Search for: structural-change
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    Analyzing Directed Functional Brain Networks Based On Electroencephalogram Data

    , M.Sc. Thesis Sharif University of Technology Afshari, Saeedeh (Author) ; Rabiei, Hamid Reza (Supervisor)
    Over the past few years, various studies have demonstrated that the complex networks can be used to model the structure and functions of human brain. Some of these studies indi- cated that diseases such as Alzheimer, Epilepsy, and Schizophrenia can cause changes in this network. The main idea behind the methods proposed to analyze human brain’s behav- ior, is to identify regions of the brain with specific tasks. Recent studies show that multiple regions of human brain are involved in complex activities, so it’s important to detect their interactions. Using functional high resolution multichannel neurophysiological signals, like electroencephalographic (EEG) and magnetoencephalographic... 

    Estimating the change point of correlated poisson count processes

    , Article Quality Engineering ; Volume 26, Issue 2 , 2014 , Pages 182-195 ; ISSN: 08982112 Asghari Torkamani, E ; Niaki, S. T. A ; Aminnayeri, M ; Davoodi, M ; Sharif University of Technology
    Knowing the time of change would narrow the search to find and identify the variables disturbing a process. The knowledge of the change point can greatly aid practitioners in detecting and removing the special cause(s). Count processes with an autocorrelation structure are commonly observed in real-world applications and can often be modeled by the first-order integer-valued autoregressive (INAR) model. The most widely used marginal distribution for count processes is Poisson. In this study, change-point estimators are proposed for the parameters of correlated Poisson count processes. To do this, Newton's method is first used to approximate the parameters of the process. Then, maximum... 

    On low back pain: Identification of structural changes in system parameters for fatigue loaded intervertebral disc using PCA

    , Article ICIAS 2012 - 2012 4th International Conference on Intelligent and Advanced Systems: A Conference of World Engineering, Science and Technology Congress (ESTCON) - Conference Proceedings, 12 June 2012 through 14 June 2012 ; Volume 1 , June , 2012 , Pages 378-381 ; 9781457719677 (ISBN) Khan, M. F ; Malik, A. S ; Rozana, F ; Xia, L ; Nikkhoo, M ; Wang, J. L ; Parnianpour, M ; Sharif University of Technology
    This paper presents the background of low back problem caused by repetitive fatigue loading. We emphasize on mechanism of Intervertebral Disc (IVD) and conditions for which the disc does not recover its original status under repetitive work and cause low back pain. The objective of this study is to identify structural changes in system parameters for fatigue loaded intervertebral disc. Principal component analysis (PCA) is used for studying the behavioral change of spine against cyclic loading as a function of time. Percentage difference and similarity factor was calculated for the analysis. Specimens were applied with impulse testing to measure the stiffness and acceleration after fracture,... 

    Subsidy cut and its effect on tehran electricity company: A system dynamics approach

    , Article Proceedings of the 2012 - Summer Computer Simulation Conference, SCSC 2012, Part of SummerSim 2012 Multiconference ; Volume 44, Issue 10 , 2012 , Pages 113-120 ; 9781618399847 (ISBN) Mehmanchi, E ; Fard, S. Z
    In recent years, subsidy payment has been made a main challenge for governments due to growth of population and energy price in global markets. Targeted subsidy plan has been implemented in Iran since last year, and this article discusses its effects on costs and revenues of Tehran Electricity Company as one of the major subdivisions of Iran's electricity industry. In the new system, structural changes have been made in electricity tariffs, so it is not possible to predict the future trends in electricity consumption only based on the past consumptions. In order to model the decision making structure in the recent conditions, a system dynamics method is applied. In addition to modeling the... 

    Molecular dynamics simulation and MM-PBSA calculations of sickle cell hemoglobin in dimer form with Val, Trp, or Phe at the lateral contact

    , Article Journal of Physical Organic Chemistry ; Volume 23, Issue 9 , March , 2010 , Pages 866-877 ; 08943230 (ISSN) Abroshan, H ; Akbarzadeh, H ; Parsafar, G. A ; Sharif University of Technology
    As the delay time and hence nuclei formation play a crucial role in the pathophysiology of sickle cell disease, MD simulation and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) calculations have been performed on three systems of hemoglobin; namely dimer of hemoglobin with valine (Hb S), tryptophan (Hbβ6W), and phenylalanine (Hbβ6F) at β6 position. The structural changes due to these aromatic substitutions are investigated. It is shown that β subunits have significant impact on the differences between a dimer and other crystal structures. Transition from a dimer to polymer for Hb S system affects the donor molecule more than that of the acceptor. In the case of donor and... 

    Influence of annealing on the electrochemical behavior of finemet amorphous and nanocrystalline alloy

    , Article Journal of Materials Science ; Volume 45, Issue 2 , 2010 , Pages 546-551 ; 00222461 (ISSN) Asghari Shivaee, H ; Nozad Golikand, A ; Madaah Hosseini, H. R ; Asgari, M ; Sharif University of Technology
    The electrochemical corrosion behavior of finemet alloy at various heat treatment temperatures was investigated. Thermal behavior and structural changes were studied using differential scanning calorimetry and X-ray diffractometry, respectively. The electrochemical corrosion of amorphous and annealed samples was investigated in 0.10 M NaOH solution using electrochemical impedance spectroscopy and linear sweep voltammetery. Changes in morphology of the samples before and after corrosion were characterized using optical microscope. The results showed that structural relaxation and nanocrystallization during the heat treatment improved corrosion behavior of the alloy. The heat-treated alloy at... 

    Structural changes of radial forging die surface during service under thermo-mechanical fatigue

    , Article Materials Science and Engineering A ; Volume 527, Issue 1-2 , 2009 , Pages 98-102 ; 09215093 (ISSN) Nematzadeh, F ; Akbarpour, M. R ; Kokabi, A. H ; Sadrnezhaad, S. k ; Sharif University of Technology
    Radial forging is one of the modern open die forging techniques and has a wide application in producing machine parts. During operation at high temperatures, severe temperature change associated with mechanical loads and the resultant wearing of the die surface lead to intense variation in strain on the die surface. Therefore, under this operating condition, thermo-mechanical fatigue (TMF) occurs on the surface of the radial forging die. TMF decreases the life of the die severely. In the present research, different layers were deposited on a 1.2714 steel die by SMAW and GTAW, with a weld wire of UDIMET 520. The microstructure of the radial forging die surface was investigated during welding... 

    Protein G selects two binding sites for carbon nanotube with dissimilar behavior; a molecular dynamics study

    , Article Journal of Molecular Graphics and Modelling ; Volume 87 , 2019 , Pages 257-267 ; 10933263 (ISSN) Ebrahim Habibi, M. B ; Ghobeh, M ; Aghakhani Mahyari, F ; Rafii Tabar, H ; Sasanpour, P ; Sharif University of Technology
    Elsevier Inc  2019
    Background: Study of nanostructure-protein interaction for development of various types of nano-devices is very essential. Among carbon nanostructures, carbon nanotube (CNT) provides a suitable platform for functionalization by proteins. Previous studies have confirmed that the CNT induces changes in the protein structure. Methods: Molecular dynamics (MD) simulation study was employed to illustrate the changes occurring in the protein G (PGB) in the presence of a CNT. In order to predict the PGB surface patches for the CNT, Autodock tools were utilized. Results: Docking results indicate the presence of two different surface patches with diverse amino acids: the dominant polar residues in the...