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Volume 146
Issue 6
IEE Proceedings - Science, Measurement and Technology
Volume 146, Issue 6, November 1999
Volumes & issues:
Volume 146, Issue 6
November 1999
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- Author(s): S.M.T. Almodarresi Yasin and N.M. White
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 265 –269
- DOI: 10.1049/ip-smt:19990679
- Type: Article
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p.
265
–269
(5)
The authors present a new method for dynamic weighing, using a feature extractor and two-layer artificial neural network capable of predicting the final value of the sensor response in a noisy environment while it is still in oscillation. The method permits arbitrary input and initial conditions and requires no restriction on the order of the sensor. Introducing a pre-processor as a feature extraction block before the neural network dramatically reduces the required number of neurones. This, in turn, reduces the complexity of computation and offers the possibility of real-time procedures for dynamic force measurements. The proposed method is established by theoretical analysis and justified by means of both simulation and real data measurements. - Author(s): S. Konishi and K. Yamasawa
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 270 –276
- DOI: 10.1049/ip-smt:19990654
- Type: Article
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p.
270
–276
(7)
A diagnostic system for dry pumps is proposed. It predicts future pump motor current from time-series in-situ measurements. The prediction system has been constructed using a data acquisition system with an online system identification software algorithm. A field test on a low pressure chemical vapour deposition (LPCVD) system for the silicon nitride process predicted large values of motor current, some of which correlated well with actual motor currents as the pump became clogged. The combined use of the predicted motor current and the stability criteria shows promise in predicting the actual service life of a dry pump. - Author(s): D.M. Hepburn ; I.J. Kemp ; A.J. Shields ; J.M. Cooper
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 277 –284
- DOI: 10.1049/ip-smt:19990678
- Type: Article
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p.
277
–284
(8)
Epoxy resin is moulded to produce high voltage insulation components. To release the component from the mould, among other techniques, silicon-based release agents are used. The authors demonstrate that release agent is absorbed by resin during casting, and describe the change in reaction to electrical discharge stressing. Partial discharge stressing of epoxy resin contaminated with release agent causes surface crazing and silicon products, not evident prior to stressing, are detectable on the surface. Noncontaminated samples exhibit signs of erosion and chemical change, but show no evidence of cracking nor of silicon products. Chemical, mechanical and radiative stresses applied to contaminated resin failed to produce silicon material on the resin surface. It is proposed that partial discharge stressing of noncontaminated resin causes erosion of the sample surface, producing volatile products and chemical changes: there is no crazing of the surface layer, as the pure resin is homogeneous. Partial discharge stressing of contaminated epoxy resin results in erosion of the organic resinous material, but leaves nonvolatile silicon products on the resin surface. These mask the chemical changes occurring in the resin: the surface crazing is due to a differential stress reaction between the contaminated surface layer and the noncontaminated region below. - Author(s): S. Zoledziowski
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 285 –291
- DOI: 10.1049/ip-smt:19990677
- Type: Article
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p.
285
–291
(7)
Activation energies, ~0.8 eV, of charges relaxing linearly or rotationally increase in steps of ~10-2 eV due to equal quantum decreases of self-energy of depolarising dipoles. Plots of logarithm of current against time display series of straight sections defining relaxation time constants. A quantum approach allows derivation of several parameters and physical constants so far unobtainable from relaxation data. Linear superposition appears to be no longer valid in the nonequilibrium states. Complex permittivity variations with frequency can be attributed to the quantum changes of the self-energy of dipoles. - Author(s): B.W. Jervis ; M. Thomlinson ; C. Mair ; J.M.L. Lopez ; M.I.B. Garcia
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 293 –298
- DOI: 10.1049/ip-smt:19990703
- Type: Article
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p.
293
–298
(6)
A method based on the vector representation of electro-oculogram (EOG) and electroencephalogram (EEG) signals has been developed for quantifying in simulation the amount of residual ocular artefact (OA) contamination of EEGs after the application of an EOG-based OA removal (OAR) algorithm. The residual artefact is measured as R2, the ratio of residual OA power to the estimated background EEG power. Two types of OA model, the in-plane and the out-of-plane model, were introduced. Values of R2 were computed using simulated contaminated EEGs, which were constructed using measured EEGs, contaminated by a variety of eye movements and blinks, and measured EOG signals. In most cases the estimate of R2 was approximately 0.03, corresponding to a 17% modification of the EEG voltage. The radial component contributed up to 30% of the residual artefact power. For practical applications, the use of the vertical and horizontal right and the radial EOG components was found to be preferred. - Author(s): B.S. Oyegoke
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 299 –303
- DOI: 10.1049/ip-smt:19990680
- Type: Article
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p.
299
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A special aspect of the voltage distribution in the coils of electrical machines when exposed to a fast-rising surge, namely the influence of the winding parameters, especially the capacitance matrix for the slot and overhang parts of the winding, is considered. To model the capacitance, three methods have been applied. For voltage calculation, the multi-conductor transmission line theory has been combined with the scatter matrix in accordance with previous authors. It is shown that, whichever method is to be used for the computation of the capacitance, care must be taken to evaluate the capacitance to the ground in overhang region. Experimental and computational results are presented. Although no account has been taken of the effect of the high frequency magnetic flux penetrating into the laminated core at high frequency, yet peak voltages across turns that might be of immediate importance to machine designers are well predicted. In a motor with a multi-turn coil winding, the effect of the high frequency magnetic flux penetrating into the laminated core may not be the key factor that determines the amplitude of the inter-turn voltage in the multi-turn winding when confronted by a fast-rising surge. The amplitude of the inter-turn voltage to a certain extent depends on the dielectric permittivity used when computing the capacitance to the ground in the overhang part, and the dielectric permittivity used when calculating the velocity of surge propagation in the winding. - Author(s): S.-C. Wang and C.-L. Chen
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 146, Issue 6, p. 304 –308
- DOI: 10.1049/ip-smt:19990527
- Type: Article
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p.
304
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A PC-based automatic characterisation system (ACS) has been developed to automatically characterise magnetic materials under square wave cyclic excitation from 1 kHz to 100 kHz. A computer-controlled AC to AC converter has been developed for the excitation circuit. A digital oscilloscope gathers the required data through the 8255 interface card. The errors in the ACS have been analysed and overall repeatability is better than ±0.35%. The system has the advantages of ease of use, absence of long-term measuring system drifts and ready variation of high induction and high frequency test parameters. The system operates automatically and measurements on three commercial core materials are reported. Comparisons with the data of manufacturers are included.
Application of artificial neural networks to intelligent weighing systems
Diagnostic system to determine the in-service life of dry vacuum pumps
Effect of mould release agent on epoxy resin surface degradation
Spectrometry of quantised thermal relaxations of polarisations in a solid
Residual ocular artefact subsequent to ocular artefact removal from the electroencephalogram
Effect of the overhang capacitance on fast-rising surge distribution in winding of a large AC motor
PC-based apparatus for characterising high frequency magnetic cores
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