Next Issue
Volume 11, February-2
Previous Issue
Volume 11, January-2

Electronics, Volume 11, Issue 3 (February-1 2022) – 213 articles

Cover Story (view full-size image): Vacuum transistors, microscale vacuum triodes fabricated on a chip, have recently rekindled researchers’ interest because they can combine the respective advantages of traditional vacuum triodes and solid-state transistors. While most previous works have mainly focused on field emission vacuum transistors, a vacuum transistor based on field-assisted thermionic emission from a carbon nanotube is proposed here. The device exhibits an ON/OFF current ratio of 104 and a subthreshold slope of ~4 V/dec. Benefiting from the field-assisted thermionic emission mechanism, the electric field in the device is about one order of magnitude smaller than that in devices based on field emission, and the surface of the thermionic emitter shows much less gas molecule absorption than cold field emitters. These aspects are expected to be helpful for improving the stability and uniformity of the devices. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
Article
An Optimal Procedure for the Design of Discrete Constrained Lens Antennas with Minimized Optical Aberrations. Part II: Three-Dimensional Multifocal Architectures
Electronics 2022, 11(3), 503; https://doi.org/10.3390/electronics11030503 - 08 Feb 2022
Cited by 1 | Viewed by 371
Abstract
Novel three-dimensional discrete lens antennas characterized by a number of focal points ranging from one to five and defined explicitly via analytical equations are presented in the paper. A procedure to derive rotationally symmetric afocal lenses starting from multifocal lenses that are not [...] Read more.
Novel three-dimensional discrete lens antennas characterized by a number of focal points ranging from one to five and defined explicitly via analytical equations are presented in the paper. A procedure to derive rotationally symmetric afocal lenses starting from multifocal lenses that are not rotationally symmetric is proposed as well. In addition, an innovative method to identify the focal surface minimizing the optical aberrations is derived. The lenses are compared in terms of optical aberrations and accommodation constraints. The most suitable lens architectures depend mainly on the required angular field of view and magnification factor. It is shown that a reduction by a factor close to 3 in the optical aberrations can be obtained when selecting the most appropriate lens architecture and keeping comparable accommodation constraints. The results, derived exploiting a geometrical optics (GO) formulation, provide useful indications for the preliminary design of constrained lens antennas before adopting full wave rigorous techniques. Three-dimensional discrete lens antennas can offer significant advantages as compared to conventional analog beamforming networks (as those based on Butler matrixes) in terms of frequency bandwidth, number of beams and number of radiating elements. Full article
(This article belongs to the Special Issue High-Performance Antenna Design and Applications)
Show Figures

Figure 1

Article
Towards a Digital Twin of Coronary Stenting: A Suitable and Validated Image-Based Approach for Mimicking Patient-Specific Coronary Arteries
Electronics 2022, 11(3), 502; https://doi.org/10.3390/electronics11030502 - 08 Feb 2022
Viewed by 529
Abstract
Considering the field of application involving stent deployment simulations, the exploitation of a digital twin of coronary stenting that can reliably mimic the patient-specific clinical reality could lead to improvements in individual treatments. A starting step to pursue this goal is the development [...] Read more.
Considering the field of application involving stent deployment simulations, the exploitation of a digital twin of coronary stenting that can reliably mimic the patient-specific clinical reality could lead to improvements in individual treatments. A starting step to pursue this goal is the development of simple, but at the same time, robust and effective computational methods to obtain a good compromise between the accuracy of the description of physical phenomena and computational costs. Specifically, this work proposes an approach for the development of a patient-specific artery model to be used in stenting simulations. The finite element model was generated through a 3D reconstruction based on the clinical imaging (coronary Optical Coherence Tomography (OCT) and angiography) acquired on the pre-treatment patient. From a mechanical point of view, the coronary wall was described with a suitable phenomenological model, which is consistent with more complex constitutive approaches and accounts for the in vivo pressurization and axial pre-stretch. The effectiveness of this artery modeling method was tested by reproducing in silico the stenting procedures of two clinical cases and comparing the computational results with the in vivo lumen area of the stented vessel. Full article
(This article belongs to the Special Issue Digital Twin Technology: New Frontiers for Personalized Healthcare)
Show Figures

Graphical abstract

Article
A Novel Path Voting Algorithm for Surface Crack Detection
Electronics 2022, 11(3), 501; https://doi.org/10.3390/electronics11030501 - 08 Feb 2022
Viewed by 342
Abstract
Path voting is a widely used technique for line structure detection in images. Traditional path voting, based on minimal-path, is performed to track paths based on how seeds grow. The former requires to set a starting point and an end point. Thus, the [...] Read more.
Path voting is a widely used technique for line structure detection in images. Traditional path voting, based on minimal-path, is performed to track paths based on how seeds grow. The former requires to set a starting point and an end point. Thus, the performance of minimal-path path voting depends on the initialization. However, high-quality initialization often requires human interaction, which limits its applications in practice. In this paper, a fully automatic path voting method has been proposed and applied for crack detection. The proposed path voting is performed to segment images, which partitions an image patch along the potential crack path and integrates the path to form a crack probability map. After path voting, crack seeds are sampled and modeled into a graph, and the edge weights are assigned using an attraction field algorithm. Finally, cracks are extracted by using spanning tree and tree pruning algorithms. Experimental results demonstrate that the proposed path voting approach can effectively infer the cracks from 2D optic images and 3D depth images. Full article
(This article belongs to the Special Issue Multimodal Signal, Image and Video Analysis and Application)
Show Figures

Figure 1

Article
Watermarking Applications of Krawtchouk–Sobolev Type Orthogonal Moments
Electronics 2022, 11(3), 500; https://doi.org/10.3390/electronics11030500 - 08 Feb 2022
Viewed by 313
Abstract
In this contribution, we consider the sequence {Hn(x;q)}n0 of monic polynomials orthogonal with respect to a Sobolev-type inner product involving forward difference operators For the first time in the literature, we apply [...] Read more.
In this contribution, we consider the sequence {Hn(x;q)}n0 of monic polynomials orthogonal with respect to a Sobolev-type inner product involving forward difference operators For the first time in the literature, we apply the non-standard properties of {Hn(x;q)}n0 in a watermarking problem. Several differences are found in this watermarking application for the non-standard cases (when j>0) with respect to the standard classical Krawtchouk case λ=μ=0. Full article
(This article belongs to the Special Issue Recent Developments and Applications of Image Watermarking)
Show Figures

Figure 1

Article
An Omnidirectional Platform for Education and Research in Cooperative Robotics
Electronics 2022, 11(3), 499; https://doi.org/10.3390/electronics11030499 - 08 Feb 2022
Viewed by 340
Abstract
In this paper we present a new, affordable, omnidirectional robot platform which is suitable for research and education in cooperative robotics. We design and implement the platform for the purpose of multi-agent object manipulation and transportation. The design consists of three omnidirectional wheels [...] Read more.
In this paper we present a new, affordable, omnidirectional robot platform which is suitable for research and education in cooperative robotics. We design and implement the platform for the purpose of multi-agent object manipulation and transportation. The design consists of three omnidirectional wheels with two additional traction wheels, making multirobot object manipulation possible. It is validated by performing simple experiments using a setup with one robot and one target object. The execution flow of a simple task (Approach–Press–Lift–Hold–Set) is studied. In addition, we experiment to find the limits of the applied pressure and object orientation under certain conditions. The experiments demonstrate the significance of our inexpensive platform for research and education by proving its feasibility of use in topics such as collaborative robotics, physical interaction, and mobile manipulation. Full article
(This article belongs to the Special Issue Recent Advances in Educational Robotics)
Show Figures

Figure 1

Article
Design of a Broadband MMIC Driver Amplifier with Enhanced Feedback and Temperature Compensation Technique
Electronics 2022, 11(3), 498; https://doi.org/10.3390/electronics11030498 - 08 Feb 2022
Cited by 1 | Viewed by 362
Abstract
This paper presents a broadband GaN pseudo high-electron-mobility transistor (pHEMT) two-stage driver amplifier based on an enhanced feedback technique for a wideband system. Through well-designed parameter values of the feedback and the matching structure of the circuit, a relatively flat frequency response was [...] Read more.
This paper presents a broadband GaN pseudo high-electron-mobility transistor (pHEMT) two-stage driver amplifier based on an enhanced feedback technique for a wideband system. Through well-designed parameter values of the feedback and the matching structure of the circuit, a relatively flat frequency response was obtained over a wide frequency band. Simultaneously, in order to reduce the fluctuation of current caused by the environmental temperature, a bias circuit with quiescent current temperature compensation was designed. The driver power amplifier, which was implemented in the form of a monolithic microwave integrated circuit (MMIC), was designed to drive a broadband high-power amplifier. The designed broadband driver amplifier for the 6 GHz to 20 GHz frequency band had a very small die size of 1.5 × 1.2 mm2 due to the use of an optimized impedance matching structure. It exhibited a small-signal gain of 12.5 dB and output power of 26 dBm. The flatness of this driver amplifier for gain and output power was achieved as ±2.5 dB and ±1 dB over the entire frequency band, respectively. The experimental results showed up to 35 dBm in the OIP3, and the current variation range was ±5 mA after using the temperature compensation bias circuit. Full article
(This article belongs to the Section Microelectronics)
Show Figures

Figure 1

Article
Virtual Reality Tool for Exploration of Three-Dimensional Cellular Automata
Electronics 2022, 11(3), 497; https://doi.org/10.3390/electronics11030497 - 08 Feb 2022
Viewed by 437
Abstract
We present a Virtual Reality (VR) tool for exploration of three-dimensional cellular automata. In addition to the traditional visual representation offered by other implementations, this tool allows users to aurally render the active (alive) cells of an automaton in sequence along one axis [...] Read more.
We present a Virtual Reality (VR) tool for exploration of three-dimensional cellular automata. In addition to the traditional visual representation offered by other implementations, this tool allows users to aurally render the active (alive) cells of an automaton in sequence along one axis or simultaneously create melodic and harmonic textures, while preserving in all cases the relative locations of these cells to the user. The audio spatialization method created for this research can render the maximum number of audio sources specified by the underlying software (255) without audio dropouts. The accuracy of the achieved spatialization is unrivaled since it is based on actual distance measurements as opposed to coarse distance approximations used by other spatialization methods. A subjective evaluation (effectively, self-reported measurements) of our system (n=30) indicated no significant differences in user experience or intrinsic motivation between VR and traditional desktop versions (PC). However, participants in the PC group explored more of the universe than the VR group. This difference is likely to be caused by the familiarity of our cohort with PC-based games. Full article
(This article belongs to the Special Issue Virtual Reality and Scientific Visualization)
Show Figures

Figure 1

Review
Bringing Emotion Recognition Out of the Lab into Real Life: Recent Advances in Sensors and Machine Learning
Electronics 2022, 11(3), 496; https://doi.org/10.3390/electronics11030496 - 08 Feb 2022
Viewed by 584
Abstract
Bringing emotion recognition (ER) out of the controlled laboratory setup into everyday life can enable applications targeted at a broader population, e.g., helping people with psychological disorders, assisting kids with autism, monitoring the elderly, and general improvement of well-being. This work reviews progress [...] Read more.
Bringing emotion recognition (ER) out of the controlled laboratory setup into everyday life can enable applications targeted at a broader population, e.g., helping people with psychological disorders, assisting kids with autism, monitoring the elderly, and general improvement of well-being. This work reviews progress in sensors and machine learning methods and techniques that have made it possible to move ER from the lab to the field in recent years. In particular, the commercially available sensors collecting physiological data, signal processing techniques, and deep learning architectures used to predict emotions are discussed. A survey on existing systems for recognizing emotions in real-life scenarios—their possibilities, limitations, and identified problems—is also provided. The review is concluded with a debate on what challenges need to be overcome in the domain in the near future. Full article
(This article belongs to the Special Issue Machine Learning in Electronic and Biomedical Engineering)
Show Figures

Figure 1

Article
A Novel Deep Learning Model for Detection of Severity Level of the Disease in Citrus Fruits
Electronics 2022, 11(3), 495; https://doi.org/10.3390/electronics11030495 - 08 Feb 2022
Viewed by 618
Abstract
Citrus fruit diseases have an egregious impact on both the quality and quantity of the citrus fruit production and market. Automatic detection of severity is essential for the high-quality production of fruit. In the current work, a citrus fruit dataset is preprocessed by [...] Read more.
Citrus fruit diseases have an egregious impact on both the quality and quantity of the citrus fruit production and market. Automatic detection of severity is essential for the high-quality production of fruit. In the current work, a citrus fruit dataset is preprocessed by rescaling and establishing bounding boxes with labeled image software. Then, a selective search, which combines the capabilities of both an extensive search and graph-based segmentation, is applied. The proposed deep neural network (DNN) model is trained to detect targeted areas of the disease with its severity level using citrus fruits that have been labeled with the help of a domain expert with four severity levels (high, medium, low and healthy) as ground truth. Transfer learning using VGGNet is applied to implement a multi-classification framework for each class of severity. The model predicts the low severity level with 99% accuracy, and the high severity level with 98% accuracy. The model demonstrates 96% accuracy in detecting healthy conditions and 97% accuracy in detecting medium severity levels. The result of the work shows that the proposed approach is valid, and it is efficient for detecting citrus fruit disease at four levels of severity. Full article
Show Figures

Figure 1

Article
Threat Analysis and Distributed Denial of Service (DDoS) Attack Recognition in the Internet of Things (IoT)
Electronics 2022, 11(3), 494; https://doi.org/10.3390/electronics11030494 - 08 Feb 2022
Cited by 1 | Viewed by 580
Abstract
The Internet of Things (IoT) plays a crucial role in various sectors such as automobiles and the logistic tracking medical field because it consists of distributed nodes, servers, and software for effective communication. Although this IoT paradigm has suffered from intrusion threats and [...] Read more.
The Internet of Things (IoT) plays a crucial role in various sectors such as automobiles and the logistic tracking medical field because it consists of distributed nodes, servers, and software for effective communication. Although this IoT paradigm has suffered from intrusion threats and attacks that cause security and privacy issues, existing intrusion detection techniques fail to maintain reliability against the attacks. Therefore, the IoT intrusion threat has been analyzed using the sparse convolute network to contest the threats and attacks. The web is trained using sets of intrusion data, characteristics, and suspicious activities, which helps identify and track the attacks, mainly, Distributed Denial of Service (DDoS) attacks. Along with this, the network is optimized using evolutionary techniques that identify and detect the regular, error, and intrusion attempts under different conditions. The sparse network forms the complex hypotheses evaluated using neurons, and the obtained event stream outputs are propagated to further hidden layer processes. This process minimizes the intrusion involvement in IoT data transmission. Effective utilization of training patterns in the network successfully classifies the standard and threat patterns. Then, the effectiveness of the system is evaluated using experimental results and discussion. Network intrusion detection systems are superior to other types of traditional network defense in providing network security. The research applied an IGA-BP network to combat the growing challenge of Internet security in the big data era, using an autoencoder network model and an improved genetic algorithm to detect intrusions. MATLAB built it, which ensures a 98.98% detection rate and 99.29% accuracy with minimal processing complexity, and the performance ratio is 90.26%. A meta-heuristic optimizer was used in the future to increase the system’s ability to forecast attacks. Full article
(This article belongs to the Special Issue Intelligence/Security Embedded IoT Systems)
Show Figures

Figure 1

Article
An Optimal Procedure for the Design of Discrete Constrained Lens Antennas with Minimized Optical Aberrations. Part I: Two-Dimensional Architectures
Electronics 2022, 11(3), 493; https://doi.org/10.3390/electronics11030493 - 08 Feb 2022
Viewed by 317
Abstract
Despite to the significant literature available on the design and applications of two-dimensional constrained lens antennas, and in particular on the Rotman–Turner lens, a rigorous study focused on the minimization of optical aberrations does not seem to be available. A general procedure for [...] Read more.
Despite to the significant literature available on the design and applications of two-dimensional constrained lens antennas, and in particular on the Rotman–Turner lens, a rigorous study focused on the minimization of optical aberrations does not seem to be available. A general procedure for the design of two-dimensional bootlace lens antennas with a flat front profile is proposed in this paper. For the 3-foci lens, the best performance is achievable when, in addition to the three nominal focal points, two additional symmetric quasi foci are present. For the 4-foci lens the best performance is obtained when the presence of one additional quasi focus on the lens axis is guaranteed. Both the 3- and 4-foci lenses, when optimized, converge to the same configuration which exhibits aberrations following a Chebyshev-like behavior and guarantees quasi 5 foci. The optimized lens architecture is such that, for every scanning angle, the aberrations in the two extreme points are the most significant and exhibit opposite values. Any variation from this optimal condition implies increased aberrations. Although a 5-foci lens with flat front profile cannot be derived, one quasi-5-foci lens is derived asymptotically starting from two completely different lens architectures. A maximization of the number of foci combined with a rigorous derivation of the focal curve turned to be the key driver to identify an optimal two-dimensional bootlace lens. The quasi 5-foci lens presented can be considered the optimum Rotman–Turner lens in terms of optical aberrations allowing to reduce the optical aberrations by about one order of magnitude as compared to the best results available in the literature. Full article
(This article belongs to the Special Issue High-Performance Antenna Design and Applications)
Show Figures

Figure 1

Article
A Comprehensive Virtual Synchronous Generator Control Strategy for Harmonic and Imbalance Voltage Suppression of Multi-Inverter Parallel Microgrid
Electronics 2022, 11(3), 492; https://doi.org/10.3390/electronics11030492 - 08 Feb 2022
Viewed by 299
Abstract
To reduce the impact of the imbalance of mixed non-linear loads on an inverter voltage output in the microgrid, we improve the disadvantage of the lack of damping and inertia for traditional droop control. This paper proposes a comprehensive virtual synchronous generator (VSG) [...] Read more.
To reduce the impact of the imbalance of mixed non-linear loads on an inverter voltage output in the microgrid, we improve the disadvantage of the lack of damping and inertia for traditional droop control. This paper proposes a comprehensive virtual synchronous generator (VSG) control strategy for harmonic suppression and imbalance suppression of a multi-inverter parallel microgrid. On one hand, an improved VSG control strategy is proposed to increase the damping and inertia of distributed generations (DGs) in the microgrid, and secondary control is introduced to improve system stability. On the other hand, the frequency division suppression control strategy is used to eliminate the influence of harmonics, and the negative sequence component is compensated to eliminate the influence of imbalance. Then small-signal analysis is used for analysis of the stability of the strategy. Finally, we verify the comprehensive control strategy proposed in this paper through experiments. The experimental results suggest a significant improvement on the voltage, frequency, power optimization, handling of non-linear load and capacity distribution precision, as well as providing inertia support for the system. Full article
(This article belongs to the Special Issue Control of Nonlinear Systems and Industrial Processes)
Show Figures

Figure 1

Article
Solar Energy Compensation for Building Energy Saving with Thermal Comfort in a Cold Climate
Electronics 2022, 11(3), 491; https://doi.org/10.3390/electronics11030491 - 08 Feb 2022
Viewed by 333
Abstract
This paper proposes an energy-saving strategy with assistance from solar thermal compensation for building energy systems. The target of the control strategy was to minimize energy consumption under thermal comfort constraints in buildings. First, the factors influential to indoor temperature in building environments [...] Read more.
This paper proposes an energy-saving strategy with assistance from solar thermal compensation for building energy systems. The target of the control strategy was to minimize energy consumption under thermal comfort constraints in buildings. First, the factors influential to indoor temperature in building environments were analyzed. Secondly, the internal and external factors, such as building materials; building orientation; window size; heating, ventilation, and air conditioning (HVAC) facilities; blinding device; solar irradiation; wind speed; and outdoor temperature were used to construct a building model on the platform ENERGYPLUS (E+). A controller aiming to regulate the amount of solar irradiation was developed with the Building Controls Virtual Test Bed (BCVTB) tool. Afterward, the building performance under different strategies was tested by co-simulation using both the computational platforms, E+ and BCVTB. The optimum scheme achieved 30.6% energy savings while meeting the same comfort criterion of its competition strategy. The study verified that the proposed strategy of combined heating, ventilation, and air conditioning and blind control could realize the energy savings and comfort satisfaction at the same time. The proposed method provides a reference to the development of low-/zero-energy building concepts in the field. Full article
(This article belongs to the Special Issue Advancement in Smart Building Technologies)
Show Figures

Figure 1

Article
An Energy-Saving Scheduling Algorithm for Multipath TCP in Wireless Networks
Electronics 2022, 11(3), 490; https://doi.org/10.3390/electronics11030490 - 08 Feb 2022
Viewed by 358
Abstract
Multipath TCP (MPTCP) allows the system to use available paths through multiple network interfaces. This aggregation of bandwidth increases the throughput of the network but also consumes more energy to maintain connections between multiple interfaces. Existing algorithms tend to shift traffic from the [...] Read more.
Multipath TCP (MPTCP) allows the system to use available paths through multiple network interfaces. This aggregation of bandwidth increases the throughput of the network but also consumes more energy to maintain connections between multiple interfaces. Existing algorithms tend to shift traffic from the high energy path to the low energy path to save energy. However, when the performance of the less energy-intensive path deteriorates, continued use of that path will reduce throughput. To alleviate this issue and reduce energy consumption while ensuring network throughput, this paper proposes an energy-saving scheduling system named ES-MPTCP, which can be combined with the path management module to manage subflows, thereby determining the priority of subflows and which subflows to be used for data transmission. The ES-MPTCP algorithm designs a target optimization function based on path throughput and energy consumption to find different sets of suitable subflows for different applications to reduce energy consumption and guarantee throughput. The extensive experimental results based on the Linux real platform demonstrate that the ES-MPTCP algorithm has the best performance, which can improve throughput by 13.6%, reduce energy consumption by 16.2% and increase the energy efficiency up to 23%. Full article
(This article belongs to the Special Issue Data Analysis in Intelligent Communication Systems (ICS))
Show Figures

Figure 1

Article
Effect of Phase Noise on the Optical Millimeter-Wave Signal in the DWDM-RoF System
Electronics 2022, 11(3), 489; https://doi.org/10.3390/electronics11030489 - 08 Feb 2022
Viewed by 322
Abstract
In this study, we examined the effect of phase noise on the optical millimeter-wave (mm-wave) signal in a dense wavelength division multiplexing radio-over-fiber (DWDM-RoF) system. A single modulator was used to generate the optical mm-wave signal in the DWDM-RoF system. This paper addresses [...] Read more.
In this study, we examined the effect of phase noise on the optical millimeter-wave (mm-wave) signal in a dense wavelength division multiplexing radio-over-fiber (DWDM-RoF) system. A single modulator was used to generate the optical mm-wave signal in the DWDM-RoF system. This paper addresses the impact of phase noise, which results from phase imbalance, on the optical mm-wave signal. To lower the effect of phase noise on the optical mm-wave signal, the phase imbalance should be controlled. The phase imbalance can be controlled and decreased by adjusting the phase at the phase shift (PS). The system performance was analyzed using various parameters such as bit error rate (BER), signal-to-noise ratio (SNR), optical signal to noise ratio (OSNR), and error vector magnitude (EVM). From the results, we found the phase imbalance affected the optical mm-wave signal due to the imbalanced splitting of the signal intensity at the MZM. The phase imbalance impacts the phase noise, which impacts the optical mm-wave signal. The phase noise could be decreased by controlling the phase imbalance at the phase of 5π/12. The best results at the phase of 5π/12 were collected for phase noise at 0.02 degrees. Full article
(This article belongs to the Special Issue Advances in Millimeter-Wave Cellular Networks)
Show Figures

Graphical abstract

Article
BAIV: An Efficient Blockchain-Based Anonymous Authentication and Integrity Preservation Scheme for Secure Communication in VANETs
Electronics 2022, 11(3), 488; https://doi.org/10.3390/electronics11030488 - 08 Feb 2022
Cited by 1 | Viewed by 508
Abstract
Recent development in intelligent transport systems (ITS) has led to the improvement of driving experience in vehicular ad-hoc network (VANET) systems. Providing a low computational cost with high serving capability, however, is a critical phenomenon in the current VANET system. In the existing [...] Read more.
Recent development in intelligent transport systems (ITS) has led to the improvement of driving experience in vehicular ad-hoc network (VANET) systems. Providing a low computational cost with high serving capability, however, is a critical phenomenon in the current VANET system. In the existing scenario, when the authenticated vehicle user moves from one roadside unit (RSU) to another RSU region, re-authentication of the vehicle user is required by the current RSU, which increases the computational complexity. To overcome the above-mentioned challenge, a blockchain-based authentication protocol is developed in this work. In this suggested process, blockchain is integrated with VANET, which enables the authentication of the vehicle user without the involvement of a trusted authority. Moreover, the integrity of the message and privacy of vehicle users are preserved in the blockchain network. Even though many blockchain-based schemes have been proposed recently, the existing schemes were not focused on conditional anonymity. However, in our proposed scheme, conditional privacy is introduced to revoke the malicious vehicles in the case of disputes and to avoid further damage to the VANET system. As a result, the proposed scheme provides an efficient mechanism for anonymous authentication, privacy, and integrity preservation with conditional tracking. Finally, the defense against different security threats is explained in the security analysis section, and the performance investigation section shows the competence and efficacy of our method with similar related methods. Full article
(This article belongs to the Special Issue Blockchain Based Electronic Healthcare Solution and Security)
Show Figures

Figure 1

Article
Ultrawideband Cross-Polarization Converter Using Anisotropic Reflective Metasurface
Electronics 2022, 11(3), 487; https://doi.org/10.3390/electronics11030487 - 08 Feb 2022
Cited by 1 | Viewed by 478
Abstract
Broadband metasurface-based devices are essential and indispensable in modern wireless communication systems. This paper presents an ultra−wideband and wide incident angle reflective cross−polarization converter metasurface. The unit cell of the proposed structure is a 45° rotated anisotropic meta−sheet developed by cutting the rhombus−shaped [...] Read more.
Broadband metasurface-based devices are essential and indispensable in modern wireless communication systems. This paper presents an ultra−wideband and wide incident angle reflective cross−polarization converter metasurface. The unit cell of the proposed structure is a 45° rotated anisotropic meta−sheet developed by cutting the rhombus−shaped patch from the central part of the square patch. The unit cell’s top structure and ground blocking sheet are made of copper, whereas a dielectric substrate (FR−4) is used as an intermediate spacer between them. The unit cell thickness is minimal compared to the operating wavelength (1/14λ, where λ is the wavelength of the starting frequency of 13 GHz of the operating band). The proposed structure efficiently converts linearly polarized waves into their orthogonal component, with a polarization conversion ratio of (PCR > 90%) over a broad frequency spectrum of 13 GHz to 26 GHz. The physical origin of polarization conversion is also depicted using surface current distribution plots. An ultra−wideband and highly efficient polarization conversion (above 90%) is achieved with the help of strong electromagnetic resonance coupling between the upper and lower layer of the metasurface. This kind of ultra−wideband polarization conversion metasurface can be employed in satellite communication, radar cross−section reduction, and navigation systems. Full article
Show Figures

Figure 1

Article
A Novel Android Botnet Detection System Using Image-Based and Manifest File Features
Electronics 2022, 11(3), 486; https://doi.org/10.3390/electronics11030486 - 08 Feb 2022
Viewed by 562
Abstract
Malicious botnet applications have become a serious threat and are increasingly incorporating sophisticated detection avoidance techniques. Hence, there is a need for more effective mitigation approaches to combat the rise of Android botnets. Although the use of Machine Learning to detect botnets has [...] Read more.
Malicious botnet applications have become a serious threat and are increasingly incorporating sophisticated detection avoidance techniques. Hence, there is a need for more effective mitigation approaches to combat the rise of Android botnets. Although the use of Machine Learning to detect botnets has been a focus of recent research efforts, several challenges remain. To overcome the limitations of using hand-crafted features for Machine-Learning-based detection, in this paper, we propose a novel mobile botnet detection system based on features extracted from images and a manifest file. The scheme employs a Histogram of Oriented Gradients and byte histograms obtained from images representing the app executable and combines these with features derived from the manifest files. Feature selection is then applied to utilize the best features for classification with Machine-Learning algorithms. The proposed system was evaluated using the ISCX botnet dataset, and the experimental results demonstrate its effectiveness with F1 scores ranging from 0.923 to 0.96 using popular Machine-Learning algorithms. Furthermore, with the Extra Trees model, up to 97.5% overall accuracy was obtained using an 80:20 train–test split, and 96% overall accuracy was obtained using 10-fold cross validation. Full article
(This article belongs to the Special Issue High Accuracy Detection of Mobile Malware Using Machine Learning)
Show Figures

Figure 1

Article
Mobile Broadband Performance Evaluation: Analysis of National Reports
Electronics 2022, 11(3), 485; https://doi.org/10.3390/electronics11030485 - 08 Feb 2022
Viewed by 365
Abstract
Five decades have passed since the first bit was transmitted over the internet. Although the internet has improved our lives and led to the digital economy, currently only 51% of the world’s population have access to it. Currently, consumers mostly access the internet [...] Read more.
Five decades have passed since the first bit was transmitted over the internet. Although the internet has improved our lives and led to the digital economy, currently only 51% of the world’s population have access to it. Currently, consumers mostly access the internet via mobile broadband, 2G, 3G, and 4G services. Regulatory bodies such as the Federal Communications Commission (FCC) of the US are responsible for ensuring that consumers receive an adequate service from Mobile Network Operators (MNOs). Usually, regulators evaluate the performance of each MNO in terms of service quality yearly and publish a report. To evaluate performance, metrics such as coverage, download/upload speed, and the number of subscribers can be used. However, the evaluation process and the metrics used by each regulatory body are inconsistent, and this makes it hard to determine which nations are providing adequate services to their citizens. Furthermore, it is not clear as to which performance evaluation is the right path. In this case study, we analyzed the reports released from eight nations (United States of America, United Kingdom, France, South Korea, Japan, Singapore, and Australia) as of the year 2020. We then point out the advantages and the drawbacks of the current evaluation process and metrics. Furthermore, a discussion on why the current methods are not sufficient to evaluate 5G services is presented. Our findings indicate that there is a great need for a unified metric and that this process becomes more complex with the rollout of 5G. Full article
(This article belongs to the Special Issue Wireless Network Protocols and Performance Evaluation, Volume II)
Show Figures

Figure 1

Article
Driver Cardiovascular Disease Detection Using Seismocardiogram
Electronics 2022, 11(3), 484; https://doi.org/10.3390/electronics11030484 - 07 Feb 2022
Viewed by 416
Abstract
This article deals with the treatment and application of cardiac biosignals, an excited accelerometer, and a gyroscope in the prevention of accidents on the road. Previously conducted studies say that the seismocardiogram is a measure of cardiac microvibration signals that allows for detecting [...] Read more.
This article deals with the treatment and application of cardiac biosignals, an excited accelerometer, and a gyroscope in the prevention of accidents on the road. Previously conducted studies say that the seismocardiogram is a measure of cardiac microvibration signals that allows for detecting rhythms, heart valve opening and closing disorders, and monitoring of patients’ breathing. This article refers to the seismocardiogram hypothesis that the measurements of a seismocardiogram could be used to identify drivers’ heart problems before they reach a critical condition and safely stop the vehicle by informing the relevant departments in a nonclinical manner. The proposed system works without an electrocardiogram, which helps to detect heart rhythms more easily. The estimation of the heart rate (HR) is calculated through automatically detected aortic valve opening (AO) peaks. The system is composed of two micro-electromechanical systems (MEMSs) to evaluate physiological parameters and eliminate the effects of external interference on the entire system. The few digital filtering methods are discussed and benchmarked to increase seismocardiogram efficiency. As a result, the fourth adaptive filter obtains the estimated HR = 65 beats per min (bmp) in a still noisy signal (SNR = −11.32 dB). In contrast with the low processing benefit (3.39 dB), 27 AO peaks were detected with a 917.56-ms peak interval mean over 1.11 s, and the calculated root mean square error (RMSE) was 0.1942 m/s2 when the adaptive filter order is 50 and the adaptation step is equal to 0.933. Full article
Show Figures

Figure 1

Article
A Non-Isolated Hybrid Zeta Converter with a High Voltage Gain and Reduced Size of Components
Electronics 2022, 11(3), 483; https://doi.org/10.3390/electronics11030483 - 07 Feb 2022
Viewed by 341
Abstract
In this paper a novel non-coupled inductor-based hybrid Zeta converter with a minimal duty cycle is proposed. The converter’s potential benefits include buck and boost operation modes, easy implementation, continuous input current, and high efficiency. The converter provides a higher voltage gain than [...] Read more.
In this paper a novel non-coupled inductor-based hybrid Zeta converter with a minimal duty cycle is proposed. The converter’s potential benefits include buck and boost operation modes, easy implementation, continuous input current, and high efficiency. The converter provides a higher voltage gain than a conventional Zeta converter and is adapted to EV and LED applications due to the continuous input current. The proposed converter operates in three distinct operation modes via two electronic switches, each operated independently with a different duty ratio. This paper also analyzes the converter’s performance based on equivalent circuits, and analytical waveforms in each operating mode and design procedure are shown. The voltage gain and dynamic modelling are computed for both buck and boost operational modes for the hybrid Zeta converter. The efficiency and performance of the converter in both operating modes are validated using MATLAB/Simulink. Hardware in the loop (HIL) testing method on RT-LAB OP-5700 for both operation modes of the converter are performed. The peak efficiency of the proposed converter with an input voltage of 36 V is obtained at 95.2%. The proposed converter offers a wide voltage gain at a small duty cycle with fewer components and high efficiency. Simulations and experiments have been carried out under different conditions and the results proved that the proposed converter is a viable solution. Full article
Show Figures

Figure 1

Article
Digital Pole Control for Speed and Torque Variation in an Axial Flux Motor with Permanent Magnets
Electronics 2022, 11(3), 482; https://doi.org/10.3390/electronics11030482 - 07 Feb 2022
Viewed by 376
Abstract
The use of renewable energies in the transportation industry has prompted the development of higher power electric motors and intelligent electronic traction systems. However, the typical coupling between the two continues to be mechanical, which reduces its efficiency and useful life. On the [...] Read more.
The use of renewable energies in the transportation industry has prompted the development of higher power electric motors and intelligent electronic traction systems. However, the typical coupling between the two continues to be mechanical, which reduces its efficiency and useful life. On the other hand, permanent magnet axial flux motor configurations make it possible to dispense with mechanical couplings, due to their high torque at low speeds due to their direct application on the wheels of vehicles. In this work, the design of a digital pole commutation system is presented, applied to an axial flux motor with permanent magnets for speed and torque control at a constant speed. The performance of the system is evaluated with experimental measurements; proving the effectiveness of the design, obtaining torques of up to 1784 Nm without extra mechanical couplings and maximum speed regulation errors of 8.43%. Full article
(This article belongs to the Section Electrical and Autonomous Vehicles)
Show Figures

Figure 1

Article
Content-Addressable Memory System Using a Nanoelectromechanical Memory Switch
Electronics 2022, 11(3), 481; https://doi.org/10.3390/electronics11030481 - 07 Feb 2022
Viewed by 297
Abstract
Content-addressable memory (CAM) performs a parallel search operation by comparing the search data with all content stored in memory during a single cycle, instead of finding the data using an address. Conventional CAM designs use a dynamic CMOS architecture for high matching speed [...] Read more.
Content-addressable memory (CAM) performs a parallel search operation by comparing the search data with all content stored in memory during a single cycle, instead of finding the data using an address. Conventional CAM designs use a dynamic CMOS architecture for high matching speed and high density; however, such implementations require the use of system clocks, and thus, suffer from timing violations and design limitations, such as charge sharing. In this paper, we propose a static-based architecture for a low-power, high-speed binary CAM (BCAM) and ternary CAM (TCAM), using a nanoelectromechanical (NEM) memory switch for nonvolatile data storage. We designed the proposed CAM architectures on a 65 nm process node with a 1.2 V operating voltage. The results of the layout simulation show that the proposed design has up to 23% less propagation delay, three times less matching power, and 9.4 times less area than a conventional design. Full article
(This article belongs to the Special Issue Mixed Signal Circuit Design)
Show Figures

Figure 1

Article
Demystifying Non-Isolated DC–DC Topologies on Partial Power Processing Architectures
Electronics 2022, 11(3), 480; https://doi.org/10.3390/electronics11030480 - 06 Feb 2022
Viewed by 498
Abstract
This paper discusses the possibility of achieving partial power processing with non-isolated DC–DC topologies. To this end, partial power converter architectures are seen as an interesting solution for reducing the power processed by the converter. We observed via simulations that single-inductor non-isolated topologies [...] Read more.
This paper discusses the possibility of achieving partial power processing with non-isolated DC–DC topologies. To this end, partial power converter architectures are seen as an interesting solution for reducing the power processed by the converter. We observed via simulations that single-inductor non-isolated topologies cannot achieve partial power processing since the obtained current and voltage waveforms were the same as those found in a full-power converter. However, when using double inductor non-isolated topologies, reduced current and improved efficiencies were achieved. In order to confirm the results obtained from the simulations, single- and double-inductor topologies were tested experimentally. Finally, it was concluded that a double-inductor non-isolated topology can improve its performance by using partial power processing. Full article
Show Figures

Figure 1

Article
Effect of Dielectric Thickness on Resistive Switching Polarity in TiN/Ti/HfO2/Pt Stacks
Electronics 2022, 11(3), 479; https://doi.org/10.3390/electronics11030479 - 06 Feb 2022
Viewed by 360
Abstract
In recent years, several materials and metal-insulator-metal devices are being intensively studied as prospective non-volatile memories due to their resistive switching effect. In this work, thickness-dependent resistive switching polarity was observed in TiN/Ti/HfO2/Pt structures as the sign of the voltages at [...] Read more.
In recent years, several materials and metal-insulator-metal devices are being intensively studied as prospective non-volatile memories due to their resistive switching effect. In this work, thickness-dependent resistive switching polarity was observed in TiN/Ti/HfO2/Pt structures as the sign of the voltages at which SET and RESET occur depended on the film thickness. A thorough revision of the previous literature on bipolar resistive switching polarity changes is made in order to condense previous knowledge of the subject in a brief and comprehensible way and explain the experimental measurements. The different resistive switching polarities occur in a similar voltage range, which is a new finding when compared to precedent research on the subject. A hypothesis is proposed to explain the change in resistive switching polarity, based on the assumption that polarity change is due to filament disruption occurring at different interfaces. Full article
(This article belongs to the Special Issue Resistive Memory Characterization, Simulation, and Compact Modeling)
Show Figures

Figure 1

Article
Features and Always-On Wake-Up Detectors for Sparse Acoustic Event Detection
Electronics 2022, 11(3), 478; https://doi.org/10.3390/electronics11030478 - 06 Feb 2022
Cited by 1 | Viewed by 420
Abstract
The need to understand and manage our surroundings has led to increased interest in sensor networks for the continuous monitoring of events and processes of interest. To reduce the power consumption required for continuous monitoring, dedicated always-on wake-up detectors have been designed, with [...] Read more.
The need to understand and manage our surroundings has led to increased interest in sensor networks for the continuous monitoring of events and processes of interest. To reduce the power consumption required for continuous monitoring, dedicated always-on wake-up detectors have been designed, with an emphasis on their low power consumption, simple and robust design, and reliable and accurate detection. An especially interesting application of these wake-up detectors is in detecting acoustic signals. In this paper, we present a study on the features and detectors applicable for the detection of sporadic acoustic events. We perform a state-of-the-art acoustic detector analysis, grouping the detectors based on the features they utilize and their implementations. This analysis shows that acoustic wake-up detectors predominantly utilize spectro-temporal (56%) and temporal features (36%). Following the state-of-the-art analysis, we select two detector architecture candidates for a case study on passing motor vehicle detection. We utilize our previously developed spectro-temporal decomposition detector and develop a novel level-crossing rate detector. The results of the case study shows that the proposed level-crossing rate detector has lower component count (44 compared to 70) and power consumption (9.1 µW compared to 34.6 µW) and is an optimal solution for SNRs over 0 dB. Full article
(This article belongs to the Special Issue Smart Sensing, Monitoring, and Control in Industry 4.0)
Show Figures

Figure 1

Article
Data Preprocessing Combination to Improve the Performance of Quality Classification in the Manufacturing Process
Electronics 2022, 11(3), 477; https://doi.org/10.3390/electronics11030477 - 06 Feb 2022
Viewed by 374
Abstract
The recent introduction of smart manufacturing, also called the ‘smart factory’, has made it possible to collect a significant number of multi-variate data from Internet of Things devices or sensors. Quality control using these data in the manufacturing process can play a major [...] Read more.
The recent introduction of smart manufacturing, also called the ‘smart factory’, has made it possible to collect a significant number of multi-variate data from Internet of Things devices or sensors. Quality control using these data in the manufacturing process can play a major role in preventing unexpected time and economic losses. However, the extraction of information about the manufacturing process is limited when there are missing values in the data and a data imbalance set. In this study, we improve the quality classification performance by solving the problem of missing values and data imbalances that can occur in the manufacturing process. This study proceeds with data cleansing, data substitution, data scaling, a data balancing model methodology, and evaluation. Five data balancing methods and a generative adversarial network (GAN) were used to proceed with data imbalance processing. The proposed schemes achieved an F1 score that was 0.5 higher than the F1 score of previous studies that used the same data. The data preprocessing combination proposed in this study is intended to be used to solve the problem of missing values and imbalances that occur in the manufacturing process. Full article
(This article belongs to the Special Issue Advances in Intelligent Systems and Networks)
Show Figures

Figure 1

Article
Bin-Picking Solution for Randomly Placed Automotive Connectors Based on Machine Learning Techniques
Electronics 2022, 11(3), 476; https://doi.org/10.3390/electronics11030476 - 06 Feb 2022
Viewed by 429
Abstract
This paper presents the development of a bin-picking solution based on low-cost vision systems for the manipulation of automotive electrical connectors using machine learning techniques. The automotive sector has always been in a state of constant growth and change, which also implies constant [...] Read more.
This paper presents the development of a bin-picking solution based on low-cost vision systems for the manipulation of automotive electrical connectors using machine learning techniques. The automotive sector has always been in a state of constant growth and change, which also implies constant challenges in the wire harnesses sector, and the emerging growth of electric cars is proof of this and represents a challenge for the industry. Traditionally, this sector is based on strong human work manufacturing and the need arises to make the digital transition, supported in the context of Industry 4.0, allowing the automation of processes and freeing operators for other activities with more added value. Depending on the car model and its feature packs, a connector can interface with a different number of wires, but the connector holes are the same. Holes not connected with wires need to be sealed, mainly to guarantee the tightness of the cable. Seals are inserted manually or, more recently, through robotic stations. Due to the huge variety of references and connector configurations, layout errors sometimes occur during seal insertion due to changed references or problems with the seal insertion machine. Consequently, faulty connectors are dumped into boxes, piling up different types of references. These connectors are not trash and need to be reused. This article proposes a bin-picking solution for classification, selection and separation, using a two-finger gripper, of these connectors for reuse in a new operation of removal and insertion of seals. Connectors are identified through a 3D vision system, consisting of an Intel RealSense camera for object depth information and the YOLOv5 algorithm for object classification. The advantage of this approach over other solutions is the ability to accurately detect and grasp small objects through a low-cost 3D camera even when the image resolution is low, benefiting from the power of machine learning algorithms. Full article
Show Figures

Figure 1

Article
An Optimization Framework for the Design of High-Speed PCB VIAs
Electronics 2022, 11(3), 475; https://doi.org/10.3390/electronics11030475 - 06 Feb 2022
Viewed by 569
Abstract
Signal integrity represents a key issue in all modern electronic systems, which are strongly dominated by the extreme component density usually employed on PCBs and the associated increase in the interconnection density. The use of multi-layer structures with microstrips connected by various types [...] Read more.
Signal integrity represents a key issue in all modern electronic systems, which are strongly dominated by the extreme component density usually employed on PCBs and the associated increase in the interconnection density. The use of multi-layer structures with microstrips connected by various types of Vertical Interconnect Accesses (VIAs) calls for design strategies that reduce the impedance mismatch and signal attenuation. The paper proposes a thorough analysis of the effects associated with the VIA geometry and presents a parametric evaluation of them. The obtained results represent the starting point for a possible design procedure that manages the geometric aspects of differential VIAs, aiming to optimize their electrical performance while reducing their occupation of PCB area. The optimization technique considers a differential VIA as a four-port circuit whose characteristics are evaluated with suitable Figures of Merit (FoMs), thus striving for an optimal design obtained with closed-loop iterations. The analysis is performed in both the time (TDR: Time-Domain Reflectometry) and frequency domains (S and Z parameters), thus allowing a dramatic reduction in the number of cases to be analyzed. The procedure is thoroughly described and validated using simulation results. Full article
(This article belongs to the Section Circuit and Signal Processing)
Show Figures

Figure 1

Article
Energy Efficiency and Throughput Maximization Using Millimeter Waves–Microwaves HetNets
Electronics 2022, 11(3), 474; https://doi.org/10.3390/electronics11030474 - 06 Feb 2022
Cited by 2 | Viewed by 385
Abstract
The deployment of millimeter waves can fulfil the stringent requirements of high bandwidth and high energy efficiency in fifth generation (5G) networks. Still, millimeter waves communication is challenging because it requires line of sight (LOS). The heterogeneous network (HetNet) of millimeter waves and [...] Read more.
The deployment of millimeter waves can fulfil the stringent requirements of high bandwidth and high energy efficiency in fifth generation (5G) networks. Still, millimeter waves communication is challenging because it requires line of sight (LOS). The heterogeneous network (HetNet) of millimeter waves and microwaves solves this problem. This paper proposes a millimeter -microwaves heterogeneous HetNet deployed in an indoor factory (InF). In InF, the manufacturing and production are performed inside big and small halls. We consider non standalone dual-mode base stations (DMBS) working on millimeter waves and microwaves. We analyze the network in terms of throughput and energy efficiency (EE). We formulate mixed-integer-non-linear-programming (MINLP) to maximize the throughput and EE of the network. The formulated problem is a complex optimization problem and hard to solve with exhaustive search. We propose a novel outer approximation algorithm (OAA) to solve this problem, and the proposed algorithm OAA achieves optimal solution at β = 10−3. At this β, the average throughput value obtained is approximately 50 Mbps, whereas the value of EE is 4.4 Mbits/J. We also compare the performance of OAA with the mesh-adaptive-direct-search-algorithm (NOMAD), and the experimental results verify that OAA outperforms NOMAD in terms of throughput and EE maximization. We also compare the performance of OAA with particle swarm optimization (PSO), genetic algorithm (GA), and many others optimization algorithms. Experimental results verify that OAA outperforms all other algorithms. Full article
Show Figures

Figure 1

Previous Issue
Back to TopTop