Journal of Applied Research in Electrical Engineering
Volume:2 Issue: 2, Summer and Autumn 2023

One type of electrical breakdown in solid insulation is electromechanical failure. In mineral processing, crushing rocks is energy intensive. Rock crushing using high voltage has many advantages, including high stone breaking efficiency, and is a new and efficient way to break stone. The shape of the electrode, the amount of applied voltage, and the selection of drilling process parameters are the main obstacles to using this method. In this study, based on the equivalent circuit of high voltage electro pulse failure, a mathematical model of high voltage electro pulse discharge in rock has been developed. Then, a high-voltage simulation model is developed based on the coaxial cylindrical electrode structure. This paper investigates the use of electromechanical failure phenomena for crushing minerals. High voltage pulses are used to crush the rock, then by simulating the relevant circuit, the necessary voltage for crushing three minerals is obtained and the feasibility of using this method is discussed. Finally, using the simulation and the obtained results, the possibility of using this method for crushing minerals has been investigated. This study provides a scientific basis for quantifying and predicting rock crushing using high-voltage technology in order to improve drilling efficiency and reduce energy loss.

The combined economic emission dispatch (CEED) is an important consideration in every power system. In this paper, a modified Mayfly Algorithm named Modified Individual Experience Mayfly Algorithm (MIE-MA) is used to solve the CEED optimization problem. The modified algorithm enhances the balance between exploration and exploitation by utilizing a chaotic decreasing gravity coefficient. Additionally, instead of the MA relying solely on the best position, it calculates the experience of a mayfly by averaging its positions. The CEED problem was modelled as a nonlinear optimization problem constrained with four equality and inequality constraints and tested on a grid-connected microgrid that consists of four dispatchable distributed generators and two renewable energy sources. The performance of the MIE-MA on the CEED problem was compared to Particle Swarm Optimisation (PSO), an MA variant that incorporates levy flight algorithm named IMA and Dragonfly Algorithm (DA) using the MATLAB R2021a software. The MIE-MA achieved the best optimum cost of 11306.6 $/MWh, compared to 12278.0 $, 12875.8$, and 17146.4$ of the DA, IMA and PSO respectively. The MIE-MA also achieved the best average optimum cost over 20 runs of 12163.48 $, compared to 12555.36 $, 13419.67 $ and 17270.08 $ of the DA, IMA, and PSO respectively. The hourly cost curve of the MIE-MA was also the best compared to the other algorithms. The MIE-MA algorithm thus achieves superior optimal values with fewer iterations.

Sudden cardiac death (SCD) leads to killing millions of people worldwide every year. In this article, sudden cardiac death is predicted by utilizing electrocardiogram signal processing. For this purpose, after extracting the signal of heart rate variations from the electrocardiogram signal, temporal and non-linear characteristics have been extracted. In the next step, by applying LDA to the combined feature vector, the feature dimensions are reduced and finally, healthy people and high-risk people are classified through Hybrid-RBF classifiers. The obtained results show that there are features in the signal of heart rate variations related to risk-taking individuals near the occurrence of sudden cardiac death, which completely distinguish them from healthy persons. It has also been shown that from 6 minutes before the occurrence of cardiac death, this increase in the probability of risk is quite evident, so that as we get closer to the occurrence of the accident, the probability of its occurrence also increases, and this is enough time to adopt strategies to prevent it. The simulation results achieved by the data available in the MIT-BIH database prove the ability of the presented methods in accurate diagnosis.

Path loss models estimate the average path loss a signal experiences at a particular distance from a transmitter. However, each type of existing path loss propagation model is designed to predict path loss in a particular environment that may be inaccurate in other different; hence selecting the best path loss model and optimizing it will minimize that inaccuracy. This work presents a comparative analysis of five empirical path loss models, COST- 231, ECC-33, Hata, SUI, and Ericsson model, with respect to the measured data from the 14 selected sites in Hawassa city, Ethiopia at 1800 MHz frequency bands. A drive test methodology was adopted for data collection and Nemo Handy and Nemo Outdoor were used as measuring tools for the test. Error measuring tools such as Root Mean Square Error, Mean Absolute Error, Standard Deviation, and Mean Absolute Percentage Error was used to select the terrain type of each site and the path loss model that best fits that site. The results showed not only Hawassa city consists of urban and Suburban terrains but also ECC-33 and Hata are better estimators for Hawassa Urban and Suburban areas with RMSE of 4.18 and 7.86 respectively. The model tuning using the Least Square Method reduced the RMSE of ECC-33 and Hata to 2.46 and 5.18 respectively. The reduction in RMSE shows that the tuned versions are close to the environment. Hence, using the tuned versions of the selected models will result in good cellular network design and enhance service quality.

Different types of optimal leader-follower consensus of high order multi-agent systems (MAS) under fixed, connected and directed communication topology are presented in this paper. The dynamics of each agent including the followers and their corresponding leader is a linear high order system. In first, Linear Quadratic Regulator (LQR) problem is discussed to achieve the optimal consensus for high order linear MAS with guaranteed the predefined both phase and gain margin. Then stochastic leader-follower consensus problem of MAS in presence of the Gaussian noise is designed. To tackle these problems, a set of fixed distributed control laws for each follower agent is designed, based on algebraic graph theory. Simulation results indicate the effectiveness of the proposed method and display the consensus in both cases via distributed control laws.

This article presents a tunable fourth-order band-pass filter that is designed using an operational trans-conductance amplifier (OTA), which can be used as an anti-aliasing filter (AAF) in the front-end of an analog-to-digital converter (ADC). It is necessary to use a suitable filter to prevent unwanted signals from entering the ADC. The bandwidth of the AAF should be designed according to the bandwidth of the ADC, therefore, matching these two bandwidths is one of the important challenges when using multi-bandwidth analog to digital converters in digital communication applications. The proposed band-pass filter is designed and simulated in 180nm CMOS technology. The simulation results show that by changing the two bias voltages of the proposed filter, its bandwidth can be changed according to the frequency range of ADSL, ADSL2, and ADSL2+ communication standards and it effectively attenuates unwanted signals.

For decades in the aerospace and control sciences, the Inertial Stabilized Platform (ISP) system has been studied to improve the accuracy of recipient photos or target tracking. This paper presents a nonlinear observer-based control method for three Degrees Of Freedom (3-DOF) ISP systems. First, a new formula of the state space equation for the 3-DOF ISP system is proposed to make this model suitable for designing an observer-based control. Then, by measuring the angular positions as output feedback, the angular velocities are estimated by the nonlinear observer, and Lyapunov-based nonlinear control techniques are used to design the observer. Furthermore, the exponential stability and convergence of the observer system are proved. Finally, the auxiliary control signal is considered so that the dynamics of the designed observer become a simple linear form and are easily controlled by the state feedback controller. Simulation results illustrate the effectiveness and feasibility of the proposed control strategy.

The optimal size and location of series capacitors is a critical challenge in a distribution network. In this paper, a novel approach for enhancing voltage stability in distribution networks through the optimal sizing and placement of series capacitors is proposed. The study introduces a technique to determine the optimal lines for connecting series capacitors based on line reactance and current. A modified Elephant Herding Optimization (MEHO) algorithm was used to determine the reactance sizes of the series capacitors and the best lines to place them for optimum system performance. To evaluate the effectiveness of the proposed method, three series capacitors are placed and sized in the standard IEEE 33-bus radial distribution system for stability enhancement. A comparison is conducted between the proposed MEHO algorithm-based approach, the original Elephant Herding Optimization (EHO) algorithm, and the IGWO-TS-based methods reported in the literature. The evaluation is performed by analyzing the system voltage profile, total system losses, and system voltage deviation index under varying loading conditions of 30%, 100%, and 120% of the system nominal loading. Results demonstrate that the proposed MEHO algorithm-based approach outperforms the other two methods significantly in all the scenarios, highlighting its effectiveness in voltage stability enhancement in distribution networks.

Modelling electric machines is crucial for analysing their behaviour and designing controllers. It is of the utmost importance to make use of a consistent equivalent circuit of the Doubly Fed Induction Machine (DFIM) that is applicable to a variety of operating modes. This is because it helps in the calculation of the machine's steady-state performance, converter ratings and controller set-points. Traditional models of doubly fed induction machines employ the steady-state equivalent circuit of a wound-rotor induction machine with all rotor parameters referred to the stator through a frequency conversion. The present study investigates the validity of the traditional steady-state circuit model by taking into account the sequence change in rotor voltages and currents at super-synchronous speeds. The validity of phasor diagrams constructed using the traditional circuit is assessed, with particular focus on super-synchronous operation in both motoring and generating modes. It has been demonstrated that the existing model is applicable to all rotor speeds (whether sub-synchronous or super-synchronous). However, caution should be exercised when utilising expressions of rotor reactive power that involve dynamic dq</em> and steady-state phasor models. Therefore, modified expressions are developed for rotor reactive power that are applicable regardless of the operating speed. The accuracy of the proposed method for different operating modes is confirmed by comprehensive simulation results developed with Matlab® Simulink. An investigation is also conducted into the sensitivity of rotor reactive power direction to parameter changes, and it is shown that machine parameter changes have a negligible effect on rotor reactive power direction.

This paper proposes a new relaying protocol for transmitting from a cellular user to the base station with the joint cooperation of a Full-Duplex (FD)-enabled Device-to-Device (D2D) pair. In the proposed scheme, the receiver of the D2D acts as a relay, with the cooperation of its transmitter pair via D2D communication between them. The cooperation approach of the D2D receiver is chosen as Adaptive Decode-and-Forward (ADF), while the cooperation strategy of the D2D transmitter is chosen as either ADF, Amplify-and-Forward (AF), or Hybrid relaying protocol. These scenarios are named "Decode and Joint Cooperation," "Amplify and Joint Cooperation," and "Hybrid and Adaptive Joint Cooperation," respectively. The Average Symbol Error Probability (ASEP) of the system is studied over independent and identically distributed (i.i.d) complex Gaussian (Rayleigh envelope) channels, with perfect Channel State Information (CSI) in the presence of Residual Self-Interference (RSI) at the FD relays, as well as Co-Channel Interference (CCI). Moreover, closed-form and high Signal-to-Interference-plus-Noise Ratio (SINR) tight ASEP approximations are established. The optimum power allocation is formulated based on the approximate relations, and the optimal solutions and their characteristics are discussed in detail. Analytical comparisons and simulations confirm the theoretical results and demonstrate significant performance improvements.

SAR images are used in many applications such as building detection. Extracting the building is very challenging due to the radar nature of the SAR images. However, due to the advantages of radar images such as day and night imaging, building extraction from SAR images is a hot topic. In this context, one of the main challenges is the effect of building orientation on the profile created in the SAR image. Also, the two geometric distortions of shadow and layover affect the SAR image. In most building extraction methods, shadow and double bounce are used as two main parameters in building detection. In this paper, different morphological profiles for detecting shadow index and double-bounce index (DMPSIDI) method have been developed using its combination with the method based on statistical features for building extraction. The DMPSIDI method is a morphological-based method that extracts buildings from SAR images independent of changing their profile. The proposed method is also robust to different data using weighting in the main parameters of shadow and double bounce.

This paper presents a comprehensive investigation of the electrical properties of a heterojunction tunnel field effect transistor with enhanced electrical tunneling current. The proposed device structure incorporates an extended source region and two parallel channels positioned above and below the source region. This configuration effectively amplifies the tunneling area, leading to a significant improvement in the on-state current. Moreover, the inclusion of an embedded oxide region between the source and drain regions confers the device with a high resistance to short channel effects. The combination of materials in both the source and channel region results in a staggered band alignment at the tunneling junction. This specific configuration leads to a lower threshold voltage for the initiation of tunneling. The impact of critical design parameters on the device performance has been thoroughly examined. A 2D variation matrix has been developed to compute the threshold voltage and on-state current variation based on the source doping density and gate workfunction, which serve as essential design parameters to optimize the electrical performance of the device. Furthermore, the device has achieved a unity current-ratio frequency of 300 GHz indicating its suitability for high-frequency applications. Additionally, the proposed structure provides an on-state current of 2.24×10-4 (A/µm), an off-state current of 1.24×10-15 (A/µm), an on/off current ratio of 1.81×1011, and a subthreshold swing of 5 (mV/dec). These characteristics make the device viable for energy-efficient, high-speed digital circuits.