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Science, Measurement & Technology, IET

Issue 5 • Date Sept. 2007

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Displaying Results 1 - 11 of 11
  • Investigations on voltages and currents in the lightning protection system of the Indian satellite launch pad-I during a stroke interception

    Publication Year: 2007 , Page(s): 225 - 231
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (295 KB)  

    A reliable protection against direct lightning hit is very essential for satellite launch pads. In view of this, suitable protection systems are generally employed. The evaluation of efficacy of the lightning protection schemes among others requires an accurate knowledge of the consequential potential rise at the struck point and the current injected into soil at the earth termination. The present work has made a detailed effort to deduce these quantities for the lightning protection scheme of the Indian satellite launch pad-I. A reduced scale model of the system with a frequency domain approach is employed for the experimental study. For further validation of the experimental approach, numerical simulations using numerical electromagnetic code-2 are also carried out on schemes involving single tower. The study results on the protection system show that the present design is quite safe with regard to top potential rise. It is shown that by connecting ground wires to the tower, its base current and, hence, the soil potential rise can be reduced. An evaluation of an alternate design philosophy involving insulated mast scheme is also made. The potential rise in that design is quantified and the possibility of a flashover to supporting tower is briefly looked into. The supporting tower is shown to have significant induced currents. View full abstract»

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  • Ill-posed waveguide discontinuity problem involving metamaterials with impedance boundary conditions on the two ports

    Publication Year: 2007 , Page(s): 232 - 239
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    It is shown that the presence of double negative metamaterials can affect the traditional well posedness of time-harmonic electromagnetic boundary value problems, even when absorbing boundary conditions are considered on part of the boundary. This is done by considering a simple waveguide discontinuity problem with traditional impedance boundary conditions on the two ports. The theoretical results are then used to introduce some doubts on the reliability of models with sharp interfaces between lossless double positive and double negative materials, when the latter are constructed with arrangements of normal materials; and to explain the anomalous behaviour of many numerical simulators when double negative metamaterials are involved. View full abstract»

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  • Enhancement of accuracy for measuring the susceptibility of integrated circuits to conducted electromagnetic disturbances

    Publication Year: 2007 , Page(s): 240 - 244
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (391 KB)  

    An original and reliable prototype injection setup has been developed in order to carry out accurate conducted susceptibility measurements up to 1.5 GHz. The prototype has been proposed as an alternative solution to typical injection setups such as a coupling capacitor, bias tee or cross-talk system, frequently used with the direct power injection standard IEC62132-4. Simple to build and mechanically sound, the prototype injection setup is used to merge continuous conducted electromagnetic disturbances with wanted signals by using merely a semi-rigid coaxial cable. It offers good stability on a wide frequency range. Furthermore, it is neither expensive nor complicated to build. View full abstract»

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  • Detection and localisation of magnetic objects

    Publication Year: 2007 , Page(s): 245 - 254
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    Detection and localisation of hidden magnetic objects is studied. The concomitant disturbance of the earth magnetic field is exploited. Magnetic fields and or gradients are measured with a number of sensors. Two point models for magnetic fields are selected for the analysis: the magnetic dipole and its quadrupole extension. It is shown how to apply least squares analysis of the data in order to detect and localise magnetised objects. The theoretical framework is tested in simulations, including noise. Two methods to do the minimisation are chosen. The formalism performs well in the simulations. Detection and localisation of the model objects is successful. No decisive differences in performance of the two minimisation methods are found. Results for the position parameters are reliable in any case. We have evaluated the goodness of fit in our simulations. Theoretical and simulated chi-square distributions are compared for different fit models and noise distributions with satisfactory results. The obtained parameter distributions are Gaussian. Measurements are performed to test the algorithms on real data collected for three ferromagnetic objects: a magnet, pipe and block. The magnet is easily localised, the pipe reasonably well. The block cannot be localised: its field variations cannot be distinguished from background field variations. Subsequent simulations show that using gradiometers improves the performances of the algorithms. The effects of a number of controllable parameters are evaluated. View full abstract»

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  • Efficient image enhancement algorithm for images of steel reinforcing bars in concrete obtained by a new solid-state sensor-based system

    Publication Year: 2007 , Page(s): 255 - 260
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (493 KB)  

    This work describes a new image-processing method capable of enhancing the raw images of steel reinforcing bars in concrete obtained by a new generation of imaging instrument based on solid-state magneto-inductive (MI) sensors. The new method considers the non-uniform response of the static search coil and addresses the problem of image blurring because of the field distribution pattern and bar depth. Experimental results obtained for different steel bar specimens are presented showing a significant enhancement of the original image information regarding bar mesh position and contrast. View full abstract»

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  • Development of an artificial neural network software tool for the assessment of the electromagnetic field radiating by electrostatic discharges

    Publication Year: 2007 , Page(s): 261 - 269
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (541 KB)  

    Artificial neural networks (ANNs) are addressed in order to assess the electric and magnetic field radiating by electrostatic discharges (ESDs). Actual input and output data collected from hundreds of measurements carried out in the high voltage laboratory of the National Technical University of Athens are used in the training, validation and testing process. The developed ANN method is coded in a comprehensive software tool to be used by laboratories involved in ESD tests, which either face a lack of suitable measuring equipment or want to compare their own measurements. The electromagnetic field produced by radiating ESDs, can be assessed very easily and accurately by simply measuring and providing to the tool the discharge current. The authors strongly believe that the proposed ANN software tool can be extremely useful for laboratories involved in ESD tests according to the current IEC Standard, as the forthcoming revised version of this standard will almost certainly include measurements of the radiating electromagnetic field during the verification of ESD generators. View full abstract»

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  • Paramagnetic particle detection for use with an immunoassay based biosensor

    Publication Year: 2007 , Page(s): 270 - 275
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (195 KB)  

    A biosensor and detection system that can provide measurement of analyte concentration within a test sample in four minutes is presented. The biosensor uses an immunoassay with micrometre-sized paramagnetic particle (PMP) labels for quantification. An immunoassay relies on the specific interaction between an antigen (analyte) and the corresponding antibody to immobilise the antigen to a substrate for measurement. In this system, the test samples and PMP labels are added to a reaction vessel on the biosensor and are attracted to a reaction surface at the base of the vessel using an electromagnet, where specific binding takes place. Unlike other immunoassay systems no extra washing or processing procedures are required. The bound labels, and associated antigen are detected, in situ, using a detector coil on the surface of the biosensor. The incorporation of a second coil under the biosensor allows for compensation for environmental changes such as thermal drift. The measurement of the resonant frequency of the detector coil in a parallel resonant circuit, prior to and after addition of the sample, provides a measure of the antigen in the sample. Good frequency stability is provided by the use of a phase locked loop arrangement. The resulting sensitivity was 1.17 mug of PMP labels per 1 Hz of frequency change and the minimum mass of PMPs detected was 62.5 mug. To demonstrate the utility of the technology and the rapidity of measurement, a model immunoassay for Troponin I (a cardiac marker) was used and discrimination at the clinically relevant value of 0.5 ng/ml Troponin I was achieved. View full abstract»

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  • Moisture ingress into low voltage oil-impregnatedpaper insulated distribution cables

    Publication Year: 2007 , Page(s): 276 - 283
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (686 KB)  

    Investigations into the effect of moisture on the degradation of oil-impregnated-paper (OIP) insulated low voltage cables have shown that moisture ingress plays a key role in cable failure, and that the ionic content of the moisture is critical. Here moisture ingress into OIP insulated cable is studied in the laboratory. Experiments have been performed in which cable samples have been exposed to moisture for varying periods, allowing the progress of moisture diffusion within the insulation to be studied. Karl-Fischer titration and observation of dye movement have been used to measure moisture transport. Moisture within a 'wet cable' is shown to be non- uniformly distributed within a sector-shaped core, and dependent on the temperature of the cable. Measurements of insulation conductivity are presented illustrating the resulting macroscopic changes to insulation properties for comparison. An increased rate of penetration of moisture into the cable core results at elevated temperatures, whereas saturation levels are reduced. View full abstract»

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  • Electrical model for power losses in direct power injection

    Publication Year: 2007 , Page(s): 284 - 289
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (707 KB)  

    This paper introduces a study of power losses in a populated board under direct power injection (DPI), used to measure the immunity of integrated circuits to conducted continuous-wave interference. The relative contributions of all loss sources are evaluated, leading to the preeminence of conductive and dielectric losses over radiated ones, and an electrical model of these losses is then suggested. The relationship between losses and impedance profiles is also explained. The validity of the hypotheses formulated in this study is asserted through measurements of radiated losses in a Gigahertz Transverse ElectroMagnetic (GTEM) cell, as well as electrical simulations of a DPI experiment compared with measurements. View full abstract»

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  • Novel Gaussian quantum-behaved particle swarm optimiser applied to electromagnetic design

    Publication Year: 2007 , Page(s): 290 - 294
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (127 KB)  

    Design of global optimisation approaches inspired by swarm intelligence is an emergent research area with population and evolution characteristics similar to those of evolutionary algorithms. However, the swarm intelligence concept differs in that it emphasises co-operative behaviour among group members. Particle swarm optimisation (PSO) is a population-based swarm intelligence algorithm driven by the simulation of a social psychological metaphor instead of survival of the fittest individual. Inspired by the classical PSO method and quantum mechanics theories, this work presents a novel quantum-behaved PSO (QPSO) approach using mutation operator with Gaussian probability distribution, called G-QPSO. The simulation results demonstrate good performance of the QPSO and G-QPSO in solving a significant benchmark problem in electromagnetic area, the shape design of Loney's solenoid benchmark problem. View full abstract»

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  • Probes for spot measurement of surface conductivity on polluted insulators

    Publication Year: 2007 , Page(s): 295 - 300
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (137 KB)  

    The surface conductivity of insulators in the field is often non-uniformly distributed. In this case the integral surface conductivity is not an appropriate parameter of pollution severity. A better evaluation can be achieved on the basis of local conductivity measurements by means of special probes, for example, the rod probe or tissue strip probe. In this work the form factors of different probes are given and the form factor for the rod probe was calculated. The influence of wet-contamination area, the meniscus and the pollution layer thickness on the measured value of surface conductivity are shown. It was found that the surface conductivity on polluted silicone rubber measured by a tissue strip probe is proportional to the equivalent contamination deposit density (ECDD). View full abstract»

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IET Science, Measurement & Technology publishes papers in science, engineering and technology underpinning electronic and electrical engineering, nanotechnology and medical instrumentation.

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