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Electronics, Volume 10, Issue 5 (March-1 2021) – 111 articles

Cover Story (view full-size image): The IEEE 802.1Q-2018 standard embeds in Ethernet bridges novel features that are very important for automated driving, such as the support for time-driven communications. However, cars move in a world where unpredictable events may occur and determine unforeseen situations. To properly react to such situations, the in-car communication system must support event-driven transmissions with very low and bounded delays. This work addresses the benefits of a novel traffic management scheme, called EDSched, for IEEE38802.1Q bridges and end nodes that provides explicit support for a new traffic class, the event-driven real-time class. The paper presents the EDSched approach and provides the performance evaluation. EDSched works at the MAC layer and builds upon the mechanisms defined in the IEEE 802.1Q-2018 standard. View this paper
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Open AccessArticle
Investigation on a 220 GHz Quasi-Optical Antenna for Wireless Power Transmission
Electronics 2021, 10(5), 634; https://doi.org/10.3390/electronics10050634 - 09 Mar 2021
Viewed by 381
Abstract
This paper investigates a 220 GHz quasi-optical antenna for millimeter-wave wireless power transmission. The quasi-optical antenna consists of an offset dual reflector, and fed by a Gaussian beam that is based on the output characteristics of a high-power millimeter-wave radiation source-gyrotron. The design [...] Read more.
This paper investigates a 220 GHz quasi-optical antenna for millimeter-wave wireless power transmission. The quasi-optical antenna consists of an offset dual reflector, and fed by a Gaussian beam that is based on the output characteristics of a high-power millimeter-wave radiation source-gyrotron. The design parameter is carried on by a numerical code based on geometric optics and vector diffraction theory. To realize long-distance wireless energy transmission, the divergence angle of the output beam must be reduced. Electromagnetic simulation results show that the divergence angle of the output beam of the 5.6 mm Gaussian feed source has been significantly reduced by the designed quasi-optical antenna. The far-field divergence angle of the quasi-optical antenna in the E plane and H plane is 1.0596° and 1.0639°, respectively. The Gaussian scalar purity in the farthest observation field (x = 1000 m) is 99.86%. Thus, the quasi-optical antenna can transmit a Gaussian beam over long-distance and could be used for millimeter-wave wireless power transmission. Full article
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Open AccessArticle
ProMECoS: A Process Model for Efficient Standard-Driven Distributed Co-Simulation
Electronics 2021, 10(5), 633; https://doi.org/10.3390/electronics10050633 - 09 Mar 2021
Viewed by 237
Abstract
Co-simulation techniques have evolved significantly over the last 10 years. System simulation and hardware-in-the-loop testing are used to develop innovative products in many industrial sectors. Despite the success of these simulation techniques, their efficient application requires a systematic approach. In practice the integration [...] Read more.
Co-simulation techniques have evolved significantly over the last 10 years. System simulation and hardware-in-the-loop testing are used to develop innovative products in many industrial sectors. Despite the success of these simulation techniques, their efficient application requires a systematic approach. In practice the integration and coupling of heterogeneous systems still require enormous efforts. At this point in time no unified process for integration and simulation of DCP-based co-simulation scenarios is available. In this article we present ProMECoS, a process model for efficient, standard-driven distributed co-simulation. It defines the necessary tasks required to prepare, instantiate and execute distributed co-simulations according to the DCP standard. Furthermore, it enables the exploitation of front-loading benefits, thus reducing the overall system development effort. ProMECoS is based on the IEEE 1730 standard for Distributed Simulation Engineering and Execution Process. It adopts the artefacts of the DCP specification, and defines additional process artefacts. The DCP specification and its associated default integration methodology were developed by a balanced consortium in context of the ITEA 3 project ACOSAR. The DCP is compatible to the well-adopted FMI standard. Therefore both standards can be used together for seamless development using models, software, and real components. ProMECoS provides the necessary guidance for efficient product development and testing. Full article
(This article belongs to the Special Issue Tools and Languages for Object-Oriented Modeling and Simulation)
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Open AccessArticle
Performance Analysis and Design Considerations of the Shallow Underwater Optical Wireless Communication System with Solar Noises Utilizing a Photon Tracing-Based Simulation Platform
Electronics 2021, 10(5), 632; https://doi.org/10.3390/electronics10050632 - 09 Mar 2021
Viewed by 300
Abstract
The performance of the underwater optical wireless communication (UOWC) system is highly affected by seawater´s inherent optical properties and the solar radiation from sunlight, especially for a shallow environment. The multipath effect and degradations in signal-to-noise ratio (SNR) due to absorption, scattering, and [...] Read more.
The performance of the underwater optical wireless communication (UOWC) system is highly affected by seawater´s inherent optical properties and the solar radiation from sunlight, especially for a shallow environment. The multipath effect and degradations in signal-to-noise ratio (SNR) due to absorption, scattering, and ambient noises can significantly limit the viable communication range, which poses key challenges to its large-scale commercial applications. To this end, this paper proposes a unified model for underwater channel characterization and system performance analysis in the presence of solar noises utilizing a photon tracing algorithm. Besides, we developed a generic simulation platform with configurable parameters and self-defined scenarios via MATLAB. Based on this platform, a comprehensive investigation of underwater channel impairments was conducted including temporal and spatial dispersion, illumination distribution pattern, and statistical attenuation with various oceanic types. The impact of ambient noise at different operation depths on the bit error rate (BER) performance of the shallow UOWC system was evaluated under typical specifications. Simulation results revealed that the multipath dispersion is tied closely to the multiple scattering phenomenon. The delay spread and ambient noise effect can be mitigated by considering a narrow field of view (FOV) and it also enables the system to exhibit optimal performance on combining with a wide aperture. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
The Characteristics of Aluminum-Gallium-Zinc-Oxide Ultraviolet Phototransistors by Co-Sputtering Method
Electronics 2021, 10(5), 631; https://doi.org/10.3390/electronics10050631 - 09 Mar 2021
Viewed by 406
Abstract
In this thesis, Aluminum-Gallium-Zinc oxide (AGZO) photo thin film transistors (PTFTs) fabricated by the co-sputtered method are investigated. The transmittance and absorption show that AGZO is highly transparent across the visible light region, and the bandgap of AGZO can be tuned by varying [...] Read more.
In this thesis, Aluminum-Gallium-Zinc oxide (AGZO) photo thin film transistors (PTFTs) fabricated by the co-sputtered method are investigated. The transmittance and absorption show that AGZO is highly transparent across the visible light region, and the bandgap of AGZO can be tuned by varying the co-sputtering power. The AGZO TFT demonstrates high performance with a threshold voltage (VT) of 0.96 V, on/off current ratio of 1.01 × 107, and subthreshold swing (SS) of 0.33 V/dec. Besides, AGZO has potential for solar-blind applications because of its wide bandgap. The AGZO PTFT of this research can achieve a rejection ratio of 4.31 × 104 with proper sputtering power and a rising and falling time of 35.5 s and 51.5 s. Full article
(This article belongs to the Special Issue Ultrasensitive Photodetectors and Applications)
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Open AccessArticle
Approximate Array Multipliers
Electronics 2021, 10(5), 630; https://doi.org/10.3390/electronics10050630 - 09 Mar 2021
Viewed by 322
Abstract
This article describes the design of approximate array multipliers by making vertical or horizontal cuts in an accurate array multiplier followed by different input and output assignments within the multiplier. We consider a digital image denoising application and show how different combinations of [...] Read more.
This article describes the design of approximate array multipliers by making vertical or horizontal cuts in an accurate array multiplier followed by different input and output assignments within the multiplier. We consider a digital image denoising application and show how different combinations of input and output assignments in an approximate array multiplier affect the quality of the denoised images. We consider the accurate array multiplier and several approximate array multipliers for synthesis. The multipliers were described in Verilog hardware description language and synthesized by Synopsys Design Compiler using a 32/28-nm complementary metal-oxide-semiconductor technology. The results show that compared to the accurate array multiplier, one of the proposed approximate array multipliers viz. PAAM01-V7 achieves a 28% reduction in critical path delay, 75.8% reduction in power, and 64.6% reduction in area while enabling the production of a denoised image that is comparable in quality to the image denoised using the accurate array multiplier. The standard design metrics such as critical path delay, total power dissipation, and area of the accurate and approximate multipliers are given, the error parameters of the approximate array multipliers are provided, and the original image, the noisy image, and the denoised images are also depicted for comparison. Full article
(This article belongs to the Special Issue Circuits and Systems for Approximate Computing)
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Open AccessFeature PaperReview
Blockchain Applications to Improve Operation and Security of Transportation Systems: A Survey
Electronics 2021, 10(5), 629; https://doi.org/10.3390/electronics10050629 - 09 Mar 2021
Viewed by 432
Abstract
Blockchain technology continues to grow and extend into more areas with great success, which highlights the importance of studying the fields that have been, and have yet to be, fundamentally changed by its entrance. In particular, blockchain technology has been shown to be [...] Read more.
Blockchain technology continues to grow and extend into more areas with great success, which highlights the importance of studying the fields that have been, and have yet to be, fundamentally changed by its entrance. In particular, blockchain technology has been shown to be increasingly relevant in the field of transportation systems. More studies continue to be conducted relating to both fields of study and their integration. It is anticipated that their existing relationships will be greatly improved in the near future, as more research is conducted and applications are better understood. Because blockchain technology is still relatively new as compared to older, more well-used methods, many of its future capabilities are still very much unknown. However, before they can be discovered, we need to fully understand past and current developments, as well as expert observations, in applying blockchain technology to the autonomous vehicle field. From an understanding and discussion of the current and potential future capabilities of blockchain technology, as provided through this survey, advancements can be made to create solutions to problems that are inherent in autonomous vehicle systems today. The focus of this paper is mainly on the potential applications of blockchain in the future of transportation systems to be integrated with connected and autonomous vehicles (CAVs) to provide a broad overview on the current related literature and research studies in this field. Full article
(This article belongs to the Special Issue Security of Cyber-Physical Systems)
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Open AccessCommunication
Next Generation Industrial IoT Digitalization for Traceability in Metal Manufacturing Industry: A Case Study of Industry 4.0
Electronics 2021, 10(5), 628; https://doi.org/10.3390/electronics10050628 - 09 Mar 2021
Viewed by 701
Abstract
This paper investigates digital traceability technologies taking careful consideration of the company’s needs to improve the traceability of products at the production of GPV Group as well as the efficiency and added value in their production cycles. GPV is primarily an electronics manufacturing [...] Read more.
This paper investigates digital traceability technologies taking careful consideration of the company’s needs to improve the traceability of products at the production of GPV Group as well as the efficiency and added value in their production cycles. GPV is primarily an electronics manufacturing service company (EMS) that manufactures electronic circuit boards, in addition to big metal products at their mechanics manufacturing sites. The company aims to embrace the next generation IoT technologies such as digital traceability in their internal supply chain at manufacturing sites in order to stay compatible with the Industry 4.0 requirements. In this paper, the capabilities of suitable digital traceability technologies are screened together with the actual GPV needs to determine if deployment of such technologies would benefit GPV shop floor operations and can solve the issues they face due to a lack of traceability. The traceability term refers to tracking the geolocation of products throughout the manufacturing steps and how that functionality can foster further optimization of the manufacturing processes. The paper focuses on comparing different IoT technologies and analyze their positive and negative attributes to identify a suitable technological solution for product traceability in the metal manufacturing industry. Finally, the paper proposes a suitable implementation road map for GPV, which can also be adopted from other metal manufacturing industries to deploy Industry 4.0 traceability at shop floor level. Full article
(This article belongs to the Special Issue Applications of Next-Generation IoT)
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Open AccessArticle
A Modified KNN Algorithm for High-Performance Computing on FPGA of Real-Time m-QAM Demodulators
Electronics 2021, 10(5), 627; https://doi.org/10.3390/electronics10050627 - 09 Mar 2021
Cited by 1 | Viewed by 457
Abstract
A methodology for scalable and concurrent real-time implementation of highly recurrent algorithms is presented and experimentally validated using the AWS-FPGA. This paper presents a parallel implementation of a KNN algorithm focused on the m-QAM demodulators using high-level synthesis for fast prototyping, parameterization, and [...] Read more.
A methodology for scalable and concurrent real-time implementation of highly recurrent algorithms is presented and experimentally validated using the AWS-FPGA. This paper presents a parallel implementation of a KNN algorithm focused on the m-QAM demodulators using high-level synthesis for fast prototyping, parameterization, and scalability of the design. The proposed design shows the successful implementation of the KNN algorithm for interchannel interference mitigation in a 3 × 16 Gbaud 16-QAM Nyquist WDM system. Additionally, we present a modified version of the KNN algorithm in which comparisons among data symbols are reduced by identifying the closest neighbor using the rule of the 8-connected clusters used for image processing. Real-time implementation of the modified KNN on a Xilinx Virtex UltraScale+ VU9P AWS-FPGA board was compared with the results obtained in previous work using the same data from the same experimental setup but offline DSP using Matlab. The results show that the difference is negligible below FEC limit. Additionally, the modified KNN shows a reduction of operations from 43 percent to 75 percent, depending on the symbol’s position in the constellation, achieving a reduction 47.25% reduction in total computational time for 100 K input symbols processed on 20 parallel cores compared to the KNN algorithm. Full article
(This article belongs to the Special Issue System-on-Chip (SoC) Design and Its Applications)
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Open AccessArticle
Novel BSSSO-Based Deep Convolutional Neural Network for Face Recognition with Multiple Disturbing Environments
Electronics 2021, 10(5), 626; https://doi.org/10.3390/electronics10050626 - 08 Mar 2021
Viewed by 400
Abstract
Face recognition technology is presenting exciting opportunities, but its performance gets degraded because of several factors, like pose variation, partial occlusion, expression, illumination, biased data, etc. This paper proposes a novel bird search-based shuffled shepherd optimization algorithm (BSSSO), a meta-heuristic technique motivated by [...] Read more.
Face recognition technology is presenting exciting opportunities, but its performance gets degraded because of several factors, like pose variation, partial occlusion, expression, illumination, biased data, etc. This paper proposes a novel bird search-based shuffled shepherd optimization algorithm (BSSSO), a meta-heuristic technique motivated by the intuition of animals and the social behavior of birds, for improving the performance of face recognition. The main intention behind the research is to establish an optimization-driven deep learning approach for recognizing face images with multiple disturbing environments. The developed model undergoes three main steps, namely, (a) Noise Removal, (b) Feature Extraction, and (c) Recognition. For the removal of noise, a type II fuzzy system and cuckoo search optimization algorithm (T2FCS) is used. The feature extraction is carried out using the CNN, and landmark enabled 3D morphable model (L3DMM) is utilized to efficiently fit a 3D face from a single uncontrolled image. The obtained features are subjected to Deep CNN for face recognition, wherein the training is performed using novel BSSSO. The experimental findings on standard datasets (LFW, UMB-DB, Extended Yale B database) prove the ability of the proposed model over the existing face recognition approaches. Full article
(This article belongs to the Special Issue Face Recognition Using Machine Learning)
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Open AccessArticle
Design and Implementation Procedure of a High-Gain Three-Input Step-Up 1 kW Converter
Electronics 2021, 10(5), 625; https://doi.org/10.3390/electronics10050625 - 08 Mar 2021
Cited by 1 | Viewed by 364
Abstract
The use of different sources to energize a load is convenient in many applications, particularly those where two or more renewable energy sources are employed, such as energy harvesting, hybrid vehicles, and off-grid systems. In these cases, a multi-input converter is able to [...] Read more.
The use of different sources to energize a load is convenient in many applications, particularly those where two or more renewable energy sources are employed, such as energy harvesting, hybrid vehicles, and off-grid systems. In these cases, a multi-input converter is able to admit sources with different characteristics and, if necessary, select the output power of each source. Several topologies of multi-input converters have been proposed to this aim; however, most of them are based on multistage designs, which decreases efficiency and increases control complexity, particularly when more than two sources are used. In this work, a three-input step-up converter, easy to control in open loop condition, is analyzed. A designed procedure is described, and experimental results are presented for a 1 kW power converter. The implemented converter results in a higher voltage gain and less storage element, keeping high efficiency compared to similar topologies. Using the procedure here proposed, this converter that was initially designed for photovoltaic applications is enabled to be used in medium- and high-power applications, for example, when renewable energy sources are used. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
Automatic Classification of Monosyllabic and Multisyllabic Birds Using PDHF
Electronics 2021, 10(5), 624; https://doi.org/10.3390/electronics10050624 - 08 Mar 2021
Viewed by 302
Abstract
Bioacoustics plays an important role in the conservation of bird species. Bio-acoustic surveys based on autonomous audio recording are both cost-effective and time-efficient. However, there are many bird species with different patterns of vocalization, and it is a challenging task to deal with [...] Read more.
Bioacoustics plays an important role in the conservation of bird species. Bio-acoustic surveys based on autonomous audio recording are both cost-effective and time-efficient. However, there are many bird species with different patterns of vocalization, and it is a challenging task to deal with them. Previous studies have revealed that many authors focus on the segmentation of bird audio without considering specific patterns of bird vocalization. Based on the existing literature, currently there is no work on the segmentation of monosyllabic and multisyllabic birds, separately. Therefore, this research addresses the aforementioned concern and also proposes a collection of audio features named ‘Perceptual, Descriptive, and Harmonic Features (PDHFs)’ that gives promising results in the classification of bird vocalization. Moreover, the classification results improved when monosyllabic and multisyllabic birds were classified separately. To analyze the performance of PDHFs, different classifiers were used in which Artificial neural network (ANN) outperformed other classifiers and demonstrated an accuracy of 98%. Full article
(This article belongs to the Special Issue Advances in Machine Learning)
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Open AccessArticle
A System-Level Exploration of Binary Neural Network Accelerators with Monolithic 3D Based Compute-in-Memory SRAM
Electronics 2021, 10(5), 623; https://doi.org/10.3390/electronics10050623 - 08 Mar 2021
Viewed by 336
Abstract
Binary neural networks (BNNs) are adequate for energy-constrained embedded systems thanks to binarized parameters. Several researchers have proposed the compute-in-memory (CiM) SRAMs for XNOR-and-accumulation computations (XACs) in BNNs by adding additional transistors to the conventional 6T SRAM, which reduce the latency and energy [...] Read more.
Binary neural networks (BNNs) are adequate for energy-constrained embedded systems thanks to binarized parameters. Several researchers have proposed the compute-in-memory (CiM) SRAMs for XNOR-and-accumulation computations (XACs) in BNNs by adding additional transistors to the conventional 6T SRAM, which reduce the latency and energy of the data movements. However, due to the additional transistors, the CiM SRAMs suffer from larger area and longer wires than the conventional 6T SRAMs. Meanwhile, monolithic 3D (M3D) integration enables fine-grained 3D integration, reducing the 2D wire length in small functional units. In this paper, we propose a BNN accelerator (BNN_Accel), composed of a 9T CiM SRAM (CiM_SRAM), input buffer, and global periphery logic, to execute the computations in the binarized convolution layers of BNNs. We also propose CiM_SRAM with the subarray-level M3D integration (as well as the transistor-level M3D integration), which reduces the wire latency and energy compared to the 2D planar CiM_SRAM. Across the binarized convolution layers, our simulation results show that BNN_Accel with the 4-layer CiM_SRAM reduces the average execution time and energy by 39.9% and 23.2%, respectively, compared to BNN_Accel with the 2D planar CiM_SRAM. Full article
(This article belongs to the Special Issue Computing-in-Memory Devices and Systems)
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Open AccessArticle
Design of a Memristor-Based Digital to Analog Converter (DAC)
Electronics 2021, 10(5), 622; https://doi.org/10.3390/electronics10050622 - 07 Mar 2021
Viewed by 464
Abstract
A memristor element has been highlighted in recent years and has been applied to several applications. In this work, a memristor-based digital to analog converter (DAC) was proposed due to the fact that a memristor has low area, low power, and a low [...] Read more.
A memristor element has been highlighted in recent years and has been applied to several applications. In this work, a memristor-based digital to analog converter (DAC) was proposed due to the fact that a memristor has low area, low power, and a low threshold voltage. The proposed memristor DAC depends on the basic DAC cell, consisting of two memristors connected in opposite directions. This basic DAC cell was used to build and simulate both a 4 bit and an 8 bit DAC. Moreover, a sneak path issue was illustrated and its solution was provided. The proposed design reduced the area by 40%. The 8 bit memristor DAC has been designed and used in a successive approximation register analog to digital converter (SAR-ADC) instead of in a capacitor DAC (which would require a large area and consume more switching power). The SAR-ADC with a memristor-based DAC achieves a signal to noise and distortion ratio (SNDR) of 49.3 dB and a spurious free dynamic range (SFDR) of 61 dB with a power supply of 1.2 V and a consumption of 21 µW. The figure of merit (FoM) of the proposed SAR-ADC is 87.9 fj/Conv.-step. The proposed designs were simulated with optimized parameters using a voltage threshold adaptive memristor (VTEAM) model. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Open AccessArticle
J-CO: A Platform-Independent Framework for Managing Geo-Referenced JSON Data Sets
Electronics 2021, 10(5), 621; https://doi.org/10.3390/electronics10050621 - 07 Mar 2021
Viewed by 368
Abstract
Internet technology and mobile technology have enabled producing and diffusing massive data sets concerning almost every aspect of day-by-day life. Remarkable examples are social media and apps for volunteered information production, as well as Open Data portals on which public administrations publish authoritative [...] Read more.
Internet technology and mobile technology have enabled producing and diffusing massive data sets concerning almost every aspect of day-by-day life. Remarkable examples are social media and apps for volunteered information production, as well as Open Data portals on which public administrations publish authoritative and (often) geo-referenced data sets. In this context, JSON has become the most popular standard for representing and exchanging possibly geo-referenced data sets over the Internet.Analysts, wishing to manage, integrate and cross-analyze such data sets, need a framework that allows them to access possibly remote storage systems for JSON data sets, to retrieve and query data sets by means of a unique query language (independent of the specific storage technology), by exploiting possibly-remote computational resources (such as cloud servers), comfortably working on their PC in their office, more or less unaware of real location of resources. In this paper, we present the current state of the J-CO Framework, a platform-independent and analyst-oriented software framework to manipulate and cross-analyze possibly geo-tagged JSON data sets. The paper presents the general approach behind the J-CO Framework, by illustrating the query language by means of a simple, yet non-trivial, example of geographical cross-analysis. The paper also presents the novel features introduced by the re-engineered version of the execution engine and the most recent components, i.e., the storage service for large single JSON documents and the user interface that allows analysts to comfortably share data sets and computational resources with other analysts possibly working in different places of the Earth globe. Finally, the paper reports the results of an experimental campaign, which show that the execution engine actually performs in a more than satisfactory way, proving that our framework can be actually used by analysts to process JSON data sets. Full article
(This article belongs to the Special Issue Novel Database Systems and Data Mining Algorithms in the Big Data Era)
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Open AccessArticle
Usage of Mathematical Modeling and Optimization in Development of Hydrogel Medical Dressings Production
Electronics 2021, 10(5), 620; https://doi.org/10.3390/electronics10050620 - 07 Mar 2021
Viewed by 354
Abstract
In connection with the significant complication of research objects of technological systems and the considerable increase in expenses for carrying out experimental research, improving the mathematical modeling methods of these systems is a current problem. By using the means of mathematical modeling and [...] Read more.
In connection with the significant complication of research objects of technological systems and the considerable increase in expenses for carrying out experimental research, improving the mathematical modeling methods of these systems is a current problem. By using the means of mathematical modeling and optimization, the calculation of the main technological parameters of the formation method of film hydrogel products based on silver-filled copolymers of 2-hydroxyethylmethacrylate with polyvinylpyrrolidone was performed. The technological parameters of the polymerization processes, chemical reduction of silver ions, and centrifugal formation of the film cloth were substantiated. These are the components of the technological process, which occurs in one stage in the form of a centrifugal unit. By using the obtained results, silver-filled films were obtained, which are characterized by unique properties and can be used in the treatment of trophic ulcers of lower limbs. Full article
(This article belongs to the Special Issue Electronization of Businesses - Systems Engineering and Analytics)
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Open AccessArticle
Analysis of a DC-DC Flyback Converter Variant for Thermoelectric Generators with Partial Energy Processing
Electronics 2021, 10(5), 619; https://doi.org/10.3390/electronics10050619 - 07 Mar 2021
Viewed by 521
Abstract
This paper presents a theoretical analysis of a DC-DC flyback converter variant applied in energy harvesting based on thermoelectric generators. The main contribution of the article is the analysis and obtaining the equations of the behavior of the converter with a rearrangement of [...] Read more.
This paper presents a theoretical analysis of a DC-DC flyback converter variant applied in energy harvesting based on thermoelectric generators. The main contribution of the article is the analysis and obtaining the equations of the behavior of the converter with a rearrangement of the elements of the traditional flyback converter in such a way that the converter only processes part of the energy while the other part is delivered directly to the load. This is achieved by connecting the secondary of the flyback in series with the load, and this assembly, in turn, is placed in parallel with the primary and the voltage source. This configuration means that the topology can only be a boost topology; however, there are benefits such as partial power processing (R2P2) and reduced stress on converter components in both voltage and current; all this leads to increase the efficiency. A Low Frequency Averaging Analysis (LFAA) was used to determine the behavior of the proposed circuit, and a simple equivalent circuit to analyze was obtained. In order to validate the theoretical analysis, a circuit was simulated in Spice and implemented in an 18 W prototype. Experimental results showed that the converter has an efficiency of 92.65%. Moreover, the rearranged flyback processed only 56% of the input power. Full article
(This article belongs to the Special Issue Innovative Technologies in Power Converters)
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Open AccessArticle
Evolutionary Optimization Strategy for Indoor Position Estimation Using Smartphones
Electronics 2021, 10(5), 618; https://doi.org/10.3390/electronics10050618 - 06 Mar 2021
Viewed by 468
Abstract
Due to their distinctive presence in everyday life and the variety of available built-in sensors, smartphones have become the focus of recent indoor localization research. Hence, this paper describes a novel smartphone-based sensor fusion algorithm. It combines the relative inertial measurement unit (IMU) [...] Read more.
Due to their distinctive presence in everyday life and the variety of available built-in sensors, smartphones have become the focus of recent indoor localization research. Hence, this paper describes a novel smartphone-based sensor fusion algorithm. It combines the relative inertial measurement unit (IMU) based movements of the pedestrian dead reckoning with the absolute fingerprinting-based position estimations of Wireless Local Area Network (WLAN), Bluetooth (Bluetooth Low Energy—BLE), and magnetic field anomalies as well as a building model in real time. Thus, a step-based position estimation without knowledge of any start position was achieved. For this, a grid-based particle filter and a Bayesian filter approach were combined. Furthermore, various optimization methods were compared to weigh the different information sources within the sensor fusion algorithm, thus achieving high position accuracy. Although a particle filter was used, no particles move due to a novel grid-based particle interpretation. Here, the particles’ probability values change with every new information source and every stepwise iteration via a probability-map-based approach. By adjusting the weights of the individual measurement methods compared to a knowledge-based reference, the mean and the maximum position error were reduced by 31%, the RMSE by 34%, and the 95-percentile positioning errors by 52%. Full article
(This article belongs to the Special Issue Indoor Positioning Techniques)
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Open AccessArticle
Unbalanced Two-Way Filtering Power Splitter for Wireless Communication Systems
Electronics 2021, 10(5), 617; https://doi.org/10.3390/electronics10050617 - 06 Mar 2021
Viewed by 499
Abstract
A compact unbalanced two-way filtering power splitter with an integrated Chebyshev filtering function is presented. The design is purely based on formulations, thereby eliminating the constant need for developing complex optimization algorithms and tuning, to deliver the desired amount of power at each [...] Read more.
A compact unbalanced two-way filtering power splitter with an integrated Chebyshev filtering function is presented. The design is purely based on formulations, thereby eliminating the constant need for developing complex optimization algorithms and tuning, to deliver the desired amount of power at each of the two output ports. To achieve miniaturization, a common square open-loop resonator (SOLR) is used to distribute energy between the two integrated channel filters. In addition to distributing energy, the common resonator also contributes one pole to each integrated channel filter, hence, reducing the number of individual resonating elements used in achieving the integrated filtering power splitter (FPS). To demonstrate the proposed design technique, a prototype FPS centered at 2.6 GHz with a 3 dB fractional bandwidth of 3% is designed and simulated. The circuit model and layout results show good performances of high selectivity, less than 1.7 dB insertion loss, and better than 16 dB in-band return loss. The common microstrip SOLR and the microstrip hair-pin resonators used in implementing the proposed integrated FPS ensures that an overall compact size of 0.34 λg × 0.11 λg was achieved, where λg is the guided-wavelength of the 50 Ω microstrip line at the fundamental resonant frequency of the FPS passband. Full article
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Open AccessReview
Computer-Human Interaction and Collaboration: Challenges and Prospects
Electronics 2021, 10(5), 616; https://doi.org/10.3390/electronics10050616 - 06 Mar 2021
Viewed by 496
Abstract
Through a series of projects carried out by the Computer–Human Interaction and COllaboration (CHICO) group of the University of Castilla-La Mancha, some proposals are presented to improve the current e-Learning systems by making use of different paradigms of human-computer interaction. Synchronous and asynchronous [...] Read more.
Through a series of projects carried out by the Computer–Human Interaction and COllaboration (CHICO) group of the University of Castilla-La Mancha, some proposals are presented to improve the current e-Learning systems by making use of different paradigms of human-computer interaction. Synchronous and asynchronous collaborative systems, ubiquitous computing, and augmented reality can improve the current learning environments. The use of artificial intelligence mechanisms for both learner support and assessment complements these techniques. Emphasis is also placed on the use of automatic application generation techniques using models. Full article
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Open AccessArticle
Improved RTT Fairness of BBR Congestion Control Algorithm Based on Adaptive Congestion Window
Electronics 2021, 10(5), 615; https://doi.org/10.3390/electronics10050615 - 06 Mar 2021
Viewed by 342
Abstract
To alleviate the lower performance of Transmission Control Protocol (TCP) congestion control over complex network, especially the high latency and packet loss scenario, Google proposed the Bottleneck Bandwidth and Round-trip propagation time (BBR) congestion control algorithm. In contrast with other TCP congestion control [...] Read more.
To alleviate the lower performance of Transmission Control Protocol (TCP) congestion control over complex network, especially the high latency and packet loss scenario, Google proposed the Bottleneck Bandwidth and Round-trip propagation time (BBR) congestion control algorithm. In contrast with other TCP congestion control algorithms, BBR adjusted transfer data by maximizing delivery rate and minimizing delay. However, some evaluation experiments have shown that the persistent queues formation and retransmissions in the bottleneck can lead to serious fairness issues between BBR flows with different round-trip times (RTTs). They pointed out that small RTT differences cause unfairness in the throughput of BBR flows and flows with longer RTT can obtain higher bandwidth when competing with the shorter RTT flows. In order to solve this fairness problem, an adaptive congestion window of BBR is proposed, which adjusts the congestion window gain of each BBR flow in network load. The proposed algorithms alleviate the RTT fairness issue by controlling the upper limit of congestion window according to the delivery rate and queue status. In the Network Simulator 3 (NS3) simulation experiment, it shows that the adaptive congestion window of BBR (BBR-ACW) congestion control algorithm improves the fairness by more than 50% and reduces the queuing delay by 54%, compared with that of the original BBR in different buffer sizes. Full article
(This article belongs to the Section Networks)
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Open AccessArticle
On Coding and Decoding Reconfigurable Radiation Pattern Modulation Symbols
Electronics 2021, 10(5), 614; https://doi.org/10.3390/electronics10050614 - 06 Mar 2021
Viewed by 312
Abstract
In this paper, we propose the theoretical framework for a reconfigurable radiation pattern modulation (RRPM) scheme, which is reminiscent of the index modulation technique. In the proposed scheme, information is encoded using far-field radiation patterns generated by a set of programmable radiating elements. [...] Read more.
In this paper, we propose the theoretical framework for a reconfigurable radiation pattern modulation (RRPM) scheme, which is reminiscent of the index modulation technique. In the proposed scheme, information is encoded using far-field radiation patterns generated by a set of programmable radiating elements. A considerable effort has been invested to allow for high transmission of the reconfigurable radiation pattern symbols; yet, the receiving system has received little attention and has always been considered ideal. Depending on the number of receivers and their respective positions, two variables are considered here for data transmission: the sampling resolution and the fraction of the covered space by the receiving antennas. Hence, we quantitatively investigate their effect on the bit-error-rate (BER) by making use of a limited number of measurements that approximate the behavior of the system under real-field conditions. Full article
(This article belongs to the Special Issue Innovative Technologies in Telecommunication)
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Open AccessFeature PaperArticle
Ultra-Short Window Length and Feature Importance Analysis for Cognitive Load Detection from Wearable Sensors
Electronics 2021, 10(5), 613; https://doi.org/10.3390/electronics10050613 - 06 Mar 2021
Cited by 1 | Viewed by 365
Abstract
Human cognitive capabilities are under constant pressure in the modern information society. Cognitive load detection would be beneficial in several applications of human–computer interaction, including attention management and user interface adaptation. However, current research into accurate and real-time biosignal-based cognitive load detection lacks [...] Read more.
Human cognitive capabilities are under constant pressure in the modern information society. Cognitive load detection would be beneficial in several applications of human–computer interaction, including attention management and user interface adaptation. However, current research into accurate and real-time biosignal-based cognitive load detection lacks understanding of the optimal and minimal window length in data segmentation which would allow for more timely, continuous state detection. This study presents a comparative analysis of ultra-short (30 s or less) window lengths in cognitive load detection with a wearable device. Heart rate, heart rate variability, galvanic skin response, and skin temperature features are extracted at six different window lengths and used to train an Extreme Gradient Boosting classifier to detect between cognitive load and rest. A 25 s window showed the highest accury (67.6%), which is similar to earlier studies using the same dataset. Overall, model accuracy tended to decrease as the window length decreased, and lowest performance (60.0%) was observed with a 5 s window. The contribution of different physiological features to the classification performance and the most useful features that react in short windows are also discussed. The analysis provides a promising basis for future real-time applications with wearable sensors. Full article
(This article belongs to the Special Issue Artificial Intelligence and Ambient Intelligence)
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Open AccessFeature PaperArticle
Efficient Design Strategy for Optimizing the Settling Time in Three-Stage Amplifiers Including Small- and Large-Signal Behavior
Electronics 2021, 10(5), 612; https://doi.org/10.3390/electronics10050612 - 06 Mar 2021
Viewed by 337
Abstract
An analytical criterion for the optimization of the small-signal settling time in three-stage amplifiers is carried out. The criterion is based on making equal the two exponential decays of the step response. Including slew-rate effects, a useful design strategy for the design of [...] Read more.
An analytical criterion for the optimization of the small-signal settling time in three-stage amplifiers is carried out. The criterion is based on making equal the two exponential decays of the step response. Including slew-rate effects, a useful design strategy for the design of three-stage operational transconductance amplifier is provided. Extensive time-domain simulations on a transistor-level design in a 65-nm CMOS process confirm the validity of the proposed approach. Full article
(This article belongs to the Section Microelectronics and Optoelectronics)
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Open AccessArticle
Palliation of Four-Wave Mixing in Optical Fibers Using Improved DSP Receiver
Electronics 2021, 10(5), 611; https://doi.org/10.3390/electronics10050611 - 05 Mar 2021
Viewed by 312
Abstract
A long haul optical communication system (LHOCS) is one of the key resources to fulfill the higher capacity requirements in future communication networks. To launch LHOCS, the system mainly faces high order nonlinear effects. The four-wave mixing (FWM) is one of the major [...] Read more.
A long haul optical communication system (LHOCS) is one of the key resources to fulfill the higher capacity requirements in future communication networks. To launch LHOCS, the system mainly faces high order nonlinear effects. The four-wave mixing (FWM) is one of the major nonlinear effects, which limits the transmission distance. Therefore, in this paper, an advanced duo-binary (DB) modulation scheme-based system is evaluated by employing an improved digital signal processing (IDSP) approach at the receiver side to suppress the FWM effect. In addition, an analytical analysis is also performed for the proposed system. To observe the difference between the IDSP and conventional digital signal processing (DSP), the various performance metrics such as bit error rate (BER), Q-factor, and optical signal-to-noise ratio (OSNR) parameters are evaluated. Variable channel spacing along with polarization mode dispersion (PMD) are analyzed at several ranges of input powers and fiber lengths. The analytical and simulation-based calculations exhibit the effectiveness of the proposed model and hence, FWM effect are compensated to achieve 500 km optical fiber propagation range with a BER below 106. Full article
(This article belongs to the Special Issue Theory and Applications in Digital Signal Processing)
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Open AccessArticle
Partitioning Power Grid for the Design of the Zonal Energy Market While Preserving Control Area Constraints
Electronics 2021, 10(5), 610; https://doi.org/10.3390/electronics10050610 - 05 Mar 2021
Viewed by 215
Abstract
The use of a zonal structure for energy markets across the globe is expanding; however the debate on how to effectively partition the grid into bidding zones is still open for discussion. One of the factors that needs to be addressed in the [...] Read more.
The use of a zonal structure for energy markets across the globe is expanding; however the debate on how to effectively partition the grid into bidding zones is still open for discussion. One of the factors that needs to be addressed in the process of bidding zones’ delimitation is the transmission system operators control areas. Merging parts of different control areas into one bidding zone can lead to multiple problems, ranging from political, through grid security concerns, to reserve control issues. To address it, this paper presents a novel grid partitioning method aimed at bidding zones delimitation that is based on clustering the power grid using an extended version of the standard agglomerative clustering. The proposed solution adds additional clustering rules when constructing the dendrogram in order to take into account the control areas. The algorithm is applied to the data which represents the locational marginal prices obtained from optimal power flow analysis. Full article
(This article belongs to the Special Issue Applied Data Mining)
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Open AccessArticle
A Comprehensive Investigation of the Properties of a Five-Phase Induction Motor Operating in Hazardous States in Various Connections of Stator Windings
Electronics 2021, 10(5), 609; https://doi.org/10.3390/electronics10050609 - 05 Mar 2021
Viewed by 343
Abstract
This paper examines the properties of a multi-phase drive for EV (electric vehicles) and HEV (hybrid-electric vehicles) using a simulation model in the Matlab/Simulink environment and verifies the findings by experimental measurements on a real motor. The paper studies a five-phase induction motor, [...] Read more.
This paper examines the properties of a multi-phase drive for EV (electric vehicles) and HEV (hybrid-electric vehicles) using a simulation model in the Matlab/Simulink environment and verifies the findings by experimental measurements on a real motor. The paper studies a five-phase induction motor, a suitable alternative for electric vehicles, due to its better properties such as better torque, smoother ripple, better fault tolerance, and the possibility of connecting stator windings to star, pentagon, and pentagram. The fundamentals of the article are to find out how this engine behaves in fault states, which can be called hazardous states. The paper presents a comprehensive evaluation of the decrease of mechanical power, torque, and power losses during motor operation without failure, in case of failure of one phase, and in case of failure of two adjacent phases and two non-adjacent phases, in different connections. In the simulations, the five-phase drive is powered from an ideal five-phase voltage source to verify the behavior of losses on the motor in fault conditions. Subsequently, the motor model is powered by a five-phase VSI, while the simulated waveforms are confirmed on a real motor, which is also powered by a five-phase VSI. The investigation results are the detection, which of the stator windings has better properties in the fault-free state and the case of fault states in operation. For which stator windings connection, it is most advantageous to design and dimension a five-phase induction motor. Full article
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Open AccessArticle
Development of Wearable Wireless Electrocardiogram Detection System using Bluetooth Low Energy
Electronics 2021, 10(5), 608; https://doi.org/10.3390/electronics10050608 - 05 Mar 2021
Viewed by 404
Abstract
Wearable monitoring devices can provide patients and doctors with the capability to measure bio-signals on demand. These systems provide enormous benefits for people with acute symptoms of serious health conditions. In this paper, we propose a novel method for collecting ECG signals using [...] Read more.
Wearable monitoring devices can provide patients and doctors with the capability to measure bio-signals on demand. These systems provide enormous benefits for people with acute symptoms of serious health conditions. In this paper, we propose a novel method for collecting ECG signals using two wireless wearable modules. The electric potential measured from a sub-module is transferred to the main module through Bluetooth Low Energy, and the collected values are simultaneously displayed in the form of a graph. This study describes the configuration and outcomes of the proposed system and discusses the important challenges associated with the functioning of the device. The proposed system had 84% signal similarity to that of other commercial products. As a band-type module was used on each wrist to check the signal, continuous observation of patients can be achieved without restricting their actions or causing discomfort. Full article
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Open AccessArticle
A UWB Antenna Array Integrated with Multimode Resonator Bandpass Filter
Electronics 2021, 10(5), 607; https://doi.org/10.3390/electronics10050607 - 05 Mar 2021
Viewed by 449
Abstract
This paper presents a novel design of a modified ultrawideband (UWB) antenna array integrated with a multimode resonator bandpass filter. First, a single UWB antenna is modified and studied, using a P-shape radiated patch instead of a full elliptical patch, for wide impedance [...] Read more.
This paper presents a novel design of a modified ultrawideband (UWB) antenna array integrated with a multimode resonator bandpass filter. First, a single UWB antenna is modified and studied, using a P-shape radiated patch instead of a full elliptical patch, for wide impedance bandwidth and high realized gain. Then, a two-element UWB antenna array is developed based on this modified UWB antenna with an inter-element spacing of 0.35 λL, in which λL is the free space wavelength at the lower UWB band edge of 3.1 GHz, compared to 0.27 λL of a reference UWB antenna array designed using a traditional elliptical patch shape. The partial ground plane is designed with a trapezoidal angle to enhance matching throughout the UWB frequency range. The mutual coupling reduction of a modified UWB antenna array enhances the reflection coefficient, bandwidth, and realized gain, maintaining the same size of 1.08 λ0 × 1.08 λ0 × 0.035 λ0 at 6.5 GHz center frequency as that of the reference UWB antenna array. The UWB antenna array performance is investigated at different inter-element spacing distances between the radiated elements. To add filtering capability to the UWB antenna array and eliminate interference from the out-of-band frequencies, a multimode resonator (MMR) bandpass filter (BPF) is incorporated in the feedline while maintaining a compact size. The measurement results showed a close agreement with simulated results. The proposed UWB filtering antenna array design achieved a wide fractional bandwidth of more than 109.87%, a high realized gain of more than 7.4 dBi, and a compact size of 1.08 λ0 × 1.08 λ0 × 0.035 λ0 at 6.5 GHz center frequency. These advantages make the proposed antenna suitable for UWB applications such as indoor tracking, radar systems and positioning applications. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
An SVD Approach for Estimating the Dimension of Phaseless Data on Multiple Arcs in Fresnel Zone
Electronics 2021, 10(5), 606; https://doi.org/10.3390/electronics10050606 - 05 Mar 2021
Cited by 1 | Viewed by 417
Abstract
In this article, we tackle the question of evaluating the dimension of the data space in the phase retrieval problem. With the aim to achieve this task, we first exploit the lifting technique to recast the quadratic model as a linear one. After [...] Read more.
In this article, we tackle the question of evaluating the dimension of the data space in the phase retrieval problem. With the aim to achieve this task, we first exploit the lifting technique to recast the quadratic model as a linear one. After that, we evaluate analytically the singular values of the lifting operator, and we quantify the dimension of the data space by counting the number of “significant” singular values. In the last part of the article, we show some numerical results in order to corroborate our analytical prediction on the singular values’ behavior of the lifting operator and on the dimension of the data space. The analysis is performed for a 2D scalar geometry consisting of an electric current strip whose square magnitude of the radiated field is observed on multiple arcs of circumference in Fresnel zone. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
On Multi-Scalar Multiplication Algorithms for Register-Constrained Environments
Electronics 2021, 10(5), 605; https://doi.org/10.3390/electronics10050605 - 05 Mar 2021
Viewed by 259
Abstract
A basic but expensive operation in the implementations of several famous public-key cryptosystems is the computation of the multi-scalar multiplication in a certain finite additive group defined by an elliptic curve. We propose an adaptive window method for the multi-scalar multiplication, which aims [...] Read more.
A basic but expensive operation in the implementations of several famous public-key cryptosystems is the computation of the multi-scalar multiplication in a certain finite additive group defined by an elliptic curve. We propose an adaptive window method for the multi-scalar multiplication, which aims to balance the computation cost and the memory cost under register-constrained environments. That is, our method can maximize the computation efficiency of multi-scalar multiplication according to any small, fixed number of registers provided by electronic devices. We further demonstrate that our method is efficient when five registers are available. Our method is further studied in detail in the case where it is combined with the non-adjacent form (NAF) representation and the joint sparse form (JSF) representation. One efficiency result is that our method with the proposed improved NAF n-bit representation on average requires 209n/432 point additions. To the best of our knowledge, this efficiency result is optimal compared with those of similar methods using five registers. Unlike the previous window methods, which store all possible values in the window, our method stores those with comparatively high probabilities to reduce the number of required registers. Full article
(This article belongs to the Special Issue Hardware Support for the Security of Computing Devices)
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