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Electronics, Volume 9, Issue 4 (April 2020) – 47 articles

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Open AccessArticle
People Walking Classification using Automotive Radar
Electronics 2020, 9(4), 588; https://doi.org/10.3390/electronics9040588 (registering DOI) - 30 Mar 2020
Abstract
Automotive radars are able to guarantee high performances at the expenses of a relatively low cost, and recently their application has been extended to several fields in addition to the original one. In this paper we consider the use of this kind of [...] Read more.
Automotive radars are able to guarantee high performances at the expenses of a relatively low cost, and recently their application has been extended to several fields in addition to the original one. In this paper we consider the use of this kind of radars to discriminate different types of people’s movements in a real context. To this end, we exploit two different maps obtained from radar, that is, a spectrogram and a range-Doppler map. Through the application of dimensionality reduction methods, such as principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) algorithm, and the use of machine learning techniques we prove that is possible to classify with a very good precision people’s way of walking even employing commercial devices specifically designed for other purposes. Full article
(This article belongs to the Special Issue Recent Advances in Motion Analysis)
Open AccessArticle
Secure Information Transmission with Self Jamming SWIPT
Electronics 2020, 9(4), 587; https://doi.org/10.3390/electronics9040587 (registering DOI) - 30 Mar 2020
Abstract
This article is focused on implementing simultaneous wireless information and power transmission as a physical layer security measure by using artificial noise. A series of high energy precoded symbols is simultaneously transmitted along with the information symbols over a Rayleigh frequency selective fading [...] Read more.
This article is focused on implementing simultaneous wireless information and power transmission as a physical layer security measure by using artificial noise. A series of high energy precoded symbols is simultaneously transmitted along with the information symbols over a Rayleigh frequency selective fading channel. The high energy precoded symbols act as an artificial noise for the eavesdroppers. The energy symbols are precoded on the basis of a legitimate user’s channel matrix to form a null space vector, which eliminates the interference of energy symbols at the information symbol receiver antennas, while allowing the rectenna to harvest energy from the superimposed information and energy symbols. We analyze the secrecy rate and error rate performance at the receiver under different circumstances, and we show that the performance of the legitimate user can be improved by using the iterative block decision feedback equalization method at the receiver. Full article
(This article belongs to the Special Issue Cooperative Communications for Future Wireless Systems)
Open AccessArticle
Remote-State PWM with Minimum RMS Torque Ripple and Reduced Common-Mode Voltage for Three-Phase VSI-Fed BLAC Motor Drives
Electronics 2020, 9(4), 586; https://doi.org/10.3390/electronics9040586 (registering DOI) - 30 Mar 2020
Abstract
A minimum root mean square (RMS) torque ripple-remote-state pulse-width modulation (MTR-RSPWM) technique is proposed for minimizing the RMS torque ripple under reduced common-mode voltage (CMV) condition of three-phase voltage source inverters (VSI)-fed brushless alternating current (BLAC) motor drives. The q-axis current ripple due [...] Read more.
A minimum root mean square (RMS) torque ripple-remote-state pulse-width modulation (MTR-RSPWM) technique is proposed for minimizing the RMS torque ripple under reduced common-mode voltage (CMV) condition of three-phase voltage source inverters (VSI)-fed brushless alternating current (BLAC) motor drives. The q-axis current ripple due to an error voltage vector generated between the reference voltage vector and applied voltage vector is analyzed for all pulse patterns with reduced CMV of the RSPWM. From the analysis result, in the MTR-RSPWM, a sector is divided into five zones, and within each zone, pulse patterns with the lowest RMS torque ripple and reduced CMV are employed. To verify the validity of the MTR-RSPWM, theorical analysis, simulation, and experiments are performed, where the MTR-RSPWM is thoroughly compared with RSPWM3 that generates the minimum RMS current ripple. From the analytical, simulation, and experimental results, it is shown that the MTR-RSPWM significantly reduces the RMS torque ripple under a reduced CMV condition at the expense of an increase in the RMS current ripple, compared to the RSPWM3. Full article
(This article belongs to the Special Issue High Power Electric Traction Systems)
Open AccessArticle
Research on Power Quality Disturbance Detection Method Based on Improved Ensemble Empirical Mode Decomposition
Electronics 2020, 9(4), 585; https://doi.org/10.3390/electronics9040585 (registering DOI) - 30 Mar 2020
Abstract
With the increasing proportion of various unbalanced loads in the power grid, power quality is seriously challenged. It is of great significance to effectively detect, analyze, and evaluate the power quality problems. First, this paper introduces the current situation of power quality (PQ) [...] Read more.
With the increasing proportion of various unbalanced loads in the power grid, power quality is seriously challenged. It is of great significance to effectively detect, analyze, and evaluate the power quality problems. First, this paper introduces the current situation of power quality (PQ) disturbance detection methods. It summarizes that the current PQ disturbance detection methods include Wavelet Transform (WT), Hilbert–Huang Transform (HHT), and Ensemble Empirical Mode Decomposition (EEMD). EEMD has a better detection accuracy, but its running time is longer. Therefore, to reduce the running time of the EEMD algorithm, this paper proposed two improvements: increasing the screening threshold and selecting piecewise cubic Hermite interpolation polynomial fitting. At the same time, the mathematical models of transient power quality disturbance and harmonic were established for comparative verification. The experimental results showed that the improved Ensemble Empirical Mode Decomposition(IEEMD) algorithm greatly reduced the running time of the algorithm on the premise of ensuring the detection accuracy. Hence, the improvement of this paper is of great significance for the industrial application of the EEMD algorithm. Full article
(This article belongs to the Section Circuit and Signal Processing)
Open AccessFeature PaperArticle
Ultra-Compact Reconfigurable Band Reject UWB MIMO Antenna with Four Radiators
Electronics 2020, 9(4), 584; https://doi.org/10.3390/electronics9040584 (registering DOI) - 30 Mar 2020
Abstract
A compact reconfigurable UWB MIMO antenna with four radiators that accomplish on-demand band rejection from 4.9 to 6.3 GHz is presented. An LC stub is connected to the ground plane by activating the PIN diode for each radiator. Two radiators are placed perpendicular [...] Read more.
A compact reconfigurable UWB MIMO antenna with four radiators that accomplish on-demand band rejection from 4.9 to 6.3 GHz is presented. An LC stub is connected to the ground plane by activating the PIN diode for each radiator. Two radiators are placed perpendicular to each other to exploit the polarization diversity on a compact 25 × 50 mm 2 FR4 laminate. Two additional radiators are then fixed obliquely on the same laminate (without increasing size) in angular configuration at ±45 perpendicular to the first two planar radiators still exploiting polarization diversity. The design is validated by prototyping and comparing the results with the simulated ones. On demand band rejection through the use of PIN diodes, wide impedance matching (2–12 GHz), high isolation amongst the radiators, compactness achieved by angular placement of the radiators, low gain variation over the entire bandwidth, band rejection control achieved by adjusting the gap between stub and ground plane, and low TARC values makes the proposed design very suitable for commercial handheld devices (i.e., Huawei E5785 and Netgear 815S housings). The proposed configuration of the UWB MIMO radiators has been investigated first time as per authors’ knowledge. Full article
(This article belongs to the Special Issue Reconfigurable Antennas)
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Open AccessArticle
Detecting Objects from Space: An Evaluation of Deep-Learning Modern Approaches
Electronics 2020, 9(4), 583; https://doi.org/10.3390/electronics9040583 (registering DOI) - 30 Mar 2020
Abstract
Unmanned aircraft systems or drones enable us to record or capture many scenes from the bird’s-eye view and they have been fast deployed to a wide range of practical domains, i.e., agriculture, aerial photography, fast delivery and surveillance. Object detection task is one [...] Read more.
Unmanned aircraft systems or drones enable us to record or capture many scenes from the bird’s-eye view and they have been fast deployed to a wide range of practical domains, i.e., agriculture, aerial photography, fast delivery and surveillance. Object detection task is one of the core steps in understanding videos collected from the drones. However, this task is very challenging due to the unconstrained viewpoints and low resolution of captured videos. While deep-learning modern object detectors have recently achieved great success in general benchmarks, i.e., PASCAL-VOC and MS-COCO, the robustness of these detectors on aerial images captured by drones is not well studied. In this paper, we present an evaluation of state-of-the-art deep-learning detectors including Faster R-CNN (Faster Regional CNN), RFCN (Region-based Fully Convolutional Networks), SNIPER (Scale Normalization for Image Pyramids with Efficient Resampling), Single-Shot Detector (SSD), YOLO (You Only Look Once), RetinaNet, and CenterNet for the object detection in videos captured by drones. We conduct experiments on VisDrone2019 dataset which contains 96 videos with 39,988 annotated frames and provide insights into efficient object detectors for aerial images. Full article
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Open AccessArticle
Energy Efficiency-Oriented Resource Allocation for Massive MIMO Systems with Separated Channel Estimation and Feedback
Electronics 2020, 9(4), 582; https://doi.org/10.3390/electronics9040582 (registering DOI) - 30 Mar 2020
Abstract
This paper proposes a dynamic resource allocation scheme to maximize the energy efficiency (EE) for Massive MIMO Systems. The imperfect channel estimation (CE) and feedback are explicitly considered in the EE maximization problem, which aim to optimize the power allocation, the antenna subset [...] Read more.
This paper proposes a dynamic resource allocation scheme to maximize the energy efficiency (EE) for Massive MIMO Systems. The imperfect channel estimation (CE) and feedback are explicitly considered in the EE maximization problem, which aim to optimize the power allocation, the antenna subset selection for transmission, and the pilot assignment. Assuming CE error to be bounded for the complex-constrained Cramer–Rao Bound (CRB), theoretical results show that the lower bound is directly proportional to its number of unconstrained parameters. Utilizing this perspective, a separated and bi-directional estimation is developed to achieve both low CRB and low complexity by exploiting channel and noise spatial separation. Exploiting global optimization procedure, the optimal resource allocation can be transformed into a standard convex optimization problem. This allows us to derive an efficient iterative algorithm for obtaining the optimal solution. Numerical results are provided to demonstrate that the outperformance of the proposed algorithms are superior to existing schemes. Full article
(This article belongs to the Special Issue Channel Characterization for Wireless and Mobile Communications)
Open AccessFeature PaperArticle
Simulation and Experimental Validation of Novel Trajectory Planning Strategy to Reduce Vibrations and Improve Productivity of Robotic Manipulator
Electronics 2020, 9(4), 581; https://doi.org/10.3390/electronics9040581 (registering DOI) - 30 Mar 2020
Abstract
This paper aims at investigating vibrational behaviors of the industrial manipulator Racer 7-1.4, designed and manufactured by COMAU S.p.A., with the target of new trajectory planning strategies to improve productivity rate without any loss of positioning accuracy. Starting from the analysis of a [...] Read more.
This paper aims at investigating vibrational behaviors of the industrial manipulator Racer 7-1.4, designed and manufactured by COMAU S.p.A., with the target of new trajectory planning strategies to improve productivity rate without any loss of positioning accuracy. Starting from the analysis of a 9DoF multi-body system with lumped parameter, the first natural frequency of the robot was calculated in seven reference positions. Then, static and dynamic simulations were run by applying saturated ramp input and large motions to analyze the vibrational behavior of the manipulator. This research underlines that the optimal way to design the robot move is to set its duration at twice a period of free oscillation according to the first vibrational mode. Due to strong analogy of dynamic response of both 1DoF and 9DoF robot models, the closed-form solution of the 1DoF undamped system—featured by natural frequency equal to the first frequency of the 9DoF system—may be successfully adopted by the real-time trajectory planning process to predict residual vibration at move end-condition. This strategy was confirmed by experimental tests, allowing either residual vibration decrease and execution time reduction as well. Full article
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Open AccessArticle
An Accurate and Efficient Timing Prediction Framework for Wide Supply Voltage Design Based on Learning Method
Electronics 2020, 9(4), 580; https://doi.org/10.3390/electronics9040580 (registering DOI) - 30 Mar 2020
Abstract
The wide voltage design methodology has been widely employed in the state-of-the-art circuit design with the advantage of remarkable power reduction and energy efficiency enhancement. However, the timing verification issue for multiple PVT (process–voltage–temperature) corners rises due to unacceptable analysis effort increase for [...] Read more.
The wide voltage design methodology has been widely employed in the state-of-the-art circuit design with the advantage of remarkable power reduction and energy efficiency enhancement. However, the timing verification issue for multiple PVT (process–voltage–temperature) corners rises due to unacceptable analysis effort increase for multiple supply voltage nodes. Moreover, the foundry-provided timing libraries in the traditional STA (static timing analysis) approach are only available for the nominal supply voltage with limited voltage scaling, which cannot support timing verification for low voltages down to near- or sub-threshold voltages. In this paper, a learning-based approach for wide voltage design is proposed where feature engineering is performed to enhance the correlation among PVT corners based on a dilated CNN (convolutional neural network) model, and an ensemble model is utilized with two-layer stacking to improve timing prediction accuracy. The proposed method was verified with a commercial RISC (reduced instruction set computer) core under the supply voltage nodes ranging from 0.5 V to 0.9 V. Experimental results demonstrate that the prediction error is limited by 4.9% and 7.9%, respectively, within and across process corners for various working temperatures, which achieves up to 4.4× and 3.9× precision enhancement compared with related learning-based methods. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessArticle
The Experimental Modeling of Quad-Rotor Actuators with Undefined Hardware Errors for Safety-Flight
Electronics 2020, 9(4), 579; https://doi.org/10.3390/electronics9040579 (registering DOI) - 29 Mar 2020
Viewed by 165
Abstract
The speed error of actuators during the flight of a quad-rotor is included in the attitude error, and this error is immediately corrected by the pilot’s observation. As the control authority of the quad-rotor changes to a computer system, the correction of the [...] Read more.
The speed error of actuators during the flight of a quad-rotor is included in the attitude error, and this error is immediately corrected by the pilot’s observation. As the control authority of the quad-rotor changes to a computer system, the correction of the error is calculated and performed by the attitude sensor and the mathematical model of the quad-rotor. However, there is a response error to the control signal despite driving the same motor, which causes different results from the model prediction and affects the stability of the flight. Therefore, the response characteristics of hardware represented by the same mathematical model but having errors should be reflected in the modeling of the quad-rotor. In this paper, the response error of the actuators assembled with the same propellers and motors is verified through experiments. The actuators model that reflects this error is presented, and the thrust coefficient range by the propellers is also presented. Additionally, the speed error of actuators due to the voltage drop of the battery was verified through experiments, and a method for applying this error to the actuator model is presented. Full article
(This article belongs to the Section Systems & Control Engineering)
Open AccessArticle
Selective Epitaxial Growth of In Situ Doped SiGe on Bulk Ge for p+/n Junction Formation
Electronics 2020, 9(4), 578; https://doi.org/10.3390/electronics9040578 (registering DOI) - 29 Mar 2020
Viewed by 120
Abstract
Epitaxial in situ doped Si0.73Ge0.27 alloys were grown selectively on patterned bulk Ge and bulk Si wafers. Si0.73Ge0.27 layers with a surface roughness of less than 3 nm were demonstrated. Selectively grown p+Si0.73Ge [...] Read more.
Epitaxial in situ doped Si0.73Ge0.27 alloys were grown selectively on patterned bulk Ge and bulk Si wafers. Si0.73Ge0.27 layers with a surface roughness of less than 3 nm were demonstrated. Selectively grown p+Si0.73Ge0.27 layers exhibited a resistivity of 3.5 mΩcm at a dopant concentration of 2.5 × 1019 boron atoms/cm3. P+/n diodes were fabricated by selectively growing p+- Si0.73Ge0.27 on n-doped bulk Ge and n-doped Si wafers, respectively. The geometrical leakage current contribution shifts from the perimeter to the bulk as the diode sizes increase. Extracted near midgap activation energies are similar to p+/n Ge junctions formed by ion implantation. This indicates that the reverse leakage current in p+/n Ge diodes fabricated with various doping methods, could originate from the same trap-assisted mechanism. Working p+/n diodes on Ge bulk substrates displayed a reverse current density as low as 2.2·10−2 A/cm2 which was found to be comparable to other literature data. The layers developed in this work can be used as an alternative method to form p+/n junctions on Ge substrates, showing comparable junction leakage results to ion implantation approaches. Full article
(This article belongs to the Section Semiconductor Devices)
Open AccessArticle
A Novel Hybrid IDS Based on Modified NSGAII-ANN and Random Forest
Electronics 2020, 9(4), 577; https://doi.org/10.3390/electronics9040577 (registering DOI) - 29 Mar 2020
Viewed by 176
Abstract
Machine-learning techniques have received popularity in the intrusion-detection systems in recent years. Moreover, the quality of datasets plays a crucial role in the development of a proper machine-learning approach. Therefore, an appropriate feature-selection method could be considered to be an influential factor in [...] Read more.
Machine-learning techniques have received popularity in the intrusion-detection systems in recent years. Moreover, the quality of datasets plays a crucial role in the development of a proper machine-learning approach. Therefore, an appropriate feature-selection method could be considered to be an influential factor in improving the quality of datasets, which leads to high-performance intrusion-detection systems. In this paper, a hybrid multi-objective approach is proposed to detect attacks in a network efficiently. Initially, a multi-objective genetic method (NSGAII), as well as an artificial neural network (ANN), are run simultaneously to extract feature subsets. We modified the NSGAII approach maintaining the diversity control in this evolutionary algorithm. Next, a Random Forest approach, as an ensemble method, is used to evaluate the efficiency of the feature subsets. Results of the experiments show that using the proposed framework leads to better outcomes, which could be considered to be promising results compared to the solutions found in the literature. Full article
(This article belongs to the Section Artificial Intelligence)
Open AccessArticle
FQ-AGO: Fuzzy Logic Q-Learning Based Asymmetric Link Aware and Geographic Opportunistic Routing Scheme for MANETs
Electronics 2020, 9(4), 576; https://doi.org/10.3390/electronics9040576 (registering DOI) - 29 Mar 2020
Viewed by 161
Abstract
The proliferation of mobile and IoT devices, coupled with the advances in the wireless communication capabilities of these devices, have urged the need for novel communication paradigms for such heterogeneous hybrid networks. Researchers have proposed opportunistic routing as a means to leverage the [...] Read more.
The proliferation of mobile and IoT devices, coupled with the advances in the wireless communication capabilities of these devices, have urged the need for novel communication paradigms for such heterogeneous hybrid networks. Researchers have proposed opportunistic routing as a means to leverage the potentials offered by such heterogeneous networks. While several proposals for multiple opportunistic routing protocols exist, only a few have explored fuzzy logic to evaluate wireless links status in the network to construct stable and faster paths towards the destinations. We propose FQ-AGO, a novel Fuzzy Logic Q-learning Based Asymmetric Link Aware and Geographic Opportunistic Routing scheme that leverages the presence of long-range transmission links to assign forwarding candidates towards a given destination. The proposed routing scheme utilizes fuzzy logic to evaluate whether a wireless link is useful or not by capturing multiple network metrics, the available bandwidth, link quality, node transmission power, and distance progress. Based on the fuzzy logic evaluation, the proposed routing scheme employs a Q-learning algorithm to select the best candidate set toward the destination. We implemented FQ-AGO on the ns-3 simulator and compared the performance of the proposed routing scheme with three other relevant protocols: AODV, DSDV, and GOR. For precise analysis, we considered various network metrics to compare the performance of the routing protocols. The simulation result validates our analysis and demonstrates remarkable performance improvements in terms of total network throughput, packet delivery ration, and end-to-end delay. FQ-AGO achieves up to 15%, 50%, and 45% higher throughput compared to DSDV, AODV, and GOR, respectively. Meanwhile, FQ-AGO reduces by 50% the end-to-end latency and the average number of hop-count. Full article
(This article belongs to the Special Issue Wireless Network Protocols and Performance Evaluation)
Open AccessFeature PaperArticle
92.5% Average Power Efficiency Fully Integrated Floating Buck Quasi-Resonant LED Drivers Using GaN FETs
Electronics 2020, 9(4), 575; https://doi.org/10.3390/electronics9040575 (registering DOI) - 29 Mar 2020
Viewed by 169
Abstract
LEDs are highly energy efficient and have substantially longer lifetimes compared to other existing lighting technologies. In order to facilitate the new generation of LED devices, approaches to improve power efficiency with increased integration level for lighting device should be analysed. This paper [...] Read more.
LEDs are highly energy efficient and have substantially longer lifetimes compared to other existing lighting technologies. In order to facilitate the new generation of LED devices, approaches to improve power efficiency with increased integration level for lighting device should be analysed. This paper proposes a fully on-chip integrated LED driver design implemented using heterogeneous integration of gallium nitride (GaN) devices atop BCD circuits. The performance of the proposed design is then compared with the conventional fully on-board integration of power devices with the LED driver integrated circuit (IC). The experimental results confirm that the fully on-chip integrated LED driver achieves a consistently higher power efficiency value compared with the fully on-board design within the input voltage range of 4.5–5.5 V. The maximal percentage improvement in the efficiency of the on-chip solution compared with the on-board solution is 18%. Full article
(This article belongs to the Special Issue Nitride Semiconductors Revolution: Material, Devices and Applications)
Open AccessArticle
An AMOLED Pixel Circuit Based on LTPS Thin-film Transistors with Mono-Type Scanning Driving
Electronics 2020, 9(4), 574; https://doi.org/10.3390/electronics9040574 (registering DOI) - 28 Mar 2020
Viewed by 179
Abstract
Using low-temperature poly-silicon thin-film transistors (LTPS TFTs) as a basis, a pixel circuit for an active matrix organic light-emitting diode (AMOLED) with narrow bezel displays was developed. The pixel circuit features mono-type scanning signals, elimination of static power lines, and pixel-integrated emitting control [...] Read more.
Using low-temperature poly-silicon thin-film transistors (LTPS TFTs) as a basis, a pixel circuit for an active matrix organic light-emitting diode (AMOLED) with narrow bezel displays was developed. The pixel circuit features mono-type scanning signals, elimination of static power lines, and pixel-integrated emitting control functions. Therefore, gate driver circuits of the display bezel can be simplified efficiently. In addition, the pixel circuit has a high-resolution design due to an increase of the pulse width of the scan signal to extend the threshold voltage and internal–resistance drop (IR drop) detection period. Further, regarding the influences of process–voltage–temperature (PVT) variation in the pixel circuit, comparison investigations were carried out with the proposed circuit and other pixel circuits with mono-type scanning signals using Monte Carlo analysis. The feasibility of the proposed pixel circuit is well demonstrated, as the current variations can be reduced to 2.1% for the supplied power reduced from 5 V to 3 V due to IR drop, and the current variation is as low as 10.6% with operating temperatures from –40 degrees to 85 degrees. Full article
(This article belongs to the Special Issue Advanced Integrated Circuits Technology)
Open AccessFeature PaperArticle
Design of a Cyberattack Resilient 77 GHz Automotive Radar Sensor
Electronics 2020, 9(4), 573; https://doi.org/10.3390/electronics9040573 (registering DOI) - 28 Mar 2020
Viewed by 241
Abstract
In this paper, we propose a novel 77 GHz automotive radar sensor, and demonstrate its cyberattack resilience using real measurements. The proposed system is built upon a standard Frequency Modulated Continuous Wave (FMCW) radar RF-front end, and the novelty is in the DSP [...] Read more.
In this paper, we propose a novel 77 GHz automotive radar sensor, and demonstrate its cyberattack resilience using real measurements. The proposed system is built upon a standard Frequency Modulated Continuous Wave (FMCW) radar RF-front end, and the novelty is in the DSP algorithm used at the firmware level. All attack scenarios are based on real radar signals generated by Texas Instruments AWR series 77 GHz radars, and all measurements are done using the same radar family. For sensor networks, including interconnected autonomous vehicles sharing radar measurements, cyberattacks at the network/communication layer is a known critical problem, and has been addressed by several different researchers. What is addressed in this paper is cyberattacks at the physical layer, that is, adversarial agents generating 77 GHz electromagnetic waves which may cause a false target detection, false distance/velocity estimation, or not detecting an existing target. The main algorithm proposed in this paper is not a predictive filtering based cyberattack detection scheme where an “unusual” difference between measured and predicted values triggers an alarm. The core idea is based on a kind of physical challenge-response authentication, and its integration into the radar DSP firmware. Full article
(This article belongs to the Section Microwave and Wireless Communications)
Open AccessArticle
A User-Friendly Verification Approach for IEC 61131-3 PLC Programs
Electronics 2020, 9(4), 572; https://doi.org/10.3390/electronics9040572 (registering DOI) - 28 Mar 2020
Viewed by 179
Abstract
Programmable logic controllers (PLCs) are special embedded computers that are widely used in industrial control systems. To ensure the safety of industrial control systems, it is necessary to verify the correctness of PLCs. Formal verification is considered to be an effective method to [...] Read more.
Programmable logic controllers (PLCs) are special embedded computers that are widely used in industrial control systems. To ensure the safety of industrial control systems, it is necessary to verify the correctness of PLCs. Formal verification is considered to be an effective method to verify whether a PLC program conforms to its specifications, but the expertise requirements and the complexity make it hard to be mastered and widely applied. In this paper, we present a specification-mining-based verification approach for IEC 61131-3 PLC programs. It only requires users to review specifications mined from the program behaviors instead of model checking for specified specifications, which can greatly improve the efficiency of safety verification and is much easier for control system engineers to use. Moreover, we implement a proof-of-concept tool named PLCInspector that supports directly mining LTL specifications and data invariants from PLC programs. Two examples and one real-life case study are presented to illustrate its practicability and efficiency. In addition, a comparison with the existing verification approaches for PLC programs is discussed. Full article
(This article belongs to the Special Issue Software Verification and Validation for Embedded Systems)
Open AccessFeature PaperArticle
Hardware in the Loop Implementation of the Oscillator-based Heart Model: a Framework for Testing Medical Devices
Electronics 2020, 9(4), 571; https://doi.org/10.3390/electronics9040571 (registering DOI) - 28 Mar 2020
Viewed by 187
Abstract
The hardware in the loop technologies allow to simulate physical models in combination with real devices in order to validate the behavior of the latter under different conditions, not easily reproducible in the real world. They are widely used in various industrial applications. [...] Read more.
The hardware in the loop technologies allow to simulate physical models in combination with real devices in order to validate the behavior of the latter under different conditions, not easily reproducible in the real world. They are widely used in various industrial applications. In this work we want to extend the methodology to medical devices. These must interact with the patient to obtain the desired clinical result, however, during the development and validation phase of medical devices, the patient cannot be involved in the testing process. In this article the hardware in the loop methodology is proposed starting from a mathematical model of the heart, based on oscillators, that can be used to validate pacemakers or other medical devices. Full article
Open AccessFeature PaperArticle
Building a Better Baseline for Residential Demand Response Programs: Mitigating the Effects of Customer Heterogeneity and Random Variations
Electronics 2020, 9(4), 570; https://doi.org/10.3390/electronics9040570 (registering DOI) - 28 Mar 2020
Viewed by 209
Abstract
Peak-time rebates offer an opportunity to introduce demand response in electricity markets. To implement peak-time rebates, utilities must accurately determine the consumption level if the program were not in effect. Reliable calculations of customer baseline load elude utilities and independent system operators, due [...] Read more.
Peak-time rebates offer an opportunity to introduce demand response in electricity markets. To implement peak-time rebates, utilities must accurately determine the consumption level if the program were not in effect. Reliable calculations of customer baseline load elude utilities and independent system operators, due to factors that include heterogeneous demands and random variations. Prevailing research is limited for residential markets, which are growing rapidly with the presence of load aggregators and the availability of smart grid systems. Our research pioneers a novel method that clusters customers according to the size and predictability of their demands, substantially improving existing customer baseline calculations and other clustering methods. Full article
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Open AccessArticle
Fault Current Limiting Characteristics of a Small-Scale Bridge Type SFCL with Single HTSC Element Using Flux-Coupling
Electronics 2020, 9(4), 569; https://doi.org/10.3390/electronics9040569 (registering DOI) - 28 Mar 2020
Viewed by 153
Abstract
In this paper, a bridge type superconducting fault current limiter (SFCL) with a single high-temperature superconducting (HTSC) element is proposed to allow fault current limiting operation in direct current (DC) conditions. First, the principle of operation of the bridge type SFCL with a [...] Read more.
In this paper, a bridge type superconducting fault current limiter (SFCL) with a single high-temperature superconducting (HTSC) element is proposed to allow fault current limiting operation in direct current (DC) conditions. First, the principle of operation of the bridge type SFCL with a single HTSC element using flux-coupling was presented. After the fault occurrence, the fault current limiting operation and voltage characteristics, the power load characteristics of each device, and the energy consumption of the two coils and the HTSC element were analyzed in the proposed SFCL. As a result, it is confirmed that in the case of the additive polarity winding, the power consumption and the energy consumption of the HTSC element were lower than those in the subtractive polarity winding, and the fault current limiting characteristics were excellent. Full article
(This article belongs to the Special Issue Advanced Energy Systems with Superconductivity)
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Open AccessArticle
Learning Effective Skeletal Representations on RGB Video for Fine-Grained Human Action Quality Assessment
Electronics 2020, 9(4), 568; https://doi.org/10.3390/electronics9040568 (registering DOI) - 28 Mar 2020
Viewed by 167
Abstract
In this paper, we propose an integrated action classification and regression learning framework for the fine-grained human action quality assessment of RGB videos. On the basis of 2D skeleton data obtained per frame of RGB video sequences, we present an effective representation of [...] Read more.
In this paper, we propose an integrated action classification and regression learning framework for the fine-grained human action quality assessment of RGB videos. On the basis of 2D skeleton data obtained per frame of RGB video sequences, we present an effective representation of joint trajectories to train action classifiers and a class-specific regression model for a fine-grained assessment of the quality of human actions. To manage the challenge of view changes due to camera motion, we develop a self-similarity feature descriptor extracted from joint trajectories and a joint displacement sequence to represent dynamic patterns of the movement and posture of the human body. To weigh the impact of joints for different action categories, a class-specific regression model is developed to obtain effective fine-grained assessment functions. In the testing stage, with the supervision of the action classifier’s output, the regression model of a specific action category is selected to assess the quality of skeleton motion extracted from the action video. We take advantage of the discrimination of the action classifier and the viewpoint invariance of the self-similarity feature to boost the performance of the learning-based quality assessment method in a realistic scene. We evaluate our proposed method using diving and figure skating videos of the publicly available MIT Olympic Scoring dataset, and gymnastic vaulting videos of the recent benchmark University of Nevada Las Vegas (UNLV) Olympic Scoring dataset. The experimental results show that the proposed method achieved an improved performance, which is measured by the mean rank correlation coefficient between the predicted regression scores and the ground truths. Full article
(This article belongs to the Special Issue Intelligent Electronic Devices)
Open AccessArticle
Analysis of HMAX Algorithm on Black Bar Image Dataset
Electronics 2020, 9(4), 567; https://doi.org/10.3390/electronics9040567 (registering DOI) - 28 Mar 2020
Viewed by 161
Abstract
An accurate detection and classification of scenes and objects is essential for interacting with the world, both for living beings and for artificial systems. To reproduce this ability, which is so effective in the animal world, numerous computational models have been proposed, frequently [...] Read more.
An accurate detection and classification of scenes and objects is essential for interacting with the world, both for living beings and for artificial systems. To reproduce this ability, which is so effective in the animal world, numerous computational models have been proposed, frequently based on bioinspired, computational structures. Among these, Hierarchical Max-pooling (HMAX) is probably one of the most important models. HMAX is a recognition model, mimicking the structures and functions of the primate visual cortex. HMAX has already proven its effectiveness and versatility. Nevertheless, its computational structure presents some criticalities, whose impact on the results has never been systematically assessed. Traditional assessments based on photographs force to choose a specific context; the complexity of images makes it difficult to analyze the computational structure. Here we present a new, general and unspecific assessment of HMAX, introducing the Black Bar Image Dataset, a customizable set of images created to be a universal and flexible model of any ‘real’ image. Results: surprisingly, HMAX demonstrates a notable sensitivity also with a low contrast of luminance. Images containing a wider information pattern enhance the performances. The presence of textures improves performance, but only if the parameterization of the Gabor filter allows its correct encoding. In addition, in complex conditions, HMAX demonstrates good effectiveness in classification. Moreover, the present assessment demonstrates the benefits offered by the Black Bar Image Dataset, its modularity and scalability, for the functional investigations of any computational models. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessArticle
Iron Loss Minimization Strategy for Predictive Torque Control of Induction Motor
Electronics 2020, 9(4), 566; https://doi.org/10.3390/electronics9040566 (registering DOI) - 28 Mar 2020
Viewed by 196
Abstract
Today’s modern control strategies of an induction motor (IM) drive require a power source with an adjustable output voltage frequency and amplitude. The most commonly used converter topology is a two-level voltage-source inverter (VSI). However, the utilization of a VSI introduces additional voltage [...] Read more.
Today’s modern control strategies of an induction motor (IM) drive require a power source with an adjustable output voltage frequency and amplitude. The most commonly used converter topology is a two-level voltage-source inverter (VSI). However, the utilization of a VSI introduces additional voltage and current distortion, which leads to additional power losses in the machine’s magnetic circuit. Both the transistor switching frequency and the type of the inverter control determine the total harmonic distortion (THD) of the motor’s phase currents. In this paper, the influence of the inverter DC-link voltage on the iron losses of an IM controlled by a predictive torque control (PTC) is presented. It is shown that if the IM drive operates below the rated speed, it is possible to modify the PTC algorithm to reduce the additional iron losses caused by the non-harmonic inverter output voltage. The control of the DC-link voltage is achieved by using a silicon-controlled rectifier. Experiments were conducted on a 5.5 kW IM controlled by PTC, and the results are compared against a sinusoidal voltage supply created by a synchronous generator. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
Accurate Closed-Form Solution for Moving Underwater Vehicle Localization Using Two-Way Travel Time
Electronics 2020, 9(4), 565; https://doi.org/10.3390/electronics9040565 (registering DOI) - 28 Mar 2020
Viewed by 174
Abstract
Position information is essential for an underwater vehicle that can affect the performance of many other applications. Vehicle motion during the two-way travel time (TWTT) using an acoustic positioning system can affect the localization accuracy of the estimators based on the traditional static [...] Read more.
Position information is essential for an underwater vehicle that can affect the performance of many other applications. Vehicle motion during the two-way travel time (TWTT) using an acoustic positioning system can affect the localization accuracy of the estimators based on the traditional static model. A new time measurement model for moving vehicle localization is presented, which compensates for the vehicle motion. The Cramér–Rao lower bounds (CRLBs) of the proposed model are derived for two different cases, where the depth of the underwater vehicle is unknown or known. Then, closed-form solutions for the two cases using the proposed model are derived and the solutions are shown analytically to reach the CRLBs. Simulations collaborate the theoretical performance of the proposed estimators and the moving model significantly improves the localization accuracy in comparison with the static model. Full article
(This article belongs to the Section Electrical and Autonomous Vehicles)
Open AccessArticle
Sustainable IoT Sensing Applications Development through GraphQL-Based Abstraction Layer
Electronics 2020, 9(4), 564; https://doi.org/10.3390/electronics9040564 (registering DOI) - 28 Mar 2020
Viewed by 225
Abstract
Internet of Things (IoT) networks are mostly comprised of power-constrained devices, therefore the most important consideration in designing IoT applications, based on sensor networks is energy efficiency. Minor improvement in energy conservation methods can lead to a significant increase in the lifetime of [...] Read more.
Internet of Things (IoT) networks are mostly comprised of power-constrained devices, therefore the most important consideration in designing IoT applications, based on sensor networks is energy efficiency. Minor improvement in energy conservation methods can lead to a significant increase in the lifetime of IoT devices and overall network. To achieve efficient utilisation of energy, different solutions are proposed such as duty cycling optimization, design changes at the MAC layer, etc. In this paper, we propose a new approach to overcome this challenge in cloud-based IoT sensing applications, based on integration of an abstraction layer with constrained application mechanism. To achieve energy conservation and efficient data management in IoT sensing applications, we incorporate modules of efficient web framework with cloud services, in order to minimize the number of round trips for data delivery and graph-based data representation. Our study is the first attempt in the literature, to the best of our knowledge, which introduces the potential of this integration for achieving the aforementioned objectives in the target applications. We implemented the proposed interfacing of abstraction layer in constrained applications, to develop a testbed using Z1 IoT motes, Contiki OS and GraphQL web framework with Google cloud services. Experimental comparisons against baseline REST architecture approach show that our proposed approach achieved significant reductions in data delivery delay and energy consumption (minimum 51.53% and 52.88%, respectively) in IoT applications involving sensor network. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessFeature PaperArticle
10-GHz Fully Differential Sallen–Key Lowpass Biquad Filters in 55nm SiGe BiCMOS Technology
Electronics 2020, 9(4), 563; https://doi.org/10.3390/electronics9040563 (registering DOI) - 28 Mar 2020
Viewed by 192
Abstract
Multi-GHz lowpass filters are key components for many RF applications and are required for the implementation of integrated high-speed analog-to-digital and digital-to-analog converters and optical communication systems. In the last two decades, integrated filters in the Multi-GHz range have been implemented using III-V [...] Read more.
Multi-GHz lowpass filters are key components for many RF applications and are required for the implementation of integrated high-speed analog-to-digital and digital-to-analog converters and optical communication systems. In the last two decades, integrated filters in the Multi-GHz range have been implemented using III-V or SiGe technologies. In all cases in which the size of passive components is a concern, inductorless designs are preferred. Furthermore, due to the recent development of high-speed and high-resolution data converters, highly linear multi-GHz filters are required more and more. Classical open loop topologies are not able to achieve high linearity, and closed loop filters are preferred in all applications where linearity is a key requirement. In this work, we present a fully differential BiCMOS implementation of the classical Sallen Key filter, which is able to operate up to about 10 GHz by exploiting both the bipolar and MOS transistors of a commercial 55-nm BiCMOS technology. The layout of the biquad filter has been implemented, and the results of post-layout simulations are reported. The biquad stage exhibits excellent SFDR (64 dB) and dynamic range (about 50 dB) due to the closed loop operation, and good power efficiency (0.94 pW/Hz/pole) with respect to comparable active inductorless lowpass filters reported in the literature. Moreover, unlike other filters, it exploits the different active devices offered by commercial SiGe BiCMOS technologies. Parametric and Monte Carlo simulations are also included to assess the robustness of the proposed biquad filter against PVT and mismatch variations. Full article
(This article belongs to the Special Issue Filter Design Solutions for RF systems)
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Open AccessFeature PaperArticle
A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
Electronics 2020, 9(4), 562; https://doi.org/10.3390/electronics9040562 (registering DOI) - 27 Mar 2020
Viewed by 187
Abstract
A reconfigurable CMOS inverter-based stacked power amplifier (PA) is proposed to extend impedance coverage, while maintaining an output power exceeding the specific power level under the worst antenna impedance mismatch conditions. The adopted process technology supports multi-threshold metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and [...] Read more.
A reconfigurable CMOS inverter-based stacked power amplifier (PA) is proposed to extend impedance coverage, while maintaining an output power exceeding the specific power level under the worst antenna impedance mismatch conditions. The adopted process technology supports multi-threshold metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and therefore, the proposed PA employs high threshold voltage (Vth) MOSFETs to increase the output voltage swing, and the output power under a given load condition. The unit cell of the last PA stage relies on a cascode inverter that is implemented by adding cascode transistors to the traditional inverter amplifier. By stacking two identical cascode inverters, and enabling one or both of them through digital switch control, the proposed PA can control the maximum output voltage swing and change the optimum load Ropt, resulting in maximum output power with peak power added efficiency (PAE). The cascode transistors mitigate breakdown issues when the upper cascode inverter stage is driven by a supply voltage of 2×VDD, and decrease the output impedance of the PA by changing its operation mode from the saturation region to the linear region. This variable output impedance characteristic is useful in extending the impedance coverage of the proposed PA. The reconfigurable PA supports three operation modes: cascode inverter configuration (CIC), double-stacked cascode inverter configuration (DSCIC) and double-stacked inverter configuration (DSIC). These show Ropt of around 100, 50 and 25 Ω, respectively. In the simulation results, the proposed PA operating under the three configurations showed a saturated output power (Psat) of +6.1 dBm and a peak PAE of 41.1% under a 100 Ω load impedance condition, a Psat of +4.5 dBm and a peak PAE of 44.3% under a 50 Ω load impedance condition, and a Psat of +5.2 dBm and a peak PAE of 37.1% under a 25 Ω load impedance condition, respectively. Compared to conventional inverter-based PAs, the proposed design significantly extends impedance coverage, while maintaining an output power exceeding the specific power level, without sacrificing power efficiency using only hardware reconfiguration. Full article
(This article belongs to the Special Issue CMOS Power Amplifier Design and Applications)
Open AccessFeature PaperArticle
Inversion-Based Approach for Detection and Isolation of Faults in Switched Linear Systems
Electronics 2020, 9(4), 561; https://doi.org/10.3390/electronics9040561 (registering DOI) - 27 Mar 2020
Viewed by 184
Abstract
This paper addresses the problem of the left inversion of switched linear systems from a diagnostics perspective. The problem of left inversion is to reconstruct the input of a system with the knowledge of its output, whose differentiation is usually required. In the [...] Read more.
This paper addresses the problem of the left inversion of switched linear systems from a diagnostics perspective. The problem of left inversion is to reconstruct the input of a system with the knowledge of its output, whose differentiation is usually required. In the case of this work, the objective is to reconstruct the system’s unknown inputs, based on the knowledge of its outputs, switching sequence and known inputs. With the inverse model of the switched linear system, a real-time Fault Detection and Isolation (FDI) algorithm with an integrated Fuzzy Logic System (FLS) that is capable of detecting and isolating abrupt faults occurring in the system is developed. In order to attenuate the effects of unknown disturbances and noise at the output of the inverse model, a smoothing strategy is also used. The results are illustrated with an example. The performance of the method is validated experimentally in a DC-DC boost converter, using a low-cost microcontroller, without any additional components. Full article
(This article belongs to the Section Power Electronics)
Open AccessFeature PaperArticle
OLIMP: A Heterogeneous Multimodal Dataset for Advanced Environment Perception
Electronics 2020, 9(4), 560; https://doi.org/10.3390/electronics9040560 (registering DOI) - 27 Mar 2020
Viewed by 202
Abstract
A reliable environment perception is a crucial task for autonomous driving, especially in dense traffic areas. Recent improvements and breakthroughs in scene understanding for intelligent transportation systems are mainly based on deep learning and the fusion of different modalities. In this context, we [...] Read more.
A reliable environment perception is a crucial task for autonomous driving, especially in dense traffic areas. Recent improvements and breakthroughs in scene understanding for intelligent transportation systems are mainly based on deep learning and the fusion of different modalities. In this context, we introduce OLIMP: A heterOgeneous Multimodal Dataset for Advanced EnvIronMent Perception. This is the first public, multimodal and synchronized dataset that includes UWB radar data, acoustic data, narrow-band radar data and images. OLIMP comprises 407 scenes and 47,354 synchronized frames, presenting four categories: pedestrian, cyclist, car and tram. The dataset includes various challenges related to dense urban traffic such as cluttered environment and different weather conditions. To demonstrate the usefulness of the introduced dataset, we propose a fusion framework that combines the four modalities for multi object detection. The obtained results are promising and spur for future research. Full article
(This article belongs to the Special Issue Face Recognition and Its Applications)
Open AccessArticle
Inverse Design of Artificial Materials based Lens Antennas Through the Scattering Matrix Method
Electronics 2020, 9(4), 559; https://doi.org/10.3390/electronics9040559 (registering DOI) - 27 Mar 2020
Viewed by 165
Abstract
The design of spatially varying lens antennas based on artificial materials is of high interest for their wide range of applicability. In this paper, we propose a novel design procedure relying on an inverse formulation of the scattering matrix method (SMM). Differently from [...] Read more.
The design of spatially varying lens antennas based on artificial materials is of high interest for their wide range of applicability. In this paper, we propose a novel design procedure relying on an inverse formulation of the scattering matrix method (SMM). Differently from many adopted approaches, which resort to global optimizations or homogenization procedures, the inverse SMM (I-SMM) allows the synthesis of optimal parameters (geometrical and/or electromagnetic) for the inclusions realizing the overall device in a very effective manner. With reference to the 2D TM case, the proposed tool has been successfully assessed through the synthesis of different kinds of lenses radiating a pencil beam. Full article
(This article belongs to the Special Issue Electromagnetic Scattering Theory and Its Applications)
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