IET Science, Measurement & Technology
Print ISSN
1751-8822
Online ISSN 1751-8830
Online ISSN 1751-8830
IET Science, Measurement & Technology publishes papers in science, engineering and technology underpinning electronic and electrical engineering, nanotechnology and medical instrumentation. Major themes of the journal are electromagnetism including electromagnetic theory, computational electromagnetics and EMC; properties and applications of dielectric, magnetic, magneto-optic, piezoelectric materials down to the nanometre scale; measurement and instrumentation including sensors, actuators, medical instrumentation, fundamentals of measurement including measurement standards, uncertainty, dissemination and calibration.
This publication was previously known as IEE Proceedings - Science, Measurement and Technology 1994-2006. ISSN 1350-2344. more..
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Latest content
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Influence of natural ester on frequency dielectric response of impregnated insulation pressboard
- Author(s): J. Hao; R. Liao; Z. Ma; L. Yang
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p.
403
–411
(9)
It is important to investigate the dielectric behaviour of natural ester-paper insulation, as the number of transformers choosing natural ester as their insulation oil is increasing. A comparative study of the pressboard with different conditions immersed in natural ester and mineral oil was conducted. X–Y model simulation was used to indicate the difference between the frequency-domain spectroscopy characteristics of transformer main insulation system using natural ester-pressboard insulation (NEPI) system and mineral oil-pressboard insulation (MOPI) system, which have the same moisture content or experience the same ageing period. Compared with the MOPI with low moisture content, the NEPI with the same low moisture content has higher ɛ′r and tanδ values in the lower frequency region at various temperatures; although no significant differences exist in the ɛ′r and tanδ curves of these two kinds of oil-impregnated pressboard, when its moisture content is high. The X–Y model simulation results also show that the dielectric loss difference between the NEPI system and the MOPI system with low moisture content is more obvious at higher temperature. Besides, the pressboard aged in natural ester has higher ɛ′r and tanδ values than that aged in mineral oil after ageing for the same time. X–Y model simulation results show that the tanδ values in the lower and middle frequency regions could be used as the ‘fingerprint’ of the ageing condition of the NEPI system and the mineral-oil pressboard insulation system.
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Electrocardiogram compression technique for global system of mobile-based offline telecardiology application for rural clinics in India
- Author(s): M. Mitra; J.N. Bera; R. Gupta
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p.
412
–419
(8)
Compression of Electrocardiographic (ECG) data is an important requirement to develop an efficient telecardiology application. This study describes an offline compression technique, which is implemented for ECG transmission in a global system of mobile (GSM) network for preliminary level evaluation of patient's cardiac condition in a non-critical condition. A short-duration (5–6 beats) ECG data from Massachusetts Institute of Technology–Beth Israel Hospital (MIT–BIH) arrhythmia database is used for the trial. The compression algorithm is based on direct processing of ECG samples in four major steps: viz., down-sampling of dataset, normalising inter-sample differences, grouping for sign and magnitude encoding, zero element compression and finally, conversion of bytes into corresponding 8 bit American standard code for information interchange (ASCII) characters. The developed software at the patient side computer also converts the compressed data file into formatted sequence of short text messages (SMSs). Using a dedicated GSM module these message are delivered to the mobile phone of the remote cardiologist. The received SMSs are to be downloaded at the authors computer for concatenation and decompression to obtain back the original ECG for visual or automated investigation. An average percentage root-mean- squared difference and compression ratio values of 43.54 and 1.73 are obtained, respectively, with MIT–BIH arrhythmia data. The proposed technique is useful for rural clinics in India for preliminary level cardiac investigation.
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High-power calibration and measurement method for bio-electromagnetic study
- Author(s): X. Liu; H.-J. Chen; X. Chen; D. Wen; C. Parini
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p.
420
–426
(7)
A novel method for high-power calibration/measurement is presented in this work. This method employs a coupler and a dipole antenna to achieve high-power measurement. The coupler serves as a low-power sensor, whereas the dipole antenna is responsible for the high-power measurement. This method successfully calibrated a 600 W 13.56 MHz radio frequency generator and is potentially useful for even higher power measurement, as well as for hazardous high-intensity electromagnetic environment measurement, avoiding the use of expensive high-power metres.
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Simulation and energy management of an experimental solar system through adaptive neural networks
- Author(s): R.H. Fouad; M.S. Ashhab; A. Mukattash; S. Idwan
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p.
427
–431
(5)
In this study, the authors consider a solar system which consists of a solar trainer that contains a photovoltaic panel, a DC centrifugal pump, flat plate collectors, storage tank, a flowmeter for measuring the water mass flow rate, pipes, pyranometer for measuring the solar intensity, thermocouples for measuring various system temperatures and wind speed meter. The various efficiencies of the solar system have been predicted by an artificial neural network (ANN) which was trained with historical data. The ANN fails to predict the efficiencies accurately over the long-time horizon because of system parts degradation, environmental variations, date changes within the year from the modelling date and presence of modelling errors. Therefore the ANN is adapted using the error between the ANN-predicted efficiency and the efficiency measurement from the appropriately selected sensors and efficiency laws to update the network's parameters recursively. The adaptation scheme can be performed online or occasionally and is based on the Kaczmarz's algorithm. The adaptive ANN capability is demonstrated through computer simulation.
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E-Science application of wireless sensor networks in eco-hydrological monitoring in the Heihe River basin, China
- Author(s): L. Luo; Y. Zhang; W. Zhu
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p.
432
–439
(8)
In order to monitor the eco-hydrological processes of the Heihe River basin, obtain spatially dense measures, determine the energy conversion rules and detailed characteristics of material migration within a small-scale system, a wireless sensor network (WSN) with a 4×4 grid was deployed in the basin. It is difficult to deploy and maintain a WSN system, especially in the study area of the Heihe River basin where harsh weather conditions and treacherous terrain can compromise the performance of such a system, while at the same time, high-energy efficiency, reliable delivery and high-quality measurements are required. To increase reliability under these conditions, protective and redundancy measures were utilised in the deployment. These nodes are now installed to collect data and transmit them through several repeaters to the base station in the experimental research establishment, where the data are automatically transmitted to the server in the establishment, and finally transferred to supercomputers in our institute through an optical fibre channel, thus achieving complete automated online data storage, analysis and real-time display. The monitoring of the Heihe River basin via WSN has now enriched field observation capabilities, and will create an e-Science application for eco-hydrological research.
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Application of the Hilbert–Huang transform with fractal feature enhancement on partial discharge recognition of power cable joints
- Author(s): F.-C. Gu; H.-C. Chang; F.-H. Chen; C.-C. Kuo; C.-H. Hsu
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p.
440
–448
(9)
This study proposes a novel method of partial discharge (PD) pattern recognition based on the Hilbert–Huang transform (HHT) with fractal feature enhancement. First, this study establishes three common defect types with one blank sample of 25 kV cross-linked polyethylene (XLPE) power cable joints and uses a commercial acoustic emission sensor to measure the acoustic signals caused by the PD phenomenon. The HHT can represent instantaneous frequency components through empirical mode decomposition, and then transform to a 3D Hilbert energy spectrum. Finally, this study extracts the fractal theory feature parameters from the 3D energy spectrum by using a neural network for PD recognition. To demonstrate the effectiveness of the proposed method, this study investigates its identification ability using 120 sets of field-tested PD patterns generated by XLPE power cable joints. Unlike the fractal features extracted from traditional 3D PD images, the proposed method can separate different defect types easily and shows good tolerance to random noise.
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Detection of cardiac arrhythmic beats by logical classifier using binary coding
- Author(s): S. Pal; M. Mitra
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p.
449
–455
(7)
Cardiac arrhythmia is a rhythmic disorder in heart generated from problems in impulse formation or conduction. Automatic detection of arrhythmia at the time of its occurrence is very essential for continuous cardiac monitoring. As different kinds of arrhythmias produce different morphology of beats, it is difficult to suggest one typical algorithm to classify all kind of arrhythmic beats. In this work, a binary logical classifier is proposed to identify beats such as premature ventricular contraction, bundle branch block, paced and normal. In most of the arrhythmic beats the wave texture is modified along with a change in temporal information. The proposed logical classification requires binary coding of beats based on temporal and morphological features to form a binary array representing the status or signature of the beat. Next the classification is made by the status of the bits depending upon its position in the binary array. This approach of logical classification reduces the complexity of detection because of its binary nature resulting in fast and ready reference of arrhythmic disorder for standalone systems. Performance evaluation results indicate that the method has good accuracy, sensitivity and positive predictivity for all kind of test beats. Moreover, this technique is easily hardware implementable because of its binary nature.
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Robust feature extraction from impedimetric signals using wavelet packet decomposition with application to cytotoxicity testing
- Author(s): Y. Abdul Djawad; J. Kiely; M. Nibouche; P. Wraith; R. Luxton
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p.
456
–463
(8)
Impedance-based cytotoxicity testing provides a simple, real-time and non-invasive assay technique that interferes minimally with cell morphology and function. In this study, impedimetric measurements of ECV304 cells with increasing concentrations of hydrogen peroxide were performed over 3 h, using D sensor connected to a lock-in amplifier at frequencies between 200 and 830 kHz. The output signals were analysed and decomposed using a two-level wavelet packet decomposition to obtain low- and higher-frequency coefficients of each signal. Subsequently, the sum of the negative and positive values and the difference values of each sub-band were calculated to acquire features of the signal coefficients. The patterns of features were compared with the microscopy images showing morphological changes of the cells for the four hydrogen peroxide concentrations and correlations between the extracted features and the morphological changes were identified. This demonstrated that wavelet packet decomposition was an effective feature extraction technique, which could provide a robust input vector for toxin clustering and classification purposes.
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Effects of model complexity and tissue anisotropic conductivity on cortical modulation during transcranial direct current stimulation
- Author(s): S. Shahid; P. Wen; T. Ahfock
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p.
464
–473
(10)
An anatomically accurate high-resolution finite-element head model and its derivatives have been employed to examine the influence of subcutaneous fat and muscle tissues on cortical modulation. The effects of skull, muscle and white matter (WM) directional conductivity have also been investigated. Results indicate that the inclusion of additional tissues in the head model have a profound effect on the magnitude and distribution pattern of induced current density. Similarly, anisotropic tissue conductivity caused a significant deterioration in spatial focality of cortical currents along with a more distorted and diffused distribution pattern across the cortex.
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Comparison of partial discharge characteristics and degradation in several polymeric insulators
- Author(s): D. Adhikari; D.M. Hepburn; B.G. Stewart
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p.
474
–484
(11)
Polymeric insulating materials with excellent electrical properties are widely used in electrical power equipment. These materials are degraded, however, when they are subjected to partial discharge (PD) with different polymeric materials possessing different levels of PD resistance. In this study the PD characteristics and degradation caused by PD are analysed and compared for four different polymers – poly(ether sulphone) (PES), poly(ethylene terephthalate) (PET), poly(propylene) (PP) and low-density poly(ethylene) (LDPE). An artificial void is created in each of the polymer samples and electrically stressed above PD inception voltage (PDIV) for 4 h. The simulated electric field distribution inside the void for each of the polymer materials at the respective PDIVs is modelled using COMSOL to validate the experimental results. Little work has correlated void PD characteristics with material degradation induced by PD across a range of different polymers and subsequently categorised them according to their PD resistances. This study therefore presents a comparative study of the N–Q patterns of PD pulses (a plot of the number of discharges against the measure of apparent charge), PD repetition rate and the chemical and morphological changes occurring on the void surfaces for each type of polymer. The results show that the PD resistance of these four polymers can be categorised in a decreasing order according to the following sequence: LDPE, PP, PET and PES with LDPE being most resistant to PD and PES the least resistant.
