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Total 131 records

    Fault effect analysis of the exhaust manifold leakage for a turbocharged spark ignition engine

    , Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Vol. 228, issue. 8 , 2014 , pp. 970-984 ; ISSN: 09544070 Salehi, R ; Vossoughi, G ; Alasty, A ; Sharif University of Technology
    Abstract
    Fault monitoring in internal-combustion engines is crucial for keeping the vehicle performance within the acceptable standards of emission levels and drivers' demands. This paper analyses how a vehicle's performance and engine variables are affected by a leakage fault in the exhaust manifold. The threshold leakage that causes the vehicle to exceed the emission standards is determined for a class M1 vehicle tested on a chassis dynamometer over the New European Driving Cycle. It is shown that, when a leakage of 6 mm diameter on the exhaust manifold is introduced, the vehicle emissions exceed those specified in the European 2013 on-board diagnostics standard. In addition, the effects of the... 

    On-line fault detection and isolation (FDI) for the exhaust path of a turbocharged SI engine

    , Article ASME 2013 Dynamic Systems and Control Conference, DSCC 2013 ; Vol. 1 , 2013 ; ISBN: 9780791856123 Salehi, R ; Shahbakhti M ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    Abstract
    Detection and isolation of faults in the exhaust gas path of a turbocharged spark ignition (SI) engine is an essential part of the engine control unit (ECU) strategies to minimize exhaust emission and ensure safe operation of a turbocharger. This paper proposes a novel physics-based strategy to detect and isolate an exhaust manifold leakage and a closed-stuck wastegate fault. The strategy is based on a globally optimal parameter estimation algorithm which detects an effective hole area in the exhaust manifold. The estimation algorithm requires prediction of the exhaust manifold's input and output flows. The input flow is predicted by a nonlinear Luenberger observer which is analytically... 

    Fault-resilient lightweight cryptographic block ciphers for secure embedded systems

    , Article IEEE Embedded Systems Letters ; Vol. 6, issue. 4 , 2014 , pp. 89-92 ; ISSN: 19430663 Mozaffari Kermani, M ; Tian, K ; Azarderakhsh, R ; Bayat Sarmadi, S ; Sharif University of Technology
    Abstract
    The development of extremely-constrained embedded systems having sensitive nodes such as RFID tags and nanosensors necessitates the use of lightweight block ciphers. Nevertheless, providing the required security properties does not guarantee their reliability and hardware assurance when the architectures are prone to natural and malicious faults. In this letter, error detection schemes for lightweight block ciphers are proposed with the case study of XTEA (eXtended TEA). Lightweight block ciphers such as XTEA, PRESENT, SIMON, and the like might be better suited for low-resource deeply-embedded systems compared to the Advanced Encryption Standard. Three different error detection approaches... 

    Design of a fault tolerated intelligent cntrol system for a nuclear reactor power control: Using extended Kalman filter

    , Article Journal of Process Control ; Vol. 24, issue. 7 , 2014 , pp. 1076-1084 ; ISSN: 09591524 Hatami, E ; Salarieh, H ; Vosoughi, N ; Sharif University of Technology
    Abstract
    In this paper an approach based on system identification is used for fault detection in a nuclear reactor. A continuous-time Extended Kalman Filter (EKF) is presented, which allows the parameters of the nonlinear system to be estimated. Also a fault tolerant control system is designed for the nuclear reactor during power changes operation. The proposed controller is an adaptive critic-based neuro-fuzzy controller. Performance of the controller in terms of transient response and robustness against failures is very good and considerable  

    Fast short circuit power switch fault detection in cascaded H-bridge multilevel converter

    , Article IEEE Power and Energy Society General Meeting ; 2013 ; 19449925 (ISSN); 9781479913039 (ISBN) Shahbazi, M ; Zolghadri, M. R ; Poure, P ; Saadate, S ; Sharif University of Technology
    2013
    Abstract
    Multilevel converters are being widely used in a large number of power electronics applications. Due to the increased number of switching devices, they are more likely to have faults in their switches than the conventional converters. In order to have a balanced operation after a short circuit power switch fault occurrence, it is necessary to detect the fault location. In this paper, a fast power switch fault detection method is presented to identify the fault location. This method only needs one additional voltage sensor per phase, and is faster compared to most of the existing methods. Also it is easy for implementation on a FPGA chip. The proposed method is verified by computer... 

    FPGA-based fast detection with reduced sensor count for a fault-tolerant three-phase converter

    , Article IEEE Transactions on Industrial Informatics ; Volume 9, Issue 3 , 2013 , Pages 1343-1350 ; 15513203 (ISSN) Mahmoud, M ; Philippe, P ; Shahrokh, S ; Mohammad Reza, M. R ; Sharif University of Technology
    2013
    Abstract
    Fast fault detection (FD) and reconfiguration is necessary for fault tolerant power electronic converters in safety critical applications to prevent further damage and to make the continuity of service possible. The aim of this study is to minimize the number of the used additional voltage sensors in a fault tolerant three-phase converter. In this paper, first a practical implementation of a very fast FD scheme with reduced sensor number is discussed. Then, an optimization in this scheme is also presented to decrease the detection time. For FD, special time and voltage criterion are applied to observe the error in the estimated phase-to-phase voltages for a specific period of time. The... 

    A heuristic threshold policy for fault detection and diagnosis in multivariate statistical quality control environments

    , Article International Journal of Advanced Manufacturing Technology ; Volume 67, Issue 5-8 , July , 2013 , Pages 1231-1243 ; 02683768 (ISSN) Nezhad, M. S. F ; Niaki, S. T. A ; Sharif University of Technology
    2013
    Abstract
    In this paper, a heuristic threshold policy is developed to detect and classify the states of a multivariate quality control system. In this approach, a probability measure called belief is first assigned to the quality characteristics and then the posterior belief of out-of-control characteristics is updated by taking new observations and using a Bayesian rule. If the posterior belief is more than a decision threshold, called minimum acceptable belief determined using a heuristic threshold policy, then the corresponding quality characteristic is classified out-of-control. Besides using a different approach, the main difference between the current research and previous works is that the... 

    Open-and short-circuit switch fault diagnosis for nonisolated DC-DC converters using field programmable gate array

    , Article IEEE Transactions on Industrial Electronics ; Volume 60, Issue 9 , October , 2013 , Pages 4136-4146 ; 02780046 (ISSN) Shahbazi, M ; Jamshidpour, E ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
    2013
    Abstract
    Fault detection (FD) in power electronic converters is necessary in embedded and safety critical applications to prevent further damage. Fast FD is a mandatory step in order to make a suitable response to a fault in one of the semiconductor devices. The aim of this study is to present a fast yet robust method for fault diagnosis in nonisolated dc-dc converters. FD is based on time and current criteria which observe the slope of the inductor current over the time. It is realized by using a hybrid structure via coordinated operation of two FD subsystems that work in parallel. No additional sensors, which increase system cost and reduce reliability, are required for this detection method. For... 

    Wind energy conversion system based on DFIG with open switch fault tolerant six-legs AC-DC-AC converter

    , Article Proceedings of the IEEE International Conference on Industrial Technology, Cape Town ; February , 2013 , Pages 1656-1661 ; 9781467345699 (ISBN) Shahbazi, M ; Zolghadri, M. R ; Poure, P ; Saadate, S ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES); IEEE Technology Management Council; IEEE Region 8; IEEE South Africa Section IE/IA/PEL Joint Chapter ; Sharif University of Technology
    2013
    Abstract
    Continuity of service of wind energy conversion systems as well as their reliability and performances are some of the major concerns in this power generation area. Six-legs AC/DC/AC converters are normally used in modern wind energy systems like as in the system with a doubly-fed induction generator (DFIG). A sudden failure of the converter can lead to the total or partial loss of the control of the phase currents and can cause serious system malfunction or shutdown. Therefore, to prevent the spread of the fault to the other system components and to ensure continuity of service, fault tolerant converter topologies associated to quick and effective fault detection and compensation methods... 

    FPGA-based reconfigurable control for fault-tolerant back-to-back converter without redundancy

    , Article IEEE Transactions on Industrial Electronics ; Volume 60, Issue 8 , May , 2013 , Pages 3360-3371 ; 02780046 (ISSN) Shahbazi, M ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
    2013
    Abstract
    In this paper, an FPGA-based fault-tolerant back-to-back converter without redundancy is studied. Before fault occurrence, the fault-tolerant converter operates like a conventional back-to-back six-leg converter, and after the fault, it becomes a five-leg converter. Design, implementation, and experimental verification of an FPGA-based reconfigurable control strategy for this converter are discussed. This reconfigurable control strategy allows the continuous operation of the converter with minimum affection from a fault in one of the semiconductor switches. A very fast detection scheme is used to detect and locate the fault. Implementation of the fault detection and of the fully digital... 

    Fault-tolerant five-leg converter topology with FPGA-Based reconfigurable control

    , Article IEEE Transactions on Industrial Electronics ; Volume 60, Issue 6 , 2013 , Pages 2284-2294 ; 02780046 (ISSN) Shahbazi, M ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
    2013
    Abstract
    Fast fault detection and reconfiguration of power converters is necessary in electrical drives to prevent further damage and to make the continuity of service possible. On the other hand, component minimized converters may provide the benefits of higher reliability and less volume and cost. In this paper, a new fault-tolerant converter topology is studied. This converter has five legs before the fault occurrence, and after fault detection the converter continues to function with four legs. A very fast fault detection and reconfiguration scheme is presented and studied. Simulations and experimental tests are performed to evaluate the structure requirements, the digital reconfigurable... 

    On-line fault detection and isolation (FDI) for the exhaust path of a turbocharged SI engine

    , Article ASME 2013 Dynamic Systems and Control Conference, DSCC 2013 ; Volume 1 , 2013 ; 9780791856123 (ISBN) Salehi, R ; Shahbakhti, M ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    2013
    Abstract
    Detection and isolation of faults in the exhaust gas path of a turbocharged spark ignition (SI) engine is an essential part of the engine control unit (ECU) strategies to minimize exhaust emission and ensure safe operation of a turbocharger. This paper proposes a novel physics-based strategy to detect and isolate an exhaust manifold leakage and a closed-stuck wastegate fault. The strategy is based on a globally optimal parameter estimation algorithm which detects an effective hole area in the exhaust manifold. The estimation algorithm requires prediction of the exhaust manifold's input and output flows. The input flow is predicted by a nonlinear Luenberger observer which is analytically... 

    Low-cost scan-chain-based technique to recover multiple errors in TMR systems

    , Article IEEE Transactions on Very Large Scale Integration (VLSI) Systems ; Volume 21, Issue 8 , 2013 , Pages 1454-1468 ; 10638210 (ISSN) Ebrahimi, M ; Miremadi, S. G ; Asadi, H ; Fazeli, M ; Sharif University of Technology
    2013
    Abstract
    In this paper, we present a scan-chain-based multiple error recovery technique for triple modular redundancy (TMR) systems (SMERTMR). The proposed technique reuses scan-chain flip-flops fabricated for testability purposes to detect and correct faulty modules in the presence of single or multiple transient faults. In the proposed technique, the manifested errors are detected at the modules' outputs, while the latent faults are detected by comparing the internal states of the TMR modules. Upon detection of any mismatch, the faulty modules are located and the state of a fault-free module is copied into the faulty modules. In case of detecting a permanent fault, the system is degraded to a... 

    An appropriate procedure for detection of journal-bearing fault using power spectral density, K-nearest neighbor and support vector machine

    , Article International Journal on Smart Sensing and Intelligent Systems ; Volume 5, Issue 3 , 2012 , Pages 685-700 ; 11785608 (ISSN) Moosavian, A ; Ahmadi, H ; Tabatabaeefar, A ; Sakhaei, B ; Sharif University of Technology
    2012
    Abstract
    Journal-bearings play a significant role in industrial applications and the necessity of condition monitoring with nondestructive tests is increasing. This paper deals a proper fault detection technique based on power spectral density (PSD) of vibration signals in combination with K-Nearest Neighbor and Support Vector Machine (SVM). The frequency domain vibration signals of an internal combustion engine with three journal-bearing conditions were gained, corresponding to, (i) normal, (ii) corrosion and (iii) excessive wear. The features of the PSD values of vibration signals were extracted using statistical and vibration parameters. The extracted features were used as inputs to the KNN and... 

    Comparison of transfer functions using estimated rational functions to detect winding mechanical faults in transformers

    , Article Archives of Electrical Engineering ; Volume 61, Issue 1 , 2012 , Pages 85-99 ; 00040746 (ISSN) Bigdeli, M ; Vakilian, M ; Rahimpour, E ; Sharif University of Technology
    2012
    Abstract
    As it is found in the related published literatures, the transfer function (TF) evaluation method is the most feasible method for detection of winding mechanical faults in transformers. Therefore, investigation of an accurate method for evaluation of the TFs is very important. This paper presents three new indices to compare the transformer TFs and consequently to detect the winding mechanical faults. These indices are based on estimated rational functions. To develop the method, the necessary measurements are carried out on a 1.3 MVA transformer winding, under intact condition, as well as different fault conditions (axial displacement of winding). The obtained results demonstrate the high... 

    A low cost circuit level fault detection technique to full adder design

    , Article 2011 18th IEEE International Conference on Electronics, Circuits, and Systems, ICECS 2011, 11 December 2011 through 14 December 2011, Beirut ; 2011 , Pages 446-450 ; 9781457718458 (ISBN) Mozafari, S. H ; Fazeli, M ; Hessabi, S ; Miremadi, S. G ; Sharif University of Technology
    2011
    Abstract
    This paper proposes a Low Cost circuit level Fault Detection technique called LCFD for a one-bit Full Adder (FA) as the basic element of adder circuits. To measure the fault detection coverage of the proposed technique, we conduct an exhaustive circuit level fault injection experiment on all susceptible nodes of a FA. Experimental results show that the LCDF technique can detect about 83% of injected faults while having only about 40% area and 22% power consumption overheads. In the LCDF technique, the fault detection latency does not affect the latency of the FA, since the error detection is done in parallel with the addition  

    FPGA-based fault tolerant scheme with reduced extra-sensor number for WECS with DFIG

    , Article Proceedings - ISIE 2011: 2011 IEEE International Symposium on Industrial Electronics, 27 June 2011 through 30 June 2011 ; 2011 , Pages 1595-1601 ; 9781424493128 (ISBN) Shahbazi, M ; Gaillard, A ; Poure, P ; Zolghadri, M. R ; Sharif University of Technology
    2011
    Abstract
    Fast fault detection and converter reconfiguration is necessary for fault tolerant doubly fed induction generator (DFIG) in wind energy conversion systems (WECS) to prevent further damage and to make possible the continuity of service. Extra sensors are needed in order to detect the faults rapidly. In this paper, a very fast FPGA-based fault detection scheme is presented that minimizes the number of additional voltage sensors. A fault tolerant converter topology for this application is studied. Control and fault detection system are implemented on a single FPGA and Hardware in the Loop experiments are performed to evaluate the proposed detection scheme, the digital controller and the fault... 

    ScTMR: A scan chain-based error recovery technique for TMR systems in safety-critical applications

    , Article Proceedings -Design, Automation and Test in Europe, DATE, 14 March 2011 through 18 March 2011 ; March , 2011 , Pages 289-292 ; 15301591 (ISSN) ; 9783981080179 (ISBN) Ebrahimi, M ; Miremadi, S. G ; Asadi, H ; Sharif University of Technology
    2011
    Abstract
    We propose a roll-forward error recovery technique based on multiple scan chains for TMR systems, called Scan chained TMR (ScTMR). ScTMR reuses the scan chain flip-flops employed for testability purposes to restore the correct state of a TMR system in the presence of transient or permanent errors. In the proposed ScTMR technique, we present a voter circuitry to locate the faulty module and a controller circuitry to restore the system to the fault-free state. As a case study, we have implemented the proposed ScTMR technique on an embedded processor, suited for safety-critical applications. Exhaustive fault injection experiments reveal that the proposed architecture has the error detection and... 

    Fast detection of open-switch faults with reduced sensor count for a fault-tolerant three-phase converter

    , Article 2011 2nd Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2011 ; 2011 , Pages 546-550 ; 9781612844213 (ISBN) Shahbazi, M ; Zolghadri, M ; Poure, P ; Saadate, S ; Sharif University of Technology
    Abstract
    Fast fault detection and reconfiguration is necessary in power electronic converters in lots of applications to prevent further damage and to make possible the continuity of service. In this paper a very fast fault detection scheme is presented that minimizes the use of voltage sensors. A fault tolerant topology is studied. Control and fault detection system are implemented on a single FPGA and hardware in the loop experiments are performed to evaluate the detection scheme, the digital controller and the structure  

    Six-leg AC-AC fault tolerant converter with reduced extra-sensor number

    , Article International Review of Electrical Engineering ; Volume 6, Issue 1 , 2011 , Pages 132-138 ; 18276660 (ISSN) Shahbazi, M ; Poure, P ; Zolghadri, M. R ; Saadate, S ; Sharif University of Technology
    Abstract
    In order to prevent further damage and to provide the continuity of service of six-leg converter in case of open-switch fault, it is mandatory to perform fast fault detection and converter reconfiguration schemes. Extra sensors are needed to detect the faults rapidly. In this paper, a very fast FPGA-based fault detection scheme is presented that minimizes the number of additional voltage sensors. A six-leg fault tolerant converter topology without redundancy and with bidirectional power flow is studied. First simulations are carried out to evaluate the proposed fault detection principle and the fault tolerant converter topology. The fully digital control and the fault detection are...