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Volume 141
Issue 3
IEE Proceedings - Science, Measurement and Technology
Volume 141, Issue 3, May 1994
Volumes & issues:
Volume 141, Issue 3
May 1994
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- Author(s): J. Taboada ; S. Feijoo ; R. Balsa ; C. Hernandez
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 153 –159
- DOI: 10.1049/ip-smt:19949700
- Type: Article
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p.
153
–159
(7)
Estimation of signal length is one of the first steps in many speech processing systems, for it provides us with the initial and final points between which the speech signal is comprised. Nevertheless, endpoint detection can be affected by different types of background noise over which we have no control. This study presents an explicit detector that aims to resolve the problems created by two types of noise: quasi-stationary background noise and the noise generated by the speaker. The system is based on very simple measurements, energy, zero crossing rate and band crossings, and has been implemented on a personal computer. We have tested the system under real-life conditions, and it has attained a success rate of 97-98% in the location of the extremes for both the left and the right limit of a series of words comprising all the possible beginnings and endings in Spanish. - Author(s): S.-T. Lu ; C. Chou ; Y.-P. Wu ; H.-J. King
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 160 –164
- DOI: 10.1049/ip-smt:19949697
- Type: Article
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p.
160
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A Newton-Raphson algorithm for optimising dimension parameters of the electrooptical targeting system (EOTS) is proposed. The spatial parameters are critical to the accuracy of position measurement in the targeting system. To calibrate EOTS, the Newton-Raphson iteration method is used to enhance the system accuracy. This algorithm is based on four tested points where each point is required to be located in four different quadrants in the target area. The Newton-Raphson iteration method minimises the difference between the calculated and the measured values obtained from any of two tested locations. This algorithm enhances the system accuracy up to ±1 mm within a 1 m*1 m targeting area. - Author(s): D.B. Watson and S.K. Kho
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 165 –170
- DOI: 10.1049/ip-smt:19949702
- Type: Article
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p.
165
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The position of the flashover impact point on the plane electrode in a point-plane system has been investigated using both paper and aluminium foil to record the impact points. The impact points are close to the centre at low voltages where the probability of flashover is very low. The spread increases as the voltage is raised through the 100% flashover level, then closes in again towards the centre as higher overvoltages are applied. For a long gap the widest deviation of the impact points from the centre is produced by a negative voltage, but with a small gap the widest deviation is produced by a positive voltage. Although the two methods of recording the impact points yield substantially the same distribution when flashover occurs, when the paper is used it considerably reduces the negative flashover voltage so that the usual polarity effect disappears. These results are discussed in terms of space-charge fields, which first modify the trajectory of streamers from the point electrode, and secondly initiate a triggering discharge between the plane electrode and the recording paper. - Author(s): A. Petouris ; J. Humphries ; P. Russell ; A. Vourdas ; .R. Jones
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 171 –176
- DOI: 10.1049/ip-smt:19949699
- Type: Article
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p.
171
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Rapid developments in the field of modern optics are already having a major impact upon areas such as communications, sensing, information storage and image processing which have hitherto been the province of the electronic engineer. There is a need for evolving new teaching methods for accelerating the acquisition of relevant optical principles by undergraduate students of electronics from an engineering systems aspect rather than from a conventional physics approach. This contribution describes the development of part of a teaching module for this purpose which involves a combination of computer based methods coupled with practical work to provide experience of optical systems. The module is designed to demonstrate the optical information processing capabilities of a simple optical system through the use of ray optics analysis. It forms part of a unit on optical systems for electronic engineers, the other component of which is a supporting lecture course. - Author(s): M.T. Abulma'atti
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 177 –178
- DOI: 10.1049/ip-smt:19949698
- Type: Article
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p.
177
–178
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An algorithm is presented for calculating the Fourier series coefficients of experimentally obtained waveforms. The implementation of this algorithm requires only simple basic mathematical operations. Application of the algorithm is illustrated with an example. - Author(s): C. Chou
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 179 –184
- DOI: 10.1049/ip-smt:19949767
- Type: Article
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p.
179
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A Fourier aperture (FA) is composed of two sinusoidal gratings in contact. When the two gratings rotate on the same axis in equal angles but opposite directions, a clear pattern of difference moire fringes is formed, the moire frequency depending on the angle between the two gratings. This aperture of moire fringes is used as a variable-frequency grating which is able to scan the object spectrum in the frequency domain. The summation-filtered back projection algorithm with three different apodising functions was introduced in the reconstruction. A99mTc gamma ray source and a 1 inch-diameter NaI scintillation detector were used in the experiment. The thyroid phantom images showed that spatial resolution of FA agrees with the theoretical prediction. Three dimensional image capability is also discussed. The matrix inversion algorithm was used in the computer simulation of 3-D images. Although the depth resolution of a FA is limited by the restricted view angle of the detector, two plane objects free from noise at different depths were reconstructed. - Author(s): A.L. McCarren ; H.J. Ruskin ; K.G. McGuigan ; M.O. Henry
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 185 –189
- DOI: 10.1049/ip-smt:19949936
- Type: Article
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p.
185
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Information from the many kinds of spectroscopy used by chemists and physicists is fundamental to our understanding of the structure of materials. Numerical techniques have an important role to play in the augmentation of the instrumentation and technology available in the laboratory, but are frequently viewed as separate from the laboratory procedures. We describe an integrated PC-based approach for obtaining directly the parameter estimates of transition types in piezo-spectroscopic measurements of crystalline materials. Typically, the analyses in question are required to handle complex secular matrices, to distinguish between components in the experimental results, and to identify the transition types as rapidly and as efficiently as possible. The method described, based on providing a discrete shell to the Powell algorithm, is shown to give both accurate identification of the transition type in the case of new data and improved fits (i.e. reduction in residual variation) when compared with results obtained via standard procedures. In addition it is flexible with respect to the language used and possesses a high degree of portability. We illustrate the success of the approach using (i) data previously reported on the solution of a trigonal defect which includes both mixing of states and spin orbit interactions and (ii) new data obtained for a defect related to beryllium impurities in silicon. - Author(s): P.T. Gaynor and P.S. Bodger
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 190 –196
- DOI: 10.1049/ip-smt:19949851
- Type: Article
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p.
190
–196
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Analysis of the physical, optical and electrical aspects of voltage impulse dielectric breakdown in rubber membrane spheroids shows a spatial organisation of material ionisation, resulting in hole formation. The morphology of this breakdown is much like the dielectric breakdown of a biological cell membrane under electrical impulse conditions, commonly called electropermeabilisation or electroporation. A study of these breakdown systems indicates a possible mechanism of biological electropermeabilisation based on material ionisation. - Author(s): A. Bouziane ; K. Hidaka ; J.E. Jones ; A.R. Rowlands ; M.C. Taplamacioglu ; R.T. Waters
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 197 –204
- DOI: 10.1049/ip-smt:19949930
- Type: Article
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p.
197
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This paper is the first part of a two-part inaugural study into the characteristics of DC corona discharges between circular cylindrical electrodes with parallel axes (a paraxial system). This geometry is intermediate between those of wire plane and coaxial cylindrical systems, which are two limiting cases of practical importance. A review of the literature on these limiting cases is followed by a description of recently developed instrumentation for field and current measurements on the passive outer electrode. Experimental results are reported for positive discharges in ambient air with various overvoltages for fixed diameter electrodes (100 mm and 0.56 mm) and various offsets of the inner electrode. The measurements confirm a quadratic law dependence of total current on voltage which is typical of the limiting cases, and an empirical expression has been developed relating this law to the paraxial offset. The current density at each point on the outer cylinder also shows this quadratic dependence on voltage at all positions and for all offsets. Similarly, the electric field distribution is shown to behave approximately linearly with voltage for all offsets. However, when normalised using their maximum values, both the current and field distributions show a remarkable independence of the overall voltage. These normalised distributions have been shown to be related by a simple power law where the power is independent of the corona wire diameter. The interrelated data of current density and electric field will be used for numerical simulation of corona spatial characteristics in the second part of the study. - Author(s): A. Bouziane ; K. Hidaka ; J.E. Jones ; A.R. Rowlands ; M.C. Tapiamacioglu ; R.T. Waters
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 205 –214
- DOI: 10.1049/ip-smt:19949931
- Type: Article
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p.
205
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For pt.I see ibid., vol.141, p.197-204. The authors deal with the theory, numerical analysis and simulation of positive-corona air discharges in noncoaxial cylinders. A finite-difference method is developed which is then modified for forward extrapolation. Experiments described previously, using various paraxial offsets and voltages, are simulated using the Townsend/Kaptzov field assumption at the inner conductor and adopting a hypothesis for the corona current distribution from various alternatives. Good correlations are found between the measured and calculated current and electric field distributions at the outer cylinder. Calculation errors are carefully assessed. It is found that the Laplacian and Poissonian field shapes are very different and exhibit field-crossover effects. The simulated solution allows an assessment of the Deutsch approximation to be made for this geometry. Variations between the Laplacian and Poissonian fields can differ by an order of magnitude which shows the approximation to be, at best, the starting point for a numerical solution. The finite-difference algorithm developed is quite general and can be adapted to other two-dimensional charge-flow problems. - Author(s): A.S. Sehmi ; N.B. Jones ; S.Q. Wang ; G.H. Loudon
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 215 –223
- DOI: 10.1049/ip-smt:19949933
- Type: Article
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p.
215
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This paper describes expert systems suitable for signal processing and decision support in the interpretation of neuroelectrical signals such as brainstem auditory evoked potentials (BAEP), interference pattern electromyograms (EMG) and electroencephalograms (EEG). These systems are characterised by a significant amount of coupling between numerical and symbolic processing techniques. The BAEP and EMG expert systems incorporate rule-based inference mechanisms with a high degree of uncertain inference using fuzzy logic. The EEG expert system uses an object-oriented approach to capture high-level stereotypes of spatiotemporal concepts in multichannel EEG signals. These stereotypes can trigger lower-level numerical procedures in an opportunistic manner to extract contextual numerical information using a limited form of uncertain inference. A conceptual hardware and software framework for implementing such expert systems is also outlined. - Author(s): D.B. Watson and A.M. Watson
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 224 –228
- DOI: 10.1049/ip-smt:19949919
- Type: Article
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p.
224
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The acceleration of a steel ball running on parallel steel rails has been measured. When the rails are connected, respectively, to the positive and negative terminals of a DC supply, the ball completing and electrical circuit, the acceleration increases as the current is raised. Three components of acceleration have been recognised: a frictional retardation; an electromagnetic acceleration which increases with current but is independent of speed; and an electromagnetic retardation which increases with both current and speed. The characteristics of this linear ball-bearing motor are compared with those of the cylindrical ball-bearing motor, and with the predictions of electromagnetic theories. - Author(s): D.B. Watson ; D.M. Watson ; G.J. Bate
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, p. 229 –232
- DOI: 10.1049/ip-smt:19949928
- Type: Article
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p.
229
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The paper describes experiments aimed at producing movement of small square particles of aluminium and copper. It is shown that the conventional slotted linear induction motor should be avoided as the slot pitch sets a lower limit to the size of particle that can be moved. A simple surface winding was constructed from 0.6 mm diameter enamelled copper wire stretched over a wooden board. Experiments were carried out at 754 Hz using a transient resonant circuit to supply 2-phase currents of peak value 537 A. The transient circuit caused square particles of 1.2 mm side to slide over a short measurable distance. A theoretical expression for the force on the particle is developed. - Author(s): L.R. Arnaut and L.E. Davis
- Source: IEE Proceedings - Science, Measurement and Technology, Volume 141, Issue 3, page: 232 –232
- DOI: 10.1049/ip-smt:19949001
- Type: Article
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Explicit estimation of speech boundaries
Newton-Raphson method for accuracy enhancement of electro-optical targeting system
Location of impact points in the impulse flashover of air from a pointed electrode
Computer aided design for teaching modern optics to electronic engineering undergraduates
Simple method for calculating Fourier coefficients of experimentally obtained waveforms
Fourier coded-aperture imaging in nuclear medicine
Piezo-spectroscopic data analysis: a PC tool
Ionisation of dielectric spheroid membranes: a balloon model of electroporation of biological cells
Paraxial corona discharge. I. Review, instrumentation and experiments
Paraxial corona discharge. II. Simulation and analysis
Knowledge-based systems for neuroelectric signal processing
Linear ball-bearing motor
Surface winding for moving small conducting particles
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