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Electronics, Volume 8, Issue 1 (January 2019)

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Cover Story (view full-size image) Current trends in cyber–physical system design include devices with robotic hands capable of [...] Read more.
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Open AccessArticle
A 10 kW ZVS Integrated Boost Dual Three-Phase Bridge DC–DC Resonant Converter for a Linear Generator-Based Wave-Energy System: Design and Simulation
Electronics 2019, 8(1), 115; https://doi.org/10.3390/electronics8010115
Received: 14 January 2019 / Accepted: 16 January 2019 / Published: 21 January 2019
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Abstract
The design and performance analysis of a 10 kW three-phase DC–DC LCL-type resonant converter having a built-in boost function were carried out. This high-power converter is proposed for its application in grid-interfacing a linear generator (LG)-based wave-energy system. Fixed-frequency control is used, and [...] Read more.
The design and performance analysis of a 10 kW three-phase DC–DC LCL-type resonant converter having a built-in boost function were carried out. This high-power converter is proposed for its application in grid-interfacing a linear generator (LG)-based wave-energy system. Fixed-frequency control is used, and the converter was designed to operate with a lagging power factor. It is shown that all switches turn on with zero-voltage switching (ZVS) for wide input voltage and load variations. This results in reduced switching losses and stresses, which is very important in large-power applications. The performance of the converter was studied through PSIM simulation software. Theoretical and simulation results are presented for comparison. Power-loss break-down analysis of the designed converter was carried out and the summary of results is presented. Full article
(This article belongs to the Special Issue Advanced Power Conversion Technologies)
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Open AccessFeature PaperReview
Recent Progress in the Design of 4G/5G Reconfigurable Filters
Electronics 2019, 8(1), 114; https://doi.org/10.3390/electronics8010114
Received: 22 December 2018 / Revised: 9 January 2019 / Accepted: 16 January 2019 / Published: 20 January 2019
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Abstract
Currently, several microwave filter designs contend for use in wireless communications. Among various microstrip filter designs, the reconfigurable planar filter presents more advantages and better prospects for communication applications, being compact in size, light-weight and cost-effective. Tuneable microwave filters can reduce the number [...] Read more.
Currently, several microwave filter designs contend for use in wireless communications. Among various microstrip filter designs, the reconfigurable planar filter presents more advantages and better prospects for communication applications, being compact in size, light-weight and cost-effective. Tuneable microwave filters can reduce the number of switches between electronic components. This paper presents a review of recent reconfigurable microwave filter designs, specifically on current advances in tuneable filters that involve high-quality factor resonator filters to control frequency, bandwidth and selectivity. The most important materials required for this field are also highlighted and surveyed. In addition, the main references for several types of tuneable microstrip filters are reported, especially related to new design technologies. Topics surveyed include microwave and millimetre wave designs for 4G and 5G applications, which use varactors and MEMSs technologies. Full article
(This article belongs to the Special Issue Recent Technical Developments in Energy-Efficient 5G Mobile Cells)
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Open AccessArticle
The Role of Diversity on Linear Scattering Operator: The Case of Strip Scatterers Observed under the Fresnel Approximation
Electronics 2019, 8(1), 113; https://doi.org/10.3390/electronics8010113
Received: 11 December 2018 / Revised: 14 January 2019 / Accepted: 18 January 2019 / Published: 20 January 2019
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Abstract
The aim of this paper is to investigate the role of multiple views and multiple frequencies in linear inverse scattering problems. The study was performed assuming the Fresnel-zone approximation on the scattering operator. Due to the crucial role played by singular values into [...] Read more.
The aim of this paper is to investigate the role of multiple views and multiple frequencies in linear inverse scattering problems. The study was performed assuming the Fresnel-zone approximation on the scattering operator. Due to the crucial role played by singular values into analysing the linear inverse scattering problems, the impact of view and frequency diversities on singular values behaviour was established. In fact, the singular values were related to the most common metrics used to quantify the achievable performances in inverse scattering problems, such as the number of degrees of freedom (NDF), the information content and the resolution. Full article
(This article belongs to the Special Issue Microwave Imaging and Its Application)
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Open AccessArticle
A Hybrid Current Mode Controller with Fast Response Characteristics for Super Capacitor Applications
Electronics 2019, 8(1), 112; https://doi.org/10.3390/electronics8010112
Received: 18 December 2018 / Revised: 13 January 2019 / Accepted: 15 January 2019 / Published: 19 January 2019
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Abstract
A wide-bandwidth current-controller is required for the fast charging and discharging of applications containing super capacitors. To accomplish this, peak current mode is generally used due to the speed of its response characteristics. On the other hand, peak current mode control must be [...] Read more.
A wide-bandwidth current-controller is required for the fast charging and discharging of applications containing super capacitors. To accomplish this, peak current mode is generally used due to the speed of its response characteristics. On the other hand, peak current mode control must be provided with a slope compensation function to restrain sub-harmonic oscillations. However, if the controlled output voltage is varied, the slope must be changed accordingly. Nonetheless, it is not easy to change the slope for every change in output voltage. Another solution involves the slope being set at the maximum value, which results in a slow response. Therefore, in this paper, a hybrid mode controller was proposed that uses a peak current and a newly-specified valley current. Using the proposed hybrid mode control, sub-harmonic oscillation did not occur for duty cycles larger than 0.5 and response times were fast. Full article
(This article belongs to the Special Issue Advanced Power Conversion Technologies)
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Open AccessArticle
Optimal Power Flow Controller for Grid-Connected Microgrids using Grasshopper Optimization Algorithm
Electronics 2019, 8(1), 111; https://doi.org/10.3390/electronics8010111
Received: 27 December 2018 / Revised: 12 January 2019 / Accepted: 15 January 2019 / Published: 19 January 2019
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Abstract
Despite the vast benefits of integrating renewable energy sources (RES) with the utility grid, they pose stability and power quality problems when interconnected with the existing power system. This is due to the production of high voltages and current overshoots/undershoots during their injection [...] Read more.
Despite the vast benefits of integrating renewable energy sources (RES) with the utility grid, they pose stability and power quality problems when interconnected with the existing power system. This is due to the production of high voltages and current overshoots/undershoots during their injection or disconnection into/from the power system. In addition, the high harmonic distortion in the output voltage and current waveforms may also be observed due to the excessive inverter switching frequencies used for controlling distributed generator’s (DG) power output. Hence, the development of a robust and intelligent controller for the grid-connected microgrid (MG) is the need of the hour. As such, this paper aims to develop a robust and intelligent optimal power flow controller using a grasshopper optimization algorithm (GOA) to optimize the dynamic response and power quality of the grid-connected MG while sharing the desired amount of power with the grid. To validate the effectiveness of proposed GOA-based controller, its performance in achieving the desired power sharing ratio with optimal dynamic response and power quality is compared with that of its precedent particle swarm optimization (PSO)-based controller under MG injection and abrupt load change conditions. The proposed controller provides tremendous system’s dynamic response with minimum current harmonic distortion even at higher DG penetration levels. Full article
(This article belongs to the Special Issue Power Quality in Smart Grids)
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Open AccessEditorial
Acknowledgement to Reviewers of Electronics in 2018
Electronics 2019, 8(1), 110; https://doi.org/10.3390/electronics8010110
Published: 19 January 2019
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Abstract
Rigorous peer-review is the cornerstone of high-quality academic publishing [...] Full article
Open AccessArticle
Systematic Implementation of Multi-Phase Power Supply (Three to Six) Conversion System
Electronics 2019, 8(1), 109; https://doi.org/10.3390/electronics8010109
Received: 10 December 2018 / Revised: 7 January 2019 / Accepted: 14 January 2019 / Published: 18 January 2019
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Abstract
Multiphase (more than three) power system has gained popularity due to their inherent advantages when compared to three-phase counterpart. Multiphase power supply is extensively used in AC/DC multi-pulse converters, especially supply with multiple of three-phases. AC/DC converter with multi-pulse input is a popular [...] Read more.
Multiphase (more than three) power system has gained popularity due to their inherent advantages when compared to three-phase counterpart. Multiphase power supply is extensively used in AC/DC multi-pulse converters, especially supply with multiple of three-phases. AC/DC converter with multi-pulse input is a popular solution to reduce the ripple in the DC output. Single-phase and three-phase transformers and phase transformation from single to multiphase are employed in variable speed drives application to feed the multi-cell H-Bridge converters and multi-pulse AC-DC converters. Six-phase system is extensively discussed in the literature for numerous applications ranging from variable speed drives to multiphase wind energy generation system. This paper shows the systematic phase transformation technique from three-phase to six-phase (both symmetrical and asymmetrical) for both understanding and teaching purposes. Such an approach could help students understand a promising advanced concept in their undergraduate courses. When phase difference between the two consecutive phases of six phases has a phase difference of 60°, it is called a symmetrical six-phase system; while an asymmetrical or quasi, six-phase has two set of three-phase with a phase shift of 30° between the two sets. Simulation and experimental results are also presented. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
A Variation-Aware Design Methodology for Distributed Arithmetic
Electronics 2019, 8(1), 108; https://doi.org/10.3390/electronics8010108
Received: 13 December 2018 / Revised: 9 January 2019 / Accepted: 16 January 2019 / Published: 18 January 2019
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Abstract
Distributed arithmetic (DA) brings area and power benefits to digital designs relevant to the Internet-of-Things. Therefore, new error resilient techniques for DA computation are urgently required to improve robustness against the process, voltage, and temperature (PVT) variations. This paper proposes a new in-situ [...] Read more.
Distributed arithmetic (DA) brings area and power benefits to digital designs relevant to the Internet-of-Things. Therefore, new error resilient techniques for DA computation are urgently required to improve robustness against the process, voltage, and temperature (PVT) variations. This paper proposes a new in-situ timing error prevention technique to mitigate the impact of variations in DA circuits by providing a guardband for significant (most significant bit) computations. This guardband is initially achieved by modifying the sign extension block and carefully gate-sizing. Therefore, least significant bit (LSB) computation can correspond to the critical path, and timing error can be tolerated at the cost of acceptable accuracy loss. Our approach is demonstrated on a 16-tap finite impulse respons (FIR) filter using the 65 nm CMOS process and the simulation results show that this design can still maintain high-accuracy performance without worst case timing margin, and achieve up to 32 % power savings by voltage scaling when the worst case margin is considered with only 9 % area overhead. Full article
(This article belongs to the Special Issue VLSI Architecture Design for Digital Signal Processing)
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Open AccessArticle
Longitudinal Attitude Control Decoupling Algorithm Based on the Fuzzy Sliding Mode of a Coaxial-Rotor UAV
Electronics 2019, 8(1), 107; https://doi.org/10.3390/electronics8010107
Received: 21 December 2018 / Revised: 14 January 2019 / Accepted: 14 January 2019 / Published: 18 January 2019
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Abstract
A longitudinal attitude decoupling algorithm based on the fuzzy sliding mode control for a small coaxial rotor unmanned aerial vehicle (UAV) is presented in this paper. The attitude system of a small coaxial rotor UAV is characterized by nonlinearity, strong coupling and uncertainty, [...] Read more.
A longitudinal attitude decoupling algorithm based on the fuzzy sliding mode control for a small coaxial rotor unmanned aerial vehicle (UAV) is presented in this paper. The attitude system of a small coaxial rotor UAV is characterized by nonlinearity, strong coupling and uncertainty, which causes difficulties pertaining to its flight control. According to its six-degree-of-freedom model and structural characteristics, the dynamic model was established, and a longitudinal attitude decoupling algorithm was proposed. A fuzzy sliding mode control was used to design the controller to adapt to the underactuated system. Compared with the uncoupled fuzzy sliding mode control, simulation results indicated that the proposed method could improve the stability of the system, presented with a better adapting ability, and could effectively suppress the modeling error and external interference of the coaxial rotor aircraft attitude system. The proposed method also has the advantages of high accuracy, good stability, and the ease of implementation. Full article
(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)
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Open AccessArticle
Drift-Diffusion Simulation of High-Speed Optoelectronic Devices
Electronics 2019, 8(1), 106; https://doi.org/10.3390/electronics8010106
Received: 30 December 2018 / Revised: 14 January 2019 / Accepted: 15 January 2019 / Published: 18 January 2019
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Abstract
In this paper, we address the problem of research and development of the advanced optoelectronic devices designed for on-chip optical interconnections in integrated circuits. The development of the models, techniques, and applied software for the numerical simulation of carrier transport and accumulation in [...] Read more.
In this paper, we address the problem of research and development of the advanced optoelectronic devices designed for on-chip optical interconnections in integrated circuits. The development of the models, techniques, and applied software for the numerical simulation of carrier transport and accumulation in high-speed AIIIBV (A and B refer to group III and V semiconductors, respectively) optoelectronic devices is the purpose of the paper. We propose the model based on the standard drift-diffusion equations, rate equation for photons in an injection laser, and complex analytical models of carrier mobility, generation, and recombination. To solve the basic equations of the model, we developed the explicit and implicit techniques of drift-diffusion numerical simulation and applied software. These aids are suitable for the stationary and time-domain simulation of injection lasers and photodetectors with various electrophysical, constructive, and technological parameters at different control actions. We applied the model for the simulation of the lasers with functionally integrated amplitude and frequency modulators and uni-travelling-carrier photodetectors. According to the results of non-stationary simulation, it is reasonable to optimize the parameters of the lasers-modulators and develop new construction methods aimed at the improvement of photodetectors’ response time. Full article
(This article belongs to the Section Microelectronics and Optoelectronics)
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Open AccessArticle
Energy-Efficient Gabor Kernels in Neural Networks with Genetic Algorithm Training Method
Electronics 2019, 8(1), 105; https://doi.org/10.3390/electronics8010105
Received: 21 December 2018 / Revised: 10 January 2019 / Accepted: 16 January 2019 / Published: 18 January 2019
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Abstract
Deep-learning convolutional neural networks (CNNs) have proven to be successful in various cognitive applications with a multilayer structure. The high computational energy and time requirements hinder the practical application of CNNs; hence, the realization of a highly energy-efficient and fast-learning neural network has [...] Read more.
Deep-learning convolutional neural networks (CNNs) have proven to be successful in various cognitive applications with a multilayer structure. The high computational energy and time requirements hinder the practical application of CNNs; hence, the realization of a highly energy-efficient and fast-learning neural network has aroused interest. In this work, we address the computing-resource-saving problem by developing a deep model, termed the Gabor convolutional neural network (Gabor CNN), which incorporates highly expression-efficient Gabor kernels into CNNs. In order to effectively imitate the structural characteristics of traditional weight kernels, we improve upon the traditional Gabor filters, having stronger frequency and orientation representations. In addition, we propose a procedure to train Gabor CNNs, termed the fast training method (FTM). In FTM, we design a new training method based on the multipopulation genetic algorithm (MPGA) and evaluation structure to optimize improved Gabor kernels, but train the rest of the Gabor CNN parameters with back-propagation. The training of improved Gabor kernels with MPGA is much more energy-efficient with less samples and iterations. Simple tasks, like character recognition on the Mixed National Institute of Standards and Technology database (MNIST), traffic sign recognition on the German Traffic Sign Recognition Benchmark (GTSRB), and face detection on the Olivetti Research Laboratory database (ORL), are implemented using LeNet architecture. The experimental result of the Gabor CNN and MPGA training method shows a 17–19% reduction in computational energy and time and an 18–21% reduction in storage requirements with a less than 1% accuracy decrease. We eliminated a significant fraction of the computation-hungry components in the training process by incorporating highly expression-efficient Gabor kernels into CNNs. Full article
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Open AccessArticle
Research on an Auto-Optimized Capacitor Voltage Balancing Control Strategy of MMC SM for Renewable Energy HVDC Transmission System
Electronics 2019, 8(1), 104; https://doi.org/10.3390/electronics8010104
Received: 11 December 2018 / Revised: 6 January 2019 / Accepted: 14 January 2019 / Published: 18 January 2019
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Abstract
The Modular Multilevel Converter (MMC) is one of the most attractive converter topologies in the High Voltage Direct Current (HVDC) transmission field. The latest widely used sorting method has a low algorithm complexity. It can effectively balance the sub-module (SM) capacitor voltages, but [...] Read more.
The Modular Multilevel Converter (MMC) is one of the most attractive converter topologies in the High Voltage Direct Current (HVDC) transmission field. The latest widely used sorting method has a low algorithm complexity. It can effectively balance the sub-module (SM) capacitor voltages, but it would cause relatively high switching frequency and power loss. Aiming at the problem that the sub-module (SM) capacitor voltage sorting algorithm has a large switching loss due to the high switching frequency of the device, this paper proposes an auto-optimized capacitor voltage balancing control strategy. Firstly, the topology and operation principle of MMC are analyzed. Secondly, a SM capacitor voltage control method based on the dynamic deviation threshold is proposed. Considering the switch switching state of the SM and the difference between the voltages of each SM, the algorithm can obtain the dynamic deviation valve using the closed-loop control. The method can avoid the unnecessary repeated switching of the Insulated Gate Bipolar Transistor (IGBT) under the premise of ensuring that the capacitance voltages of the SMs are basically the same, which effectively result in reducing the switching frequency of the MMC SM and reducing the switching loss, thereby improving the operating efficiency of the system. Finally aiming at the proposed control strategy, the simulation and experimental verification are carried out which shows that the proposed algorithm can better control the system voltage deviation, reduce the switching loss of the system and improve the stability of the system. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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Open AccessFeature PaperArticle
A Simple Indoor Localization Methodology for Fast Building Classification Models Based on Fingerprints
Electronics 2019, 8(1), 103; https://doi.org/10.3390/electronics8010103
Received: 20 November 2018 / Revised: 11 January 2019 / Accepted: 15 January 2019 / Published: 17 January 2019
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Abstract
Indoor localization has received tremendous attention in the last two decades due to location-aware services being highly demanded. Wireless networks have been suggested to solve this problem in many research works, and efficient algorithms have been developed with precise location and high accuracy. [...] Read more.
Indoor localization has received tremendous attention in the last two decades due to location-aware services being highly demanded. Wireless networks have been suggested to solve this problem in many research works, and efficient algorithms have been developed with precise location and high accuracy. Nevertheless, those approaches often have high computational and high energy consumption. Hence, in temporary environments, such as emergency situations, where a fast deployment of an indoor localization system is required, those methods are not appropriate. In this manuscript, a methodology for fast building of an indoor localization system is proposed. For that purpose, a reduction of the data dimensionality is achieved by applying data fusion and feature transformation, which allow us to reduce the computational cost of the classifier training phase. In order to validate the methodology, three different datasets were used: two of them are public datasets based mainly on Received Signal Strength (RSS) from different Wi-Fi access point, and the third is a set of RSS values gathered from the LED lamps in a Visible Light Communication (VLC) network. The simulation results show that the proposed methodology considerably amends the overall computational performance and provides an acceptable location estimation error. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessArticle
Rapid Prototyping of a Hybrid PV–Wind Generation System Implemented in a Real-Time Digital Simulation Platform and Arduino
Electronics 2019, 8(1), 102; https://doi.org/10.3390/electronics8010102
Received: 15 December 2018 / Revised: 12 January 2019 / Accepted: 12 January 2019 / Published: 17 January 2019
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Abstract
The growing penetration of generation systems based on renewable energy in electric power systems is undeniable. These generation systems have many benefits, but also many challenges from the technical point of view. One of the biggest problems in the case of solar photovoltaic [...] Read more.
The growing penetration of generation systems based on renewable energy in electric power systems is undeniable. These generation systems have many benefits, but also many challenges from the technical point of view. One of the biggest problems in the case of solar photovoltaic (PV) and wind energy is the intermittency of the raw material, thus hybrid generation systems that contain both sources are being used to complement electric power generation. To analyze the problems of this type of hybrid generation systems, it is necessary to develop models and test systems that allows to study their dynamic behavior. Reported in this paper is the implementation of a full hybrid PV–wind generation system model in a real-time digital simulation platform, and the development of the electronic converter controls. These controllers were implemented in digital devices (Arduino Due) and connected to the simulation platform to test their performance in real-time. In addition, the procedure followed for the development and implementation of the controllers is presented. The proposed test system can be used in renewable energy integration studies and the development of new control strategies. Full article
(This article belongs to the Special Issue Grid Connected Photovoltaic Systems)
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Open AccessArticle
An X-Band 40 W Power Amplifier GaN MMIC Design by Using Equivalent Output Impedance Model
Electronics 2019, 8(1), 99; https://doi.org/10.3390/electronics8010099
Received: 7 November 2018 / Revised: 9 January 2019 / Accepted: 10 January 2019 / Published: 16 January 2019
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Abstract
This paper presents an X-band 40 W power amplifier with high efficiency based on 0.25 μm GaN HEMT (High Electron Mobility Transistor) on SiC process. An equivalent RC (Resistance Capacitance) model is presented to provide accurate large-signal output impedances of GaN HEMTs with [...] Read more.
This paper presents an X-band 40 W power amplifier with high efficiency based on 0.25 μm GaN HEMT (High Electron Mobility Transistor) on SiC process. An equivalent RC (Resistance Capacitance) model is presented to provide accurate large-signal output impedances of GaN HEMTs with arbitrary dimensions. By introducing the band-pass filter topology, broadband impedance matching networks are achieved based on the RC model, and the power amplifier MMIC (Monolithic Microwave Integrated Circuit) with enhanced bandwidth is realized. The measurement results show that this power amplifier at 28 V operation voltage achieved over 40 W output power, 44.7% power-added efficiency and 22 dB power gain from 8 GHz to 12 GHz. The total chip size is 3.20 mm × 3.45 mm. Full article
(This article belongs to the Section Microelectronics and Optoelectronics)
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Open AccessArticle
Fully Integrated Low-Ripple Switched-Capacitor DC–DC Converter with Parallel Low-Dropout Regulator
Electronics 2019, 8(1), 98; https://doi.org/10.3390/electronics8010098
Received: 20 November 2018 / Revised: 5 January 2019 / Accepted: 11 January 2019 / Published: 16 January 2019
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Abstract
In this paper, we propose a fully integrated switched-capacitor DC–DC converter with low ripple and fast transient response for portable low-power electronic devices. The proposed converter reduces the output ripple by filtering the control ripple via combining a low-dropout regulator with a main [...] Read more.
In this paper, we propose a fully integrated switched-capacitor DC–DC converter with low ripple and fast transient response for portable low-power electronic devices. The proposed converter reduces the output ripple by filtering the control ripple via combining a low-dropout regulator with a main switched-capacitor DC–DC converter with a four-bit digital capacitance modulation control. In addition, the four-phase interleaved technique applied to the main converter reduces the switching ripple. The proposed converter provides an output voltage ranging from 1.2 to 1.5 V from a 3.3 V supply. Its peak efficiency reaches 73% with ripple voltages below 55 mV over the entire output power range. The transient response time for a load current variation from 100 μA to 50 mA is measured to be 800 ns. Importantly, the converter chip, which is fabricated using 0.13 μm complementary metal–oxide–semiconductor (CMOS) technology, has a size of 2.04 mm2. We believe that our approach can contribute to advancements in power sources for applications such as wearable electronics and the Internet of Things. Full article
(This article belongs to the Special Issue Signal Processing and Analysis of Electrical Circuit)
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Open AccessFeature PaperArticle
Improving RF Fingerprinting Methods by Means of D2D Communication Protocol
Electronics 2019, 8(1), 97; https://doi.org/10.3390/electronics8010097
Received: 4 December 2018 / Revised: 10 January 2019 / Accepted: 11 January 2019 / Published: 16 January 2019
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Abstract
Radio Frequency (RF) fingerprinting is widely applied for indoor positioning due to the existing Wi-Fi infrastructure present in most indoor spaces (home, work, leisure, among others) and the widespread usage of smartphones everywhere. It corresponds to a simple idea, the signal signature in [...] Read more.
Radio Frequency (RF) fingerprinting is widely applied for indoor positioning due to the existing Wi-Fi infrastructure present in most indoor spaces (home, work, leisure, among others) and the widespread usage of smartphones everywhere. It corresponds to a simple idea, the signal signature in a location tends to be stable over the time. Therefore, with the signals received from multiple APs, a unique fingerprint can be created. However, the Wi-Fi signal is affected by many factors which degrade the positioning error range to around a few meters. This paper introduces a collaborative method based on device-to-device (D2D) communication to improve the positioning accuracy using only fingerprinting and the direct communication to nearby devices. The results presented in this paper show that the positioning error can be reduced around 44% by considering D2D communication in the operational stage without adding new infrastructure for fingerprinting or complex resource-consuming filters. Moreover, the presence of very large errors is significantly reduced when the collaborative positioning based on D2D is available. Full article
(This article belongs to the Special Issue Green Communications in Smart City)
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Open AccessArticle
Joint Power Allocation for Coordinated Multi-Point Diversity Transmission in Rayleigh Fading Channels
Electronics 2019, 8(1), 101; https://doi.org/10.3390/electronics8010101
Received: 7 December 2018 / Revised: 9 January 2019 / Accepted: 14 January 2019 / Published: 16 January 2019
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Abstract
We consider the problem of joint power allocation (JPA) in a coordinated multi-point (CoMP) joint diversity transmission (JDT) network with a total coordination point power (TCPP) constraint, aimed at maximizing the ergodic cooperative capacity (ECC) in Rayleigh fading channels. In this paper, we [...] Read more.
We consider the problem of joint power allocation (JPA) in a coordinated multi-point (CoMP) joint diversity transmission (JDT) network with a total coordination point power (TCPP) constraint, aimed at maximizing the ergodic cooperative capacity (ECC) in Rayleigh fading channels. In this paper, we first extend the JPA problem in the coordinated two-point (Co2P) JDT networkto the case of a non-unity TCPP constraint. Furthermore, we introduce more accurate log-quadratic approximated (LQA) expressions to obtain the coordinated transmission point (CTP) powers. Next, we extend our study to a coordinated three-point (Co3P) JDT network. Given the mean branch gain-to-noise ratios, we first obtain a log-linear approximated (LLA) expression for obtaining the optimum power of the third CTP (i.e., the worst quality-providing CTP). After obtaining the third-CTP power, we obtain the CTP powers of two better quality-providing CTPs by invoking the LLA CTP power expressions for Co2P JDT power allocation, under the remaining power given by the TCPP minus the third-CTP power. The numerical results demonstrate that the LQA and LLA CTP power expressions for Co2P JDT and the LLA CTP power expressions for Co3P JDT are very efficient in terms of the simplicity for JPA and CoMP set selection, as well as the resulting ECC. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Breast Cancer Detection in Thermal Infrared Images Using Representation Learning and Texture Analysis Methods
Electronics 2019, 8(1), 100; https://doi.org/10.3390/electronics8010100
Received: 3 December 2018 / Revised: 10 January 2019 / Accepted: 11 January 2019 / Published: 16 January 2019
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Abstract
Nowadays, breast cancer is one of the most common cancers diagnosed in women. Mammography is the standard screening imaging technique for the early detection of breast cancer. However, thermal infrared images (thermographies) can be used to reveal lesions in dense breasts. In these [...] Read more.
Nowadays, breast cancer is one of the most common cancers diagnosed in women. Mammography is the standard screening imaging technique for the early detection of breast cancer. However, thermal infrared images (thermographies) can be used to reveal lesions in dense breasts. In these images, the temperature of the regions that contain tumors is warmer than the normal tissue. To detect that difference in temperature between normal and cancerous regions, a dynamic thermography procedure uses thermal infrared cameras to generate infrared images at fixed time steps, obtaining a sequence of infrared images. In this paper, we propose a novel method to model the changes on temperatures in normal and abnormal breasts using a representation learning technique called learning-to-rank and texture analysis methods. The proposed method generates a compact representation for the infrared images of each sequence, which is then exploited to differentiate between normal and cancerous cases. Our method produced competitive (AUC = 0.989) results when compared to other studies in the literature. Full article
(This article belongs to the Section Bioelectronics)
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Open AccessArticle
Certificate Based Security Mechanisms in Vehicular Ad-Hoc Networks based on IEC 61850 and IEEE WAVE Standards
Electronics 2019, 8(1), 96; https://doi.org/10.3390/electronics8010096
Received: 13 November 2018 / Revised: 7 January 2019 / Accepted: 10 January 2019 / Published: 15 January 2019
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Abstract
When equipped with an on-board wireless kit, electric vehicles (EVs) can communicate with nearby entities, e.g., road side units (RSUs), via a vehicle ad-hoc network (VANET). More observability enables smart charging algorithms where charging stations (CSs) are allocated to EVs based on their [...] Read more.
When equipped with an on-board wireless kit, electric vehicles (EVs) can communicate with nearby entities, e.g., road side units (RSUs), via a vehicle ad-hoc network (VANET). More observability enables smart charging algorithms where charging stations (CSs) are allocated to EVs based on their current state of charge, destination, and urgency to charge. IEEE 1609 WAVE standard regulates VANETs, while IEC 61850 is emerging as the smart grid communication standard. In order to integrate these two domains of energy management, past research has focused on harmonizing these two standards for a full smart city solution. However, this solution requires very sensitive data to be transmitted, such as ownership of EV, owners’ personal details, and driving history. Therefore, data security in these networks is of prime concern and needs to be addressed. In this paper, different security mechanisms defined by the IEEE 1609 WAVE standard are applied for both vehicle-to-infrastructure (V2I) and vehicle-to-grid (V2G) communication. The former relates to EV–RSU, while the latter covers EV–CS communication. The implicit and explicit certificate mechanism processes proposed in IEEE 1609 WAVE for authentication are studied in great detail. Furthermore, a performance evaluation for these mechanisms is presented in terms of total time lapse for authentication, considering both the computational time and communication time delays. These results are very important in understanding the extra latency introduced by security mechanisms. Considering that VANETs may be volatile and may disappear as EVs drive away, overall timing performance becomes vital for operation. Reported results show the magnitude of this impact and compare different security mechanisms. These can be utilized to further develop VANET security approaches based on available time and the required security level. Full article
(This article belongs to the Special Issue Smart, Connected and Efficient Transportation Systems)
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Open AccessArticle
Design of Voltage Mode Electronically Tunable First Order All Pass Filter in ±0.7 V 16 nm CNFET Technology
Electronics 2019, 8(1), 95; https://doi.org/10.3390/electronics8010095
Received: 11 November 2018 / Revised: 7 January 2019 / Accepted: 9 January 2019 / Published: 15 January 2019
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Abstract
A novel voltage mode first order active only tuneable all pass filter (AOTAPF) circuit configuration is presented. The AOTAPF has been designed using ±0.7 V, 16 nm carbon nanotube field effect transistor (CNFET) Technology. The circuit uses CNFET based varactor and unity gain [...] Read more.
A novel voltage mode first order active only tuneable all pass filter (AOTAPF) circuit configuration is presented. The AOTAPF has been designed using ±0.7 V, 16 nm carbon nanotube field effect transistor (CNFET) Technology. The circuit uses CNFET based varactor and unity gain inverting amplifier (UGIA). The presented AOTAPF is realized with three N-type CNFETs and without any external passive components. It is to be noted that the realized circuit uses only two CNFETs between its supply-rails and thus, suitable for low-voltage operation. The electronic tunability is achieved by varying the voltage controlled capacitance of the employed CNFET varactor. By altering the varactor tuning voltage, a wide tunable range of pole frequency between 34.2 GHz to 56.9 GHz is achieved. The proposed circuit does not need any matching constraint and is suitable for multi-GHz frequency applications. The presented AOTAPF performance is substantiated with HSPICE simulation program for 16 nm technology-node, using the well-known Stanford CNFET model. AOTAPF simulation results verify the theory for a wide frequency-range. Full article
(This article belongs to the Special Issue Signal Processing and Analysis of Electrical Circuit)
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Open AccessArticle
AnScalable Matrix Computing Unit Architecture for FPGA, and SCUMO User Design Interface
Electronics 2019, 8(1), 94; https://doi.org/10.3390/electronics8010094
Received: 30 November 2018 / Revised: 21 December 2018 / Accepted: 11 January 2019 / Published: 15 January 2019
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Abstract
High dimensional matrix algebra is essential in numerous signal processing and machine learning algorithms. This work describes a scalable square matrix-computing unit designed on the basis of circulant matrices. It optimizes data flow for the computation of any sequence of matrix operations removing [...] Read more.
High dimensional matrix algebra is essential in numerous signal processing and machine learning algorithms. This work describes a scalable square matrix-computing unit designed on the basis of circulant matrices. It optimizes data flow for the computation of any sequence of matrix operations removing the need for data movement for intermediate results, together with the individual matrix operations’ performance in direct or transposed form (the transpose matrix operation only requires a data addressing modification). The allowed matrix operations are: matrix-by-matrix addition, subtraction, dot product and multiplication, matrix-by-vector multiplication, and matrix by scalar multiplication. The proposed architecture is fully scalable with the maximum matrix dimension limited by the available resources. In addition, a design environment is also developed, permitting assistance, through a friendly interface, from the customization of the hardware computing unit to the generation of the final synthesizable IP core. For N × N matrices, the architecture requires N ALU-RAM blocks and performs O ( N 2 ) , requiring N 2 + 7 and N + 7 clock cycles for matrix-matrix and matrix-vector operations, respectively. For the tested Virtex7 FPGA device, the computation for 500 × 500 matrices allows a maximum clock frequency of 346 MHz, achieving an overall performance of 173 GOPS. This architecture shows higher performance than other state-of-the-art matrix computing units. Full article
(This article belongs to the Special Issue Hardware and Architecture)
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Open AccessArticle
A Novel Differential Fault Analysis on the Key Schedule of SIMON Family
Electronics 2019, 8(1), 93; https://doi.org/10.3390/electronics8010093
Received: 11 December 2018 / Revised: 3 January 2019 / Accepted: 10 January 2019 / Published: 15 January 2019
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Abstract
As a family of lightweight block ciphers, SIMON has attracted lots of research attention since its publication in 2013. Recent works show that SIMON is vulnerable to differential fault analysis (DFA) and existing DFAs on SIMON assume the location of induced faults are [...] Read more.
As a family of lightweight block ciphers, SIMON has attracted lots of research attention since its publication in 2013. Recent works show that SIMON is vulnerable to differential fault analysis (DFA) and existing DFAs on SIMON assume the location of induced faults are on the cipher states. In this paper, a novel DFA on SIMON is proposed where the key schedule is selected as the location of induced faults. Firstly, we assume a random one-bit fault is induced in the fourth round key KT−4 to the last. Then, by utilizing the key schedule propagation properties of SIMON, we determine the exact position of induced fault and demonstrate that the proposed DFA can retrieve 4 bits of the last round key KT−1 on average using one-bit fault. Till now this is the largest number of bits that can be cracked as compared to DFAs based on random bit fault model. Furthermore, by reusing the induced fault, we prove that 2 bits of the penultimate round key KT−2 could be retrieved. To the best of our knowledge, the proposed attack is the first one which extracts a key from SIMON based upon DFA on the key schedule. Finally, correctness and validity of our proposed attack is verified through detailed simulation and analysis. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Open AccessArticle
Novel Dead-Time Compensation Strategy for Wide Current Range in a Three-Phase Inverter
Electronics 2019, 8(1), 92; https://doi.org/10.3390/electronics8010092
Received: 16 November 2018 / Revised: 13 December 2018 / Accepted: 23 December 2018 / Published: 15 January 2019
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Abstract
This paper proposes a novel three-phase voltage source inverter dead-time compensation strategy for accurate compensation in wide current regions of the inverter. In particular, an analysis of the output voltage distortion of the inverter, which appears as parasitic components of the switches, was [...] Read more.
This paper proposes a novel three-phase voltage source inverter dead-time compensation strategy for accurate compensation in wide current regions of the inverter. In particular, an analysis of the output voltage distortion of the inverter, which appears as parasitic components of the switches, was conducted for proper voltage compensation in the low current region, and an on-line compensation voltage controller was proposed. Additionally, a new trapezoidal compensation voltage implementation method using the current phase was proposed to simplify realizing the trapezoidal shape of the three-phase compensation voltages. Finally, when the proposed dead-time compensation strategy was applied, the maximum phase voltage magnitude in the linear modulation voltage regions was defined to achieve smooth operation even at high modulation index. Simulations and experiments were conducted to verify the performance of the proposed dead-time compensation scheme. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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Open AccessFeature PaperArticle
Assessment of Dual Frequency GNSS Observations from a Xiaomi Mi 8 Android Smartphone and Positioning Performance Analysis
Electronics 2019, 8(1), 91; https://doi.org/10.3390/electronics8010091
Received: 31 October 2018 / Revised: 8 January 2019 / Accepted: 9 January 2019 / Published: 15 January 2019
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Abstract
On May 2018 the world’s first dual-frequency Global Navigation Satellite System (GNSS) smartphone produced by Xiaomi equipped with a Broadcom BCM47755 chip was launched. It is able to receive L1/E1/ and L5/E5 signals from GPS, Galileo, Beidou, and GLONASS (GLObal NAvigation Satellite System) [...] Read more.
On May 2018 the world’s first dual-frequency Global Navigation Satellite System (GNSS) smartphone produced by Xiaomi equipped with a Broadcom BCM47755 chip was launched. It is able to receive L1/E1/ and L5/E5 signals from GPS, Galileo, Beidou, and GLONASS (GLObal NAvigation Satellite System) satellites. The main aim of this work is to achieve the phone’s position by using multi-constellation, dual frequency pseudorange and carrier phase raw data collected from the smartphone. Furthermore, the availability of dual frequency raw data allows to assess the multipath performance of the device. The smartphone’s performance is compared with that of a geodetic receiver. The experiments were conducted in two different scenarios to test the smartphone under different multipath conditions. Smartphone measurements showed a lower C/N0 and higher multipath compared with those of the geodetic receiver. This produced negative effects on single-point positioning as showed by high root mean square error (RMS). The best positioning accuracy for single point was obtained with the E5 measurements with a DRMS (horizontal root mean square error) of 4.57 m. For E1/L1 frequency, the 2DRMS was 5.36 m. However, the Xiaomi Mi 8, thanks to the absence of the duty cycle, provided carrier phase measurements used for a static single frequency relative positioning with an achieved 2DRMS of 1.02 and 1.95 m in low and high multipath sites, respectively. Full article
(This article belongs to the Special Issue Green Communications in Smart City)
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Open AccessArticle
Shannon Entropy Index and a Fuzzy Logic System for the Assessment of Stator Winding Short-Circuit Faults in Induction Motors
Electronics 2019, 8(1), 90; https://doi.org/10.3390/electronics8010090
Received: 28 November 2018 / Revised: 5 January 2019 / Accepted: 9 January 2019 / Published: 15 January 2019
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Abstract
The induction motor (IM) is one of the most important elements in industry. Although IMs are robust machines, they are susceptible to faults, where the stator winding short-circuit fault is one of the most common ones. In this work, the Shannon entropy (SE) [...] Read more.
The induction motor (IM) is one of the most important elements in industry. Although IMs are robust machines, they are susceptible to faults, where the stator winding short-circuit fault is one of the most common ones. In this work, the Shannon entropy (SE) index and a fuzzy logic (FL) system are proposed to diagnose short-circuit faults, considering both different severity levels and different load conditions. In the proposed methodology, a filtering stage based on brick-wall band-pass filters is firstly carried out. After this stage, the SE index is computed to quantify the fault severity and a FL system is applied to diagnose the IM condition in an automatic way. Unlike other works that propose some types of space transformations, the proposal is only based on a filtering stage and a time domain index, requiring low computational resources. The obtained results demonstrate the effectiveness of the proposal, i.e., the SE index quantifies the fault severity, regardless of the mechanical load, and the proposed FL system achieves a positive classification rate of 98%. Full article
(This article belongs to the Special Issue Signal Processing and Analysis of Electrical Circuit)
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Open AccessArticle
Predicting the Influence of Rain on LIDAR in ADAS
Electronics 2019, 8(1), 89; https://doi.org/10.3390/electronics8010089
Received: 19 December 2018 / Revised: 9 January 2019 / Accepted: 10 January 2019 / Published: 15 January 2019
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Abstract
While it is well known that rain may influence the performance of automotive LIDAR sensors commonly used in ADAS applications, there is a lack of quantitative analysis of this effect. In particular, there is very little published work on physically-based simulation of the [...] Read more.
While it is well known that rain may influence the performance of automotive LIDAR sensors commonly used in ADAS applications, there is a lack of quantitative analysis of this effect. In particular, there is very little published work on physically-based simulation of the influence of rain on terrestrial LIDAR performance. Additionally, there have been few quantitative studies on how rain-rate influences ADAS performance. In this work, we develop a mathematical model for the performance degradation of LIDAR as a function of rain-rate and incorporate this model into a simulation of an obstacle-detection system to show how it can be used to quantitatively predict the influence of rain on ADAS that use LIDAR. Full article
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Open AccessFeature PaperArticle
Medical Video Coding Based on 2nd-Generation Wavelets: Performance Evaluation
Electronics 2019, 8(1), 88; https://doi.org/10.3390/electronics8010088
Received: 5 October 2018 / Revised: 26 December 2018 / Accepted: 8 January 2019 / Published: 14 January 2019
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Abstract
The operations of digitization, transmission and storage of medical data, particularly images, require increasingly effective encoding methods not only in terms of compression ratio and flow of information but also in terms of visual quality. At first, there was DCT (discrete cosine transform) [...] Read more.
The operations of digitization, transmission and storage of medical data, particularly images, require increasingly effective encoding methods not only in terms of compression ratio and flow of information but also in terms of visual quality. At first, there was DCT (discrete cosine transform) then DWT (discrete wavelet transform) and their associated standards in terms of coding and image compression. The 2nd-generation wavelets seeks to be positioned and confronted by the image and video coding methods currently used. It is in this context that we suggest a method combining bandelets and the SPIHT (set partitioning in hierarchical trees) algorithm. There are two main reasons for our approach: the first lies in the nature of the bandelet transform to take advantage of capturing the geometrical complexity of the image structure. The second reason is the suitability of encoding the bandelet coefficients by the SPIHT encoder. Quality measurements indicate that in some cases (for low bit rates) the performance of the proposed coding competes with the well-established ones (H.264 or MPEG4 AVC and H.265 or MPEG4 HEVC) and opens up new application prospects in the field of medical imaging. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessFeature PaperArticle
Step-Down Partial Power DC-DC Converters for Two-Stage Photovoltaic String Inverters
Electronics 2019, 8(1), 87; https://doi.org/10.3390/electronics8010087
Received: 11 December 2018 / Revised: 8 January 2019 / Accepted: 9 January 2019 / Published: 12 January 2019
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Abstract
Photovoltaic (PV) systems composed by two energy conversion stages are attractive from an operation point of view. This is because the maximum power point tracking (MPPT) range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the [...] Read more.
Photovoltaic (PV) systems composed by two energy conversion stages are attractive from an operation point of view. This is because the maximum power point tracking (MPPT) range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the additional dc-dc conversion stage increases the volume, cost and power converter losses. Therefore, central inverters based on a single-stage converter, have been a mainstream solution to interface large-scale PV arrays composed of several strings connected in parallel made by the series connections of PV modules. The concept of partial power converters (PPC), previously reported as a voltage step-up stage, has not addressed in depth for all types of PV applications. In this work, a PPC performing voltage step-down operation is proposed and analyzed. This concept is interesting from the industry point of view, since with the new isolation standards of PV modules are reaching 1500 V, increasing both the size of the string and dc-link voltage for single-stage inverters. Since grid connection remains typically at 690 V, larger strings impose more demanding operation for single-stage central inverters (required to operate at lower modulation indexes and demand higher blocking voltage devices), making the proposed step-down PPC an attractive solution. Theoretical analysis and an experimental test-bench was built in order to validate the PPC concept, the control performance and the improvement of the conversion efficiency. The experimental results corroborate the benefits of using a PPC, in terms of increasing the system efficiency by reducing the processed power of the converter, while not affecting the system performance. Full article
(This article belongs to the Special Issue Advanced Power Conversion Technologies)
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Open AccessArticle
Hyperspectral Image Denoising Based on Spectral Dictionary Learning and Sparse Coding
Electronics 2019, 8(1), 86; https://doi.org/10.3390/electronics8010086
Received: 11 November 2018 / Revised: 21 December 2018 / Accepted: 8 January 2019 / Published: 12 January 2019
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Abstract
Processing and applications of hyperspectral images (HSI) are limited by the noise component. This paper establishes an HSI denoising algorithm by applying dictionary learning and sparse coding theory, which is extended into the spectral domain. First, the HSI noise model under additive noise [...] Read more.
Processing and applications of hyperspectral images (HSI) are limited by the noise component. This paper establishes an HSI denoising algorithm by applying dictionary learning and sparse coding theory, which is extended into the spectral domain. First, the HSI noise model under additive noise assumption was studied. Considering the spectral information of HSI data, a novel dictionary learning method based on an online method is proposed to train the spectral dictionary for denoising. With the spatial–contextual information in the noisy HSI exploited as a priori knowledge, the total variation regularizer is introduced to perform the sparse coding. Finally, sparse reconstruction is implemented to produce the denoised HSI. The performance of the proposed approach is better than the existing algorithms. The experiments illustrate that the denoising result obtained by the proposed algorithm is at least 1 dB better than that of the comparison algorithms. The intrinsic details of both spatial and spectral structures can be preserved after significant denoising. Full article
(This article belongs to the Section Computer Science & Engineering)
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