rss_2.0Journal of Electrical Engineering FeedSciendo RSS Feed for Journal of Electrical Engineering of Electrical Engineering Feed classification with aggregating multiple spatial views using a machine-learning approach<abstract><title style='display:none'>Abstract</title> <p>The article proposes a solution for object classification using multiple views generated from 3D data rendering and convolutional neural networks. For presentation purposes and easier verification of the solution, an application was developed to create views of 3D objects, classify them using the selected CNN, and evaluate the performance of the CNN. The evaluation is based on metrics and characteristics described in the article. Seven testing objects were used to verify the proposed solution; five CNNs were tested for each.</p> </abstract>ARTICLEtrue enhancement of band-pass FIR filter-based M-class phasor estimation<abstract><title style='display:none'>Abstract</title> <p>The paper presents the performance enhancement of band-pass filter-based M-class phasor estimation. The performance of the M-class phasor estimation using a band-pass FIR filter is enhanced with a magnitude correction factor for the off-nominal frequency range. The band-pass filter is implemented for the phasor estimation with various window functions Tukey, Rife Vincent class-I order-2 (RV2), Hamming, Hanning, Blackman, and Flat-top (FT) and its performance are evaluated under the steady and dynamic state tests prescribed by the standard. A rigorous performance analysis of enhanced phasor estimation using band-pass FIR filter with various window functions is presented with the accuracy indices of total vector error (TVE), frequency error (FE), and rate of change of frequency error (RFE). The result analysis reveals that the performance enhanced phasor estimation using band-pass FIR filter offers significantly less error than reported work at the low sampling rate. The design and performance analysis of the phasor estimation using the band-pass FIR filter is performed in the MATLAB platform.</p> </abstract>ARTICLEtrue simple 90° hybrid branchline coupler with wideband phase balance for 5G applications<abstract><title style='display:none'>Abstract</title> <p>A 90° hybrid coupler operating at a central frequency of 5.40 GHz is introduced, offering high-performance characteristics with compact dimensions of 616.65 mm&amp;sup2; (33.3 mm × 18.5 mm). These features are achieved while maintaining a design that makes it easy to produce. The unique aspect of this microstrip FR4 substrate-based design is the consistent S-parameters, which remain steady despite changes in structural dimensions, thereby making it adaptable to fabrication variations. The reported S-parameters measured in 5.4 GHz are as follows: |S<sub>11</sub>|= –29.46 dB, |S<sub>21</sub>|= –4.11 dB, |S<sub>31</sub>|= –3.96 dB, and |S<sub>41</sub>|= –21.23 dB. This hybrid coupler operates over a bandwidth of 0.8 GHz (16%), demonstrating remarkable performance within this spectrum. In addition to its design, the coupler exhibits robust resilience against changes in substrate parameters and structural dimensions, ensuring reliability during the fabrication process. Following thorough simulation studies, a physical prototype of the coupler was constructed and subjected to laboratory measurements. The experimental results align closely with the simulation data, validating the accuracy and predictability of the design. In comparison with other studies and designs documented in the literature, this compact, high-performance 90° hybrid coupler exhibits clear advantages in terms of size, isolation, phase deviation, and structural complexity. Therefore, the benefits and applicability of this presented structure in the context of microwave circuits and systems are underscored. It’s noteworthy to mention that the central frequency of 5.4 GHz falls within the sub-6 GHz 5G band range.</p> </abstract>ARTICLEtrue test-bench for SiC power devices using LabVIEW<abstract><title style='display:none'>Abstract</title> <p>This paper is devoted to the improvement existing models of electronics devices, which are used in powers electronics as switching devices, and investigate a LabVIEW-based automatic test-bench for Silicon carbide (SiC) power devices. In recent years, power electronic devices are required to be capable handle with higher voltage, leads to development of new generation of power electronic devices, such as SiC devices. However, using a simulation platform, such as Spice, to diminish the complexity of power electronic design with these new devices is hindered by the lack of precise models. The proposed test-bench enables not only measuring static characteristics of SiC power devices, but also extracting key parameters required by simulations. These extracted parameters are then employed in the existing device model, and the simulation results which are based on the model with original parameters and models with extracted parameters are compared with measured results. The comparison clearly demonstrates that parameters obtained from the proposed test-bench significantly enhance the Spice model.</p> </abstract>ARTICLEtrue of power control in the mobile network on the radiation level<abstract><title style='display:none'>Abstract</title> <p>The paper evaluates how the control of transmitted power affects the intensity of radiation in a mobile network cell. Cell models without power control, with standard power control and a model with power control and channel reallocation are considered. The relative reduction of radiation is evaluated and several examples of calculations are presented. Remarks are given on the dependence of radiation reduction on the number of traffic channels, traffic intensity and signal attenuation coefficient. The assessment procedure and results are based on previously verified traffic process simulation models.</p> </abstract>ARTICLEtrue and reliability analysis for broadband current array sensing system applied to GIS<abstract><title style='display:none'>Abstract</title> <p>In order to further improve the defect detection capability of gas insulated switchgear and avoid equipment faults, broadband current array sensing system is designed to simultaneously monitor the system status such as partial discharge, relative dielectric loss, and power frequency overvoltage. The dynamic model of the system is analysed, and based on which, the system state equation is obtained meanwhile fault observer is designed, and the system stability criterion under <italic>H</italic><sub>∞</sub> condition is calculated. The reliability of the system under different packet loss rates is verified based on cloud models, and the principle of using appropriate electromagnetic compatibility to prevent packet loss rates below 50% is proposed.</p> </abstract>ARTICLEtrue reinforcement learning based computing offloading in unmanned aerial vehicles for disaster management<abstract><title style='display:none'>Abstract</title> <p>The emergence of Internet of Things enabled with mobile computing has the applications in the field of unmanned aerial vehicle (UAV) development. The development of mobile edge computational offloading in UAV is dependent on low latency applications such as disaster management, Forest fire control and remote operations. The task completion efficiency is improved by means of using edge intelligence algorithm and the optimal offloading policy is constructed on the application of deep reinforcement learning (DRL) in order to fulfill the target demand and to ease the transmission delay. The joint optimization curtails the weighted sum of average energy consumption and execution delay. This edge intelligence algorithm combined with DRL network exploits computing operation to increase the probability that at least one of the tracking and data transmission is usable. The proposed joint optimization significantly performs well in terms of execution delay, offloading cost and effective convergence over the prevailing methodologies proposed for UAV development. The proposed DRL enables the UAV to real-time decisions based on the disaster scenario and computing resources availability.</p> </abstract>ARTICLEtrue measurement of skin temperature using a wearable two-channel PPG optical sensor supplemented by thermometers<abstract><title style='display:none'>Abstract</title> <p>This paper describes realization, basic properties, testing, and experiments with a special prototype of a wearable two-channel photoplethysmography (PPG) sensor supplemented by contact thermometers that maps the skin temperature at the place where the optical part of the sensor touches a measured hand part (typically a wrist and fingers). Preliminary measurement confirms that proposed I2C thermometers have proper stability and precision, so can be successfully used in the developed PPG sensor. The performed main experiments show that the significant increase of temperature was always observed at the place of the worn PPG sensors during the whole measurement. This rise of temperature affects mainly the PPG signal range, thus it has also influence on the quality of the sensed PPG wave. The conclusion formulates the final recommendation about the necessity of at least 5-minute time delay between the PPG sensor placement on the hand and the start of the PPG signal acquisition. While the current measurements were realized in normal laboratory conditions, the whole wearable PPG sensor consists of non-ferromagnetic materials and all parts are fully shielded by aluminum boxes to enable measurement in a low magnetic field environment which, is our final long term research aim.</p> </abstract>ARTICLEtrue sensitivity index-based multi-objective testcase prioritization<abstract><title style='display:none'>Abstract</title> <p>Test case prioritization (TCP) is a regression technique that sequences test cases by assigning priority based on specific criteria defined by software testers. Various parameters, such as code coverage, statement coverage, and method coverage, are utilized in Test Case Prioritization (TCP), wherein metaheuristic techniques are widely employed to determine the optimal order of test cases based on these specified parameters. However, simply applying these techniques does not ensure the satisfaction of all the needs of software testers. This paper introduces an empirical study that employs the multi-objective test case prioritization (MOTCP) technique to prioritize the test cases based on target points defined by software testers. The study calculates a Software Complexity Index (SCI) at the code level, identifying fault-prone areas. Furthermore, a Test-case Complexity Index (TCI) is also used for prioritization. The proposed technique incorporates various target points defined by the software tester to calculate SCI and TCI, which serve as our main objectives for TCP. A detailed analysis is also performed to examine the impact of these target points on the generated optimal order of test cases. Finally, the proposed model is compared with other state-of-the-art techniques across various evaluation parameters.</p> </abstract>ARTICLEtrue Ku band low-voltage and low-power CMOS low-noise amplifier with bulk isolation techniques<abstract><title style='display:none'>Abstract</title> <p>In this paper, a broadband(12-18G) low-noise amplifier (LNA) using 65-nm CMOS technology for satellite communication is presented. This LNA was designed in a cascode common source with inductive degeneration topology. In addition, the bulk isolation technique is employed to make the proposed LNA have a higher gain. Furthermore, a two-stage cascaded configuration combined with inductive parallel peaking technology is utilized to make the LNA achieve a wide operating band. For validation, we design this LNA in a 65nm CMOS technology. The simulated results show that S21 of 17.7dB <italic>± </italic>0.5dB, the input/output return loss of -10dB to -33dB and -12dB to -23dB, respectively. It offers the minimum noise figure (NF) performance of 3.33dB, reverse isolation(S12) better than 60dB, and third-order input point (IIP3) of -22.8 dBm obtained over the band of interest. Excluding the output buffer stage, the LNA is consuming 5.1 mW at a supply voltage of 0.8V and its layout area occupies 0.205 mm<sup>2</sup>.</p> </abstract>ARTICLEtrue block code with locality and availability inspired by tetrahedron<abstract> <title style='display:none'>Abstract</title> <p>The primary application of codes with locality and availability in distributed storage is for data recovery in case that data are lost on some damaged servers. Locality enables the recovery of lost data by contacting only a restricted number of remaining servers. Availability means that more than one subset of servers providing locality is available for data recovery for each server. The secondary application of these codes in distributed storage is to allow access to hot data in times of high demand. In this paper it is shown that the binary linear [14, 4, 7] code has locality 2 and availability 6 and it can be interpreted as a three-dimensional graph obtained from a [7, 3, 4] Simplex code. It is achieving upper bounds on basic parameters for codes with all-symbols locality and availability. This code can be a building element of more complex codes with scalability inspired by three-dimensional structures. The availability spectrum is introduced as a tool for analyzing codes with locality and availability.</p> </abstract>ARTICLEtrue activity recognition with fine-tuned CNN-LSTM<abstract> <title style='display:none'>Abstract</title> <p>Human activity recognition (HAR) by deep learning is a challenging and interesting topic. Although there are robust models, there is also a bunch of parameters and variables, which affect the performance such as the number of layers, pooling type. This study presents a new deep learning architecture that is obtained by fine-tuning of the conventional CNN-LSTM model, namely, CNN (+3)-LSTM. Three changes are made to the conventional model to increase the accuracy. Firstly, kernel size is set to 1×1 to extract more information. Secondly, three convolutional layers are added to the model. Lastly, average pooling is used instead of max-pooling. Performance analysis of the proposed model is conducted on the KTH dataset and implemented on Keras. In addition to the overall accuracy of the proposed model, the contribution of each change is observed individually. Results show that adding layers made the highest contribution followed by kernel size and pooling, respectively. The proposed model is compared with state-of-art and outperformed some of the recent studies with a 94.1% recognition rate.</p> </abstract>ARTICLEtrue of a bidirectional EV charger using unit template-based current-controlled synchronous reference frame hysteresis<abstract> <title style='display:none'>Abstract</title> <p>Existing distribution networks were not designed with large-scale electric vehicle (EV) charging infrastructure in mind. Integrating EV charging stations with the distribution grid might lead to power quality (PQ) issues at the point of common coupling (PCC). This work proposes a two-mode, unit template-based synchronous reference frame hysteresis current-controlled (SRF-HCC) three-phase Level 2 EV charger. Mode one focuses on charging the EV battery from the grid (G2V) and utilizes current and voltage control techniques to enhance battery life and performance. Whereas mode two enables the EV’s stored energy to be discharged to the grid (V2G) by the EV user, allowing the sale of power to support the transient effect of the grid voltage and frequency and enhancing the grid’s PQ. The HCC generates switching pulses for both the AC-DC and buck-boost converters. The SRF-based unit template-based control (SRF-UTC) method ensures system stability, voltage, and frequency regulation for power exchange with the grid by combining its efficiency with that of the HCC. The EV charger proposal comprises three primary components: a 3-phase bidirectional AC-DC converter, a bidirectional buck-boost converter, and a filter circuit. The proposed system was modeled using MATLAB/Simulink and evaluated in two case studies to assess its performance.</p> </abstract>ARTICLEtrue of tungsten tips for subsequent use as cold field emitters or STM probes<abstract> <title style='display:none'>Abstract</title> <p>This study investigates the crucial process of cleaning cold field emission electron emitters and scanning tunnel microscopy (STM) probes, particularly focusing on tungsten tips. The cleanliness of these tips is essential for maintaining optimal cathode properties, preventing impurities that can significantly affect the emission process. Various cleaning methods, including macroetching, ammonia cleaning, and hydrofluoric acid (HF) cleaning were explored and compared by scanning electron microscopy. The macroetching method, involving a mixture of hydrochloric acid, nitric acid, and hydrogen fluoride, proved to be too reactive, causing significant material removal and altering the tip’s structure. Ammonia cleaning did not significantly improve or harm the samples. However, oxide islands appeared in some areas, suggesting the potential formation of ammonium tungsten oxide. HF cleaning, specifically at 20% and 50% concentrations, demonstrated effectiveness in removing tungsten oxides without damaging the tip. Pre-cleaning with water and ethanol proved beneficial for subsequent HF refinement. Results suggest that HF is the most suitable method for oxide removal but a rinse with water is essential for removing residual sodium hydroxide. To maintain optimal properties, it is crucial to apply a less reactive layer quickly or transfer the tips to a water/ethanol bath to prevent oxidation.</p> </abstract>ARTICLEtrue test performance for a comparative evaluation of a voltage source inverter: Dual voltage source inverter<abstract> <title style='display:none'>Abstract</title> <p>This article proposes an adaptive Kernel-Hebbian least mean square (KHLMS) controller for a dual voltage source inverter (VSI). The recommended topology consists of a distributed energy resource (DER) supported VSI called main VSI (MVSI) and split capacitor supported VSI termed as auxiliary VSI (AVSI). Both the MVSI and AVSI are used to serve the shunt compensation when DER is not integrated with MVSI. The DER scenario is considered to suppress the active power flow shortage in the utility grid. Here, optimal active power flow control (OAPFC) is managed by MVSI and shunt compensation is achieved by AVSI during DER operated mode. Hence, a dual VSI based distribution static compensator (DSTATCOM) facilitates the configuration merits such as reduction in system downtime cost, filter rating switching stress etc. Supremacy of both the neural network (NN) based controller and topology is presented by comparing VSI (called AVSI) in the context of harmonic reduction in source side, voltage balancing, power factor (PF) enhancement, better voltage regulation and OAPFC. The experimental results are obtained through field programmable gate array (FPGA) based hardware units which exhibit radical improvement in the power quality (PQ) conferring as per the international standard grid code (IEEE-519-2017).</p> </abstract>ARTICLEtrue of laser induced periodic surface structures for gas sensing thin films and gas sensing verification of a NiO based sensor structure<abstract> <title style='display:none'>Abstract</title> <p>This study presents different approaches to increase the sensing area of NiO based semiconducting metal oxide gas sensors. Micro- and nanopatterned laser induced periodic surface structures (LIPSS) are generated on silicon and Si/SiO<sub>2</sub> substrates. The surface morphologies of the fabricated samples are examined by FE SEM. We select the silicon samples with an intermediate Si<sub>3</sub>N<sub>4</sub> layer due to its superior isolation quality over the thermal oxide for evaluating the hydrogen and acetone sensitivity of a NiO based test sensor.</p> </abstract>ARTICLEtrue and implementation of a current-fed dual active bridge converter for an AC battery<abstract> <title style='display:none'>Abstract</title> <p>Home battery has become more and more popular in which the AC battery is a trending product along with the AC-coupled system. The energy conversion of an AC battery commonly consists of a two-stage power converter to flexibly connect to the wide-range input battery voltage and different grid or load types. This study specifically concentrates on the DC/DC stage which plays an important role in transferring power with the battery. In addressing the need for isolation, bidirectional power flow, and limited battery current ripple, the Current-fed Dual Active Bridge (CFDAB) structure is chosen for this stage. This paper presents a comprehensive design for the CFDAB converter for an AC battery application, especially a technical solution focusing on zero voltage switching is applied to increase the efficiency of the converter. Finally, an experimental prototype is carried out to validate the performance of the CFDAB converter in both two modes of the power flow.</p> </abstract>ARTICLEtrue XPM effects in non-linear directional couplers for 4-bit gray code conversion and even parity verification<abstract> <title style='display:none'>Abstract</title> <p>The all-optical switching phenomena in the non-linear directional coupler using cross-phase modulation (XPM) effect have been proposed. It is designed to generate an all-optical XOR functionality, considering the XOR logic gates as a basic module the design and analysis of an efficient all-optical 4-bit binary to gray code converter and 4-bit even parity checker circuit is proposed. The design methodology includes the switching of a weak continuous-wave (CW) signal, which is controlled by the combination of two controlled pump signals. In this paper, mathematical analysis of the coupled mode theory associated with optical directional couplers has been discussed. The switching characteristics of XPM effect based All-optical directional couplers have been examined for appropriate values of the controlled pump signals. Appropriate values of extinction ratio and corresponding controlled pump signal levels are investigated for an efficient generation of XOR logic gates. Further, the detailed analysis of layout generation and design aspects of All-optical 4-bit binary to gray code converter and 4-bit even parity checker circuits have been carried out. The proposed methodology is verified by the appropriate simulation results, which include the transmittivity, extinction ratio (Xratio) curve variation and dynamic time domain plot associated with proposed units.</p> </abstract>ARTICLEtrue emulation of a floating incremental/decremental inverse memristor for memristor bandwidth extension<abstract> <title style='display:none'>Abstract</title> <p>The article explores the compact emulation of the inverse memristor through a circuit-based approach. It introduces a floating emulator architecture that incorporates a dual output OTA (Operation Transconductance Amplifier) and DVCC (Differential Voltage Current Conveyor), along with two grounded passive elements, to achieve the emulation of an inverse memristor. The utilization of grounded resistance allows for tunability over the realized behaviour. A key contribution of this research is the novel application of the inverse memristor to extend the operating frequency range of any memristor emulator circuit. Validation of the proposed emulator circuit, in both incremental and decremental modes, along with its application, is conducted using PSPICE-generated simulation results in the 0.18 µm TSMC CMOS technology. Additionally, an inverse memristor emulator configuration employing the IC LM13700 is presented, and its functionality is tested through a breadboard implementation.</p> </abstract>ARTICLEtrue simple design of low-loss quad-band Wilkinson power dividers<abstract> <title style='display:none'>Abstract</title> <p>In this paper, a novel design method for quad-band Wilkinson power dividers is proposed. The design method is based on using a quad-band microstrip line. In comparison with other design methods, the proposed method has the advantages of simplicity and low insertion loss. To validate the proposed method, an equal quad-band power divider operating at four bands of 0.7, 1.2, 1.78, and 2.28 GHz was simulated and measured. Good agreement between measured results and simulated ones is obtained. The measured results show that the developed quad-band power divider features low insertion loss of less than 0.75 dB, isolation greater than 20.92 dB, and return loss better than 18 dB at four operating bands.</p> </abstract>ARTICLEtrue