rss_2.0Journal of Electrical Engineering FeedSciendo RSS Feed for Journal of Electrical Engineering of Electrical Engineering Feed of a memcapacitance emulator utilizing a singular current-mode active block<abstract><title style='display:none'>Abstract</title> <p>This paper introduces a novel circuit design for a memcapacitance emulator, employing a single Voltage Differencing Current Conveyor (VDCC) as its core element. The emulator circuit has been intricately designed, employing only capacitors as grounded passive components. One remarkable aspect of these circuits is their inherent electronic tunability, allowing for precise control of the achieved inverse memcapacitance. The theoretical analysis of the emulator includes a comprehensive examination of potential non-idealities and parasitic influences. Careful selection of passive circuit elements has been made to minimize the impact of these undesirable effects. In contrast to extant designs cataloged in the existing literature, the presented circuitry manifests remarkable simplicity in its configuration. Furthermore, it exhibits a wide operational frequency range, extending up to 50MHz, and effectively clears the non-volatility criterion. To substantiate the efficacy of the devised circuits, comprehensive LTSpice simulations have been conducted, employing a 0.18 μm TSMC process parameter and a power supply of ±0.9 V. These simulations provide robust evidence of the emulator’s performance, reaffirming the feasibility and practicality of the proposed approach in the domain of memcapacitance emulation.</p> </abstract>ARTICLEtrue of wide-band high-linearity transimpedance amplifier using standard CMOS technology<abstract><title style='display:none'>Abstract</title> <p>In this paper, the design methodology of a high-linearity wide-band transimpedance amplifier (TIA) for cable television (CATV) application is addressed. A simple four-stage topology is proposed to maintain a well-balanced linearity over a wide operating band. The regulated cascode (RGC) input stage is used to match an input impedance of 75 Ω, followed by a gain stage with enhanced bandwidth. The high-linearity output stage is able to drive the 75 Ω load directly with high output swing under a high supply voltage. The prototype is implemented with a standard 0.11μm CMOS process while occupying the silicon area of 0.034 mm<sup>2</sup>. The measurement results for the prototype show a peak gain of 76.6 dBΩ over a 3-dB bandwidth of 1.1 GHz with a considerably small gain ripple and an <italic>OIP</italic><sub>3</sub> of 20.4 dBm. The whole test chip consumes 447 mW DC power and the measured average input-referred noise current spectral density is 7.9 pA Hz<sup>−1/2</sup> up to 1 GHz.</p> </abstract>ARTICLEtrue performance analysis for smart fluid dampers<abstract> <title style='display:none'>Abstract</title> <p>Over the years, the Italian Government has taken significant strides in promoting road safety awareness among the students in high schools to create an awareness of prevention and a consciousness of road safety in the student population. In this context, an agreement was signed between the DICEAM Department of the “Mediterranea” University of Reggio Calabria (Italy) and the “Euclide” Higher Education Institute Bova Marina (Italy) to combine road safety with research science in the Science, Technology, Engineering, and Mathematics (STEM) area. With the primary aim of “knowing in order to act”, the students focused on the multi-physics design of magnetorheological fluid dampers as high-performance devices (simple to design and requiring reduced maintenance) for vehicle suspensions, especially class B vehicles. By combining road safety considerations with multi-physics scientific disciplines, the project seeks to emphasize the importance of prevention and knowledge-based action. The study explores the use of magnetorheological fluid dampers, powered by electric current and magnetic induction distribution with thermal loads, to provide appropriate yield stress for developing damping action with repercussions on the quality of road safety. The paper delves into the basic principles of FEM (Finite Element Method) techniques for analyzing an MR damper from both magnetostatic (the main cause generating the damping effect) and thermal perspectives (thermal effects are strongly influenced by environmental conditions). The analysis of an asymmetrical device, where the damping action relies on an MR fluid strip, reveals the significant influence of magnetic and thermal stresses on the magnetization of individual particles and the overall viscosity of the MR fluid.</p> </abstract>ARTICLEtrue of computer modeling of electromagnetic field propagation in urban scenarios for Internet of Things<abstract><title style='display:none'>Abstract</title> <p>The paper investigates software solutions to simulate radio waves propagation in urban environment, specifically for the context of the Internet of Things (IoT). The purpose of the study is to provide a comprehensive guide for utilizing the Altair Feko software to obtain a detailed representation of the IoT network, its associated parameters and how they relate to the modeling of electromagnetic fields. It is beneficial to simulate the network during the design stage to obtain valuable data and make necessary adjustments. The key features of a Sigfox or other low power IoT network can be obtained by simulation, enabling an evaluation of the network design prior to its actual implementation. Given the growing demand for IoT devices and networks, researching the optimal design and performance of such networks is of great importance. This underscores the need for continuous exploration of effective methods to achieve efficient design and performance of IoT networks.</p> </abstract>ARTICLEtrue of a battery charging system fed by thermoelectric generator panels using MPPT techniques<abstract><title style='display:none'>Abstract</title> <p>Thermal energy is a renewable energy source to generate electrical energy that is not fully developed. One device that converts thermal energy into electrical power is a thermoelectric generator (TEG). TEGs are available as modules of various sizes and voltage levels. This paper is about the design of a battery charging system powered by a TEG panel. The TEG panel is implemented using 150 TEG modules interconnected in series and parallel. Its power is transferred to a battery using two stages of DC/DC converters. The 1<sup>st</sup> stage is a Lou converter that is used for maximum power point tracking (MPPT) by a referenced perturb and observe (referenced P&amp;O) algorithm. The 2<sup>nd</sup> stage is a bidirectional converter based on buck-boost modes of operation. The system is used to charge a 9 V 1.2 Ah battery. The proposed MPPT algorithm’s performance is compared with a traditional P&amp;O algorithm. The TEG panel provided 27.5 W at a Δ<italic>T</italic> of 30 <sup>0</sup>C. The designed system is simulated in MATLAB SIMULINK.</p> </abstract>ARTICLEtrue and power efficient divide-by-32/33 dual-modulus pre-scaler using split-path TSPC with AVLS for frequency divider<abstract><title style='display:none'>Abstract</title> <p>Pre-scalers are electronic circuits used in phase-locked loops to multiply frequencies. This is achieved by dividing the high-frequency signals generated from a voltage-controlled oscillator. The high-frequency operation of pre-scaler circuits leads to significantly higher power consumption. To address this, D flip-flops (D-FF) realized using true-single phase clocking (TSPC) logic. The work suggests incorporating the Adaptive Voltage Level Source (AVLS) circuit with the Dual Modulus Pre-Scaler (DMPS) circuit to reduce power consumption. In addition to the incorporation of the AVLS circuit, pass transistor logic (PTL) used in the feedback, further minimizes transistors and power. This paper proposes three different designs for divide-by-32/33 DMPS circuit. The proposed-1 design combines regular TSPC-based D-FF with PTL in the feedback and an AVLS circuit, resulting in an average power reduction of 36.5%. The proposed-2 design employs split-path TSPC-based D-FF with logic gates and an AVLS circuit, achieving a power reduction of 46.9%. The proposed-3 design employs split-path TSPC-based D-FF with PTL in the feedback and an AVLS circuit, achieving a significant power reduction of 47.8% compared to the existing DMPS circuit and transistor count by 9.1%. The proposed circuits are realized using a CMOS 180 nm technology node. Cadence Virtuoso and Spectre tools are used. The proposed divide-by-32/33 DMPS circuits also realized in the CMOS 45 nm technology node to verify the functionality in the lower technology node. A power reduction of 46.86% observed when compared to the reference circuit. The proposed designs are both power- and area-efficient, making them promising solutions for minimizing power consumption in pre-scaler circuits.</p> </abstract>ARTICLEtrue analysis of speech enhancement using spectral gating with U-Net<abstract><title style='display:none'>Abstract</title> <p>Many speech processing systems’ crucial frontends include speech enhancement. Single-channel speech enhancement experiences a number of technological challenges. Due to the advent of cloud-based technology and the use of deep learning systems in big data, deep neural networks in particular have recently been seen as a potent means for complex classification and regression. In this work, spectral gating noise filter is combined with deep neural network U-Net to enhance the performance of speech enhancement network. Further, for performance analysis three distinct objective functions namely, Mean Square Error, Huber Loss and Mean Absolute Error are considered as loss functions. In addition, comparison of three different optimizers Adam, Adagrad and Stochastic Gradient Descent is presented. Proposed system is tested and evaluated on LibriSpeech and NOIZEUS datasets and compared to other state-of-the-art systems. It demonstrates that, in comparison to other state-of-the-art models, the proposed network outperformed them with PESQ scores of 2.737420 for training and 2.67857 for testing, along with better generalization ability.</p> </abstract>ARTICLEtrue predictive current control of Syn-RM based on time delay estimation approach<abstract><title style='display:none'>Abstract</title> <p>This paper investigates an optimal model-free control design for a synchronous reluctance motor (Syn-RM) with unknown nonlinear dynamic functions, parameter variations, and disturbances. The idea is to combine a predictive control with a time-delay estimation technique (TDE) in order to successfully deal with the system’s uncertainties and make the Syn-RM control scheme easy to implement in real-time. This model-free control strategy comprises two cascade control loops namely outer and inner loops. The outer loop is designed for the mechanical part of Syn-RM to ensure the convergence of the speed dynamics by using a proportional-integral controller while the inner loop is developed to control the uncertain dynamics of currents via an optimal robust controller. In the proposed current loop, the predictive control is enhanced by the inclusion of ultra-local model theory where dynamic functions and disturbances are estimated by instantaneous input-output measurements of the Syn-RM using the TDE approach. Moreover, a particle swarm optimization (PSO) algorithm is also proposed to find the optimal design parameters to improve the dynamic performances of the closed-loop control system. Numerical validation tests of the proposed TDE-based model-free predictive current control (TDE-MFPCC) method are performed in the simulation environment of the Syn-RM system, and the results show the robustness and the effectiveness of the proposed TDE-MFPCC compared to the conventional model-based PCC.</p> </abstract>ARTICLEtrue design and analysis of QCA-based T-flipflop for nanocomputing<abstract><title style='display:none'>Abstract</title> <p>This work presents a new T-flipflop design based on quantum-dot cellular automata technology, with the standard two inputs (<italic>T</italic> and clock) and two outputs (<italic>Q</italic> and <italic>Q̄</italic>). It adheres to the typical QCA layout design approach, which consists of two majority voters and one inverter (to produce the complementary output, <italic>Q̄</italic>). It is a single-layered design with no crossover. A memory loop is used to retain previous values and aid the toggling operation of the T-flipflop. This design achieves improved functionality and reduced area requirement compared to existing designs. In addition, the study investigated energy loss and cost functions. In particular, the total energy loss is reduced by 10% and 22% compared to the best design when analyzed with the QCAPro and QCADesigner-E (QDE) tools, respectively. The area-delay and energy-delay cost functions outperform the best current design by 1.3 and 1.07 times, respectively. Overall, this work advances QCA-based flipflop (QTFF) designs and emphasizes the potential of QCA technology for creating effective QCA circuits.</p> </abstract>ARTICLEtrue of sinewave amplitude estimation in the presence of additive noise and quantization error<abstract><title style='display:none'>Abstract</title> <p>This research paper delves into a comprehensive investigation concerning the impact of additive noise and quantization error on the precision of amplitude, offset, and phase estimates of a sine wave fitted to a set of data points acquired by a waveform digitizer. Simulation results are used to validate the expressions presented.</p> </abstract>ARTICLEtrue dual-mode loop resonators for microwave triplexer applications<abstract><title style='display:none'>Abstract</title> <p>In this paper, we study meandered topologies of a dual-mode loop resonator for microwave multiplexer applications. Compact channel filter structures that characterize controllable transmission zeros locating simultaneously at the lower stopband or upper stopband are, for the first time, investigated for such a kind of resonators and based on this, a microstrip triplexer is proposed. The studied triplexer uses one of the filter structures to realize the middle channel, and the rest structure to realize the upper and lower channels. The center frequencies of the three channels are 1.8 GHz, 2.0 GHz and 2.2 GHz, and the 3-dB fractional bandwidths are 3.6%, 3.6% and 4.1%, respectively. The developed triplexer features high channel-isolations of over 40 dB as a result of the controllable transmission zeros of the channel filters. </p> </abstract>ARTICLEtrue performance optimization of NOMA-assisted cooperative relay system with realistic impairments<abstract><title style='display:none'>Abstract</title> <p>This work aims to investigate the outage and throughput performance of non-orthogonal multiple access assisted cooperative relay system (CRS-NOMA) considering the realistic impairments caused due to in-phase and quadrature-phase imbalance (IQI), channel estimation errors (CEE), and successive interference cancellation (SIC) errors. More specifically, we investigate a model in which two-phase downlink transmission is carried out in two different modes: (i) CRS-NOMA without direct links and (ii) CRS-NOMA with direct links (CRS-DLNOMA). In CRS-NOMA mode, the source broadcasts a composite NOMA signal to destination users with the assistance of a decode-and-forward (DF) relay. In contrast, in CRS-DLNOMA, direct and cooperative links are available for transmission. We derive the analytical expressions of outage probability and throughput for both the NOMA destinations to evaluate the system performance of both CRS-NOMA and CRS-DLNOMA modes of transmission. Furthermore, numerical simulations also study and validate the influence of IQI, CEE, and SIC errors on the outage and throughput performance. The simulation results verify that realistic impairments degrade the system performance, but the presence of direct link has a positive impact on outage and throughput. Additionally, we use the golden search method to optimize the power allocation factor (PAF) and transmission rate to maximize the throughput at the near user while ensuring the throughput constraint at the far user. </p> </abstract>ARTICLEtrue reduction of grid-connected multilevel inverters using modulation of variable frequency carriers<abstract><title style='display:none'>Abstract</title> <p>Multilevel three-phase inverters are increasingly popular due to their ability to generate high-quality output voltage with harmonic distortion lower than traditional inverters. They are used in various applications, including grid-connected renewable energy systems, motor drives, and power transmission systems, to improve efficiency and reduce costs. The control quality of grid-connected multilevel inverters depends on various factors such as the modulation technique, switching frequency, and control strategy. A good control system can achieve a balance between output current harmonics and switching losses, improving the efficiency and performance of the inverter. This paper suggests a technique for reducing current harmonics of grid-connected multilevel three-phase inverters using variable frequency carriers, without any corresponding increase of the number of switching commutations. The effectiveness of the suggested method has been confirmed through simulation results, which were compared to those obtained from the method of phase opposite disposition modulation using fixed frequency carriers. </p> </abstract>ARTICLEtrue HfO layer growth at atomic layer deposition<abstract><title style='display:none'>Abstract</title> <p>Thin HfO<sub>2</sub> films atomic layer deposited from hafnium alkyl amide and oxygen plasma were analysed using spectroscopic ellipsometry and X-ray reflectivity. Low refractive index of the material for samples with less than 30 nm thickness marks the index inhomogeneity at the first stage of growth. The transition from rising density to a more stable growth takes place at about 10 to 25 nm film thickness. HfO<sub>2</sub> films used for resistive switching experiments demonstrate either clockwise or counterclockwise behaviour depending on the film thickness. The reason for this may be the disruption of the conductive filament at different metal-insulator interfaces, which could be favoured by several mechanisms. </p> </abstract>ARTICLEtrue miniaturized quintuple-band frequency selective surface based on enclosed cross slots<abstract><title style='display:none'>Abstract</title> <p>This article presents a low-profile quintuple-band frequency selective surface (FSS) that is designed as a sub-reflector for applications including satellite systems (C band), EPR (electron paramagnetic resonance) spectrometers, motion and traffic light crossing detectors (X band), Direct Broadcast Satellite and broadcasting satellite service (Ku band), and shortrange applications (K band). The dimensions of the miniaturized unit cell 0.08λ<sub>0</sub>×0.08λ<sub>0</sub>×0.012λ<sub>0</sub>, where, λ<sub>0</sub> is the free-space wavelength corresponding to the lower cut-off frequency. There are five stop bands, and frequencies at which they resonate are 6.3, 7.06, 9.30, 11.2, 14.0, and 18.64 GHz. The fractional bandwidths (FBW) of these bands are 62.6, 7.5, 9.2, 11, and 11.69%, respectively. Additionally, as a result of the structure’s four-fold symmetry, it exhibits a good polarization-insensitive response as well as a stable response in both the TE and TM modes. Full-wave simulation is performed on the structure, after which an equivalent circuit model is constructed. </p> </abstract>ARTICLEtrue of RF energy harvester for 700 MHz<abstract><title style='display:none'>Abstract</title> <p>Radio frequency energy harvester is the conversion of ambient radio frequency electromagnetic waves into usable electrical energy, powering low-power devices without traditional power sources. In this paper, a novel RF energy harvester is proposed for 700 MHz frequency band. For the purpose of rectification, a Greinacher voltage rectifier cum multiplier is used in the circuit and Schottky Diode HSMS-2852 is used for implementing a rectifier. The LC impedance matching is implemented to improve the circuit performance of the harvester including conversion efficiency and output voltage. Simulation of the rectifier is done using the PathWave Advanced Design System (ADS) software. The rectifier shows the optimized performance at 5 kΩ load impedance. Simulation results show the highest efficiency of 33.1 % and an output voltage of 3.2 V with 8 dBm RF power at 700 MHz input frequency. </p> </abstract>ARTICLEtrue glaucoma from fundus images using ensemble learning<abstract><title style='display:none'>Abstract</title> <p>Glaucomatous changes of the optic nerve head could be detected from fundus images. Focusing on optic nerve head appearance, and its difference from healthy images, altogether with the availability of plenty of such images in public fundus image databases, these images are ideal sources for artificial intelligence methods applications. In this work, we used ensemble learning methods and compared them with various single CNN models (VGG-16, ResNet-50, and MobileNet). The models were trained on images from REFUGE public dataset. The average voting ensemble method outperformed all mentioned models with 0.98 accuracy. In the AUC metric, the average voting ensemble method outperformed VGG-16 and MobileNet models, which had significantly weaker performance when used alone. The best results were observed using the ResNet-50 model. These results confirmed the significant potential of ensemble learning in enhancing the overall predictive performance in glaucomatous changes detection, but the overall performance could be negatively affected when models with weaker prediction performance are included. </p> </abstract>ARTICLEtrue gate activation functions of Bi-LSTM-based SC-FDMA channel equalization<abstract><title style='display:none'>Abstract</title> <p>In recent years, artificial neural networks (ANNs) have grown a lot and helped solve numerous problems in wireless communication systems. We have evaluated the performance of the Bidirectional-Long-Short-Term-Memory (Bi-LSTM) recurrent neural networks (RNNs) for joint blind channel equalization and symbol detection using a variety of activation functions (Afs) for the gate units (sigmoid) of Bi-LSTMs without requiring any prior knowledge of channel state information (CSI). The performance of Bi-LSTM networks with different AFs found in the literature is compared. This comparison was carried out with the assistance of three different learning algorithms, namely Adam, rmsprop, and SGdm. The research findings clearly show that performance, as measured by equalization accuracy, can be improved. Furthermore, demonstrate that the sigmoid gate activation function (GAF), which is commonly used in Bi-LSTMs, does not significantly contribute to optimal network behavior. In contrast, there are a great many less well-known AFs that are capable of outperforming the ones that are most frequently utilized. </p> </abstract>ARTICLEtrue fractional-order derivative based adaptive FitzHugh-Nagumo neuron model<abstract><title style='display:none'>Abstract</title> <p>Various neuron models have been proposed and are extensively examined in the scientific literature. The FitzHugh-Nagumo neuron model is one of the most well-known and studied models. The FitzHugh-Nagumo model is not biologically consistent but operationally simple. A fractional-order derivative is described as a derivative with a non-integer order. Caputo, Grünwald-Letnikov, and Riemann-Liouville are some of the well-known fractional order derivatives. However, a simple fractional-order derivative called the conformable fractional-order derivative has been proposed in the literature and it is much simpler to use. In literature, there are already neuron models with fractional-order derivatives. In this study, a FitzHugh-Nagumo model circuit with a conformable fractional derivative capacitor and conformable fractional derivative inductor is proposed. The proposed circuit is modelled, and its simulation results are given. The simulation results reveal that the model circuit shows both slow and fast adaptation in firing frequency under sustained current stimulation. </p> </abstract>ARTICLEtrue of electrical system protection against the effects of a magnetic storm<abstract><title style='display:none'>Abstract</title> <p>In the introduction of the presented work, the physical nature of the collapse of electrical energy transmission systems due to the influence of a magnetic storm is recalled. A mechanism is described by which, due to the non-linearity of the magnetic circuit of the system’s power transformers, quasi-direct currents are induced into the high-voltage part of the system, which cause thermal overload of these transformers. The article then suggests one of the possible ways to prevent these accidents. On the single-phase and then on the three-phase model, it is shown how these currents can be compensated. Using laboratory models, the compensation process was simulated and verified by measurements. </p> </abstract>ARTICLEtrue