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Total 125 records

    Fault diagnosis in a yeast fermentation bioreactor by genetic fuzzy system

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 29, Issue 3 , 2010 , Pages 61-72 ; 10219986 (ISSN) Tayyebi, S ; Shahrokhi, M ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    Abstract
    In this paper, the fuzzy system has been used for fault detection and diagnosis of a yeast fermentation bioreactor based on measurements corrupted by noise. In one case, parameters of membership functions are selected in a conventional manner. In another case, using certainty factors between normal and faulty conditions the optimal values of these parameters have been obtained through the genetic algorithm. These two cases are compared based on their performances in fault diagnosis of a yeast fermentation bioreactor for three different conditions. The simulation results indicate that the fuzzy-genetic system is superior in multiple fault detection for the conditions where the minimum and... 

    Fast fault detection method for modular multilevel converter semiconductor power switches

    , Article IET Power Electronics ; Volume 9, Issue 2 , 2016 , Pages 165-174 ; 17554535 (ISSN) Haghnazari, S ; Khodabandeh, M ; Zolghadri, M. R ; Sharif University of Technology
    Institution of Engineering and Technology  2016
    Abstract
    This study proposes a new fault detection method for modular multilevel converter (MMC) semiconductor power switches. While in common MMCs, the cells capacitor voltages are measured directly for control purposes, in this study voltage measurement point changes to the cell output terminal improving fault diagnosis ability. Based on this measurement reconfiguration, a novel fault detection algorithm is designed for MMCs semiconductor power switches. The open circuit and short circuit faults are detected based on unconformity between modules output voltage and switching signals. Simulation and experimental results confirm accurate and fast operation of the proposed method in faulty cell... 

    A geometric approach to fault detection and isolation in robotic manipulators

    , Article Proceedings of the IEEE Conference on Decision and Control, 17 December 2018 through 19 December 2018 ; Volume 2018-December , 2019 , Pages 391-396 ; 07431546 (ISSN); 9781538613955 (ISBN) Karami, S ; Namvar, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    We present a geometric approach for fault detection and isolation (FDI) in robotic manipulators in presence of model uncertainty. A systematic procedure is introduced for representing robotic system model being affine with respect to faults and disturbances. The proposed residual generator has smooth dynamics with freely selectable functions and it does not require high gains or threshold adjustment for the FDI purpose. No assumption on amplitude of faults and their rate is used. The solvability conditions for the FDI problem lead to a quotient observable subspace unaffected by all unknown inputs except the faults. Simulation example demonstrates localization of faults in presence of... 

    Geometric-based fault diagnosis in a grid-connected inverter

    , Article Proceedings of the IEEE Conference on Decision and Control, 17 December 2018 through 19 December 2018 ; Volume 2018-December , 2019 , Pages 3421-3426 ; 07431546 (ISSN); 9781538613955 (ISBN) Mashreghi, A ; Namvar, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper presents a nonlinear geometric approach to fault detection and isolation (FDI) in grid-connected inverters. Faults are considered in inverter switches as well as in grid voltage and source current sensors. The FDI system is not sensitive to load variations or grid transients. No assumptions on balanced, zero-sum or sinusoidal form of voltages or currents are made. The resulting residual converges to zero in no-fault condition such that no threshold adjustment is needed. Simulations demonstrate performance of the proposed FDI system in presence of unknown disturbance. © 2018 IEEE  

    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... 

    Multiple upsets tolerance in SRAM memory

    , Article 2007 IEEE International Symposium on Circuits and Systems, ISCAS 2007, New Orleans, LA, 27 May 2007 through 30 May 2007 ; 2007 , Pages 365-368 ; 02714310 (ISSN) Argyrides, C ; Zarandi, H. R ; Pradhan, D. K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2007
    Abstract
    This paper presents a high level method called Matrix code to protect SRAM-based memories against multiple bit upsets. The proposed method combines hamming code and parity code to assure the reliability of memory in presence of multiple bit-upsets with low area and performance overhead. The method is evaluated using one million multiple-fault injection experiments; next reliability and MTTF of the protected memories are estimated based on fault injection experiments and several equations. The fault detection/correction coverage are also calculated and compared with previous methods i.e., Reed-Muller and hamming code. The results reveal that the proposed method behaves better than these... 

    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... 

    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... 

    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... 

    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... 

    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  

    A Second-Order Sliding Mode Observer for Fault Detection and Isolation of Turbocharged SI Engines

    , Article IEEE Transactions on Industrial Electronics ; Volume 62, Issue 12 , June , 2015 , Pages 7795-7803 ; 02780046 (ISSN) Salehi, R ; Vossoughi, G ; Alasty, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    This paper proposes a novel method for detection and isolation of wastegate (WG) faults in a turbocharged (TC) gasoline engine. This paper starts with a fault effect analysis on the WG faults, including WG stuck open and stuck closed, which is an early step in a detection strategy design. Then, a second-order sliding-mode observer (SOSMO) is proposed to capture the exhaust manifold dynamics. The observer uses experimentally validated engine models to estimate the WG position and a virtual force. The virtual force represents the external disturbances that disrupt the WG operation and enables the proposed SOSMO to estimate the WG position robust to the faults. Using this force, a detection and... 

    Failure detection and isolation in robotic manipulators using joint torque sensors

    , Article Robotica ; Volume 28, Issue 4 , 2010 , Pages 549-561 ; 02635747 (ISSN) Namvar, M ; Aghili, F ; Sharif University of Technology
    2010
    Abstract
    Reliability of any model-based failure detection and isolation (FDI) method depends on the amount of uncertainty in a system model. Recently, it has been shown that the use of joint torque sensing results in a simplified manipulator model that excludes hardly identifiable link dynamics and other nonlinearities such as friction, backlash, and flexibilities. In this paper, we show that the application of the simplified model in a fault detection algorithm increases reliability of fault monitoring system against modeling uncertainty. The proposed FDI filter is based on a smooth velocity observer of degree 2n where n stands for the number of manipulator joints. No velocity measurement and... 

    Fault diagnosis in robot manipulators in presence of modeling uncertainty and sensor noise

    , Article Proceedings of the IEEE International Conference on Control Applications, 8 July 2009 through 10 July 2009, Saint Petersburg ; 2009 , Pages 1750-1755 ; 9781424446025 (ISBN) Mohseni, S ; Namvar, M ; Sharif University of Technology
    Abstract
    In this paper, we introduce a new approach to fault detection and isolation for robot manipulators. Our technique is based on using a new simplified Euler-Lagrange (EL) equation that reduces complexity of the proposed fault detection method. The proposed approach isolates the faults and is capable of handling the uncertainty in manipulator gravity vector. It is shown that the effect of uncalibrated torque sensor measurement is asymptotically rejected in the detection process. A simulation example is presented to illustrate the results. © 2009 IEEE  

    Fault detection and isolation of satellite gyroscopes using relative positions in formation flying

    , Article Aerospace Science and Technology ; Volume 78 , 2018 , Pages 403-417 ; 12709638 (ISSN) Shakouri, A ; Assadian, N ; Sharif University of Technology
    Elsevier Masson SAS  2018
    Abstract
    A fault detection and isolation method for satellite rate gyros is proposed based on using the satellite-to-satellite measurements such as relative position beside orbit parameters of the primary satellite. By finding a constant of motion, it is shown that the dynamic states in a relative motion are restricted in such a way that the angular velocity vector of primary satellite lies on a quadratic surface. This constant of motion is then used to detect the gyroscope faults and estimate the corresponding scale factor or bias values of the rate gyros of the primary satellite. The proposed algorithm works even in time variant fault situations as well, and does not impose any additional... 

    Reliable hardware architectures for efficient secure hash functions ECHO and fugue

    , Article 15th ACM International Conference on Computing Frontiers, CF 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 204-207 ; 9781450357616 (ISBN) Mozaffari Kermani, M ; Azarderakhsh, R ; Bayat Sarmadi, S ; ACM Special Interest Group on Microarchitectural Research and Processing (SIGMICRO) ; Sharif University of Technology
    Association for Computing Machinery, Inc  2018
    Abstract
    In cryptographic engineering, extensive attention has been devoted to ameliorating the performance and security of the algorithms within. Nonetheless, in the state-of-the-art, the approaches for increasing the reliability of the efficient hash functions ECHO and Fugue have not been presented to date.We propose efficient fault detection schemes by presenting closed formulations for the predicted signatures of different transformations in these algorithms. These signatures are derived to achieve low overhead for the specific transformations and can be tailored to include byte/word-wide predicted signatures. Through simulations, we show that the proposed fault detection schemes are... 

    Improvement of fault detection in wireless sensor networks

    , Article 2009 Second ISECS International Colloquium on Computing, Communication, Control, and Management, CCCM 2009, Sanya, 8 August 2009 through 9 August 2009 ; Volume 4 , 2009 , Pages 644-646 ; 9781424442461 (ISBN) Khazaei, E ; Barati, A ; Movaghar, A ; Yangzhou University; Guangdong University of Business Studies; Wuhan Institute of Technology; IEEE SMC TC on Education Technology and Training; IEEE Technology Management Council ; Sharif University of Technology
    2009
    Abstract
    This paper presents a centralized fault detection algorithm for wireless sensor networks. Faulty sensor nodes are identified based on comparisons between neighboring nodes and own central node and dissemination of the decision made at each node. RNS system is used to tolerate transient faults in sensing and communication. In this system, arithmetic operations act on residues - reminder of dividing original number in several definite modules - in parallel. Consequently computations on these residues which are smaller than the original number are performed, so speed up arithmetic and decreased power consumption is achieved. ©2009 IEEE  

    Smooth residual generation for robust isolation of faults in manipulators using joint torque sensors

    , Article 58th IEEE Conference on Decision and Control, CDC 2019, 11 December 2019 through 13 December 2019 ; Volume 2019-December , 2019 , Pages 2922-2927 ; 07431546 (ISSN); 9781728113982 (ISBN) Karami, S ; Namvar, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Reliability of model-based failure detection and isolation (FDI) methods depends on the amount of uncertainty in a system model. Recently, it has been shown that the use of joint torque sensing results in a simplified manipulator model that excludes hardly identifiable link dynamics and other nonlinearities. We present a geometric approach to fault detection and isolation (FDI) for robotic manipulators using joint torque sensor in presence of model uncertainty. A systematic procedure is introduced for representing a robotic system model using joint torque sensor being affine with respect to faults and disturbances. The proposed FDI filter has smooth dynamics with freely selectable functions... 

    High-Performance Fault Diagnosis Schemes for Efficient Hash Algorithm BLAKE

    , Article 10th IEEE Latin American Symposium on Circuits and Systems, LASCAS 2019, 24 February 2019 through 27 February 2019 ; 2019 , Pages 201-204 ; 9781728104522 (ISBN) Mozaffari Kermani, M ; Bayat Sarmadi, S ; Ackie, A. B ; Azarderakhsh, R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Augmenting the security of cryptographic algorithms by protecting them against side-channel active attacks (and natural faults) is essential in cryptographic engineering. BLAKE algorithm is an efficient hash function which has been developed based on Bernstein's ChaCha stream cipher. Because of the fact that Google has chosen ChaCha along with Bernstein's Poly1305 message authentication code as a replacement for RC4 in TLS for Internet security, BLAKE's implementation is of paramount importance. In this paper, we present high-performance fault detection schemes for BLAKE. Specifically, for the round function, two fault diagnosis approaches are developed and analyzed in terms of error... 

    Fault detection and protection strategy for islanded inverter-based microgrids

    , Article IEEE Journal of Emerging and Selected Topics in Power Electronics ; 2019 ; 21686777 (ISSN) Zarei, S. F ; Mokhtari, H ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    This paper proposes a fault detection and protection strategy for islanded inverter-based microgrids (IBMGs). Reliable and accurate protection is one of the main challenges in the proliferation of modern microgrids (MGs). Considering the limited fault current of the voltage-frequency controlled inverter-based distributed energy resources (VF-IBDERs), the protection is more challenging in islanded IBMGs. In this regard, the control scheme of VF-IBDER with a current limiting strategy plays an important role. Due to the limited fault currents close to the converter nominal current, the conventional fault detection methods do not work properly. In addition, bi-directional fault currents worsen...