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    Structural reliability approach to analysis of probabilistic seismic hazard and its sensitivities

    , Article Bulletin of Earthquake Engineering ; Volume 17, Issue 3 , 2019 , Pages 1331-1359 ; 1570761X (ISSN) Rahimi, H ; Mahsuli, M ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    This paper presents a new probabilistic framework for seismic hazard assessment and hazard sensitivity analysis. Hazard in this context means the probability of exceeding a measure of ground shaking intensity, such as peak ground acceleration and spectral acceleration. The main components of the proposed framework include structural reliability methods to estimate exceedance probabilities and their sensitivities, and multiple probabilistic models for earthquake occurrence, magnitude, location, and ground motion. This paper presents two analysis approaches. The first approach utilizes the first- and second-order reliability methods and importance sampling. This approach efficiently yields the... 

    A Critique on the Concept of Reliability of Science in Douglas's Philosophy of Science

    , M.Sc. Thesis Sharif University of Technology Rahimi, Ali (Author) ; Taqavi, Mostafa (Supervisor)
    Abstract
    Does the direct involvement of social values in science, damage the reliability of scientific claims? Using recent debates in the relation between science and value, I will try to answer this question. Over the past few years, it has been shown that values can play a role in justifying scientific knowledge. People like Jeffrey and Betz try to take values out of science using methodological advice; while others, like Douglas, argue that values cannot and should not be excluded from science. If we accept the presence of values, there must be limits to their involvement, or we will fall to chaotic state. One of the concepts that can help us to regulate the behavior of values, is the reliability... 

    New hybrid nanocomposite of copper terephthalate MOF-graphene oxide: synthesis, characterization and application as adsorbents for toxic metal ion removal from Sungun acid mine drainage

    , Article Environmental Science and Pollution Research ; Volume 24, Issue 28 , 2017 , Pages 22353-22360 ; 09441344 (ISSN) Rahimi, E ; Mohaghegh, N ; Sharif University of Technology
    2017
    Abstract
    The application of a hybrid Cu(tpa).GO (Cu(tpa) copper terephthalate metal organic framework, GO graphene oxide) composite as a new adsorbent for the removal of toxic metal ions was reported. New hybrid nanocomposite with excellent dispersibility and stability was successfully fabricated by the simple and effective ultrasonication method. The synthesized composite was characterized by scanning electron microscopy (SEM), UV-Vis and Fourier-transform infrared (FT-IR) techniques. The characterization results concluded that the binding mechanism of the Cu(tpa) and GO was related to both packing and hydrogen bonding. For scrutinizing the sorption activity, the prepared adsorbents were assessed... 

    Estimation of Rout & Link Traffic Volume in Transportation Networks using Bluetooth & Wi-Fi Source Data

    , M.Sc. Thesis Sharif University of Technology Rahimi, Mostafa (Author) ; Shafahi, Yousef (Supervisor)
    Abstract
    Route information and link traffic volume are among the most important means that are used for analyzing transportation networks. In the past, data from Traffic Counters and Automatic Number Plate Recognition were common ways for estimating route volumes. However, the estimation of these information has improved significantly and can be done cheaper with the development of new technologies and emergence of powerful tools. One of the cheapest and highly available tools is the use of wireless networks. The most popular of such these networks are Bluetooth and Wi-Fi technologies. The use of data generated from these technologies in engineering sciences has increased due to the popularity of... 

    Numerical solution of stochastic differential equations: diffusion and jump-diffusion processes

    , Article Understanding Complex Systems ; 2019 , Pages 129-142 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Stochastic differential equations (SDE) play an important role in a range of application areas, including biology, physics, chemistry, epidemiology, mechanics, microelectronics, economics, and finance [1]. However, most SDEs, especially nonlinear SDEs, do not have analytical solutions, so that one must resort to numerical approximation schemes in order to simulate trajectories of the solutions to the given equation. The simplest effective computational method for approximation of ordinary differential equations is the Euler’s method. The Euler–Maruyama method is the analogue of the Euler’s method for ordinary differential equations for numerical simulation of the SDEs [2]. Another numerical... 

    Stochastic processes with jumps and non-vanishing higher-order kramers–moyal coefficients

    , Article Understanding Complex Systems ; 2019 , Pages 99-110 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we study stochastic processes in the presence of jump discontinuity, and discuss the meaning of non-vanishing higher-order Kramers–Moyal coefficients. We describe in details the stochastic properties of Poisson jump processes. We derive the statistical moments of the Poisson process and the Kramers–Moyal coefficients for pure Poisson jump events. Growing evidence shows that continuous stochastic modeling (white noise-driven Langevin equation) of time series of complex systems should account for the presence of discontinuous jump components [1–6]. Such time series have some distinct important characteristics, such as heavy tails and occasionally sudden large jumps.... 

    Reconstruction of stochastic dynamical equations: exemplary diffusion, jump-diffusion processes and lévy noise-driven langevin dynamics

    , Article Understanding Complex Systems ; 2019 , Pages 227-241 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we reconstruct stochastic dynamical equations with known drift and diffusion coefficients, as well as known properties of jumps, jump amplitude and jump rate from synthetic time series, sampled with time interval τ. The examples have Langevin (white noise- and Lévy noise-driven) and jump-diffusion dynamical equations. We also study the estimation of the Kramers–Moyal coefficients for “phase” dynamics that enable us to investigate the phenomenon of synchronisation in systems with interaction. © 2019, Springer Nature Switzerland AG  

    Influence of finite time step in estimating of the kramers–moyal coefficients

    , Article Understanding Complex Systems ; 2019 , Pages 191-205 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Data sampled at discrete times appear as successions of discontinuous jump events, even if the underlying trajectory is continuous. In this chapter we study finite sampling τ expansion of the Kramers-Moyal conditional moments for the Langevin and jump-diffusion dynamics. Using the expansion for the Langevin dynamics, we introduce a criterion to validate the method numerically, namely, the Pawula theorem, to judge whether the fourth-order KM moment tends to zero. The criterion is a relation between the fourth- and second-order KM conditional moments for small time lag τ [1]. © 2019, Springer Nature Switzerland AG  

    Applications and Outlook

    , Article Understanding Complex Systems ; 2019 , Pages 243-260 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    The method outlined in the Chaps. 15 – 21 has been used for revealing nonlinear deterministic and stochastic behaviors in a variety of problems, ranging from physics, to neuroscience, biology and medicine. In most cases, alternative procedures with strong emphasis on deterministic features have been only partly successful, due to their inappropriate treatment of the dynamical fluctuations [1]. In this chapter, we provide a list of the investigated phenomena using the introduced reconstruction method. In the “outlook” possible research directions for future are discussed. © 2019, Springer Nature Switzerland AG  

    How to set up stochastic equations for real world processes: Markov–einstein time scale

    , Article Understanding Complex Systems ; 2019 , Pages 165-179 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In Chaps. 16 – 21 we address a central question in the field of complex systems: Given a fluctuating (in time or space), sequentially uni- or multi-variant measured set of experimental data (even noisy data), how should one analyse the data non-parametrically, assess their underlying trends, discover the characteristics of the fluctuations, including diffusion and jump parts, and construct stochastic evolution equation for the data? © 2019, Springer Nature Switzerland AG  

    Equivalence of langevin and fokker–planck equations

    , Article Understanding Complex Systems ; 2019 , Pages 61-68 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we show the equivalence between the Langevin approach and the Fokker–Planck equation, and derive the equation for the statistical moments of the process whose dynamics is described by the Langevin equation. © 2019, Springer Nature Switzerland AG  

    The langevin equation and wiener process

    , Article Understanding Complex Systems ; 2019 , Pages 39-48 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we introduce the Langevin equation and Wiener process. All the statistical properties of Wiener process will be presented and discussed. © 2019, Springer Nature Switzerland AG  

    Introduction

    , Article Understanding Complex Systems ; 2019 , Pages 1-8 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Complex systems are composed of a large number of subsystems that may interact with each other. The typically nonlinear and multiscale interactions often lead to large-scale behaviors, which are not easily predicted from the knowledge of only the behavior of individual subsystems. © 2019, Springer Nature Switzerland AG  

    Epileptic brain dynamics

    , Article Understanding Complex Systems ; 2019 , Pages 261-271 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    As an example of the analysis and reconstruction of nonlinear stochastic time series, we consider an important medical problem, namely, epileptic brain dynamics. © 2019, Springer Nature Switzerland AG  

    The kramers–moyal coefficients of non-stationary time series and in the presence of microstructure (measurement) noise

    , Article Understanding Complex Systems ; 2019 , Pages 181-189 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Most real world time series have transient behaviours and are non-stationary. They exhibit different type of non-stationarities, such as trends, cycles, random-walking, and generally exhibit strong intermittency. Therefore local stochastic characteristics of time series, such as the drift and diffusion coefficients, as well as the jump rate and jump amplitude, will provide very important information for understanding and quantifying “real time” variability of time series. For diffusive processes the systems have a longer memory and a higher correlation time scale and, therefore, one expects the stochastic features of dynamics to change slowly. In contrast, a rapid change of dynamics with... 

    The friedrich–peinke approach to reconstruction of dynamical equation for time series: complexity in view of stochastic processes

    , Article Understanding Complex Systems ; 2019 , Pages 143-164 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we study stochastic properties of spatially- and temporally-disordered structures, such as turbulence and rough surfaces, or temporal fluctuations of given time series, in scale. Experimental observables include the field increments, such as the difference in the velocity field between two points separated by a distance r, or difference of time series in a time lag r. Therefore, the lag r can be either spatial distance or a time interval. The change of the increments’ fluctuations as a function of the scale r can then be viewed as a stochastic process in a length or time scale and can, quite often, after pioneering work by Friedrich & Peinke, be mapped onto the mathematical... 

    Distinguishing diffusive and jumpy behaviors in real-world time series

    , Article Understanding Complex Systems ; 2019 , Pages 207-213 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Jumps are discontinuous variations in time series and with large amplitude can be considered as an extreme event. We expect the higher the jump activity to cause higher uncertainty in the stochastic behaviour of measured time series. Therefore, building statistical evidence to detect real jump seems of primary importance. In addition jump events can participate in the observed non-Gaussian feature of the increments’ (ramp up and ramp down) statistics of many time series [1]. This is the reason that most of the jump detection techniques are based on threshold values for differential of time series. There is not, however, a robust method for detection and characterisation of such discontinuous... 

    Continuous stochastic processes

    , Article Understanding Complex Systems ; 2019 , Pages 31-37 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we define notions of stochastic continuity and differentiability and describe Lindeberg’s condition for continuity of stochastic Markovian trajectories. We also show that the Fokker–Planck equation describes a continuous stochastic process. Finally, we derive the stationary solutions of the Fokker–Planck equation and define potential function of dynamics. © 2019, Springer Nature Switzerland AG  

    Levy noise-driven langevin equation and its time series–based reconstruction

    , Article Understanding Complex Systems ; 2019 , Pages 87-98 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter, we introduce Lévy noise-driven Langevin and fractional Fokker–Planck equations, and derive short-time propagator of the Lévy-driven processes. Then, we provide the details of the limit theorems for the Wiener and Lévy processes. Finally, non-parametric reconstruction of the Lévy-driven Langevin dynamics from time series is described. © 2019, Springer Nature Switzerland AG  

    Jump-diffusion processes

    , Article Understanding Complex Systems ; 2019 , Pages 111-121 ; 18600832 (ISSN) Rahimi Tabar, M. R ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    In this chapter we introduce jump-diffusion processes and provide a theoretical framework that justifies the nonparametric (data-based) extraction of the parameters and functions controlling the arrival of a jump and the distribution of the jump size from the estimated conditional Kramers–Moyal moments. The method and the results are applicable to both stationary and nonstationary time series in the presence of discontinuous jump components; see Chap. 17. © 2019, Springer Nature Switzerland AG