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Volume 144
Issue 6
IEE Proceedings - Science, Measurement and Technology
Volume 144, Issue 6, November 1997
Volumes & issues:
Volume 144, Issue 6
November 1997
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- Author(s): S. McCulloch and D. Uttamchandani
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 241 –246
- DOI: 10.1049/ip-smt:19971473
- Type: Article
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p.
241
–246
(6)
Miniaturised fibre optic chemical sensors continue to be developed in a number of research laboratories around the world. Such fibre optic sensors originate from work originally undertaken during the development of nanometric aperture probes used in scanning near-field optical microscopes. The probes can be converted to sensors for highly localised chemical measurements by attaching the appropriate chemical indicators to the probe tips. The term ‘optrode’ has been widely used to describe a sensor utilising optical detection methods, and the authors introduce the term ‘micro-optrode’ to describe their miniaturised fibre optic sensors, which possess a high spatial resolution. The authors present recent results obtained in their laboratories where they have constructed such sensors using chemically sensitised sol–gel glasses. - Author(s): B.Z. Kaplan and U. Suissa
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 247 –251
- DOI: 10.1049/ip-smt:19971528
- Type: Article
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p.
247
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The covering fieldmill is used for measuring electrical DC field, and its theoretical treatment in the literature is not detailed. The authors have developed an unusual model that enables a comprehensive treatment of the sensor. It is based on a viewpoint borrowed from antenna theory. The authors regard the sensor as a very small antenna coupled to the field sources by a small series capacitance. They show, however, that the actual coupling of the sensing system to the sources of the measured field is due to the variation in time of the latter capacitance. One method for evaluating the system is to use a steady state approach that enables the output voltage of the sensor to be related to the field. Another approach uses the system differential equation to simulate the performance via MATLAB. The results of both methods are in complete agreement. Furthermore, the authors show that the results conform with those obtained by the approaches of other authors, regarding the system as periodically chopping the displacement-vector-flux. An interesting outcome of the approach is the proof that the output power of the device is due to the mechanical mover of the fieldmill, and is not supplied by the sources of the measured field. - Author(s): E. Lou ; N.G. Durdle ; V.J. Raso ; D.L. Hill
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 252 –256
- DOI: 10.1049/ip-smt:19971549
- Type: Article
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p.
252
–256
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A low-power electromagnetic multiturn square-loop transmitter-receiver system has been developed to measure the topographical features of a human torso. The paper presents a theoretical analysis of the magnetic field, and derives equations to calculate the self-inductance caused by a three axis orthogonal multiturn square-loop transmitter and receiver. The theoretical and experimental results of the magnetic field are compared at distances ranging from 8 to 26 cm. Results indicate that the strength of the magnetic field on the coaxial arrangement is double that for the coplanar arrangement. The errors of the results on all three axes are less than 1%. Measurement of the inductance shows that more accurate results are obtained for smaller sizes and for a greater number of turns of both transmitter and receiver. - Author(s): S. Ahmed ; P. Russell ; P. Lisboa ; G.R. Jones
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 257 –262
- DOI: 10.1049/ip-smt:19971470
- Type: Article
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p.
257
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A PC-based neural-network processing system is described for the interpretation of chromatic sensor information monitored remotely using a CCD camera. Chromaticity based monitoring provides a means of simple data pre-processing to reduce system noise due to total intensity variation. However, sensing elements using chromaticity usually show complex variations in chromaticity with measurand changes. This contribution shows how these complex variations may be processed to yield high resolution values of a measurand. The paper presents a novel application of neural networks for monitoring temperatures using thermochromic materials and to perform 2-D pressure analysis using photoelastic materials. The inherent complex mapping and generalisation abilities of multi-layered perceptrons (MLP) make them ideal for processing the detected signals. Results are presented showing that the neural network can provide levels of resolution and performance for remotely addressing chromatic transducers, which are acceptable for detailed metrological applications. - Author(s): Q. Xu and A. Refsum
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 263 –266
- DOI: 10.1049/ip-smt:19971530
- Type: Article
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p.
263
–266
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The paper presents a mapping model for the representation of symmetrical B/H characteristics over the whole of the B/H plane, based on neural networks taught by backpropagation. The model could not be achieved accurately by just using a symmetrical saturated hysteresis loop to simulate a smaller hysteresis loop. 11 experimentally obtained hysteresis loops from over the whole of the B/H plane were used to train neural networks. These are good enough to represent all nonlinear hysteresis characteristics to meet the needs of an engineering calculation, e.g. a transient performance analysis of a current transformer or voltage transformer. The simulation accuracy depends ultimately on the accuracy of the experimental data. The computed results using this model have shown a good agreement with measured data. - Author(s): M.K. Oolun
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 267 –272
- DOI: 10.1049/ip-smt:19971531
- Type: Article
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p.
267
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Various techniques for interrogating systems are in current use, each having its own advantages and limitations. The author presents the design, implementation and testing of a PC and DSP based system that combines the well established properties of Golay complementary series with a cross-correlation technique, to perform electrical systems identification. Initially, the author develops the theoretical background and presents Golay codes adapted in a way to suit the application. Details of the design for the prototype model implemented in the work are given, and results of the tests carried out to evaluate the system's performance are reported. It is shown that this new system is capable of working at very high speed and covering a wide frequency spectrum. - Author(s): D.E. Gourgoulis and C.A. Stassinopoulos
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 273 –279
- DOI: 10.1049/ip-smt:19971471
- Type: Article
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p.
273
–279
(7)
Sparkover voltages were measured for quasiuniform field sphere gaps consisting of 75 cm diameter spheres stressed by standard waveshapes of 1.2/50 µs and 250/2500 µs of both polarities. The work was undertaken with the aims of comparison with existing work with 25 cm spheres, and of investigating the breakdown mechanism of such gaps and the effect upon them of the applied impulse voltage, with emphasis on the waveshape, the gap spacing, the polarity, the diameter of the spheres and the absolute humidity. The factors that influence the breakdown mechanism have been studied systematically, in order to ascertain their reliability as measurement standards and, hence, their effect on the sparkover voltage values proposed by the IEC. - Author(s): B.N. Das and S.B. Chakrabarty
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 280 –286
- DOI: 10.1049/ip-smt:19971424
- Type: Article
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p.
280
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The authors present a method of finding the effect of fringing on capacitance and charge distribution of conducting structures consisting of coaxial cylinders or of parallel cylinders of identical diameter, each of finite and equal length. The moment method, employing pulse and delta functions as the basis and testing functions, respectively, is used for the analysis. Numerical data on charge distribution and capacitance per unit length, normalised to the same quantity for similar structure of infinite length, are presented. - Author(s): G.L. Wai and W.J. Bonwick
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 287 –293
- DOI: 10.1049/ip-smt:19971483
- Type: Article
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p.
287
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Partial discharge (PD) pattern recognition systems are often based on analysis of the data structure as a whole. This approach may not explain the underlying discharge processes. An alternative concept is proposed which is based on the examination and analysis of the subspecies identifiable in the data. PD data obtained from a generator stator conductor are used to demonstrate this approach. Using well-behaved data it is possible to identify two distinctive types of discharges originating from a generator stator conductor. One type has properties ascribable to surface discharges, whereas the other type exhibits properties akin to those from internal discharges. The approach allows ill-behaved PD data to be segmented in a supervised manner using knowledge about the likely behaviour of different types of PD. This permits individual PD generating mechanisms to be monitored, which may be difficult to achieve through analysis of the overall magnitude and phase distributions. Using the method, it is demonstrated that the surface discharges have a magnitude distribution whose shape is influenced by a multivalued relationship with the phase distribution. These relationships are obscured if magnitude distribution only is used for the analysis but are observable using subspecies analysis. - Author(s): J.R. Wait
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, page: 294 –294
- DOI: 10.1049/ip-smt:19971520
- Type: Article
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p.
294
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- Author(s): F. Han
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 144, Issue 6, p. 294 –295
- DOI: 10.1049/ip-smt:19971521
- Type: Article
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p.
294
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Development of micro-optrodes using sol–gel immobilisation
Dynamic models of certain DC and low frequency electric field sensors
Measurement of the magnetic field in the near-field region and self-inductance in free space due to a multiturn square-loop
Parameter monitoring using neural-network-processed chromaticity
Neural network for representation of hysteresis loops
Electrical systems identification using Golay complementary series
Spark breakdown of sphere gaps stressed by standard impulse voltages
Capacitance and charge distribution of two cylindrical conductors of finite length
Subspecies analysis of partial discharge data from a generator stator conductor
Comment: Response of underground multiconductor cable systems to external fields illumination
Reply: Response of underground multiconductor cable systems to external fields illumination
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