The short-circuit withstanding performance of busbar system is one of the most important safety indexes for low-voltage (LV) switchgear. The resonance characteristics, short-circuit displacement, and stress concentration of four typical busbar system arrangements are numerically analysed in this study. First, modal analysis is used to calculate the vibration modes and natural frequencies of the busbar systems. The influence of span length and phase-to-phase distance is discussed and thresholds for resonance prevention are given. Then, electromagnetic-structural coupled models are built to simulate the short-circuit mechanical response. The time-varying displacement and stress are obtained and the dynamic stability of typical arrangements is compared. The proposed results can provide theoretical reference for the dynamic stability design of busbar system in LV switchgear.

Wireless capsule endoscope (WCE) is a new diagnostic device that can be utilised for evaluating the whole digestive tract if effectively actuated. In this research, a new one degree of freedom (1DOF) actuation system based on a magnetic levitation concept is proposed for the capsule endoscope navigation system. The proposed system is used to move a permanent magnet inserted in WCE body by an arrangement of the current controlled electromagnetic actuator placed on a 3DOF movable frame. The aim of this study is to design a proportional–integral–derivative (PID) controller to suspend the capsule and keep it at a demand test region. DC and AC magnetic field-based positioning systems using the Hall effect sensor and the coil sensor, respectively are used to provide the controller by capsule position feedback. Improvement of the position feedback accuracy based on AC magnetic field using discrete Fourier transform is presented. Realistic simulation design of the system is implemented using Matlab/Simulink environment to validate the PID controller. The navigation scheme is implemented practically utilszing digital signal processor to verify the effectiveness of the controller. Finally, simulation and experimental results of the capsule navigation system are presented to show the performance of the proposed controller.

Integration of global navigation satellite system (GNSS) and strap-down inertial navigation system (SINS) in pseudo-range and pseudo-range rate measurements level has been demonstrated as an effective way to provide more reliable navigation solutions. Under this condition, the dimension of measurements matrix of the integration filter increases dramatically along with more GNSSs included in the integration, traditional centralized integration filter processing method cannot address the computational load well. In this study, a distributed integration filter processing method is proposed for the integration of multiple GNSSs and SINS using the pseudo-range and pseudo-range rates as the measurements. Measurement difference inner a same satellite constellation is conducted to remove the clock related variables, which reduces the dimension of the state vector. Secondly, a federated Kalman filter is employed to obtain global optimal estimation of the state variables, which reduces the measurement vector dimension. Mathematical model of the distributed processing model with the simplified integration filter scheme is given in detail. Through the simulation based on a dynamic trajectory, the performance of the proposed method is investigated and compared with the centralized integration processing method. Results show that new method has analogous position and velocity accuracy with better computation efficiency.

In order to use a stand-alone global navigation satellite system (GNSS) receiver to determine the stable instantaneous velocity, a new hybrid GNSS velocimetry approach combining carrier phase and Doppler measurements is proposed. This is a data fusion problem. The problem is expressed as a state-space model, in which the deviation between the average velocity determined by the time difference carrier phase approach and the instantaneous velocity is represented by the uncertainty of the state model. In kinematic applications, this uncertainty is often variant and hard to be known in advance, a predefined process noise level of the state model is often not sufficiently accurate in the whole working time. Here, an adaptive Kalman filtering approach is employed to fix this problem. To verify the proposed approach, one static experiment and two dynamic experiments with different sampling intervals are performed, separately. All results demonstrate the validity and stability of the proposed approach.

Mechanical–structural vibration and/or rotational parts of the targets will induce micro-Doppler frequency in addition to the main Doppler components. In the today's military era, detections, measurements and decision making have to be made after the thorough analysis of main and micro-Doppler signatures of the targets to get their full profile particularly for defence applications. In addition, few of the low radar cross-section targets can be detected only by extracting and processing the micro-Doppler signatures corresponding to the rotations of their propellant rotor blades. Therefore, experimental studies to measure the micro-to-macro rotation/motion generated Doppler frequency and performing its associated measurements become significant. The authors built a C-band (5.3 GHz) continuous wave radar and used it to measure the Doppler frequency generated by micro-to-macro rotations/motions. The detection and measurement accuracy of the developed radar is assessed by series of different open-environment experimental case studies: revolution per minute measurement of rotating blades, separation of multiple rotating blades, oscillation per minute measurement of a swinging pendulum, detection of approaching/receding motion and the Doppler signature extraction of walking/jogging/cycling person. All these measurement values are validated against the standard master instrument readings and theoretical calculations. Finally, the limitations of this system and required near-future research works to enhance its performance are listed.

Rotor blades of large, modern wind turbines are susceptible to lightning strikes. In order to produce a design that resists lightning strikes, it is crucial to simulate lightning current propagation in the blade components. Since the current in the blade is generated by the superposition of potential and induced electric fields, a coupling exists between electric and magnetic fields which need to be calculated by an imposed integral constraint at each time step. Commercial software packages can deal with such constraints, but it results in time-consuming computations. Therefore, this work aims to develop a numerical methodology able to compute the voltage which drives the lightning current through the structure. In this way, the problem is reformulated as a voltage-driven one which in turn allows a simple subsequent coupling of electrical and magnetic problems. The computation of the voltage waveform was accomplished using the fast Fourier transform and the finite element method (FEM) to compute the structure impedance in the frequency domain. The developed procedure showed high efficiency for a blade subjected to different lightning impulses. It allows a description of the time-dependent lightning current to be given, as well as the distribution of current within the blade conductors.

This study proposes an alternative method to calculate the transient responses of multi-conductor overhead transmission lines based on ABCD representation, recursive convolutions and numerical method for rational approximation in the frequency-dependent curves. In the classical universal line model, the characteristic admittance matrix and propagation matrix are represented by rational functions. In , previous and correct identification of the modal travelling times is required. However, these modal travelling times are estimated numerically, which do not offer good accuracy in some cases. This fact has a considerable effect on the rational representation of itself and consequently on the transient responses. In the alternative method, a previous estimation of the modal travel times is unnecessary because when using the ABCD representation for each propagation mode, a direct relation exists between the currents and tensions of the receiving and sending ends. These relationships are fitted by smooth rational functions, and then, using recursive convolution methods, the authors obtain the explicit equations of the currents and voltages to calculate the transient responses. The results demonstrate that the alternative method is accurate when compared with the frequency-domain solution of the transmission line transformed to the time domain using the numeric Laplace transform and with the Bergeron method.

In this study, a multidisciplinary design procedure for sandwich radomes is presented. This methodology is composed of two parallel paths which are related to each other, one for electromagnetic behaviour and the other for its mechanical properties. The electromagnetic performance and mechanical properties are often mutually related resulting in a parameter selection compromise between them. The presented methodology is applied on an A type sandwich panel for C-band weather applications. It is composed of primary electromagnetic and mechanical designs, dielectric constant measurement, and electromagnetic and mechanical optimisations. Mechanical design of the sample panels according to survival wind loading of 220 km/h is done numerically and experimentally. Pressure distribution on the radome structure caused by the wind load is calculated numerically. The critical buckling load (120 N) is reported according to ASTM C364 edge wised compression standard test. A sample A-type sandwich panel with the respective thicknesses of 13.2 and 0.6 mm for its core and face sheets, respectively, is fabricated and tested. The dielectric constants of each are measured by using two methods and the results, which are in agreement in both methods, are ∼1.05 and 3.3, respectively. The insertion loss of the fabricated panel is lower than 0.2 dB over the entire desired band.

In this contribution, a novel technique for discrimination of myopathy, amyotrophic lateral sclerosis (ALS) and healthy electromyograms is proposed using multifractal detrended fluctuation analysis (DFA). Electromyograms are aperiodic and non-stationary electrical signals which represent the complex dynamics of skeletal muscle tissues and nerve cells activities within the human body. In this study, non-linear and dynamic fluctuations of noisy and chaotic electromyograms are analysed using fractal geometry. Electromyography (EMG) signals of myopathy, ALS and healthy disorders were collected from an online existing database and the non-linear dynamics were initially characterised using multifractal DFA. Following this, five novel feature parameters were extracted from the multifractal spectrum of respective EMG signals. Analysis of variance test was conducted on the selected features to examine their statistical significance. Finally, classification of myopathy, ALS and healthy electromyograms was done using support vector machine and k-nearest neighbour classifiers. In this study, four classification tasks are reported and it was observed that the performance of the proposed method is reasonably satisfactory in discriminating different categories of electromyograms. In addition, the proposed method is also found to deliver comparable and even better results in comparison with the existing methods, studied on the same data set.

In this research, the return path discontinuity (RPD), located under the power amplifier (PA) substrate, of X-band transceiver module (Base), mounted on a four-layer printed circuit board (PCB), is investigated to improve the signal integrity by reducing the difference in the reference potential. This study is performed by initially employing the wirebond method, through the assessment of both numbers and sizes of bondwires by advanced design system (ADS). Six bondwires of 25 µm are added, producing an improvement of 6.82 dB for the reflection coefficient and 1.19 dB for the isolation and insertion loss. For further improvement, spiral shape defected ground structure (DGS) is implemented in the inner ground layer (layer 2) without using bond wires. The DGS simulation results illustrate an improvement of 3 dB for S ₁₁ and 0.6 dB for S ₁₂. To improve the electromagnetic compatibility (EMC), the authors propose combination and integration of both wirebond and DGS methods, called wirebond–DGS method, which results in an improvement of 11.86 dB for S ₁₁, 1.34 dB for S ₁₂ and S ₂₁, and 12.03 dB for S ₂₂. Finally, the wirebond–DGS RF module was fabricated and the measurement results exhibit an improvement of 8.07 dB for S ₁₁ and 9.39 dB for S ₂₂ in comparison with the fabricated Base module. In addition, 0.53 dB improvement for both S ₁₂ and S ₂₁ is also achieved.

This study introduces a simple and novel partial discharge (PD) detection method for generator condition monitoring applications. The proposed method uses statistical operator ‘Variance’ which is proportional to the power of an electrical signal. It was validated by field measurement conducted at four in service hydro-generators: two having heavily aged windings and the other two having identical new. First, accuracy of detecting PD pulses was verified by comparing with wavelet-based method. The proposed method detected all the PD pulses with a ‘Precision’ higher than 90% and recall of 100%. As the second step phase resolved PD (PRPD) patterns generated using the proposed method were compared with commercial PD monitoring systems. It was found that the overall similarity was above 0.75. Finally, extracted PD pulses were used to calculate the polarity wise dissipated PD energies. The calculated energies were correlated with identified PD sources through series of off-line tests and visual inspections. It was observed that discharges due to loosen windings and corona activity were well correlated with estimated PD energies. All these validation processes indicated that the proposed method effectively and accurately detect PD pulses and can be used as a diagnostic tool for generator applications.

In this study, an improved cuckoo search (ICS) algorithm is presented to solve the parameter estimation problem of soil structure. For 1D soil parameters estimation, the objective function is constructed based on the relative root-mean-square error between measured and calculated soil apparent resistivity curves. The ICS algorithm extends the search range of soil model parameters through variable control parameters. Optimal resistivity and thickness of each layer are obtained by several different algorithms under the same test conditions based on two known four-layer soil models without noise. The results show that the ICS algorithm performs better in minimising error. This study also tests the optimisation performance of the ICS algorithm in two actual high-quality data cases, comparative results of the ICS algorithm and existing literature validate the effectiveness and accuracy of ICS. Moreover, in order to make soil estimation results more visible in a specific area, the combination of the proposed estimated algorithm and a new arrangement way of measurement lines is proposed to estimate 3D soil electric parameter structure in Chengdu, China.