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Electronics, Volume 9, Issue 8 (August 2020) – 152 articles

Cover Story (view full-size image): Road safety and vehicle efficiency are key factors for the development of autonomous vehicles. Thus, this industry needs to know the exact location of the vehicle on the road to safely perform autonomous maneuvers, even in scenarios where GNSS technology is not reliable enough. This leads to the use of a combination of technologies to achieve this ambitious target. UWB is a potential candidate to be employed as a redundant precise positioning system. This technology, mainly used in indoor environments, needs to be exploited by fusing the UWB ranging estimations with inertial and odometry data from the on-board sensors of the vehicle. The integration of this approach can provide highly accurate positioning data to the autonomous vehicles and continuous knowledge of the vehicle’s location as is required to perform an autonomous maneuver. View this paper.
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20 pages, 1659 KiB  
Article
Malvertising in Facebook: Analysis, Quantification and Solution
by Aritz Arrate, José González-Cabañas, Ángel Cuevas and Rubén Cuevas
Electronics 2020, 9(8), 1332; https://doi.org/10.3390/electronics9081332 - 18 Aug 2020
Cited by 1 | Viewed by 4095
Abstract
Online advertising is a wealthy industry that generated more than $100B in 2018 only in the US and delivers billions of ads to Internet users every day with. These impressive numbers have also attracted the attention of malicious players that try to exploit [...] Read more.
Online advertising is a wealthy industry that generated more than $100B in 2018 only in the US and delivers billions of ads to Internet users every day with. These impressive numbers have also attracted the attention of malicious players that try to exploit the online advertising ecosystem for their own benefit. In particular, one of the most harmful practices refers to malicious users that act as advertisers to deliver unsafe ads. The goal of these ads is to compromise the security of the users that receive those ads. This practice is referred to as Malvertising. Some reports have estimated the economic loss caused by malvertising to the online advertising sector to $1.1B in 2017. This paper is the first work that analyses and quantifies the impact of malvertising in Facebook. To accomplish this study, we rely on a dataset that includes more than 5 M ads delivered to 3 K Facebook users from 126 K advertisers between October 2016 and May 2018. Our results reveal that although the portion of advertisers (0.68%) and ads (0.17%) associated to malvertising is very low, 1/3 of the users in our study were exposed to malvertising. Finally, we also propose a novel solution to block malvertising ads in real-time in Facebook. Full article
(This article belongs to the Section Computer Science & Engineering)
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29 pages, 3498 KiB  
Article
Design of True Time Delay Millimeter Wave Beamformers for 5G Multibeam Phased Arrays
by Dimitrios I. Lialios, Nikolaos Ntetsikas, Konstantinos D. Paschaloudis, Constantinos L. Zekios, Stavros V. Georgakopoulos and George A. Kyriacou
Electronics 2020, 9(8), 1331; https://doi.org/10.3390/electronics9081331 - 18 Aug 2020
Cited by 31 | Viewed by 6145
Abstract
Millimeter wave (mm-Wave) technology is likely the key enabler of 5G and early 6G wireless systems. The high throughput, high capacity, and low latency that can be achieved, when mm-Waves are utilized, makes them the most promising backhaul as well as fronthaul solutions [...] Read more.
Millimeter wave (mm-Wave) technology is likely the key enabler of 5G and early 6G wireless systems. The high throughput, high capacity, and low latency that can be achieved, when mm-Waves are utilized, makes them the most promising backhaul as well as fronthaul solutions for the communication between small cells and base stations or between base stations and the gateway. Depending on the channel properties different communication systems (e.g., beamforming and MIMO) can accordingly offer the best solution. In this work, our goal is to design millimeter wave beamformers for switched beam phased arrays as hybrid beamforming stages. Specifically, three different analog beamforming techniques for the frequency range of 27–33 GHz are presented. First, a novel compact multilayer Blass matrix is proposed. Second, a modified dummy-ports free, highly efficient Rotman lens is introduced. Finally, a three-layer true-time-delay tree topology inspired by microwave photonics is presented. Full article
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10 pages, 1062 KiB  
Article
Non-Orthogonal Multiple Access in Multiuser MIMO Configurations via Code Reuse and Principal Component Analysis
by Panagiotis K. Gkonis, Panagiotis T. Trakadas and Lambros E. Sarakis
Electronics 2020, 9(8), 1330; https://doi.org/10.3390/electronics9081330 - 18 Aug 2020
Cited by 8 | Viewed by 2240
Abstract
The goal of the study presented in this paper is to evaluate the performance of a proposed transmission scheme in multiuser multiple-input multiple-output (MIMO) configurations, via code reuse. Hence, non-orthogonal multiple access (NOMA) is performed. To this end, a correlation matrix of the [...] Read more.
The goal of the study presented in this paper is to evaluate the performance of a proposed transmission scheme in multiuser multiple-input multiple-output (MIMO) configurations, via code reuse. Hence, non-orthogonal multiple access (NOMA) is performed. To this end, a correlation matrix of the received data is constructed at the transmitter, with feedback as only the primary eigenvector of the equivalent channel matrix, which is derived after principal component analysis (PCA) at the receiver. Afterwards, users experiencing improved channel quality (i.e., diagonal terms of the correlation matrix) along with reduced multiple access interference (i.e., the inner product of transmission vectors) are the potential candidates for their assigned code to be reused. As the results indicate, considering various MIMO configurations, the proposed approach can achieve almost 33% code assignment gain (CAG), when successive interference cancellation (SIC) is employed in mobile receivers. However, even in the absence of SIC, CAG is still maintained with a tolerable average bit error rate (BER) degradation. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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14 pages, 3509 KiB  
Article
Design of an Ultra-Wideband Microstrip-to-Slotline Transition on Low-Permittivity Substrate
by Jung Seok Lee, Gwan Hui Lee, Wahab Mohyuddin, Hyun Chul Choi and Kang Wook Kim
Electronics 2020, 9(8), 1329; https://doi.org/10.3390/electronics9081329 - 17 Aug 2020
Cited by 4 | Viewed by 5225
Abstract
Analysis and design of an ultra-wideband microstrip-to-slotline transition on a low permittivity substrate is presented. Cross-sectional structures along the proposed transition are analyzed using conformal mapping assuming quasi-TEM modes, attaining one analytical line impedance formula with varying design parameters. Although the slotline is [...] Read more.
Analysis and design of an ultra-wideband microstrip-to-slotline transition on a low permittivity substrate is presented. Cross-sectional structures along the proposed transition are analyzed using conformal mapping assuming quasi-TEM modes, attaining one analytical line impedance formula with varying design parameters. Although the slotline is a non-TEM transmission line, the transitional structures are configured to have quasi-TEM modes before forming into the slotline. The line impedance is optimally tapered using the Klopfenstein taper, and the electric field shapes are smoothly transformed from microstrip line to slotline. The analytical formula is accurate within 5% difference, and the final transition configuration can be designed without parameter tuning. The implemented microstrip-to-slotline transition possesses insertion loss of less than 1.5 dB per transition and return loss of more than 10 dB from 4.4 to over 40 GHz. Full article
(This article belongs to the Special Issue Ultra-Wideband Microwave/MM-Wave Components and Packaging)
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23 pages, 1867 KiB  
Article
NOVA Mobility Assistive System: Developed and Remotely Controlled with IOPT-Tools
by Filipe Moutinho, Rogerio Campos-Rebelo, Carolina Lagartinho-Oliveira, Edna Moreira, Bruno Almeida and Luis Gomes
Electronics 2020, 9(8), 1328; https://doi.org/10.3390/electronics9081328 - 17 Aug 2020
Cited by 1 | Viewed by 2519
Abstract
In this paper, a Mobility Assistive System (NOVA-MAS) and a model-driven development approach are proposed to support the acquisition and analysis of data, infrastructures control, and dissemination of information along public roads. A literature review showed that the work related to mobility assistance [...] Read more.
In this paper, a Mobility Assistive System (NOVA-MAS) and a model-driven development approach are proposed to support the acquisition and analysis of data, infrastructures control, and dissemination of information along public roads. A literature review showed that the work related to mobility assistance of pedestrians in wheelchairs has a gap in ensuring their safety on road. The problem is that pedestrians in wheelchairs and scooters often do not enjoy adequate and safe lanes for their circulation on public roads, having to travel sometimes side by side with vehicles and cars moving at high speed. With NOVA-MAS, city infrastructures can obtain information regarding the environment and provide it to their users/vehicles, increasing road safety in an inclusive way, contributing to the decrease of the accidents of pedestrians in wheelchairs. NOVA-MAS not only supports information dissemination, but also data acquisition from sensors and infrastructures control, such as traffic light signs. For that, it proposed a development approach that supports the acquisition of data from the environment and its control while using a tool framework, named IOPT-Tools (Input-Output Place-Transition Tools). IOPT-Tools support controllers’ specification, validation, and implementation, with remote operation capabilities. The infrastructures’ controllers are specified through IOPT Petri net models, which are then simulated using computational tools and verified using state-space-based model-checking tools. In addition, an automatic code generator tool generates the C code, which supports the controllers’ implementation, avoiding manual codification errors. A set of prototypes were developed and tested to validate and conclude on the feasibility of the proposals. Full article
(This article belongs to the Section Systems & Control Engineering)
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16 pages, 11675 KiB  
Article
A Ku-Band GaAs Multifunction Transmitter and Receiver Chipset
by Hyunkyu Lee, Younghwan Kim, Iljin Lee, Dongkyo Kim, Kwangwon Park and Sanggeun Jeon
Electronics 2020, 9(8), 1327; https://doi.org/10.3390/electronics9081327 - 17 Aug 2020
Cited by 12 | Viewed by 3563
Abstract
This paper presents a Ku-band monolithic multifunction transmitter and receiver chipset fabricated in 0.25-μm GaAs pseudomorphic high-electron mobility transistor technology. The chipset achieves a high level of integration, including a 4-bit 360° digital phase shifter, 5-bit 15.5-dB digital attenuator, amplifier and 9-bit digital [...] Read more.
This paper presents a Ku-band monolithic multifunction transmitter and receiver chipset fabricated in 0.25-μm GaAs pseudomorphic high-electron mobility transistor technology. The chipset achieves a high level of integration, including a 4-bit 360° digital phase shifter, 5-bit 15.5-dB digital attenuator, amplifier and 9-bit digital serial-to-parallel converter for digital circuit control. Since the multifunction chipset includes a medium power amplifier and a low-noise amplifier, it features high P1dB and low noise figures over the full Ku-band frequencies. The multifunction transmitter shows a peak gain of 16.5 dB with output P1dB of 19.2 dBm at 15 GHz. The multifunction receiver shows a peak gain of 17.3 dB with noise figure of 2.5 dB at 15 GHz. The attenuation range is 15.5 dB with a step of 0.5 dB and the phase shift range is 360° with a step of 22.5°. Each chip area of the transmitter and receiver is 4.2 × 2.8 mm2. Full article
(This article belongs to the Section Microelectronics)
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15 pages, 3218 KiB  
Article
An RSSI-Based Localization, Path Planning and Computer Vision-Based Decision Making Robotic System
by Jatin Upadhyay, Abhishek Rawat, Dipankar Deb, Vlad Muresan and Mihaela-Ligia Unguresan
Electronics 2020, 9(8), 1326; https://doi.org/10.3390/electronics9081326 - 17 Aug 2020
Cited by 8 | Viewed by 4399
Abstract
A robotic navigation system operates flawlessly under an adequate GPS signal range, whereas indoor navigation systems use the simultaneous localization and mapping system or other vision-based localization systems. The sensor used in indoor navigation systems is not suitable for low power and small [...] Read more.
A robotic navigation system operates flawlessly under an adequate GPS signal range, whereas indoor navigation systems use the simultaneous localization and mapping system or other vision-based localization systems. The sensor used in indoor navigation systems is not suitable for low power and small scale robotic systems. The wireless area network transmitting devices have fixed transmission power, and the receivers get the different values of signal strength based on their surrounding environments. In the proposed method, the received signal strength index (RSSI) values of three fixed transmitter units are measured every 1.6 m in mesh format and analyzed by the classifiers, and robot position can be mapped in the indoor area. After navigation, the robot analyzes objects and detects and recognize human faces with the help of object recognition and facial recognition-based classification methods respectively. This robot detects the intruder with the current position in an indoor environment. Full article
(This article belongs to the Special Issue Cognitive Robotics)
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17 pages, 17926 KiB  
Article
Luenberger Position Observer Based on Deadbeat-Current Predictive Control for Sensorless PMSM
by Yuan Zhu, Ben Tao, Mingkang Xiao, Gang Yang, Xingfu Zhang and Ke Lu
Electronics 2020, 9(8), 1325; https://doi.org/10.3390/electronics9081325 - 16 Aug 2020
Cited by 22 | Viewed by 4896
Abstract
Two problems can cause control performance degradation on permanent magnet synchronous motor (PMSM) systems, namely, fluctuation of PMSM parameters and the time delay between current sampling and command value update. In order to reduce the influence of these problems, a new current-predictive control [...] Read more.
Two problems can cause control performance degradation on permanent magnet synchronous motor (PMSM) systems, namely, fluctuation of PMSM parameters and the time delay between current sampling and command value update. In order to reduce the influence of these problems, a new current-predictive control strategy is proposed in this article for medium- and high-speed PMSM. This strategy is based on the discrete mathematical model of PMSM. This new control strategy consists of two main steps: First, an integrator is applied to calculate current compensation value; second, the predictive current value is obtained through deadbeat-current predictive method. The stability of predictive control system is also proved in the article. With this deadbeat-current predictive control scheme, the real current can reach the desired value within one control-step. Based on this new current control method, Luenberger observer and phase-locked loop position tracker is applied in this article. Experimental results for 0.4 kW surface-mounted PMSM confirm the validity and excellent performance for parameters fluctuation of new current predictive control. Full article
(This article belongs to the Section Industrial Electronics)
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20 pages, 3306 KiB  
Article
A Review and Comparison of Solid, Multi-Strands and Litz Style PCB Winding
by Minh Huy Nguyen and Handy Fortin Blanchette
Electronics 2020, 9(8), 1324; https://doi.org/10.3390/electronics9081324 - 16 Aug 2020
Cited by 4 | Viewed by 5137
Abstract
At high frequency, AC resistance of a printed circuit board (PCB) winding becomes important and accounts for a large proportion of planar transformer losses. The winding is then influenced by both skin and proximity phenomenon, which makes the current distribution uneven resulting in [...] Read more.
At high frequency, AC resistance of a printed circuit board (PCB) winding becomes important and accounts for a large proportion of planar transformer losses. The winding is then influenced by both skin and proximity phenomenon, which makes the current distribution uneven resulting in an increased resistance. The study of improving AC resistance of a PCB winding has been tackled by many researchers. However, the lack of an overview and comparison among improvements has made it difficult to apply those methods to a specific winding. To overcome the above limitations, this paper investigates the pros and cons of three popular AC resistance optimizing methods: optimizing track width of a solid PCB winding, using multi-strands and using Litz style PCB winding. To verify the theoretical analysis, a total of 12 PCBs are simulated by finite element (FEM) and tested in the laboratory. Five criteria are analyzed, including skin resistance, proximity resistance, AC to DC ratio, total AC resistance and complexity are taken into consideration. The results of this study show that optimizing track width method has a significant improvement on AC resistance while the use of Litz PCB is effective for applications that need stable AC resistance in a wide frequency range. The use of parallel strands winding should be carefully considered as there is not significant benefit in both reducing the AC resistance and AC to DC ratio. Full article
(This article belongs to the Special Issue Design and Optimization of High-Frequency Power Converter)
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13 pages, 8720 KiB  
Article
Reconfigurable Hybrid Resonant Topology for Constant Current/Voltage Wireless Power Transfer of Electric Vehicles
by Sang-Hoon Hwang, Yafei Chen, Hailong Zhang, Kang-Yoon Lee and Dong-Hee Kim
Electronics 2020, 9(8), 1323; https://doi.org/10.3390/electronics9081323 - 16 Aug 2020
Cited by 12 | Viewed by 3344
Abstract
This paper proposes a reconfigurable hybrid topology (RHT) for the constant current (CC)/constant voltage (CV) charging of electric vehicles. The proposed system combines the series–series and the inductor and double capacitors-series topologies. Two AC switches (ACSs) are utilized to change the CC and [...] Read more.
This paper proposes a reconfigurable hybrid topology (RHT) for the constant current (CC)/constant voltage (CV) charging of electric vehicles. The proposed system combines the series–series and the inductor and double capacitors-series topologies. Two AC switches (ACSs) are utilized to change the CC and CV charging modes, without requiring an additional resonant network. A detailed analysis for designing the hybrid topology parameters is also presented; a three-kilowatt prototype was configured based on this analysis in order to validate the proposed system. The constructed prototype confirmed the stable mode changes, load fluctuations, CC/CV output characteristics and efficiency of the proposed system. The maximum efficiency of the proposed RHT was found to be 92.58%. Full article
(This article belongs to the Special Issue Emerging Technologies for Wireless Power Transfer in Transportation)
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22 pages, 5947 KiB  
Article
Predicting Car Availability in Free Floating Car Sharing Systems: Leveraging Machine Learning in Challenging Contexts
by Elena Daraio, Luca Cagliero, Silvia Chiusano, Paolo Garza and Danilo Giordano
Electronics 2020, 9(8), 1322; https://doi.org/10.3390/electronics9081322 - 16 Aug 2020
Cited by 9 | Viewed by 3106
Abstract
Free-Floating Car Sharing (FFCS) services are currently available in tens of cities and countries spread all over the worlds. Depending on citizens’ habits, service policies, and road conditions, car usage profiles are rather variable and often hardly predictable. Even within the same city, [...] Read more.
Free-Floating Car Sharing (FFCS) services are currently available in tens of cities and countries spread all over the worlds. Depending on citizens’ habits, service policies, and road conditions, car usage profiles are rather variable and often hardly predictable. Even within the same city, different usage trends emerge in different districts and in various time slots and weekdays. Therefore, modeling car availability in FFCS systems is particularly challenging. For these reasons, the research community has started to investigate the applicability of Machine Learning models to analyze FFCS usage data. This paper addresses the problem of predicting the short-term level of availability of the FFCS service in the short term. Specifically, it investigates the applicability of Machine Learning models to forecast the number of available car within a restricted urban area. It seeks the spatial and temporal contexts in which nonlinear ML models, trained on past usage data, are necessary to accurately predict car availability. Leveraging ML has shown to be particularly effective while considering highly dynamic urban contexts, where FFCS service usage is likely to suddenly and unexpectedly change. To tailor predictive models to the real FFCS data, we study also the influence of ML algorithm, prediction horizon, and characteristics of the neighborhood of the target area. The empirical outcomes allow us to provide system managers with practical guidelines to setup and tune ML models. Full article
(This article belongs to the Special Issue IoT Technologies for Smart Cities)
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13 pages, 3012 KiB  
Article
Modified U-Shaped Resonator as Decoupling Structure in MIMO Antenna
by Amjad Iqbal, Ahsan Altaf, Mujeeb Abdullah, Mohammad Alibakhshikenari, Ernesto Limiti and Sunghwan Kim
Electronics 2020, 9(8), 1321; https://doi.org/10.3390/electronics9081321 - 16 Aug 2020
Cited by 41 | Viewed by 4332
Abstract
This paper presents an isolation enhancement of two closely packed multiple-input multiple-output (MIMO) antenna system using a modified U-shaped resonator. The modified U-shaped resonator is placed between two closely packed radiating elements resonating at 5.4 GHz with an edge to edge separation distance [...] Read more.
This paper presents an isolation enhancement of two closely packed multiple-input multiple-output (MIMO) antenna system using a modified U-shaped resonator. The modified U-shaped resonator is placed between two closely packed radiating elements resonating at 5.4 GHz with an edge to edge separation distance of 5.82 mm (λ/10). Through careful adjustment of parametric modelling, the isolation level of −23 dB among the densely packed elements is achieved. The coupling behaviour of the MIMO elements is analysed by accurately designing the equivalent circuit model in each step. The antenna performance is realized in the presence and absence of decoupling structure, and the results shows negligible effects on the antenna performance apart from mutual coupling. The simple assembly of the proposed modified U-shaped isolating structure makes it useful for several linked applications. The proposed decoupling structure is compact in nature, suppress the undesirable coupling generated by surface wave and nearby fields, and is easy to fabricate. Full article
(This article belongs to the Special Issue Recent Advances in Antenna Design for 5G Heterogeneous Networks)
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19 pages, 13644 KiB  
Article
CoAP-Based Streaming Control for IoT Applications
by Joong-Hwa Jung, Moneeb Gohar and Seok-Joo Koh
Electronics 2020, 9(8), 1320; https://doi.org/10.3390/electronics9081320 - 16 Aug 2020
Cited by 7 | Viewed by 3605
Abstract
The Constrained Application Protocol (CoAP) is a representative messaging protocol for Internet of Things (IoT) applications. It is noted that a lot of IoT-based streaming applications have been recently deployed. Typically, CoAP uses User Datagram Protocol (UDP) as its underlying protocol for lightweight [...] Read more.
The Constrained Application Protocol (CoAP) is a representative messaging protocol for Internet of Things (IoT) applications. It is noted that a lot of IoT-based streaming applications have been recently deployed. Typically, CoAP uses User Datagram Protocol (UDP) as its underlying protocol for lightweight messaging. However, it cannot provide reliability, since it is based on UDP. Thus, the CoAP over Transmission Control Protocol (TCP) was recently proposed so as to provide reliability. However, the existing schemes do not provide the error handling and flow controls suitably for IoT-based streaming applications. This tends to induce throughput degradation in wireless lossy networks. In this paper, we propose a CoAP-based streaming control (CoAP-SC) scheme, which is an extension of CoAP over UDP with error handling and flow control for throughput enhancement. The proposed CoAP-SC scheme is designed by considering the sequence number of data message, the use of ACK messages, and the buffer size of sending buffer. To do this, a new CoAP option is defined. For performance analysis, the proposed scheme is implemented and compared with the existing schemes. From the testbed experimentations in various network environments, we see that the proposed CoAP-SC scheme can provide better throughput than the existing CoAP-based schemes by performing the error handling and flow control operations effectively. Full article
(This article belongs to the Special Issue IoT Services, Applications, Platform, and Protocols)
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12 pages, 5817 KiB  
Article
An Energy-Efficient Integration of a Digital Modulator and a Class-D Amplifier
by Muhammad Yousuf Irfan Zia, Raúl Tierno, Miguel-Ángel Luque-Nieto and Pablo Otero
Electronics 2020, 9(8), 1319; https://doi.org/10.3390/electronics9081319 - 16 Aug 2020
Cited by 1 | Viewed by 3194
Abstract
Energy consumption is always a key feature in devices powered by electric accumulators. The power amplifier is the most energy-demanding module in mobile devices, portable appliances, static transceivers, and even nodes used in underwater acoustic networks. These devices incorporate a modulator, typically a [...] Read more.
Energy consumption is always a key feature in devices powered by electric accumulators. The power amplifier is the most energy-demanding module in mobile devices, portable appliances, static transceivers, and even nodes used in underwater acoustic networks. These devices incorporate a modulator, typically a pulse-width modulation (PWM) and a class-D power amplifier, for higher efficiency. We propose a technique to integrate the modulator of a transmitter and PW-modulator of a class-D amplifier to improve the overall efficiency of the system. This integrated set operates as an up-converter, phase modulator (PM), and binary phase-shift keying (BPSK) modulator under certain conditions. The theoretical concept is verified using Matlab and a model is designed and simulated in Simulink. For validation purposes, an electronic circuit is built and tested using Multisim. The results obtained by simulations and circuit implementation show that the proposed integrated system is an energy-efficient and cost-effective solution compared to conventional techniques. Full article
(This article belongs to the Special Issue Underwater Communication and Networking Systems)
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15 pages, 3600 KiB  
Article
One-Dimensional Convolutional Neural Networks with Feature Selection for Highly Concise Rule Extraction from Credit Scoring Datasets with Heterogeneous Attributes
by Yoichi Hayashi and Naoki Takano
Electronics 2020, 9(8), 1318; https://doi.org/10.3390/electronics9081318 - 16 Aug 2020
Cited by 11 | Viewed by 4304
Abstract
Convolution neural networks (CNNs) have proven effectiveness, but they are not applicable to all datasets, such as those with heterogeneous attributes, which are often used in the finance and banking industries. Such datasets are difficult to classify, and to date, existing high-accuracy classifiers [...] Read more.
Convolution neural networks (CNNs) have proven effectiveness, but they are not applicable to all datasets, such as those with heterogeneous attributes, which are often used in the finance and banking industries. Such datasets are difficult to classify, and to date, existing high-accuracy classifiers and rule-extraction methods have not been able to achieve sufficiently high classification accuracies or concise classification rules. This study aims to provide a new approach for achieving transparency and conciseness in credit scoring datasets with heterogeneous attributes by using a one-dimensional (1D) fully-connected layer first CNN combined with the Recursive-Rule Extraction (Re-RX) algorithm with a J48graft decision tree (hereafter 1D FCLF-CNN). Based on a comparison between the proposed 1D FCLF-CNN and existing rule extraction methods, our architecture enabled the extraction of the most concise rules (6.2) and achieved the best accuracy (73.10%), i.e., the highest interpretability–priority rule extraction. These results suggest that the 1D FCLF-CNN with Re-RX with J48graft is very effective for extracting highly concise rules for heterogeneous credit scoring datasets. Although it does not completely overcome the accuracy–interpretability dilemma for deep learning, it does appear to resolve this issue for credit scoring datasets with heterogeneous attributes, and thus, could lead to a new era in the financial industry. Full article
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22 pages, 1820 KiB  
Article
Lexicon-based Sentiment Analysis Using the Particle Swarm Optimization
by Kristína Machová, Martin Mikula, Xiaoying Gao and Marian Mach
Electronics 2020, 9(8), 1317; https://doi.org/10.3390/electronics9081317 - 15 Aug 2020
Cited by 26 | Viewed by 4037
Abstract
This work belongs to the field of sentiment analysis; in particular, to opinion and emotion classification using a lexicon-based approach. It solves several problems related to increasing the effectiveness of opinion classification. The first problem is related to lexicon labelling. Human labelling in [...] Read more.
This work belongs to the field of sentiment analysis; in particular, to opinion and emotion classification using a lexicon-based approach. It solves several problems related to increasing the effectiveness of opinion classification. The first problem is related to lexicon labelling. Human labelling in the field of emotions is often too subjective and ambiguous, and so the possibility of replacement by automatic labelling is examined. This paper offers experimental results using a nature-inspired algorithm—particle swarm optimization—for labelling. This optimization method repeatedly labels all words in a lexicon and evaluates the effectiveness of opinion classification using the lexicon until the optimal labels for words in the lexicon are found. The second problem is that the opinion classification of texts which do not contain words from the lexicon cannot be successfully done using the lexicon-based approach. Therefore, an auxiliary approach, based on a machine learning method, is integrated into the method. This hybrid approach is able to classify more than 99% of texts and achieves better results than the original lexicon-based approach. The final hybrid model can be used for emotion analysis in human–robot interactions. Full article
(This article belongs to the Special Issue Human Computer Interaction for Intelligent Systems)
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15 pages, 3618 KiB  
Article
Unified System Network Architecture: Flexible and Area-Efficient NoC Architecture with Multiple Ports and Cores
by Phan-Duy Bui and Chanho Lee
Electronics 2020, 9(8), 1316; https://doi.org/10.3390/electronics9081316 - 15 Aug 2020
Cited by 6 | Viewed by 2970
Abstract
In recent years, as semiconductor manufacturing processes have been steadily scaled down, the transistor count fabricated on a single silicon die can reach up to a billion units. Therefore, current multiprocessor system-on-chips (MPSoCs) can include up to hundreds or even thousands of cores [...] Read more.
In recent years, as semiconductor manufacturing processes have been steadily scaled down, the transistor count fabricated on a single silicon die can reach up to a billion units. Therefore, current multiprocessor system-on-chips (MPSoCs) can include up to hundreds or even thousands of cores and additional accelerators for high-performance systems. Network-on-chips (NoCs) have become an attractive solution for interconnects, which are critical components of MPSoCs in terms of system performance. In this study, a highly flexible and area-efficient NoC architecture, namely the unified system network architecture (USNA), which can be tailored for various topologies, is proposed. The USNA provides high flexibility in port placements with varying numbers of local cores and router linkers. It also supports quality of service operations for both the router and linker. The network performance (e.g., average latency and saturated throughput) and implementation cost of the USNA, using various network configurations for the same number of local cores under uniform random traffic conditions, were investigated in this study. According to the simulation results, the performance of the USNA is better or similar to other NoCs, with a significantly smaller area and lower power consumption. Full article
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21 pages, 3084 KiB  
Review
Supply-Scalable High-Speed I/O Interfaces
by Woorham Bae
Electronics 2020, 9(8), 1315; https://doi.org/10.3390/electronics9081315 - 15 Aug 2020
Cited by 7 | Viewed by 5970
Abstract
Improving the energy efficiency of computer communication is becoming more and more important as the world is creating a massive amount of data, while the interface has been a bottleneck due to the finite bandwidth of electrical wires. Introducing supply voltage scalability is [...] Read more.
Improving the energy efficiency of computer communication is becoming more and more important as the world is creating a massive amount of data, while the interface has been a bottleneck due to the finite bandwidth of electrical wires. Introducing supply voltage scalability is expected to significantly improve the energy efficiency of communication input/output (I/O) interfaces as well as make the I/Os efficiently adapt to actual utilization. However, there are many challenges to be addressed to facilitate the realization of a true sense of supply-scalable I/O. This paper reviews the motivations, background theories, design considerations, and challenges of scalable I/Os from the viewpoint of computer architecture down to the transistor level. Thereafter, a survey of the state-of-the-arts fabricated designs is discussed. Full article
(This article belongs to the Special Issue Low-Voltage Integrated Circuits Design and Application)
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20 pages, 7016 KiB  
Article
Efficiency of Cascaded Neural Networks in Detecting Initial Damage to Induction Motor Electric Windings
by Maciej Skowron and Teresa Orłowska-Kowalska
Electronics 2020, 9(8), 1314; https://doi.org/10.3390/electronics9081314 - 15 Aug 2020
Cited by 9 | Viewed by 2445
Abstract
This article presents the efficiency of using cascaded neural structures in the process of detecting damage to electrical circuits in a squirrel cage induction motor (IM) supplied from a frequency converter. The authors present the idea of a sequential connection of classic neural [...] Read more.
This article presents the efficiency of using cascaded neural structures in the process of detecting damage to electrical circuits in a squirrel cage induction motor (IM) supplied from a frequency converter. The authors present the idea of a sequential connection of classic neural structures to increase the efficiency of damage classification and detection presented by individual neural structures, especially in the initial phase of single or multiple electrical failures. The easily measurable axial flux signal is used as a source of diagnostic information. The developed cascaded neural networks are implemented in the measurement and diagnostic software made in the LabVIEW environment. The results of the experimental research on a 1.5 kW IM supplied by an industrial frequency converter confirm the high efficiency of the use of the developed cascaded neural structures in the detection of incipient stator and rotor winding faults, namely inter-turn stator winding short circuits and broken rotor bars, as well as mixed failures in the entire range of changes of the load torque and supply voltage frequency. Full article
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13 pages, 1226 KiB  
Article
PESL: System-Level Estimation of Power-Management Effect on Dynamic Energy Consumption
by Jaroslav Erdelyi, Dominik Macko and Katarina Jelemenska
Electronics 2020, 9(8), 1313; https://doi.org/10.3390/electronics9081313 - 15 Aug 2020
Cited by 3 | Viewed by 2765
Abstract
Power estimation is one of the key aspects that can help designers create digital circuits more effectively. If a designer is able to estimate circuit parameters during the early stages of development, correct decisions can be made that can significantly shorten the design [...] Read more.
Power estimation is one of the key aspects that can help designers create digital circuits more effectively. If a designer is able to estimate circuit parameters during the early stages of development, correct decisions can be made that can significantly shorten the design time. The early design stages are represented by modeling at the system level of abstraction. However, existing system-level power/energy estimation methods are either too complicated, or they do not consider power management when estimating power consumption, meaning they are inaccurate. Therefore, in this paper we propose a method for a more accurate system-level estimation of the dynamic energy consumption by considering the impact of power management. The SystemC description of a power-managed system and the simulation results (in the form of the value change dump (VCD)) are inputs to the estimation method. The proposed method is based on an activity profile using the modified Hamming distance computation. The method is especially useful for the exploration of alternative power-management strategies, and it helps the designer to select the most efficient strategy. Full article
(This article belongs to the Special Issue Low-Voltage Integrated Circuits Design and Application)
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20 pages, 3335 KiB  
Article
Upsampling Real-Time, Low-Resolution CCTV Videos Using Generative Adversarial Networks
by Debapriya Hazra and Yung-Cheol Byun
Electronics 2020, 9(8), 1312; https://doi.org/10.3390/electronics9081312 - 14 Aug 2020
Cited by 5 | Viewed by 4252
Abstract
Video super-resolution has become an emerging topic in the field of machine learning. The generative adversarial network is a framework that is widely used to develop solutions for low-resolution videos. Video surveillance using closed-circuit television (CCTV) is significant in every field, all over [...] Read more.
Video super-resolution has become an emerging topic in the field of machine learning. The generative adversarial network is a framework that is widely used to develop solutions for low-resolution videos. Video surveillance using closed-circuit television (CCTV) is significant in every field, all over the world. A common problem with CCTV videos is sudden video loss or poor quality. In this paper, we propose a generative adversarial network that implements spatio-temporal generators and discriminators to enhance real-time low-resolution CCTV videos to high-resolution. The proposed model considers both foreground and background motion of a CCTV video and effectively models the spatial and temporal consistency from low-resolution video frames to generate high-resolution videos. Quantitative and qualitative experiments on benchmark datasets, including Kinetics-700, UCF101, HMDB51 and IITH_Helmet2, showed that our model outperforms the existing GAN models for video super-resolution. Full article
(This article belongs to the Special Issue Intelligent Closed-Circuit Television and Applications)
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11 pages, 2151 KiB  
Article
Pixel-Based Approach for Generating Original and Imitating Evolutionary Art
by Yuchen Wang and Rong Xie
Electronics 2020, 9(8), 1311; https://doi.org/10.3390/electronics9081311 - 14 Aug 2020
Viewed by 2528
Abstract
We proposed a pixel-based evolution method to automatically generate evolutionary art. Our method can generate diverse artworks, including original artworks and imitating artworks, with different artistic styles and high visual complexity. The generation process is fully automated. In order to adapt to the [...] Read more.
We proposed a pixel-based evolution method to automatically generate evolutionary art. Our method can generate diverse artworks, including original artworks and imitating artworks, with different artistic styles and high visual complexity. The generation process is fully automated. In order to adapt to the pixel-based method, a von Neumann neighbor topology-modified particle swarm optimization (PSO) is employed to the proposed method. The fitness functions of PSO are well prepared. Firstly, we come up with a set of aesthetic fitness functions. Next, the imitating fitness function is designed. Finally, the aesthetic fitness functions and the imitating fitness function are weighted into one single object function, which is used in the modified PSO. Both the original outputs and imitating outputs are shown. A questionnaire is designed to investigate the subjective aesthetic feeling of proposed evolutionary art, and the statistics are shown. Full article
(This article belongs to the Special Issue Evolutionary Machine Learning for Nature-Inspired Problem Solving)
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18 pages, 4001 KiB  
Article
Analysis of Challenges Due to Changes in Net Load Curve in South Korea by Integrating DERs
by Chi-Yeon Kim, Chae-Rin Kim, Dong-Keun Kim and Soo-Hwan Cho
Electronics 2020, 9(8), 1310; https://doi.org/10.3390/electronics9081310 - 14 Aug 2020
Cited by 1 | Viewed by 2822
Abstract
The development of Distributed Energy Resources (DERs) is essential in accordance with the mandatory greenhouse gas (GHG) emission reduction policies, resulting in many DERs being integrated into the power system. Currently, South Korea is also focusing on increasing the penetration of renewable energy [...] Read more.
The development of Distributed Energy Resources (DERs) is essential in accordance with the mandatory greenhouse gas (GHG) emission reduction policies, resulting in many DERs being integrated into the power system. Currently, South Korea is also focusing on increasing the penetration of renewable energy sources (RES) and EV by 2030 to reduce GHGs. However, indiscriminate DER development can give a negative impact on the operation of existing power systems. The existing power system operation is optimized for the hourly net load pattern, but the integration of DERs changes it. In addition, since ToU (Time-of-Use) tariff and Demand Response (DR) programs are very sensitive to changes in the net load curve, it is essential to predict the hourly net load pattern accurately for the modification of pricing and demand response programs in the future. However, a long-term demand forecast in South Korea provides only the total amount of annual load (TWh) and the expected peak load level (GW) in summer and winter seasons until 2030. In this study, we use the annual photovoltaic (PV) installed capacity, PV generation, and the number of EV based on the target values for 2030 in South Korea to predict the change in hourly net load curve by year and season. In addition, to predict the EV charging load curve based on Monte Carlo simulation, the EV users’ charging method, charging start time, and State-of-Charge (SoC) were considered. Finally, we analyze the change in hourly net load curve due to the integration of PV and EV to determine the amplification of the duck curve and peak load time by year and season, and present the risks caused by indiscriminate DERs development. Full article
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13 pages, 2906 KiB  
Article
Semantic Segmentation of Conjunctiva Region for Non-Invasive Anemia Detection Applications
by Sivachandar Kasiviswanathan, Thulasi Bai Vijayan, Lorenzo Simone and Giovanni Dimauro
Electronics 2020, 9(8), 1309; https://doi.org/10.3390/electronics9081309 - 14 Aug 2020
Cited by 26 | Viewed by 5047
Abstract
Technology is changing the future of healthcare, technology-supported non-invasive medical procedures are more preferable in the medical diagnosis. Anemia is one of the widespread diseases affecting the wellbeing of individuals around the world especially childbearing age women and children and addressing this issue [...] Read more.
Technology is changing the future of healthcare, technology-supported non-invasive medical procedures are more preferable in the medical diagnosis. Anemia is one of the widespread diseases affecting the wellbeing of individuals around the world especially childbearing age women and children and addressing this issue with the advanced technology will reduce the prevalence in large numbers. The objective of this work is to perform segmentation of the conjunctiva region for non-invasive anemia detection applications using deep learning. The proposed U-Net Based Conjunctiva Segmentation Model (UNBCSM) uses fine-tuned U-Net architecture for effective semantic segmentation of conjunctiva from the digital eye images captured by consumer-grade cameras in an uncontrolled environment. The ground truth for this supervised learning was given as Pascal masks obtained by manual selection of conjunctiva pixels. Image augmentation and pre-processing was performed to increase the data size and the performance of the model. UNBCSM showed good segmentation results and exhibited a comparable value of Intersection over Union (IoU) score between the ground truth and the segmented mask of 96% and 85.7% for training and validation, respectively. Full article
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18 pages, 2602 KiB  
Article
A Novel Data-Driven Specific Emitter Identification Feature Based on Machine Cognition
by Mingzhe Zhu, Zhenpeng Feng and Xianda Zhou
Electronics 2020, 9(8), 1308; https://doi.org/10.3390/electronics9081308 - 14 Aug 2020
Cited by 18 | Viewed by 2610
Abstract
Machine learning becomes increasingly promising in specific emitter identification (SEI), particularly in feature extraction and target recognition. Traditional features, such as radio frequency (RF), pulse amplitude (PA), power spectral density (PSD), and etc., usually show limited recognition effects when only a slight difference [...] Read more.
Machine learning becomes increasingly promising in specific emitter identification (SEI), particularly in feature extraction and target recognition. Traditional features, such as radio frequency (RF), pulse amplitude (PA), power spectral density (PSD), and etc., usually show limited recognition effects when only a slight difference exists in radar signals. Numerous two-dimensional features on transform domain, like various time-frequency representation and ambiguity function are used to augment information abundance, whereas the unacceptable computational burden usually emerges. To solve this problem, some artfully handcrafted features in transformed domain are proposed, like representative slice of ambiguity function (AF-RS) and compressed sensing mask (CS-MASK), to extract representative information that contributes to machine recognition task. However, most handcrafted features only utilizing neural network as a classifier, few of them focus on mining deep informative features from the perspective of machine cognition. Such feature extraction that is based on human cognition instead of machine cognition may probably miss some seemingly nominal texture information which actually contributes greatly to recognition, or collect too much redundant information. In this paper, a novel data-driven feature extraction is proposed based on machine cognition (MC-Feature) resort to saliency detection. Saliency detection exhibits positive contributions and suppresses irrelevant contributions in a transform domain with the help of a saliency map calculated from the accumulated gradients of each neuron to input data. Finally, positive and irrelevant contributions in the saliency map are merged into a new feature. Numerous experimental results demonstrate that the MC-feature can greatly strengthen the slight intra-class difference in SEI and provides a possibility of interpretation of CNN. Full article
(This article belongs to the Special Issue Theory and Applications in Digital Signal Processing)
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18 pages, 5988 KiB  
Article
Compact Wideband MIMO Diversity Antenna for Mobile Applications Using Multi-Layered Structure
by Omer Arabi, Chan Hwang See, Atta Ullah, Nazar Ali, Bo Liu, Raed Abd-Alhameed, Neil J. McEwan and Peter S. Excell
Electronics 2020, 9(8), 1307; https://doi.org/10.3390/electronics9081307 - 14 Aug 2020
Cited by 10 | Viewed by 4485
Abstract
A closely packed wideband multiple-input multiple-output (MIMO)/diversity antenna (of two ports) with a small size of less than 18.5 mm by 18.5 mm is proposed for mobile communication applications. The antenna can be orthogonally configured for corner installation or by placing it on [...] Read more.
A closely packed wideband multiple-input multiple-output (MIMO)/diversity antenna (of two ports) with a small size of less than 18.5 mm by 18.5 mm is proposed for mobile communication applications. The antenna can be orthogonally configured for corner installation or by placing it on a back-to-back structure for compact modules. To enhance the isolation and widen the bandwidth, the antenna is structured with multiple layers having differing dielectric constants. The feeding through a via significantly reduces the ground waves. A multi-fidelity surrogate model-assisted design exploration method is employed to obtain the optimized antenna geometric parameters efficiently. The antenna design was investigated using electromagnetic simulation and a physical realization of the optimal design was then created and subjected to a range of tests. The specific parameters investigated included reflection coefficients, mutual coupling between the input ports, radiation patterns, efficiency and parameters specific to MIMO behavior: envelope correlation coefficient and pattern diversity multiplexing coefficient. It was found that the antenna has an impedance bandwidth of approximately 4 GHz, mutual coupling between input ports of better than −18 dB and an envelope correlation coefficient of less than 0.002 across the operating band. This makes it a good candidate design for many mobile MIMO applications. Full article
(This article belongs to the Special Issue Design and Theoretical Study of New Antennas)
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35 pages, 2942 KiB  
Review
Enabling Emergent Configurations in the Industrial Internet of Things for Oil and Gas Explorations: A Survey
by Owoicho E. Ijiga, Reza Malekian and Uche A. K. Chude-Okonkwo
Electronics 2020, 9(8), 1306; https://doi.org/10.3390/electronics9081306 - 14 Aug 2020
Cited by 8 | Viewed by 4079
Abstract
Several heterogeneous, intelligent, and distributed devices can be connected to interact with one another over the Internet in what is termed internet of things (IoT). Also, the concept of IoT can be exploited in the industrial environment for enhancing the production of goods [...] Read more.
Several heterogeneous, intelligent, and distributed devices can be connected to interact with one another over the Internet in what is termed internet of things (IoT). Also, the concept of IoT can be exploited in the industrial environment for enhancing the production of goods and services and for mitigating the risk of disaster occurrences. This application of IoT for enhancing industrial production is known as industrial IoT (IIoT). Emergent configuration (EC) is a technology that can be adopted to enhance the operation and collaboration of IoT connected devices in order to improve the efficiency of the connected IoT systems for maximum user satisfaction. To meet user goals, the connected devices are required to cooperate with one another in an adaptive, interoperable, and homogeneous manner. In this paper, a survey of the concept of IoT is presented in addition to a review of IIoT systems. The application of ubiquitous computing-aided software define networking (SDN)-based EC architecture is propounded for enhancing the throughput of oil and gas production in the maritime ecosystems by managing the exploration process especially in emergency situations that involve anthropogenic oil and gas spillages. Full article
(This article belongs to the Special Issue Internet of Things for Industrial Applications)
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14 pages, 4201 KiB  
Article
Characterization of Self-Heating Process in GaN-Based HEMTs
by Daniel Gryglewski, Wojciech Wojtasiak, Eliana Kamińska and Anna Piotrowska
Electronics 2020, 9(8), 1305; https://doi.org/10.3390/electronics9081305 - 13 Aug 2020
Cited by 17 | Viewed by 4301
Abstract
Thermal characterization of modern microwave power transistors such as high electron-mobility transistors based on gallium nitride (GaN-based HEMTs) is a critical challenge for the development of high-performance new generation wireless communication systems (LTE-A, 5G) and advanced radars (active electronically scanned array (AESA)). This [...] Read more.
Thermal characterization of modern microwave power transistors such as high electron-mobility transistors based on gallium nitride (GaN-based HEMTs) is a critical challenge for the development of high-performance new generation wireless communication systems (LTE-A, 5G) and advanced radars (active electronically scanned array (AESA)). This is especially true for systems operating with variable-envelope signals where accurate determination of self-heating effects resulting from strong- and fast-changing power dissipated inside transistor is crucial. In this work, we have developed an advanced measurement system based on DeltaVGS method with implemented software enabling accurate determination of device channel temperature and thermal resistance. The methodology accounts for MIL-STD-750-3 standard but takes into account appropriate specific bias and timing conditions. Three types of GaN-based HEMTs were taken into consideration, namely commercially available GaN-on-SiC (CGH27015F and TGF2023-2-01) and GaN-on-Si (NPT2022) devices, as well as model GaN-on-GaN HEMT (T8). Their characteristics of thermal impedance, thermal time constants and thermal equivalent circuits were presented. Knowledge of thermal equivalent circuits and electro–thermal models can lead to improved design of GaN HEMT high-power amplifiers with account of instantaneous temperature variations for systems using variable-envelope signals. It can also expand their range of application. Full article
(This article belongs to the Special Issue Micro- and Nanotechnology of Wide Bandgap Semiconductors)
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27 pages, 747 KiB  
Article
NVM-Shelf: Secure Hybrid Encryption with Less Flip for Non-Volatile Memory
by Thomas Haywood Dadzie, Jiwon Lee, Jihye Kim and Hyunok Oh
Electronics 2020, 9(8), 1304; https://doi.org/10.3390/electronics9081304 - 13 Aug 2020
Viewed by 2503
Abstract
The Non-Volatile Memory (NVM), such as PRAM or STT-MRAM, is often adopted as the main memory in portable embedded systems. The non-volatility triggers a security issue against physical attacks, which is a vulnerability caused by memory extraction and snapshots. However, simply encrypting the [...] Read more.
The Non-Volatile Memory (NVM), such as PRAM or STT-MRAM, is often adopted as the main memory in portable embedded systems. The non-volatility triggers a security issue against physical attacks, which is a vulnerability caused by memory extraction and snapshots. However, simply encrypting the NVM degrades the performance of the memory (high energy consumption, short lifetime), since typical encryption causes an avalanche effect while most NVMs suffer from the memory-write operation. In this paper, we propose NVM-shelf: Secure Hybrid Encryption with Less Flip (shelf) for Non-Volatile Memory (NVM), which is hybrid encryption to reduce the flip penalty. The main idea is that a stream cipher, such as block cipher CTR mode, is flip-tolerant when the keystream is reused. By modifying the CTR mode in AES block cipher, we let the keystream updated in a short period and reuse the keystream to achieve flip reduction while maintaining security against physical attacks. Since the CTR mode requires additional storage for the nonce, we classify write-intensive cache blocks and apply our CTR mode to the write-intensive blocks and apply the ECB mode for the rest of the blocks. To extend the cache-based NVM-shelf implementation toward SPM-based systems, we also propose an efficient compiler for SA-SPM: Security-Aware Scratch Pad Memory, which ensures the security of main memories in SPM-based embedded systems. Our compiler is the first approach to support full encryption of memory regions (i.e., stack, heap, code, and static variables) in an SPM-based system. By integrating the NVM-shelf framework to the SA-SPM compiler, we obtain the NVM-shelf implementation for both cache-based and SPM-based systems. The cache-based experiment shows that the NVM-shelf achieves encryption flip penalty less than 3%, and the SPM-based experiment shows that the NVM-shelf reduces the flip penalty by 31.8% compared to the whole encryption. Full article
(This article belongs to the Special Issue Embedded IoT: System Design and Applications)
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18 pages, 14164 KiB  
Article
Frequency-Tracking Algorithm Based on SOGI-FLL for Wireless Power Transfer System to Operate ZPA Region
by Do-Hyun Kim, Min-Soo Kim and Hee-Je Kim
Electronics 2020, 9(8), 1303; https://doi.org/10.3390/electronics9081303 - 13 Aug 2020
Cited by 6 | Viewed by 2607
Abstract
The wireless power transfer (WPT) system has attracted attention for energy transmission without physical contact. However, a WPT system has low coupling condition because of a big air gap between transmitter and receiver coils. The low coupling condition has a high leakage inductance. [...] Read more.
The wireless power transfer (WPT) system has attracted attention for energy transmission without physical contact. However, a WPT system has low coupling condition because of a big air gap between transmitter and receiver coils. The low coupling condition has a high leakage inductance. To overcome this problem, we design a proposed system for WPT using series-series (S-S) topology of one resonant circuit. To obtain the higher efficiency power conversion of the WPT system, it has to operate the resonant frequency in the zero phase angle (ZPA) point even under mutual coefficient and load variation. Therefore, we propose the resonant frequency tracking algorithm to operate ZPA point based on the second order generalized integrator-frequency locked loop (SOGI-FLL) method. This proposed frequency-tracking algorithm can estimate ZPA point by changing switching frequency. We can reduce the switching loss with this proposed algorithm and improve the low conversion efficiency of the WPT system. The performance of the proposed frequency-tracking algorithm is automatically verified through various coupling coefficients and the load variation. Full article
(This article belongs to the Section Computer Science & Engineering)
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