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IET science, measurement & technology
IET
IET science, measurement & technology

IET

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1751-8822

IET science, measurement & technology/Journal IET science, measurement & technology
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    Evaluation of vibration measurements on human face using median and maximum frequencies

    Umit Ak, MehmetBilgin, SuleymanOral, OkanFeza Carlak, Hamza...
    853-856页
    查看更多>>摘要：There are some studies in the literature in order to make the interpretation of human tissues having different characteristics. Some of these studies focused on the evaluation of human face tissues. Vibration signals generated from vocal cords have been used in these studies about human face tissues. However, any study using the vibration signals recorded by applying the external vibration source having fixed frequency value is not available in the literature. In this study, it is aimed to investigate the frequency characteristics of the vibration signals recorded from the human face. These signals obtained from nine different regions on the faces of subjects are analysed using frequency characteristics. In the analysis stage, median and maximum frequency values are calculated and evaluated. So, the softness and hardness interpretation about these regions on the face can be made and the frequency ranges of these regions can be determined. As a result, it is observed that low-frequency signals are dominant in hard regions and high-frequency signals are dominant in soft regions.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Statistical correlation technique for transient signal analysis during impulse testing of transformers

    Garg, AnkitaSharma, TapanJain, ApurtiVelandy, Jeyabalan...
    857-863页
    查看更多>>摘要：The reliable technique for identification of winding insulation faults in a transformer is necessary for a testing engineer during impulse test. In this study, a statistical correlation technique is proposed to estimate the 'best correlation' between transient signals for passed (withstood the impulse voltage) or failed (not withstood) conditions of the insulations. In this study, normalised reduced impulse voltage is considered initially as a reference signal. The next successive impulse test sequences due to rated test voltage are correlated as a test signal with a reference signal using a proposed technique. It makes a 'good correlation value along with its directions' between the reference signal and test signal based on measured the applied impulse voltage waveshape and its winding response. The fundamentals of the correlation coefficient, curve fitting techniques, conditional variance, normalisation and time delay index are integrated effectively to predict the characteristics (degree/magnitude and direction) of correlation between the signals. 2.5-MVA 11/0.433 kV (distribution transformer), 0.3-MVA 34.5/0.415 kV (earthing transformer) and 250-MVA 500/275/33 kV (power transformer) are effectively utilised to validate proposed technique. The advantage of the proposed technique is validated with partial discharge detection in windings due to an impulse voltage application using an 11 kV single-layer winding.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    GIS partial discharge pattern recognition via lightweight convolutional neural network in the ubiquitous power internet of things context

    Wang, YanxinYan, JingYang, ZhouZhao, Yiming...
    864-871页
    查看更多>>摘要：The construction of the ubiquitous power internet of things (UPIoT) provides a new feasible solution for gas-insulated switchgear (GIS) online monitoring and fault diagnosis, but it also puts forward greater requirements for time and accuracy. How to find an effective real-time model that can be applied to the UPIoT mobile terminals has become an urgent problem needing to be solved. To this end, this study proposes a lightweight convolutional neural network (LCNN) for GIS partial discharge (PD) pattern recognition using three lightweight convolutional blocks, and introduces the lowest recognition accuracy of single-class faults as the primary indicator for selecting the optimal model under the UPIoT. First, three lightweight convolutional blocks are introduced for constructing an LCNN. Then, the optimal model constructed by the lightweight blocks is sought. Next, criteria for determining the best model are introduced, and the best model under the UPIoT is selected. This study provides a reference standard for the construction of GIS PD pattern recognition under the UPIoT. Meanwhile, through the balance of evaluation indicators, this study verifies that the minimum recognition accuracy of the MnasNet model is 98.8%, which is obviously better than other methods and lays a solid foundation for GIS PD pattern recognition.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Lightning impulse breakdown path and characteristics with dielectric BMC barrier inserted sphere-plane electrode

    Seok, Bok-YeolChoi, Won
    872-876页
    查看更多>>摘要：This study deals with the electrical breakdown characteristics of the sphere-plane electrode system with the dielectric barrier of bulk moulding compound (BMC) material under the positive lightning impulse voltage. The sphere electrode has a spherical shape of 50 mm in diameter and suspended with a metal rod of 10 mm in diameter, while the plane electrode has a circular with a diameter of 350 mm. The dielectric barrier has a square plate shape of BMC material, and the dimension is changed from 80 x 80 to 240 x 240 mm(2). Experimental results show that electrical breakdown paths could be identified into three categories, depending on the dielectric barrier position and the dimension. The larger and farther away from the sphere electrode the dimension of the dielectric barrier is, the occurrence probability of electrical breakdown through the penetration of dielectric barrier becomes. It was confirmed that the breakdown voltage considerably depends on the dimension of the dielectric barrier and the dielectric barrier position.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Calibrated non-contact vibrational harmonics measurement based on self-vibration compensated 2D-PSD with MEMS accelerometer using FFT analysis

    Das, SampaSaha, ArdhenduSujith Kumar, Chanda
    877-882页
    查看更多>>摘要：This study presents a novel fast Fourier transform (FFT)-based non-contact vibrational harmonics measurement system using a position sensitive detector (PSD) along with calibration using a piezoelectric accelerometer. Frequency-domain vibrational analysis is required as the changes in machine dynamics are directly related to its failures and could provide more insight into the vibration signal. In this regard, FFT is used for spectral analysis to detect the harmonics in the vibration signal. The novelty of the applied technique for detecting vibrational harmonics lies in its innate contactless nature where the vibration detection sensor i.e. PSD is placed at a particular distance from the vibrating target. Additionally, the parasitic and external vibrations, which might pose unforeseen errors in the detected vibration data, have been nullified by employing a self-vibration technique using an ADXL-345 three-axis accelerometer. The results obtained through PSD have been calibrated via a standard Bruel & Kjaer (B & K) vibration measurement system which uses a piezoelectric accelerometer (B & K accelerometer). The proposed measurement technique is equipped with NI compact RIO-9074 that features a real-time processor and an FPGA. The system was observed to effectively measure the frequency range 5-600 Hz with a maximum relative error of 2% in FFT amplitudes.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Theoretical and experimental investigation of six-degree-of-freedom force/thrust measurement stand

    Jun, ZhangAkbar, Muhammad AyazXin Lei, WangYi Hua, Chen...
    883-890页
    查看更多>>摘要：Thrust testing units with a piezoelectric dynamometer have unique traits such as excessive stiffness, tremendous measurement accuracy, dynamic performance and no hysteresis. These are widely used in the applications requiring force/thrust measurements in the aerospace industry and high-end tool condition monitoring. The performance of these units is necessary to be evaluated. In this study, an improved layout of six-degree of freedom force/thrust measurement stand is proposed and analysed theoretically and experimentally. The measurement stand is a structural component to measure six components of force, such as axial force/thrust (F-X,F-Y, andF(Z)) and other components (M-X,M-Y, andM(Z)). Test stand consists of seven piezoelectric sensors in two sections. The front part consists of four piezoelectric force sensors, while the rear part consists of three sensors. The rear section is hexagonal, with three sensors mounted at 120 degrees. The measurement stand can measure the principal force/thrust up to 50,000 N. A mathematical model is derived for every sensor against forces in all directions. To calibrate the stand, a calibration platform is designed and fabricated. The calibration platform can generate a range of forces/moments. Calibration experiments verifies that the measurement stand is fairly functional to measure variety of forces/moments with high repeatability.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Temporal and spatial characteristics of soluble salt components accreted on the insulator surface

    Cao, BinZhao, ChenglongYin, FanghuiWang, Liming...
    891-896页
    查看更多>>摘要：Due to the differences in typical pollution sources, the soluble salt composition deposited on the naturally contaminated insulators varies with the region. As different soluble salts have different effects on the pollution flashover voltage of insulators, it is necessary to investigate the spatial and temporal distribution of the soluble salt composition deposited on the insulator surface to make the external insulation design more scientifically and reasonably. In this study, an artificial contamination test platform was built to collect the contamination naturally deposited on the specimens. The test results showed that the contamination composition deposited on the specimen was similar to that in the atmosphere, and the inclination angle of the specimen and the duration of pollution deposition had little influence on the contamination composition. After examining the industrial post insulators from actual substations, it was found that the contamination composition was almost the same for different insulator surface materials, insulator shed types, and voltage polarities. It was also found that the deposited contamination was mostly influenced by pollution sources. The results can provide a reference for the studies of pollution distribution of natural insulators.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Efficient analytical method for the shielding effectiveness of an apertured enclosure based on the BLT equation

    Gong, YanfeiLi, YujieJiang, Luhang
    897-904页
    查看更多>>摘要：An efficient analytical method based on the Baum-Liu-Tesche (BLT) equation has been developed for predicting the shielding effectiveness (SE) of an apertured enclosure excited by an external plane wave. First, the equivalent circuit and the signal flow graph are constructed, which helps understand the energy transmission of the enclosure. Then, the SE is obtained by using the generalised BLT equation, and the proposed analytical method is employed to analyse the effect of various parameters on the SE. Finally, the analytical method is extended to handle the enclosure with an aperture array, an enclosure with apertures at the opposing walls and two cascaded enclosures. The analytical method has been successfully verified by the CST over a wide frequency band of 0-3.0 GHz, which consumes less time than conventional numerical methods. Besides, whatever the condition of the enclosure or the aperture is, the analytical method can predict the SE and higher-order modes at higher frequencies accurately.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    Time-domain resonant characteristics between the disturbances and the RS422 communication signals in Tesla pulse driver, and analysis on the caused RS422 communication interference

    Zhang, YuCheng, JieSu, JiancangZheng, Lei...
    905-913页
    查看更多>>摘要：The communication circuit network is widely employed for signal transmission in high-voltage pulse driver system, for commanding, controlling, measurement & communication. The electromagnetic compatibility of the communication circuit network mainly decides the stability and reliability of the high-voltage pulse driver system. Aiming at the electromagnetic interference (EMI) problems of the RS422 communication circuit in the Tesla pulse driver, the generated disturbance sources and characteristics from the Tesla pulse driver itself are analysed in five divided work stages, and two typical simplified EMI coupling modes for the communication circuit are also presented in this Letter. In the RS422 communication cable circuits between the subsystems of the pulse driver, the time-domain resonant characteristics of the communication signal and the conducting disturbances are analysed. The error and failure modes of the RS422 communication data caused by the full time-domain conducting interference are also revealed. Evaluation and calculation method for the time-domain resonant probability and the interference probability of the RS422 communication signals is also put forward. The communication interference probability is also calculated under different repetition work modes of the Tesla pulse driver. In view of the time-domain resonance phenomenon, some effective ways for time-domain resonance elimination and interference compression are put forward.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet

    3D Modelling and simulation analysis of electric field under HV overhead line using improved optimisation method

    Djekidel, RabahBessedik, Sid AhmedAkef, Samar
    914-923页
    查看更多>>摘要：This study proposes a three-dimensional (3D) quasi-static modelling of the electric field produced by high voltage (HV) overhead power lines using charge simulation method combined with intelligent optimisation algorithms, such as particle swarm optimisation, genetic algorithm and grey Wolf optimiser (GWO), to find the optimal values of parameters for an accurate calculation. Results show that the GWO works better than other algorithms. Several parameters affecting the electric field have been studied; it is observed that taking into account the effect of the exact catenary curve of the power line conductors is much more interesting particularly at the mid-span level where the electric field becomes very significant. According to these values, the limits set by the International Commission on Non-Ionising Radiation Protection guidelines for electric field strength are met for occupational and public exposure. The simulation results are compared with those obtained by the 3D Integration method, a fairly good agreement is found. To confirm the performance and effectiveness of the proposed method, the results obtained are also verified with measurement values available in the literature, a good similarity is achieved.
      原文链接:
    • NETL
    • NSTL
    • Inst Engineering Technology-Iet