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    Incorporating a novel confidence scoring method in a Persian spoken dialogue system

    , Article SPA 2011 - Signal Processing: Algorithms, Architectures, Arrangements, and Applications - Conference Proceedings, 29 September 2011 through 30 September 2011, Poznan ; September , 2011 , Pages 74-78 ; 9781457714863 (ISBN) Sakhaee, E ; Sameti, H ; Babaali, B ; Sharif University of Technology
    2011
    Abstract
    Reliability assessment of phonemes, syllabi, words, concepts or utterances has become the key feature of Automatic Speech Recognition (ASR) engines in order to make a decision to accept or reject a hypothesis. In this paper, we propose utterance-level confidence annotation based on combination of features extracted from multiple knowledge sources in Persian language. The experiment was conducted first to examine the performance of individual features, then to combine them using statistical data analysis and density estimation methods to assign a confidence score to utterances. Using the data collected from a Persian spoken dialogue system, we show that combining features from independent... 

    Integration of clustering analysis and reward/penalty mechanisms for regulating service reliability in distribution systems

    , Article IET Generation, Transmission and Distribution ; Volume 5, Issue 11 , 2011 , Pages 1192-1200 ; 17518687 (ISSN) Mohammadnezhad Shourkaei, H ; Fotuhi Firuzabad, M ; Billinton, R ; Sharif University of Technology
    Abstract
    This study proposes an approach for improving service reliability in the distribution network based on establishing competition among electric distribution utilities. The idea behind this approach is to categorise the utilities and compare the performance of utilities located in one cluster with the other members of the same cluster. The reward/penalty mechanism (RPM) as a quality regulating instrument is designed for each cluster and used to penalise the utilities with a performance worse than the benchmark and to reward them for providing a performance better than the benchmark. Based on the RPM, utilities located in one cluster compete to make more profit by serving customers in better... 

    Fast reliability analysis method for sequential logic circuits

    , Article Proceedings - ICSEng 2011: International Conference on Systems Engineering, 16 August 2011 through 18 August 2011, Las Vegas, NV ; 2011 , Pages 352-356 ; 9780769544953 (ISBN) Mohammadi, K ; Jahanirad, H ; Attarsharghi, P ; Sharif University of Technology
    2011
    Abstract
    Reliability analysis of combinational logic circuits using error probabilities methods, such as PTM, has been widely developed and used in literature. However, using these methods for reliability analysis of sequential logic circuits will lead to inaccurate results, because of existence of loops in their architecture. In this paper a new method is proposed based on converting the sequential circuit to a secondary combinational circuit and applying an iterative reliability analysis to the resulting configuration. Experimental results demonstrate good accuracy levels for this method  

    FEM analysis of single grit chip formation in creep-feed grinding of Inconel 718 superalloy

    , Article Advanced Materials Research, 18 September 2011 through 21 September 2011, Stuttgart ; Volume 325 , 2011 , Pages 128-133 ; 10226680 (ISSN) ; 9783037852316 (ISBN) Zahedi, A ; Akbari, J ; Sharif University of Technology
    2011
    Abstract
    Recent advances in materials science have necessitated the development and understanding of manufacturing processes for safe and repeatable utilization. Grinding is shown to be a promising material removal process especially for brittle and hard to cut materials such as superalloys. Grinding has always been associated with analysis and modeling complications regarding its nature which has limited its extension and reliability of use. The first step in analysis of grinding is considering the action of a single abrasive grit on workpiece surface. In this work the action of a single CBN abrasive grit in creep-feed grinding process of Inconel 718 superalloy is modeled and analyzed using a 3D FEM... 

    Probabilistic worth assessment of distributed static series compensators

    , Article IEEE Transactions on Power Delivery ; Volume 26, Issue 3 , July , 2011 , Pages 1734-1743 ; 08858977 (ISSN) Dorostkar Ghamsari, M ; Fotuhi Firuzabad, M ; Aminifar, F ; Sharif University of Technology
    2011
    Abstract
    The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a... 

    Numerical modeling of incline plate LiBr absorber

    , Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 47, Issue 3 , November , 2011 , Pages 259-267 ; 09477411 (ISSN) Karami, S ; Farhanieh, B ; Sharif University of Technology
    2011
    Abstract
    Among major components of LiBr-H 2O absorption chillers is the absorber, which has a direct effect on the chillier size and whose characteristics have significant effects on the overall efficiency of absorption machines. In this article, heat and mass transfer process in absorption of refrigerant vapor into a lithium bromide solution of water-cooled incline plate absorber in the Reynolds number range of 5

    Integration of large-scale wind farm projects including system reliability analysis

    , Article IET Renewable Power Generation ; Volume 5, Issue 1 , 2011 , Pages 89-98 ; 17521416 (ISSN) Salehi Dobakhshari, A ; Fotuhi-Firuzabad, M ; Sharif University of Technology
    Abstract
    This study intends to develop a comprehensive procedure for evaluating locational value of a wind farm project incorporating reduction in transmission system losses, load delivery point interruption cost and operating cost of generating units. The energy extracted from the wind farm in normal operation condition is considered to replace the energy from fossil-fueled conventional units. In addition, composite system reliability analysis in the presence of wind power is carried out to evaluate total costs associated with curtailed energy at different load points as well as generation of generating units in contingency conditions. System reliability analysis related to large-scale wind farms,... 

    Low energy yet reliable data communication scheme for network-on-chip

    , Article IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems ; Volume 34, Issue 12 , 2015 , Pages 1892-1904 ; 02780070 (ISSN) Jafarzadeh, N ; Palesi, M ; Eskandari, S ; Hessabi, S ; Afzali-Kusha, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    In this paper, a low energy yet reliable communication scheme for network-on-chip is suggested. To reduce the communication energy consumption, we invoke low-swing signals for transmitting data, as well as data encoding techniques, for minimizing both self and coupling switching capacitance activity factors. To maintain the communication reliability of communication at low-voltage swing, an error control coding (ECC) technique is exploited. The decision about end-To-end or hop-To-hop ECC schemes and the proper number of detectable errors are determined through high-level mathematical analysis on the energy and reliability characteristics of the techniques. Based on the analysis, the extended... 

    Assessment of Existing Jacket Type Offshore Platform against Environmental Wave Loading Utilizing Theory of Reliability

    , M.Sc. Thesis Sharif University of Technology Bagheri Baygi, Vahid (Author) ; Golafshani, Ali Akbar (Supervisor)
    Abstract
    Assessment of existing jacket type offshore platform against environmental wave loading hazard is the central component of this work. Two general approaches exist in this context, deterministic and probabilistic assessment. In this study, a new probabilistic method (reliability analysis) to assess offshore structures under environmental loading (extreme wave) is introduced. Before describing this approach, several necessary elements such as collapse analysis, sampling methods and wave hazard analysis should be investigated. First of all, deterministic assessment of SPD2 platform located in Persian Gulf, which is the case study considered in this dissertation, is conducted utilizing... 

    An Approximation Method for Reliability Analysis of Standby Systems

    , M.Sc. Thesis Sharif University of Technology Rezaieha Javadi Tanha, Bahram (Author) ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
    Abstract
    Analyzing reliability of large cold-standby systems has been a complicated and time-consuming task, especially for systems with components having non-exponential time-to-failure distributions. In this research, an approximation model, which is based on the central limit theorem, is presented for the reliability analysis of binary cold-standby systems whit non-identical components. The proposed model can estimate the reliability of large cold-standby systems with binary-state components having arbitrary time-to-failure distributions in an efficient and easy way. The accuracy and efficiency of the proposed method are illustrated using several different types of distributions, such as... 

    FiWi enhanced LTE-A HetNets with unreliable fiber backhaul sharing and WiFi offloading

    , Article Proceedings - IEEE INFOCOM, 26 April 2015 through 1 May 2015 ; Volume 26 , 2015 , Pages 1275-1283 ; 0743166X (ISSN) ; 9781479983810 (ISBN) Beyranvand, H ; Levesque, M ; Maier, M ; Salehi, J. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    To cope with the unprecedented growth of mobile data traffic, we investigate the performance gains obtained from unifying coverage-centric 4G mobile networks and capacity-centric fiber-wireless (FiWi) broadband access networks based on data-centric Ethernet technologies with resulting fiber backhaul sharing and WiFi offloading capabilities. Despite recent progress on backhaul-aware 4G studies with capacity-limited backhaul links, the performance-limiting impact of backhaul latency and reliability has not been examined in sufficient detail previously. In this paper, we evaluate the maximum aggregate throughput, offloading efficiency, and in particular the delay performance of FiWi enhanced... 

    Benefits of real-time monitoring to distribution systems: dynamic thermal rating

    , Article IEEE Transactions on Smart Grid ; Volume 6, Issue 4 , 2015 , Pages 2023-2031 ; 19493053 (ISSN) Safdarian, A ; Degefa, M. Z ; Fotuhi Firuzabad, M ; Lehtonen, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    With anticipated proliferation of electric vehicles and distributed generations in near future, dynamic thermal rating (DTR) as a tool for unlocking network capacities, is becoming critical for distribution network operators. DTR is gaining a great and still growing focus of attention in today's power industries. However, potential benefits of DTR, although have been envisioned to be significant, have not yet been studied quantitatively. This paper intends to comprehensively assess the potential impacts of DTR on the performance of a realistic Finnish distribution network. For doing so, first a step-by-step procedure is devised. Then, weather data and loading information of circuits in the... 

    Developing a stochastic framework to determine the static reserve requirements of high-wind penetrated power systems

    , Article Journal of Intelligent and Fuzzy Systems ; Volume 29, Issue 5 , 2015 , Pages 2039-2046 ; 10641246 (ISSN) Riahinia, S ; Abbaspour, A ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
    IOS Press  2015
    Abstract
    Operational and planning studies of high-wind penetrated power systems have well come to the light as a major concern of future energy systems. This paper focuses on the procedure of determining required static reserve of the high-wind penetrated power systems which has not been well accompanied by comprehensive analysis and proper modeling tools. To reach this goal, first, a probabilistic algorithm has been proposed to effectively model the variations in output generation of wind turbines. In this algorithm, the fuzzy c-means clustering method (FCM) is exploited as an efficient as well as robust clustering method to find the multi-state model of wind turbines output generation. Based on... 

    Application of Endurance Time Method in Optimum Seismic Design of Structures Based on Life Cycle Cost

    , Ph.D. Dissertation Sharif University of Technology Charkhtab Basim, Mohammad (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)
    Abstract
    In recent decades, large economic losses and social impacts following earthquakes and hurricanes have revealed the need for improved design criteria intended to reduce consequences including economic impacts to an acceptable level along with life protection. So, it is tried to express the expected performance of structures as financial and social criteria. Any assessment on earthquake consequences requires estimations of structural responses to seismic excitations. Endurance Time (ET) method as a dynamic procedure requiring reasonably reduced computational effort compared to other common time-history based procedures, is used to estimate the response of the structure in all levels of hazard... 

    Design and evaluation of a novel triaxial isometric trunk muscle strength measurement system

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 223, Issue 6 , 2015 , Pages 755-766 ; 09544119 (ISSN) Azghani, M. R ; Farahmand, F ; Meghdari, A ; Vossoughi, G ; Parnianpour, M ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Abstract
    Maximal strength measurements of the trunk have been used to evaluate the maximum functional capacity of muscles and the potential mechanical overload or overuse of the lumbar spine tissues in order to estimate the risk of developing musculoskeletal injuries. A new triaxial isometric trunk strength measurement system was designed and developed in the present study, and its reliability and performance was investigated. The system consisted of three main revolute joints, equipped with torque sensors, which intersect at L5 - S1 and adjustment facilities to fit the body anthropometry and to accommodate both symmetric and asymmetric postures in both seated and standing positions. The dynamics of... 

    New considerations in modern protection system quantitative reliability assessment

    , Article IEEE Transactions on Power Delivery ; Volume 25, Issue 4 , September , 2010 , Pages 2213-2222 ; 08858977 (ISSN) Etemadi, A. H ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2010
    Abstract
    Protective relay technologies have evolved from single-function electromechanical and static relays to modern multifunction digital relays over the past few years. Protection systems play a vital role in maintaining a desirable level of reliability in power systems. Thus, their own reliability should be evaluated and any cause of their malfunction should be fully comprehended. In this paper, a new reliability model is proposed that associates protection system failures to four main causes: 1) relay hardware, 2) relay software, 3) ancillary equipment, and 4) human error. In addition, this model can take other aspects of the protection system into consideration, such as human error during... 

    Reliability modeling of PMUs using fuzzy sets

    , Article IEEE Transactions on Power Delivery ; Volume 25, Issue 4 , August , 2010 , Pages 2384-2391 ; 08858977 (ISSN) Aminifar, F ; Bagheri Shouraki, S ; Fotuhi Firuzabad, M ; Shahidehpour, M ; Sharif University of Technology
    2010
    Abstract
    Probabilistic analyses of a wide-area measurement system (WAMS) would require equivalent reliability models for its components which include phasor measurement units (PMUs). In this paper, the reliability modeling of PMU is proposed and the proposed model is extended to consider options for the PMU hardware. The Markov process is employed to analyze the proposed model and to present an equivalent two-state model of PMUs. Reliability parameters of PMU are estimated with major difficulties associated with limited and uncertain data. In this paper, uncertainties are taken into account to achieve more realistic estimates of PMU characteristics. Fuzzy sets along with reliability analyses and... 

    Failure Modes and Effects Analysis (FMEA) for wind turbines

    , Article International Journal of Electrical Power and Energy Systems ; Volume 32, Issue 7 , 2010 , Pages 817-824 ; 01420615 (ISSN) Arabian Hoseynabadi, H ; Oraee, H ; Tavner, P. J ; Sharif University of Technology
    2010
    Abstract
    The Failure Modes and Effects Analysis (FMEA) method has been used to study the reliability of many different power generation systems. This paper now applies that method to a wind turbine (WT) system using a proprietary software reliability analysis tool. Comparison is made between the quantitative results of an FMEA and reliability field data from real wind turbine systems and their assemblies. These results are discussed to establish relationships which are useful for future wind turbine designs. The main system studied is an existing design 2 MW wind turbine with a Doubly Fed Induction Generator (DFIG), which is then compared with a hypothetical wind turbine system using the Brushless... 

    Optimal reserve capacity allocation with consideration of customer reliability requirements

    , Article Energy ; Volume 35, Issue 9 , 2010 , Pages 3883-3890 ; 03605442 (ISSN) Najafi, M ; Ehsan, M ; Fotuhi Firuzabad, M ; Akhavein, A ; Afshar, K ; Sharif University of Technology
    2010
    Abstract
    An algorithm for determining optimal reserve capacity in a power market is presented in this paper. Optimization process in the proposed algorithm is based on the cost-benefit trade off. Market clearance is executed with consideration of uncertainties of power system components in an aggregated environment. It is assumed that both generating units and interruptible loads participate in the reserve market. In addition, customers' reliability requirements are considered as constraints for decision making process of ISO. The rendered method considers random outages of generating units and transmission lines and determined outage of interruptible loads and employs Monte Carlo Simulation (MCS)... 

    Reliability of recurrence quantification analysis measures of the center of pressure during standing in individuals with musculoskeletal disorders

    , Article Medical Engineering and Physics ; Volume 32, Issue 7 , 2010 , Pages 808-812 ; 13504533 (ISSN) Mazaheri, M ; Negahban, H ; Salavati, M ; Sanjari, M. A ; Parnianpour, M ; Sharif University of Technology
    2010
    Abstract
    Although the application of nonlinear tools including recurrence quantification analysis (RQA) has increasingly grown in the recent years especially in balance-disordered populations, there have been few studies which determine their measurement properties. Therefore, a methodological study was performed to estimate the intersession and intrasession reliability of some dynamic features provided by RQA for nonlinear analysis of center of pressure (COP) signals recorded during quiet standing in a sample of patients with musculoskeletal disorders (MSDs) including low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI). The subjects completed postural...