Saturday, November 27, 2010


.                           Mark, W. D., Lee, H., Patrick, R., and Coker, J. D., Mechanical Systems and Signal Processing 24(8), 2807 (2010).
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Ref ID: 1
Abstract: Fixed transducers often are used to monitor meshing gear pairs in order to detect tooth damage A simple frequency-domain damage-detection algorithm is suggested for very early detection of such damage. Ratios of rotational-harmonic amplitudes computed from before and after potential damage are utilized to eliminate effects of transducer and structural-path-caused amplitude changes between tooth-meshing location and transducer output, to minimize attenuating effects of multiple-tooth contact, and thereby, to approximately equally weight rotational-harmonic amplitudes over a wide range of harmonics. Statistical averaging of absolute values of logarithmic ratios of rotational-harmonic amplitudes is used to minimize fluctuations caused by multiple-tooth contact and manufacturing errors on the subject gear. Synchronous averaging is employed to minimize effects of noise and manufacturing errors on the mating gear. Time-windowing tailored to contact ratios of mating gears is utilized to isolate individual tooth locations. Resultant windowing effects on availability of useful rotational harmonics are analyzed. Application of the algorithm to detection of seeded bending-fatigue faults on a planetary ring-gear tooth indicates that successful detections were achieved. (C) 2010 Elsevier Ltd. All rights reserved
               . Rigatos, G., Siano, P., and Piccolo, A., Iet Generation Transmission & Distribution 3(7), 650 (2009).
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Ref ID: 2
Abstract: This study proposes neural modelling and fault diagnosis methods for the early detection of cascading events in electric power systems. A neural-fuzzy network is used to model the dynamics of the power transmission system in fault-free conditions. The output of the neural-fuzzy network is compared to measurements from the power system and the obtained residuals undergo statistical processing according to a fault detection and isolation algorithm. If a fault threshold, defined by the fault detection and isolation (FDI) algorithm, is exceeded then deviation from normal operation can be detected at its early stages and an alarm can be launched. In several cases fault isolation can be also performed, that is the sources of fault in the power transmission system can be also identified. The performance of the proposed methodology is tested through simulation experiments
                           Zin, A. A. M. and Karim, S. P. A., Ieee Transactions on Power Delivery 22(4), 2040 (2007).
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Ref ID: 4
Abstract: The protection system is a very critical element in a power system. It is security to the power system for isolating only, the faulty plant as fast as possible. A simple fault can lead to a cascade of tripping if it is not isolated accurately and fast enough by the, protection system. Furthermore, protection system analysis is a complicated task for inexperienced engineers. Most of the analysis relied mainly on the relay indications which could lead to incorrect analysis due to the uncertainty of the correct relay operations and time tagging. Therefore, I it is an urgent requirement to explore protection system analysis to improve system reliability. This paper describes a method of early detection of protection system failures in Tenaga Nasional Berhad's Transmission Grid using digital fault recorders. The method has demonstrated to be more accurate, thus enabling faster decision making and shorter interruption time
                           Saleh, K. and Al-Saqabi, K., Information and Software Technology 39(14-15), 975 (1998).
Ref Type: Journal
Ref ID: 10
Abstract: The early error detection and the understanding of the nature and conditions of an error occurrence can be useful to make an effective and efficient recovery in distributed systems. Various distributed system extensions were introduced for the implementation of fault tolerance in distributed software systems. These extensions rely mainly on the exchange of contextual information appended to every transmitted application specific message. Ideally, this information should be used for checkpointing, error detection, diagnosis and recovery should a transient failure occur later during the distributed program execution. In this paper, we present a generalized extension suitable for fault-tolerant distributed systems such as communication software systems and its detection capabilities are shown. Our extension is based on the execution of message validity test prior to the transmission of messages and the piggybacking of contextual information to facilitate the detection and diagnosis of transient faults in the distributed system. (C) 1998 Elsevier Science B.V

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