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    Power allocation of sensor transmission for remote estimation over an unknown gilbert-elliott channel

    , Article 18th European Control Conference, ECC 2020, 12 May 2020 through 15 May 2020 ; 2020 , Pages 1461-1467 Farjam, T ; Fardno, F ; Charalambous, T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    In this paper, we consider the problem of scheduling the power of a sensor when transmitting over an unknown Gilbert-Elliott (GE) channel for remote state estimation. The sensor supports two power modes, namely low power and high power, which are to be selected for transmission over the channel in order to minimize a cost on the error covariance, while satisfying the energy constraints. The remote estimator provides error-free acknowledgement/negative-acknowledgement (ACK/NACK) messages to the sensor only when low power is utilized. We first consider the Partially Observable Markov Decision Process (POMDP) problem for the case of known GE channels and derive conditions for optimality of a... 

    Modeling and Optimization of Different Powertrain Configurations for a Specific Electric Vehicle

    , M.Sc. Thesis Sharif University of Technology Farjam, Tahmoores (Author) ; Saadat Foumani, Mahmoud (Supervisor)
    Abstract
    In recent years passenger cars have been known as the main source of air pollution in urban areas. Despite all the research and efforts in minimizing the fuel consumption and emissions of internal combustion engines (ICE), this is merely a temporary solution. The permanent solution to overcome these disavantages is the use of electric vehicles (EV). The main downside of using electric vehicles is their short driving range. Multi-speed transmissions can be adopted to overcome this problem. Continuously variable transmissions (CVT) and infinitely variable transmissions (IVT) have been proven to enhance fuel economy in ICE vehicles and a great deal of research is being conducted to maximize... 

    Optimization of multiple transmission layouts for minimal energy consumption of a battery electric vehicle

    , Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2382-2393 ; 10263098 (ISSN) Farjam, T ; Saadat Foumani , M ; Delkhosh, M ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    Battery Electric Vehicles (BEVs) are a promising solution for reducing the impacts of passenger vehicles on the environment. However, their driving range is restricted due to the limitations of battery technologies. This range can be extended by adoption of multiple-speed transmissions. Most of the comparisons in the related studies are based on non-optimal designs or limited to modal driving cycles. Furthermore, the impact of Power-Split. Continuously Variable Transmission (PS-CVT) layout with type III power How on the power consumption of BEVs has never been examined. In this paper, single-, two-, and three-speed transmissions along with PS-C'VTs with type I and III power flows are... 

    Optimization of multiple transmission layouts for minimal energy consumption of a battery electric vehicle

    , Article Scientia Iranica ; Volume 26, Issue 4A , 2019 , Pages 2382-2393 ; 10263098 (ISSN) Farjam, T ; Foumani, M. S ; Delkhosh, M ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    Battery Electric Vehicles (BEVs) are a promising solution for reducing the impacts of passenger vehicles on the environment. However, their driving range is restricted due to the limitations of battery technologies. This range can be extended by adoption of multiple-speed transmissions. Most of the comparisons in the related studies are based on non-optimal designs or limited to modal driving cycles. Furthermore, the impact of Power-Split. Continuously Variable Transmission (PS-CVT) layout with type III power How on the power consumption of BEVs has never been examined. In this paper, single-, two-, and three-speed transmissions along with PS-C'VTs with type I and III power flows are... 

    Direct observation of a dispersionless impurity band in hydrogenated graphene

    , Article Physical Review B - Condensed Matter and Materials Physics ; Volume 83, Issue 16 , 2011 ; 10980121 (ISSN) Haberer, D ; Petaccia, L ; Farjam, M ; Taioli, S ; Jafari, S. A ; Nefedov, A ; Zhang, W ; Calliari, L ; Scarduelli, G ; Dora, B ; Vyalikh, D. V ; Pichler, T ; Wöll, C ; Alfè, D ; Simonucci, S ; Dresselhaus, M. S ; Knupfer, M ; Büchner, B ; Grüneis, A ; Sharif University of Technology
    2011
    Abstract
    We show with angle-resolved photoemission spectroscopy that a new energy band appears in the electronic structure of electron-doped hydrogenated monolayer graphene (H-graphene). Its occupation can be controlled with the hydrogen amount and allows for tuning of graphene's doping level. Our calculations of the electronic structure of H-graphene suggest that this state is largely composed of hydrogen 1s orbitals and remains extended for low H coverages despite the random chemisorption of H. Further evidence for the existence of a hydrogen state is provided by x-ray absorption studies of undoped H-graphene which are clearly showing the emergence of an additional state in the vicinity of the π*... 

    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... 

    Electronic properties of hydrogenated quasi-free-standing graphene

    , Article Physica Status Solidi (B) Basic Research ; Volume 248, Issue 11 , OCT , 2011 , Pages 2639-2643 ; 03701972 (ISSN) Haberer, D ; Petaccia, L ; Wang, Y ; Quian, H ; Farjam, M ; Jafari, S. A ; Sachdev, H ; Federov, A. V ; Usachov, D ; Vyalikh, D. V ; Liu, X ; Vilkov, O ; Adamchuk, V. K ; Irle, S ; Knupfer, M ; Büchner, B ; Grüneis, A ; Sharif University of Technology
    2011
    Abstract
    Tailoring the electronic properties of graphene is of fundamental interest regarding its application in electronic devices. One of the key strategies is chemical functionalization which modifies the p-electron system and thus can induce band gaps. However, in order to control the degree of functionalization it is crucial to know the exact amount of the chemisorbed species. We show with angle-resolved photoemission spectroscopy (ARPES) the formation of a band gap in graphene and estimate the hydrogen coverage from the scattering rate. Using X-ray photoemission spectroscopy (XPS) we identify the chemical environments in hydrogenated graphene and determine the total hydrogen to carbon... 

    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...