Online ISSN
1751-8830
Print ISSN
1751-8822
IET Science, Measurement & Technology
Volume 1, Issue 4, July 2007
Volumes & issues:
Volume 1, Issue 4
July 2007
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- Author(s): M. Abdel-Salam ; N.L. Allen ; I. Cotton
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 179 –184
- DOI: 10.1049/iet-smt:20050088
- Type: Article
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p.
179
–184
(6)
A method is proposed for computing the inception voltage and time of the corona in air in rod–plane gaps under a positive switching impulse and ramp-shaped voltages. The method is based on the rate of natural production of free electrons in the atmosphere as a result of cosmic ray activity, local radioactivity or ultraviolet radiation from the sun. The computed inception voltages agree reasonably with those measured experimentally for different values of the steepness of the applied switching impulse and ramp-shaped voltages and also with those measured experimentally for a rod gap stressed by a switching impulse voltage. The method is applied to different rod-plane gaps with varying rod radius and gap spacing. - Author(s): Z.F. Zhou ; P. Cai ; R.X. Chen
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 185 –190
- DOI: 10.1049/iet-smt:20060052
- Type: Article
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p.
185
–190
(6)
Dynamic tire forces are the main factor that influences the axle weight measurement accuracy. A nonlinear curve-fitting method is proposed to reduce the influence of the dynamic tire forces. After a brief introduction on the distinction between high-speed and weigh-in-motion low-speed weigh-in-motion and an analysis on the characteristic of the axle weight signal, the algorithm of the nonlinear curve-fitting and its implementation is presented in detail. Finally, the numerical simulation and field experiments are conducted to evaluate the performance of the proposed method. The results of simulation and field experiments prove the effectiveness of the proposed method. The maximum weighing errors of the front axle, the rear axle and the gross weights are 4.01%, 5.24% and 3.92%, respectively, at the speed of 15 km/h or lower. - Author(s): I. Yatchev and A. Alexandrov
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 191 –195
- DOI: 10.1049/iet-smt:20060055
- Type: Article
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p.
191
–195
(5)
An approach using indirect boundary integral equation method is proposed to determine the permeance between ferromagnetic poles in axisymmetric and three-dimensional magnetic systems. A generalised mathematical model is given for both types of magnetic systems. It consists of Fredholm integral equations of the first kind with respect to fictitious magnetic charge density sought in the form of simple layer potential. The system of boundary integral equations is solved using the method of mechanical quadratures. The approach is implemented in its own computer code. Results are presented for axisymmetric poles of electromagnets (cylinders, cones and frustum cones) and for a three-dimensional clapper-type system. Comparisons with known formulas are made and their accuracies are estimated. The approach presented is useful at the stage of preliminary design of magnetic systems. It is also applicable to computation of capacitances and electrical conductances. - Author(s): K.C. Hari ; M. Nabi ; S.V. Kulkarni
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 196 –200
- DOI: 10.1049/iet-smt:20060069
- Type: Article
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p.
196
–200
(5)
In-line inspection of ferromagnetic gas or oil pipe lines having pipe wall defects is typically accomplished using magnetic flux leakage (MFL) technique. An efficient modelling and computational scheme for forward model, during the process of solving inverse problems in magnetostatic non-destructive evaluation using finite-element method is presented. The shape, size and place of defect are determined considering the nonlinearity of the pipe material using genetic algorithm as the optimisation technique. It is shown that the reduced model improves the FE computations significantly. The methodology for construction of defect shapes from particular MFL signals has been explained. - Author(s): G. Antonini
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 201 –209
- DOI: 10.1049/iet-smt:20050047
- Type: Article
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p.
201
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(9)
As feature size of electronic devices decreases, fast and accurate capacitance extraction has become increasingly critical for verification and analysis as regard as electromagnetic compatibility and signal integrity issues. The partial element equivalent circuit method is implemented for three-dimensional capacitance extraction of interconnects and very large-scale integration circuits with multiple dielectrics. The electric field coupling due to free and bound charges are analysed and modelled separately thus allowing to distinguish their contribution. The proposed approach provides physical insight, totally compatible fast methods for accelerating matrix–vector products, allows an easy treatment of lossy and dispersive dielectrics and is well suited for applying model order reduction techniques. - Author(s): N.L. Allen ; M. Abdel-Salam ; I. Cotton
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 210 –215
- DOI: 10.1049/iet-smt:20060106
- Type: Article
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p.
210
–215
(6)
Measurements are reported of breakdown voltage values and pre-breakdown voltage–current characteristics as a function of air density in a simple rod–plane electrode gap 50 mm in length. Pressure has been reduced and temperature raised from normal atmospheric values, independently of each other, to give the relative air densities in a common range less than unity. The effects of different diameters of rod have been studied. The results allow a comparison of the characteristics at equal relative air densities attained by either pressure or temperature adjustment. It is shown that at common relative air densities, breakdown is temperature- and geometry-dependent and that there is a temperature dependence of the pre-breakdown glow currents. The density-dependent relationship between the pre-breakdown glow discharge currents and breakdown voltages is discussed. - Author(s): A. Martinez Olmos ; J. Alberdi Primicia ; J.L. Fernandez Marron
- Source: IET Science, Measurement & Technology, Volume 1, Issue 4, p. 216 –223
- DOI: 10.1049/iet-smt:20060108
- Type: Article
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p.
216
–223
(8)
The resolution and sensing field of electrical capacitance tomography sensors depends upon the configuration of their electrodes and guards, so optimum design is essential in order to provide improved response. Simulations in 2D and 3D are performed based on the finite element method to study the influence of the electrode, guard size and screen arrangement on the sensor characteristics and the reconstructed image.
Computation of inception voltage and inception time of positive impulse corona in rod–plane gaps
Estimating the axle weight of vehicle in motion based on nonlinear curve-fitting
Permeance computation using indirect boundary integral equation method
Improved FEM model for defect-shape construction from MFL signal by using genetic algorithm
PEEC capacitance extraction of 3-D interconnects
Effects of temperature and pressure change on positive corona and sparkover under direct voltage in short airgaps
Simulation design of electrical capacitance tomography sensors
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