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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
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23 pages, 7157 KiB  
Article
An Optimal Procedure for the Design of Discrete Constrained Lens Antennas with Minimized Optical Aberrations. Part II: Three-Dimensional Multifocal Architectures
by Giovanni Toso and Piero Angeletti
Electronics 2022, 11(3), 503; https://doi.org/10.3390/electronics11030503 - 8 Feb 2022
Cited by 5 | Viewed by 2128
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)
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<p>Discrete lens architecture.</p>
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<p>Relation between excitations and far field.</p>
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<p>(<b>a</b>) Variables in the X-Z plane; (<b>b</b>) variables in the Y-Z plane.</p>
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<p>Bootlace lens with back array smaller than the front array. It exhibits a significant saving in terms of volume and a reduced field of view as compared to the back lens.</p>
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<p>Discrete lens with back array larger than the front array. It exhibits an increased field of view but a larger volume.</p>
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19 pages, 4069 KiB  
Article
Towards a Digital Twin of Coronary Stenting: A Suitable and Validated Image-Based Approach for Mimicking Patient-Specific Coronary Arteries
by Gianluca Poletti, Luca Antonini, Lorenzo Mandelli, Panagiota Tsompou, Georgia S. Karanasiou, Michail I. Papafaklis, Lampros K. Michalis, Dimitrios I. Fotiadis, Lorenza Petrini and Giancarlo Pennati
Electronics 2022, 11(3), 502; https://doi.org/10.3390/electronics11030502 - 8 Feb 2022
Cited by 15 | Viewed by 3502
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)
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<p>OCT images were used for the reconstruction of the patient-specific artery and plaque: (<b>a</b>) good OCT image quality was required both for the reconstruction of the artery from the OCT pre-treatment images and for the quantitative comparison of the OCT post-treatment lumen areas and model results; (<b>b</b>) a CNN was used to characterize the plaque types (calcified plaque (CA), fibrous tissue (FT), lipid tissue (LT), mixed tissue (MT)) from patient OCT images.</p>
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<p>Schematic representation of two potential methods to account for the mechanical behavior of in vivo arterial layers as the experimental data to be associated with the reconstructed in vivo geometry are derived from testing unloaded specimens. On the left is shown a simplified scheme describing the rationale for identifying the unloaded geometry to be used with the experimental material data: by inverse analysis, the unloaded geometry is iteratively estimated from the geometry reconstructed from the in vivo images. On the right, an alternative, simpler method is proposed: through simulations on an idealized arterial geometry of the artery, the working point corresponding to the in vivo status was identified in the experimental material data for the extrapolation of the in vivo mechanical behavior.</p>
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<p>Circumferential stress-strain curves for adventitia (<b>left</b>) and media (<b>right</b>) described with the fiber-reinforced models obtained through the pre-stretching and pressurization of the two-layered cylinder. The red dots indicate the in vivo status configuration.</p>
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<p>Validation of the strategy for modeling the media and adventitia layers with isotropic material calibrated on the circumferential in vivo behavior. On the left are the three different sizes of the healthy unloaded configuration of the idealized artery considered in the study: lumen diameters of the healthy unloaded artery of 2.7 mm (v1) (the one used for material calibration without the plaque), 3.2 mm (v2) and 2.2 mm (v3) were chosen. Starting from these geometries, three different configurations of diseased in vivo vessels were derived considering the deformations of media and adventitia under in vivo conditions and the addition of a generic plaque such as to model a 50% stenosis of the healthy lumen. Simulations of lumen pressurization of the three diseased in vivo configurations were performed for a comparison between the isotropic model calibrated on the in vivo circumferential behavior (I) and the fiber-reinforced model accounting for stresses and strains starting from the unloaded configuration (F). On the right are the simulation results in terms of lumen diameter versus the applied pressure increment beyond the physiological pressure value of 100 mmHg.</p>
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<p>Virtual model of SYNERGY™ delivery system: stent and multi-wings balloon models after crimping simulation.</p>
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<p>Sections of the 3D reconstructed geometries of the two patient-specific coronary arteries: (<b>a</b>) Case A and (<b>b</b>) Case B. The modeled components (adventitia, media, generic plaque, lipid plaque, and calcific plaque) were highlighted with different colors. For Case B bifurcation, the presence of the ostium was modeled without reconstruction of the untreated side branch.</p>
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<p>Numerical simulation results for the replication of Case A: (<b>a</b>) the geometry of artery section and stent at the end of clinical treatment; (<b>b</b>) slices orthogonal to the lumen centerline of the stented artery region used for lumen area measurements; and (<b>c</b>) graph of the lumen area as a function of the centerline coordinate with the curves related to the clinical data deduced from pre- and post-treatment OCTs and the FEA results.</p>
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<p>Numerical simulation results for the replication of Case B: (<b>a</b>) graph of the lumen area as a function of the centerline coordinate with the curves related to the clinical data deduced from pre- and post-treatment OCTs and the FEA results. The region corresponding to the bifurcation was not considered in the lumen area comparison; (<b>b</b>) the geometry of artery section and stent at the end of clinical treatment with detail on the region with overlapping stents.</p>
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16 pages, 43300 KiB  
Article
A Novel Path Voting Algorithm for Surface Crack Detection
by Jianwei Yu, Zhipeng Chen and Zhiming Xiong
Electronics 2022, 11(3), 501; https://doi.org/10.3390/electronics11030501 - 8 Feb 2022
Cited by 2 | Viewed by 2317
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)
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<p>Three example cracks. (<b>a</b>) A crack with low continuity in a 2D optic pavement image (from CrackTree206). (<b>b</b>) A pavement crack in a 3D depth image (from CrackPV14). (<b>c</b>) A crack in a material profile image (from StoneCrack50).</p>
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<p>A flowchart of the proposed method.</p>
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<p>Illustration of the weakness of the minimal-path algorithm inline structure extraction in a local subitem age. In the top row, it illustrates the weakness of minimal-path seed growing, where (<b>a</b>) is an input image, (<b>b</b>) is the seed growing results based on a seed S located at the image center, and (<b>c</b>) is the proposed adaptive <span class="html-italic">NCut</span> result. In the bottom row, it illustrates the weakness of minimal-path tracking, where (<b>d</b>) is another input image, (<b>e</b>) is the minimal-path tracking results based on two end points marked in yellow, and (<b>f</b>) is the proposed adaptive <span class="html-italic">NCut</span> result. The crack in the red circle, which has a sharp curve, cannot be tracked in the minimal-path tracking.</p>
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<p>Results generated by different path voting algorithms. (<b>a</b>) An original image. (<b>b</b>) The result was produced by the minimal-path path voting. (<b>c</b>) The result was produced by the proposed path voting.</p>
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<p>Results obtained by the proposed path voting method on simulated cracks of different widths and different noise rates. The cracks in the top row, middle row, and bottom row have the width of 1 pixel, 3 pixels, and 5 pixels, respectively. The simulated crack images have been added the ‘pepper and salt’ noise at an intensity of 0.1, 0.2, and 0.3 in the first, third, and fifth column, respectively.</p>
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<p>Crack detection results on CrackTree206 dataset. (<b>a</b>) The precision–recall curves for the comparison methods. (<b>b</b>) The performance of the proposed path voting method running at different step s and different radius r.</p>
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<p>Path voting results by using different radius r and different step length s. In the top row, the radius is fixed to be <span class="html-italic">r</span> = 11, and the step length s is varied from 1 to 7 at an interval of 2. In the bottom row, the step length is fixed to be <span class="html-italic">s</span> = 5, and the radius r is varied from 5 to 13 at an interval of 2.</p>
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<p>An illustration of the laser imaging system.</p>
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<p>Experimental results. Row 1: five pavement images with ground truth cracks (in blue) shifted, corresponding to images No. 4, 2, 5, 6, and 11 in <a href="#electronics-11-00501-t003" class="html-table">Table 3</a>. Row 2: crack maps from tensor voting (in CrackTree). Row 3: crack maps from the proposed path voting. Row 4: results from the proposed approach. Row 5: CrackTree results. Row 6: FoSA results.</p>
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20 pages, 947 KiB  
Article
Watermarking Applications of Krawtchouk–Sobolev Type Orthogonal Moments
by Edmundo J. Huertas, Alberto Lastra and Anier Soria-Lorente
Electronics 2022, 11(3), 500; https://doi.org/10.3390/electronics11030500 - 8 Feb 2022
Cited by 2 | Viewed by 1646
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)
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<p>Graph of <math display="inline"><semantics> <msubsup> <mi mathvariant="double-struck">K</mi> <mrow> <mi>n</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math> for <math display="inline"><semantics> <mrow> <mi>n</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> <mo>,</mo> <mn>4</mn> </mrow> </semantics></math>.</p>
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<p>Watermark of <math display="inline"><semantics> <mrow> <mn>64</mn> <mo>×</mo> <mn>64</mn> </mrow> </semantics></math> bits.</p>
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<p>Scrambled watermark and recovered watermark.</p>
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<p>Path followed in a matrix to transform it into a vector via <math display="inline"><semantics> <mrow> <mspace width="4pt"/> <mi mathvariant="script">Z</mi> </mrow> </semantics></math>.</p>
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<p>PSNR values of Datasets.</p>
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<p>Cropping noise.</p>
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<p>Gaussian noise.</p>
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<p>Median filter noise.</p>
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<p>Extracted watermarks under Cropping attacks. The first row corresponds to KS1Ms, KS2Ms, and KS3Ms while the second row corresponds to KMs, FrCMs, and FrCMMs.</p>
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<p>Extracted watermarks under Gaussian attacks. The first row corresponds to KS1Ms, KS2Ms, and KS3Ms while the second row corresponds to KMs, FrCMs, and FrCMMs.</p>
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<p>Salt and pepper noise.</p>
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12 pages, 14273 KiB  
Article
An Omnidirectional Platform for Education and Research in Cooperative Robotics
by Majd Kassawat, Enric Cervera and Angel P. del Pobil
Electronics 2022, 11(3), 499; https://doi.org/10.3390/electronics11030499 - 8 Feb 2022
Cited by 6 | Viewed by 2030
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)
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<p>Robot Design: (<b>a</b>) side; (<b>b</b>) front; (<b>c</b>) corner; and (<b>d</b>) real.</p>
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<p>Software components.</p>
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<p>Control Types: (<b>a</b>) single correction; (<b>b</b>) parallel corrections; (<b>c</b>) sequential corrections; and (<b>d</b>) semi-sequential corrections.</p>
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<p>Concept: (<b>a</b>) single robot scenario; and (<b>b</b>) multi-robot scenario.</p>
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<p>Setup and target object.</p>
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<p>Experiment-1 execution flow.</p>
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<p>Execution stages: (<b>a</b>) approach; (<b>b</b>) press; (<b>c</b>) lift; (<b>d</b>) hold; (<b>e</b>) set down; and (<b>f</b>) regress.</p>
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<p>Lifting angle limitation: (<b>a</b>) ready to lift; (<b>b</b>) lifted (alpha = 0 deg); (<b>c</b>) lifted (alpha = 30 deg); and (<b>d</b>) failed to lift (alpha = 40 deg).</p>
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13 pages, 11721 KiB  
Article
Design of a Broadband MMIC Driver Amplifier with Enhanced Feedback and Temperature Compensation Technique
by Shengli Zhang, Jing Wan, Jinxiang Zhao, Zhe Yang, Yuepeng Yan and Xiaoxin Liang
Electronics 2022, 11(3), 498; https://doi.org/10.3390/electronics11030498 - 8 Feb 2022
Cited by 4 | Viewed by 2771
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)
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<p>(<b>a</b>) The source and load-pull setup of the proposed structure. (<b>b</b>) Equivalent circuit model of the proposed structure.</p>
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<p>Simulated maximum gain of the first stage with and without enhanced feedback structure.</p>
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<p>Simulation of the dependence of the <math display="inline"><semantics> <msub> <mi>S</mi> <mn>21</mn> </msub> </semantics></math> for different feedback inductance values.</p>
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<p>Simulated stability factor <span class="html-italic">K</span> with and without the insertion of feedback and stable networks.</p>
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<p>Optimal impedance area in power contours of different frequency.</p>
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<p>(<b>a</b>) Schematic of the temperature compensation bias circuit. (<b>b</b>) Equivalent small-signal model of the temperature compensation bias circuit. (<b>c</b>) Current and voltage change direction with temperature.</p>
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<p>Simulation results of the temperature compensation bias circuit. (<b>a</b>) Temperature compensation circuit output voltage. (<b>b</b>) Quiescent current of the drive amplifier.</p>
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<p>Complete schematic diagram of the designed broadband driver amplifier.</p>
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<p>Photograph of the implemented broadband driver amplifier.</p>
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<p>Experimental results of the proposed driver amplifier. (<b>a</b>) Comparison between simulated (solid line) and measured (dash line) small-signal performance. (<b>b</b>) Measured stability factor of the driver amplifier.</p>
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<p>Experimental results of the proposed driver amplifier. (<b>a</b>) Comparison between simulated and measured large-signal results. (<b>b</b>) OIP3.</p>
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<p>Comparison between simulated and measured quiescent current.</p>
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14 pages, 1158 KiB  
Article
Virtual Reality Tool for Exploration of Three-Dimensional Cellular Automata
by Camilo Arevalo, Yuta Kariyado and Julián Villegas
Electronics 2022, 11(3), 497; https://doi.org/10.3390/electronics11030497 - 8 Feb 2022
Cited by 2 | Viewed by 2434
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)
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<p>Recreation of “Big beacon,” a period-8 oscillator pattern in Life described in [<a href="#B10-electronics-11-00497" class="html-bibr">10</a>].</p>
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<p>HTC VIVE controller with implemented user interface functionalities and a user in the real settings. (<b>a</b>) Controller. (<b>b</b>) Real settings.</p>
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<p>Menu and rendition mode screen shots. (<b>a</b>) Menu Mode. (<b>b</b>) Rendition Mode.</p>
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<p>DSP in the audio thread. Mono input signals coming from audio files are first band-pass filtered and then spatialized, creating a stereo signal that is sent to the audio buffer in Unity.</p>
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<p>CPU time used for the spatializer for different number of audio sources with different audio block sizes: 256 samples (Desktop version) and 1024 samples (VR version). Dashed lines indicate the block processing time in each case. (<b>a</b>) 256 samples. (<b>b</b>) 1024 samples.</p>
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<p>Results from the subjective experiment. The lines inside boxes show the median, first, and third quartiles (hinges), <math display="inline"><semantics> <mrow> <mn>1.5</mn> </mrow> </semantics></math> times the inter-quartile range left and right the hinges (whiskers), and outlying points. (<b>a</b>) UEQ. (<b>b</b>) IMI. (<b>c</b>) Virtual distance. (<b>d</b>) Scores. (<b>e</b>) Precision.</p>
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19 pages, 375 KiB  
Review
Bringing Emotion Recognition Out of the Lab into Real Life: Recent Advances in Sensors and Machine Learning
by Stanisław Saganowski
Electronics 2022, 11(3), 496; https://doi.org/10.3390/electronics11030496 - 8 Feb 2022
Cited by 50 | Viewed by 9903
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)
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<p>(<b>a</b>) The interdisciplinary background of emotion recognition; (<b>b</b>)modalities used to recognize emotions.</p>
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14 pages, 1432 KiB  
Article
A Novel Deep Learning Model for Detection of Severity Level of the Disease in Citrus Fruits
by Poonam Dhiman, Vinay Kukreja, Poongodi Manoharan, Amandeep Kaur, M. M. Kamruzzaman, Imed Ben Dhaou and Celestine Iwendi
Electronics 2022, 11(3), 495; https://doi.org/10.3390/electronics11030495 - 8 Feb 2022
Cited by 200 | Viewed by 7126
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
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<p>The overall process of detection of the citrus fruit disease severity levels.</p>
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<p>Original image and segmented image sample of citrus fruit.</p>
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<p>(<b>a</b>) Labels on original image and on Felzenszwalb-segmentated image; (<b>b</b>) Felzenszwalb-segmented image.</p>
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<p>Texture gradient for LBP feature.</p>
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<p>HSV image with min–max values.</p>
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<p>Intersection of Union on overlapped region.</p>
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<p>Proposed CNN model with transfer learning.</p>
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<p>Loss and accuracy curves of the implemented model.</p>
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<p>Result showing four levels of severity in image samples.</p>
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18 pages, 3931 KiB  
Article
Threat Analysis and Distributed Denial of Service (DDoS) Attack Recognition in the Internet of Things (IoT)
by Mohammed Hasan Ali, Mustafa Musa Jaber, Sura Khalil Abd, Amjad Rehman, Mazhar Javed Awan, Robertas Damaševičius and Saeed Ali Bahaj
Electronics 2022, 11(3), 494; https://doi.org/10.3390/electronics11030494 - 8 Feb 2022
Cited by 71 | Viewed by 6314
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)
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<p>Data balancing model structure and its process.</p>
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<p>Intelligent Intrusion Detection System in the Internet of Things (IoT).</p>
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<p>Intruder actions training using long-short term network.</p>
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<p>IoT Experimental Structure of Intrusion Detection System.</p>
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<p>Confusion matrix of classification results: (<b>a</b>) training, (<b>b</b>) validation, (<b>c</b>) test, and (<b>d</b>) full.</p>
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<p>Confusion matrix of classification results: (<b>a</b>) training, (<b>b</b>) validation, (<b>c</b>) test, and (<b>d</b>) full.</p>
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<p>Classification results: (<b>a</b>) Precision and (<b>b</b>) Recall.</p>
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<p>False Alarm Rate.</p>
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<p>Threat defections on attackers.</p>
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<p>Overall performance analysis.</p>
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21 pages, 22080 KiB  
Article
An Optimal Procedure for the Design of Discrete Constrained Lens Antennas with Minimized Optical Aberrations. Part I: Two-Dimensional Architectures
by Giovanni Toso and Piero Angeletti
Electronics 2022, 11(3), 493; https://doi.org/10.3390/electronics11030493 - 8 Feb 2022
Cited by 4 | Viewed by 1823
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)
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<p>Variables defining a two-dimensional constrained lens.</p>
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<p>(<b>a</b>) Three possible focal arcs; (<b>b</b>) associated aberrations. Continuous line: circular arc; dashed line: according to Equation (2) and linear interpolation; dash-dotted line: according to Equation (2) and local optimization.</p>
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<p>(<b>a</b>) Three possible focal arcs; (<b>b</b>) associated aberrations. Continuous line: circular arc; dashed line: according to Equation (2) and linear interpolation; dash-dotted line: according to Equation (2) and local optimization.</p>
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<p>Three possible focal arcs in Cartesian coordinates. Continuous line: circular arc; dashed line: according to Equation (2) and linear interpolation; dash-dotted line: according to Equation (2) and local optimization.</p>
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<p>Optimized internal angle δ [degrees] in the 4-foci lens as compared to the external angle α [degrees]: dots = numerical evaluations, black continuous line = heuristic curve (6).</p>
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<p>Aberrations of a 4-foci lens when the feed is assumed in the position of the 5th axial focus.</p>
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<p>Normalized maximum phase error for the ~5-foci lenses with F/D = 1 before and after the removal of linear aberrations.</p>
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<p>Maximum aberrations [degrees] as a function of the maximum scanning angle [degrees] for three different values of the F/D. Continuous line: F/D = 1; dashed curve: F/D = 1.25; dotted curve: F/D = 1.5.</p>
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18 pages, 4247 KiB  
Article
A Comprehensive Virtual Synchronous Generator Control Strategy for Harmonic and Imbalance Voltage Suppression of Multi-Inverter Parallel Microgrid
by Yannan Dong, Shaohua Ma, Zijiao Han, Henan Dong and Xiangjun Li
Electronics 2022, 11(3), 492; https://doi.org/10.3390/electronics11030492 - 8 Feb 2022
Cited by 6 | Viewed by 2726
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)
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<p>Virtual synchronous generator control loops.</p>
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<p>The block diagram of secondary control strategy.</p>
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<p>The block diagram of main control strategy.</p>
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<p>Transformation of the uniform coordinate system.</p>
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<p>The system root locus diagram for the changes of <span class="html-italic">J</span> and <span class="html-italic">K</span>. (<b>a</b>) The root locus of the inertia coefficient <span class="html-italic">J</span> of the VSG changes from 0.04 to 10; (<b>b</b>) the root locus of the excitation coefficient <span class="html-italic">K</span> of the VSG changes from 0.001 to 100.</p>
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<p>The system root locus diagram for the changes of <span class="html-italic">D<sub>p</sub></span> and <span class="html-italic">D<sub>q</sub></span>. (<b>a</b>) The root locus of the droop coefficient <span class="html-italic">D<sub>p</sub></span> of the VSG changes from 0 to 500; (<b>b</b>) the root locus of the droop coefficient <span class="html-italic">D<sub>q</sub></span> of the VSG changes from 0 to 1000.</p>
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<p>The system root locus diagram for the changes of <span class="html-italic">R<sub>v</sub></span> and <span class="html-italic">X<sub>v</sub></span>. (<b>a</b>) The root locus of virtual resistance <span class="html-italic">R<sub>v</sub></span> changes from 0 to 0.8; (<b>b</b>) the root locus of virtual reactance <span class="html-italic">X<sub>v</sub></span> changes from 0 to 0.8.</p>
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<p>The root locus diagram of the parameters used in the experiment.</p>
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<p>Experiments setup with RTLAB real-time simulation system.</p>
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<p>Experimental results for frequency waveform comparison of droop control and VSG control.</p>
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<p>Experimental results for the waveform of imbalances ratio (<b>a</b>) with the traditional PI control strategy; (<b>b</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG; (<b>c</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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<p>Experimental results for the waveform of imbalances ratio (<b>a</b>) with the traditional PI control strategy; (<b>b</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG; (<b>c</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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<p>Experimental results for the FFT analysis harmonic waveform (<b>a</b>) with the traditional PI control strategy; (<b>b</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG; (<b>c</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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<p>Experimental results for the voltage waveform of microgrid for PCC point (<b>a</b>) without the harmonic voltage suppression of multi-inverter parallel VSG adding a secondary control strategy; (<b>b</b>) with the harmonic voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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<p>Experimental results for the frequency waveform (<b>a</b>) with the traditional PI control strategy; (<b>b</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG; (<b>c</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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<p>Experimental results for the waveform of voltage RMS for PCC (<b>a</b>) with the traditional PI control strategy; (<b>b</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG; (<b>c</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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<p>Experimental results for the voltage waveform of microgrid for PCC point (<b>a</b>) without the imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy; (<b>b</b>) with the harmonic and imbalance voltage suppression of multi-inverter parallel VSG adding a secondary control strategy.</p>
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17 pages, 4990 KiB  
Article
Solar Energy Compensation for Building Energy Saving with Thermal Comfort in a Cold Climate
by Xiangping Chen, Yongxiang Cai, Xiaobing Xiao, Youzhuo Zheng and Anqian Yang
Electronics 2022, 11(3), 491; https://doi.org/10.3390/electronics11030491 - 8 Feb 2022
Viewed by 2053
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)
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<p>A controller in BCVTB interacts with ENERGYPLUS environment.</p>
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<p>Model structure in BCVTB environment.</p>
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<p>A simple building plan.</p>
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<p>Wind speed variation over the four days.</p>
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<p>Outdoor temperature variation over the four days.</p>
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<p>Solar radiation over the four days.</p>
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<p>State-transmitting chart for blinding operation.</p>
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<p>The waveform of indoor temperature under different strategies.</p>
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<p>PMV variation under different operations.</p>
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<p>PPD variation under different operations.</p>
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<p>Indoor temperature variation vs. blind-shading scheme.</p>
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<p>PMV variation during optimal operation.</p>
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<p>PMV variation during optimal operation.</p>
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<p>Energy consumption during heating by HVAC.</p>
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<p>Energy consumption during cooling by HVAC.</p>
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<p>Accumulative energy consumption.</p>
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16 pages, 1360 KiB  
Article
An Energy-Saving Scheduling Algorithm for Multipath TCP in Wireless Networks
by Pingping Dong, Rongcheng Shen, Yajing Li, Cheng Nie, Jingyun Xie, Kai Gao and Lianming Zhang
Electronics 2022, 11(3), 490; https://doi.org/10.3390/electronics11030490 - 8 Feb 2022
Cited by 10 | Viewed by 2799
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 Section Artificial Intelligence)
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<p>MPTCP protocol stack.</p>
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<p>3G+WLAN scenario. (<b>a</b>) The total energy with different file sizes; (<b>b</b>) The Goodput with different file sizes.</p>
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<p>The proportion (%) of the packets transferred over the WLAN path with different file sizes in the 3G+WLAN scenario.</p>
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<p>The Goodput with different file sizes over the WLAN path in the 3G+WLAN scenario.</p>
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<p>The retransmission rate with different file sizes in 3G+WLAN scenario.</p>
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<p>The completion time with different file sizes in the 3G+WLAN scenario.</p>
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<p>Experimental topology.</p>
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<p>3G+WLAN scenario. (<b>a</b>) The total energy with different file sizes; (<b>b</b>) The Goodput with different file sizes; (<b>c</b>) The energy efficiency with different file sizes.</p>
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<p>3G and WLAN path. (<b>a</b>) The Goodput with different file sizes; (<b>b</b>) The total energy with different file sizes.</p>
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<p>WLAN+WLAN scenario. (<b>a</b>) The total energy with different file sizes; (<b>b</b>) The Goodput with different file sizes.</p>
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14 pages, 4602 KiB  
Article
Effect of Phase Noise on the Optical Millimeter-Wave Signal in the DWDM-RoF System
by Rawa Muayad Mahmood, Syamsuri Yaakob, Faisul Arif Ahmad, Siti Barirah Ahmad Anas, Muhammad Zamzuri Abdul Kadir and Mohd Rashidi Che Beson
Electronics 2022, 11(3), 489; https://doi.org/10.3390/electronics11030489 - 8 Feb 2022
Cited by 3 | Viewed by 2381
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)
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<p>The phase imbalance in MZM: (<b>a</b>) MZM diagram and (<b>b</b>) phase difference in the mm-wave signal.</p>
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<p>The schematic diagram of an MZM.</p>
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<p>The block diagram of the DWDM-RoF system.</p>
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<p>The optical spectrum analyzer for transmitted signals: (<b>a</b>) first signal and (<b>b</b>) 8 signals modulated together.</p>
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<p>The 60 GHz mm-wave in the DWDM-RoF system.</p>
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<p>The phase imbalance vs. the applied phases at PS.</p>
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<p>The constellation diagram of phase noise at different phase imbalances (<b>a</b>) at π/12(<b>b</b>) at π/6 (<b>c</b>) at π/4 (<b>d</b>) at π/3 and (<b>e</b>) at 5π/12.</p>
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<p>The optical mm-wave signal, the input signal, and the output signal.</p>
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<p>BER vs. OSNR of the mm-wave signal in the DWDM-RoF system.</p>
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<p>BER vs. SNR of the mm-wave signal in the DWDM-RoF system.</p>
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<p>The EVM vs. the phase noise of the mm-wave signal.</p>
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<p>The mm-wave signal before and after controlling the phase imbalance in the DWDM-RoF system.</p>
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20 pages, 5151 KiB  
Article
BAIV: An Efficient Blockchain-Based Anonymous Authentication and Integrity Preservation Scheme for Secure Communication in VANETs
by Azees Maria, Arun Sekar Rajasekaran, Fadi Al-Turjman, Chadi Altrjman and Leonardo Mostarda
Electronics 2022, 11(3), 488; https://doi.org/10.3390/electronics11030488 - 8 Feb 2022
Cited by 25 | Viewed by 3645
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)
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<p>Proposed system model for VANET.</p>
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<p>Linkage of blocks in blockchain network.</p>
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<p>Simulation result of vehicle user authentication.</p>
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<p>Simulation result of RSU authentication.</p>
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<p>Simulation result of message transmission.</p>
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<p>Simulation results for the computational cost of different schemes.</p>
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<p>Graphical representation of computational cost.</p>
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<p>RSU serving capability.</p>
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13 pages, 3348 KiB  
Article
Ultrawideband Cross-Polarization Converter Using Anisotropic Reflective Metasurface
by Tauqir Ahmad, Arbab Abdur Rahim, Rana Muhammad Hasan Bilal, Adnan Noor, Husnul Maab, Muhammad Ashar Naveed, Abdullah Madni, Muhammad Mahmood Ali and Muhammad Ahsan Saeed
Electronics 2022, 11(3), 487; https://doi.org/10.3390/electronics11030487 - 8 Feb 2022
Cited by 42 | Viewed by 4238
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
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<p>Schematic diagram of the proposed meta−unit cell structure: (<b>a</b>) front view, (<b>b</b>) side view.</p>
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<p>Design process along with respective reflection characteristics of the proposed anisotropic reflective metasurface with (<b>a</b>) a <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>45</mn> </mrow> <mo>∘</mo> </msup> </mrow> </semantics></math> rotated square patch, (<b>b</b>) a rectangular split width of 0.4 mm is employed at <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>45</mn> </mrow> <mo>∘</mo> </msup> </mrow> </semantics></math> rotation with respect to <span class="html-italic">xy</span>−axes, (<b>c</b>) a triangular part is cut off from the lower portion, and (<b>d</b>) a rhombus−like shape is removed from <math display="inline"><semantics> <mrow> <msup> <mrow> <mn>45</mn> </mrow> <mo>∘</mo> </msup> </mrow> </semantics></math> rotated square patch.</p>
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<p>Polarization conversion response of proposed metasurface: (<b>a</b>) co− and cross− polarization component <math display="inline"><semantics> <mrow> <msub> <mi>r</mi> <mrow> <mi>y</mi> <mi>y</mi> </mrow> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>r</mi> <mrow> <mi>x</mi> <mi>y</mi> </mrow> </msub> </mrow> </semantics></math>, (<b>b</b>) polarization conversion ratio (<span class="html-italic">PCR</span>), (<b>c</b>) magnitude of orthogonal components <math display="inline"><semantics> <mrow> <msub> <mi>r</mi> <mi>u</mi> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>r</mi> <mi>v</mi> </msub> </mrow> </semantics></math>, and (<b>d</b>) phase difference.</p>
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<p>Illustration of the decomposition of orthogonal components <span class="html-italic">u</span> and <span class="html-italic">v</span> in reflection mode.</p>
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<p>Surface current distribution of the proposed anisotropic reflective metasurface at the top and bottom metallic layers at various resonant frequencies. (<b>a</b>,<b>b</b>) 13.8 GHz, (<b>c</b>,<b>d</b>) 19.7 GHz.</p>
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<p>(<b>a</b>) Schematic representation of the proposed anisotropic reflective metasurface under oblique incident wave; (<b>b</b>) angular dependent <span class="html-italic">PCR</span> of the proposed anisotropic reflective metasurface.</p>
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<p>(<b>a</b>) Co− and cross−polarization component <span class="html-italic">r<sub>yy</sub></span> and <span class="html-italic">r<sub>xy</sub></span>; (<b>b</b>) Polarization conversion ratio (<span class="html-italic">PCR</span>); (<b>c</b>) Magnitude of orthogonal components <span class="html-italic">r<sub>u</sub></span> and <span class="html-italic">r<sub>v</sub></span>; (<b>d</b>) Phase difference.</p>
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18 pages, 523 KiB  
Article
A Novel Android Botnet Detection System Using Image-Based and Manifest File Features
by Suleiman Y. Yerima and Abul Bashar
Electronics 2022, 11(3), 486; https://doi.org/10.3390/electronics11030486 - 8 Feb 2022
Cited by 19 | Viewed by 4177
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)
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<p>Overview of the different steps involved in building the image-based Android botnet detection system.</p>
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<p>Building a Histogram of Oriented Gradients using nine bins representing positive orientations spaced 20 degrees apart.</p>
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<p>Overall classification accuracy for the various classifiers using the three compared schemes.</p>
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<p>Average training times for the training set samples in seconds for each of the ML classifiers using our proposed scheme.</p>
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19 pages, 387 KiB  
Article
Mobile Broadband Performance Evaluation: Analysis of National Reports
by Yalew Zelalem Jembre, Woon-young Jung, Muhammad Attique, Rajib Paul and Beomjoon Kim
Electronics 2022, 11(3), 485; https://doi.org/10.3390/electronics11030485 - 8 Feb 2022
Cited by 7 | Viewed by 3009
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)
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<p>IMT-2020 (5G) vs. IMT-Advanced (4G) [<a href="#B2-electronics-11-00485" class="html-bibr">2</a>].</p>
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<p>Applications and services in IMT-2020 (5G) [<a href="#B2-electronics-11-00485" class="html-bibr">2</a>].</p>
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16 pages, 2223 KiB  
Article
Driver Cardiovascular Disease Detection Using Seismocardiogram
by Gediminas Uskovas, Algimantas Valinevicius, Mindaugas Zilys, Dangirutis Navikas, Michal Frivaldsky, Michal Prauzek, Jaromir Konecny and Darius Andriukaitis
Electronics 2022, 11(3), 484; https://doi.org/10.3390/electronics11030484 - 7 Feb 2022
Cited by 5 | Viewed by 3278
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
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<p>Driver seismocardiogram measurement system with two accelerometers. (<b>a</b>) Driver seismocardiogram measurement system inside car. (<b>b</b>) Structure of measurement data collection and processing system.</p>
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<p>Resultant of three accelerometer coordinates.</p>
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<p>Fundamental adaptive filter configuration.</p>
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<p>Adaptive filter configuration.</p>
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<p>Processing of the driver’s seismocardiogram signal in the third adaptive filter with sample delay order of 5 and the FIR filter in the input. (<b>a</b>) SCG signal on input. (<b>b</b>) Adaptation error of the third adaptive filter. (<b>c</b>) Adaptively filtrated signal. (<b>d</b>) The efficiency of the adaptative filter.</p>
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<p>The fourth adaptive filter. (<b>a</b>) Adaptation error of the fourth adaptive filter. (<b>b</b>) The fourth adaptively filtrated signal. (<b>c</b>) Adaptation efficiency.</p>
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<p>Signal-to-noise rate’s dependence on the adaptive filter order.</p>
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<p>Driver seismocardiogram after the fourth adaptive filter and detected peaks.</p>
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<p>Autocorrelations of the filtered seismocardiogram signals.</p>
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17 pages, 21370 KiB  
Article
A Non-Isolated Hybrid Zeta Converter with a High Voltage Gain and Reduced Size of Components
by Padala Lakshmi Santosh Kumar Reddy, Yeddula Pedda Obulesu, Srinivas Singirikonda, Mosleh Al Harthi, Mohammed S. Alzaidi and Sherif S. M. Ghoneim
Electronics 2022, 11(3), 483; https://doi.org/10.3390/electronics11030483 - 7 Feb 2022
Cited by 7 | Viewed by 3060
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
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<p>Proposed hybrid Zeta converter.</p>
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<p>The proposed converter’s waveforms for one switching interval.</p>
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<p>The proposed hybrid Zeta converter equivalent circuits. (<b>a</b>) Mode-1 (<b>b</b>) Mode-2 (<b>c</b>) Mode-3.</p>
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<p>The Eigenvalues of matrix ‘A’.</p>
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<p>Voltage gain comparison of the proposed converter and similar converters.</p>
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<p>Output wave forms of step-up mode. (<b>a</b>) Output voltage, (<b>b</b>) output current, (<b>c</b>) inductor current (I<sub>L1</sub>), (<b>d</b>) inductor current (I<sub>L2</sub>), and (<b>e</b>) capacitor voltage (V<sub>C1</sub>).</p>
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<p>Output wave forms of step-down mode. (<b>a</b>) Output voltage, (<b>b</b>) output current, (<b>c</b>) inductor current (I<sub>L1</sub>), (<b>d</b>) inductor current (I<sub>L2</sub>), and (<b>e</b>) capacitor voltage (V<sub>C1</sub>).</p>
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<p>Output wave forms of step-down mode. (<b>a</b>) Output voltage, (<b>b</b>) output current, (<b>c</b>) inductor current (I<sub>L1</sub>), (<b>d</b>) inductor current (I<sub>L2</sub>), and (<b>e</b>) capacitor voltage (V<sub>C1</sub>).</p>
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<p>HIL experimental set-up of the proposed Zeta converter.</p>
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<p>Output wave forms of step-up mode. (<b>a</b>) Output voltage and output current, (<b>b</b>) voltage across inductors (I<sub>L1</sub> and I<sub>L2</sub>), and (<b>c</b>) capacitor voltage (V<sub>C1</sub>).</p>
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<p>Output waveforms of step-down mode. (<b>a</b>) Output voltage and output current, (<b>b</b>) inductor voltage (I<sub>L1</sub> and I<sub>L2</sub>), and (<b>c</b>) capacitor voltage (V<sub>C1</sub>).</p>
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<p>Output waveforms of step-down mode. (<b>a</b>) Output voltage and output current, (<b>b</b>) inductor voltage (I<sub>L1</sub> and I<sub>L2</sub>), and (<b>c</b>) capacitor voltage (V<sub>C1</sub>).</p>
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<p>Efficiency and loss distributions. (<b>a</b>) Efficiency curve and (<b>b</b>) losses distributions under V<sub>0</sub> = 72 v, P<sub>0</sub> = 173 W.</p>
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<p>Efficiency and loss distributions. (<b>a</b>) Efficiency curve and (<b>b</b>) losses distributions under V<sub>0</sub> = 72 v, P<sub>0</sub> = 173 W.</p>
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13 pages, 4751 KiB  
Article
Digital Pole Control for Speed and Torque Variation in an Axial Flux Motor with Permanent Magnets
by Adrián González-Parada, José Merced Lozano-García and Mario Alberto Ibarra-Manzano
Electronics 2022, 11(3), 482; https://doi.org/10.3390/electronics11030482 - 7 Feb 2022
Cited by 1 | Viewed by 2064
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)
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<p>Electric motor whit 3 magnetic poles in stator, and 2 magnetic poles in rotor: (<b>a</b>) 3 magnetic poles stator; (<b>b</b>) 2 magnetic pole rotors.</p>
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<p>Magnetic sequences for rotation clockwise of the motor.</p>
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<p>Magnetic polarization sequences in the three stator coils.</p>
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<p>Speed with respect to electrical frequency.</p>
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<p>Switching sequences for CT1 configuration.</p>
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<p>Switching signals of the twelve magnetic poles for CT1.</p>
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<p>Switching sequences for CT6 configuration.</p>
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<p>Switching signals of the twelve magnetic poles for CT6.</p>
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<p>Block diagram of speed and torque control system.</p>
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<p>Permanent magnet axial flow motor prototype: (<b>a</b>) Motor stator; (<b>b</b>) Motor rotor.</p>
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<p>System used to measure dynamic characteristics.</p>
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<p>Behavior speed–frequency.</p>
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<p>Speed–torque performance for all six configurations in AFM.</p>
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<p>Speed–power performance for all six configurations in AFM.</p>
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15 pages, 7153 KiB  
Article
Content-Addressable Memory System Using a Nanoelectromechanical Memory Switch
by Hyunju Kim, Mannhee Cho, Sanghyun Lee, Hyug Su Kwon, Woo Young Choi and Youngmin Kim
Electronics 2022, 11(3), 481; https://doi.org/10.3390/electronics11030481 - 7 Feb 2022
Cited by 4 | Viewed by 4442
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)
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<p>Comparison of content-addressable memory (CAM) and random-access memory (RAM).</p>
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<p>CAM cell structure: (<b>a</b>) 9-T binary CAM (BCAM); (<b>b</b>) 10-T BCAM; and (<b>c</b>) 17-T ternary CAM (TCAM) [<a href="#B7-electronics-11-00481" class="html-bibr">7</a>].</p>
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<p>Precharge circuit of (<b>a</b>) bit line (BL) and search line (SL); and (<b>b</b>) match line (ML) [<a href="#B4-electronics-11-00481" class="html-bibr">4</a>,<a href="#B5-electronics-11-00481" class="html-bibr">5</a>].</p>
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<p>Schematic design of (<b>a</b>) SRAM-based BCAM cell; and (<b>b</b>) data encoding for write and search [<a href="#B7-electronics-11-00481" class="html-bibr">7</a>].</p>
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<p>Local and global masking of a TCAM [<a href="#B28-electronics-11-00481" class="html-bibr">28</a>].</p>
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<p>Schematic design of (<b>a</b>) CMOS-based TCAM cell; and (<b>b</b>) data encodings for write and search [<a href="#B7-electronics-11-00481" class="html-bibr">7</a>].</p>
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<p>Design of nanoelectromechanical (NEM) memory switch [<a href="#B25-electronics-11-00481" class="html-bibr">25</a>].</p>
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<p>Schematic of a nanoelectromechanical (NEM) memory cell.</p>
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<p>Schematic design of (<b>a</b>) NEM-based CAM cell; and (<b>b</b>) data encodings for write and search.</p>
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<p>Layout design of NEM-based CAM cell and memory switch.</p>
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<p>(<b>a</b>) Schematic and (<b>b</b>) layout of a 10 × 10 array design.</p>
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<p>Pre-layout simulation of the single-bit NEM-based BCAM. (<b>a</b>) write 0, search 0, ‘match’; and (<b>b</b>) write 1, search 0, ‘mismatch’.</p>
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<p>Pre-layout simulation of a single-bit NEM-based TCAM. (<b>a</b>) write X, search 1, ‘match’; and (<b>b</b>) write 1, search X, ‘match’.</p>
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<p>Post-layout simulation of the NEM-based TCAM10 × 10 array. (<b>a</b>) Transient simulation; and (<b>b</b>) test bench.</p>
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<p>Die photo and 1 × 1 NEM-based CAM for movable-beam operation verification.</p>
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<p>(<b>a</b>) Current-voltage curve of the NEM memory switch; and (<b>b</b>) conceptual illustration of beam movement by voltages.</p>
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<p>DC supply, oscilloscope, and chip-on-board (COB) setting for experiment.</p>
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<p>Timing waveforms confirmed by oscilloscope of 1 × 1 NEM-based CAM, where a ‘0’ value is written when searching. (<b>a</b>) ‘0’ results in a match and (<b>b</b>) ‘1’ results in a mismatch.</p>
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15 pages, 4821 KiB  
Article
Demystifying Non-Isolated DC–DC Topologies on Partial Power Processing Architectures
by Jon Anzola, Iosu Aizpuru, Asier Arruti, Jesus Sergio Artal-Sevil and Carlos Bernal
Electronics 2022, 11(3), 480; https://doi.org/10.3390/electronics11030480 - 6 Feb 2022
Cited by 3 | Viewed by 2391
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
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<p>Power flow diagram. (<b>a</b>) FPP. (<b>b</b>) PPP.</p>
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<p>PPC architectures. (<b>a</b>) IPOS. (<b>b</b>) FC.</p>
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<p>HB topology implemented on a (<b>a</b>) FPC architecture and a (<b>b</b>) FC-type PPC architecture.</p>
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<p>Current and voltage steady-state waveforms at the single-inductor topology (<b>a</b>) inductor, (<b>b</b>) semiconductor, and (<b>c</b>) capacitor.</p>
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<p>Current and voltage steady-state waveforms at the single-inductor topology (<b>a</b>) inductor, (<b>b</b>) semiconductor, and (<b>c</b>) capacitor.</p>
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<p>MSIBC topology implemented on a (<b>a</b>) FPC architecture, (<b>b</b>) an FC-type PPC architecture, and (<b>c</b>) a switching sequence between an FPC-MSIBC and a PPC-MSIBC.</p>
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<p>Inductor’s current and voltage steady-state waveforms for the double-inductor topology.</p>
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<p>Capacitor’s current and voltage steady-state waveforms for the double-inductor topology.</p>
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<p>Mounted inductance for the (<b>a</b>) HB (<math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>150</mn> <mo> </mo> <mrow> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">H</mi> </mrow> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mi>L</mi> </msub> <mo>=</mo> <mn>26</mn> <mrow> <mtext> </mtext> <mi mathvariant="normal">m</mi> <mi mathvariant="sans-serif">Ω</mi> </mrow> </mrow> </semantics></math>) and (<b>b</b>) MSIBC (<math display="inline"><semantics> <mrow> <mi>L</mi> <mo>=</mo> <mn>75</mn> <mo> </mo> <mrow> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">H</mi> </mrow> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mi>R</mi> <mi>L</mi> </msub> <mo>=</mo> <mn>31</mn> <mrow> <mtext> </mtext> <mi mathvariant="normal">m</mi> <mi mathvariant="sans-serif">Ω</mi> </mrow> </mrow> </semantics></math>).</p>
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<p>Assembled full-bridge prototype. (<b>a</b>) High level schematic. (<b>b</b>) Power layer. (<b>c</b>) Driver layer.</p>
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<p>Experimental set-up. (<b>a</b>) FPC. (<b>b</b>) FC-type PPC.</p>
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<p>The setup for the experimental tests.</p>
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<p>Experimental inductor current obtained by the single-inductor topology.</p>
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<p>Experimental inductor current attained by the double-inductor topology.</p>
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<p>Semiconductors’ temperature evolution at the MSIBC. (<b>a</b>) FPC. (<b>b</b>) PPC.</p>
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<p>(<b>a</b>) Simplified diagram of a HB topology. (<b>b</b>) Simplified diagram of a MSIBC topology.</p>
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<p>Boost mode operation. (<b>a</b>) Switching state 1. (<b>b</b>) Switching state 2.</p>
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<p>Buck mode operation. (<b>a</b>) Switching state 1. (<b>b</b>) Switching state 2.</p>
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9 pages, 2593 KiB  
Article
Effect of Dielectric Thickness on Resistive Switching Polarity in TiN/Ti/HfO2/Pt Stacks
by Guillermo Vinuesa, Héctor García, Mireia B. González, Kristjan Kalam, Miguel Zabala, Aivar Tarre, Kaupo Kukli, Aile Tamm, Francesca Campabadal, Juan Jiménez, Helena Castán and Salvador Dueñas
Electronics 2022, 11(3), 479; https://doi.org/10.3390/electronics11030479 - 6 Feb 2022
Cited by 7 | Viewed by 2822
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)
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<p>(<b>a</b>) Layout of the cross-point configuration. (<b>b</b>) Cross-section of the device.</p>
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<p>Current-Voltage curves of a TiN/Ti/HfO<sub>2</sub>/Pt sample with a HfO<sub>2</sub> thickness of (<b>a</b>) 8 nm and (<b>b</b>) 13 nm. The red curve represents an average of the 50 I-V loop shown in grey.</p>
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<p>Electroforming process of a TiN/Ti/HfO<sub>2</sub>/Pt sample with a HfO<sub>2</sub> thickness of (<b>a</b>) 8 nm and (<b>b</b>) 13 nm.</p>
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<p>Resistive switching behaviour of the 8 nm film after a negative electroforming process. (<b>a</b>) 1st cycle after the electroforming. Positive voltage is applied first to initiate the RESET event and to invert the polarity. However, it does not occur (step 1), rather, a RESET can be seen when negative voltage is applied (step 2). (<b>b</b>) Two subsequent cycles, the sample still demonstrates CCW RS.</p>
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<p>Resistive switching behaviour of the 13 nm film after a positive electroforming process. (<b>a</b>) 1st cycle after the electroforming. A negative voltage was applied to trigger the RESET event and confirm that the polarity had inverted (step 1). However, the device presented an anomalous peak resembling a failed SET event (step 2) after which a RESET occurs (step 3). (<b>b</b>) Two subsequent cycles, the sample still demonstrates CW RS.</p>
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<p>Proposed resistive switching mechanism for the (<b>a</b>) 8 nm and (<b>b</b>) 13 nm thick HfO<sub>2</sub> samples.</p>
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13 pages, 30920 KiB  
Article
Features and Always-On Wake-Up Detectors for Sparse Acoustic Event Detection
by Marko Gazivoda, Dinko Oletić and Vedran Bilas
Electronics 2022, 11(3), 478; https://doi.org/10.3390/electronics11030478 - 6 Feb 2022
Cited by 6 | Viewed by 2438
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)
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<p>Spectro-temporal decomposition wake-up detector generalized architecture.</p>
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<p>Level-crossing rate wake-up detector generalized architecture.</p>
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<p>(<b>a</b>) Speedboat passing signal and (<b>b</b>) its spectrogram.</p>
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<p>Spectro-temporal decomposition wake-up detector from [<a href="#B38-electronics-11-00478" class="html-bibr">38</a>]: (<b>a</b>) schematic and (<b>b</b>) photograph.</p>
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<p>Microcontroller state machine implementation and event detection scheme. <span class="html-italic">Ch</span><sub>1</sub> to <span class="html-italic">Ch</span><sub>3</sub> and the three colored lines (green, blue and red) represent each channel’s comparator output, and <span class="html-italic">S</span><sub>0</sub> to <span class="html-italic">S</span><sub>k</sub> are the state machine states, each lasting 0.5 s. (<b>a</b>) Event detected: at least 2 and no more than 9 consecutive states have all 3 comparator outputs in a high state, and a wake-up signal is generated. (<b>b</b>) No event detected: the total <span class="html-italic">S</span><sub>0</sub> to <span class="html-italic">S</span><sub>14</sub> sequence passes without meeting the detection condition, no wake-up signal is generated.</p>
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<p>Novel level-crossing rate wake-up detector: (<b>a</b>) schematic and (<b>b</b>) photograph.</p>
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<p>Experimental setup, with marked components: (1) power source, (2) waveform generator, (3) tested detector PCB, (4) data acquisition card, and (5) multimeter.</p>
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<p>Comparison of speedboat passing detections at given SNR with selected detectors.</p>
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15 pages, 10941 KiB  
Article
Data Preprocessing Combination to Improve the Performance of Quality Classification in the Manufacturing Process
by Eunnuri Cho, Tai-Woo Chang and Gyusun Hwang
Electronics 2022, 11(3), 477; https://doi.org/10.3390/electronics11030477 - 6 Feb 2022
Cited by 20 | Viewed by 4623
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)
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<p>Creation of TomekLinks.</p>
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<p>GAN framework.</p>
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<p>Framework for imputation and imbalance adjustment.</p>
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<p>Example of identifying a missing value in the data of feature 562.</p>
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<p>F1 scores for each of the methodologies.</p>
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14 pages, 5793 KiB  
Article
Bin-Picking Solution for Randomly Placed Automotive Connectors Based on Machine Learning Techniques
by Pedro Torres, Janis Arents, Hugo Marques and Paulo Marques
Electronics 2022, 11(3), 476; https://doi.org/10.3390/electronics11030476 - 6 Feb 2022
Cited by 12 | Viewed by 3382
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
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<p>Bin-picking concept applied to unsorted small plastic connectors.</p>
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<p>(<b>a</b>) Boxes of connectors for reuse. (<b>b</b>,<b>c</b>) Sample of some of the connectors used for recognition, in different poses.</p>
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<p>Layout concept for the Bin-Picking Station.</p>
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<p>Typical tasks performed in the object recognition training process.</p>
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<p>Creating references through a labeling application.</p>
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<p>YOLOv5 architecture.</p>
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<p>Coordinates reference system.</p>
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<p>Obtained confusion matrix for Setup 1.</p>
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<p>Setup 1 output results using the YOLO5vs algorithm.</p>
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<p>Setup 1 classification results using the YOLOv5s algorithm.</p>
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<p>Confusion matrix for Setup 2.</p>
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<p>Setup 2 output results using the YOLOv5s algorithm.</p>
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<p>Setup 2 classification results using the YOLOv5s algorithm.</p>
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<p>Steps in identifying connector orientation. (<b>a</b>) search for a shape and orientation. (<b>b</b>) approach to the shape. (<b>c</b>) matching shape.</p>
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20 pages, 2126 KiB  
Article
An Optimization Framework for the Design of High-Speed PCB VIAs
by Gianfranco Avitabile, Antonello Florio, Vito Leonardo Gallo, Alessandro Pali and Lorenzo Forni
Electronics 2022, 11(3), 475; https://doi.org/10.3390/electronics11030475 - 6 Feb 2022
Cited by 2 | Viewed by 4868
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)
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<p>Figures of Merit and configuration of VIA ports.</p>
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<p>Reference structures: (<b>a</b>) An <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>=</mo> <mn>12</mn> </mrow> </semantics></math> layer stack-up; (<b>b</b>) different VIA structures.</p>
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<p>Sketch of the geometrical parameters (<b>a</b>) Planar view and parameters for the differential pair and the stitching couple (<b>b</b>) Nomenclature for the diameters and PtP distances (<b>c</b>) Diameters for the capture land and target land of the VIA (<b>d</b>) Front view and parameters taking into account the slant (<b>e</b>) Stitching VIA parameters.</p>
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<p>The three-step analysis and optimization framework presented in this paper.</p>
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<p>Reference schematic circuit for the simulation of the S-parameters. The black-box element in the center contains the EM model of the stack-up for the current simulation.</p>
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<p>FoMs of the reference VIA structure—<math display="inline"><semantics> <msub> <mi>L</mi> <mrow> <mn>1</mn> <mo>,</mo> <mn>3</mn> </mrow> </msub> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>C</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>C</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>e</b>) <math display="inline"><semantics> <msub> <mi>Z</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>f</b>) TDR response.</p>
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<p>FoMs of <math display="inline"><semantics> <mrow> <mi>O</mi> <mi>A</mi> <mi>R</mi> <mo>@</mo> <msub> <mo>Δ</mo> <mrow> <mo>{</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>}</mo> </mrow> </msub> <mo>@</mo> <msub> <mo>Δ</mo> <mrow> <mo>{</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> <mo>}</mo> </mrow> </msub> </mrow> </semantics></math>—<math display="inline"><semantics> <msub> <mi>L</mi> <mrow> <mn>1</mn> <mo>,</mo> <mn>3</mn> </mrow> </msub> </semantics></math> (DPO phase—<math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>): (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>C</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>C</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>e</b>) <math display="inline"><semantics> <msub> <mi>Z</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>f</b>) TDR response.</p>
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<p>FoMs of <math display="inline"><semantics> <mrow> <mi>P</mi> <mi>t</mi> <mi>P</mi> <mo>@</mo> <mi mathvariant="normal">Λ</mi> </mrow> </semantics></math> - <math display="inline"><semantics> <msub> <mi>L</mi> <mrow> <mn>1</mn> <mo>,</mo> <mn>3</mn> </mrow> </msub> </semantics></math>—(DPO phase—<math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> </mrow> </semantics></math>): (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>C</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>C</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>e</b>) <math display="inline"><semantics> <msub> <mi>Z</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>f</b>) TDR response.</p>
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<p>DPO results (<span class="html-italic">k</span> = 0)—<math display="inline"><semantics> <msub> <mi>L</mi> <mrow> <mn>1</mn> <mo>,</mo> <mn>3</mn> </mrow> </msub> </semantics></math>: (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>C</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>C</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>e</b>) <math display="inline"><semantics> <msub> <mi>Z</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>f</b>) TDR response.</p>
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<p>FoMs of <math display="inline"><semantics> <mrow> <mi>O</mi> <mi>A</mi> <mi>R</mi> <mo>@</mo> <msub> <mo>Δ</mo> <mrow> <mo>{</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>}</mo> </mrow> </msub> <mo>@</mo> <msub> <mo>Δ</mo> <mrow> <mo>{</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> <mo>}</mo> </mrow> </msub> </mrow> </semantics></math>—<math display="inline"><semantics> <msub> <mi>L</mi> <mrow> <mn>1</mn> <mo>,</mo> <mn>3</mn> </mrow> </msub> </semantics></math> (DPO phase—<math display="inline"><semantics> <mrow> <mi>k</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>): (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>C</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>C</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>e</b>) <math display="inline"><semantics> <msub> <mi>Z</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>f</b>) TDR response.</p>
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<p>FoMs of <math display="inline"><semantics> <mrow> <msub> <mi>D</mi> <mrow> <mi>C</mi> <mi>t</mi> <mi>C</mi> </mrow> </msub> <mo>@</mo> <msub> <mi>D</mi> <mrow> <mi>S</mi> <mi>t</mi> <mi>i</mi> <mi>t</mi> <mi>c</mi> <mi>h</mi> </mrow> </msub> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <msub> <mo>Δ</mo> <mi>S</mi> </msub> <mo>@</mo> <mi>O</mi> <mi>A</mi> <msub> <mi>R</mi> <mi>S</mi> </msub> </mrow> </semantics></math>—<math display="inline"><semantics> <msub> <mi>L</mi> <mrow> <mn>1</mn> <mo>,</mo> <mn>3</mn> </mrow> </msub> </semantics></math> (SVO-phase results compared to the DPO output structure): (<b>a</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>D</mi> <mn>11</mn> </mrow> </msub> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>D</mi> <mi>C</mi> <mn>21</mn> </mrow> </msub> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <msub> <mi>S</mi> <mrow> <mi>C</mi> <mi>D</mi> <mn>21</mn> </mrow> </msub> </semantics></math>.</p>
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21 pages, 5698 KiB  
Article
Energy Efficiency and Throughput Maximization Using Millimeter Waves–Microwaves HetNets
by Sonain Jamil, MuhibUr Rahman, Jawad Tanveer and Amir Haider
Electronics 2022, 11(3), 474; https://doi.org/10.3390/electronics11030474 - 6 Feb 2022
Cited by 10 | Viewed by 2739
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
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<p>Smart factory scenario.</p>
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<p>Simulation scenario in MATLAB; InF: Red diamond = UE, Blue circle = Dual-Mode Base Stations.</p>
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<p>The segmentation of time slot for the <span class="html-italic">i</span>th link.</p>
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<p>Transmission between DMBS and UEs.</p>
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<p>Flowchart of OAA algorithm.</p>
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<p>The number of users vs. corresponding average throughput.</p>
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<p>The number of users vs. corresponding average energy efficiency.</p>
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<p>Selected users on mm-waves and µ waves.</p>
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<p>SINR vs Link Rate of mm-waves and µ waves.</p>
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<p>Throughput vs No. of UEs for LOS, NLOS, and HetNet.</p>
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<p>Energy Efficiency vs No. of UEs for LOS, NLOS and HetNet.</p>
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<p>Average EE of network with OAA and other algorithms.</p>
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<p>Average throughput of the network with OAA and other algorithms.</p>
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<p>Channel efficiency vs throughput of the network with OAA.</p>
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