep structure. One of the fundamental examples of representation learning is the AutoEncoders. The auto-encoder is a rigid framework that doesn’t consider explanation factors in terms of statistical concepts. So, the auto-encoders can be re-interpreted by seeing the decoder as the statistical model of interest. The role of encoder is a mechanism for inference in the model described by the decoder. Our purpose is to design such model with...