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    Simulation of endurance time excitations via wavelet transform

    , Article Iranian Journal of Science and Technology - Transactions of Civil Engineering ; Volume 43, Issue 3 , 2019 , Pages 429-443 ; 22286160 (ISSN) Mashayekhi, M ; Estekanchi, H. E ; Vafai, H ; Sharif University of Technology
    Springer International Publishing  2019
    Abstract
    This paper puts forth a wavelet-based methodology for generating endurance time (ET) excitations. Conventional simulating practice expresses signals by acceleration values which are then computed via unconstrained nonlinear optimization. Dynamic characteristics of signals, including frequency content, are not represented directly in this type of variable definition. In this study, a new algorithm is developed to generate ET excitations in discrete wavelet transform (DWT) space. In this algorithm, signals are represented by transform coefficients. In addition, objective functions are modified in order to obtain transform coefficients and return the objective function values. The proposed... 

    Critique of Kuhns Histirical Perspective from Gadamerian Perspective

    , M.Sc. Thesis Sharif University of Technology Behzadi Moghaddam, Mohammad Reza (Author) ; Moeinzadeh, Mahdi (Supervisor) ; Taghavi, Mostafa (Supervisor)
    Abstract
    Truth and Method is one of the two or three most important works of this century on the philosophy of humanistic studies. The book is powerful, exciting, but undeniably difficult. Published when Gadamer was sixty, it gathers the ripe fruit of a lifetime's reading, teaching, and thinking. Because it is immersed in German philosophy and scholarship, the book is even more challenging for an American reader. An emerging body of commentary in English as well as the many shorter essays Gadamer has, happily, lived to write and which are increasingly available in translation provide additional means of access to his thought. Truth and Method, however, remains his magnum opus, the comprehensive and... 

    Distributed Denial of Service Mitigation

    , M.Sc. Thesis Sharif University of Technology Baki, Shahryar (Author) ; Kharrazi, Mehdi (Supervisor)
    Abstract
    Denial of service (DoS) attacks is the main challenges of service providers due to their purpose to makes their service unavaillable. Nowadays this attacks are changed from centralized to distributed (DDoS) by means of botnets. In addition botnets allow attackers to launch attack on higher layers of network, such as application layer. In new application layer DDoS attacks, attacker send HTTP requests to waste victims resources. In addition, attacker can start attack during flash crowd event which makes attack more undetectable. In this research, in order to migigating such attacks, we introduced a method based on user’s history.
    This history consist of user’s request rate for each... 

    A Historical Analysis of the Evolution of Dominant Industrial Development Approaches in the Age of Pahlavi in Iran

    , M.Sc. Thesis Sharif University of Technology Hosseini, Siavash (Author) ; Souzanchi Kashani, Ebrahim (Supervisor)
    Abstract
    Our country in no measure is considered as an industrial one, despite its chain of small, medium and large industries. The vague, general “developing” term might be the best term to assign to economic-industrial condition of our country. We have a fairly limited number of big industrial firms (BIF) which could continue operation without state’s supports in a world BIFs are considered as the key indices in industrial development. The question comes to mind with reading what came above is this study’s main question, “What went wrong?”. This study follows the historical approach to the question through a comprehensive case study. Historical case-study thus is our main research approach here.... 

    Endurance time method in the linear seismic analysis of shell structures

    , Article International Journal of Civil Engineering ; Volume 10, Issue 3 , 2012 , Pages 169-178 ; 17350522 (ISSN) Tavazo, H ; Estekanchi, H. E ; Kaldi, P ; Sharif University of Technology
    IJCE  2012
    Abstract
    Endurance Time (ET) method is a response history based analysis procedure that can be used for estimating the seismic response of structures at different excitation levels in each response history. This seismic analysis method utilizes specific intensifying acceleration functions to analyze seismic behaviors. One of the potential applications of the ET method is in the seismic assessment of shell structures. In this study, a procedure for linear seismic analysis of shell structures is proposed and applications of this method is investigated for several cases of shell structures. These structures are analyzed under three ET acceleration functions in one direction and the results are compared... 

    Significance of effective number of cycles in endurance time analysis

    , Article Asian Journal of Civil Engineering ; Volume 13, Issue 5 , 2012 , Pages 647-657 ; 15630854 (ISSN) Mashayekhi, M ; Estekanchi, H. E ; Sharif University of Technology
    AJCE  2012
    Abstract
    Endurance Time (ET) method is a dynamic analysis procedure using intensifying accelerograms which can be used to assess the structural performance at different excitation levels. In generation process of current ET accelerograms, the compatibility between acceleration spectrum produced by the ET accelerograms and acceleration spectrum associated with the real ground motions is applied, whereas the duration consistency is not directly considered. It is generally accepted that the strong-motion duration can strongly influence the response of structures which have stiffness or strength degrading characteristics. In this study, the number of cycles that a structure should resist due to a ground... 

    Nonlinear analysis of aboveground anchored steel tanks using endurance time method

    , Article Asian Journal of Civil Engineering ; Volume 12, Issue 6 , 2011 , Pages 731-750 ; 15630854 (ISSN) Alembagheri, M ; Estekanchi, H. E ; Sharif University of Technology
    Abstract
    Aboveground steel tanks are widely utilized in residential and industrial areas, and assurance of their seismic safety is a very important engineering consideration. In this paper, nonlinear response of these tanks using a new dynamic pushover procedure called Endurance Time (ET) method along with conventional nonlinear response history (RHA) is studied. The comparison between the results of RHA and ET method shows reasonable consistency. Based on the level of accuracy observed in this research, it is concluded that ET method can effectively be used in predicting seismic performance of anchored tanks. By considerably reducing the number of required response history analyses for estimating... 

    Endurance time method: Exercise test applied to structures

    , Article Asian Journal of Civil Engineering ; Volume 10, Issue 5 , 2009 , Pages 559-577 ; 15630854 (ISSN) Esmaeilpour Estekanchi, H ; Tajmir Riahi, H ; Vafai, A ; Sharif University of Technology
    Building and Housing Research Center (BHRC)  2009
    Abstract
    Endurance Time (ET) method is a new dynamic analysis procedure that aims at estimating seismic performance of structures by subjecting them to predesigned intensifying acceleration. These acceleration functions are designed in a way that they approximately simulate earthquakes with different intensities through their duration. Performance of the structure is judged based on its behavior for different intensity measures through time. A set of three acceleration functions have been produced using the ET concept by applying optimization techniques. These acceleration functions are designed in such a way that their response spectrum, while complying with typical code design spectra, intensify... 

    A state-of-knowledge review on the endurance time method

    , Article Structures ; Volume 27 , 2020 , Pages 2288-2299 Estekanchi, H. E ; Mashayekhi, M ; Vafai, H ; Ahmadi, G ; Mirfarhadi, S. A ; Harati, M ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The endurance time method is a time history dynamic analysis in which structures are subjected to predesigned intensifying excitations. This method provides a tool for response prediction that correlates structural responses to the intensity of earthquakes with a considerably less computational demand as compared to conventional time history analysis. The endurance time method is being used in different areas of earthquake engineering, such as performance-based assessment and design, life-cycle cost-based design, value-based design, seismic safety, seismic assessment, and multi-component seismic analysis. Successful implementation of the endurance time method relies heavily on the quality of... 

    Modified procedure of lead rubber isolator design used in the reinforced concrete building

    , Article Structures ; Volume 27 , 2020 , Pages 2245-2273 Kazeminezhad, E ; Kazemi, M. T ; Mirhosseini, S. M ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    Earthquakes are natural phenomena that damage structures and buildings and their equipment. Preventing the transfer of earthquake vibration to the buildings is important to protect the residents and reduce the damage. Base isolation with lead rubber isolator is one of the desirable methods to prevent the transfer of seismic to buildings. Many parameters are involved in the design of these isolators and some of them are unknown at the beginning of the design. Therefore, iterative methods are required to design these isolators. This research described two procedures for isolator design, First, usual design procedure based on AASHTO and ASCE7 codes and second, design based on the performance... 

    Optimal distribution of friction dampers to improve the seismic performance of steel moment resisting frames

    , Article Structures ; Volume 37 , 2022 , Pages 624-644 ; 23520124 (ISSN) Moghaddam, H ; Afzalinia, F ; Hajirasouliha, I ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    This study aims to develop a low computational cost framework to optimize the seismic performance of the steel moment-resisting frames (SMRFs) equipped with friction dampers at different performance levels. To achieve the optimal design of dampers in a structure, a novel approach called adaptive optimisation technique (AOT) is adopted. The basis of this method is to achieve a uniform distribution of damage (UDD) in the structure to exploit the maximum energy dissipation capacity of the dampers. The optimisation objective is to obtain the best position of friction dampers and minimize their slip-threshold force to satisfy a predefined inter-story drift (i.e. selected performance target). The... 

    Evaluation of Demand Modifier Factor ,M, in FEMA356 for Concrete Structures Under Near-Field Earthquakes

    , M.Sc. Thesis Sharif University of Technology Mohhamad Rahimi, Majid (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    Abstract
    On the average, ten thousand people die annually due to earthquakes. A UNESCO study gives damage losses amounting to ten billion dollars within the years 1926 to 1950 from earthquakes. These data shows the importance of earthquake issue that causes the scientists to pay special attention to this subject. In despite of significant improvements in many of scientific fields, earthquake is still remains as an unknown event without the possibility of predicting its time and location of occurrence. Because of that, a large effort has been paid for rehabilitation of structures to prevent the human loss and maintaining the necessary life safety. In this regard, various guidelines have been proposed... 

    Nonlinear seismic assessment of steel moment frames under bidirectional loading via endurance time method

    , Article Structural Design of Tall and Special Buildings ; Vol. 23, issue. 6 , April , 2014 , p. 442-462 ; ISSN: 15417794 Valamanesh, V ; Estekanchi, H. E ; Sharif University of Technology
    Abstract
    In this paper, considering horizontal components of seismic excitation, an algorithm for the nonlinear multi-component analysis of building structures by the Endurance Time (ET) method is proposed, and results of the ET method for various steel moment frames with one to seven stories are verified by comparing with the results from Nonlinear Time History Analysis with use of two different sets of ground motions. In addition, several parameters such as eccentricities and irregularities in structure, rotational and lateral stiffness, effect of hysteresis type and ductility have been considered for sensitivity analysis on results, obtained by ET method. Results show that on the basis of... 

    Endurance time method-application in nonlinear seismic analysis of single degree of freedom systems

    , Article Journal of Applied Sciences ; Volume 9, Issue 10 , 2009 , Pages 1817-1832 ; 18125654 (ISSN) Tajmir Riahi, H ; Ismail pour Estekanchi, H ; Vafai, A ; Sharif University of Technology
    2009
    Abstract
    Endurance Time (ET) method has been introduced as a lime-history based dynamic analysis procedure. In this method, structures are subjected to a gradually intensifying acceleration function. Performance of the structures is assessed based on the length of the time interval that they can satisfy required performance objectives. In this study, some fundamental concepts of ET method are explained and the potentials and limitations of this procedure in nonlinear seismic analysis of SDOF structures are investigated. A numerical optimization procedure for generating ET acceleration functions that are compatible with ground motions are explained. Results of ET analysis for inelastic SDOF systems... 

    Ductile steel plate external end diaphragms for steel tub girder straight highway bridges

    , Article Earthquake Engineering and Engineering Vibration ; Volume 19, Issue 3 , July , 2020 , Pages 759-777 Maleki, S ; Dolati, A ; Sharif University of Technology
    Institute of Engineering Mechanics (IEM)  2020
    Abstract
    The end diaphragm of bridges are normally designed to resist lateral seismic forces imposed on the superstructure in earthquake prone regions. Using ductile diaphragms with high deformation capacity could reduce the seismic demands on the substructure and prevent costly damage under strong ground motions. The end diaphragms of steel tub girder bridges with high lateral stiffness and dominant shear behavior have a potential to be used as ductile fuse elements. In this study, a steel plate shear diaphragm (SPSD) is introduced as an external end diaphragm of tub girder steel bridges to reduce the seismic demands imposed on the substructure. Quasi static nonlinear analyses were conducted to... 

    A Security Model based on Modal Description Logic for Semantic Web

    , M.Sc. Thesis Sharif University of Technology Faghihekhorasani, Fathiyeh (Author) ; Jalili, Rasool (Supervisor)
    Abstract
    With the growth of semantic-aware environments, such as semantic web, new security requirements are imposed in access control procedures. An access control model for semantic web should take the semantic relationships (in three scopes of subject, object and action) into account in its access decisions. Considering the advantages of logic based models and description logic foundation of semantic web, we use the description logic as a basis to propose access control models in this environment. On the other hand, in some applications, such as e-banking environments, policy definition with the constraint(s) based on previous users’ accesses might be crucial. To consider this aspect, in this... 

    Pushover Analysis for Soil-Structure Systems

    , M.Sc. Thesis Sharif University of Technology Haeri, Mohammad Hassan (Author) ; Ghannad, Mohammad Ali (Supervisor)
    Abstract
    Controlling damage level of structures for an earthquake with certain intensity is the main purpose in seismic performance based design. This is done by estimating and confining the structure displacements and related global and local response parameters. Even though nonlinear time history analysis method is the most exact method for predicting seismic behavior of structures, but its application is limited because of being complex. Nonlinear static analysis procedure (Pushover analysis) which is based on analyzing the structure subjected to the incremental lateral load is an alternative method that has been recommended by recent structural codes. In order to consider the soil-structure... 

    Application of Endurance Time Method in Seismic Analysis of Bridges

    , M.Sc. Thesis Sharif University of Technology Ghaffari, Esmaeil (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)
    Abstract
    In this research the appilication of a new method named Endurance Time (ET) analysis in seismic analysis of multi span bridges in linear and nonlinear ranges is investigated. Endurance Time is a time history based method of seismic analysis. In this method structure is subjected to an intensifying predefined acceleration function and different damage indices of the structure are evaluated through analysis time. The Endurance Time criterion and the Endurance Time acceleration functions have been generated in previous researchs of ET group. Using 7 earthquake records which are selected from hundred ones of PEER database based on FEMA p695 recommendations, several scaling methods are used to... 

    Parameter Reduction of Wavelet Transformation for Increasing the Accuracy of Integrated and Automatic History Matching

    , M.Sc. Thesis Sharif University of Technology Dehghani, Amin (Author) ; Pishvaie, Mahmoud Reza (Supervisor) ; Bozorgmehry, Ramein (Supervisor)
    Abstract
    One of problemsin an inverse problem like history matching is there is no unique solution. This means that maybe several diferent permeability maps can correctly reproduced the history of fieldt but there is no garanttee that these maps accurately predidct reservoir production behavior. One way to face and deal with this problem, except manipulation of solution and optimization algorithm (inverse modeling) is to use other data sources like seismic data, Variogram, pore volume, and fracture density or any other parameter obtained from geostatistical investigations.Multi-resolution wavelet analysis can be an appropriate tool to gather the necessary information to characterize the inverse model... 

    BlogDisc: A system for automatic discovery and accumulation of persian blogs

    , Article 2006 International Conference on Systems, Computing Sciences and Software Engineering, SCSS 2006, Part of the International Joint Conferences on Computer, Information, and Systems Sciences, and Engineering, CISSE 2006, 4 December 2006 through 14 December 2006 ; 2007 , Pages 269-273 ; 9781402062636 (ISBN) Sheykh Esmaili, K ; Abolhassani, H ; Abbassi, Z ; Sharif University of Technology
    2007
    Abstract
    One of the important elements of the new generation of the Web is the emergence of blogs. Currently a considerable number of users are creating content using blogs. Although Persian blogs have a short history, they have improved significantly during this short period. Because of fundamental differences between Persian and other languages, limited work has been done to analyze Persian blogs. In this work, a system named BlogDisc for automatic discovery and accumulation of Persian blogs is developed. This system uses content as well as link structure of the blogs. As an important part of this research, we propose an algorithm to recognize blogs that are not hosted on special blog hosts. © 2007...