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Electronics, Volume 10, Issue 8 (April-2 2021) – 112 articles

Cover Story (view full-size image): Cyber-physical system complexity is increasing simultaneously with increased demands on quality and shortened time-to-market. To effectively support the development of such systems, we present languages and tools for comprehensive integrated model-based development that cover major phases such as requirement analysis, design, implementation, and maintenance. The model-based approach raises the level of abstraction and allows us to perform virtual prototyping by simulating and optimizing system models before building physical products. Moreover, open standards and open source implementations enable model portability, tool re-use and a broader deployment. In this paper, we present a general overview of the available solutions with a focus on Modelica/OpenModelica, Bloqqi, and Acumen and discuss the characteristics necessary for CPS modeling tools as well as future trends in CPS tool [...] Read more.
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Article
Automated Quantum Hardware Selection for Quantum Workflows
Electronics 2021, 10(8), 984; https://doi.org/10.3390/electronics10080984 - 20 Apr 2021
Cited by 2 | Viewed by 658
Abstract
The execution of a quantum algorithm typically requires various classical pre- and post-processing tasks. Hence, workflows are a promising means to orchestrate these tasks, benefiting from their reliability, robustness, and features, such as transactional processing. However, the implementations of the tasks may be [...] Read more.
The execution of a quantum algorithm typically requires various classical pre- and post-processing tasks. Hence, workflows are a promising means to orchestrate these tasks, benefiting from their reliability, robustness, and features, such as transactional processing. However, the implementations of the tasks may be very heterogeneous and they depend on the quantum hardware used to execute the quantum circuits of the algorithm. Additionally, today’s quantum computers are still restricted, which limits the size of the quantum circuits that can be executed. As the circuit size often depends on the input data of the algorithm, the selection of quantum hardware to execute a quantum circuit must be done at workflow runtime. However, modeling all possible alternative tasks would clutter the workflow model and require its adaptation whenever a new quantum computer or software tool is released. To overcome this problem, we introduce an approach to automatically select suitable quantum hardware for the execution of quantum circuits in workflows. Furthermore, it enables the dynamic adaptation of the workflows, depending on the selection at runtime based on reusable workflow fragments. We validate our approach with a prototypical implementation and a case study demonstrating the hardware selection for Simon’s algorithm. Full article
(This article belongs to the Special Issue Quantum Computing System Design and Architecture)
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Article
An Integrated Framework for Traceability and Impact Analysis in Requirements Verification of Cyber–Physical Systems
Electronics 2021, 10(8), 983; https://doi.org/10.3390/electronics10080983 - 20 Apr 2021
Viewed by 500
Abstract
In the field of model-based design of Cyber–Physical Systems (CPS), seamless traceability of the process, from requirements to models to simulation results, is becoming increasingly important. It can be used to support several activities such as variant handling, impact analysis, component reuse, software [...] Read more.
In the field of model-based design of Cyber–Physical Systems (CPS), seamless traceability of the process, from requirements to models to simulation results, is becoming increasingly important. It can be used to support several activities such as variant handling, impact analysis, component reuse, software maintenance and evolution, verification, and validation. Despite the fact that the relevance of traceability in the model-based design of CPSs is well known, current tools that support traceability management are inadequate in practice. The lack of comprehensive whole-lifecycle systems engineering support in a single tool is one of the main causes of such ineffective traceability management, where traceability relationships between artifacts are still manually generated and maintained. This paper aims at presenting an approach and a prototype for automatically generating and maintaining the appropriate traceability links between heterogeneous artifacts ranging from requirement models, through design models, down to simulation and verification results throughout the product life cycle in model-based design of CPSs. A use case study is presented to validate and illustrate the proposed method and prototype. Full article
(This article belongs to the Special Issue Tools and Languages for Object-Oriented Modeling and Simulation)
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Article
Herniated Lumbar Disc Generation and Classification Using Cycle Generative Adversarial Networks on Axial View MRI
Electronics 2021, 10(8), 982; https://doi.org/10.3390/electronics10080982 - 20 Apr 2021
Viewed by 492
Abstract
A frequent cause of lower back pain presenting with leg pain is a herniated lumbar intervertebral disc. A herniation or a herniated lumbar disc is a change of position of disc material (nucleus pulpous or annulus fibrosis). Usually, the lower back pain goes [...] Read more.
A frequent cause of lower back pain presenting with leg pain is a herniated lumbar intervertebral disc. A herniation or a herniated lumbar disc is a change of position of disc material (nucleus pulpous or annulus fibrosis). Usually, the lower back pain goes away within days or weeks. Regular treatment techniques for lower back pain include medication, exercises, relaxation methods and surgery. Back pain and back problems regularly occur in the lumbar region. The spinal canal is made up of vertebrae; each one protects the spinal nerves. Intervertebral discs and facet joints connect the vertebrae above and below. Groups of muscles and ligaments hold the vertebrae and the discs together. Muscles support the spine and the body weight, and they allow us to move. Pressure can result in excessive wear and tear of the other structures. For example, a common problem in the lower back is disc herniation. In this case, pressure on an intervertebral disc makes its center, the nucleus pulposus, protrude backwards and push against the spinal nerves, leading to lower back pain. Detection and classification are the two most important tasks in computer aided diagnosing systems. Detection of a herniated lumbar disc from magnetic resonance imaging (MRI) is a very difficult task for radiologist. The extraction of herniated discs has been achieved by different approaches such as active contours, region growing, watershed techniques, thresholding and deep learning. In this study, to detect intervertebral disc from axial MRIs we develop a method using generative adversarial networks (GANs), especially the CycleGAN model, to automatically generate and detect intervertebral disc and to classify the type of the herniated lumbar disc such as foraminal or median. We propose to explore the importance of axial view MRI to determine the herniation type. Accurately, GANs and other generative networks have created several ways to tackle different problems well known and challenging of medical image analysis, such as segmentation, reconstruction, data simulation, medical image de-noising, and classification. Moreover, their efficiency to synthesize images and data at unprecedented levels of realism also gives hope that the chronic scarcity of labeled data in the medical field can be resolved with the help of these generative models. In our case, having a database that contains several images is a very difficult task. In this paper, we put forward a new approach based on GANs, in order to solve the problem of lumbar intervertebral disc images reduction. This method is based especially on CycleGAN. Consequently, the essential objective of our work is to generate and automatically classify the herniation type as foraminal or median using GANs. Our computer aided diagnosis (CAD) system achieved a 97.2% accuracy on our dataset. This result represents a very high-performance results by providing the state of the art and our work utilizing the GANs technique. Our CAD is very effective and efficient for classifying herniations of lumbar intervertebral discs. Therefore, the contribution of this study appears in: firstly, the use of the CycleGAN model based on convolutional layers to detect and classify the herniation type (median or foraminal) in lumbar intervertebral discs, secondly, the use of axial view MRI in order to classify the type of the herniated intervertebral disc. The main objective of this paper is to help radiologists automatically recognize and classify herniated lumbar discs. Full article
(This article belongs to the Section Computer Science & Engineering)
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Article
Design and Analysis of a Symmetric Log Star Graph with a Smaller Network Cost Than Star Graphs
Electronics 2021, 10(8), 981; https://doi.org/10.3390/electronics10080981 - 20 Apr 2021
Viewed by 392
Abstract
Graphs are used as models to solve problems in fields such as mathematics, computer science, physics, and chemistry. In particular, torus, hypercube, and star graphs are popular when modeling the connection structure of processors in parallel computing because they are symmetric and have [...] Read more.
Graphs are used as models to solve problems in fields such as mathematics, computer science, physics, and chemistry. In particular, torus, hypercube, and star graphs are popular when modeling the connection structure of processors in parallel computing because they are symmetric and have a low network cost. Whereas a hypercube has a substantially smaller diameter than a torus, star graphs have been presented as an alternative to hypercubes because of their lower network cost. We propose a novel log star (LS) that is symmetric and has a lower network cost than a star graph. The LS is an undirected, recursive, and regular graph. In LSn, the number of nodes is n! while the degree is 2log2n − 1 and the diameter is 0.5n(log2n)2 + 0.75nlog2n. In this study, we analyze the basic topological properties of LS. We prove that LSn is a symmetrical connected graph and analyzed its subgraph characteristics. Then, we propose a routing algorithm and derive the diameter and network cost. Finally, the network costs of the LS and star graph-like networks are compared. Full article
(This article belongs to the Section Computer Science & Engineering)
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Article
Voice Assistant Application for Avoiding Sedentarism in Elderly People Based on IoT Technologies
Electronics 2021, 10(8), 980; https://doi.org/10.3390/electronics10080980 - 20 Apr 2021
Cited by 1 | Viewed by 705
Abstract
The rise in the use of virtual assistants such as Siri, Google Assistant, or Alexa among different sectors of society is facilitating access to information and services that were previously inconceivable due to the existing digital divide due to age. This situation allows [...] Read more.
The rise in the use of virtual assistants such as Siri, Google Assistant, or Alexa among different sectors of society is facilitating access to information and services that were previously inconceivable due to the existing digital divide due to age. This situation allows especially the elderly to perform tasks much more easily and to access applications and services that could be a challenge for them with other digital user interfaces. With this in mind, the EMERITI project aims to improve the lives of the elderly through the use of virtual assistants in different case studies. In this sense, virtual voice assistants along with the use of Internet of Things (IoT) technologies can contribute to avoid sedentarism in the elderly; however, it is necessary to address the problem of proactivity presented by the virtual assistants available in the market. This article presents a solution that, through the use of activity monitoring smart bracelets, IoT devices and virtual voice assistants allow the elderly to monitor their daily physical activity simply by using their voice and therefore prevent them from sedentary patterns. Finally, this study presents the technical results obtained after the deployment of the proposed system and discusses the main advantages and the current challenges of the use of virtual assistants in applications to prevent sedentary lifestyles in the elderly. Full article
(This article belongs to the Special Issue Ambient Assisted Living Technologies)
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Article
Towards Optimal Dissemination of Emergency Messages in Internet of Vehicles: A Dynamic Clustering-Based Approach
Electronics 2021, 10(8), 979; https://doi.org/10.3390/electronics10080979 - 19 Apr 2021
Cited by 1 | Viewed by 609
Abstract
In this paper, we target dissemination issues of emergency messages in a highly dynamic Internet of Vehicles (IoV) network. IoV is emerging as a new class of vehicular networks to optimize road safety as well as users’ comfort. In such a context, forwarding [...] Read more.
In this paper, we target dissemination issues of emergency messages in a highly dynamic Internet of Vehicles (IoV) network. IoV is emerging as a new class of vehicular networks to optimize road safety as well as users’ comfort. In such a context, forwarding emergency messages through vehicle-to-vehicle communications (V2V) plays a vital role in enabling road safety-related applications. For instance, when an accident occurs, forwarding such information in real time will help to avoid other accidents in addition to avoiding congestion of network traffic. Thus, dissemination of emergency information is a major concern. However, on the one hand, vehicle density has increased in the last decade which may lead to several issues including message collisions, broadcast storm, and the problem of hidden nodes. On the other hand, high mobility of vehicles and hence dynamic changes of network topology result in failure of dissemination of emergency packets. To overcome these problems, we propose a new dissemination scheme of emergency packets by vehicles equipped with both DSRC and cellular LTE wireless communication capabilities. Our scheme is based on a dynamic clustering strategy, which includes a new cluster head selection algorithm to deal with the broadcast storm problem. Furthermore, our selection algorithm enables not only the election of the most stable vehicles as cluster heads, and hence their exploitation in forwarding the emergency information, but also the avoidance of packet collisions. We simulated our scheme in an urban environment and compared it with other data dissemination schemes. Obtained results show the efficiency of our scheme in minimizing collision and broadcast storm problems, while improving latency, packet delivery ratio and data throughput, as compared to other schemes. Full article
(This article belongs to the Special Issue Emerging Wireless Vehicular Communications)
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Article
Few-Shot Learning with a Novel Voronoi Tessellation-Based Image Augmentation Method for Facial Palsy Detection
Electronics 2021, 10(8), 978; https://doi.org/10.3390/electronics10080978 - 19 Apr 2021
Cited by 1 | Viewed by 615
Abstract
Face palsy has adverse effects on the appearance of a person and has negative social and functional consequences on the patient. Deep learning methods can improve face palsy detection rate, but their efficiency is limited by insufficient data, class imbalance, and high misclassification [...] Read more.
Face palsy has adverse effects on the appearance of a person and has negative social and functional consequences on the patient. Deep learning methods can improve face palsy detection rate, but their efficiency is limited by insufficient data, class imbalance, and high misclassification rate. To alleviate the lack of data and improve the performance of deep learning models for palsy face detection, data augmentation methods can be used. In this paper, we propose a novel Voronoi decomposition-based random region erasing (VDRRE) image augmentation method consisting of partitioning images into randomly defined Voronoi cells as an alternative to rectangular based random erasing method. The proposed method augments the image dataset with new images, which are used to train the deep neural network. We achieved an accuracy of 99.34% using two-shot learning with VDRRE augmentation on palsy faces from Youtube Face Palsy (YFP) dataset, while normal faces are taken from Caltech Face Database. Our model shows an improvement over state-of-the-art methods in the detection of facial palsy from a small dataset of face images. Full article
(This article belongs to the Section Bioelectronics)
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Article
Neutral Point Clamped Transformer-Less Multilevel Converter for Grid-Connected Photovoltaic System
Electronics 2021, 10(8), 977; https://doi.org/10.3390/electronics10080977 - 19 Apr 2021
Cited by 1 | Viewed by 622
Abstract
Transformer-less (TL) inverter topologies have elicited further special treatment in photo-voltaic (PV) power system as they provide high efficiency and low cost. Neutral point clamped (NPC) multilevel-inverter (MLI) topologies-based transformer-less are being immensely used in grid-connected medium-voltage high-power claims. Unfortunately, these topologies such [...] Read more.
Transformer-less (TL) inverter topologies have elicited further special treatment in photo-voltaic (PV) power system as they provide high efficiency and low cost. Neutral point clamped (NPC) multilevel-inverter (MLI) topologies-based transformer-less are being immensely used in grid-connected medium-voltage high-power claims. Unfortunately, these topologies such as NPC-MLI, full-bridge inverter with DC bypass (FB-DCBP) suffer from the shoot-through problem on the bridge legs, which affect the reliability of the implementation. Based on the previous above credits, a T type neutral point clamped (TNP)—MLI (TNP-MLI) with transformer-less topology called TL-TNP-MLI is presented to be an alternate which can be suitable in the grid-connected PV power generation systems. The suggested TL-TNP-MLI topologies free from inverter bridge legs shoot-through burden, switching frequency common-mode current (CMC), and leakage current. The control system of the grid interface with hysteresis current control (HCC) strategy is proposed. The effectiveness of the proposed PV connected transformer-less TNP-MLI topology with different grid and PV scenario has been verified through the MATLAB/Simulink simulation model and field-programmable gate area (FPGA)-based experimental results for a 1.5 kW system. Full article
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Article
A Tandem Feature Extraction Approach for Arrhythmia Identification
Electronics 2021, 10(8), 976; https://doi.org/10.3390/electronics10080976 - 19 Apr 2021
Cited by 1 | Viewed by 473
Abstract
Heart disease is currently the leading cause of death in the world. The electrocardiogram (ECG) is the recording of the electrical activity generated by the heart. Its low cost and simplicity have made it an essential test for monitoring heart disease, especially for [...] Read more.
Heart disease is currently the leading cause of death in the world. The electrocardiogram (ECG) is the recording of the electrical activity generated by the heart. Its low cost and simplicity have made it an essential test for monitoring heart disease, especially for the identification of arrhythmias. With the advances in electronic technology, there are nowadays sensors that enable the recording of the ECG during the daily life of the patient and its wireless transmission to healthcare facilities. This type of information has a great potential to detect cardiac diseases in their early stages and to permit early interventions before the patient’s health deteriorates. However, to usefully exploit the large volume of information obtained from ambulatory ECG, pattern recognition techniques that are capable of automatically analyzing it are required. Tandem feature extraction techniques have proven to be useful for the processing of physiological parameters such as the electroencephalogram (EEG) and speech. However, to the best of our knowledge, they have never been applied to the ECG. In this paper, the utility of tandem feature extraction for the identification of arrhythmias is studied. The coefficients of a regression using Hermite functions are used to create a feature vector that represents the heartbeat. A multiple-layer perceptron (MLP) is trained using these features and its posterior probability outputs are used to extend the original feature vector. Finally, a Gaussian mixture model (GMM) is trained on the extended feature vectors, which is then used in a GMM-based arrhythmia identification system. This approach has been validated using the MIT-BIH Arrhythmia database. The accuracy of the Gaussian mixture model increased by 15.8% when applied over the extended feature vectors, compared to its application over the original feature vectors, showing the potential of tandem feature extraction for ECG analysis and arrhythmia identification. Full article
(This article belongs to the Special Issue Pattern Recognition and Applications)
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Article
Improving Emission Uniformity of InGaN/GaN-Based Vertical LEDs by Using Reflective ITO/Ag n-Contact
Electronics 2021, 10(8), 975; https://doi.org/10.3390/electronics10080975 - 19 Apr 2021
Viewed by 487
Abstract
We investigated the effect of Ti/Al and ITO/Ag n-type contacts on the emission uniformity and light output of different chip-size vertical-geometry light-emitting diodes (VLEDs) for vehicle headlamp application. The forward voltage of the Ti/Al-based reference VLEDs decreased from 3.38 to 3.20 V at [...] Read more.
We investigated the effect of Ti/Al and ITO/Ag n-type contacts on the emission uniformity and light output of different chip-size vertical-geometry light-emitting diodes (VLEDs) for vehicle headlamp application. The forward voltage of the Ti/Al-based reference VLEDs decreased from 3.38 to 3.20 V at 1500 mA with increasing chip size from (1280 × 1000 µm2) to (1700 × 1700 µm2), whereas that of the ITO/Ag-based samples changed from 3.37 to 3.15 V. Regardless of chip size, the ITO/Ag-based samples revealed higher light output power than the reference samples. For example, the ITO/Ag-based samples (chip size of 1700 × 1700 µm2) exhibited 3.4% higher light output power at 1500 mA than the reference samples. The ITO/Ag samples underwent less degradation in the Wall-plug efficiency (WPE) than the reference sample. For instance, the ITO/Ag-based samples (1700 × 1700 µm2) gave 4.8% higher WPE at 1500 mA than the reference samples. The ITO/Ag-based samples illustrated more uniform emission than the Ti/Al-based sample. Both the reference and ITO/Ag-based samples underwent no degradation when operated at 1500 mA for 1000 h. Full article
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Article
Compact Low-Cost Filter for 5G Interference Reduction in UHF Broadcasting Band
Electronics 2021, 10(8), 974; https://doi.org/10.3390/electronics10080974 - 19 Apr 2021
Viewed by 466
Abstract
The allocation of part of the UHF band to 4G and 5G services has generated the appearance of channel interferences over the digital terrestrial television frequency band. In order to reduce these interferences, this work presents a novel and efficient band-stop filter implemented [...] Read more.
The allocation of part of the UHF band to 4G and 5G services has generated the appearance of channel interferences over the digital terrestrial television frequency band. In order to reduce these interferences, this work presents a novel and efficient band-stop filter implemented using microstrip technology. The filter, designed with rectangular split-ring resonators etched in the ground plane, provides a cutoff frequency above channel 48 (694 MHz), a high roll-off rate of 44 dB in 56 MHz and a rejection bandwidth of 250 MHz that covers the upper UHF band occupied by 4G and 5G with rejection levels close to 35 dB. The filter is manufactured entirely over a printed circuit board without lumped elements to reduce production costs, fine tuning after the assembly stage and maintenance. Moreover, it presents a compact subwavelength size of only 0.07 λ × 0.17 λ to facilitate installation, whether at the input of the TV terminal or integrated with the balun at the rooftop antenna. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Review
State-of-the-Art Optical Devices for Biomedical Sensing Applications—A Review
Electronics 2021, 10(8), 973; https://doi.org/10.3390/electronics10080973 - 19 Apr 2021
Cited by 5 | Viewed by 1079
Abstract
Optical sensors for biomedical applications have gained prominence in recent decades due to their compact size, high sensitivity, reliability, portability, and low cost. In this review, we summarized and discussed a few selected techniques and corresponding technological platforms enabling the manufacturing of optical [...] Read more.
Optical sensors for biomedical applications have gained prominence in recent decades due to their compact size, high sensitivity, reliability, portability, and low cost. In this review, we summarized and discussed a few selected techniques and corresponding technological platforms enabling the manufacturing of optical biomedical sensors of different types. We discussed integrated optical biosensors, vertical grating couplers, plasmonic sensors, surface plasmon resonance optical fiber biosensors, and metasurface biosensors, Photonic crystal-based biosensors, thin metal films biosensors, and fiber Bragg grating biosensors as the most representative cases. All of these might enable the identification of symptoms of deadly illnesses in their early stages; thus, potentially saving a patient’s life. The aim of this paper was not to render a definitive judgment in favor of one sensor technology over another. We presented the pros and cons of all the major sensor systems enabling the readers to choose the solution tailored to their needs and demands. Full article
(This article belongs to the Special Issue Optical Sensing for Biomedical Applications)
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Article
A Distributed Edge-Based Scheduling Technique with Low-Latency and High-Bandwidth for Existing Driver Profiling Algorithms
Electronics 2021, 10(8), 972; https://doi.org/10.3390/electronics10080972 - 19 Apr 2021
Cited by 1 | Viewed by 396
Abstract
The gradual increase in latency-sensitive, real-time applications for embedded systems encourages users to share sensor data simultaneously. Streamed sensor data have deficient performance. In this paper, we propose a new edge-based scheduling method with high-bandwidth for decreasing driver-profiling latency. The proposed multi-level memory [...] Read more.
The gradual increase in latency-sensitive, real-time applications for embedded systems encourages users to share sensor data simultaneously. Streamed sensor data have deficient performance. In this paper, we propose a new edge-based scheduling method with high-bandwidth for decreasing driver-profiling latency. The proposed multi-level memory scheduling method places data in a key-value storage, flushes sensor data when the edge memory is full, and reduces the number of I/O operations, network latency, and the number of REST API calls in the edge cloud. As a result, the proposed method provides significant read/write performance enhancement for real-time embedded systems. In fact, the proposed application improves the number of requests per second by 3.5, 5, and 4 times, respectively, compared with existing light-weight FCN-LSTM, FCN-LSTM, and DeepConvRNN Attention solutions. The proposed application also improves the bandwidth by 5.89, 5.58, and 4.16 times respectively, compared with existing light-weight FCN-LSTM, FCN-LSTM, and DeepConvRNN Attention solutions. Full article
(This article belongs to the Special Issue Real-Time Control of Embedded Systems)
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Article
State Estimation Using a Randomized Unscented Kalman Filter for 3D Skeleton Posture
Electronics 2021, 10(8), 971; https://doi.org/10.3390/electronics10080971 - 19 Apr 2021
Viewed by 446
Abstract
In this study, we propose a method for minimizing the noise of Kinect sensors for 3D skeleton estimation. Notably, it is difficult to effectively remove nonlinear noise when estimating 3D skeleton posture; however, the proposed randomized unscented Kalman filter reduces the nonlinear temporal [...] Read more.
In this study, we propose a method for minimizing the noise of Kinect sensors for 3D skeleton estimation. Notably, it is difficult to effectively remove nonlinear noise when estimating 3D skeleton posture; however, the proposed randomized unscented Kalman filter reduces the nonlinear temporal noise effectively through the state estimation process. The 3D skeleton data can then be estimated at each step by iteratively passing the posterior state during the propagation and updating process. Ultimately, the performance of the proposed method for 3D skeleton estimation is observed to be superior to that of conventional methods based on experimental results. Full article
(This article belongs to the Special Issue Multimedia Systems and Signal Processing)
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Article
A Tightly-Coupled Positioning System of Online Calibrated RGB-D Camera and Wheel Odometry Based on SE(2) Plane Constraints
Electronics 2021, 10(8), 970; https://doi.org/10.3390/electronics10080970 - 19 Apr 2021
Viewed by 486
Abstract
The emergence of Automated Guided Vehicle (AGV) has greatly increased the efficiency of the transportation industry, which put forward the urgent requirement for the accuracy and ease of use of 2D planar motion robot positioning. Multi-sensor fusion positioning has gradually become an important [...] Read more.
The emergence of Automated Guided Vehicle (AGV) has greatly increased the efficiency of the transportation industry, which put forward the urgent requirement for the accuracy and ease of use of 2D planar motion robot positioning. Multi-sensor fusion positioning has gradually become an important technical route to improve overall efficiency when dealing with AGV positioning. As a sensor directly acquiring depth, the RGB-D camera has received extensive attention in indoor positioning in recent years, while wheel odometry is the sensor that comes with most two-dimensional planar motion robots, and its parameters will not change over time. Both the RGB-D camera and the wheel odometry are commonly used sensors for indoor robot positioning, but the existing research on the fusion of RGB-D and wheel odometry is limited based on classic filtering algorithms; few fusion solutions based on optimization algorithm of them are available at present. To ensure the practicability and greatly improve the accuracy of RGB-D and odometry fusion positioning scheme, this paper proposed a tightly-coupled positioning scheme of online calibrated RGB-D camera and wheel odometry based on SE(2) plane constraints. Experiments have proved that the angle accuracy of the extrinsic parameter in the calibration part is less than 0.5 degrees, and the displacement of the extrinsic parameter reaches the millimeter level. The field-test positioning accuracy of the positioning system we proposed having reached centimeter-level on the dataset without pre-calibration, which is better than ORB-SLAM2 relying solely on RGB-D cameras. The experimental results verify the excellent performance of the frame in positioning accuracy and ease of use and prove that it can be a potential promising technical solution in the field of two-dimensional AGV positioning. Full article
(This article belongs to the Section Systems & Control Engineering)
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Article
Polarization-Encoded Fully-Phase Encryption Using Transport-of-Intensity Equation
Electronics 2021, 10(8), 969; https://doi.org/10.3390/electronics10080969 - 19 Apr 2021
Viewed by 450
Abstract
In this study, we propose a novel method to encrypt fully-phase information combining the concepts of the transport of intensity equation and spatially variant polarization encoding. The transport of intensity equation is a non-iterative and non-interferometric phase-retrieval method which recovers the phase information [...] Read more.
In this study, we propose a novel method to encrypt fully-phase information combining the concepts of the transport of intensity equation and spatially variant polarization encoding. The transport of intensity equation is a non-iterative and non-interferometric phase-retrieval method which recovers the phase information from defocused intensities. Spatially variant polarization encoding employs defocused intensity measurements. The proposed cryptosystem uses a two-step optical experimentation process—primarily, a simple set-up for defocused intensities recording for phase retrieval and then a set-up for encoding. Strong security, convenient intensity-based measurements, and noise-free decryption are the main features of the proposed method. The simulation results have been presented in support of the proposed idea. However, the TIE section of the cryptosystem, as of now, has been experimentally demonstrated for micro-lens. Full article
(This article belongs to the Special Issue Compressive Optical Image Encryption)
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Article
Semi-Supervised Extreme Learning Machine Channel Estimator and Equalizer for Vehicle to Vehicle Communications
Electronics 2021, 10(8), 968; https://doi.org/10.3390/electronics10080968 - 19 Apr 2021
Cited by 1 | Viewed by 560
Abstract
Wireless vehicular communications are a promising technology. Most applications related to vehicular communications aim to improve road safety and have special requirements concerning latency and reliability. The traditional channel estimation techniques used in the IEEE 802.11 standard do not properly perform over vehicular [...] Read more.
Wireless vehicular communications are a promising technology. Most applications related to vehicular communications aim to improve road safety and have special requirements concerning latency and reliability. The traditional channel estimation techniques used in the IEEE 802.11 standard do not properly perform over vehicular channels. This is because vehicular communications are subject to non-stationary, time-varying, frequency-selective wireless channels. Therefore, the main goal of this work is the introduction of a new channel estimation and equalization technique based on a Semi-supervised Extreme Learning Machine (SS-ELM) in order to address the harsh characteristics of the vehicular channel and improve the performance of the communication link. The performance of the proposed technique is compared with traditional estimators, as well as state-of-the-art machine-learning-based algorithms over an urban scenario setup in terms of bit error rate. The proposed SS-ELM scheme outperformed the extreme learning machine and the fully complex extreme learning machine algorithms for the evaluated scenarios. Compared to traditional techniques, the proposed SS-ELM scheme has a very similar performance. It is also observed that, although the SS-ELM scheme requires the largest operation time among the evaluated techniques, its execution time is still far away from the latency requirements specified by the standard for safety applications. Full article
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Article
Electrical Characterization of Conductive Threads for Textile Electronics
Electronics 2021, 10(8), 967; https://doi.org/10.3390/electronics10080967 - 19 Apr 2021
Cited by 2 | Viewed by 619
Abstract
In recent years, advancements in technology are constantly driving the miniaturization of electronic devices, not only in the renowned domain of Internet-of-Things but also in other fields such as that of flexible and textile electronics. As the latter forms a great ecosystem for [...] Read more.
In recent years, advancements in technology are constantly driving the miniaturization of electronic devices, not only in the renowned domain of Internet-of-Things but also in other fields such as that of flexible and textile electronics. As the latter forms a great ecosystem for new devices, that could be functional such as heating garments or sensory, many suppliers have already started producing and bringing to market conductive threads that can be used by researchers and the mass public for their work. However, to date, no extensive characterization has been carried out with respect to the electrical performance of such threads and that is what this article is aiming to amend. Four commercially available threads by two different suppliers were put under test, to establish their limitations in terms of maximum power handling, both continuous and instantaneous. They were subsequently examined at a microscopic scale as well, to verify any potential caveats in their design, and any hidden limitations. A preliminary profile for each of the four threads was successfully established. Full article
(This article belongs to the Special Issue Textile and Wearable Antennas)
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Article
Design and Modeling of a Robust Sensorless Control System for a Linear Permanent Magnet Synchronous Motor
Electronics 2021, 10(8), 966; https://doi.org/10.3390/electronics10080966 - 18 Apr 2021
Viewed by 774
Abstract
The paper is concerned with designing an effective controller for a linear tubular homopolar (LT-H) motor type. The construction and operation of the LT-H motor are first described in detail. Then, the motor model is represented in the direct-quadrature (d-q) axes in order [...] Read more.
The paper is concerned with designing an effective controller for a linear tubular homopolar (LT-H) motor type. The construction and operation of the LT-H motor are first described in detail. Then, the motor model is represented in the direct-quadrature (d-q) axes in order to facilitate the design of the control loops. The designed control system consists of two main loops: the current control loop and velocity adaptation loop. The determination of the regulator’s gains is accomplished through deriving and analyzing the transfer functions of the loops. To enhance the system’s robustness, a robust variable estimator is designed to observe the velocity and stator resistance. Different performance evaluation tests are performed using MATLAB/Simulink software to validate the controller’s robustness for variable-speed operation and load force changes as well. The obtained results reveal the appropriate dynamics of the motor thanks to the well-designed control system. Full article
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Article
Wireless Powered Mobile Edge Computing Systems: Simultaneous Time Allocation and Offloading Policies
Electronics 2021, 10(8), 965; https://doi.org/10.3390/electronics10080965 - 18 Apr 2021
Cited by 2 | Viewed by 601
Abstract
To improve the computational power and limited battery capacity of mobile devices (MDs), wireless powered mobile edge computing (MEC) systems are gaining much importance. In this paper, we consider a wireless powered MEC system composed of one MD and a hybrid access point [...] Read more.
To improve the computational power and limited battery capacity of mobile devices (MDs), wireless powered mobile edge computing (MEC) systems are gaining much importance. In this paper, we consider a wireless powered MEC system composed of one MD and a hybrid access point (HAP) attached to MEC. Our objective is to achieve a joint time allocation and offloading policy simultaneously. We propose a cost function that considers both the energy consumption and the time delay of an MD. The proposed algorithm, joint time allocation and offload policy (JTAOP), is used to train a neural network for reducing the complexity of our algorithm that depends on the resolution of time and the number of components in a task. The numerical results are compared with three benchmark schemes, namely, total local computation, total offloading and partial offloading. Simulations show that the proposed algorithm performs better in producing the minimum cost and energy consumption as compared to the considered benchmark schemes. Full article
(This article belongs to the Section Computer Science & Engineering)
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Editorial
Antennas and Propagation Aspects for Emerging Wireless Communication Technologies
Electronics 2021, 10(8), 964; https://doi.org/10.3390/electronics10080964 - 18 Apr 2021
Viewed by 419
Abstract
The increasing demand for high data rate applications and the delivery of zero-latency multimedia content drives technological evolutions towards the design and implementation of next-generation broadband wireless networks [...] Full article
Article
A Bayesian Optimization Approach for Multi-Function Estimation for Environmental Monitoring Using an Autonomous Surface Vehicle: Ypacarai Lake Case Study
Electronics 2021, 10(8), 963; https://doi.org/10.3390/electronics10080963 - 18 Apr 2021
Cited by 1 | Viewed by 660
Abstract
Bayesian optimization is a sequential method that can optimize a single and costly objective function based on a surrogate model. In this work, we propose a Bayesian optimization system dedicated to monitoring and estimating multiple water quality parameters simultaneously using a single autonomous [...] Read more.
Bayesian optimization is a sequential method that can optimize a single and costly objective function based on a surrogate model. In this work, we propose a Bayesian optimization system dedicated to monitoring and estimating multiple water quality parameters simultaneously using a single autonomous surface vehicle. The proposed work combines different strategies and methods for this monitoring task, evaluating two approaches for acquisition function fusion: the coupled and the decoupled techniques. We also consider dynamic parametrization of the maximum measurement distance traveled by the ASV so that the monitoring system balances the total number of measurements and the total distance, which is related to the energy required. To evaluate the proposed approach, the Ypacarai Lake (Paraguay) serves as the test scenario, where multiple maps of water quality parameters, such as pH and dissolved oxygen, need to be obtained efficiently. The proposed system is compared with the predictive entropy search for multi-objective optimization with constraints (PESMOC) algorithm and the genetic algorithm (GA) path planning for the Ypacarai Lake scenario. The obtained results show that the proposed approach is 10.82% better than other optimization methods in terms of R2 score with noiseless measurements and up to 17.23% better when the data are noisy. Additionally, the proposed approach achieves a good average computational time for the whole mission when compared with other methods, 3% better than the GA technique and 46.5% better than the PESMOC approach. Full article
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Article
Further Improvement of Customized Vibration Generator for Machine–Human Feedbacks with the Help of Resonant Networks
Electronics 2021, 10(8), 962; https://doi.org/10.3390/electronics10080962 - 17 Apr 2021
Cited by 2 | Viewed by 419
Abstract
Modern industrial, household and other equipment include sophisticated power mechanisms and complicated control solutions and require tighter human–machine–human interaction, forming the structures known as cyber–physical–human systems. Their significant parts are human–machine command links and machine–human feedbacks. Such systems are found in medicine, for [...] Read more.
Modern industrial, household and other equipment include sophisticated power mechanisms and complicated control solutions and require tighter human–machine–human interaction, forming the structures known as cyber–physical–human systems. Their significant parts are human–machine command links and machine–human feedbacks. Such systems are found in medicine, for example, in orthopedics, where they are important for operation and functional abilities of orthopedic devices—smart wheelchairs, verticalizers, prosthesis, rehabilitation units, etc. The mentioned feedbacks may be implemented based on the haptic perceptions that require vibration actuators. In orthopedics, such actuators can also be used for diagnostic purposes. This research brings forward the idea of the use of resonant operation of the driver of vibration actuator. The corresponding driver has been built and experimentally tested. It has been found that (1) the point of maximal current is actually defined by the resonant frequency, (2) change of the capacitance allows shifting of the point of maximal current output and (3) damping factors make the above-described effect less obvious. Further development of the proposed idea requires a comprehensive comparison of four-quadrant and two-quadrant schemes in this application and development of a real-time programmable capacitor pack consisting of several binary weighted capacitors and a commutating circuit, which is installable to these schemes. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Article
Multiple Use SiPM Integrated Circuit (MUSIC) for Large Area and High Performance Sensors
Electronics 2021, 10(8), 961; https://doi.org/10.3390/electronics10080961 - 17 Apr 2021
Viewed by 494
Abstract
The 8-channel Multiple Use Silicon Photo-multiplier (SiPM) Integrated Circuit (MUSIC) Application specific integrated circuit (ASIC) for SiPM anode readout has been designed for applications where large photo-detection areas are required. MUSIC offers three main features: (1) Sum of the eight input channels using [...] Read more.
The 8-channel Multiple Use Silicon Photo-multiplier (SiPM) Integrated Circuit (MUSIC) Application specific integrated circuit (ASIC) for SiPM anode readout has been designed for applications where large photo-detection areas are required. MUSIC offers three main features: (1) Sum of the eight input channels using a differential output driver, (2) eight individual single ended (SE) analog outputs, and (3) eight individual SE binary outputs using a time over threshold technique. Each functionality, summation and individual readout includes a selectable dual-gain configuration. Moreover, the signal sum implements a dual-gain output providing a 15-bit dynamic range. The circuit contains a tunable pole zero cancellation of the SiPM recovery time constant to deal with most of the available SiPM devices in the market. Experimental tests show how MUSIC can linearly sum signals from different SiPMs and distinguish even a few photons. Additionally, it provides a single photon output pulse width at half maximum (FWHM) between 5–10 ns for the analog output and a single-photon time resolution (SPTR) around 118 ps sigma using a Hamamatsu SiPM S13360-3075CS for the binary output. Lastly, the summation mode has a power consumption of ≈200 mW, whereas the individual readout consumes ≈30 mW/ch. Full article
(This article belongs to the Special Issue Advances in Sensor Readout Electronics for Precise Timing)
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Article
Sheet Resistance Measurements of Conductive Thin Films: A Comparison of Techniques
Electronics 2021, 10(8), 960; https://doi.org/10.3390/electronics10080960 - 17 Apr 2021
Viewed by 549
Abstract
Conductive thin films are an essential component of many electronic devices. Measuring their conductivity accurately is necessary for quality control and process monitoring. We compare conductivity measurements on films for flexible electronics using three different techniques: four-point probe, microwave resonator and terahertz time-domain [...] Read more.
Conductive thin films are an essential component of many electronic devices. Measuring their conductivity accurately is necessary for quality control and process monitoring. We compare conductivity measurements on films for flexible electronics using three different techniques: four-point probe, microwave resonator and terahertz time-domain spectroscopy. Multiple samples were examined, facilitating the comparison of the three techniques. Sheet resistance values at DC, microwave and terahertz frequencies were obtained and were found to be in close agreement. Full article
(This article belongs to the Section Microelectronics)
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Review
Effective Cloud Resource Utilisation in Cloud ERP Decision-Making Process for Industry 4.0 in the United States
Electronics 2021, 10(8), 959; https://doi.org/10.3390/electronics10080959 - 16 Apr 2021
Viewed by 687
Abstract
Cloud enterprise resource planning (C-ERP) represents an evolution of traditional ERP, which also offers the advantages of cloud computing (CC) such as ease of use and resource elasticity. This article presents the opportunities and challenges of the C-ERP adoption for industry 4.0 in [...] Read more.
Cloud enterprise resource planning (C-ERP) represents an evolution of traditional ERP, which also offers the advantages of cloud computing (CC) such as ease of use and resource elasticity. This article presents the opportunities and challenges of the C-ERP adoption for industry 4.0 in the United States as well as the factors that boost or hinder such a decision. The quantitative research method is used to gather the predictor factors and correlation amongst them. An online survey questionnaire received 109 responses, mainly decision-makers and professionals from the US consumer goods industry. Statistical analysis has been carried out to rank the different levels of influence in the C-ERP adoption decision. The predictor’s complexity and regulatory compliance positively influence C-ERP private service deployment, whereas technology readiness is a good predictor of community service deployment. This paper also proposes a decision support system (DSS), tailored to industry 4.0, and aimed at assisting decision-makers in adopting C-ERP as an effective resource for decision-making. The DSS is built upon the predictors using the analytic hierarchy process (AHP) and it supports decision-makers in the selection of services and deployment models for C-ERP as a resource. Full article
(This article belongs to the Special Issue Resource Management in Cloud/Edge Computing)
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Article
Investigation on Thermal Resistance and Capacitance Characteristics of a Highly Integrated Power Control Unit Module
Electronics 2021, 10(8), 958; https://doi.org/10.3390/electronics10080958 - 16 Apr 2021
Viewed by 430
Abstract
With the increasing integration density of power control unit (PCU) modules, more functional power converter units are integrated into a single module for applications in electric vehicles or hybrid electric vehicles (EVs/HEVs). Different types of power dies with different footprints are usually placed [...] Read more.
With the increasing integration density of power control unit (PCU) modules, more functional power converter units are integrated into a single module for applications in electric vehicles or hybrid electric vehicles (EVs/HEVs). Different types of power dies with different footprints are usually placed closely together. Due to the constraints from the placement of power dies and liquid cooling schemes, heat-flow paths from the junction to coolant are possibly inconsistent for power dies, resulting in different thermal resistance and capacitance (RC) characteristics of power dies. This presents a critical challenge for optimal liquid cooling at a low cost. In this paper, a highly integrated PCU module is developed for application in EVs/HEVs. The underlying mechanism of the inconsistent RC characteristics of power dies for the developed PCU module is revealed by experiments and simulations. It is found that the matching placement design of power dies with a heat sink structure and liquid cooler, as well as a liquid cooling scheme, can alleviate the inconsistent RC characteristics of power dies in highly integrated PCU modules. The findings in this paper provide valuable guidance for the design of highly integrated PCU modules. Full article
(This article belongs to the Section Electrical and Autonomous Vehicles)
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Article
A Study to Resist Conduced Interference from GIS Bus-Charging Currents Switching for Electronic Current Transformer
Electronics 2021, 10(8), 957; https://doi.org/10.3390/electronics10080957 - 16 Apr 2021
Viewed by 431
Abstract
In this paper, we study the conducted interference to an electronic current transformer introduced in the process of bus-charging currents which are caused by switching a gas insulated switchgear (GIS) disconnector. To cope with these issues, the EMTP-ATP and Matlab/Simulink software are used [...] Read more.
In this paper, we study the conducted interference to an electronic current transformer introduced in the process of bus-charging currents which are caused by switching a gas insulated switchgear (GIS) disconnector. To cope with these issues, the EMTP-ATP and Matlab/Simulink software are used to carry out equivalent modeling simulations and experimental research, respectively. More specifically, the very fast transient current generated by disconnector switching (DS) is used as the input source of the equivalent simulation model of the Rogowski coil, and the characteristics of conducted interference waveforms of the Rogowski coil, the active integrator and filter outputs under single and multiple breakdowns are analyzed step by step. Moreover, several anti-interference methods are proposed to improve the resistance to the high-voltage and high-frequency conducted interference for the Rogowski coil, such as reducing the Rogowski cut-off frequency, increasing the transient voltage suppressor (TVS), active filter, and Cy capacitor. Besides, the study also reveals that the residual charge of the integral capacitor will discharge with a time constant τ = 1 s after arc quenching with the first-order discharge circuit, which is composed of the feedback resistance and the integral capacitor C. Lastly, the experimental results demonstrate the correctness of the modeling method proposed in this paper and the effectiveness of anti-interference measures. Full article
(This article belongs to the Special Issue Electromagnetic Interference and Compatibility, Volume II)
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Article
TID Circuit Simulation in Nanowire FETs and Nanosheet FETs
Electronics 2021, 10(8), 956; https://doi.org/10.3390/electronics10080956 - 16 Apr 2021
Viewed by 420
Abstract
In this study, the effects of the total ionizing dose (TID) on a nanowire (NW) field-effect transistor (FET) and a nanosheet (NS) FET were analyzed. The devices have Gate-all-around (GAA) structure that are less affected by TID effects because GAA structures have better [...] Read more.
In this study, the effects of the total ionizing dose (TID) on a nanowire (NW) field-effect transistor (FET) and a nanosheet (NS) FET were analyzed. The devices have Gate-all-around (GAA) structure that are less affected by TID effects because GAA structures have better gate controllability than previously proposed structures, such as planar MOSFETs and FinFETs. However, even for GAA devices with the same channel cross-sectional area and equivalent oxide thickness, structural differences can exist, which can result in different tolerances of TID effects. To observe the device and circuit operation characteristics of these GAA devices with structural differences, n-type and p-type devices were designed and simulated. The circuit simulation according to TID effects was conducted using Berkeley short-channel insulated-gate FET model (BSIM) common multi-gate (CMG) parameters. The NS-FET generated more VT shift than the NW-FET because the NS-FET had a wider gate oxide area and channel circumference, resulting in more interface hole traps. The abnormal VT shift leads to causing unstable circuit operation and delays. Therefore, it was confirmed that the ability of the NW-FET to tolerate TID effects was better than that of the NS-FET. Full article
(This article belongs to the Special Issue New CMOS Devices and Their Applications II)
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Article
Modelling Reliability Characteristics of Technical Equipment of Local Area Computer Networks
Electronics 2021, 10(8), 955; https://doi.org/10.3390/electronics10080955 - 16 Apr 2021
Cited by 1 | Viewed by 459
Abstract
Technical systems in the modern global world are rapidly evolving and improving. In most cases, these are large-scale multi-level systems and one of the problems that arises in the design process of such systems is to determine their reliability. Accordingly, in the paper, [...] Read more.
Technical systems in the modern global world are rapidly evolving and improving. In most cases, these are large-scale multi-level systems and one of the problems that arises in the design process of such systems is to determine their reliability. Accordingly, in the paper, a mathematical model based on the Weibull distribution has been developed for determining a computer network reliability. In order to simplify calculating the reliability characteristics, the system is considered to be a hierarchical one, ramified to level 2, with bypass through the level. The developed model allows us to define the following parameters: the probability distribution of the count of working output elements, the availability function of the system, the duration of the system’s stay in each of its working states, and the duration of the system’s stay in the prescribed availability condition. The accuracy of the developed model is high. It can be used to determine the reliability parameters of the large, hierarchical, ramified systems. The research results of modelling a local area computer network are presented. In particular, we obtained the following best option for connecting workstations: 4 of them are connected to the main hub, and the rest (16) are connected to the second level hub, with a time to failure of 4818 h. Full article
(This article belongs to the Section Computer Science & Engineering)
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