Majlesi Journal of Electrical Engineering
Volume:16 Issue: 1, Mar 2022

In this paper, the Electromagnetic Band-Gap (EBG) structures have been used to decrease the mutual coupling between two wideband quad-ridge horn antennas. The EBG structure is a small sheet with a length of 6 cm and a width of 10.6 cm, and it was placed vertically between the horn antennas, providing us with a very compact system. Full-wave CST simulations have been carried out to simulate the whole structure. A two-layer EBG structure has provided a 17 dB isolation over the 20-40 GHz frequency range. Moreover, to verify the proposed structure, EBG layers have been fabricated and measured. The S parameter and far-field measurements of the horn antennas were conducted to investigate the isolation and radiation patterns of the antennas. The measurement results were perfectly comparable with the simulations. Moreover, because of the standalone characteristic of the designed EBGs, this structure can be used as an add-on unit to decrease the E-plane mutual coupling of any two antennas.

This paper presents Circuit Models which are developed for the analysis of the radiated and conducted susceptibilities of nonuniform shielded coaxial cables. In order to obtain the voltage and current distributions, a two-step procedure is performed. First, the cables are subdivided into several uniform sections. Second, the Branin’s mode is used to obtain the voltage and current distributions. This model can be used directly in the analysis of both time-domain and frequency-domain, and it has the ability to be used without the need of setting the preconditions for charges which are applied to its ends. In this paper, three examples of applications in the time and frequency domains are presented in order to validate our model. The first example focuses on a coaxial shielded cable to analyze both the conducted and radiated immunity, while the second example focuses on a nonuniform coaxial shielded cable. The third example presents a complex configuration of a coaxial cable which has been exposed to an electromagnetic field incident. Finally, the performed simulations and obtained results will be thoroughly described and analyzed.

The Electric transit buses (ETBs) are the main source for public transit to get the cleaner environment. The ETBs have gained popularity around the globe since the last decade. The ETBs are 14 % of the total transit buses around the world. The ETBs are heavy EVs and need more power to charge the high capacity batteries. The batteries used in these buses have the energy capacities between 80 kWh to 550 kWh. Such high capacity batteries take more to get charged. In order to increase the adoption of ETBs, a suitable number of high power dc charging infrastructures need to be installed in various main cities of the nations. The ETBs can operate with battery alone or fuel cell or combination of these two. Such ETBs are named as battery electric transit bus (BETB), fuel cell electric transit bus (FCETB) and hybrid electric transit bus (HETBs). As of 2020, out of total ETBs around the globe, 70 % are HETBs, 20 % are FCETBs and 10 % are BETBs. In this paper, the key parameters and comparison among these three batteries are shown. The major EV market holders are China, US, Europe and japan. The charging protocol used in the US and Europe is combined charging system. The charger capacity has reached up to 500 kW as of 2020. With such high power chargers it takes only less than half an hour to charge the high power batteries.

In a parallel transmission line, fault line, fault location, and classification have been identified separately. Since fault location takes more calculation time, it is unfit for protection purposes. Thus, this paper presented a new scheme that estimates the faulted line, fault location, and type of fault in a parallel transmission line, with the help of Phasor Measurement Units (PMU) and the Artificial Intelligence Technique. The proposed scheme uses phasors of Positive Sequence Voltage (PSV) and Positive Sequence Current (PSC) to detect the faulted line in a parallel transmission line. Further, the Artificial Neural Network (ANN) models have been designed to estimate the fault distance on a faulted line and classify the fault types. The PSV and PSC obtained from PMUs are selected as inputs because they have a negligible mutual coupling effect on the parallel transmission lines. The IEEE 9 bus system and the IEEE 30 bus system have been considered test cases to validate the proposed scheme. The proposed scheme is also validated by hardware in the loop on an OPAL-RT real-time simulator (OP RTS 5700). The results show that the proposed scheme identifies the fault line, fault distance, and type of fault regardless of its location on a parallel transmission line. Besides this, the proposed scheme has a quick response time, making it suitable for wide-area backup protection applications.

This paper focuses on introducing a transformerless DC/DC converter with low total switching device power in dual working modes including step-up and step-up/down modes. The proposed converter is analysed in terms of the continuous conduction mode, steady state, and efficiency with the replacement of parasitic resistance effects. The proposed converter in the step-up mode has a high voltage gain ratio and a continuous input current. Then, the other working mode of the proposed converter with relevant DC/DC converters is compared. By this comparison, the proposed converter has a high voltage gain ratio. Also, the converter characteristics such as voltage stress on power switches and charge pump capacitors are in a good condition in this mode. Finally, the experimental results from a laboratory made prototype and the obtained waveforms from the simulation in PLECS are presented for validation such as higher voltage gain ratio, lower total switching device power and better efficiency.

In this paper, a new hybrid low-power and area efficient Carry Look-Ahead Adder in CNFET technology based on the full-swing Gate Diffusion Input (GDI) technique is proposed. The proposed CLA design in GDI logic style, not only decreases the circuit area effectively but also decreases the power consumption and delay parameters as well. The proposed design is simulated in HSPICE using the CNFET model parameters. Finally, the simulation results justify a good improvement in the circuit performance parameters such as power consumption, delay, chip size area and power-delay product (PDP) for the proposed CLA circuit.

Plasma is a unique phase of matter constituting positively or negatively charged atoms, excited atoms, neutral atoms, electrons, radicals, etcetera displaying a unique role in the nuclear fusion research besides studying electrical discharges in the domain of switching devices and biomedical applications lately. We discuss in this extensive proposition the fundamental plasma characteristics such as Debye length, plasma oscillations, plasma sheath and condition for sustainability and confinement of plasmas, besides examining the elementary waves in plasmas namely zero waves, electron plasma wave and ion plasma wave. The inherent electron plasma wave and ion plasma wave is associated with the driving of plasma currents which in turn depends upon the density perturbation and thermal velocities of the electrons and ions. The application of external electromagnetic radiation such as laser (pump wave) into the plasma modifies the dispersion relations of electron and ion plasma wave, respectively. The laser stimulates a plethora of waves in the plasma and undergoes remarkable physical phenomena such as self-focusing and filamentation of laser beams. The excitation of sideband waves of the laser beams into the plasma plays a key role in imparting ponderomotive force on the electron plasma waves leading to turbulence in the plasmas due to coupling of the waves. The oscillatory velocity of the electron due to pump wave, plasma density perturbation, ponderomotive force and current densities are associated with the excitation of instabilities in the plasma. Conclusively, such waves and instabilities in unmagnetized and magnetized plasma is comprehensively studied and concluded by proposing the investigation of unexplored twisted electromagnetic wave-plasma interaction.

Soft tissue modeling is a challenging issue in tissue engineering. Tissue is a complex environment. It is assumed to represent viscoelastic behavior. Therefore, a complicated process is required to model its stress-strain relationship. In this paper, a non-integer order model is considered for the tissue’s mechanical behavior. The order indicates the amount that the tissue tends to behave as a pure viscous or pure elastic material. The main goal of the paper and the main contribution is to interpret the order as a function of the state of the material. To this aim, an experimental estimated model is used in which the order is considered as a function of time. Stress and strain signals are also available as functions of time. Then, an identification process is used to obtain the direct functionality of the order with respect to the state of the material (i.e. the momentary stress and strain). Data are gathered through an experimental setup. The stress signal calculated using a force sensor is highly noisy. Hence, de-noising is necessary. However, noise elimination may cause losing meaningful data. Also, a slight amount of noise enhances the generalization of the trained network in the identification process. Accordingly, a multi-level noise reduction method is used. The method is based on Empirical Mode Decomposition (EMD). To obtain the optimal noise reduction level, the noise reduction process is performed level by level and the best levels in train and test stages are chosen. Results show that supposing an explicit functionality between the order (as the amount of viscoelasticity) and the state of the tissue is reasonable. Also, it is verified that multi-level de-noising significantly improves the identification process.

A discrete-time (DT) high-resolution and low-power sturdy multi-stage noise-shaping (SMASH) sigma-delta (ΣΔ) modulator is introduced. It proposes major solution for high-resolution applications relying on M-bit digital input-feedforward (DFF) technique which eliminates a power-hungry analog adder before the stage’s quantizer, decreases number of comparators for quantizer implementation and reduces the swing of the integrator’s output and a 2nd-order noise-coupling (NC) technique realized by few extra analog paths and enhances the noise shaping of the modulator without adding active blocks. The effectiveness of the introduced modulator is supported by the behavioral simulation and extensive mathematical analyses. The proposed modulator along with conventional one is simulated in a 0.18μm CMOS technology. The results indicate an outstanding improvement in dynamic range (DR) and resolution with less complexity.