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    Spatiotemporal registration and fusion of transthoracic echocardiography and volumetric coronary artery tree

    , Article International Journal of Computer Assisted Radiology and Surgery ; Volume 16, Issue 9 , 2021 , Pages 1493-1505 ; 18616410 (ISSN) Ghodsizad, T ; Behnam, H ; Fatemizadeh, E ; Faghihi Langroudi, T ; Bayat, F ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    Purpose: Cardiac multimodal image fusion can offer an image with various types of information in a single image. Many coronary stenosis, which are anatomically clear, are not functionally significant. The treatment of such kind of stenosis can cause irreversible effects on the patient. Thus, choosing the best treatment planning depend on anatomical and functional information is very beneficial. Methods: An algorithm for the fusion of coronary computed tomography angiography (CCTA) as an anatomical and transthoracic echocardiography (TTE) as a functional modality is presented. CCTA and TTE are temporally registered using manifold learning. A pattern search optimization algorithm, using... 

    Majorana zero-energy mode and fractal structure in fibonacci-kitaev chain

    , Article Journal of the Physical Society of Japan ; Volume 86, Issue 11 , 2017 ; 00319015 (ISSN) Ghadimi, R ; Sugimoto, T ; Tohyama, T ; Sharif University of Technology
    2017
    Abstract
    We theoretically study a Kitaev chain with a quasiperiodic potential, where the quasiperiodicity is introduced by a Fibonacci sequence. Based on an analysis of the Majorana zero-energy mode, we find the critical p-wave superconducting pairing potential separating a topological phase and a non-topological phase. The topological phase diagram with respect to Fibonacci potentials follow a self-similar fractal structure characterized by the box-counting dimension, which is an example of the interplay of fractal and topology like the Hofstadter's butterfly in quantum Hall insulators. © 2017 The Physical Society of Japan  

    Accelerating federated edge learning

    , Article IEEE Communications Letters ; Volume 25, Issue 10 , 2021 , Pages 3282-3286 ; 10897798 (ISSN) Nguyen, T. D ; Balef, A. R ; Dinh, C. T ; Tran, N. H ; Ngo, D. T ; Anh Le, T ; Vo, P. L ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    Transferring large models in federated learning (FL) networks is often hindered by clients' limited bandwidth. We propose $ extsf {FedAA}$ , an FL algorithm which achieves fast convergence by exploiting the regularized Anderson acceleration (AA) on the global level. First, we demonstrate that FL can benefit from acceleration methods in numerical analysis. Second, $ extsf {FedAA}$ improves the convergence rate for quadratic losses and improves the empirical performance for smooth and strongly convex objectives, compared to FedAvg, an FL algorithm using gradient descent (GD) local updates. Experimental results demonstrate that employing AA can significantly improve the performance of FedAvg,... 

    Study of the effect of thermal dispersion on internal natural convection in porous media using fourier series

    , Article Transport in Porous Media ; Volume 131, Issue 2 , 2020 , Pages 537-568 Fahs, M ; Graf, T ; Tran, T. V ; Ataie Ashtiani, B ; Simmons, C. T ; Younes, A ; Sharif University of Technology
    Springer  2020
    Abstract
    Natural convection in a porous enclosure in the presence of thermal dispersion is investigated. The Fourier–Galerkin (FG) spectral element method is adapted to solve the coupled equations of Darcy’s flow and heat transfer with a full velocity-dependent dispersion tensor, employing the stream function formulation. A sound implementation of the FG method is developed to obtain accurate solutions within affordable computational costs. In the spectral space, the stream function is expressed analytically in terms of temperature, and the spectral system is solved using temperature as the primary unknown. The FG method is compared to finite element solutions obtained using an in-house code... 

    A probabilistic artificial neural network-based procedure for variance change point estimation

    , Article Soft Computing ; Vol. 19, issue. 3 , May , 2014 , pp. 691-700 ; ISSN: 14327643 Amiri, A ; Niaki, S. T. A ; Moghadam, A. T ; Sharif University of Technology
    2014
    Abstract
    Control charts are useful tools of monitoring quality characteristics. One of the problems of employing a control chart is that the time it alarms is not synchronic with the time when assignable cause manifests itself in the process. This makes difficult to search and find assignable causes. Knowing the real time of manifestation of assignable cause (change point) helps to find assignable cause(s) sooner and eases corrective actions to be taken. In this paper, a probabilistic neural network (PNN)-based procedure was developed to estimate the variance change point of a normally distributed quality characteristic. The PNN was selected based on trial and error among different types of... 

    Two studies of framework-usage templates extracted from dynamic traces

    , Article IEEE Transactions on Software Engineering ; Volume 38, Issue 6 , 2012 , Pages 1464-1487 ; 00985589 (ISSN) Heydarnoori, A ; Czarnecki, K ; Binder, W ; Bartolomei, T. T ; Sharif University of Technology
    2012
    Abstract
    Object-oriented frameworks are widely used to develop new applications. They provide reusable concepts that are instantiated in application code through potentially complex implementation steps such as subclassing, implementing interfaces, and calling framework operations. Unfortunately, many modern frameworks are difficult to use because of their large and complex APIs and frequently incomplete user documentation. To cope with these problems, developers often use existing framework applications as a guide. However, locating concept implementations in those sample applications is typically challenging due to code tangling and scattering. To address this challenge, we introduce the notion of... 

    On the throughput and outage probability of multi-relay networks with imperfect power amplifiers

    , Article IEEE Transactions on Wireless Communications ; Volume 14, Issue 9 , May , 2015 , Pages 4994-5008 ; 15361276 (ISSN) Makki, B ; Svensson, T ; Eriksson, T ; Nasiri Kenari, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    This paper studies the energy-limited performance of multi-relay networks. Taking the properties of the power amplifiers (PAs) into account, we derive closed-form expressions for the optimal power allocation, the outage probability and the throughput in the cases with a sum consumed energy constraint. Moreover, we analyze the diversity and the multiplexing gains of the PA-aware systems. Finally, we investigate the performance of large-scale multi-relay networks and develop efficient multi-relay systems with low cooperation overhead. The numerical and the analytical results show that the inefficiency of the PAs affects the outage probability and the throughput of the multi-relay systems... 

    Online jointly estimation of hysteretic structures using the combination of central difference Kalman filter and Robbins–Monro technique

    , Article JVC/Journal of Vibration and Control ; 2020 Amini Tehrani, H ; Bakhshi, A ; Yang, T. T. Y ; Sharif University of Technology
    SAGE Publications Inc  2020
    Abstract
    Rapid assessment of structural safety and performance right after the occurrence of significant earthquake shaking is crucial for building owners and decision-makers to make informed risk management decisions. Hence, it is vital to develop online and pseudo-online health monitoring methods to quantify the health of the building right after significant earthquake shaking. Many Bayesian inference–based methods have been developed in the past which allow the users to estimate the unknown states and parameters. However, one of the most challenging part of the Bayesian inference–based methods is the determination of the parameter noise covariance matrix. It is especially difficult when the number... 

    Online probabilistic model class selection and joint estimation of structures for post-disaster monitoring

    , Article JVC/Journal of Vibration and Control ; 2020 Amini Tehrani, H ; Bakhshi, A ; Yang, T. T. Y ; Sharif University of Technology
    SAGE Publications Inc  2020
    Abstract
    Online selection of the appropriate model and identifying its parameters based on measured vibrational data are among the challenging issues in dynamic system identification. After a severe earthquake, quick monitoring and assessment of structural health status play a crucial role in effective critical risk management for the building owners and decision-makers. The Bayesian multiple modeling approach is a suitable tool for optimal model class selection, which is used in this article mainly for improving data fitting precision, decreasing dimensions of structural unknown vector through removing unnecessary parameters, detecting the occurrence and type of predominant phenomenon related to... 

    Online probabilistic model class selection and joint estimation of structures for post-disaster monitoring

    , Article JVC/Journal of Vibration and Control ; Volume 27, Issue 15-16 , 2021 , Pages 1860-1878 ; 10775463 (ISSN) Amini Tehrani, H ; Bakhshi, A ; Yang, T. T .Y ; Sharif University of Technology
    SAGE Publications Inc  2021
    Abstract
    Online selection of the appropriate model and identifying its parameters based on measured vibrational data are among the challenging issues in dynamic system identification. After a severe earthquake, quick monitoring and assessment of structural health status play a crucial role in effective critical risk management for the building owners and decision-makers. The Bayesian multiple modeling approach is a suitable tool for optimal model class selection, which is used in this article mainly for improving data fitting precision, decreasing dimensions of structural unknown vector through removing unnecessary parameters, detecting the occurrence and type of predominant phenomenon related to... 

    Online jointly estimation of hysteretic structures using the combination of central difference kalman filter and robbins–monro technique

    , Article JVC/Journal of Vibration and Control ; Volume 27, Issue 1-2 , 2021 , Pages 234-247 ; 10775463 (ISSN) Amini Tehrani, H ; Bakhshi, A ; Yang, T. T. Y ; Sharif University of Technology
    SAGE Publications Inc  2021
    Abstract
    Rapid assessment of structural safety and performance right after the occurrence of significant earthquake shaking is crucial for building owners and decision-makers to make informed risk management decisions. Hence, it is vital to develop online and pseudo-online health monitoring methods to quantify the health of the building right after significant earthquake shaking. Many Bayesian inference–based methods have been developed in the past which allow the users to estimate the unknown states and parameters. However, one of the most challenging part of the Bayesian inference–based methods is the determination of the parameter noise covariance matrix. It is especially difficult when the number... 

    Noninvasive estimation of tissue temperature via high-resolution spectral analysis techniques

    , Article IEEE Transactions on Biomedical Engineering ; Volume 52, Issue 2 , 2005 , Pages 221-228 ; 00189294 (ISSN) Nasiri Amini, A ; Ebbini, E. S ; Georgiou, T. T ; Sharif University of Technology
    2005
    Abstract
    We address the noninvasive temperature estimation from pulse-echo radio frequency signals from standard diagnostic ultrasound imaging equipment. In particular, we investigate the use of a high-resolution spectral estimation method for tracking frequency shifts at two or more harmonic frequencies associated with temperature change. The new approach, employing generalized second-order statistics, is shown to produce superior frequency shift estimates when compared to conventional high-resolution spectral estimation methods Seip and Ebbini (1995). Furthermore, temperature estimates from the new algorithm are compared with results from the more commonly used echo shift method described in Simon... 

    Vulnerability modeling of cryptographic hardware to power analysis attacks

    , Article Integration, the VLSI Journal ; Volume 42, Issue 4 , 2009 , Pages 468-478 ; 01679260 (ISSN) Moradi, A ; Salmasizadeh, M ; Manzuri Shalmani, M. T ; Eisenbarth, T ; Sharif University of Technology
    2009
    Abstract
    Designers and manufacturers of cryptographic devices are always worried about the vulnerability of their implementations in the presence of power analysis attacks. This article can be categorized into two parts. In the first part, two parameters are proposed to improve the accuracy of the latest hypothetical power consumption model, so-called toggle-count model, which is used in power analysis attacks. Comparison between our proposed model and the toggle-count model demonstrates a great advance, i.e., 16%, in the similarity of hypothetical power values to the corresponding values obtained by an analog simulation. It is supposed that the attacker would be able to build such an accurate power... 

    Partial discharges pattern recognition of transformer defect model by LBP & HOG features

    , Article IEEE Transactions on Power Delivery ; 2018 ; 08858977 (ISSN) Firuzi, K ; Vakilian, M ; Phung, B. T ; Blackburn, T. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Partial discharge (PD) measurement and identification have great importance to condition monitoring of power transformers. In this paper a new method for recognition of single and multi-source of PD based on extraction of high level image features have been introduced. A database, involving 365 samples of phase-resolved PD (PRPD) data, is developed by measurement carried out on transformer artificial defect models (having different sizes of defect) under a specific applied voltage, to be used for proposed algorithm validation. In the first step, each set of PRPD data is converted into grayscale images to represent different PD defects. Two “image feature extraction” methods, the Local Binary... 

    A Hybrid transformer pd monitoring method using simultaneous iec60270 and rf data

    , Article IEEE Transactions on Power Delivery ; Volume 34, Issue 4 , 2019 , Pages 1374-1382 ; 08858977 (ISSN) Firuzi, K ; Vakilian, M ; Phung, B. T ; Blackburn, T. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Transformers are the key component in power system transmission and distribution networks. Condition-based maintenance will increase their expected life, and online monitoring is essential to ensure operation reliability. In this paper, a new approach to transformer online monitoring is provided based on partial discharge (PD) measurement. Simultaneous measurements of PD using IEC60270 and radio frequency (RF) techniques are employed to explore new features that can be used to distinguish between internal PDs and external interference, as well as among different internal PD sources. Stream clustering based on the density grid method with only a few features required is used to categorize... 

    Partial discharges pattern recognition of transformer defect model by LBP & HOG features

    , Article IEEE Transactions on Power Delivery ; Volume 34, Issue 2 , 2019 , Pages 542-550 ; 08858977 (ISSN) Firuzi, K ; Vakilian, M ; Phung, B. T ; Blackburn, T. R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Partial discharge (PD) measurement and identification have great importance to condition monitoring of power transformers. In this paper, a new method for recognition of single and multi-source of PD based on extraction of high level image features has been introduced. A database, involving 365 samples of phase-resolved PD (PRPD) data, is developed by measurement carried out on transformer artificial defect models (having different sizes of defect) under a specific applied voltage, to be used for proposed algorithm validation. In the first step, each set of PRPD data is converted into grayscale images to represent different PD defects. Two 'image feature extraction' methods, the Local Binary... 

    Unreliability of mutual information as a measure for variations in total correlations

    , Article Physical Review A ; Volume 101, Issue 4 , 2020 Alipour, S ; Tuohino, S ; Rezakhani, A. T ; Ala-Nissila, T ; Sharif University of Technology
    American Physical Society  2020
    Abstract
    Correlations disguised in various forms underlie a host of important phenomena in classical and quantum systems, such as information and energy exchanges. The quantum mutual information and the norm of the correlation matrix are both considered as proper measures of total correlations. We demonstrate that, when applied to the same system, these two measures can actually show significantly different behavior except at least in two limiting cases: when there are no correlations and when there is maximal quantum entanglement. We further quantify the discrepancy by providing analytic formulas for time derivatives of the measures for an interacting bipartite system evolving unitarily. We argue... 

    Cohen–macaulayness of a class of graphs versus the class of their complements

    , Article Discrete Mathematics ; Volume 344, Issue 10 , 2021 ; 0012365X (ISSN) Ashitha, T ; Asir, T ; Hoang, D. T ; Pournaki, M. R ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    Let n≥2 be an integer. The graph G(n) is obtained by letting all the elements of {0,…,n−1} to be the vertices and defining distinct vertices x and y to be adjacent if and only if gcd⁡(x+y,n)=1. In this paper, well-coveredness, Cohen–Macaulayness, vertex-decomposability and Gorensteinness of these graphs and their complements are characterized. These characterizations provide large classes of Cohen–Macaulay and non Cohen–Macaulay graphs. © 2021 Elsevier B.V  

    Direct introduction of semicon layers in XLPE cable model

    , Article 2006 International Conference on Power System Technology, POWERCON2006, Chongqing, 22 October 2006 through 26 October 2006 ; 2006 ; 1424401119 (ISBN); 9781424401116 (ISBN) Hasheminezhad, M ; Vakilian, M ; Blackburn, T. R ; Phung, B. T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    Abstract
    Detection and location of any partial discharge signal requires an accurate frequency dependent cable model to correctly simulate the P.D. signal attenuation during its propagation in the cable. This model should be capable of simulating the semiconducting layers which have significant effects on P.D. signal attenuation and its propagation velocity. There is a substantial need for improvements in the flexibility of transient cable model through direct introduction of the two semiconducting layers in the cable model. This can be employed, in the next step to develop a 3 phase cable model for ATP. This paper has derived an impedance formula for the semiconducting layers. The propagation... 

    Correlation-enabled energy exchange in quantum systems without external driving

    , Article Physical Review A ; Volume 105, Issue 2 , 2022 ; 24699926 (ISSN) Pyhäranta, T ; Alipour, S ; Rezakhani, A. T ; Ala Nissila, T ; Sharif University of Technology
    American Physical Society  2022
    Abstract
    We study the role of correlation in mechanisms of energy exchange between an interacting bipartite quantum system and its environment by decomposing the energy of the system to local and correlation-related contributions. When the system Hamiltonian is time independent, no external work is performed. In this case, energy exchange between the system and its environment occurs only due to the change in the state of the system. We investigate the possibility of a special case where the energy exchange with the environment occurs exclusively due to changes in the correlation between the constituent parts of the bipartite system, while their local energies remain constant. We find sufficient...