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This paper introduces thermal‐stress analysis methods which follow electrical engineering procedures. The spring constant or c‐value is found to be related to the electrical impedance, combining dimensions and material characteristics in a performance parameter which simplifies calculations. Voltage is used to represent thermal deformation, and thermal forces are modelled as currents. Relationships equivalent to Ohm's Law are applied to calculate thermal stresses in leads or traces of surface‐mount assemblies. The thermal performance of laminates, e.g., thermal expansion coefficients of interconnect boards with a restraining core, and the thermal stresses in the bonded layers, are derived from the analysis of an electrical network which represents the composite structure. The method provides visual concepts which facilitate a first‐order solution of engineering problems related to thermal stress.

A two‐dimensional electromagnetic field model of a railway track and traction line is used to determine the equivalent track distributed transmission line parameters in the frequency range DC to 30kHz. The model is solved using the finite‐element method to find the minimum energy condition for two conditions: current excitation to obtain the resistance and inductance, and voltage excitation for the conductance and capacitance. The results have been confirmed using practical test data, and their application is illustrated in a time‐domain circuit simulation to model interference between power and signalling currents in a 750V DC electric railway.

Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high frequency for electrical devices is used to reduce the weight of the cables in the aircraft and spacecraft because of the skin effect. In the high-frequency system, a thinner cable cross-section is used, and a great weight reduction occurs in the aircraft. So, fuel economy, less and late wear of the materials (landing gear, etc.) can be obtained with decreasing weight. This paper aims to present the development of a functional multilevel inverter (FMLI) with fractional sinus pulse width modulation (FSPWM) and a reduced number of switches to provide high-frequency and quality electrical energy conversion.

After the production of FSPWM for FMLI with a reduced component, which, to the best of the authors’ knowledge, is presented for the first time in this study, is explained step by step, and eight operating states are given according to different FSPWMs operating the circuit. The designed inverter and modulation technique are compared by testing the conventional modular multilevel inverter on different loads.

According to application results, it is seen that there is a 50% reduction in cross-section from 100 Hz to 400 Hz with the skin effect. At 1000 Hz, there is a 90% cross-section reduction. The decrease can be in cable weights that may occur in aircraft from 10 kg to 100 kg according to different frequencies. It causes less harmonic distortion than conventional converters. This supports the safer operation of the system. Compared to the traditional system, the proposed system provides more amplitude in converting the source to alternating voltage and increases the efficiency.

FSPWM is developed for multilevel inverters with reduced components at the high frequency and cascaded switching studies in the power electronics of aircraft.

Although the proposed system has less current and power loss as mentioned in the previous sections, it contains fewer power elements than conventional inverters that are equivalent for different hardware levels. This not only reduces the cost of the system but also provides ease of maintenance. To reduce the cable load in aircraft and create more efficient working conditions, 400 Hz alternative voltage is used. The proposed system causes less losses and lower harmonic distortions than traditional systems. This will reduce possible malfunctions and contribute to aircraft reliability for passengers and cargo. As technology develops, it is revealed that the proposed inverter system will be more efficient than traditional inverters when devices operating at frequencies higher than 400 Hz are used. With the proposed inverter, safer operation will be ensured, while there will be less energy loss, less fuel consumption and less carbon emissions to the environment.

The proposed inverter structure shows that it can provide energy transmission for electrical devices in space and aircraft by using the skin effect. It also contains less power elements than the traditional inverters, which are equivalent for different levels of hardware.

The purpose of this paper is to suggest a polynomial complexity method for determining the range of the active and reactive power consumed in AC uncertain parameter circuits whose uncertain parameters are given as intervals.

First, the original problem is formulated as a corresponding interval quadratic range determination (IQRD) problem. Next, it is shown that the IQRD problem can be transformed equivalently into an interval linear range determination (ILRD) problem.

An efficient numerical method for solving the associated ILRD problem has been developed, capable of tackling the present active (or reactive) power range problem. It is based on the use of the outer solution y of an associated interval linear system defining the constraints in the ILRD problem.

The method yields the exact active and reactive power range if the number of the components y_i of y containing zero is relatively small (which is most often the case); otherwise, it provides tight outer bounds on the ranges sought.

The present method can be an alternative to the widely used Monte‐Carlo method since the former method provides exact (within rounding errors) results or tight outer approximations for lesser computation times.

To the best of the author's knowledge, the present paper suggests, for the first time, a simple interval analysis method of polynomial complexity for solving the problem considered which is inherently a NP‐hard problem (of exponential complexity).

With the growing scale of power grids, integrated power grids often contain multiple areas. When the control centre of each regional grid conducts an assessment of local voltage stability, the calculation is always based on the local regional power grid model. However, less consideration is given to a detailed model of the entire network, which may lead to a large calculation error. Under the premise of ensuring the data and information security of Supervisory Control and Data Acquisition between different regional power grid operation control centres, the purpose of this paper is to reduce calculation error simply by using the data of a local power network.

According to the calculation methodology of “decomposition and coordination” and the power balance equation of an interconnected power grid, an improved radial equivalent independent (REI) equivalent method, which can reflect the dynamic characteristics of interconnected power grids to a certain extent, is proposed in this paper. A mathematical model of multi-area-grid L indicator synergic computing is derived as well.

With the calculation of Institute of Electrical and Electronics Engineers (IEEE) standard grids and an actual grid model, it is proven that the method proposed in this paper can significantly improve the accuracy of the regional power grid L indicator calculation and achieve the synergic computing of a multi-area power system L indicator, without an increase in data interaction among the regional power grids.

The indicator of voltage stability among multi-area was obtained by using the improved REI equivalent method with the change of the load participation factor. Particularly, the coordinated calculation method can be implemented on a local power grid without knowledge of all the parameters of its interconnection, which can avoid possible leakage of confidential data and information of the system owners.

The purpose of the paper is to present a frequency-changing technique to realize a fast start-up radio frequency (RF) energy harvester.

First, a simple analysis of the input impedance of the rectifier circuit is presented, and based on the analysis, it is shown how the input impedance of the rectifier is changed during the rectifier charging. Then, the frequency-changing technique is presented in which the variation of the rectifier input reactance (capacitance) is partly compensated by changing the frequency of the transmitted RF signal. A harvester consisting of a four-stage rectifier and a simple series matching inductor, implemented based on Schottky diode, is employed to verify the technique.

With the input available power of −12 dBm, the simulated and the measured results prove that the proposed frequency-changing method compared to the typical fixed-frequency method shows more than 30 per cent decrease in the transient time to reach 0.5 V output voltage, while the final harvested output voltage is unchanged.

A frequency-changing technique is presented.

The purpose of this paper is to propose a fast, accurate and efficient algorithm for assessment of input impedance and consequently the evaluation of transient impedance of the grounding electrode.

The mathematical model is based on the thin wire antenna theory and related Pocklington integro-differential equation in the frequency domain, which is numerically treated via Galerkin-Bubnov variant of the indirect boundary element method (GB-IBEM). Two different approaches, scattered voltage method (ScVM) and induced electromotive force – boundary element method (IEMF-BEM), for input and transient impedance are discussed in detail. Extensive numerical experiments have been undertaken to analyze numerical sensitivity of the methods.

Although it was widely used so far, the ScVM, was shown to be unsuitable for the grounding impedance assessment because results are dependent on the number of elements used in the numerical solution. On the other hand, the other method, IEMF-BEM is rather stable, with the respect to the number of elements used and with excellent convergence rate. In addition, IEMF-BEM is much simpler to implement as it requires only multiplication of matrices already assembled within the procedure of current distribution calculation, as opposed to the ScVM which requires numerical integration of quasi-singular integrals which, by it self, can be very demanding.

The IEMF-BEM is originally developed by the authors and used for the first time for grounding impedance assessment. It is simple and very efficient and can easily be extended to arbitrary grounding configurations.

The once highly publicised Porcelain Enamelled Steel (PES) substrates seem to have disappeared from the public gaze, or have they? They certainly have not. If anything, they have consolidated their place in electronics applications and are growing in use at a remarkable pace in particular applications supplied by the major USA source, namely Ferro‐ECA.

This paper aims to achieve two main objectives. First, to introduce to the literature a new versatile active building block, namely, voltage differencing differential voltage current conveyor (VD-DVCC) for analog signal processing applications. Second, to design a novel electronically tunable mixed-mode universal filter. The designed filter provides low-pass, high-pass, band-pass, band-reject and all-pass responses in voltage-mode (VM), current-mode (CM), trans-impedance-mode (TIM) and trans-admittance-mode (TAM).

The proposed filter uses two VD-DVCCs, three resistors and two capacitors. All the capacitors used are grounded, which is advantageous from the monolithic integration point of view. The VD-DVCC is designed and validated in Cadence software using CMOS 0.18 µm process design kit from Silterra Malaysia at a supply voltage of ±1 V.

The proposed novel filter enjoys many attractive features including as follows: the ability to operate in all four modes, no requirement of capacitive matching, tunability of quality factor (Q) independent of pole frequency, availability of both inverting and non-inverting outputs for VM and TIM mode, high output impedance explicit current output for CM and TAM, no requirement for double/negative input signals (voltage/current) for response realization and low active and passive sensitivities. The filter is designed for a pole frequency of 5.305 MHz. The obtained results bear a close resemblance with the theoretical findings.

The proposed novel filter structure requires a minimum number of active and passive components and provides operation in all four operating modes. The filter will find application in structures of mixed-mode systems.

The paper aims to develop expressions for calculating the mutual impedance between isolated conductors buried in homogeneous earth. The conductors have finite length and arbitrary position.

The conductors are represented by the use of elementary electric dipoles. Well‐known existing expressions are employed for the electric field of these dipoles. The induced voltages are evaluated and the final expressions for the mutual impedance are derived. The resulting expressions involve infinite double integrals, evaluated by using adaptive quadratures that are, however, time consuming. Therefore, an alternative approach is followed involving Sommerfeld integrals (SI) for representing the electric field of a dipole and a recently devised method for computing the SI, in the spatial domain, by using calculation of discrete complex images.

Final expressions for parallel and perpendicular conductors were derived and numerical results for several values of frequency, conductors' length and horizontal distance between them, were produced. Comparison to results produced with the well‐known Pollaczek formula showed excellent agreement.

For future research, it is possible to use the developed expressions for earthing systems study, where the grounding grid is discretized and the moment method is invoked.

Currently, the formulas used for calculating mutual impedance are valid for parallel conductors of infinite length. With the present work, accurate expressions are given for finite length and arbitrary horizontal positioned conductors. In addition, the use of SI and the discrete complex image method results in a rapid and efficient tool for massive impedance calculations.